WO2020191584A1

WO2020191584A1 - Radio network temporary identifier and scrambling for two-step random access channel procedures

Info

Publication number: WO2020191584A1
Application number: PCT/CN2019/079541
Authority: WO
Inventors: Qiaoyu Li; Chao Wei; Ruiming Zheng
Original assignee: Qualcomm Incorporated
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2020-10-01

Abstract

Methods, systems, and devices for wireless communications are described. In some systems, resources for a two-step random access channel (RACH) procedure may be shared with other RACH procedures. As a result, a two-step RACH procedure may utilize various scrambling sequences and message identifiers for transmitting messages between a user equipment (UE) and base station. For example, a scrambling sequence used for a first message of the two-step RACH procedure may be based on information associated with the cell and an identifier associated with resources used for transmitting a preamble sequence. In some cases, a message identifier and a scrambling sequence for a second message of the two-step RACH procedures may be based on the identifier associated with the resources for transmitting the preamble or an identifier conveyed by the first message. Further, respective sets of resources may be configured for different types of RACH procedures that share RACH occasions.

Description

RADIO NETWORK TEMPORARY IDENTIFIER AND SCRAMBLING FOR TWO-STEP RANDOM ACCESS CHANNEL PROCEDURES

BACKGROUND

The following relates generally to wireless communications, and more specifically to radio network temporary identifiers (RNTIs) and scrambling for two-step random access channel (RACH) procedures.

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) . A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE) .

Some wireless systems may support random access procedures for establishing communications between a UE and a base station. The random access procedure may involve a series of handshake messages between the UE and the base station. Additionally, various types of random access procedures may be supported by different devices and the system, where different random access procedures may utilize a different number of handshake messages for establishing communications (such as with two-step random access procedures and four-step random access procedures) . The coexistence of different types of random access procedures within a system may provide challenges.

SUMMARY

The described techniques relate to improved methods, systems, devices, or apparatuses that support radio network temporary identifiers (RNTIs) and scrambling for two-step random access channel (RACH) procedures. In some cases, the described techniques provide for shared RACH occasions for different types of RACH procedures. For instance, a two-step RACH procedure and a four-step RACH procedure may be configured with shared RACH occasions (e.g., time/frequency resources) . As a result, various scrambling sequences and identifiers (e.g., RNTIs) may be used for two-step RACH procedures, where the scrambling sequences may enable a user equipment (UE) and base station to properly identify a payload carried within the different handshake messages of the RACH procedure. Further, the techniques may enable contention resolution for UEs that transmitted preambles (e.g., having the same preamble index) in the same RACH occasion.

In one example, a UE may identify a scrambling sequence based on a message identifier associated with a preamble index, information associated with a cell (e.g., cell-specific parameters such as a cell identifier) and/or an identifier associated with time/frequency resources used for transmitting the preamble in a first message of the two-step RACH procedure (e.g., a random access RNTI (RA-RNTI) ) . The determined scrambling sequence may be used for scrambling a payload of the first message sent to a base station. In some cases, an association between each of a set of message identifiers, a preamble index, a scrambling sequence, cell-specific parameters, or a combination thereof, may be configured by a network and indicated by a base station through broadcast signaling. Additionally, a message identifier and a scrambling sequence for a second message of the two-step RACH procedures may be based on the identifier associated with the time/frequency resources used for transmitting the preamble or a UE identifier in the first message. In such cases, a downlink data payload of the second message may be scrambled using the message identifier for the second message, and a UE may determine that the downlink data payload belongs to the UE based on either the contents of the payload or the UE identifier used to generate the scrambling sequence.

Additionally or alternatively, respective sets of resources may be configured for different types of RACH procedures that share RACH occasions. As an example, different control resource sets (CORESETs) and/or search spaces or different random access response windows may be configured for two-step RACH procedures and four-step RACH procedures. These different resources may be used to distinguish between downlink information sent to a UE for the respective RACH procedures sharing RACH occasions, while both RACH procedures may use the same equation for generating an identifier for downlink messages. In other examples, the same CORESETS and at least partially overlapping random access response windows may be configured for both types of RACH procedures, while an offset included in a message identifier (e.g., for two-step RACH) may provide the differentiation in downlink messages sent to a UE.

A method of wireless communications at a UE is described. The method may include identifying time/frequency resources of a cell for transmitting a first message of a two-step RACH procedure, identifying information associated with the cell, determining a scrambling sequence based on the information associated with the cell and an identifier associated with the time/frequency resources, scrambling a data payload of the first message using the determined scrambling sequence, and transmitting the first message of the two-step RACH procedure, the first message including a preamble sequence and the scrambled data payload.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify time/frequency resources of a cell for transmitting a first message of a two-step RACH procedure, identify information associated with the cell, determine a scrambling sequence based on the information associated with the cell and an identifier associated with the time/frequency resources, scramble a data payload of the first message using the determined scrambling sequence, and transmit the first message of the two-step RACH procedure, the first message including a preamble sequence and the scrambled data payload.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for identifying time/frequency resources of a cell for transmitting a first message of a two-step RACH procedure, identifying information associated with the cell, determining a scrambling sequence based on the information associated with the cell and an identifier associated with the time/frequency resources, scrambling a data payload of the first message using the determined scrambling sequence, and transmitting the first message of the two-step RACH procedure, the first message including a preamble sequence and the scrambled data payload.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to identify time/frequency resources of a cell for transmitting a first message of a two-step RACH procedure, identify information associated with the cell, determine a scrambling sequence based on the information associated with the cell and an identifier associated with the time/frequency resources, scramble a data payload of the first message using the determined scrambling sequence, and transmit the first message of the two-step RACH procedure, the first message including a preamble sequence and the scrambled data payload.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the information associated with the cell may include operations, features, means, or instructions for receiving a broadcast message indicating an association between each of a set of message identifiers and a respective preamble sequence index, and determining the scrambling sequence based on a message identifier of the set of message identifiers associated with the preamble sequence.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the broadcast message includes a system information message broadcast by the cell.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the information associated with the cell may include operations, features, means, or instructions for receiving a cell identifier.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining the scrambling sequence may include operations, features, means, or instructions for determining an association between the scrambling sequence and one or more of the identifier associated with the time/frequency resources for transmitting the first message, the cell identifier, and an index of the preamble sequence.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a broadcast message indicating the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, a configuration of the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence may be predetermined.

A method of wireless communications at a UE is described. The method may include transmitting, to a base station, a first message of a two-step RACH procedure over a set of time/frequency resources, the first message including a preamble sequence and an uplink data payload, receiving, from the base station, a control channel associated with a second message of the two-step RACH procedure, decoding control information from the control channel based on an identifier associated with the set of time/frequency resources of the first message, receiving, based on the control information, a downlink data payload of the second message, determining, based on the identifier associated with the set of time/frequency resources of the first message, a descrambling sequence for the downlink data payload, descrambling the downlink data payload using the descrambling sequence, and identifying that the downlink data payload is associated with the UE based on information included in the downlink data payload.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to transmit, to a base station, a first message of a two-step RACH procedure over a set of time/frequency resources, the first message including a preamble sequence and an uplink data payload, receive, from the base station, a control channel associated with a second message of the two-step RACH procedure, decode control information from the control channel based on an identifier associated with the set of time/frequency resources of the first message, receive, based on the control information, a downlink data payload of the second message, determine, based on the identifier associated with the set of time/frequency resources of the first message, a descrambling sequence for the downlink data payload, descramble the downlink data payload using the descrambling sequence, and identify that the downlink data payload is associated with the UE based on information included in the downlink data payload.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for transmitting, to a base station, a first message of a two-step RACH procedure over a set of time/frequency resources, the first message including a preamble sequence and an uplink data payload, receiving, from the base station, a control channel associated with a second message of the two-step RACH procedure, decoding control information from the control channel based on an identifier associated with the set of time/frequency resources of the first message, receiving, based on the control information, a downlink data payload of the second message, determining, based on the identifier associated with the set of time/frequency resources of the first message, a descrambling sequence for the downlink data payload, descrambling the downlink data payload using the descrambling sequence, and identifying that the downlink data payload is associated with the UE based on information included in the downlink data payload.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to transmit, to a base station, a first message of a two-step RACH procedure over a set of time/frequency resources, the first message including a preamble sequence and an uplink data payload, receive, from the base station, a control channel associated with a second message of the two-step RACH procedure, decode control information from the control channel based on an identifier associated with the set of time/frequency resources of the first message, receive, based on the control information, a downlink data payload of the second message, determine, based on the identifier associated with the set of time/frequency resources of the first message, a descrambling sequence for the downlink data payload, descramble the downlink data payload using the descrambling sequence, and identify that the downlink data payload is associated with the UE based on information included in the downlink data payload.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for identifying that the downlink data payload may be associated with the UE may be based on at least one of a medium access control (MAC) control element, a MAC header, or the control information.

A method of wireless communications at a UE is described. The method may include transmitting, to a base station, a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, receiving, from the base station, a control channel associated with a second message of the two-step RACH procedure, decoding control information from the control channel based on the identifier associated with the first message, receiving, based on the control information, a downlink data payload of the second message, determining, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload, descrambling the downlink data payload using the descrambling sequence, and identifying that the downlink data payload is associated with the UE based on the identifier associated with the first message.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to transmit, to a base station, a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, receive, from the base station, a control channel associated with a second message of the two-step RACH procedure, decode control information from the control channel based on the identifier associated with the first message, receive, based on the control information, a downlink data payload of the second message, determine, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload, descramble the downlink data payload using the descrambling sequence, and identify that the downlink data payload is associated with the UE based on the identifier associated with the first message.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for transmitting, to a base station, a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, receiving, from the base station, a control channel associated with a second message of the two-step RACH procedure, decoding control information from the control channel based on the identifier associated with the first message, receiving, based on the control information, a downlink data payload of the second message, determining, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload, descrambling the downlink data payload using the descrambling sequence, and identifying that the downlink data payload is associated with the UE based on the identifier associated with the first message.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to transmit, to a base station, a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, receive, from the base station, a control channel associated with a second message of the two-step RACH procedure, decode control information from the control channel based on the identifier associated with the first message, receive, based on the control information, a downlink data payload of the second message, determine, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload, descramble the downlink data payload using the descrambling sequence, and identify that the downlink data payload is associated with the UE based on the identifier associated with the first message.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the identifier associated with the first message includes at least a portion of an identifier of the UE.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the identifier associated with the first message includes a scrambling sequence used to scramble the uplink data payload.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the identifier associated with the first message may be based on time/frequency resources for transmitting the first message, an index of the preamble sequence, and a cell identifier.

A method of wireless communications at a UE is described. The method may include transmitting a first message of a RACH procedure over a random access resource, identifying a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitoring for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, decoding control information of the second message based on an identifier associated with the random access resource, and receiving, based on the control information, a downlink data payload of the second message.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to transmit a first message of a RACH procedure over a random access resource, identify a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitor for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, decode control information of the second message based on an identifier associated with the random access resource, and receive, based on the control information, a downlink data payload of the second message.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for transmitting a first message of a RACH procedure over a random access resource, identifying a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitoring for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, decoding control information of the second message based on an identifier associated with the random access resource, and receiving, based on the control information, a downlink data payload of the second message.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to transmit a first message of a RACH procedure over a random access resource, identify a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitor for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, decode control information of the second message based on an identifier associated with the random access resource, and receive, based on the control information, a downlink data payload of the second message.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first set of resources includes a first control resource set and the second set of resources includes a second control resource set.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first set of resources includes a first random access response window and the second set of resources includes a second random access response window that may be non-overlapping with the first random access response window.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the configuration may include operations, features, means, or instructions for receiving a message indicating the configuration. In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the configuration may be predetermined.

A method of wireless communications at a UE is described. The method may include transmitting a first message of a RACH procedure over a random access resource, identifying a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitoring for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, identifying an offset for an identifier associated with the random access resource, decoding control information of the second message based on the identifier and the offset, and receiving, based on the control information, a downlink data payload of the second message.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to transmit a first message of a RACH procedure over a random access resource, identify a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitor for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, identify an offset for an identifier associated with the random access resource, decode control information of the second message based on the identifier and the offset, and receive, based on the control information, a downlink data payload of the second message.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for transmitting a first message of a RACH procedure over a random access resource, identifying a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitoring for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, identifying an offset for an identifier associated with the random access resource, decoding control information of the second message based on the identifier and the offset, and receiving, based on the control information, a downlink data payload of the second message.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to transmit a first message of a RACH procedure over a random access resource, identify a configuration including a first set of resources associated with a second message of a two-step RACH procedure and a second set of resources associated with a second message of a four-step RACH procedure, monitor for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, identify an offset for an identifier associated with the random access resource, decode control information of the second message based on the identifier and the offset, and receive, based on the control information, a downlink data payload of the second message.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the offset includes a first offset associated with the two-step RACH procedure or a second offset associated with the four-step RACH procedure.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first set of resources includes a control resource set and a first random access response window and the second set of resources includes the control resource set and a second random access response window that may be at least partially overlapping with the first random access response window.

A method of wireless communications at a base station is described. The method may include receiving a first message of a two-step RACH procedure in a cell, the first message including a preamble sequence and a scrambled data payload, identifying resources of the first message, determining a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources, and descrambling the scrambled data payload using the descrambling sequence.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive a first message of a two-step RACH procedure in a cell, the first message including a preamble sequence and a scrambled data payload, identify resources of the first message, determine a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources, and descramble the scrambled data payload using the descrambling sequence.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for receiving a first message of a two-step RACH procedure in a cell, the first message including a preamble sequence and a scrambled data payload, identifying resources of the first message, determining a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources, and descrambling the scrambled data payload using the descrambling sequence.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to receive a first message of a two-step RACH procedure in a cell, the first message including a preamble sequence and a scrambled data payload, identify resources of the first message, determine a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources, and descramble the scrambled data payload using the descrambling sequence.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for configuring a set of message identifiers for the cell, transmitting a broadcast message indicating an association between each of the set of message identifiers and a respective preamble sequence index, and determining the descrambling sequence based on a message identifier of the set of message identifiers associated with the preamble sequence.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the broadcast message includes a system information message broadcast. Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining a configuration of one or more cell-specific parameters, and transmitting a message indicating the configuration of the one or more cell-specific parameters.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining a configuration of an association between the scrambling sequence and one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting a broadcast message indicating the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the one or more cell-specific parameters, and an index of the preamble sequence may be predetermined.

A method of wireless communications at a base station is described. The method may include receiving a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, encoding, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step RACH procedure, generating, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message, scrambling the downlink data payload using the scrambling sequence, and transmitting, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, encode, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step RACH procedure, generate, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message, scramble the downlink data payload using the scrambling sequence, and transmit, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for receiving a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, encoding, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step RACH procedure, generating, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message, scrambling the downlink data payload using the scrambling sequence, and transmitting, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to receive a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, encode, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step RACH procedure, generate, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message, scramble the downlink data payload using the scrambling sequence, and transmit, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining that the downlink data payload may be associated with a UE of the one or more UEs, and transmitting information within the downlink data payload that indicates the downlink data payload may be associated with the UE.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the information within the downlink data payload includes a medium access control (MAC) control element indicating an identifier of the UE.

A method of wireless communications at a base station is described. The method may include receiving a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, encoding, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step RACH procedure, generating, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message, scrambling the downlink data payload using the scrambling sequence, and transmitting, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, encode, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step RACH procedure, generate, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message, scramble the downlink data payload using the scrambling sequence, and transmit, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for receiving a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, encoding, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step RACH procedure, generating, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message, scrambling the downlink data payload using the scrambling sequence, and transmitting, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to receive a first message of a two-step RACH procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, encode, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step RACH procedure, generate, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message, scramble the downlink data payload using the scrambling sequence, and transmit, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the identifier associated with the first message includes an identifier of the UE.

A method of wireless communications at a base station is described. The method may include identifying a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receiving a first message of a RACH procedure over a random access resource, encoding control information based on an identifier associated with the random access resource, and transmitting a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receive a first message of a RACH procedure over a random access resource, encode control information based on an identifier associated with the random access resource, and transmit a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for identifying a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receiving a first message of a RACH procedure over a random access resource, encoding control information based on an identifier associated with the random access resource, and transmitting a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to identify a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receive a first message of a RACH procedure over a random access resource, encode control information based on an identifier associated with the random access resource, and transmit a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting, to one or more UEs, a message indicating the configuration.

A method of wireless communications at a base station is described. The method may include identifying a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receiving a first message of a RACH procedure over a random access resource, determining an offset for the identifier associated with the random access resource, encoding control information based on the offset and the identifier associated with the random access resource, and transmitting a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receive a first message of a RACH procedure over a random access resource, determine an offset for the identifier associated with the random access resource, encode control information based on the offset and the identifier associated with the random access resource, and transmit a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for identifying a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receiving a first message of a RACH procedure over a random access resource, determining an offset for the identifier associated with the random access resource, encoding control information based on the offset and the identifier associated with the random access resource, and transmitting a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to identify a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure, receive a first message of a RACH procedure over a random access resource, determine an offset for the identifier associated with the random access resource, encode control information based on the offset and the identifier associated with the random access resource, and transmit a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communications that supports radio network temporary identifiers (RNTIs) and scrambling for two-step random access channel (RACH) procedures in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIGs. 3 through 5 illustrate examples of a process flow in a system that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIGs. 6 and 7 show block diagrams of devices that support RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIG. 8 shows a block diagram of a random access manager that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIG. 9 shows a diagram of a system including a device that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIGs. 10 and 11 show block diagrams of devices that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIG. 12 shows a block diagram of a random access manager that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIG. 13 shows a diagram of a system including a device that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

FIGs. 14 through 23 show flowcharts illustrating methods that supports RNTIs and scrambling for two-step RACH procedures in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Some wireless communications systems may support various random access channel (RACH) procedures for communications between a user equipment (UE) and a base station. The RACH procedures may enable initial access to a cell, connection re-establishment, handover procedures, and synchronization on a channel. In any case, the random access procedures may include a series of handshake messages exchanged between the UE and the base station, where each message may provide each device with information associated with subsequent messages.

As an example, a UE and base station may establish communications using a four-step RACH procedure. In a four-step RACH procedure, a UE may initiate the procedure through the transmission of a first message (e.g., Msg1) including a random access preamble carried on a physical random access channel (PRACH) . Upon detecting the preamble in the first message, the base station may respond to the UE with a second message (e.g., Msg2) , which may be referred to as a random access response (RAR) . The RAR may be transmitted on a downlink shared channel (DL SCH) that includes information enabling the UE to establish communications with the base station. This information includes, for example, an index of the detected preamble sequence, an uplink timing correction for the UE, a scheduling grant indicating a set of resource the UE may use for transmitting a subsequent uplink message, and an identifier (e.g., a temporary cell-radio network temporary identifier (TC-RNTI) ) .

The UE may receive the second message and, as a third step of the four-step RACH procedure, transmit a third message (e.g., Msg3) including device identification information to the base station. For example, the UE may transmit the third message including at least a UE identity using uplink (UL) shared channel (SCH) resources assigned by the base station and indicated by the scheduling grant of the second message. The UE may also scramble a payload of the third message (e.g., sent over a physical uplink shared channel (PUSCH) ) using scrambling based on the TC-RNTI received in the second message. The four-step RACH procedure may conclude with the transmission of a fourth message (e.g., Msg4) that provides contention resolution. For instance, two or more UEs may transmit respective messages corresponding to Msg3 at the same time, resulting in a collision, and the fourth message may provide a particular UE identifier to indicate which UE is associated with downlink data transmitted by the base station. The corresponding UE may then determine that the RACH procedure was successful.

Additionally or alternatively, a UE and a base station may establish communication using a two-step RACH procedure, which may utilize a reduced number of messages exchanged (e.g., as compared to the four-step RACH procedure described above) . For instance, a UE may initiate a two-step RACH procedure by transmitting a first message (e.g., MsgA) that includes a preamble sequence and a data payload carried by a PUSCH. The contents of MsgA of the two-step RACH procedure may include similar information as the first and third messages (Msg1 and Msg3) of the four-step RACH procedure described above. In response to MsgA, the base station may transmit a second message of the two-step RACH procedure, which may include a PDCCH and PDSCH carrying a downlink data payload. This second message of the two-step RACH procedure may include similar information as the second and fourth (Msg 2 and Msg4) of the four-step RACH procedure.

In some cases, resources may be allocated for different RACH procedures that are supported by the system, where a RACH occasion (e.g., time/frequency resources) may be shared, for example, between two-step RACH procedures and four-step RACH procedures. Additionally, some UEs may be capable of performing two-step RACH procedures, four-step RACH procedures, or both. However, as a result of the shared resources between different types of RACH procedures, additional configurations of handshake messages may be desired to maintain efficiency in the system when the RACH procedures coexist and used the same RACH occasions. For instance, scrambling sequence configurations may be desired to allow a UE to encode a data payload of MsgA of the two-step RACH procedure, while also enabling a base station to decode the uplink data payload. Configurations for identifiers and scrambling sequences for MsgB may likewise provide for efficiency in the system when RACH occasions are shared. Further, techniques that prevent ambiguity in downlink control channel reception at the UE may also be desired.

As an example, data scrambling may be used to provide inter-cell interference randomization when different scrambling sequences are used among neighboring cells. As mentioned above, in four-step RACH procedures, the scrambling of a PUSCH payload (sent via the third message) may be based on the TC-RNTI provided by the base station in Msg2. In two-step RACH procedures, however, there may not be a configured RNTI (e.g., configured via higher-layers) available for the UE to scramble a payload of MsgA. Moreover, if the UE were to autonomously determine a data scrambling sequence for MsgA, the sequence selected by the UE may not be known to the base station, thereby preventing the base station from decoding the contents of MsgA when received. Moreover, in four-step RACH procedures, a PDCCH in Msg2 may be addressed to a random access RNTI (RA-RNTI) that identifies the time/frequency resources on which the preamble sequence was transmitted/detected and may also be used to generate the scrambling sequence for a downlink data payload of Msg2. If the same approach is used for MsgB of the two-step RACH procedure, multiple UEs that collide when selecting the same RACH occasion may receive the same MsgB, which may complicate contention resolution.

Further, there may be ambiguity in the reception of PDCCH when two-step RACH procedures and four-step RACH procedures share RACH occasions. As an example, in four-step RACH procedures, a PDCCH that scheduled the PDSCH including the payload of Msg2 may be received within a RAR window following the transmission of Msg1. However, ambiguity may exist for respective UEs performing two-step RACH procedures and four-step RACH procedures, where there may be an unclear interpretation of a received PDCCH with shared RACH occasions. For example, a UE performing a two-step RACH procedure may detect a PDCCH for a four-step RACH procedure, and may inadvertently determine a RACH failure when the UE is unable to identify its UE identifier in the corresponding PDSCH.

As described herein, various techniques may be used to specify scrambling sequences for MsgA transmissions. For example, the data scrambling of MsgA for a two-step RACH procedure may be associated at least with a preamble index used by the UE. For example, a set of identifiers for MsgA (e.g., a set of MsgA-RNTIs) may be configured by a network, and in some cases, the set of MsgA-RNTIs and an association with preamble indexes may be broadcasted from a base station to one or more UEs. The scrambling sequence for the payload of the PUSCH included in MsgA may then be determined based on the MsgA-RNTI selected by the UE as well as the associated time/frequency resource index for preamble transmissions (e.g., associated with the RA-RNTI or the RACH occasion) . Additionally or alternatively, the scrambling sequence for the PUSCH sent via MsgA may be determined based on an index of the preamble selected by the UE, cell-specific parameters (e.g., a physical cell identifier) , as well as the associated time/frequency resources used to transmit the preamble. In some cases, an association between the scrambling sequence, preamble indexes, cell-specific parameter (s) , and time/frequency resources for preamble transmissions may be predetermined or may be configured by the network and indicated by a base station to one or more UEs.

In other aspects, the described techniques may provide for RNTI and data scrambling sequences for MsgB of the two-step RACH procedure, which may be based on an identifier associated with the resources for MsgA or an identifier of the UE. For instance, an identifier associated with MsgB (e.g., a MsgB-RNTI) may be used by a base station for MsgB transmissions, where the MsgB-RNTI may be determined based on an identifier associated with time/frequency resources of the RACH occasion for the transmission of MsgA. Further, the MsgB-RNTI may be used to generate the data scrambling sequence for the downlink data payload of the PDSCH scheduled by the PDCCH of MsgB. In other examples, the MsgB-RNTI may be determined based on a UE identifier included in MsgA, such as a UE identity (UE ID) (or a portion of the UE ID) . The UE identifier may also include the identifier associated with the transmission of MsgA (e.g., a MsgA-RNTI) . Data scrambling for a downlink data payload of the PDSCH transmitted using MsgB may thus be based on the MsgB-RNTI and the preamble index associated with MsgB. As a result, the MsgB-RNTI may enable a dedicated MsgB to be transmitted for each received preamble and/or UE. Further the UE identifier used for the generation of the MsgB-RNTI may provide for conflict resolution for UEs receiving a same MsgB.

To resolve the ambiguity of PDCCHs corresponding to respective RACH procedures, a network may also configure different resources for different types of RACH procedures that share RACH occasions. For instance, different control resource sets (CORESETs) and/or search spaces may be configured for different types of RACH procedures, and the same equation may be used to identify the respective identifier for different types of RACH procedures (e.g., RA-RNTI for four-step RACH procedures and the MsgB-RNTI for two-step RACH procedures) . In a second example, a base station may configure a same CORESET/search space for both two-step RACH and four-step RACH procedures, but using different, non-overlapping, RAR windows for two-step RACH and four-step RACH procedures. Identical equations may again be used to identify the RA-RNTI for the four-step RACH procedure and the MsgB-RNTI for the two-step RACH procedure. Additionally or alternatively, the PDCCH ambiguity may be avoided through the configuration of an offset in an identifier associated with the resources used for transmitting a first message of a RACH procedure. For example, a MsgB-RNTI for a two-step RACH procedure may include an offset that is used to distinguish PDCCH (and PDSCH) received for two-step RACH procedures from PDCCH (and PDSCH) received for four-step RACH procedures.

Aspects of the disclosure are initially described in the context of a wireless communications system. Additional aspects of the disclosure are then described with reference to process flows in a system that supports shared RACH opportunities between different RACH procedures. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to jumbo radio resource control message delivery.

FIG. 1 illustrates an example of a wireless communications system 100 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The wireless communications system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some cases, wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices. Wireless communications system 100 supports the use of various configurations of RNTIs and scrambling sequences for handshake messages of a two-step RACH procedures that provide efficiency to systems that enable sharing of RACH occasions between different RACH procedures. Wireless communications system 100 further supports the use of respective resource configuration for different types of RACH procedures.

Base stations 105 may wirelessly communicate with UEs 115 via one or more base station antennas. Base stations 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next-generation NodeB or giga-NodeB (either of which may be referred to as a gNB) , a Home NodeB, a Home eNodeB, or some other suitable terminology. Wireless communications system 100 may include base stations 105 of different types (e.g., macro or small cell base stations) . The UEs 115 described herein may be able to communicate with various types of base stations 105 and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like.

Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 is supported. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via communication links 125, and communication links 125 between a base station 105 and a UE 115 may utilize one or more carriers. Communication links 125 shown in wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Downlink transmissions may also be called forward link transmissions while uplink transmissions may also be called reverse link transmissions.

The geographic coverage area 110 for a base station 105 may be divided into sectors making up a portion of the geographic coverage area 110, and each sector may be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other types of cells, or various combinations thereof. In some examples, a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used for communication with a base station 105 (e.g., over a carrier) , and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID) , a virtual cell identifier (VCID) ) operating via the same or a different carrier. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine-type communication (MTC) , narrowband Internet-of-Things (NB-IoT) , enhanced mobile broadband (eMBB) , or others) that may provide access for different types of devices. In some cases, the term “cell” may refer to a portion of a geographic coverage area 110 (e.g., a sector) over which the logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system 100, and each UE 115 may be stationary or mobile. A UE 115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client. A UE 115 may also be a personal electronic device such as a cellular phone, a personal digital assistant (PDA) , a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 may also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or an MTC device, or the like, which may be implemented in various articles such as appliances, vehicles, meters, or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices, and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program that can make use of the information or present the information to humans interacting with the program or application. Some UEs 115 may be designed to collect information or enable automated behavior of machines. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously) . In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power saving “deep sleep” mode when not engaging in active communications, or operating over a limited bandwidth (e.g., according to narrowband communications) . In some cases, UEs 115 may be designed to support critical functions (e.g., mission critical functions) , and a wireless communications system 100 may be configured to provide ultra-reliable communications for these functions.

In some cases, a UE 115 may also be able to communicate directly with other UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device (D2D) protocol) . One or more of a group of UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105, or be otherwise unable to receive transmissions from a base station 105. In some cases, groups of UEs 115 communicating via D2D communications may utilize a one-to-many (1: M) system in which each UE 115 transmits to every other UE 115 in the group. In some cases, a base station 105 facilitates the scheduling of resources for D2D communications. In other cases, D2D communications are carried out between UEs 115 without the involvement of a base station 105.

Base stations 105 may communicate with the core network 130 and with one another. For example, base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., via an S1, N2, N3, or other interface) . Base stations 105 may communicate with one another over backhaul links 134 (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130) .

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) , which may include at least one mobility management entity (MME) , at least one serving gateway (S-GW) , and at least one Packet Data Network (PDN) gateway (P-GW) . The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transferred through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to the network operators IP services. The operators IP services may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched (PS) Streaming Service.

At least some of the network devices, such as a base station 105, may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC) . Each access network entity may communicate with UEs 115 through a number of other access network transmission entities, which may be referred to as a radio head, a smart radio head, or a transmission/reception point (TRP) . In some configurations, various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station 105) .

Wireless communications system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz) . Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features. However, the waves may penetrate structures sufficiently for a macro cell to provide service to UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter range (e.g., less than 100 km) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band. The SHF region includes bands such as the 5 GHz industrial, scientific, and medical (ISM) bands, which may be used opportunistically by devices that may be capable of tolerating interference from other users.

Wireless communications system 100 may also operate in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) , also known as the millimeter band. In some examples, wireless communications system 100 may support millimeter wave (mmW) communications between UEs 115 and base stations 105, and EHF antennas of the respective devices may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a UE 115. However, the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. Techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

In some cases, wireless communications system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, wireless communications system 100 may employ License Assisted Access (LAA) , LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5 GHz ISM band. When operating in unlicensed radio frequency spectrum bands, wireless devices such as base stations 105 and UEs 115 may employ listen-before-talk (LBT) procedures to ensure a frequency channel is clear before transmitting data. In some cases, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA) . Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD) , time division duplexing (TDD) , or a combination of both.

In some examples, base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, wireless communications system 100 may use a transmission scheme between a transmitting device (e.g., a base station 105) and a receiving device (e.g., a UE 115) , where the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communications may employ multipath signal propagation to increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream, and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO) where multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or steer an antenna beam (e.g., a transmit beam or receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying certain amplitude and phase offsets to signals carried via each of the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation) .

In one example, a base station 105 may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE 115. For instance, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station 105 multiple times in different directions, which may include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by the base station 105 or a receiving device, such as a UE 115) a beam direction for subsequent transmission and/or reception by the base station 105.

Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station 105 in a single beam direction (e.g., a direction associated with the receiving device, such as a UE 115) . In some examples, the beam direction associated with transmissions along a single beam direction may be determined based at least in in part on a signal that was transmitted in different beam directions. For example, a UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions, and the UE 115 may report to the base station 105 an indication of the signal it received with a highest signal quality, or an otherwise acceptable signal quality. Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105, a UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115) , or transmitting a signal in a single direction (e.g., for transmitting data to a receiving device) .

A receiving device (e.g., a UE 115, which may be an example of a mmW receiving device) may try multiple receive beams when receiving various signals from the base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive beams or receive directions. In some examples, a receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving a data signal) . The single receive beam may be aligned in a beam direction determined based at least in part on listening according to different receive beam directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio, or otherwise acceptable signal quality based at least in part on listening according to multiple beam directions) .

In some cases, the antennas of a base station 105 or UE 115 may be located within one or more antenna arrays, which may support MIMO operations, or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some cases, antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

In some cases, wireless communications system 100 may be a packet-based network that operate according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or core network 130 supporting radio bearers for user plane data. At the Physical layer, transport channels may be mapped to physical channels.

In some cases, UEs 115 and base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. HARQ feedback is one technique of increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC) ) , forward error correction (FEC) , and retransmission (e.g., automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., signal-to-noise conditions) . In some cases, a wireless device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

Time intervals in LTE or NR may be expressed in multiples of a basic time unit, which may, for example, refer to a sampling period of T _s = 1/30,720,000 seconds. Time intervals of a communications resource may be organized according to radio frames each having a duration of 10 milliseconds (ms) , where the frame period may be expressed as T _f = 307,200 T _s. The radio frames may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots each having a duration of 0.5 ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period) . Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the smallest scheduling unit of the wireless communications system 100, and may be referred to as a transmission time interval (TTI) . In other cases, a smallest scheduling unit of the wireless communications system 100 may be shorter than a subframe or may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) or in selected component carriers using sTTIs) .

In some wireless communications systems, a slot may further be divided into multiple mini-slots containing one or more symbols. In some instances, a symbol of a mini-slot or a mini-slot may be the smallest unit of scheduling. Each symbol may vary in duration depending on the subcarrier spacing or frequency band of operation, for example. Further, some wireless communications systems may implement slot aggregation in which multiple slots or mini-slots are aggregated together and used for communication between a UE 115 and a base station 105.

The term “carrier” refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over a communication link 125. For example, a carrier of a communication link 125 may include a portion of a radio frequency spectrum band that is operated according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a pre-defined frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN) ) , and may be positioned according to a channel raster for discovery by UEs 115. Carriers may be downlink or uplink (e.g., in an FDD mode) , or be configured to carry downlink and uplink communications (e.g., in a TDD mode) . In some examples, signal waveforms transmitted over a carrier may be made up of multiple sub-carriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) .

The organizational structure of the carriers may be different for different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR) . For example, communications over a carrier may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling to support decoding the user data. A carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc. ) , and control signaling that coordinates operation for the carrier. In some examples (e.g., in a carrier aggregation configuration) , a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers.

Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, control information transmitted in a physical control channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces) .

A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example, the carrier bandwidth may be one of a number of predetermined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz) . In some examples, each served UE 115 may be configured for operating over portions or all of the carrier bandwidth. In other examples, some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a predefined portion or range (e.g., set of subcarriers or RBs) within a carrier (e.g., “in-band” deployment of a narrowband protocol type) .

In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme) . Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. In MIMO systems, a wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers) , and the use of multiple spatial layers may further increase the data rate for communications with a UE 115.

Devices of the wireless communications system 100 (e.g., base stations 105 or UEs 115) may have a hardware configuration that supports communications over a particular carrier bandwidth, or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include base stations 105 and/or UEs 115 that support simultaneous communications via carriers associated with more than one different carrier bandwidth.

Wireless communications system 100 may support communication with a UE 115 on multiple cells or carriers, a feature which may be referred to as carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both FDD and TDD component carriers.

In some cases, wireless communications system 100 may utilize enhanced component carriers (eCCs) . An eCC may be characterized by one or more features including wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or modified control channel configuration. In some cases, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have a suboptimal or non-ideal backhaul link) . An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum) . An eCC characterized by wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are not capable of monitoring the whole carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power) .

In some cases, an eCC may utilize a different symbol duration than other component carriers, which may include use of a reduced symbol duration as compared with symbol durations of the other component carriers. A shorter symbol duration may be associated with increased spacing between adjacent subcarriers. A device, such as a UE 115 or base station 105, utilizing eCCs may transmit wideband signals (e.g., according to frequency channel or carrier bandwidths of 20, 40, 60, 80 MHz, etc. ) at reduced symbol durations (e.g., 16.67 microseconds) . A TTI in eCC may consist of one or multiple symbol periods. In some cases, the TTI duration (that is, the number of symbol periods in a TTI) may be variable.

Wireless communications system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed spectrum bands, among others. The flexibility of eCC symbol duration and subcarrier spacing may allow for the use of eCC across multiple spectrums. In some examples, NR shared spectrum may increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across the frequency domain) and horizontal (e.g., across the time domain) sharing of resources.

PUCCH may be mapped to a control channel defined by a code and two consecutive resource blocks. Uplink control signaling may depend on the presence of timing synchronization for a cell. PUCCH resources for scheduling request (SR) and channel quality indicator (CQI) reporting may be assigned (and revoked) through RRC signaling. In some cases, resources for SR may be assigned after acquiring synchronization through a RACH procedure. In other cases, an SR may not be assigned to a UE 115 through the RACH (i.e., synchronized UEs may or may not have a dedicated SR channel) . PUCCH resources for SR and CQI may be lost when the UE is no longer synchronized.

PDCCH carries downlink control information (DCI) in control channel elements (CCEs) , which may consist of nine logically contiguous resource element groups (REGs) , where each REG contains 4 resource elements (REs) . DCI includes information regarding DL scheduling assignments, uplink resource grants, transmission scheme, uplink power control, HARQ information, a modulation and coding scheme (MCS) . and other information. The size and format of the DCI messages can differ depending on the type and amount of information that is carried by the DCI. For example, if spatial multiplexing is supported, the size of the DCI message is large compared to contiguous frequency allocations. Similarly, for a system that employs MIMO, the DCI must include additional signaling information. DCI size and format depend on the amount of information as well as factors such as bandwidth, the number of antenna ports, and duplexing mode.

A physical downlink control channel (PDCCH) may carry DCI messages associated with multiple users, and each UE 115 may decode the DCI messages that are intended for it. For example, each UE 115 may be assigned a C-RNTI and CRC bits attached to each DCI may be scrambled based on the C-RNTI. To reduce power consumption and overhead at the user equipment, a limited set of CCE locations can be specified for DCI associated with a specific UE 115. CCEs may be grouped (e.g., in groups of 1, 2, 4 and 8 CCEs) , and a set of CCE locations in which the user equipment may find relevant DCI may be specified. These CCEs may be known as a search space. The search space can be partitioned into two regions: a common CCE region or search space and a UE-specific (dedicated) CCE region or search space. The common CCE region is monitored by all UEs served by a base station 105 and may include information such as paging information, system information, random access procedures and the like. The UE-specific search space may include user-specific control information. CCEs may be indexed, and the common search space may start from CCE 0. The starting index for a UE specific search space depends on the C-RNTI, the subframe index, the CCE aggregation level and a random seed. A UE 115 may attempt to decode DCI by performing a process known as a blind decode, during which search spaces are randomly decoded until the DCI is detected. During a blind decode, the UE 115 may attempt descramble all potential DCI messages using its C-RNTI, and perform a CRC check to determine whether the attempt was successful. In some cases, HARQ feedback may be transmitted in response to a received PDCCH.

A UE 115 attempting to access a wireless network may perform an initial cell search by detecting a primary synchronization signal (PSS) from a base station 105. The PSS may enable synchronization of slot timing and may indicate a physical layer identity value. The UE 115 may then receive a secondary synchronization signal (SSS) . The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The SSS may also enable detection of a duplexing mode and a cyclic prefix length. Some systems, such as TDD systems, may transmit an SSS but not a PSS. Both the PSS and the SSS may be located in the central 62 and 72 subcarriers of a carrier, respectively. In some cases, a base station 105 may transmit synchronization signals (e.g., PSS SSS, and the like) using multiple beams in a beam-sweeping manner through a cell coverage area. In some cases, PSS, SSS, and/or broadcast information (e.g., a physical broadcast channel (PBCH) ) may be transmitted within different synchronization signal (SS) blocks on respective directional beams, where one or more SS blocks may be included within an SS burst.

After receiving the PSS and SSS, the UE 115 may receive an MIB, which may be transmitted in the PBCH. The MIB may contain system bandwidth information, an SFN, and a PHICH configuration. After decoding the MIB, the UE 115 may receive one or more SIBs. For example, SIB1 may contain cell access parameters and scheduling information for other SIBs. Decoding SIB1 may enable the UE 115 to receive SIB2. SIB2 may contain RRC configuration information related to RACH procedures, paging, PUCCH, PUSCH, power control, SRS, and cell barring.

After completing initial cell synchronization, a UE 115 may decode the MIB, SIB1 and SIB2 prior to accessing the network. The MIB may be transmitted on PBCH and may utilize the first 4 OFDMA symbols of the second slot of the first subframe of each radio frame. It may use the middle 6 RBs (72 subcarriers) in the frequency domain. The MIB carries a few important pieces of information for UE initial access, including: DL channel bandwidth in term of RBs, PHICH configuration (duration and resource assignment) , and SFN. A new MIB may be broadcast every fourth radio frame (SFN mod 4 = 0) at and rebroadcast every frame (10ms) . Each repetition is scrambled with a different scrambling code.

After reading a MIB (either a new version or a copy) , the UE 115 may can try different phases of a scrambling code until it gets a successful CRC check. The phase of the scrambling code (0, 1, 2 or 3) may enable the UE 115 to identify which of the four repetitions has been received. Thus, the UE 115 may determine the current SFN by reading the SFN in the decoded transmission and adding the scrambling code phase. After receiving the MIB, a UE may receive one or more SIBs. Different SIBs may be defined according to the type of system information conveyed. A new SIB1 may be transmitted in the fifth subframe of every eighth frame (SFN mod 8 = 0) and rebroadcast every other frame (20ms) . SIB1 includes access information, including cell identity information, and it may indicate whether a UE is allowed to camp on a cell. SIB1 also includes cell selection information (or cell selection parameters) . Additionally, SIB1 includes scheduling information for other SIBs. SIB2 may be scheduled dynamically according to information in SIB1, and includes access information and parameters related to common and shared channels. The periodicity of SIB2 can be set to 8, 16, 32, 64, 128, 256 or 512 radio frames.

After the UE 115 decodes SIB2, it may transmit a RACH preamble to a base station 105. For example, the RACH preamble may be randomly selected from a set of 64 predetermined sequences. This may enable the base station 105 to distinguish between multiple UEs 115 trying to access the system simultaneously. The base station 105 may respond with a random access response that provides an uplink resource grant, a timing advance, and a temporary C-RNTI. The UE 115 may then transmit an RRC connection request along with a TMSI (if the UE 115 has previously been connected to the same wireless network) or a random identifier. The RRC connection request may also indicate the reason the UE 115 is connecting to the network (e.g., emergency, signaling, data exchange, etc. ) . The base station 105 may respond to the connection request with a contention resolution message addressed to the UE 115, which may provide a new C-RNTI. If the UE 115 receives a contention resolution message with the correct identification, it may proceed with RRC setup. If the UE 115 does not receive a contention resolution message (e.g., if there is a conflict with another UE 115) it may repeat the RACH procedure by transmitting a new RACH preamble. Such exchange of messages between the UE 115 and base station 105 for random access may be referred to as a four-step RACH procedure.

In other examples, a two-step RACH procedure may be performed for random access. For instance, wireless devices operating in licensed or unlicensed spectrum within wireless communications system 100 may initiate a two-step RACH procedure to reduce delay in establishing communication with a base station 105 (e.g., as compared to a four-step RACH procedure) . In some cases, the two-step RACH procedure may operate regardless of whether a wireless device (e.g., a UE 115) has a valid TA. For example, a UE 115 may use a valid TA to coordinate the timing of its transmissions to a base station 105 (e.g., to account for propagation delay) and may receive the valid TA as part of the two-step RACH procedure. Additionally, the two-step RACH procedure may be applicable to any cell size, may work regardless of whether the RACH procedure is contention-based or contention-free, and may combine multiple RACH messages from a four-step RACH procedure.

Wireless communications system 100 may support shared RACH occasions for different types of RACH procedures. For instance, a two-step RACH procedure and a four-step RACH procedure may be configured with shared RACH occasions (e.g., time/frequency resources) . As a result, various scrambling sequences and identifiers (e.g., RNTIs) may be used for two-step RACH procedures, where the scrambling sequences may enable a UE 115 and a base station 105 to properly identify a payload carried within the different handshake messages of the RACH procedure. Further, the RNTIs associated with the handshake messages may enable contention resolution for UEs 115 that transmitted a preamble at the same time.

In one example, a UE 115 may identify a scrambling sequence based on a message identifier associated with a preamble index, information associated with a cell (e.g., cell-specific parameters such as a cell identifier) and an identifier associated with time/frequency resources used for transmitting the preamble in a first message of the two-step RACH procedure (e.g., a random access RNTI (RA-RNTI) ) . The determined scrambling sequence may be used for scrambling a payload of the first message sent to a base station 105. In some cases, an association between each of a set of message identifiers, a preamble index, a scrambling sequence, cell-specific parameters, or a combination thereof, may be configured by a network and indicated by a base station 105 through broadcast signaling. Additionally, a message identifier and a scrambling sequence for a second message of the two-step RACH procedures may be based on the identifier associated with the time/frequency resources used for transmitting the preamble or a UE identifier in the first message. In such cases, a downlink data payload of the second message may be scrambled using the message identifier for the second message, and a UE 115 may determine that the downlink data payload belongs to the UE 115 based on either the contents of the payload or the UE identifier used to generate the scrambling sequence.

In some cases, respective sets of resources may be configured for different types of RACH procedures that share RACH occasions. As an example, different CORESETs and/or search spaces or different random access response windows may be configured for two-step RACH procedures and four-step RACH procedures. These different resources may be used to distinguish between downlink information sent to a UE 115 for the respective RACH procedures sharing RACH occasions, while both RACH procedures may use the same equation for generating an identifier for downlink messages. In other examples, the same CORESETS and at least partially overlapping random access response windows may be configured for both types of RACH procedures, while an offset included in a message identifier (e.g., for two-step RACH) may provide the differentiation in downlink messages sent to a UE 115.

FIG. 2 illustrates an example of a wireless communications system 200 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. In some examples, wireless communications system 200 may implement aspects of wireless communications system 100.

Wireless communications system 200 may support various RACH procedures for communications between a UE 115 (e.g., including UE 115-a and UE 115-b) and base station 105-a. The RACH procedures may enable initial access to a cell, connection re-establishment, handover procedures, and synchronization on a channel. In any case, the random access procedures may include a series of handshake messages exchanged between the UE 115 and base station 105-a, where each message may provide each device with information associated with subsequent messages.

As an example, UE 115-a and base station 105-a may establish communications using a four-step RACH procedure. In a four-step RACH procedure, UE 115-a may initiate the procedure through the transmission of a first message (e.g., Msg1 205) including a random access preamble 212 carried on a physical random access channel (PRACH) . The preamble 212 may be a sequence-based preamble (e.g., based on a Zadoff-Chu sequence) and may indicate the random access attempt by UE 115-a. The preamble 212 may also enable base station 105-a to estimate a timing delay between UE 115-a and base station 105-a.

Upon detecting the preamble 212 in the first message 205, base station 105-a may respond to UE 115-a with a second message (e.g., Msg2 210) , which may be referred to as a RAR. The RAR may be transmitted on a DL SCH that includes information enabling UE 115-a to establish communications with base station 105-a. This information includes, for example, an index of the detected preamble 212, an uplink timing correction for UE 115-a, a scheduling grant indicating a set of resources UE 115-a may use for transmitting a subsequent uplink message, and an identifier (e.g., a TC-RNTI) . This identifier may be used for subsequent communications between UE 115-a and base station 105-a, and may be used for scrambling of additional messages in the RACH procedure and any retransmissions from UE 115-a. The RAR scheduled on the DL SCH may be indicated by a PDCCH using an identifier (e.g., a RA-RNTI) , where the identifier may be associated with the time/frequency resources used for the transmission of the preamble 212 by UE 115-a (e.g., a RACH occasion) . As an example, base station 105-a may scramble cyclic redundancy check (CRC) bits of the PDCCH using the RA-RNTI, where the PDCCH is associated with the transmission of a PDSCH carrying the RAR.

UE 115-a may receive the second message 210 and, as a third step of the four-step RACH procedure, transmit a third message 215 (e.g., Msg3) including device identification information to base station 105-a. For example, UE 115-a may transmit the third message 215 including at least a UE identity using UL SCH resources assigned by base station 105-a and indicated by the scheduling grant of the second message. As mentioned above, UE 115-a may scramble the payload of the third message (e.g., sent over a PUSCH) using UE-specific scrambling based on the TC-RNTI received in the second message. Alternatively, such as when UE 115-a is in an RRC connected state, UE 115-a may have already been assigned a C-RNTI, and the C-RNTI may be used as the UE identifier. In other cases, a core-network device identifier, such as an S-temporary mobile subscriber identity (S-TMSI) or a random value, may be used as the UE identifier.

The four-step RACH procedure may conclude with the transmission of a fourth message 220 (e.g., Msg4) that provides contention resolution information. For instance, contention by multiple UEs 115 may be possible in the third step, where each UE 115 may have simultaneously transmitted the same random access preamble and therefore also received the same RAR from base station 105-a. As a result, two or more UEs 115 may transmit respective messages (e.g., corresponding to Msg3) including device information at the same time, resulting in a collision. For contention resolution, if UE 115-a already has a C-RNTI assigned (e.g., is not using a TC-RNTI) , then UE 115-a may be addressed on a PDCCH using the C-RNTI associated with UE 115-a. Alternatively, if UE 115-a does not have a valid C-RNTI (e.g., because UE 115-a was in an RRC idle state) , the contention resolution message may be addressed using the TC-RNTI for UE 115-a. UE 115-a may then compare the identifier received on the DL SCH with the identifier transmitted in the third message, and may determine that the identifiers match based on the comparison. As a result, UE 115-a may determine that the RACH procedure was successful, in which case the TC-RNTI is promoted to a C-RNTI.

Additionally or alternatively, a UE 115 and base station 105-a may establish communication using a two-step RACH procedure, which may utilize a reduced number of messages exchanged (e.g., as compared to the four-step RACH procedure) . As such, two-step RACH procedures may minimize delays in establishing communications, while transmitting the same information included in other RACH procedures. For instance, UE 115-b may initiate a two-step RACH procedure by transmitting a first message (e.g., MsgA 225) that includes a preamble sequence 227 and a data payload carried by a PUSCH 229. The contents of MsgA 225 of the two-step RACH procedure may include similar information of the first message 205 and third message 215 (Msg1 and Msg3) of the four-step RACH procedure described above.

In response to MsgA 225, base station 105-a may transmit a second message (e.g., MsgB 230) of the two-step RACH procedure, which may include a PDCCH 232 and PDSCH 234 carrying a downlink data payload. MsgB 230 of the two-step RACH procedure may include similar information as the second message 210 and the fourth message 220 (Msg 2 and Msg4) of the four-step RACH procedure. For example, MsgB 230 may include an index of the preamble 227, a UE identifier, a timing advance, a back-off indicator, a contention resolution message, power control parameters, and the like. Additionally, the two-step RACH procedures may be applied for UEs in the RRC connected, RRC idle, and RRC inactive states.

In some cases, wireless communications system 200 may support the allocation of resources for multiple RACH procedures supported by the system, where RACH occasions (e.g., time/frequency resources) may be shared, for example, between two-step RACH procedures and four-step RACH procedures. Additionally, some UEs 115 may be capable of performing two-step RACH procedures, four-step RACH procedures, or both. However, as a result of the shared resources between different types of RACH procedures, scrambling sequence configurations may be desired to allow a UE to encode a data payload of MsgA 225 of the two-step RACH procedure, while also enabling base station 105-a to decode the uplink data payload. Configurations for identifiers and scrambling sequences for MsgB 230 may likewise provide for efficiency in the system when RACH occasions are shared. Further, techniques that prevent ambiguity in downlink control channel reception at the UE 115 may also be desired.

As an example, data scrambling may be used to provide inter-cell interference randomization when different scrambling sequences are used among neighboring cells. As mentioned above, in four-step RACH procedures, the scrambling of a PUSCH payload (sent via the third message 215) may be based on the TC-RNTI provided by base station 105-a in the second message 210. In two-step RACH procedures, however, there may not be a configured RNTI (e.g., configured via higher-layers) available for UE 115-b to scramble a payload of MsgA 225, particularly in cases where UE 115-b is in an RRC idle or RRC inactive state. Moreover, if UE 115-b were to autonomously determine a data scrambling sequence for MsgA 225, the sequence selected by UE 115-b may not be known to base station 105-a, thereby preventing base station 105-a from decoding the contents of MsgA 225 when received. As described herein, various techniques may be used to specify scrambling sequences for MsgA 225 transmissions. In some aspects, the described techniques may also assist in avoiding collisions by reducing the likelihood of multiple UEs 115 using the same scrambling sequence when transmitting MsgA 225.

In some aspects, the data scrambling of MsgA 225 for a two-step RACH procedure may be associated at least with a preamble index used by UE 115-b. For example, a set of identifiers for MsgA 225 (e.g., a set of MsgA-RNTIs) may be configured by a network. The set of MsgA-RNTIs and an association with preamble indexes may then be broadcasted from base station 105-a to one or more UEs 115. In such cases, each MsgA-RNTI of the set of MsgA-RNTIs may be associated with a respective preamble index, and the association may be indicated to a set of UEs 115 within the cell via a broadcast message (e.g., the indication may be sent using system information, such as remaining minimum system information (RMSI) ) . The scrambling sequence for the payload of the PUSCH 229 included in MsgA 225 may then be determined based on the MsgA-RNTI selected by UE 115-b as well as the associated time/frequency resource index for the transmission of preamble 227 (e.g., associated with the RA-RNTI or the RACH occasion) . That is, the scrambling sequence may be determined based on information associated with a cell (e.g., the configured MsgA-RNTI) and the identifier associated with the resources used to transmit the preamble 227 of MsgA 225 (e.g., the RA-RNTI) . In such cases, the use of the broadcast signaling providing the MsgA-RNTIs may ensure that both UE 115-b and base station 105-a are able to efficiently determine the scrambling sequence for the uplink data payload of MsgA 225.

Additionally or alternatively, techniques may be used that reduce signaling overhead while allowing for both UE 115-b and base station 105-a to know the scrambling sequence used for MsgA 225 transmissions. For example, base station 105-a may refrain from broadcasting the information regarding the association between a configured set of MsgA-RNTIs and preamble indexes, and the scrambling sequence for the PUSCH 229 sent via MsgA 225 may be determined based on an index of the preamble 227 selected by UE 115-b, cell-specific parameters (e.g., a physical cell identifier) , as well as the associated time/frequency resources used to transmit the preamble 227. Here, the scrambling sequence may again be generated based on the information associated with the cell (e.g., the cell-specific parameters) and the identifier associated with resources used for transmitting MsgA 225 (e.g., the resources for transmitting the preamble of MsgA 225) . In some cases, an association between the scrambling sequence, preamble indexes, cell-specific parameter (s) , and time/frequency resources for preamble 227 transmissions may be configured by the network, and may also be indicated by base station 105-a to one or more UEs 115. As an example, the association may be indicated using information included in a broadcast message (e.g., sent via RMSI or other system information) . Alternatively, the configuration of the association between the scrambling sequence, preamble indexes, the cell-specific parameter (s) , and the associated time/frequency resources for preamble 227 transmissions may be preconfigured (e.g., in wireless communications standards) .

The techniques described herein further address the identifier and scrambling sequences used for MsgB 230 transmissions when RACH occasions are shared between different types of RACH procedures. For instance, in four-step RACH procedures, a PDCCH in Msg2 may be addressed to an RA-RNTI that identifies the time/frequency resources on which the preamble 227 was transmitted/detected. The RA-RNTI may also be used to generate the scrambling sequence for a downlink data payload of Msg2. If the same approach is used for MsgB 230 of the two-step RACH procedure (e.g., using a similar RA-RNTI for MsgB 230 transmissions) , multiple UEs 115 that collide when selecting the same RACH occasion may receive the same MsgB 230, which may complicate contention resolution. However, in some cases, MsgB 230 may be transmitted in a unicast manner to a particular UE 115 (e.g., for security reasons because a UE identifier is included in the payload of MsgB 230) .

As described herein, RNTI and data scrambling sequences for MsgB 230 of the two-step RACH procedure may be based on an identifier associated with the resources for MsgA or an identifier of UE 115-b. Specifically, an identifier associated with MsgB 230 (e.g., a MsgB-RNTI) may be used by base station 105-a for MsgB 230 transmissions, where the MsgB-RNTI may be associated with a RACH occasion corresponding to MsgA 225. As an example, the MsgB-RNTI may be determined based on an identifier associated with time/frequency resources of the RACH occasion for the transmission of MsgA 225. In such cases, the PDCCH 232 used for scheduling the PDSCH 234 of MsgB 230 may be addressed to, for example, an RA-RNTI corresponding to the preamble 227 included in MsgA 225 (e.g., the cyclic redundancy check (CRC) of the PDCCH 232 may be scrambled using the RA-RNTI) . Further, the MsgB-RNTI may be used to generate the data scrambling sequence for the downlink data payload of the PDSCH 234 scheduled by the PDCCH 232 of MsgB 230.

In some cases, the payload of the PDSCH 234 within MsgB 230 may include contention resolution information. For instance, contention resolution information may be included in a MAC control element (MAC-CE) and/or may be included in a MAC header of a MAC protocol data unit (PDU) in the PDSCH 234. MsgB 230 may also include an uplink grant to multiple UEs 115 associated with the same RACH occasion. Additionally, DCI sent via MsgB 230 may include contention resolution information. In any case, the information transmitted in MsgB 230 (either included in the PDSCH 234 or the PDCCH 232) may include information used by a particular UE 115 to determine that the downlink data payload is intended for that UE 115.

In other examples, the MsgB-RNTI may be determined based on a UE identifier included in MsgA 225. As an example, the UE identifier may include at least a portion of a UE identity (UE ID) , such as first set of bits of the UE ID, a last set of bits of the UE ID, or the like. In such cases, the full UE ID may not be used for determining the MsgB-RNTI and part of the UE ID may suffice. Additionally or alternatively, the UE identifier may include the identifier associated with the transmission of MsgA 225 (e.g., a MsgA-RNTI) . In such cases, the MsgB-RNTI may be determined based on a combination of the time/frequency resources of the RACH occasion, an index of the preamble 227, a physical cell identity, and the like) . Data scrambling for a downlink data payload of the PDSCH 234 transmitted using MsgB 230 may be based on the MsgB-RNTI and the preamble index associated with MsgB 230. As a result, the MsgB-RNTI may enable a dedicated MsgB 230 to be transmitted for each received preamble 227 and/or UE 115. Further the UE identifier used for the generation of the MsgB-RNTI may provide for conflict resolution for UEs 115 receiving a same MsgB 230.

As indicated above, there may be some ambiguity in the reception of PDCCH when two-step RACH procedures and four-step RACH procedures share RACH occasions. As an example, in four-step RACH procedures, a PDCCH that scheduled the PDSCH including the payload of Msg2 may be received within a RAR window following the transmission of Msg1. For instance, the RAR window may begin at least one symbol period (e.g., OFDM symbol period) after the RACH occasion, and the length of the window may correspond to a quantity of slots (but may be less than or equal to 10 ms) . However, ambiguity may exist for respective UEs 115 performing two-step RACH procedures and four-step RACH procedures, where there may be an unclear interpretation of a received PDCCH with shared RACH occasions. For instance, UE 115-b, performing a two-step RACH procedure, may detect a PDCCH for a four-step RACH procedure, and may inadvertently determine a RACH failure when UE 115-b is unable to identify its UE identifier in the corresponding PDSCH. As a result, various techniques may be used to reduce or eliminate this ambiguity in PDCCH reception.

In some cases, to resolve the ambiguity of PDCCHs corresponding to respective RACH procedures, a network may configure different resources for different types of RACH procedures that share RACH occasions. In a first example, different CORESETs and/or search spaces may be configured for different types of RACH procedures. As such, a first CORESET/search space may be configured for two-step RACH procedures and a second CORESET/search space may be configured for four-step RACH procedures. The configuration may be indicated by base station 105-a or may be predefined. Here, the same equation may be used to identify the respective identifier for different types of RACH procedures (e.g., RA-RNTI for four-step RACH procedures and the MsgB-RNTI for two-step RACH procedures) . Accordingly, the different CORESETs/search spaces may enable a UE 115 to determine a PDCCH (and, by extension, the PDSCH) associated with the transmission of a preamble 227 (e.g., a preamble sequence) from the UE 115 by monitoring the respected CORESET/search space associated with the type of RACH procedure initiated.

In a second example, base station 105-a may configure a same CORESET/search space for both two-step RACH and four-step RACH procedures, but using different, non-overlapping, RAR windows for two-step RACH and four-step RACH procedures. For instance, a first RAR window for a two-step RACH procedure may be configured to be before or after a second RAR window for four-step RACH procedures, where the first RAR window and the second RAR window do not overlap (e.g., in time) . Identical equations may again be used to identify the RA-RNTI for the four-step RACH procedure and the MsgB-RNTI for the two-step RACH procedure. In such cases, by monitoring for PDCCH during a respective RAR window that corresponds to the type of RACH procedure used, a UE 115 may efficiently identify the correct PDCCH and PDSCH for the type of RACH procedure the UE 115 initiated.

In a third example, the PDCCH ambiguity may be avoided through the configuration of an offset in an identifier associated with the resources used for transmitting a first message of a RACH procedure. For example, a MsgB-RNTI for a two-step RACH procedure may include an offset that is used to distinguish PDCCH (and PDSCH) received for two-step RACH procedures from PDCCH (and PDSCH) received for four-step RACH procedures. In some cases, the offset added to the MsgB-RNTI may be a fixed offset such that the UE 115 and base station 105-a both know the value of the offset (where the RA-RNTI for the four-step RACH procedure may not include an offset) . When using the offset included with the MsgB-RNTI to distinguish between signals sent for two-step and four-step RACH procedures, base station 105-a may also configure a same CORESET/search space for both the two-step and the four-step RACH procedures. Additionally or alternatively, the two-step RACH procedure and the four-step RACH procedure may be configured with RAR windows that at least partially overlap. For instance, a first RAR window for two-step RACH procedures may overlap in time (e.g., partially or fully) with a second RAR window used for four-step RACH procedures. As a result, a UE 115 may refrain from monitoring different resources for the PDCCH transmitted by base station 105-a, but may still efficiently distinguish PDCCH and PDSCH associated with different types of RACH procedures based on the offset added to the identifier associated with the resources for the RACH occasion.

Through the described techniques, UE 115-b may select a scrambling sequence known to the network for use when transmitting MsgA 225 such that base station 105-a is able to decode the payload of MsgA 225 when RACH occasions are shared between two-step and other types of RACH procedures. Further, the techniques for selecting a MsgB-RNTI may enhance conflict resolution when multiple UEs 115 transmit at the same RACH occasion. The various schemes for configuring different resources and offsets for different types of RACH procedures may enable UE 115-b to efficiently identify downlink transmissions associated with a particular RACH procedure the UE 115 initiated.

FIG. 3 illustrates an example of a process flow 300 in a system that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. In some examples, process flow 300 may implement aspects of wireless communications system 100. For example, process flow 300 may include a UE 115-c and a base station 105-b, which may be examples of the corresponding devices described with reference to FIG. 1. Process flow 300 may illustrate the use of an RNTI and scrambling design that supports the shared RACH occasions between two-step RACH procedures and four-step RACH procedures.

In some examples, at 305, base station 105-b may configure a set of message identifiers for a cell, where the message identifier may include a set of MsgA-RNTIs for a first message of the two-step RACH procedure. In some cases, base station 105-b may also configure an association for each MsgA-RNTI and a respective preamble index. Additionally or alternatively, base station 105-b may configure an association between a scrambling sequence to be used for MsgA transmission, the preamble indexes, cell-specific parameter (s) , and associated time/frequency resource for preamble transmissions.

At 310, base station may optionally transmit an indication of the configured MsgA-RNTIs and the associations. In some cases, the transmission may include a broadcast message, and the indication of the configured associations may be included in system information of the broadcast message.

At 315, UE 115-c may identify resources of the cell for transmitting the first message (e.g., MsgA) of the two-step RACH procedure. As an example, a RACH configuration of the cell may correspond to a particular set of time/frequency resources that may be used for transmitting a preamble sequence for two-step RACH procedures.

At 320 UE 115-c may also identify information associated with the cell, which may include identifying the configured association between each of the set of MsgA-RNTIs and a respective preamble sequence index. Additionally or alternatively, UE 115-c may identify cell-specific parameters such as a physical cell identity. UE 115-c may also identify the configured association between scrambling sequences, preamble indexes, cell-specific parameters, and the identified resources though the message transmitted by base station 105-b at 310. Alternatively the association information may be predetermined and UE 115-c may determine the association without receiving signaling from base station 105-b.

At 325 UE 115-c may determine a scrambling sequence based on the information associated with the cell and an identifier associated with the identified resources (e.g., an RA-RNTI) . More specifically, the identifier is associated with resources used for the transmission of a preamble sequence in MsgA of the two-step RACH procedure. In some cases, UE 115-c may determine the scrambling sequence based on a combination of the information associated with the cell (e.g., a selected preamble index and cell-specific parameters) and the RA-RNTI.

At 330 UE 115-c may scramble a data payload of MsgA, and at 335, UE 115-c may transmit, and base station 105-b may receive MsgA of the two-step RACH procedure. MsgA may accordingly include the selected preamble sequence and the scrambled data payload.

At 340 base station 105-b may also identify the resources MsgA was transmitted on, which may be indicative of an RA-RNTI, and at 345, may determine a descrambling sequence based on the information associated with the cell and the RA-RNTI. Thus, once base station 105-b receives the preamble of MsgA, then the base station may determine what the scrambling sequence may be for an associated PUSCH sent in MsgA. Accordingly, base station 105-b may descramble the data payload received via MsgA.

At 355 base station 105-b may transmit MsgB to UE 115-c based on identifying the information included within MsgA.

FIG. 4 illustrates an example of a process flow 400 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. In some examples, process flow 400 may implement aspects of wireless communications system 100. Process flow 400 may include a UE 115-d and base station 105-c, which may be examples of the corresponding devices described with reference to FIG. 1. Process flow 400 may illustrate the use of an RNTI and scrambling design that supports the shared RACH occasions between two-step RACH procedures and four-step RACH procedures.

At 405, UE 115-d may transmit, and base station 105-c may receive a first message (e.g., MsgA) of the two-step RACH procedure. As described herein, MsgA may include a preamble sequence and an uplink data payload (e.g., carried via PUSCH) . In some cases, the uplink data payload may include an identifier associated with MsgA. For example, the identifier may include a UE identifier included in MsgA, which may include a part of a UE ID associated with UE 115-d (e.g., a last 16 bits of the UE ID) or the full UE ID associated with UE 115-d. In other examples, the identifier may include a MsgA-RNTI conveyed by MsgA (where the MsgA-RNTI may indicate a combination of time/frequency resources of the RACH occasion, a preamble index, a physical cell ID, etc. ) .

In some cases, base station 105-c may determine a MsgB-RNTI based on the time/frequency resources used for MsgA (e.g., corresponding to a RA-RNTI that is associated with the resources carrying the preamble sequence of MsgA) . Additionally or alternatively, the MsgB-RNTI may be determined based on the identifier associated with the first message (e.g., the MsgA-RNTI or the partial UE ID) . At 410, base station 105-c may encode control information using the determined MsgB-RNTI, where the control information may be included in a PDCCH of the MsgB transmission.

At 415, base station 105-c may also generate a data scrambling sequence for the PDSCH included in MsgB, where the determined MsgB-RNTI is used to generate the scrambling sequence. Additionally or alternatively, the MsgA-RNTI conveyed by the received MsgA may be used by base station 105-c to generate the scrambling sequence. As a result, the MsgB-RNTI may be associated at least with a RACH occasion corresponding to the MsgA transmission. In any case, at 420, base station 105-c may scramble the downlink data payload using the determined scrambling sequence.

Base station 105-c may then, at 425, transmit MsgB of the two-step RACH procedure. MsgB may include the scrambled downlink data payload and the control channel including the encoded control information. At 430, UE 115-d may decode the control information from the PDCCH of MsgB based on the identifier associated with MsgA (e.g., the UE ID, the MsgA-RNTI, an RA-RNTI) . In other cases, the MsgB-RNTI may be used to decode the control information. Further, at 435, UE 115-d may determine a descrambling sequence for the downlink data payload based on the identifier associated with MsgA.

As such, at 440, UE 115-d may descramble the downlink data payload using the descrambling sequence. At 445, may also identify that the downlink data payload is associated with UE 115-d based on the identifier associated with the first message. Additionally or alternatively, UE 115-d may identify that the downlink data payload is associated with UE 115-d based at least in part on information included in the downlink data payload. In some examples, identifying that the downlink data payload is associated with UE 115-d may be based on receiving MAC CE (e.g., including a UE-specific identifier) , a MAC header, or the DCI.

FIG. 5 illustrates an example of a process flow 500 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. In some examples, process flow 500 may implement aspects of wireless communications system 100. Process flow 500 may include a UE 115-e and base station 105-d, which may be examples of the corresponding devices described with reference to FIG. 1. Process flow 500 may illustrate techniques used for the resolution of PDCCH ambiguity when multiple RACH procedures share a same RACH occasion.

At 505, base station 105-d may identify a configuration including a first set of resources associated with a two-step RACH procedure and a second set of resources associated with a four-step RACH procedure. In some cases, the first set of resources includes a first CORESET and/or first search space and the second set of resources comprises a second CORESET and/or second search space. In some cases, the first set of resources includes a first RAR window and the second set of resources comprises a second RAR window that is non-overlapping with the first RAR window.

Additionally or alternatively, the first set of resources and the second set of resources include a same CORESET and/or search space for the two-step RACH procedure and the four-step RACH procedure. In addition, the first set of resources includes a first RAR window and the second set of resources includes a second RAR window that is at least partially overlapping with the first RAR window. In such cases, base station 105-d may also identify an offset for an identifier associated with random access resources (e.g., resources corresponding to a transmission of MsgB of a two-step RACH procedure) .

At 510, base station 105-d may optionally transmit a message to UE 115-e indicating the configuration of the resources for the two-step RACH procedure and the four-step RACH procedure. In such cases, UE 115-e may identify the configuration based on the received message. In other cases, the configuration may be predefined, and UE 115-e may identify the configuration without receiving signaling from base station 105-d.

At 515, UE 115-e may initiate a RACH procedure (e.g., a two-step RACH procedure or a four-step RACH procedure) by sending a first message that includes a preamble sequence. The first message may be transmitted over a random access resource. Based on the received message, base station 105-d may determine an identifier associated with the random access resources (e.g., an RA-RNTI or a MsgB-RNTI) for downlink information to be included in a second message to UE 115-e. In such cases, identical equations may be used to identify RA-RNTI for 4-step RACH and MsgB-RNTI for 2-step RACH. In other cases, such as when the configured resources include a same CORESET/search space and overlapping RAR windows, the MsgB-RNTI may include the determined offset.

At 520, base station 105-d may encode control information based on the identifier associated with the random access resource (e.g., an RA-RNTI or a MsgB-RNTI) . Alternatively, the control information may be encoded based on the offset and the identifier associated with the random access resource. At 525, UE 115-e may monitor for a second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources.

At 530, base station 105-d may transmit the second message of the RACH procedure based on the configuration of the first set of resources and the second set of resources. The second message may include the encoded control information and a downlink data payload. At 535, UE 115-e may decode the control information of the second message based on the identifier (e.g., the RA-RNTI or MsgB-RNTI, based on the RACH procedure used) . At 540, UE 115-e may receive a downlink data payload of the second message based on the control information.

FIG. 6 shows a block diagram 600 of a device 605 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The device 605 may be an example of aspects of a UE 115 as described herein. The device 605 may include a receiver 610, a UE random access manager 615, and a transmitter 620. The device 605 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to radio network temporary identifier and scrambling for two-step random access channel procedures, etc. ) . Information may be passed on to other components of the device 605. The receiver 610 may be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 610 may utilize a single antenna or a set of antennas.

The UE random access manager 615 may identify time/frequency resources of a cell for transmitting a first message of a two-step random access channel procedure, identify information associated with the cell, determine a scrambling sequence based on the information associated with the cell and an identifier associated with the time/frequency resources, scramble a data payload of the first message using the determined scrambling sequence, and transmit the first message of the two-step random access channel procedure, the first message including a preamble sequence and the scrambled data payload.

The UE random access manager 615 may also transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure, receive, based on the control information, a downlink data payload of the second message, identify that the downlink data payload is associated with the UE based on information included in the downlink data payload, decode control information from the control channel based on an identifier associated with time/frequency resources of the first message, determine, based on the identifier associated with the time/frequency resources of the first message, a descrambling sequence for the downlink data payload, and descramble the downlink data payload using the descrambling sequence.

The UE random access manager 615 may also transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure, receive, based on the control information, a downlink data payload of the second message, identify that the downlink data payload is associated with the UE based on the identifier associated with the first message, decode control information from the control channel based on the identifier associated with the first message, determine, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload, and descramble the downlink data payload using the descrambling sequence.

The UE random access manager 615 may also transmit a first message of a random access channel procedure over a random access resource, monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, receive, based on the control information, a downlink data payload of the second message, identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure, and decode control information of the second message based on an identifier associated with the random access resource.

The UE random access manager 615 may also transmit a first message of a random access channel procedure over a random access resource, monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, receive, based on the control information, a downlink data payload of the second message, identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure, identify an offset for an identifier associated with the random access resource, and decode control information of the second message based on the identifier and the offset. The UE random access manager 615 may be an example of aspects of the UE random access manager 910 described herein.

The UE random access manager 615, or its sub-components, may be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the UE random access manager 615, or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC) , a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The UE random access manager 615, or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the UE random access manager 615, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the UE random access manager 615, or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

The transmitter 620 may transmit signals generated by other components of the device 605. In some examples, the transmitter 620 may be collocated with a receiver 610 in a transceiver module. For example, the transmitter 620 may be an example of aspects of the transceiver 920 described with reference to FIG. 9. The transmitter 620 may utilize a single antenna or a set of antennas.

FIG. 7 shows a block diagram 700 of a device 705 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The device 705 may be an example of aspects of a device 605, or a UE 115 as described herein. The device 705 may include a receiver 710, a UE random access manager 715, and a transmitter 750. The device 705 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 710 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to radio network temporary identifier and scrambling for two-step random access channel procedures, etc. ) . Information may be passed on to other components of the device 705. The receiver 710 may be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 710 may utilize a single antenna or a set of antennas.

The UE random access manager 715 may be an example of aspects of the UE random access manager 615 as described herein. The UE random access manager 715 may include a resource component 720, a cell information component 725, a scrambling manager 730, a UE communications manager 735, a decoder 740, and a configuration manager 745. The UE random access manager 715 may be an example of aspects of the UE random access manager 910 described herein.

The resource component 720 may identify resources of a cell for transmitting a first message of a two-step random access channel procedure. The cell information component 725 may identify information associated with the cell. The scrambling manager 730 may determine a scrambling sequence based on the information associated with the cell and an identifier associated with the resources and scramble a data payload of the first message using the determined scrambling sequence. The scrambling manager 730 may determine, based on the identifier associated with the resources of the first message, a descrambling sequence for the downlink data payload and descramble the downlink data payload using the descrambling sequence. The scrambling manager 730 may determine, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload and descramble the downlink data payload using the descrambling sequence.

The UE communications manager 735 may transmit the first message of the two-step random access channel procedure, the first message including a preamble sequence and the scrambled data payload. The UE communications manager 735 may transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure, receive, based on the control information, a downlink data payload of the second message, and identify that the downlink data payload is associated with the UE based on information included in the downlink data payload.

The UE communications manager 735 may transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure, receive, based on the control information, a downlink data payload of the second message, and identify that the downlink data payload is associated with the UE based on the identifier associated with the first message.

The UE communications manager 735 may transmit a first message of a random access channel procedure over a random access resource, monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, and receive, based on the control information, a downlink data payload of the second message. The UE communications manager 735 may transmit a first message of a random access channel procedure over a random access resource, monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, and receive, based on the control information, a downlink data payload of the second message.

The decoder 740 may decode control information from the control channel based on an identifier associated with resources of the first message. The decoder 740 may decode control information from the control channel based on the identifier associated with the first message. The decoder 740 may decode control information of the second message based on an identifier associated with the random access resource. The decoder 740 may decode control information of the second message based on the identifier and the offset.

The configuration manager 745 may identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure. The configuration manager 745 may identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure and identify an offset for an identifier associated with the random access resource.

The transmitter 750 may transmit signals generated by other components of the device 705. In some examples, the transmitter 750 may be collocated with a receiver 710 in a transceiver module. For example, the transmitter 750 may be an example of aspects of the transceiver 920 described with reference to FIG. 9. The transmitter 750 may utilize a single antenna or a set of antennas.

FIG. 8 shows a block diagram 800 of a UE random access manager 805 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The UE random access manager 805 may be an example of aspects of a UE random access manager 615, a UE random access manager 715, or a UE random access manager 910 described herein. The UE random access manager 805 may include a resource component 810, a cell information component 815, a scrambling manager 820, a UE communications manager 825, a decoder 830, and a configuration manager 835. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The resource component 810 may identify resources of a cell for transmitting a first message of a two-step random access channel procedure. The cell information component 815 may identify information associated with the cell. In some examples, identifying the information associated with the cell includes receiving a broadcast message indicating an association between each of a set of message identifiers and a respective preamble sequence index. In some examples, identifying the information associated with the cell includes receiving a cell identifier.

The scrambling manager 820 may determine a scrambling sequence based on the information associated with the cell and an identifier associated with the resources. In some examples, the scrambling manager 820 may scramble a data payload of the first message using the determined scrambling sequence. In some examples, the scrambling manager 820 may determine, based on the identifier associated with the resources of the first message, a descrambling sequence for the downlink data payload.

In some examples, the scrambling manager 820 may descramble the downlink data payload using the descrambling sequence. In some examples, the scrambling manager 820 may determine, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload. In some examples, the scrambling manager 820 may descramble the downlink data payload using the descrambling sequence.

In some examples, the scrambling manager 820 may determine the scrambling sequence is based on resources for transmitting the preamble sequence. In some examples, the scrambling manager 820 may determine the scrambling sequence based on a message identifier of the set of message identifiers associated with the preamble sequence.

In some examples, the scrambling manager 820 may determine an association between the scrambling sequence and one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence. In some cases, the broadcast message includes a system information message broadcast by the cell.

The UE communications manager 825 may transmit the first message of the two-step random access channel procedure, the first message including a preamble sequence and the scrambled data payload. In some examples, the UE communications manager 825 may transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload. In some examples, the UE communications manager 825 may receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure.

In some examples, the UE communications manager 825 may receive, based on the control information, a downlink data payload of the second message. In some examples, the UE communications manager 825 may identify that the downlink data payload is associated with the UE based on information included in the downlink data payload. In some examples, the UE communications manager 825 may transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message.

In some examples, the UE communications manager 825 may receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure. In some examples, the UE communications manager 825 may receive, based on the control information, a downlink data payload of the second message. In some examples, the UE communications manager 825 may identify that the downlink data payload is associated with the UE based on the identifier associated with the first message.

In some examples, the UE communications manager 825 may transmit a first message of a random access channel procedure over a random access resource. In some examples, the UE communications manager 825 may monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources.

In some examples, the UE communications manager 825 may receive, based on the control information, a downlink data payload of the second message. In some examples, the UE communications manager 825 may transmit a first message of a random access channel procedure over a random access resource. In some examples, the UE communications manager 825 may monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources.

In some examples, the UE communications manager 825 may receive, based on the control information, a downlink data payload of the second message. In some examples, the UE communications manager 825 may receive a broadcast message indicating a configuration of the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence. In some examples, the UE communications manager 825 may identify that the downlink data payload is associated with the UE is based on at least one of a MAC CE, a MAC header, or the control information.

In some cases, a configuration of the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence is predetermined.

In some cases, the identifier associated with the first message includes at least a portion of an identifier of the UE. In some cases, the identifier associated with the first message includes a scrambling sequence used to scramble the uplink data payload. In some cases, the identifier associated with the first message is based on time/frequency resources for transmitting the first message, an index of the preamble sequence, and a cell identifier.

The decoder 830 may decode control information from the control channel based on an identifier associated with resources of the first message. In some examples, the decoder 830 may decode control information from the control channel based on the identifier associated with the first message. In some examples, the decoder 830 may decode control information of the second message based on an identifier associated with the random access resource.

In some examples, the decoder 830 may decode control information of the second message based on the identifier and the offset. The configuration manager 835 may identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure.

In some examples, the configuration manager 835 may identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure. In some examples, the configuration manager 835 may identify an offset for an identifier associated with the random access resource.

In some examples, the configuration manager 835 may receive a message indicating the configuration. In some examples, the configuration manager 835 may receive a message indicating the configuration. In some cases, the first set of resources includes a first control resource set and the second set of resources includes a second control resource set.

In some cases, the first set of resources includes a first random access response window and the second set of resources includes a second random access response window that is non-overlapping with the first random access response window. In some cases, the configuration is predetermined. In some cases, the offset includes a first offset associated with the two-step random access channel procedure or a second offset associated with the four-step random access channel procedure.

In some cases, the first set of resources includes a control resource set and a first random access response window, and the second set of resources includes the control resource set and a second random access response window that is at least partially overlapping with the first random access response window. In some cases, the configuration is predetermined.

FIG. 9 shows a diagram of a system 900 including a device 905 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The device 905 may be an example of or include the components of device 605, device 705, or a UE 115 as described herein. The device 905 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a UE random access manager 910, an I/O controller 915, a transceiver 920, an antenna 925, memory 930, and a processor 940. These components may be in electronic communication via one or more buses (e.g., bus 945) .

The UE random access manager 910 may identify resources of a cell for transmitting a first message of a two-step random access channel procedure, identify information associated with the cell, determine a scrambling sequence based on the information associated with the cell and an identifier associated with the resources, scramble a data payload of the first message using the determined scrambling sequence, and transmit the first message of the two-step random access channel procedure, the first message including a preamble sequence and the scrambled data payload.

The UE random access manager 910 may also transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure, receive, based on the control information, a downlink data payload of the second message, identify that the downlink data payload is associated with the UE based on information included in the downlink data payload, decode control information from the control channel based on an identifier associated with resources of the first message, determine, based on the identifier associated with the resources of the first message, a descrambling sequence for the downlink data payload, and descramble the downlink data payload using the descrambling sequence.

The UE random access manager 910 may also transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure, receive, based on the control information, a downlink data payload of the second message, identify that the downlink data payload is associated with the UE based on the identifier associated with the first message, decode control information from the control channel based on the identifier associated with the first message, determine, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload, and descramble the downlink data payload using the descrambling sequence.

The UE random access manager 910 may also transmit a first message of a random access channel procedure over a random access resource, monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, receive, based on the control information, a downlink data payload of the second message, identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure, and decode control information of the second message based on an identifier associated with the random access resource.

The UE random access manager 910 may also transmit a first message of a random access channel procedure over a random access resource, monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, receive, based on the control information, a downlink data payload of the second message, identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure, identify an offset for an identifier associated with the random access resource, and decode control information of the second message based on the identifier and the offset.

The I/O controller 915 may manage input and output signals for the device 905. The I/O controller 915 may also manage peripherals not integrated into the device 905. In some cases, the I/O controller 915 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 915 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 915 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 915 may be implemented as part of a processor. In some cases, a user may interact with the device 905 via the I/O controller 915 or via hardware components controlled by the I/O controller 915.

The transceiver 920 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 920 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 920 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

In some cases, the wireless device may include a single antenna 925. However, in some cases the device may have more than one antenna 925, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 930 may include RAM and ROM. The memory 930 may store computer-readable, computer-executable code 935 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 930 may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 940 may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, the processor 940 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor 940. The processor 940 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks supporting radio network temporary identifier and scrambling for two-step random access channel procedures) .

The code 935 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code 935 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 935 may not be directly executable by the processor 940 but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

FIG. 10 shows a block diagram 1000 of a device 1005 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The device 1005 may be an example of aspects of a base station 105 as described herein. The device 1005 may include a receiver 1010, a base station random access manager 1015, and a transmitter 1020. The device 1005 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 1010 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to radio network temporary identifier and scrambling for two-step random access channel procedures, etc. ) . Information may be passed on to other components of the device 1005. The receiver 1010 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The receiver 1010 may utilize a single antenna or a set of antennas.

The base station random access manager 1015 may receive a first message of a two-step random access channel procedure in a cell, the first message including a preamble sequence and a scrambled data payload, identify time/frequency resources of the first message, determine a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the time/frequency resources, and descramble the scrambled data payload using the descrambling sequence.

The base station random access manager 1015 may also receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, transmit, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information, encode, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure, generate, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message, and scramble the downlink data payload using the scrambling sequence.

The base station random access manager 1015 may also receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, transmit, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information, encode, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure, generate, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message, and scramble the downlink data payload using the scrambling sequence.

The base station random access manager 1015 may also identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure, receive a first message of a random access channel procedure over a random access resource, transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload, and encode control information based on an identifier associated with the random access resource.

The base station random access manager 1015 may also identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure, determine an offset for the identifier associated with the random access resource, receive a first message of a random access channel procedure over a random access resource, transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload, and encode control information based on the offset and the identifier associated with the random access resource. The base station random access manager 1015 may be an example of aspects of the base station random access manager 1310 described herein.

The base station random access manager 1015, or its sub-components, may be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the base station random access manager 1015, or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC) , a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The base station random access manager 1015, or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the base station random access manager 1015, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the base station random access manager 1015, or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

The transmitter 1020 may transmit signals generated by other components of the device 1005. In some examples, the transmitter 1020 may be collocated with a receiver 1010 in a transceiver module. For example, the transmitter 1020 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The transmitter 1020 may utilize a single antenna or a set of antennas.

FIG. 11 shows a block diagram 1100 of a device 1105 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The device 1105 may be an example of aspects of a device 1005, or a base station 105 as described herein. The device 1105 may include a receiver 1110, a base station random access manager 1115, and a transmitter 1145. The device 1105 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 1110 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to radio network temporary identifier and scrambling for two-step random access channel procedures, etc. ) . Information may be passed on to other components of the device 1105. The receiver 1110 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The receiver 1110 may utilize a single antenna or a set of antennas.

The base station random access manager 1115 may be an example of aspects of the base station random access manager 1015 as described herein. The base station random access manager 1115 may include a base station communications manager 1120, a resource manager 1125, a base station scrambling manager 1130, an encoder 1135, and a configuration component 1140. The base station random access manager 1115 may be an example of aspects of the base station random access manager 1310 described herein.

The base station communications manager 1120 may receive a first message of a two-step random access channel procedure in a cell, the first message including a preamble sequence and a scrambled data payload. The resource manager 1125 may identify resources of the first message.

The base station scrambling manager 1130 may determine a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources and descramble the scrambled data payload using the descrambling sequence.

The base station communications manager 1120 may receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload and transmit, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

The encoder 1135 may encode, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure. The base station scrambling manager 1130 may generate, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message and scramble the downlink data payload using the scrambling sequence.

The base station communications manager 1120 may receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message and transmit, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information.

The encoder 1135 may encode, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure. The base station scrambling manager 1130 may generate, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message and scramble the downlink data payload using the scrambling sequence.

The configuration component 1140 may identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure. The base station communications manager 1120 may receive a first message of a random access channel procedure over a random access resource and transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

The encoder 1135 may encode control information based on an identifier associated with the random access resource. The configuration component 1140 may identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure and determine an offset for the identifier associated with the random access resource.

The base station communications manager 1120 may receive a first message of a random access channel procedure over a random access resource and transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload. The encoder 1135 may encode control information based on the offset and the identifier associated with the random access resource.

The transmitter 1145 may transmit signals generated by other components of the device 1105. In some examples, the transmitter 1145 may be collocated with a receiver 1110 in a transceiver module. For example, the transmitter 1145 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The transmitter 1145 may utilize a single antenna or a set of antennas.

FIG. 12 shows a block diagram 1200 of a base station random access manager 1205 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The base station random access manager 1205 may be an example of aspects of a base station random access manager 1015, a base station random access manager 1115, or a base station random access manager 1310 described herein. The base station random access manager 1205 may include a base station communications manager 1210, a resource manager 1215, a base station scrambling manager 1220, a configuration component 1225, and an encoder 1230. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The base station communications manager 1210 may receive a first message of a two-step random access channel procedure in a cell, the first message including a preamble sequence and a scrambled data payload. In some examples, the base station communications manager 1210 may receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload.

In some examples, the base station communications manager 1210 may transmit, to one or more UEs 115, the second message including the scrambled downlink data payload and the control channel including the encoded control information. In some examples, the base station communications manager 1210 may receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message.

In some examples, the base station communications manager 1210 may transmit, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information. In some examples, the base station communications manager 1210 may receive a first message of a random access channel procedure over a random access resource. In some examples, the base station communications manager 1210 may transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

In some examples, the base station communications manager 1210 may receive a first message of a random access channel procedure over a random access resource. In some examples, the base station communications manager 1210 may transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload.

In some examples, the base station communications manager 1210 may transmit a broadcast message indicating an association between each of the set of message identifiers and a respective preamble sequence index. In some examples, the base station communications manager 1210 may transmit a message indicating the configuration of the one or more cell-specific parameters.

In some examples, the base station communications manager 1210 may transmit a broadcast message indicating the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence. In some examples, the base station communications manager 1210 may determine that the downlink data payload is associated with a UE of the one or more UEs.

In some examples, the base station communications manager 1210 may transmit information within the downlink data payload that indicates the downlink data payload is associated with the UE. In some examples, the base station communications manager 1210 may transmit, to one or more UEs 115, a message indicating the configuration. In some examples, the base station communications manager 1210 may transmit, to one or more UEs 115, a message indicating the configuration.

In some cases, the broadcast message includes a system information message broadcast. In some cases, the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the one or more cell-specific parameters, and an index of the preamble sequence is predetermined. In some cases, the information within the downlink data payload includes a MAC control element indicating an identifier of the UE 115.

In some cases, the identifier associated with the first message includes an identifier of the UE. In some cases, the identifier associated with the first message includes a scrambling sequence used to scramble the uplink data payload. In some cases, the identifier associated with the first message is based on time/frequency resources for transmitting the first message, an index of the preamble sequence, and a cell identifier.

The resource manager 1215 may identify resources of the first message. The base station scrambling manager 1220 may determine a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources. In some examples, the base station scrambling manager 1220 may descramble the scrambled data payload using the descrambling sequence.

In some examples, the base station scrambling manager 1220 may generate, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message. In some examples, the base station scrambling manager 1220 may scramble the downlink data payload using the scrambling sequence.

In some examples, the base station scrambling manager 1220 may generate, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message. In some examples, the base station scrambling manager 1220 may scramble the downlink data payload using the scrambling sequence. In some examples, the base station scrambling manager 1220 may determine the descrambling sequence based on a message identifier of the set of message identifiers associated with the preamble sequence.

The configuration component 1225 may identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure. In some examples, the configuration component 1225 may identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure.

In some examples, the configuration component 1225 may determine an offset for the identifier associated with the random access resource. In some examples, the configuration component 1225 may configure a set of message identifiers for the cell. In some examples, the configuration component 1225 may determine a configuration of one or more cell-specific parameters.

In some examples, the configuration component 1225 may determine a configuration of an association between the scrambling sequence and one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence. In some cases, the first set of resources includes a first control resource set and the second set of resources includes a second control resource set.

In some cases, the first set of resources includes a first random access response window and the second set of resources includes a second random access response window that is non-overlapping with the first random access response window. In some cases, the offset includes a first offset associated with the two-step random access channel procedure or a second offset associated with the four-step random access channel procedure. In some cases, the first set of resources includes a control resource set and a first random access response window, and the second set of resources includes the control resource set and a second random access response window that is at least partially overlapping with the first random access response window.

The encoder 1230 may encode, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure. In some examples, the encoder 1230 may encode, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure.

In some examples, the encoder 1230 may encode control information based on an identifier associated with the random access resource. In some examples, the encoder 1230 may encode control information based on the offset and the identifier associated with the random access resource.

FIG. 13 shows a diagram of a system 1300 including a device 1305 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The device 1305 may be an example of or include the components of device 1005, device 1105, or a base station 105 as described herein. The device 1305 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a base station random access manager 1310, a network communications manager 1315, a transceiver 1320, an antenna 1325, memory 1330, a processor 1340, and an inter-station communications manager 1345. These components may be in electronic communication via one or more buses (e.g., bus 1350) .

The base station random access manager 1310 may receive a first message of a two-step random access channel procedure in a cell, the first message including a preamble sequence and a scrambled data payload, identify resources of the first message, determine a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources, and descramble the scrambled data payload using the descrambling sequence.

The base station random access manager 1310 may also receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, transmit, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information, encode, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure, generate, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message, and scramble the downlink data payload using the scrambling sequence.

The base station random access manager 1310 may also receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message, transmit, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information, encode, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure, generate, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message, and scramble the downlink data payload using the scrambling sequence.

The base station random access manager 1310 may also identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure, receive a first message of a random access channel procedure over a random access resource, transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload, and encode control information based on an identifier associated with the random access resource.

The base station random access manager 1310 may also identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure, determine an offset for the identifier associated with the random access resource, receive a first message of a random access channel procedure over a random access resource, transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload, and encode control information based on the offset and the identifier associated with the random access resource.

The network communications manager 1315 may manage communications with the core network (e.g., via one or more wired backhaul links) . For example, the network communications manager 1315 may manage the transfer of data communications for client devices, such as one or more UEs 115.

The transceiver 1320 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 1320 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1320 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

In some cases, the wireless device may include a single antenna 1325. However, in some cases the device may have more than one antenna 1325, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 1330 may include RAM, ROM, or a combination thereof. The memory 1330 may store computer-readable code 1335 including instructions that, when executed by a processor (e.g., the processor 1340) cause the device to perform various functions described herein. In some cases, the memory 1330 may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 1340 may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, the processor 1340 may be configured to operate a memory array using a memory controller. In some cases, a memory controller may be integrated into processor 1340. The processor 1340 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1330) to cause the device 1305 to perform various functions (e.g., functions or tasks supporting radio network temporary identifier and scrambling for two-step random access channel procedures) .

The inter-station communications manager 1345 may manage communications with other base station 105, and may include a controller or scheduler for controlling communications with UEs 115 in cooperation with other base stations 105. For example, the inter-station communications manager 1345 may coordinate scheduling for transmissions to UEs 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-station communications manager 1345 may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations 105.

The code 1335 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code 1335 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 1335 may not be directly executable by the processor 1340 but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

FIG. 14 shows a flowchart illustrating a method 1400 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 1400 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1400 may be performed by a UE random access manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1405, the UE may identify resources of a cell for transmitting a first message of a two-step random access channel procedure. The operations of 1405 may be performed according to the methods described herein. In some examples, aspects of the operations of 1405 may be performed by a resource component as described with reference to FIGs. 6 through 9.

At 1410, the UE may identify information associated with the cell. The operations of 1410 may be performed according to the methods described herein. In some examples, aspects of the operations of 1410 may be performed by a cell information component as described with reference to FIGs. 6 through 9.

At 1415, the UE may determine a scrambling sequence based on the information associated with the cell and an identifier associated with the resources. The operations of 1415 may be performed according to the methods described herein. In some examples, aspects of the operations of 1415 may be performed by a scrambling manager as described with reference to FIGs. 6 through 9.

At 1420, the UE may scramble a data payload of the first message using the determined scrambling sequence. The operations of 1420 may be performed according to the methods described herein. In some examples, aspects of the operations of 1420 may be performed by a scrambling manager as described with reference to FIGs. 6 through 9.

At 1425, the UE may transmit the first message of the two-step random access channel procedure, the first message including a preamble sequence and the scrambled data payload. The operations of 1425 may be performed according to the methods described herein. In some examples, aspects of the operations of 1425 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

FIG. 15 shows a flowchart illustrating a method 1500 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 1500 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1500 may be performed by a UE random access manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1505, the UE may transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload. The operations of 1505 may be performed according to the methods described herein. In some examples, aspects of the operations of 1505 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1510, the UE may receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure. The operations of 1510 may be performed according to the methods described herein. In some examples, aspects of the operations of 1510 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1515, the UE may decode control information from the control channel based on an identifier associated with resources of the first message. The operations of 1515 may be performed according to the methods described herein. In some examples, aspects of the operations of 1515 may be performed by a decoder as described with reference to FIGs. 6 through 9.

At 1520, the UE may receive, based on the control information, a downlink data payload of the second message. The operations of 1520 may be performed according to the methods described herein. In some examples, aspects of the operations of 1520 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1525, the UE may determine, based on the identifier associated with the resources of the first message, a descrambling sequence for the downlink data payload. The operations of 1525 may be performed according to the methods described herein. In some examples, aspects of the operations of 1525 may be performed by a scrambling manager as described with reference to FIGs. 6 through 9.

At 1530, the UE may descramble the downlink data payload using the descrambling sequence. The operations of 1530 may be performed according to the methods described herein. In some examples, aspects of the operations of 1530 may be performed by a scrambling manager as described with reference to FIGs. 6 through 9.

At 1535, the UE may identify that the downlink data payload is associated with the UE based on information included in the downlink data payload. The operations of 1535 may be performed according to the methods described herein. In some examples, aspects of the operations of 1535 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

FIG. 16 shows a flowchart illustrating a method 1600 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 1600 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1600 may be performed by a UE random access manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1605, the UE may transmit, to a base station, a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message. The operations of 1605 may be performed according to the methods described herein. In some examples, aspects of the operations of 1605 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1610, the UE may receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure. The operations of 1610 may be performed according to the methods described herein. In some examples, aspects of the operations of 1610 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1615, the UE may decode control information from the control channel based on the identifier associated with the first message. The operations of 1615 may be performed according to the methods described herein. In some examples, aspects of the operations of 1615 may be performed by a decoder as described with reference to FIGs. 6 through 9.

At 1620, the UE may receive, based on the control information, a downlink data payload of the second message. The operations of 1620 may be performed according to the methods described herein. In some examples, aspects of the operations of 1620 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1625, the UE may determine, based on the identifier associated with the first message, a descrambling sequence for the downlink data payload. The operations of 1625 may be performed according to the methods described herein. In some examples, aspects of the operations of 1625 may be performed by a scrambling manager as described with reference to FIGs. 6 through 9.

At 1630, the UE may descramble the downlink data payload using the descrambling sequence. The operations of 1630 may be performed according to the methods described herein. In some examples, aspects of the operations of 1630 may be performed by a scrambling manager as described with reference to FIGs. 6 through 9.

At 1635, the UE may identify that the downlink data payload is associated with the UE based on the identifier associated with the first message. The operations of 1635 may be performed according to the methods described herein. In some examples, aspects of the operations of 1635 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

FIG. 17 shows a flowchart illustrating a method 1700 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 1700 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1700 may be performed by a UE random access manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1705, the UE may transmit a first message of a random access channel procedure over a random access resource. The operations of 1705 may be performed according to the methods described herein. In some examples, aspects of the operations of 1705 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1710, the UE may identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure. The operations of 1710 may be performed according to the methods described herein. In some examples, aspects of the operations of 1710 may be performed by a configuration manager as described with reference to FIGs. 6 through 9.

At 1715, the UE may monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources. The operations of 1715 may be performed according to the methods described herein. In some examples, aspects of the operations of 1715 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1720, the UE may decode control information of the second message based on an identifier associated with the random access resource. The operations of 1720 may be performed according to the methods described herein. In some examples, aspects of the operations of 1720 may be performed by a decoder as described with reference to FIGs. 6 through 9.

At 1725, the UE may receive, based on the control information, a downlink data payload of the second message. The operations of 1725 may be performed according to the methods described herein. In some examples, aspects of the operations of 1725 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

FIG. 18 shows a flowchart illustrating a method 1800 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 1800 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1800 may be performed by a UE random access manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At 1805, the UE may transmit a first message of a random access channel procedure over a random access resource. The operations of 1805 may be performed according to the methods described herein. In some examples, aspects of the operations of 1805 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1810, the UE may identify a configuration including a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure. The operations of 1810 may be performed according to the methods described herein. In some examples, aspects of the operations of 1810 may be performed by a configuration manager as described with reference to FIGs. 6 through 9.

At 1815, the UE may monitor for a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources. The operations of 1815 may be performed according to the methods described herein. In some examples, aspects of the operations of 1815 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

At 1820, the UE may identify an offset for an identifier associated with the random access resource. The operations of 1820 may be performed according to the methods described herein. In some examples, aspects of the operations of 1820 may be performed by a configuration manager as described with reference to FIGs. 6 through 9.

At 1825, the UE may decode control information of the second message based on the identifier and the offset. The operations of 1825 may be performed according to the methods described herein. In some examples, aspects of the operations of 1825 may be performed by a decoder as described with reference to FIGs. 6 through 9.

At 1830, the UE may receive, based on the control information, a downlink data payload of the second message. The operations of 1830 may be performed according to the methods described herein. In some examples, aspects of the operations of 1830 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9.

FIG. 19 shows a flowchart illustrating a method 1900 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 1900 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 1900 may be performed by a base station random access manager as described with reference to FIGs. 10 through 13. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 1905, the base station may receive a first message of a two-step random access channel procedure in a cell, the first message including a preamble sequence and a scrambled data payload. The operations of 1905 may be performed according to the methods described herein. In some examples, aspects of the operations of 1905 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

At 1910, the base station may identify resources of the first message. The operations of 1910 may be performed according to the methods described herein. In some examples, aspects of the operations of 1910 may be performed by a resource manager as described with reference to FIGs. 10 through 13.

At 1915, the base station may determine a descrambling sequence used to descramble the scrambled data payload based on information associated with the cell and an identifier associated with the resources. The operations of 1915 may be performed according to the methods described herein. In some examples, aspects of the operations of 1915 may be performed by a base station scrambling manager as described with reference to FIGs. 10 through 13.

At 1920, the base station may descramble the scrambled data payload using the descrambling sequence. The operations of 1920 may be performed according to the methods described herein. In some examples, aspects of the operations of 1920 may be performed by a base station scrambling manager as described with reference to FIGs. 10 through 13.

FIG. 20 shows a flowchart illustrating a method 2000 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 2000 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 2000 may be performed by a base station random access manager as described with reference to FIGs. 10 through 13. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 2005, the base station may receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload. The operations of 2005 may be performed according to the methods described herein. In some examples, aspects of the operations of 2005 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

At 2010, the base station may encode, based on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure. The operations of 2010 may be performed according to the methods described herein. In some examples, aspects of the operations of 2010 may be performed by an encoder as described with reference to FIGs. 10 through 13.

At 2015, the base station may generate, based on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message. The operations of 2015 may be performed according to the methods described herein. In some examples, aspects of the operations of 2015 may be performed by a base station scrambling manager as described with reference to FIGs. 10 through 13.

At 2020, the base station may scramble the downlink data payload using the scrambling sequence. The operations of 2020 may be performed according to the methods described herein. In some examples, aspects of the operations of 2020 may be performed by a base station scrambling manager as described with reference to FIGs. 10 through 13.

At 2025, the base station may transmit, to one or more UEs, the second message including the scrambled downlink data payload and the control channel including the encoded control information. The operations of 2025 may be performed according to the methods described herein. In some examples, aspects of the operations of 2025 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

FIG. 21 shows a flowchart illustrating a method 2100 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 2100 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 2100 may be performed by a base station random access manager as described with reference to FIGs. 10 through 13. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 2105, the base station may receive a first message of a two-step random access channel procedure, the first message including a preamble sequence and an uplink data payload, the uplink data payload including an identifier associated with the first message. The operations of 2105 may be performed according to the methods described herein. In some examples, aspects of the operations of 2105 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

At 2110, the base station may encode, based on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure. The operations of 2110 may be performed according to the methods described herein. In some examples, aspects of the operations of 2110 may be performed by an encoder as described with reference to FIGs. 10 through 13.

At 2115, the base station may generate, based on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message. The operations of 2115 may be performed according to the methods described herein. In some examples, aspects of the operations of 2115 may be performed by a base station scrambling manager as described with reference to FIGs. 10 through 13.

At 2120, the base station may scramble the downlink data payload using the scrambling sequence. The operations of 2120 may be performed according to the methods described herein. In some examples, aspects of the operations of 2120 may be performed by a base station scrambling manager as described with reference to FIGs. 10 through 13.

At 2125, the base station may transmit, to a UE, the second message including the scrambled downlink data payload and the control channel including the encoded control information. The operations of 2125 may be performed according to the methods described herein. In some examples, aspects of the operations of 2125 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

FIG. 22 shows a flowchart illustrating a method 2200 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 2200 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 2200 may be performed by a base station random access manager as described with reference to FIGs. 10 through 13. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 2205, the base station may identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure. The operations of 2205 may be performed according to the methods described herein. In some examples, aspects of the operations of 2205 may be performed by a configuration component as described with reference to FIGs. 10 through 13.

At 2210, the base station may receive a first message of a random access channel procedure over a random access resource. The operations of 2210 may be performed according to the methods described herein. In some examples, aspects of the operations of 2210 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

At 2215, the base station may encode control information based on an identifier associated with the random access resource. The operations of 2215 may be performed according to the methods described herein. In some examples, aspects of the operations of 2215 may be performed by an encoder as described with reference to FIGs. 10 through 13.

At 2220, the base station may transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload. The operations of 2220 may be performed according to the methods described herein. In some examples, aspects of the operations of 2220 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

FIG. 23 shows a flowchart illustrating a method 2300 that supports radio network temporary identifier and scrambling for two-step random access channel procedures in accordance with aspects of the present disclosure. The operations of method 2300 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 2300 may be performed by a base station random access manager as described with reference to FIGs. 10 through 13. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, a base station may perform aspects of the functions described below using special-purpose hardware.

At 2305, the base station may identify a configuration including a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure. The operations of 2305 may be performed according to the methods described herein. In some examples, aspects of the operations of 2305 may be performed by a configuration component as described with reference to FIGs. 10 through 13.

At 2310, the base station may receive a first message of a random access channel procedure over a random access resource. The operations of 2310 may be performed according to the methods described herein. In some examples, aspects of the operations of 2310 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

At 2315, the base station may determine an offset for the identifier associated with the random access resource. The operations of 2315 may be performed according to the methods described herein. In some examples, aspects of the operations of 2315 may be performed by a configuration component as described with reference to FIGs. 10 through 13.

At 2320, the base station may encode control information based on the offset and the identifier associated with the random access resource. The operations of 2320 may be performed according to the methods described herein. In some examples, aspects of the operations of 2320 may be performed by an encoder as described with reference to FIGs. 10 through 13.

At 2325, the base station may transmit a second message of the random access channel procedure based on the configuration of the first set of resources and the second set of resources, the second message including the encoded control information and a downlink data payload. The operations of 2325 may be performed according to the methods described herein. In some examples, aspects of the operations of 2325 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13.

It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

Techniques described herein may be used for various wireless communications systems such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , single carrier frequency division multiple access (SC-FDMA) , and other systems. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA) , etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases may be commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD) , etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM) .

An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB) , Evolved UTRA (E-UTRA) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS) . LTE, LTE-A, and LTE-A Pro are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from the organization named “3rd Generation Partnership Project” (3GPP) . CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the systems and radio technologies mentioned herein as well as other systems and radio technologies. While aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR applications.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell may be associated with a lower-powered base station, as compared with a macro cell, and a small cell may operate in the same or different (e.g., licensed, unlicensed, etc. ) frequency bands as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG) , UEs for users in the home, and the like) . An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells, and may also support communications using one or multiple component carriers.

The wireless communications systems described herein may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include random-access memory (RAM) , read-only memory (ROM) , electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A method for wireless communications at a user equipment (UE) , comprising:

identifying time/frequency resources of a cell for transmitting a first message of a two-step random access channel procedure;

identifying information associated with the cell;

determining a scrambling sequence based at least in part on the information associated with the cell and an identifier associated with the time/frequency resources;

scrambling a data payload of the first message using the determined scrambling sequence; and

transmitting the first message of the two-step random access channel procedure, the first message comprising a preamble sequence and the scrambled data payload.
The method of claim 1, wherein:

identifying the information associated with the cell comprises receiving a broadcast message indicating an association between each of a set of message identifiers and a respective preamble sequence index; and

determining the scrambling sequence based at least in part on a message identifier of the set of message identifiers associated with the preamble sequence.
The method of claim 2, wherein the broadcast message comprises a system information message broadcast by the cell.
The method of claim 1, wherein:

identifying the information associated with the cell comprises receiving a cell identifier.
The method of claim 4, wherein determining the scrambling sequence comprises:

determining an association between the scrambling sequence and one or more of the identifier associated with the time/frequency resources for transmitting the first message, the cell identifier, and an index of the preamble sequence.
The method of claim 5, further comprising:

receiving a broadcast message indicating the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence.
The method of claim 5, wherein a configuration of the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence is predetermined.
A method for wireless communications at a user equipment (UE) , comprising:

transmitting, to a base station, a first message of a two-step random access channel procedure over a set of time/frequency resources, the first message comprising a preamble sequence and an uplink data payload;

receiving, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

decoding control information from the control channel based at least in part on an identifier associated with the set of time/frequency resources of the first message;

receiving, based at least in part on the control information, a downlink data payload of the second message;

determining, based at least in part on the identifier associated with the set of time/frequency resources of the first message, a descrambling sequence for the downlink data payload;

descrambling the downlink data payload using the descrambling sequence; and

identifying that the downlink data payload is associated with the UE based at least in part on information included in the downlink data payload.
The method of claim 8, wherein:

identifying that the downlink data payload is associated with the UE is based at least in part on at least one of a medium access control (MAC) control element, a MAC header, or the control information.
A method for wireless communications at a user equipment (UE) , comprising:

transmitting, to a base station, a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

receiving, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

decoding control information from the control channel based at least in part on the identifier associated with the first message;

receiving, based at least in part on the control information, a downlink data payload of the second message;

determining, based at least in part on the identifier associated with the first message, a descrambling sequence for the downlink data payload;

descrambling the downlink data payload using the descrambling sequence; and

identifying that the downlink data payload is associated with the UE based at least in part on the identifier associated with the first message.
The method of claim 10, wherein the identifier associated with the first message comprises at least a portion of an identifier of the UE.
The method of claim 10, wherein the identifier associated with the first message comprises a scrambling sequence used to scramble the uplink data payload.
The method of claim 12, wherein the identifier associated with the first message is based at least in part on time/frequency resources for transmitting the first message, an index of the preamble sequence, and a cell identifier.
A method for wireless communications at a user equipment (UE) , comprising:

transmitting a first message of a random access channel procedure over a random access resource;

identifying a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

monitoring for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

decoding control information of the second message based at least in part on an identifier associated with the random access resource; and

receiving, based at least in part on the control information, a downlink data payload of the second message.
The method of claim 14, wherein the first set of resources comprises a first control resource set and the second set of resources comprises a second control resource set.
The method of claim 14, wherein the first set of resources comprises a first random access response window and the second set of resources comprises a second random access response window that is non-overlapping with the first random access response window.
The method of claim 14, wherein identifying the configuration comprises:

receiving a message indicating the configuration.
The method of claim 14, wherein the configuration is predetermined.
A method for wireless communications at a user equipment (UE) , comprising:

transmitting a first message of a random access channel procedure over a random access resource;

identifying a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

monitoring for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

identifying an offset for an identifier associated with the random access resource;

decoding control information of the second message based at least in part on the identifier and the offset; and

receiving, based at least in part on the control information, a downlink data payload of the second message.
The method of claim 19, wherein the offset comprises a first offset associated with the two-step random access channel procedure or a second offset associated with the four-step random access channel procedure.
The method of claim 19, wherein the first set of resources comprises a control resource set and a first random access response window and the second set of resources comprises the control resource set and a second random access response window that is at least partially overlapping with the first random access response window.
The method of claim 19, wherein identifying the configuration comprises:

receiving a message indicating the configuration.
The method of claim 19, wherein the configuration is predetermined.
A method for wireless communications at a base station, comprising:

receiving a first message of a two-step random access channel procedure in a cell, the first message comprising a preamble sequence and a scrambled data payload;

identifying resources of the first message;

determining a descrambling sequence used to descramble the scrambled data payload based at least in part on information associated with the cell and an identifier associated with the resources; and

descrambling the scrambled data payload using the descrambling sequence.
The method of claim 24, further comprising:

configuring a set of message identifiers for the cell;

transmitting a broadcast message indicating an association between each of the set of message identifiers and a respective preamble sequence index; and

determining the descrambling sequence based at least in part on a message identifier of the set of message identifiers associated with the preamble sequence.
The method of claim 25, wherein the broadcast message comprises a system information message broadcast.
The method of claim 24, further comprising:

determining a configuration of one or more cell-specific parameters; and

transmitting a message indicating the configuration of the one or more cell-specific parameters.
The method of claim 27, further comprising:

determining a configuration of an association between the scrambling sequence and one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence.
The method of claim 28, further comprising:

transmitting a broadcast message indicating the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence.
The method of claim 28, wherein the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the one or more cell-specific parameters, and an index of the preamble sequence is predetermined.
A method for wireless communications at a base station, comprising:

receiving a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload;

encoding, based at least in part on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure;

generating, based at least in part on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message;

scrambling the downlink data payload using the scrambling sequence; and

transmitting, to one or more user equipment (UEs) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
The method of claim 31, further comprising:

determining that the downlink data payload is associated with a UE of the one or more UEs; and

transmitting information within the downlink data payload that indicates the downlink data payload is associated with the UE.
The method of claim 32, wherein the information within the downlink data payload comprises a medium access control (MAC) control element indicating an identifier of the UE.
A method for wireless communications at a base station, comprising:

receiving a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

encoding, based at least in part on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure;

generating, based at least in part on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message;

scrambling the downlink data payload using the scrambling sequence; and

transmitting, to a user equipment (UE) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
The method of claim 34, wherein the identifier associated with the first message comprises an identifier of the UE.
The method of claim 34, wherein the identifier associated with the first message comprises a scrambling sequence used to scramble the uplink data payload.
The method of claim 36, wherein the identifier associated with the first message is based at least in part on time/frequency resources for transmitting the first message, an index of the preamble sequence, and a cell identifier.
A method for wireless communications at a base station, comprising:

identifying a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

receiving a first message of a random access channel procedure over a random access resource;

encoding control information based at least in part on an identifier associated with the random access resource; and

transmitting a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.
The method of claim 38, wherein the first set of resources comprises a first control resource set and the second set of resources comprises a second control resource set.
The method of claim 38, wherein the first set of resources comprises a first random access response window and the second set of resources comprises a second random access response window that is non-overlapping with the first random access response window.
The method of claim 38, further comprising:

transmitting, to one or more user equipment (UEs) , a message indicating the configuration.
A method for wireless communications at a base station, comprising:

identifying a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

receiving a first message of a random access channel procedure over a random access resource;

determining an offset for the identifier associated with the random access resource;

encoding control information based at least in part on the offset and the identifier associated with the random access resource; and

transmitting a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.
The method of claim 42, wherein the offset comprises a first offset associated with the two-step random access channel procedure or a second offset associated with the four-step random access channel procedure.
The method of claim 42, wherein the first set of resources comprises a control resource set and a first random access response window and the second set of resources comprises the control resource set and a second random access response window that is at least partially overlapping with the first random access response window.
The method of claim 42, further comprising:

transmitting, to one or more user equipment (UEs) , a message indicating the configuration.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

identify resources of a cell for transmitting a first message of a two-step random access channel procedure;

identify information associated with the cell;

determine a scrambling sequence based at least in part on the information associated with the cell and an identifier associated with the resources;

scramble a data payload of the first message using the determined scrambling sequence; and

transmit the first message of the two-step random access channel procedure, the first message comprising a preamble sequence and the scrambled data payload.
The apparatus of claim 46, wherein:

the instructions to identify the information associated with the cell are executable by the processor to cause the apparatus to receive a broadcast message indicating an association between each of a set of message identifiers and a respective preamble sequence index; and

determine the scrambling sequence based at least in part on a message identifier of the set of message identifiers associated with the preamble sequence.
The apparatus of claim 47, wherein the broadcast message comprises a system information message broadcast by the cell.
The apparatus of claim 46, wherein the instructions to identify the information associated with the cell are executable by the processor to cause the apparatus to receive a cell identifier.
The apparatus of claim 49, wherein the instructions to determine the scrambling sequence are executable by the processor to cause the apparatus to:

determine an association between the scrambling sequence and one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence.
The apparatus of claim 50, wherein the instructions are further executable by the processor to cause the apparatus to:

receive a broadcast message indicating a configuration of the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence.
The apparatus of claim 50, wherein a configuration of the association between the scrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the cell identifier, and an index of the preamble sequence is predetermined.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

transmit, to a base station, a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload;

receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

decode control information from the control channel based at least in part on an identifier associated with resources of the first message;

receive, based at least in part on the control information, a downlink data payload of the second message;

determine, based at least in part on the identifier associated with the resources of the first message, a descrambling sequence for the downlink data payload;

descramble the downlink data payload using the descrambling sequence; and

identify that the downlink data payload is associated with the UE based at least in part on information included in the downlink data payload.
The apparatus of claim 53, wherein identifying that the downlink data payload is associated with the UE is based at least in part on at least one of a medium access control (MAC) control element, a MAC header, or the control information.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

transmit, to a base station, a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

decode control information from the control channel based at least in part on the identifier associated with the first message;

receive, based at least in part on the control information, a downlink data payload of the second message;

determine, based at least in part on the identifier associated with the first message, a descrambling sequence for the downlink data payload;

descramble the downlink data payload using the descrambling sequence; and

identify that the downlink data payload is associated with the UE based at least in part on the identifier associated with the first message.
The apparatus of claim 55, wherein the identifier associated with the first message comprises at least a portion of an identifier of the UE.
The apparatus of claim 55, wherein the identifier associated with the first message comprises a scrambling sequence used to scramble the uplink data payload.
The apparatus of claim 57, wherein the identifier associated with the first message is based at least in part on time/frequency resources for transmitting the first message, an index of the preamble sequence, and a cell identifier.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

transmit a first message of a random access channel procedure over a random access resource;

identify a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

monitor for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

decode control information of the second message based at least in part on an identifier associated with the random access resource; and

receive, based at least in part on the control information, a downlink data payload of the second message.
The apparatus of claim 59, wherein the first set of resources comprises a first control resource set and the second set of resources comprises a second control resource set.
The apparatus of claim 59, wherein the first set of resources comprises a first random access response window and the second set of resources comprises a second random access response window that is non-overlapping with the first random access response window.
The apparatus of claim 59, wherein the instructions to identify the configuration are executable by the processor to cause the apparatus to:

receive a message indicating the configuration.
The apparatus of claim 59, wherein the configuration is predetermined.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

transmit a first message of a random access channel procedure over a random access resource;

identify a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

monitor for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

identify an offset for an identifier associated with the random access resource;

decode control information of the second message based at least in part on the identifier and the offset; and

receive, based at least in part on the control information, a downlink data payload of the second message.
The apparatus of claim 64, wherein the offset comprises a first offset associated with the two-step random access channel procedure or a second offset associated with the four-step random access channel procedure.
The apparatus of claim 64, wherein the first set of resources comprises a control resource set and a first random access response window and the second set of resources comprises the control resource set and a second random access response window that is at least partially overlapping with the first random access response window.
The apparatus of claim 64, wherein the instructions to identify the configuration are executable by the processor to cause the apparatus to:

receive a message indicating the configuration.
The apparatus of claim 64, wherein the configuration is predetermined.
An apparatus for wireless communications at a base station, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receive a first message of a two-step random access channel procedure in a cell, the first message comprising a preamble sequence and a scrambled data payload;

identify resources of the first message;

determine a descrambling sequence used to descramble the scrambled data payload based at least in part on information associated with the cell and an identifier associated with the resources; and

descramble the scrambled data payload using the descrambling sequence.
The apparatus of claim 69, wherein the instructions are further executable by the processor to cause the apparatus to:

configure a set of message identifiers for the cell;

transmit a broadcast message indicating an association between each of the set of message identifiers and a respective preamble sequence index; and

determine the descrambling sequence based at least in part on a message identifier of the set of message identifiers associated with the preamble sequence.
The apparatus of claim 70, wherein the broadcast message comprises a system information message broadcast.
The apparatus of claim 69, wherein the instructions are further executable by the processor to cause the apparatus to:

determine a configuration of one or more cell-specific parameters; and

transmit a message indicating the configuration of the one or more cell-specific parameters.
The apparatus of claim 72, wherein the instructions are further executable by the processor to cause the apparatus to:

determine a configuration of an association between the scrambling sequence and one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence.
The apparatus of claim 73, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit a broadcast message indicating the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources of the first message, the one or more cell-specific parameters, and an index of the preamble sequence.
The apparatus of claim 73, wherein the configuration of the association between the descrambling sequence and the one or more of the identifier associated with the resources for transmitting the first message, the one or more cell-specific parameters, and an index of the preamble sequence is predetermined.
An apparatus for wireless communications at a base station, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receive a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload;

encode, based at least in part on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure;

generate, based at least in part on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message;

scramble the downlink data payload using the scrambling sequence; and

transmit, to one or more user equipment (UEs) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
The apparatus of claim 76, wherein the instructions are further executable by the processor to cause the apparatus to:

determine that the downlink data payload is associated with a UE of the one or more UEs; and

transmit information within the downlink data payload that indicates the downlink data payload is associated with the UE.
The apparatus of claim 77, wherein the information within the downlink data payload comprises a medium access control (MAC) control element indicating an identifier of the UE.
An apparatus for wireless communications at a base station, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receive a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

encode, based at least in part on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure;

generate, based at least in part on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message;

scramble the downlink data payload using the scrambling sequence; and

transmit, to a user equipment (UE) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
The apparatus of claim 79, wherein the identifier associated with the first message comprises an identifier of the UE.
The apparatus of claim 79, wherein the identifier associated with the first message comprises a scrambling sequence used to scramble the uplink data payload.
The apparatus of claim 81, wherein the identifier associated with the first message is based at least in part on time/frequency resources for transmitting the first message, an index of the preamble sequence, and a cell identifier.
An apparatus for wireless communications at a base station, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

identify a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

receive a first message of a random access channel procedure over a random access resource;

encode control information based at least in part on an identifier associated with the random access resource; and

transmit a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.
The apparatus of claim 83, wherein the first set of resources comprises a first control resource set and the second set of resources comprises a second control resource set.
The apparatus of claim 83, wherein the first set of resources comprises a first random access response window and the second set of resources comprises a second random access response window that is non-overlapping with the first random access response window.
The apparatus of claim 83, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to one or more user equipment (UEs) , a message indicating the configuration.
An apparatus for wireless communications at a base station, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

identify a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

receive a first message of a random access channel procedure over a random access resource;

determine an offset for the identifier associated with the random access resource;

encode control information based at least in part on the offset and the identifier associated with the random access resource; and

transmit a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.
The apparatus of claim 87, wherein the offset comprises a first offset associated with the two-step random access channel procedure or a second offset associated with the four-step random access channel procedure.
The apparatus of claim 87, wherein the first set of resources comprises a control resource set and a first random access response window and the second set of resources comprises the control resource set and a second random access response window that is at least partially overlapping with the first random access response window.
The apparatus of claim 87, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to one or more user equipment (UEs) , a message indicating the configuration.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for identifying resources of a cell for transmitting a first message of a two-step random access channel procedure;

means for identifying information associated with the cell;

means for determining a scrambling sequence based at least in part on the information associated with the cell and an identifier associated with the resources;

means for scrambling a data payload of the first message using the determined scrambling sequence; and

means for transmitting the first message of the two-step random access channel procedure, the first message comprising a preamble sequence and the scrambled data payload.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for transmitting, to a base station, a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload;

means for receiving, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

means for decoding control information from the control channel based at least in part on an identifier associated with resources of the first message;

means for receiving, based at least in part on the control information, a downlink data payload of the second message;

means for determining, based at least in part on the identifier associated with the resources of the first message, a descrambling sequence for the downlink data payload;

means for descrambling the downlink data payload using the descrambling sequence; and

means for identifying that the downlink data payload is associated with the UE based at least in part on information included in the downlink data payload.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for transmitting, to a base station, a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

means for receiving, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

means for decoding control information from the control channel based at least in part on the identifier associated with the first message;

means for receiving, based at least in part on the control information, a downlink data payload of the second message;

means for determining, based at least in part on the identifier associated with the first message, a descrambling sequence for the downlink data payload;

means for descrambling the downlink data payload using the descrambling sequence; and

means for identifying that the downlink data payload is associated with the UE based at least in part on the identifier associated with the first message.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for transmitting a first message of a random access channel procedure over a random access resource;

means for identifying a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

means for monitoring for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

means for decoding control information of the second message based at least in part on an identifier associated with the random access resource; and

means for receiving, based at least in part on the control information, a downlink data payload of the second message.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for transmitting a first message of a random access channel procedure over a random access resource;

means for identifying a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

means for monitoring for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

means for identifying an offset for an identifier associated with the random access resource;

means for decoding control information of the second message based at least in part on the identifier and the offset; and

means for receiving, based at least in part on the control information, a downlink data payload of the second message.
An apparatus for wireless communications at a base station, comprising:

means for receiving a first message of a two-step random access channel procedure in a cell, the first message comprising a preamble sequence and a scrambled data payload;

means for identifying resources of the first message;

means for determining a descrambling sequence used to descramble the scrambled data payload based at least in part on information associated with the cell and an identifier associated with the resources; and

means for descrambling the scrambled data payload using the descrambling sequence.
An apparatus for wireless communications at a base station, comprising:

means for receiving a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload;

means for encoding, based at least in part on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure;

means for generating, based at least in part on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message;

means for scrambling the downlink data payload using the scrambling sequence; and

means for transmitting, to one or more user equipment (UEs) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
An apparatus for wireless communications at a base station, comprising:

means for receiving a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

means for encoding, based at least in part on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure;

means for generating, based at least in part on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message;

means for scrambling the downlink data payload using the scrambling sequence; and

means for transmitting, to a user equipment (UE) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
An apparatus for wireless communications at a base station, comprising:

means for identifying a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

means for receiving a first message of a random access channel procedure over a random access resource;

means for encoding control information based at least in part on an identifier associated with the random access resource; and

means for transmitting a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.
An apparatus for wireless communications at a base station, comprising:

means for identifying a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

means for receiving a first message of a random access channel procedure over a random access resource;

means for determining an offset for the identifier associated with the random access resource;

means for encoding control information based at least in part on the offset and the identifier associated with the random access resource; and

means for transmitting a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

identify resources of a cell for transmitting a first message of a two-step random access channel procedure;

identify information associated with the cell;

determine a scrambling sequence based at least in part on the information associated with the cell and an identifier associated with the resources;

scramble a data payload of the first message using the determined scrambling sequence; and

transmit the first message of the two-step random access channel procedure, the first message comprising a preamble sequence and the scrambled data payload.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

transmit, to a base station, a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload;

receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

decode control information from the control channel based at least in part on an identifier associated with resources of the first message;

receive, based at least in part on the control information, a downlink data payload of the second message;

determine, based at least in part on the identifier associated with the resources of the first message, a descrambling sequence for the downlink data payload;

descramble the downlink data payload using the descrambling sequence; and

identify that the downlink data payload is associated with the UE based at least in part on information included in the downlink data payload.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

transmit, to a base station, a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

receive, from the base station, a control channel associated with a second message of the two-step random access channel procedure;

decode control information from the control channel based at least in part on the identifier associated with the first message;

receive, based at least in part on the control information, a downlink data payload of the second message;

determine, based at least in part on the identifier associated with the first message, a descrambling sequence for the downlink data payload;

descramble the downlink data payload using the descrambling sequence; and

identify that the downlink data payload is associated with the UE based at least in part on the identifier associated with the first message.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

transmit a first message of a random access channel procedure over a random access resource;

identify a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

monitor for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

decode control information of the second message based at least in part on an identifier associated with the random access resource; and

receive, based at least in part on the control information, a downlink data payload of the second message.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

transmit a first message of a random access channel procedure over a random access resource;

identify a configuration comprising a first set of resources associated with a second message of a two-step random access channel procedure and a second set of resources associated with a second message of a four-step random access channel procedure;

monitor for a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources;

identify an offset for an identifier associated with the random access resource;

decode control information of the second message based at least in part on the identifier and the offset; and

receive, based at least in part on the control information, a downlink data payload of the second message.
A non-transitory computer-readable medium storing code for wireless communications at a base station, the code comprising instructions executable by a processor to:

receive a first message of a two-step random access channel procedure in a cell, the first message comprising a preamble sequence and a scrambled data payload;

identify resources of the first message;

determine a descrambling sequence used to descramble the scrambled data payload based at least in part on information associated with the cell and an identifier associated with the resources; and

descramble the scrambled data payload using the descrambling sequence.
A non-transitory computer-readable medium storing code for wireless communications at a base station, the code comprising instructions executable by a processor to:

receive a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload;

encode, based at least in part on an identifier associated with resources of the first message, control information for a control channel of a second message of the two-step random access channel procedure;

generate, based at least in part on the identifier associated with resources of the first message, a scrambling sequence for a downlink data payload of the second message;

scramble the downlink data payload using the scrambling sequence; and

transmit, to one or more user equipment (UEs) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
A non-transitory computer-readable medium storing code for wireless communications at a base station, the code comprising instructions executable by a processor to:

receive a first message of a two-step random access channel procedure, the first message comprising a preamble sequence and an uplink data payload, the uplink data payload comprising an identifier associated with the first message;

encode, based at least in part on the identifier associated with the first message, control information for a control channel of a second message of the two-step random access channel procedure;

generate, based at least in part on the identifier associated with the first message, a scrambling sequence for a downlink data payload of the second message;

scramble the downlink data payload using the scrambling sequence; and

transmit, to a user equipment (UE) , the second message comprising the scrambled downlink data payload and the control channel including the encoded control information.
A non-transitory computer-readable medium storing code for wireless communications at a base station, the code comprising instructions executable by a processor to:

identify a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

receive a first message of a random access channel procedure over a random access resource;

encode control information based at least in part on an identifier associated with the random access resource; and

transmit a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.
A non-transitory computer-readable medium storing code for wireless communications at a base station, the code comprising instructions executable by a processor to:

identify a configuration comprising a first set of resources associated with a two-step random access channel procedure and a second set of resources associated with a four-step random access channel procedure;

receive a first message of a random access channel procedure over a random access resource;

determine an offset for the identifier associated with the random access resource;

encode control information based at least in part on the offset and the identifier associated with the random access resource; and

transmit a second message of the random access channel procedure based at least in part on the configuration of the first set of resources and the second set of resources, the second message comprising the encoded control information and a downlink data payload.