WO2020150991A1

WO2020150991A1 - Blind secondary cell group configuration in multi-radio access technology-dual connectivity

Info

Publication number: WO2020150991A1
Application number: PCT/CN2019/073123
Authority: WO
Inventors: Peng Cheng; Huichun LIU; Ozcan Ozturk; Gavin Bernard Horn
Original assignee: Qualcomm Incorporated
Priority date: 2019-01-25
Filing date: 2019-01-25
Publication date: 2020-07-30

Abstract

Methods, systems, and devices for wireless communications are described. A user equipment (UE) and/or a master node may use blind configurations to resume communications with one or more cells of a dual connectivity (DC) scheme. In some cases, the blind configuration may be used for a secondary cell group (SCG) of the DC scheme. This blind configuration may include the UE applying a previously stored configuration for the SCG (e. g., including higher-layer and lower-layer configurations of a last serving SN of the DC scheme) if it determines the previously stored configuration is valid. Additionally or alternatively, the blind configuration may include the network using a previous SCG configuration or reconfiguring the SCG and transmitting this indication in a resume communications message to the UE. In some cases, the network may determine this blind configuration based on assistance information from the UE.

Description

BLIND SECONDARY CELL GROUP CONFIGURATION IN MULTI-RADIO ACCESS TECHNOLOGY-DUAL CONNECTIVITY

BACKGROUND

The following relates generally to wireless communications, and more specifically to blind secondary cell group (SCG) configuration in multi-radio access technology-dual connectivity (MRDC) .

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) . A UE may be configured to simultaneously connect to and communicate with a network using multiple cells, such as in dual connectivity (DC) configurations. In some cases, the UE may resume communications with one or more of the cells after a period of inactivity. Techniques to more efficiently resume communications between the UE and network are desired.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support blind secondary cell group (SCG) configuration in multi-radio access technology-dual connectivity (MR-DC) . Generally, the described techniques provide for a user equipment (UE) operating in a dual connectivity (DC) configuration with a master node (MN) and a secondary node (SN) to determine whether a previously stored lower-layer SCG configuration can be used to resume communications with the SN after being in an inactive communications state with the SN. In some cases, the previously stored SCG configuration may be stored at the UE, the MN, or both. When stored at the UE, the UE may determine whether to use its previously stored lower-layer SCG configuration based on a set of validation factors transmitted with a release message that the MN had transmitted to initially transition the UE into the inactive communications state with the SN. For example, the UE may check whether it is in a cell of a validity area associated with the previously stored lower-layer SCG configuration, whether a validity timer has expired for the previously stored lower-layer SCG configuration, whether a measurement for the previously stored lower-layer SCG configuration is above a threshold value, or a combination thereof. If the UE determines the previously stored lower-layer SCG configuration is no longer valid, it may discard the previously stored lower-layer SCG configuration and work with the MN to determine a new configuration to resume communications with the SN. If the UE determines that the previously stored lower-layer SCG configuration is still valid, the UE may use the stored configuration as the UE transitions back to a connected mode with the secondary node. The UE may also notify the MN that the stored SCG configuration is valid.

In some cases, the UE may be unable to store a previously used lower-layer SCG configuration, while the MN may still store a context of the SN with a lower-layer SCG configuration (e.g., a previously stored lower-layer SCG configuration stored at the MN) . As such, the MN may transmit a measurement configuration for the UE to perform measurements on the SCG and indicate for the UE to transmit assistance information based on the measurements. Based on the assistance information from the UE, the MN may then transmit a lower-layer SCG configuration for the UE to establish communications with the SN. In some cases, the assistance information may indicate whether the UE can use the previously stored lower-layer SCG configuration at the MN or needs an updated lower-layer SCG configuration, and the transmitted lower-layer SCG configuration may reflect this indication. The UE may then use this received lower-layer SCG configuration to resume communications with the SN to operate according to the DC configuration. In some cases, the MN may be associated with a first radio access technology (RAT) , and the SN may be associated with a second RAT, indicating a MR-DC configuration for communications between the UE, MN, and SN.

A method of wireless communications at a UE is described. The method may include identifying that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN, determining that SN communications are to resume, determining whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications, and transmitting an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications.

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 that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN, determine that SN communications are to resume, determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications, and transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for identifying that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN, determining that SN communications are to resume, determining whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications, and transmitting an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications.

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 that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN, determine that SN communications are to resume, determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications, and transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, with a release message instructing the UE to enter the inactive communications state, an indication that the UE may be to store a lower-layer SCG configuration, and storing the lower-layer SCG configuration such that the lower-layer SCG configuration becomes the previously stored lower-layer SCG configuration.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining whether the previously stored lower-layer SCG configuration can be used for the resumption of SN communications may include operations, features, means, or instructions for identifying, from information included with the release message, a validity area which defines one or more cells in which the previously stored lower-layer SCG configuration may be valid for use, and determining whether the UE may be within the one or more cells defined by the validity area.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the validity area includes a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a radio access network (RAN) notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining whether the previously stored lower-layer SCG configuration can be used for the resumption of SN communications may include operations, features, means, or instructions for identifying, from information included with the release message, a validity time which defines a period in which the previously stored lower-layer SCG configuration may be valid, and determining whether the previously stored lower-layer SCG configuration may be valid based on the validity timer.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining whether the previously stored lower-layer SCG configuration can be used for the resumption of SN communications may include operations, features, means, or instructions for identifying, from information included with the release message, a threshold measurement value, measuring signal reception conditions for comparison with the threshold measurement value, and determining whether the previously stored lower-layer SCG configuration may be valid based on the UE measurements satisfying the threshold measurement value.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the threshold measurement value includes a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for discarding the previously stored lower-layer SCG configuration based on determining that the SCG configuration not being valid.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, with a release message instructing the UE to enter the inactive communications state, a measurement configuration for a SCG including the SN of the DC configuration.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining whether the previously stored lower-layer SCG configuration can be used for the resumption of SN communications may include operations, features, means, or instructions for performing measurements in accordance with the measurement configuration, and determining whether to include the indication that the previously stored lower-layer SCG configuration may be available for resuming the SN communications based on the measurements.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, from the MN and in response to the indication, a lower-layer secondary cell configuration to be used by the UE for SN communications, where the lower-layer secondary cell configuration may be either the previously stored lower-layer SCG configuration, as stored by the MN, or an updated lower-layer SCG configuration.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the lower-layer SCG configuration may include operations, features, means, or instructions for receiving the lower-layer SCG configuration in a resume communications message or a reconfiguration message.

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 the MN and in addition to transmission of the indication, assistance information based on the measurements made in accordance with the measurement configuration, where the assistance information includes information to assist the MN in determining whether to apply the previously stored lower-layer SCG configuration or the updated lower-layer SCG configuration.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for storing a higher-layer SCG configuration based on receiving a release message.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MN operates in a first RAT and the SN operates in a second RAT.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the lower-layer SCG configuration includes at least one of an identifier for the SN of the DC configuration, parameters for the SN communications, or configuration information for one or more cells of the SCG.

A method of wireless communications at a base station is described. The method may include identifying that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE, transmitting, to the UE, a release message indicating a suspension of SN communications for the UE, storing, at the MN, a lower-layer SCG configuration used for the SN communications by the UE, receiving a message from the UE that the SN communications are to resume, and receiving an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications.

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 that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE, transmit, to the UE, a release message indicating a suspension of SN communications for the UE, store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE, receive a message from the UE that the SN communications are to resume, and receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for identifying that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE, transmitting, to the UE, a release message indicating a suspension of SN communications for the UE, storing, at the MN, a lower-layer SCG configuration used for the SN communications by the UE, receiving a message from the UE that the SN communications are to resume, and receiving an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications.

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 that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE, transmit, to the UE, a release message indicating a suspension of SN communications for the UE, store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE, receive a message from the UE that the SN communications are to resume, and receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the release message may include operations, features, means, or instructions for transmitting, to the UE, an indication to store the lower-layer SCG configuration.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting with the indication to store the lower-layer SCG configuration, information including a validity area which defines one or more cells in which the UE may be to be located if the stored lower-layer SCG configuration may be to be valid.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the validity area of the one or more cells in the SCG includes a list of the one or more cells, a PCI list of the one or more cells, an RNA list of the one or more cells, a TA list of the one or more cells, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting with the indication to store the lower-layer SCG configuration, information including a validity timer which defines a timing for when the stored lower-layer SCG configuration may be valid.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting with the indication to store the lower-layer SCG configuration, information including a threshold measurement value to allow the UE to determine whether the stored lower-layer SCG configuration may be to be applied.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the threshold measurement value includes an RSRP measurement, an RSRQ measurement, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for discarding the stored lower-layer SCG configuration based on receiving the indication from the UE that the stored SCG configuration may be not to be used.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the release message may include operations, features, means, or instructions for transmitting, to the UE, a measurement configuration for a SCG including a SN of the DC configuration, where the indication from the UE whether the stored lower-layer SCG configuration may be to be used for the SN communications may be received based on the measurement configuration.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, from the UE, assistance information based on transmitting the measurement configuration, where the assistance information includes an indication to apply the stored lower-layer SCG configuration for the UE to use for SN communications or an identifier of a primary secondary cell (PSCell) for the UE to use for the SN communications, and transmitting, to the UE, a lower-layer configuration for the SCG for the SN communications based on the assistance information.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the lower-layer configuration for the SCG may be transmitted in a resume communications message or a reconfiguration message.

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 a SN of the DC configuration, an activation request message for the SN communications based on receiving the message from the UE that the SN communications may be to resume, and transmitting, to the UE, a resume communications message for the SN communications based on receiving the indication from the UE whether the stored lower-layer SCG configuration may be to be used for the SN communications, where the resume communications message and the activation request message may be transmitted simultaneously.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for initiating a validity timer based on transmitting the release message, determining that the validity timer expires prior to receiving the message from the UE that the SN communications may be to resume, and discarding the stored lower-layer SCG configuration used for the SN communications by the UE based on the validity timer expiring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communications that supports blind secondary cell group (SCG) configuration in multi-radio access technology-dual connectivity (MR-DC) in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIGs. 3 through 9 illustrate examples of process flows that support blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIGs. 10 and 11 show block diagrams of devices that support blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIG. 12 shows a block diagram of a UE communications manager that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIG. 13 shows a diagram of a system including a device that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIGs. 14 and 15 show block diagrams of devices that support blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIG. 16 shows a block diagram of a base station communications manager that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIG. 17 shows a diagram of a system including a device that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

FIGs. 18 through 23 show flowcharts illustrating methods that support blind SCG configuration in MR-DC in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

In some wireless communications systems, a user equipment (UE) may communicate with a network using dual connectivity (DC) . In such cases, the UE may simultaneously communicate with different base stations, where a first base station may provide a first cell and be referred to as a master node (MN) . Likewise, a second base station providing a second cell of the DC deployment may be referred to as a secondary node (SN) , and the first and second cells may each be associated with a same or different radio access technology (RAT) . As such, various DC deployments may be referred to as evolved universal terrestrial radio access (E-UTRA) new radio (NR) -dual connectivity (EN-DC) , NR E-UTRA-DC (NE-DC) , NR NR-DC, Long Term Evolution (LTE) LTE-DC, or may include other types of multi-radio access technology-dual connectivity (MR-DC) deployments based on the RAT implemented by each cell. In any case, the different cells a UE communicates on for DC may use the same or different radio frequency (RF) spectrum bands.

Additionally or alternatively, a UE may communicate with a single base station using multiple carriers (e.g., component carriers (CCs) ) . In such cases, a CC may refer to each of the carriers used by a UE in carrier aggregation (CA) operations. Further, a serving cell of a base station may correspond to each CC used in CA operation, where each serving cell may be different (e.g., based on the path loss experienced by different CCs on different RF spectrum bands) . In some examples, one carrier may be designated as a primary carrier, or primary CC (PCC) , for the UE, which may be served by a primary cell (PCell) . Additional carriers may be designated as secondary carriers, or secondary CCs (SCCs) , which may be served by secondary cells (SCells) of the base station. CA operations may also use the same or different RF bands for communications.

In some cases, a UE may not be continuously communicating with one or more base stations, and the UE may accordingly operate in various communication states, for example, to save power when not transmitting or receiving data. For instance, the UE may operate in an idle communication state (e.g., a radio resource control (RRC) idle state) , where the UE may be “on standby” and thus, may not be assigned to a particular serving base station. Additionally, the UE may operate in a connected communication state (e.g., an RRC connected state) where the UE may be “active” and transmit data to/receive data from a serving cell. The UE may accordingly transition from the RRC idle state to the RRC connected state, and vice versa, based on its activity.

In some systems, a UE may support additional communication states. For example, an inactive communication state (e.g., an RRC inactive state) between the connected communication state and the idle communication state may be used to enable transitions from the inactive communication state to the connected communication state with reduced latency (e.g., as compared to the transition from the idle communication state to the connected communication state) . When transitioning to the inactive communication state, a UE context (e.g., an access stratum (AS) context) may be retained at the UE and the network (e.g., radio access network (RAN) ) , and both the UE and network may further store higher-layer configurations (e.g., for respective cells of DC/CA deployments) while simultaneously releasing lower-layer configurations (as the lower-layer configurations may change, for example, due to the UE’s mobility) . Then, when resuming communications with the network and moving out of the inactive communication state, the UE may apply the stored higher-layer configurations.

However, due to the release of the lower-layer configurations, the UE may not be able to operate using the previously-established DC and/or CA schemes immediately after leaving the inactive communication state. For example, a UE in a DC deployment that enters the inactive communication state may later require multiple reconfiguration messages to obtain a full configuration, including the lower-layer configurations for different cells (and any updates thereto) , to establish communication with multiple nodes of the DC deployment. Additionally, the UE may be asked to perform and transmit one or more measurement reports to reestablish communications with a previous cell of the DC scheme or establish connections with a new cell according to the DC scheme. Further, the full lower-layer configurations for each cell may need to be signaled from the network. Such signaling overhead and measurement reporting may reduce efficiency in the system and may cause unnecessary delays in configuring a UE for CA/DC communications.

As described herein, techniques for storing lower-layer configurations may reduce latency and signaling overhead when the UE leaves the inactive communication state. For example, the UE and network may use a blind configuration to resume or establish communications with one or more cells of a DC scheme based on assistance information from the UE. In some cases, the blind configuration may be used for a secondary cell group (SCG) of the DC scheme. This blind configuration may include the UE applying a previously stored context for the SCG (e.g., including higher-layer and lower-layer configurations of a last serving SN of the DC scheme) . Additionally or alternatively, the blind configuration may include the network blindly reconfiguring the SCG and transmitting this indication in a resume communications message (e.g., RRC resume message) to the UE. Accordingly, the assistance information from the UE may include an indication of whether the UE can apply a stored configuration of its last serving SN or whether the network can blindly reconfigure the SCG for the UE with a last serving SCG configuration for the UE (e.g., if the UE has not stored its SCG configuration) . As such, in some cases, the network may store a context for the SN (e.g., including a lower-layer configuration for the SCG) , enabling it to simultaneously transmit the resume communications message to the UE and an SN activation request message to the SN.

The storage of the lower-layer configurations and the use of the blind configurations may reduce signaling overhead used to fully configure one or more cells for a UE.The described techniques may accordingly be applicable for DC configurations (e.g., NE-DC, EN-DC, and the like) and CA configurations when the UE resumes from an inactive communication state. Additionally or alternatively, the described techniques may be applicable to scenarios where a UE is connected to a single base station, and may be used to efficiently set up DC or CA when the UE resumes communications from the inactive communication state.

Aspects of the disclosure are initially described in the context of a wireless communications system. Additional aspects of the disclosure are illustrated through an additional wireless communications system and examples of process flows. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to blind SCG configuration in MR-DC.

FIG. 1 illustrates an example of a wireless communications system 100 that supports blind SCG configuration in MR-DC 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 an LTE network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or an 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.

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.

A service data application protocol (SDAP) may be associated with mapping bearers of a network. For example, the SDAP may map radio bearers based on quality of service (QoS) requirements. In such cases, packets (e.g., IP packets) may be mapped to different radio bearers in accordance with the QoS of the packets. Following the mapping to a radio bearer, the packets may be passed to the PDCP protocol layer. In some examples, the SDAP protocol layer may indicate a QoS flow identifier for uplink and downlink packets.

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 CA 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 CA configuration. Carrier aggregation may be used with both FDD and TDD component carriers.

Wireless communications system 100 may support the storage of lower-layer configurations used in DC and/or CA deployments to enable the efficient transition from an RRC inactive state. Further, signaling that indicates a difference between the stored lower-layer configurations and updated lower-layer configurations (e.g., delta signaling) after exiting the RRC inactive state may reduce signaling overhead in the system.

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.

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 a master information block (MIB) , which may be transmitted in the PBCH. The MIB may contain system bandwidth information, an SFN, and a physical HARQ indicator channel (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 random access channel (RACH) procedures, paging, physical uplink control channel (PUCCH) , physical uplink shared channel (PUSCH) , power control, sounding reference signal (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 downlink 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 (e.g., 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 synchronizing (e.g., the connecting device decodes SIB2) , the connecting device may perform a random access channel (RACH) procedure to further establish the connection to the wireless access network through the serving device. The RACH procedure may involve the connecting device transmitting a message including a RACH preamble (e.g., a message 1 (Msg1) ) on a set of selected resources to inform the serving device about its presence. For example, the RACH preamble may be randomly selected from a set of 64 predetermined sequences. This may enable the serving device to distinguish between multiple connecting devices trying to access the system simultaneously. Additionally, the connecting device may receive uplink synchronization and may request resources for further communications in Msg1. After receiving Msg1 and in response to Msg1, the serving device may transmit a random access response (RAR) (e.g., a message 2 (Msg2) ) to the connecting device, where the serving device identifies the connecting device based on the RACH preamble transmitted. Msg2 may provide an uplink resource grant, a timing advance, and a temporary cell radio network temporary identity (C-RNTI) .

The connecting device may then transmit an RRC connection request, or RACH message 3 (Msg3) , along with a temporary mobile subscriber identity (TMSI) (e.g., if the connecting device has previously been connected to the same wireless network) or a random identifier, after receiving the RAR. The RRC connection request may also indicate the reason the connecting device is connecting to the network (e.g., emergency, signaling, data exchange) . The serving device may respond to the connection request with a contention resolution message, or RACH message 4 (Msg4) , addressed to the connecting device, which may provide a new C-RNTI. If the connecting device receives a contention resolution message with the correct identification, it may proceed with RRC setup. If the connecting device does not receive a contention resolution message (e.g., if there is a conflict with another connecting device) , it may repeat the RACH process by transmitting a message with 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 some wireless communications systems, a UE 115 may be in various states (e.g., RRC states) of being connected to a base station 105 or the network. For example, the UE 115 may operate in an idle communication state (e.g., a radio resource control (RRC) idle state) , where the UE 115 may be “on standby” and thus, may not be assigned to a particular serving base station. Additionally, the UE 115 may operate in a connected communication state (e.g., an RRC connected state) where the UE 115 may be “active” and transmit data to/receive data from a serving cell. The UE 115 may accordingly transition from the RRC idle state to the RRC connected state, and vice versa, based on its activity.

In some cases, an additional state may be used for the UE 115 that is an intermediary between the idle communication state and the connected communication state. For example, an inactive communication state (e.g., an RRC inactive state) between the connected communication state and the idle communication state may be used to enable transitions from the inactive communication state to the connected communication state with reduced latency (e.g., as compared to the transition from the idle communication state to the connected communication state) . When transitioning to the inactive communication state, a UE context (e.g., an AS context) may be retained at the UE 115 and the network (e.g., the base station 105, the RAN, etc. ) , and both the UE 115 and network may further store higher-layer configurations (e.g., for respective cells of DC/CA deployments) while simultaneously releasing lower-layer configurations (as the lower-layer configurations may change, for example, due to the UE’s mobility) . Then, when resuming communications with the network and moving out of the inactive communication state, the UE 115 may apply the stored higher-layer configurations.

However, due to the release of the lower-layer configurations, the UE may not be able to operate using the previously-established DC and/or CA schemes immediately after leaving the inactive communication state. For example, a UE 115 in a DC deployment that enters the inactive communication state may later require multiple reconfiguration messages to obtain a full configuration, including the lower-layer configurations for different cells (and any updates thereto) , to establish communication with multiple nodes of the DC deployment. Additionally, the UE 115 may be asked to perform and transmit one or more measurement reports for the different cells to reestablish communications with a previous cell of the DC scheme or establish connections with a new cell according to the DC scheme. Further, the full lower-layer configurations for each cell may need to be signaled from the network. Such signaling overhead may reduce efficiency in the system and may cause unnecessary delays in configuring a UE for CA/DC communications.

Wireless communications system 100 may support efficient techniques for using blind configurations to resume or establish communications with one or more cells of a DC scheme based on assistance information from the UE 115. In some cases, the blind configuration may be used for an SCG (e.g., cells associated with a SN) of the DC scheme. This blind configuration may include the UE 115 applying a previously stored context for the SCG (e.g., including higher-layer and lower-layer configurations of a last serving SN of the DC scheme) . Additionally or alternatively, the blind configuration may include the network blindly reconfiguring the SCG and transmitting this indication in a resume communications message (e.g., RRC resume message) to the UE 115. Accordingly, the assistance information from the UE 115 may include an indication of whether the UE 115 can apply a stored configuration of its last serving SN or whether the network can blindly reconfigure the SCG for the UE 115 with a last serving SCG configuration for the UE 115 (e.g., if the UE 115 has not stored its SCG configuration) . As such, in some cases, the network may store a context for the SN (e.g., including a lower-layer configuration for the SCG) , enabling it to simultaneously transmit the resume communications message to the UE 115 and an SN activation request message to the SN.

FIG. 2 illustrates an example of a wireless communications system 200 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, wireless communications system 200 may implement aspects of wireless communications system 100. For example, wireless communications system 200 includes a first base station 105-a, a second base station 105-b, and a UE 115-a, which may be examples of the corresponding devices described with reference to FIG. 1. Wireless communications system 200 may support the use of techniques that enhance the resumption of communications in CA and DC deployments after UE 115-a leaves an RRC inactive state.

In wireless communications system 200, a UE 115-a may communicate with a network using a DC configuration. In such cases, UE 115-a may simultaneously communicate with different base stations 105 (e.g., first base station 105-a and second base station 105-b) . First base station 105-a may provide coverage to a first cell 205-a and first base station 105-a may be referred to as an MN. The first cell 205-a may correspond to a PCell in the DC deployment. Additionally, second base station 105-b may provide coverage to a second cell 205-b of the DC configuration, and second base station 105-b may be referred to as an SN. In some cases, the second cell 205-b may correspond to a PSCell in the DC deployment. Additional SCells may be used by each base station 105, where cells associated with the MN may correspond to a master cell group (MCG) and cells associated with the SN may correspond to an SCG.

In some cases, each of the cells 205 of the DC deployment may be associated with a same or different RAT. For instance, first base station 105-a and second base station 105-b may communicate using a first RAT and a second RAT, respectively. The first RAT and/or the second RAT may include, for example, LTE, NR, or another RAT. As such, various DC deployments may sometimes be referred to as EN-DC, NE-DC, NR NR-DC, LTE LTE-DC, enhanced LTE (eLTE) eLTE-DC, or may include other types of MR-DC deployments based on the RAT that is used by each base station 105. In any case, the different cells of a DC deployment may use the same or different RF spectrum bands for communication with UE 115-a.

In some cases, DC deployments may use different radio bearers for transmitted messages for each cell. For instance, first base station 105-a may be configured as a MN and may provide a set of serving cells that correspond to an MCG. First base station 105-a may use a first set of signaling radio bearers (SRBs) (e.g., SRB1, SRB2) to transport messages for the MCG, such as RRC messages. Additionally, second base station 105-b may be configured as an SN and may provide another set of serving cells that correspond to an SCG, and second base station 105-b may use a second set of SRBs (e.g., SRB3) to transport messages for the SCG. In some examples, a split bearer configuration may be supported, where a particular protocol layer (e.g., a PDCP layer) for both the MN and SN may be used to route data streams to/from UE 115-a. Here, an SRB (e.g., SRB1/SRB2) may be split between the MN and the SN, and downlink messages sent from the MN to UE 115-a may be sent via lower layers (RLC, MAC, PHY, etc. ) of either the MN or the SN. In other cases, downlink messages may be sent via the lower layers of both the master and SNs. In the uplink, RRC messages from UE 115-a may be transmitted to the MN via the SN using the split bearer (e.g., via a “leg” associated with the SN) . For the signaling of data in the user plane, respective data radio bearers (DRBs) may be used by the MCG and SCG.

UE 115-a may also communicate with a single base station 105 (e.g., first base station 105-a) using multiple carriers (e.g., CCs, which may also be referred to as layers, channels, etc. ) . In such cases, a CC may refer to each of the carriers used by UE 115-a in CA operations. Further, a serving cell of first base station 105-a may correspond to each CC used in CA operation, where each serving cell may be different (e.g., based on the path loss experienced by different CCs on different RF spectrum bands) . In some examples, one carrier may be designated as a primary carrier, or primary CC (PCC) , for UE 115-a, which may be served by a PCell. Additional carriers may be designated as secondary carriers, or secondary CCs (SCCs) , which may be served by SCells of first base station 105-a. CA operations may use the same or different RF bands for communications.

In wireless communications system 200, UE 115-a may operate in different RRC states when communicating with one or more of the base stations 105. For instance, and as illustrated by state diagram 210, UE 115-a may operate in an RRC connected state 215 (e.g., RRC_CONNECTED) where UE 115-a may be “active” and transmit data to/receive data from a serving cell. Additionally, UE 115-a may operate in an RRC idle state 220 (e.g., RRC_IDLE) , in which case UE 115-a may be “on standby” and thus, may not be assigned to a particular serving base station 105. In the RRC idle state 220, radio bearers for the system may be released (e.g., to avoid re-routing should UE 115-a move to another cell) , but UE 115-a may still perform various functions, such as cell reselection and discontinuous reception (DRX) for page messages, among other functions. UE 115-a may accordingly transition from the RRC idle state 220 to the RRC connected state 215, and vice versa, based on its activity. When transitioning to the RRC connected state 215 from the RRC idle state 220, UE 115-a may transmit, to a base station 105, a setup request message (e.g., RRCSetupRequest) . Alternatively, when transitioning from the RRC connected state 215 to the RRC idle state 220, UE 115-a may receive a release message (e.g., RRCRelease) .

In wireless communications system 200, UE 115-a may support an additional RRC state. For example, an RRC inactive state 225 between the RRC connected state 215 and the RRC idle state 220 may be used to enable a faster transition to the RRC connected state 215 (e.g., as compared to the transition from the RRC idle state 220 to the RRC connected state 215) . When UE 115-a is in the RRC inactive state 225, it may receive system information, perform cell measurements, and perform other functions. UE 115-a may transition to the RRC connected state 215 from the RRC inactive state 225 when downlink data is available for UE 115-a, or UE 115-a has uplink data to transmit, or both, and UE 115-a may accordingly transmit a resume request message (e.g., RRCResumeRequest) to resume communications with a base station 105. When transitioning from the RRC connected state 215 to the RRC inactive state 225, UE 115-a may receive a release message (e.g., RRCRelease) from a base station 105. Likewise, when moving from the RRC inactive state 225 to the RRC idle state 220, UE 115-a may receive a release message from the base station 105.

When entering into the RRC inactive state 225, a UE context (e.g., an AS context) may be retained at UE 115-a and the network, and both UE 115-a and the network may store higher-layer configurations (e.g., for a DC/CA deployment) while simultaneously releasing lower-layer configurations (as the lower-layer configurations may change, for example, due to UE 115-a being mobile (i.e., non-stationary) ) . More specifically, UE 115-a, first base station 105-a (e.g., providing the MCG) , and second base station 105-b (e.g., providing the SCG) may store PDCP/SDAP configurations (e.g., for both MCG and SCG) when UE 115-a transitions to the RRC inactive state 225. Additionally, UE 115-a may release lower-layer configurations for both the MCG and SCG when in the RRC inactive state 225. Then, when resuming communications with either first base station 105-a or second base station 105-b when moving out of the RRC inactive state 225 to the RRC connected state 215, UE 115-a may apply the stored upper-layer (PDCP and/or SDAP) configurations of the MCG and SCG.

However, due to the release of the lower-layer configurations, UE 115-a may not be able to immediately operate using DC (or CA) communications after transitioning from the RRC inactive state 225. For example, when entering the RRC inactive state 225, UE 115-a may later require multiple reconfiguration messages (e.g., RRC Reconfiguration messages) to obtain a full configuration, including the lower-layer configurations for the MCG and SCG (and any updates thereto) , to establish communication with first base station 105-a and/or second base station 105-b (or another, different, base station 105) of the DC deployment. Additionally, UE 115-a may be asked to perform and transmit one or more measurement reports for the MCG and/or SCG to reestablish communications with a previous cell (e.g., first base station 105-a and/or second base station 105-b) of the DC scheme or establish connections with a new cell (e.g., a new base station 105) according to the DC scheme. This signaling overhead and measurement reports may reduce efficiency in the system through added delays in resuming and/or modifying the DC configuration that UE 115-a operated with prior to entering into the RRC inactive state 225. CA operations may be similarly affected when transitioning out of the RRC inactive state 225.

As described herein, techniques for using blind configurations to resume or establish communications with one or more cells of a DC scheme based on assistance information from UE 115-a. In some cases, the blind configuration may be used for the SCG (e.g., cells associated with the SN, second base station 105-b, etc. ) of the DC scheme. This blind configuration may include UE 115-a applying a previously stored context for the SCG (e.g., including higher-layer and lower-layer configurations of a last serving SN of the DC scheme) . Additionally or alternatively, the blind configuration may include the network (e.g., MN, first base station 105-a, a cell in the MCG, etc. ) blindly reconfiguring the SCG and transmitting an indication of this reconfiguration in a resume communications message (e.g., RRC resume message) to UE 115-a. Accordingly, the assistance information from UE 115-a may include an indication of whether UE 115-a can apply a stored configuration of its last serving SN or whether the network can blindly reconfigure the SCG for UE 115-a with a last serving SCG configuration for UE 115-a (e.g., if UE 115-a has not stored its SCG configuration) . As such, in some cases, the network may store a context for the SN (e.g., including a lower-layer configuration for the SCG) , enabling it to simultaneously transmit the resume communications message to UE 115-a and an SN activation request message to the SN (e.g., second base station 105-b) .

In some aspects with respect to wireless communications system 200, when UE 115-a receives the release message (e.g., RRCRelease message) to transition to the RRC idle state 220, the release message may further include an indication for UE 115-a to suspend communications with second base station 105-b (e.g., SCG, SN, etc. ) . To enable communications to be resumed with second base station 105-b (e.g., or an additional base station 105 for the SCG) , various information elements (IEs) may be transmitted within the release message as well. These IEs may include an indication for UE 115-a to store a lower-layer configuration for the SCG (e.g., an indication-store-SCG-configuration IE) , a list of cells for which the stored SCG configuration is valid (e.g., a validity-area IE) , a timer for how long the stored SCG configuration is valid (e.g., a validity-timer IE) , and a threshold quality measurement for which the stored SCG configuration is valid (e.g., threshold IE) . Accordingly, based on the indication to store the lower-layer SCG configuration, UE 115-a may store both the lower-layer configuration, as well as the higher-layer configuration as described above when entering the RRC inactive state 225.

After being in the RRC inactive state 225, UE 115-a may perform a RACH procedure to re-enter the RRC connected state 215 (e.g., with second base station 105-b) . For example, UE 115-a may first transmit a Msg1 of a four-step RACH procedure as described above to first base station 105-a to initiate the RACH procedure. After receiving a Msg2 (e.g., RAR message) , UE 115-a may validate the stored lower-layer SCG configuration (e.g., based on the validity-are, validity-timer, and threshold IEs) . Subsequently, in Msg3 of the RACH procedure, UE 115-a may indicate whether the stored lower-layer SCG configuration is validated and can be resumed for DC communications with second base station 105-b (e.g., or another SN) .

First base station 105-a may then transmit a Msg4 of the RACH procedure to resume the RRC connection with UE 115-a and may simultaneously transmit an activation request to second base station 105-b based on storing the context of second base station 105-b (e.g., including the SCG lower-layer configuration) . After receiving Msg4 and then transmitting Msg5 to complete the resuming of the RRC connection with first base station 105-a, UE 115-a may then perform a RACH procedure with a PSCell of second base station 105-b. Upon a successful RACH procedure at the PSCell, UE 115-a may resume its connection with both first base station 105-a (e.g., MN) and second base station 105-b (e.g., SN) . In some cases, UE 115-a may apply or replace some lower-layer configuration parameter for the SCG based on broadcasted information in SIBs from second base station 105-b.

Additionally or alternatively, UE 115-a may be unable to store the SCG lower-layer configuration internally (e.g., due to memory limitations) . Accordingly, based on this limitation, first base station 105-a may include an additional SCG measurement configuration IE when transmitting the release message to transition to the RRC connected state 215, where UE 115-a measures one or more cells associated with second base station 105-b (e.g., SN) based on the SCG measurement configuration. In some cases, when the SCG measurement configuration IE is transmitted, the indication for UE 115-a to store the lower-layer configuration for the SCG may be set to false (e.g., to indicate to UE 115-a to not store the lower-layer SCG configuration) . Based on the SCG measurement configuration, UE 115-a may then measure and validate one or more of the cells based on the additional IEs included with the release message (e.g., validity-are, validity-timer, and threshold IEs) . In a Msg3 of a RACH procedure with first base station 105-a, UE 115-a may include UE assistance information based on the measurements according to the SCG measurement configuration and indicate whether to apply a previously used lower-layer SCG configuration stored at first base station 105-a for UE 115-a or indicate a suggested PSCell identifier for second base station 105-b for subsequent communications.

According to the UE assistance information (e.g., from the SCG measurement information) , first base station 105-a may then transmit an SN activation request to second base station. If the SN activation request is acknowledged by second base station 105-b, first base station 105-a may consequently transmit a lower-layer SCG configuration for second base station 105-b to UE 115-a in a Msg4 of the RACH procedure. Additionally or alternatively, first base station 105-a may transmit the lower-layer SCG configuration to UE 115-a in a reconfiguration message (e.g., RRCReconfiguration message) . Based on this lower-layer SCG configuration, UE 115-a may then perform a RACH procedure with second base station 105-b and, if successful, may resume communications with first base station 105-a (e.g., MN) and second base station 105-b (e.g., SN) .

The storage of the lower-layer configurations and the use of the blind configurations may reduce signaling overhead needed to fully configure one or more cells for the DC deployment. For example, the blind configurations may be used for additional cells outside of the SCG. The described techniques may accordingly be applicable for DC configurations (e.g., NE-DC, EN-DC, or the like) when UE 115-a resumes communications from an RRC inactive state 225. Similarly, the described techniques may be applied to CA configurations when UE 115-a transitions out of the RRC inactive state 225. Additionally or alternatively, the described techniques may be applicable to scenarios where UE 115-a is connected with a single base station to efficiently set up DC or CA when UE 115-a resumes communications from an RRC inactive state 225.

FIG. 3 illustrates an example of a process flow 300 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, process flow 300 may implement aspects of wireless communications systems 100 and/or 200. Process flow 300 may include a UE 115-b and a base station 105-c (e.g., network) , which may be examples of corresponding devices as described above with reference to FIGs. 1 and 2. In some cases, process flow 300 may illustrate signaling back and forth between UE 115-b and base station 105-c for a CA configuration that includes two RATs for the different cells (e.g., LTE euCA) . For example, base station 105-c may include a PCell for UE 115-b according to the CA configuration. Additionally, the signaling as shown between UE 115-b and base station 105-c may reduce latency for configuring an SCell (e.g., associated with base station 105-c or with another base station 105) for the CA configuration. For example, process flow 300 may include early measurement reporting that enable the SCell configuration faster for the CA configuration (e.g., compared with previous CA configuration setups) . Additionally, this SCell configuration may be implemented for a UE 115 that is in an idle communication state as described above.

At 305, base station 105-c may transmit a SIB2 to UE 115-b as part of the synchronization process as described above. In some cases, the SIB2 may also indicate for UE 115-b to perform measurements when in the idle communication state. For example, this indication to perform the measurements may be included in an idle mode measurements message (e.g., idleModeMeasurements message set to ‘true’ ) in the SIB2.

At 310, base station 105-c may transmit a SIB5 to UE 115-b that provides a measurement configuration of a potential SCell (s) for the CA configuration. In some cases, this measurement configuration may include an EARFCN and/or a cell list with the potential SCells.

Additionally or alternatively to transmitting the SIB5 at 310, at 315, base station 105-c may transmit an RRC release message to UE 115-b that includes a dedicated measurement configuration for UE 115-b to measure potential SCell (s) for the CA configuration. In some cases, based on the RRC release message, UE 115-b may be configured with a new timer (e.g., a timer 331) with a duration (e.g., up to five (5) minutes) to control how long UE 115-b can perform measurements while in the idle communication state (e.g., idle mode measurements) . The timer may reduce power consumption at UE 115-b by limiting how long it performs the idle mode measurements. In some cases, the dedicated measurement configuration included in the RRC release message may be used by UE 115-b when received, while the measurement configuration included in the SIB5 at the 310 may be used as a fallback. For example, if UE 115-b moves to a new cell different from the one sending the RRC release message (e.g., base station 105-c) , UE 115-b may not receive the RRC release message, but may receive the SIB5 based on synchronizing with the new cell and use that measurement configuration rather than the dedicated measurement configuration.

UE 115-b may then transition from the idle communication state to a connected communication state as described above with reference to FIG. 2. As such, UE 115-b may perform a RACH procedure with base station 105-c based on entering the connected communication state. For example, at 320, UE 115-b may transmit a Msg1 of the RACH procedure, including a physical RACH (PRACH) preamble. At 325, base station 105-c may then transmit Msg2 of the RACH procedure, including the RAR to the Msg1. Then, at 330, UE 115-b may transmit a Msg3 of the RACH procedure to request an RRC connection, and at 335, base station 105-c may transmit a Msg4 of the RACH procedure to setup an RRC connection with UE 115-b. In some cases, Msg4 may be transmitted on an SRB1 for the RACH procedure.

Prior to and during the RACH procedure, while in the idle communication state, UE 115-b may perform the measurements for the potential SCell (s) based on the configuration received in either the SIB5 or the RRC release message. Accordingly, when transmitting a fifth message (Msg5) of the RACH procedure to complete the RRC connection setup with base station 105-c, UE 115-b may also provide an indication of the availability of measurement reports to base station 105-c. For example, UE 115-b may transmit the indication of the availability of the measurement reports in an idle measurements available message (e.g., idleMeasAvailable message set to ‘true’ ) .

At 345 and 350, base station 105-c and UE 115-b may establish and activate an AS security context based on an RRC security mode command transmitted by base station 105-c and a RRC security mode complete message transmitted by UE 115-b in response. These two security mode messages may be referred to as a security mode command (SMC) for the AS security activation.

Once the AS security is established between base station 105-c and UE 115-b, base station 105-c may request UE 115-b to report the measurements for the potential SCell (s) at 355. For example, the request to report the measurements may be included in an idle mode measurement request message (e.g., idleModeMeasurementReq message set to ‘true’ ) . Accordingly, at 360, UE 115-b may transmit the measurement reports in an uplink information response message. For example, the measurement reports may be included in an idle measurement results message (e.g., MeasResultsIdle message) . In some cases, this measurement reporting may occur after the SMC is completed.

After receiving the measurement reports, at 365, base station 105-c may transmit an RRC connection reconfiguration message that includes a configuration for an SCell to establish the CA configuration. In some cases, the SCell configuration may include further configurations for an SRB2 or DRB for communications with the SCell. Subsequently, at 370, UE 115-b may transmit an RRC connection reestablishment reconfiguration complete message to complete the reconfiguration in order to communicate according to the CA configuration. At 375, base station 105-c may transmit a MAC-CE based SCell activation message to complete the CA setup and activate communications with a PCell on base station 105-c and an SCell (e.g., on base station 105-c or another base station 105) for the CA configuration.

FIG. 4 illustrates an example of a process flow 400 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, process flow 400 may implement aspects of wireless communications systems 100 and/or 200. Process flow 400 may include a UE 115-c, a last serving MN 405, and an SN 410. UE 115-c may be an example of a UE 115 as described above with reference to FIGs. 1-3. Last serving MN 405 may be an example of a base station 105, MN, MCG, PCell, etc., as described above with reference to FIGs. 1-3. Additionally, SN 410 may be an example of a base station 105, SN, SCG, SCell, PSCell, etc., as described above with reference to FIGs. 1-3. Process flow 400 may include signaling between UE 115-c, last serving MN 405, and SN 410 for an initial cell setup according to a DC configuration when UE 115-c is initially in an idle communication state as described above with reference to FIG. 2. In some cases, last serving MN 405 may operate in a first RAT, and SN 410 may operate in a second RAT, which may be different or the same as the first RAT, indicating a MR-DC configuration for communications between UE 115-c, last serving MN 405, and SN 410.

At 412, UE 115-c may transition from the idle communication state to a connected communication state and initiate a RACH procedure with last serving MN 405. For example, UE 115-c may transmit a Msg1 of the RACH procedure that include a PRACH preamble as described above. In some cases, last serving MN 405 may represent a MN that UE 115-c had been connected to prior to entering the idle communication state. Assuming UE 115-c has not moved a large distance between entering the idle communication state and now exiting the idle communication state to enter the connected communication state, UE 115-c and last serving MN 405 may include contexts of each other in order to continue communications. In some cases, Msg1 of the RACH procedure may include a latency of three (3) TTIs, which includes two (2) TTIs as a worst case delay due to a RACH scheduling period and one (1) TTI for the transmission of the PRACH preamble.

At 414, last serving MN 405 may transmit a Msg2 of the RACH procedure that includes the RAR to the Msg1. In some cases, Msg2 of the RACH procedure may also include a latency of three (3) TTIs, which includes one (1) TTI for a preamble detection at last serving MN 405, one (1) TTI for downlink slot alignment, and one (1) TTI for the RAR transmission. At 416, UE 115-c may transmit a Msg3 of the RACH procedure to request an RRC setup with last serving MN 405. In some cases, Msg3 of the RACH procedure may also include a latency of three (3) TTIs, which includes one (1) TTI for processing Msg2 at UE 115-c, one (1) TTI for uplink slot alignment, and one (1) TTI for the Msg3 transmission.

At 418, last serving MN 405 may transmit a Msg4 of the RACH procedure to setup the RRC connection with UE 115-c. In some cases, Msg4 of the RACH procedure may include a latency of three (3) ms and two (2) TTIs, which includes the three (3) ms for layer 2 (L2) /RRC processing at last serving MN 405, one (1) TTI for downlink slot alignment, and one (1) TTI for the Msg4 transmission. At 420, UE 115-c may transmit a Msg5 of the RACH procedure to indicate the RRC setup is complete with last serving MN 405. In some cases, Msg5 of the RACH procedure may include a latency of 10 ms and two (2) TTIs, which includes 10 ms for L2/RRC processing at UE 115-c, one (1) TTI for uplink slot alignment, and one (1) TTI for the Msg5 transmission.

At 422 and 424, last serving MN 405 and UE 115-c may establish an RRC security mode through an RRC SMC message and an RRC security mode complete message. The RRC SMC and RRC security mode complete messages may include a latency of eight (8) ms and four (4) TTIs, which includes five (5) ms for RRC processing at UE 115-c, three (3) ms for RRC processing at last serving MN 405, one (1) TTI for downlink slot alignment at last serving MN 405, one (1) TTI for transmitting the RRC SMC message, one (1) TTI for uplink slot alignment at UE 115-c, and one (1) TTI for transmitting the RRC security mode complete message.

At 426 and 428, last serving MN 405 and UE 115-c may reconfigure the RRC connection to include SN 410 for a DC configuration through an RRC reconfiguration message and an RRC reconfiguration complete message. In some cases, the RRC reconfiguration message and the RRC reconfiguration complete message may include a latency of 13 ms and two (2) TTIs, which includes 10 ms for RRC processing at UE 115-c, three (3) ms for RRC processing at last serving MN 405, one (1) TTI for downlink slot alignment at last serving MN 405, one (1) TTI for transmitting the RRC SMC message, and over-the-air (OTA) latency to send the RRC reconfiguration complete message is ignored. Additionally, in the RRC reconfiguration message, last serving MN 405 may transmit a measurement configuration for UE 115 to perform measurements on one or more cells of a SCG to establish communications with SN 410 according to the DC configuration. Accordingly, at 430, UE 115-c may perform Layer 3 (L3) measurements on the one or more cells of the SCG.

At 432, UE 115-c may transmit L3 measurement reports based on the measurements performed on the one or more cells of the SCG at 430. UE 115-c may transmit these L3 measurement reports periodically or based on an event trigger. In some cases, the L3 measurement reports may include a latency of greater than or equal to 120 ms based on 120 ms being a shortest measurement duration from a log in UE 115-c.

At 434 and 436, last serving MN 405 and SN 410 may perform a SN addition establishment based on an SN addition request message and an SN addition request acknowledgement (ACK) message. In some cases, the SN addition request message and the SN addition request ACK message may include a latency of 10 ms, which includes an assumption of a five (5) ms latency for backhaul signaling of the SN addition request message and a five (5) ms latency for backhaul signaling of the SN addition request ACK message.

At 438 and 440, last serving MN 405 and UE 115-c may establish the SCG connection for UE 115-c based on an additional RRC reconfiguration message and an additional RRC reconfiguration complete message. For example, the additional RRC reconfiguration message may carry an RRC configuration for SN 410 based on the SN addition establishment performed at 434 and 436. In some cases, the additional RRC reconfiguration message and the additional RRC reconfiguration complete message may include a latency of 19 ms and four (4) TTIs, which includes 16 ms for RRC processing at UE 115-c, three (3) ms for RRC processing at last serving MN 405, one (1) TTI for downlink slot alignment at last serving MN 405, one (1) TTI for transmitting the additional RRC reconfiguration message, one (1) TTI for uplink slot alignment at UE 115-c, and one (1) TTI for transmitting the additional RRC reconfiguration complete message.

At 442, last serving MN 405 may transmit an SN reconfiguration complete message to SN 410 based on the SCG connection established at 438 and 440. In some cases, the SN reconfiguration complete message may include a latency of five (5) ms for backhaul signaling of the SN reconfiguration complete message.

At 444, UE 115-c and SN 410 may perform a RACH procedure (e.g., random access procedure) to establish a connection for completing the DC configuration. In some cases, this RACH procedure may include a latency of three (3) ms and 11 TTIs based on a contention-based random access (CBRA) procedure assuming worst case delays.

At 446, if the RACH procedure is successful with SN 410, UE 115-c and SN 410 may transmit data between each other. In total, the initial cell setup as shown in process flow 400 for establishing a DC configuration between UE 115-c, last serving MN 405, SN 410 may include a latency of 201 ms and 36 TTIs. Based on the subcarrier spacing (SCS) used, the latency may be greater (e.g., 237 ms for a 15 kHz SCS) . As can be seen, the measurement reporting for the one or more cells of the SCG to identify and connect with SN 410 takes up a majority of the latency for the initial cell setup (e.g., at least 120 ms of the total 201 ms) . Accordingly, as described herein, the use of a blind SCG configuration may reduce the latency, in part, by eliminating the L3 measurement reporting as described in process flow 400.

FIG. 5 illustrates an example of a process flow 500 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, process flow 500 may implement aspects of wireless communications systems 100 and/or 200. Process flow 500 may include a UE 115-d, a last serving MN 505, and an SN 510. UE 115-d may be an example of a UE 115 as described above with reference to FIGs. 1-4. Last serving MN 505 may be an example of a base station 105, MN, MCG, PCell, etc., as described above with reference to FIGs. 1-4. Additionally, SN 510 may be an example of a base station 105, SN, SCG, SCell, PSCell, etc., as described above with reference to FIGs. 1-4. Process flow 500 may include signaling between UE 115-d, last serving MN 505, and SN 510 for an initial cell setup according to a DC configuration when UE 115-d is initially in an inactive communication state as described above with respect to FIG. 2. In some cases, last serving MN 505 may operate in a first RAT, and SN 510 may operate in a second RAT, which may be different or the same as the first RAT, indicating a MR-DC configuration for communications between UE 115-d, last serving MN 505, and SN 510.

Process flow 500 may include a number of the same messages transmitted between UE 115-d and last serving MN 505 as the messages transmitted between UE 115-c and last serving MN 405 as described above with reference to process flow 400 of FIG. 4. For example, at 515, 520, 525, 530, 535, UE 115-d and last serving MN 505 may perform a RACH procedure, including the respective RACH messages (e.g., Msg1, Msg2, Msg3, Msg4, Msg5) as described above with reference to 412, 414, 416, 418, and 420. However, based on UE 115-d initially being in the inactive communication state rather than the idle communication state that UE 115-c initially was in, the RRC setup messages described in process flow 400 may be RRC resume messages based on UE 115-d and last serving MN 405 storing higher-layer configurations. Additionally, compared with being in the idle communication state, UE 115-d and last serving MN 505 may have no need to perform the SMC messaging based on the stored higher-layer configurations.

The rest of process flow 500 may correspond to the same types of messages transmitted as described with reference to process flow 400. For example, the RRC reconfiguration (e.g., 540 and 545) , the L3 measurement reporting (e.g., 550 and 555) , the SN addition establishment (e.g., 560 and 565) , the SCG connection establishment (e.g., 570 and 575) , the SN reconfiguration complete message (e.g., 580) , the RACH procedure with SN 510 (e.g., 585) , and transmitting data based on the RACH (e.g., 590) may correspond to the same messages as shown and described in process flow 400.

Based on not needing to transmit the SMC messages, the latency of the initial cell setup may be reduced (e.g., the latency of the two (2) SMC messages as described in process flow 400 are saved) . For example, the total latency of the initial cell setup when UE 115-d is in the inactive communication state may be 183 ms (or 213 ms for a SCS of 15 kHz) and 40 TTIs. Additionally, UE 115-d may start its L3 measurements earlier (e.g., right after transmitting Msg5 of the RACH procedure with last serving MN 405) when it receives the RRC reconfiguration message that includes the measurement configuration for the one or more cells of the SCG. As such, the DC configuration for communicating with both last serving MN 505 and SN 510 may be established faster with respect to setup described with reference to process flow 400. However, UE 115-d may still wait for security (e.g., AS security) to be established before performing the L3 measurements.

Additionally, the additional RRC reconfiguration messages transmitted at 570 and 575 may be saved if a lower-layer configuration of a last serving SN (e.g., SN 510) was enabled to be stored at UE 115-d and/or last serving MN 505. Accordingly, the latency may be reduced further based on not transmitting the additional RRC reconfiguration messages. As described herein, the use of blind SCG configurations may allow for UE 115-d and/or last serving MN 505 to store a previously used SCG configuration and determine whether the stored SCG configuration can be used for the DC configuration.

FIG. 6 illustrates an example of a process flow 600 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, process flow 600 may implement aspects of wireless communications systems 100 and/or 200. Process flow 600 may include a UE 115-e, a last serving MN 605, and an SN 610. UE 115-e may be an example of a UE 115 as described above with reference to FIGs. 1-5. Last serving MN 605 may be an example of a base station 105, MN, MCG, PCell, etc., as described above with reference to FIGs. 1-5. Additionally, SN 610 may be an example of a base station 105, SN, SCG, SCell, PSCell, etc., as described above with reference to FIGs. 1-5. In some cases, last serving MN 605 may operate in a first RAT, and SN 610 may operate in a second RAT, which may be different or the same as the first RAT, indicating a MR-DC configuration for communications between UE 115-e, last serving MN 605, and SN 610.

Process flow 600 may include signaling between UE 115-e, last serving MN 605, and SN 610 for an early measurement reporting scheme when UE 115-e is initially in an inactive communication state as described above with respect to FIG. 2. Based on being in the inactive communication state, surety (e.g., AS security) may be activated between UE 115-e and last serving MN 605 upon UE 115-e receiving a resume communications message (e.g., RRC resume communications message) , which may enable earlier measurements of cells in an SCG for resuming communications with a SN (e.g., SN 610) .

At 615, last serving MN 605 may transmit an RRC release message (e.g., similar to the RRC release message as described with reference to process flow 300) , where UE 115-e may obtain a measurement configuration of potential SCell frequencies in the RRC release message. Additionally, based on receiving the RRC release message, UE 115-e may enter the inactive communication state, dropping any lower-layer SCG configurations for SN 610. However, the measurement configuration of potential SCell frequencies may enable UE 115-e to perform L3 measurements of the different SCell frequencies while in the inactive communication state after receiving the RRC release message.

At 620, UE 115-e may transition from the inactive communication state to a connected communication state. As such, UE 115-e may initiate a RACH procedure with its last serving MN 605 through a Msg1 of the RACH procedure, including a PRACH preamble. Subsequently, at 625, last serving MN 605 may transmit a Msg2 of the RACH procedure, including a RAR.

At 630, when transmitting a Msg3 of the RACH procedure to request to resume an RRC connection with last serving MN 605, UE 115-e may also indicate an availability of early measurement based on the L3 measurements performed for the different SCell frequencies while in the inactive communication state. For example, UE 115-e may include a one (1) bit indication in the Msg3 for the availability of early measurements.

At 635, when transmitting a Msg4 of the RACH procedure to resume the RRC connection with UE 115-e, last serving MN 605 may include a request for the measurement reporting based on receiving the indication for the availability of early measurements in the Msg3.

Accordingly, at 640, when transmitting a Msg5 of the RACH procedure to complete resuming of the RRC connection with last serving MN 605, UE 115-e may report the L3 measurement results based on receiving the request in the Msg4. Based on this early reporting, UE 115-e and last serving MN 605 may skip the RRC reconfiguration messaging as described above with reference to process flows 400 and 500, thereby further reducing the latency of establishing the DC configuration between UE 115-e, last serving MN 605, and SN 610.

However, a lower-layer SCG configuration for SN 610 may still need to be established and determined. Accordingly, the messages transmitted at 645, 650, 655, 660, and 665 may correspond to similar messages as described above with reference to process flows 400 and 500. For example, last serving MN 605 and SN 610 may perform the SN additional establishment (e.g., 645 and 650) and then may perform the SCG connection establishment with the SN reconfiguration complete message (e.g., 655, 660, and 665) . Based on last serving MN 605 determining the lower-layer SCG configuration through the SN additional establishment and then signaling the determined lower-layer SCG configuration to UE 115-e in the SCG connection establishment, UE 115-e may then initiate a RACH procedure with SN 610 using the lower-layer SCG configuration at 670. Accordingly, if the RACH procedure is successful, at 675, UE 115-e may resume its connection with SN 610 and begin transmitting data back and forth.

As described herein, the use of blind SCG configurations may allow for UE 115-e and/or last serving MN 605 to store a previously used SCG configuration and determine whether the stored SCG configuration can be used for the DC configuration, thereby further reducing the latency and amount of signaling to determine a lower-layer SCG configuration for SN 610.

FIG. 7 illustrates an example of a process flow 700 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, process flow 700 may implement aspects of wireless communications systems 100 and/or 200. Process flow 700 may include a UE 115-f, a last serving MN 705, and an SN 710. UE 115-f may be an example of a UE 115 as described above with reference to FIGs. 1-6. Last serving MN 705 may be an example of a base station 105, MN, MCG, PCell, etc., as described above with reference to FIGs. 1-6. Additionally, SN 710 may be an example of a base station 105, SN, SCG, SCell, PSCell, etc., as described above with reference to FIGs. 1-6. UE 115-f may be operating in a DC configuration with last serving MN 705 and SN 710. In some cases, last serving MN 705 may operate in a first RAT, and SN 710 may operate in a second RAT, which may be different or the same as the first RAT, indicating a MR-DC configuration for communications between UE 115-f, last serving MN 705, and SN 710.

At 715, UE 115-f may receive, from last serving MN 705, a release message (e.g., an RRC release message as described above with reference to process flows 300 and 600) instructing UE 115-f to enter an inactive communications state with SN 710. For example, the release message may include a configuration for UE 115-f to suspend communications with a SCG that includes SN 710 (e.g., a suspendConfig message) . Additionally, UE 115-f may receive an indication that it is to store a lower-layer SCG configuration. In some cases, this stored lower-layer SCG configuration may be a previously used lower-layer SCG configuration for communicating with SN 710 prior to receiving the release message and suspending the SN communications. Additionally or alternatively, the lower-layer SCg configuration may include at least one of an identifier for SN 710 of the DC configuration, parameters for SN communications, or configuration information for one or more cells of a SCG. This indication to store the lower-layer SCG configuration may be included with an IE on the release message (e.g., an indication-store-SCGconfiguration IE) .

In some cases, additional IEs may be added to the release message to enable UE 115-f to determine whether its previously stored lower-layer SCG configuration can be used if UE 115-f attempts to resume the SN communications (e.g., resume SCG communications) . For example, UE 115-f may identify, from information included with the release message (e.g., the additional IEs) , a validity area (e.g., a validity-area IE) which defines one or more cells in which the previously stored lower-layer SCG configuration may be valid for use and determine whether it is within the one or more cells defined by the validity area. Accordingly, if UE 115-f reselects a cell outside of this validity area list of one or more cells, it may determine that the previously stored lower-layer SCG configuration is no longer valid. In some cases, the validity area may include a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a RAN notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.

Additionally, UE 115-f may identify, from information included with the release message (e.g., the additional IEs) , a validity time (e.g., a validity-timer IE) which defines a period in which the previously stored lower-layer SCG configuration is valid and determine whether the previously stored lower-layer SCG configuration is valid based on the validity time. For example, when the time expires, UE 115-f may regard the previously stored SCG configuration as outdated and discard it. Accordingly, the validity time may start when UE 115-f receives the release message and stops if UE 115-f transmits a request to resume communications with last serving MN 705. Additionally, last serving MN 705 may start a validity timer after transmitting the release message and may discard a stored lower-layer SCG configuration at itself (i.e., the last serving MN 705) when the timer expires. The validity timer for last serving MN 705 may stop upon reception of a Msg3 (e.g., request to resume an RRC connection) from UE 115-f as part of a RACH procedure.

In some cases, UE 115-f may identify, from information included with the release message (e.g., the additional IEs) , a threshold measurement value (e.g., threshold IE) . Based on this threshold measurement value, UE 115-f may measure signal reception conditions for comparison with the threshold measurement value and determine whether the previously stored lower-layer SCG configuration is valid based on the measurements satisfying the threshold measurement value. For example, after receiving a Msg2 of a RACH procedure, UE 115-f may compare a quality of a PSCell included in the previously stored SCG configuration with the configured threshold measurement value. If the quality of the PSCell is lower than the threshold, then UE 115-f regards the previously stored SCG configuration outdated and discards it. In some cases, the threshold measurement value may include a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof. Additional examples of IEs that may enable UE 115-f to determine whether its previously stored lower-layer secondary cell group configuration can be used for the resumption of SN communications may be defined and included in the release message that are not described above.

At 720, UE 115-f may store the lower-layer SCG configuration based on receiving the indication to store the lower-layer SCG configuration with the release message. Additionally, UE 115-f may store a higher-layer SCG configuration based on receiving the release message. For example, as described above with reference to FIG. 2, when transitioning to an inactive communication state, UE 115-f and last serving MN 705 may store higher-layer SCG configurations.

At 725, UE 115-f may transition to a connected communication state as described above with reference to FIG. 2. Accordingly, UE 115-f may initiate a RACH procedure to resume communications with its last serving MN 705. For example, UE 115-f may transmit a Msg1 of the RACH procedure that includes a PRACH preamble. In some cases, UE 115-f may initiate the RACH procedure based on determining that SN communication are to resume. At 730, last serving MN 705 may transmit a Msg2 of the RACH procedure including a RAR based on the Msg1.

At 735, UE 115-f may determine whether the previously stored lower-layer SCG configuration can be used for the resumption of SN communications with SN 710 based on the additional IEs as described above (e.g., validity area, validity timer, threshold measurement value, etc. ) . For example, UE 115-f may check that the validity area and validity time are matched in a cell for resuming the SN communications (e.g., SN 710) and that the quality of a corresponding PSCell included in the previously stored lower-layer SCG configuration is higher than the configured threshold. Accordingly, UE 115-f may discard the previously stored lower-layer SCG configuration based on determining the SCG configuration not being valid.

At 740, UE 115-f may transmit a Msg3 of the RACH procedure to request to resume a connection with last serving MN 705 (e.g., an RRCResumeRequest message) . Additionally, based on if the previously stored SCG configuration is validated, UE 115-f may include an indication with the Msg3 that the previously stored SCG configuration can be resumed. Accordingly, at 745, UE 115-f may apply the previously stored SCG configuration based on it being validated at 735.

At 750, last serving MN 705 may transmit, to SN 710 of the DC configuration, an activation request message for the SN communications based on receiving the message from the UE that the secondary node communications are to resume (e.g., Msg3) . At 755, last serving 705 may transmit, to UE 115-f, a resume communications message (e.g., Msg4 of the RACH procedure or RRCResume message) for the SN communications based on receiving the indication from UE 115-f whether the stored lower-layer SCG configuration is to be used for the SN communications. In some cases, 750 and 755 may happen at the same time, where last serving MN 705 transmits the resume communications message and the activation request message simultaneously based on last serving MN 705 storing a context for SN 710 (e.g., including a lower-layer SCG configuration that can be used for SN 710) . Additionally, at 760, SN 710 may transmit an SN addition request ACK message based on receiving the activation request message, where the SN addition request ACK message confirms that UE 115-f can initiate communications with SN 710 for the DC configuration.

At 765, UE 115-f may transmit a Msg5 of the RACH procedure to complete the resuming of communications with last serving MN 705 (e.g., RRCResumeComplete message) . At 770, after transmitting the Msg5, UE 115-f may perform an additional RACH procedure with a PSCell of SN 710. Subsequently, at 775, upon the additional RACH procedure being successful at the PSCell, UE 115-f may resume connections with both last serving MN 705 and SN 710. In some cases, UE 115-f may apply or replace one or more parameters for the previously stored lower-layer SCG configuration based on information broadcasted in SIBs from SN 810 after resuming its connection with SN 810. Accordingly, at 780, UE 115-f may transmit data back and forth with SN 710 based on resuming the connections.

FIG. 8 illustrates an example of a process flow 800 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, process flow 800 may implement aspects of wireless communications systems 100 and/or 200. Process flow 800 may include a UE 115-g, a last serving MN 805, and an SN 810. UE 115-g may be an example of a UE 115 as described above with reference to FIGs. 1-7. Last serving MN 805 may be an example of a base station 105, MN, MCG, PCell, etc., as described above with reference to FIGs. 1-7. Additionally, SN 810 may be an example of a base station 105, SN, SCG, SCell, PSCell, etc., as described above with reference to FIGs. 1-7. UE 115-g may be operating in a DC configuration with last serving MN 805 and SN 810. In some cases, last serving MN 805 may operate in a first RAT, and SN 810 may operate in a second RAT, which may be different or the same as the first RAT, indicating a MR-DC configuration for communications between UE 115-g, last serving MN 805, and SN 810.

Process flow 800 may include similar messages as described and transmitted in process flow 700. However, in some cases, UE 115-g may be unable to store a previously used lower-layer SCG configuration (e.g., due to memory limitations) . However, last serving MN 805 may still store a lower-layer SCG configuration for SN 810.

Accordingly, at 815, when transmitting a release message to suspend communications between UE 115-g and SN 810 (e.g., for UE 115-g to enter an inactive communication state) , last serving MN 805 may also include a measurement configuration for a SCG including SN 810 of the DC configuration. Additionally, the additional IEs for determining whether a SCG configuration is valid may also be transmitted with the release message (e.g., the validity area, validity time, and threshold measurement value) . In some cases, last serving MN 805 may still transmit an IE for storing the lower-layer SCG configuration, but may set it to false.

As such, at 820, UE 115-g may enter the inactive communication state and store the higher-layer SCG configuration but may refrain from storing any lower-layer SCG configuration. At 825 and 830, UE 115-g and last serving MN 805 may transmit similar RACH messages as described above with reference to process flow 700.

At 835, UE 115-g may determine whether one or more cells in the SCG can be used for resumption of the SN communication based on the measurement configuration. For example, UE 115-g may perform measurements in accordance with the measurement configuration and determine whether to include an indication that a previously stored lower-layer secondary cell group configuration is available for resuming the SN communications based on the measurements. In some cases, UE 115-g may perform measurements on cells that are included in the validity area, and if UE 115-g reselects to a cell or RNA outside a list of cells indicated by the validity area, measurements may no loner be required for that cell/RNA. Additionally or alternatively, if the validity time expires, UE 115-g may regard the measurement configuration for the SCG to not be valid and may stop performing the measurements. In some cases, UE 115-g may also stop performing the measurements for a particular SCell if a cell quality for that SCell falls below the threshold measurement value.

At 840, when transmitting a Msg3 of the RACH procedure, UE 115-g may also transmit assistance information to last serving MN 805 based on the measurements performed at 835. For example, the assistance information may include information to assist last serving MN 805 in determining whether to apply the previously stored lower-layer SCG configuration at the last serving MN 805 or an updated lower-layer SCG configuration. In some cases, UE 115-g may include a suggested PSCell identifier with the assistance information.

At 845 and 850, last serving MN 805 and SN 810 may confirm that SN 810 is added to the DC configuration based on an SN addition request message and an SN addition request ACK message similar to the messages as described above with reference to process flows 400, 500, 600, and 700.

At 855, when transmitting a Msg4 of the RACH procedure, last serving MN 805 may transmit a lower-layer SCG configuration based on the assistance information received in the Msg3 of the RACH procedure. This lower-layer SCG configuration may enable UE 115-g to resume a connection with SN 810 according to the DC configuration.

At 860, 865, 870, and 875, UE 115-f may perform similar steps as described in process flow 700 to complete a resuming of a connection with last serving MN 805 (e.g., 860) , perform an additional RACH with SN 810 (e.g., 865) , resume connections with both last serving MN 805 and SN 810 (e.g., 870) , and transmitting data back and forth with SN 810 based on resuming the connections (e.g., 875) .

FIG. 9 illustrates an example of a process flow 900 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. In some examples, process flow 900 may implement aspects of wireless communications systems 100 and/or 200. Process flow 900 may include a UE 115-h, a last serving MN 905, and an SN 910. UE 115-h may be an example of a UE 115 as described above with reference to FIGs. 1-8. Last serving MN 905 may be an example of a base station 105, MN, MCG, PCell, etc., as described above with reference to FIGs. 1-8. Additionally, SN 910 may be an example of a base station 105, SN, SCG, SCell, PSCell, etc., as described above with reference to FIGs. 1-8. UE 115-h may be operating in a DC configuration with last serving MN 905 and SN 910. In some cases, last serving MN 905 may operate in a first RAT, and SN 910 may operate in a second RAT, which may be different or the same as the first RAT, indicating a MR-DC configuration for communications between UE 115-h, last serving MN 905, and SN 910.

Process flow 900 may include similar messages and measurement configurations as described above with reference to process flow 800. For example, 915, 920, 925, 930, 935, 940, 945, 950, 955, 965, 975, 980, and 985 may correspond to similar messages and processes as described above with reference to process flow 800. However, rather than transmitting a lower-layer SCG configuration in a Msg4 of a RACH procedure, last serving MN 905 may transmit, at 960, the lower-layer SCG configuration based on the measurement configuration in a reconfiguration message (e.g., RRCReconfiguration message) following the Msg4 transmission at 955. Accordingly, UE 115-h may also transmit a reconfiguration complete message at 970 based on receiving the reconfiguration message.

FIG. 10 shows a block diagram 1000 of a device 1005 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The device 1005 may be an example of aspects of a UE 115 as described herein. The device 1005 may include a receiver 1010, a UE communications 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 blind SCG configuration in MR-DC, 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 UE communications manager 1015 may identify that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN. In some cases, the UE communications manager 1015 may determine that SN communications are to resume. Additionally, the UE communications manager 1015 may determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications. In some cases, the UE communications manager 1015 may transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications. The UE communications manager 1015 may be an example of aspects of the UE communications manager 1310 described herein.

The UE communications 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 UE communications manager 1015, or its sub-components may be executed by a general-purpose processor, a digital signal processor (DSP) , an application-specific integrated circuit (ASIC) , a field-programmable gate array (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 communications 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 UE communications 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 UE communications 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 blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The device 1105 may be an example of aspects of a device 1005, or a UE 115 as described herein. The device 1105 may include a receiver 1110, a UE communications manager 1115, and a transmitter 1140. 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 blind SCG configuration in MR-DC, 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 UE communications manager 1115 may be an example of aspects of the UE communications manager 1015 as described herein. The UE communications manager 1115 may include an inactive state component 1120, a resume communications component 1125, a lower-layer SCG configuration component 1130, and a lower-layer SCG configuration indicator 1135. The UE communications manager 1115 may be an example of aspects of the UE communications manager 1310 described herein.

The inactive state component 1120 may identify that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN.

The resume communications component 1125 may determine that SN communications are to resume.

The lower-layer SCG configuration component 1130 may determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications.

The lower-layer SCG configuration indicator 1135 may transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications.

The transmitter 1140 may transmit signals generated by other components of the device 1105. In some examples, the transmitter 1140 may be collocated with a receiver 1110 in a transceiver module. For example, the transmitter 1140 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The transmitter 1140 may utilize a single antenna or a set of antennas.

FIG. 12 shows a block diagram 1200 of a UE communications manager 1205 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The UE communications manager 1205 may be an example of aspects of a UE communications manager 1015, a UE communications manager 1115, or a UE communications manager 1310 described herein. The UE communications manager 1205 may include an inactive state component 1210, a resume communications component 1215, a lower-layer SCG configuration component 1220, a lower-layer SCG configuration indicator 1225, a lower-layer SCG configuration storage component 1230, a validity area component 1235, a validity timer component 1240, a threshold component 1245, a SCG measurement component 1250, and a lower-layer SCG configuration receiver 1255. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The inactive state component 1210 may identify that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN. In some cases, the MN may operate in a first RAT, and the SN may operate in a second RAT.

The resume communications component 1215 may determine that SN communications are to resume.

The lower-layer SCG configuration component 1220 may determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications. In some examples, the lower-layer SCG configuration component 1220 may discard the previously stored lower-layer SCG configuration based on determining that the SCG configuration not being valid. In some cases, the lower-layer SCG configuration may include at least one of an identifier for the SN of the DC configuration, parameters for the SN communications, or configuration information for one or more cells of the SCG.

The lower-layer SCG configuration indicator 1225 may transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications.

The lower-layer SCG configuration storage component 1230 may receive, with a release message instructing the UE to enter the inactive communications state, an indication that the UE is to store a lower-layer SCG configuration. Accordingly, in some examples, the lower-layer SCG configuration storage component 1230 may store the lower-layer SCG configuration such that the lower-layer SCG configuration becomes the previously stored lower-layer SCG configuration. Additionally or alternatively, the lower-layer SCG configuration storage component 1230 may store a higher-layer SCG configuration based on receiving a release message.

The validity area component 1235 may identify, from information included with the release message, a validity area which defines one or more cells in which the previously stored lower-layer SCG configuration is valid for use. In some examples, the validity area component 1235 may determine whether the UE is within the one or more cells defined by the validity area. In some cases, the validity area may include a list of the one or more cells, a PCI list of the one or more cells, an RNA list of the one or more cells, a TA list of the one or more cells, or a combination thereof.

The validity timer component 1240 may identify, from information included with the release message, a validity time which defines a period in which the previously stored lower-layer SCG configuration is valid. In some examples, the validity timer component 1240 may determine whether the previously stored lower-layer SCG configuration is valid based on the validity time.

The threshold component 1245 may identify, from information included with the release message, a threshold measurement value. In some examples, the threshold component 1245 may measure signal reception conditions for comparison with the threshold measurement value and may determine whether the previously stored lower-layer SCG configuration is valid based on the UE measurements satisfying the threshold measurement value. In some cases, the threshold measurement value may include an RSRP measurement, an RSRQ measurement, or a combination thereof.

The SCG measurement component 1250 may receive, with a release message instructing the UE to enter the inactive communications state, a measurement configuration for a SCG including the SN of the DC configuration. In some examples, the SCG measurement component 1250 may perform measurements in accordance with the measurement configuration and may determine whether to include the indication that the previously stored lower-layer SCG configuration is available for resuming the SN communications based on the measurements. Additionally, in some examples, the SCG measurement component 1250 may transmit, to the MN and in addition to transmission of the indication, assistance information based on the measurements made in accordance with the measurement configuration, where the assistance information includes information to assist the MN in determining whether to apply the previously stored lower-layer SCG configuration or the updated lower-layer SCG configuration.

The lower-layer SCG configuration receiver 1255 may receive, from the MN and in response to the indication, a lower-layer SCell configuration to be used by the UE for SN communications, where the lower-layer SCell configuration is either the previously stored lower-layer SCG configuration, as stored by the MN, or an updated lower-layer SCG configuration. In some examples, the lower-layer SCG configuration receiver 1255 may receive the lower-layer SCell configuration in a resume communications message or a reconfiguration message.

FIG. 13 shows a diagram of a system 1300 including a device 1305 that supports blind SCG configuration in MR-DC 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 UE 115 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 UE communications manager 1310, an I/O controller 1315, a transceiver 1320, an antenna 1325, memory 1330, and a processor 1340. These components may be in electronic communication via one or more buses (e.g., bus 1345) .

The UE communications manager 1310 may identify that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN. In some cases, the UE communications manager 1310 may determine that SN communications are to resume. Additionally, the UE communications manager 1310 may determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications. In some cases, the UE communications manager 1310 may transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications.

The I/O controller 1315 may manage input and output signals for the device 1305. The I/O controller 1315 may also manage peripherals not integrated into the device 1305. In some cases, the I/O controller 1315 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 1315 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 1315 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 1315 may be implemented as part of a processor. In some cases, a user may interact with the device 1305 via the I/O controller 1315 or via hardware components controlled by the I/O controller 1315.

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 random-access memory (RAM) and read-only memory (ROM) . The memory 1330 may store computer-readable, computer-executable code 1335 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 1330 may contain, among other things, a basic I/O system (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 central processing unit (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 other cases, a memory controller may be integrated into the 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 blind SCG configuration in MR-DC) .

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 block diagram 1400 of a device 1405 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The device 1405 may be an example of aspects of a base station 105 as described herein. The device 1405 may include a receiver 1410, a base station communications manager 1415, and a transmitter 1420. The device 1405 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 1410 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 blind SCG configuration in MR-DC, etc. ) . Information may be passed on to other components of the device 1405. The receiver 1410 may be an example of aspects of the transceiver 1720 described with reference to FIG. 17. The receiver 1410 may utilize a single antenna or a set of antennas.

The base station communications manager 1415 may identify that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE. In some cases, the base station communications manager 1415 may transmit, to the UE, a release message indicating a suspension of SN communications for the UE. Additionally, the base station communications manager 1415 may store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE. In some cases, the base station communications manager 1415 may receive a message from the UE that the SN communications are to resume. Additionally, the base station communications manager 1415 may receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications. The base station communications manager 1415 may be an example of aspects of the base station communications manager 1710 described herein.

The base station communications manager 1415, 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 communications manager 1415, or its sub-components may be executed by 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 in the present disclosure.

The base station communications manager 1415, 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 communications manager 1415, 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 communications manager 1415, or its sub-components, may be combined with one or more other hardware components, including but not limited to an 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 1420 may transmit signals generated by other components of the device 1405. In some examples, the transmitter 1420 may be collocated with a receiver 1410 in a transceiver module. For example, the transmitter 1420 may be an example of aspects of the transceiver 1720 described with reference to FIG. 17. The transmitter 1420 may utilize a single antenna or a set of antennas.

FIG. 15 shows a block diagram 1500 of a device 1505 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The device 1505 may be an example of aspects of a device 1405, or a base station 105 as described herein. The device 1505 may include a receiver 1510, a base station communications manager 1515, and a transmitter 1545. The device 1505 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 1510 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 blind SCG configuration in MR-DC, etc. ) . Information may be passed on to other components of the device 1505. The receiver 1510 may be an example of aspects of the transceiver 1720 described with reference to FIG. 17. The receiver 1510 may utilize a single antenna or a set of antennas.

The base station communications manager 1515 may be an example of aspects of the base station communications manager 1415 as described herein. The base station communications manager 1515 may include a DC configuration component 1520, a release message transmitter 1525, a MN lower-layer SCG configuration storage component 1530, a resume SN communications component 1535, and a lower-layer SCG configuration indication receiver 1540. The base station communications manager 1515 may be an example of aspects of the base station communications manager 1710 described herein.

The DC configuration component 1520 may identify that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE.

The release message transmitter 1525 may transmit, to the UE, a release message indicating a suspension of SN communications for the UE.

The MN lower-layer SCG configuration storage component 1530 may store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE.

The resume SN communications component 1535 may receive a message from the UE that the SN communications are to resume.

The lower-layer SCG configuration indication receiver 1540 may receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications.

The transmitter 1545 may transmit signals generated by other components of the device 1505. In some examples, the transmitter 1545 may be collocated with a receiver 1510 in a transceiver module. For example, the transmitter 1545 may be an example of aspects of the transceiver 1720 described with reference to FIG. 17. The transmitter 1545 may utilize a single antenna or a set of antennas.

FIG. 16 shows a block diagram 1600 of a base station communications manager 1605 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The base station communications manager 1605 may be an example of aspects of a base station communications manager 1415, a base station communications manager 1515, or a base station communications manager 1710 described herein. The base station communications manager 1605 may include a DC configuration component 1610, a release message transmitter 1615, a MN lower-layer SCG configuration storage component 1620, a resume SN communications component 1625, a lower-layer SCG configuration indication receiver 1630, a lower-layer SCG configuration storage indicator 1635, a validity area indication transmitter 1640, a validity timer indication transmitter 1645, a threshold indication transmitter 1650, a SCG measurement configuration component 1655, a simultaneous transmission component 1660, and a MN validity timer component 1665. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The DC configuration component 1610 may identify that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE. In some cases, the MN may operate in a first RAT, and the SN may operate in a second RAT.

The release message transmitter 1615 may transmit, to the UE, a release message indicating a suspension of SN communications for the UE.

The MN lower-layer SCG configuration storage component 1620 may store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE. In some examples, the MN lower-layer SCG configuration storage component 1620 may discard the stored lower-layer SCG configuration based on receiving the indication from the UE that the stored SCG configuration is not to be used.

The resume SN communications component 1625 may receive a message from the UE that the SN communications are to resume.

The lower-layer SCG configuration indication receiver 1630 may receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications.

The lower-layer SCG configuration storage indicator 1635 may transmit, to the UE, an indication to store the lower-layer SCG configuration.

The validity area indication transmitter 1640 may transmit with the indication to store the lower-layer SCG configuration, information including a validity area which defines one or more cells in which the UE is to be located if the stored lower-layer SCG configuration is to be valid. In some cases, the validity area of the one or more cells in the SCG may include a list of the one or more cells, a PCI list of the one or more cells, an RNA list of the one or more cells, a TA list of the one or more cells, or a combination thereof.

The validity timer indication transmitter 1645 may transmit with the indication to store the lower-layer SCG configuration, information including a validity timer which defines a timing for when the stored lower-layer SCG configuration is valid.

The threshold indication transmitter 1650 may transmit with the indication to store the lower-layer SCG configuration, information including a threshold measurement value to allow the UE to determine whether the stored lower-layer SCG configuration is to be applied. In some cases, the threshold measurement value may include an RSRP measurement, an RSRQ measurement, or a combination thereof.

The SCG measurement configuration component 1655 may transmit, to the UE, a measurement configuration for a SCG including a SN of the DC configuration, where the indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications is received based on the measurement configuration. In some examples, the SCG measurement configuration component 1655 may receive, from the UE, assistance information based on transmitting the measurement configuration, where the assistance information includes an indication to apply the stored lower-layer SCG configuration for the UE to use for SN communications or an identifier of a primary secondary cell for the UE to use for the SN communications. Additionally or alternatively, the SCG measurement configuration component 1655 may transmit, to the UE, a lower-layer configuration for the SCG for the SN communications based on the assistance information. In some cases, the lower-layer configuration for the SCG may be transmitted in a resume communications message or a reconfiguration message.

The simultaneous transmission component 1660 may transmit, to a SN of the DC configuration, an activation request message for the SN communications based on receiving the message from the UE that the SN communications are to resume. Additionally, the simultaneous transmission component 1660 may transmit, to the UE, a resume communications message for the SN communications based on receiving the indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications, where the resume communications message and the activation request message are transmitted simultaneously.

The MN validity timer component 1665 may initiate a validity timer based on transmitting the release message. In some examples, the MN validity timer component 1665 may determine that the validity timer expires prior to receiving the message from the UE that the SN communications are to resume and may discard the stored lower-layer SCG configuration used for the SN communications by the UE based on the validity timer expiring.

FIG. 17 shows a diagram of a system 1700 including a device 1705 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The device 1705 may be an example of or include the components of device 1405, device 1505, or a base station 105 as described herein. The device 1705 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a base station communications manager 1710, a network communications manager 1715, a transceiver 1720, an antenna 1725, memory 1730, a processor 1740, and an inter-station communications manager 1745. These components may be in electronic communication via one or more buses (e.g., bus 1750) .

The base station communications manager 1710 may identify that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE. In some cases, the base station communications manager 1710 may transmit, to the UE, a release message indicating a suspension of SN communications for the UE. Additionally, the base station communications manager 1710 may store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE. In some cases, the base station communications manager 1710 may receive a message from the UE that the SN communications are to resume. Additionally, the base station communications manager 1710 may receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications.

The network communications manager 1715 may manage communications with the core network (e.g., via one or more wired backhaul links) . For example, the network communications manager 1715 may manage the transfer of data communications for client devices, such as one or more UEs 115.

The transceiver 1720 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 1720 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1720 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 1725. However, in some cases the device may have more than one antenna 1725, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 1730 may include RAM, ROM, or a combination thereof. The memory 1730 may store computer-readable code 1735 including instructions that, when executed by a processor (e.g., the processor 1740) cause the device to perform various functions described herein. In some cases, the memory 1730 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 1740 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 1740 may be configured to operate a memory array using a memory controller. In some cases, a memory controller may be integrated into processor 1740. The processor 1740 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1730) to cause the device 1705 to perform various functions (e.g., functions or tasks supporting blind SCG configuration in MR-DC) .

The inter-station communications manager 1745 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 1745 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 1745 may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations 105.

The code 1735 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code 1735 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 1735 may not be directly executable by the processor 1740 but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

FIG. 18 shows a flowchart illustrating a method 1800 that supports blind SCG configuration in MR-DC 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 communications manager as described with reference to FIGs. 10 through 13. 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 identify that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN. 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 an inactive state component as described with reference to FIGs. 10 through 13.

At 1810, the UE may determine that SN communications are to resume. 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 resume communications component as described with reference to FIGs. 10 through 13.

At 1815, the UE may determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications. 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 lower-layer SCG configuration component as described with reference to FIGs. 10 through 13.

At 1820, the UE may transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications. 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 lower-layer SCG configuration indicator as described with reference to FIGs. 10 through 13.

FIG. 19 shows a flowchart illustrating a method 1900 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The operations of method 1900 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1900 may be performed by a UE communications manager as described with reference to FIGs. 10 through 13. 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 1905, the UE may identify that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN. 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 an inactive state component as described with reference to FIGs. 10 through 13.

At 1910, the UE may receive, with a release message instructing the UE to enter the inactive communications state, an indication that the UE is to store a lower-layer SCG configuration. 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 lower-layer SCG configuration storage component as described with reference to FIGs. 10 through 13.

At 1915, the UE may store the lower-layer SCG configuration such that the lower-layer SCG configuration becomes the previously stored lower-layer SCG configuration. 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 lower-layer SCG configuration storage component as described with reference to FIGs. 10 through 13.

At 1920, the UE may determine that SN communications are to resume. 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 resume communications component as described with reference to FIGs. 10 through 13.

At 1925, the UE may determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications. The operations of 1925 may be performed according to the methods described herein. In some examples, aspects of the operations of 1925 may be performed by a lower-layer SCG configuration component as described with reference to FIGs. 10 through 13.

At 1930, the UE may transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications. The operations of 1930 may be performed according to the methods described herein. In some examples, aspects of the operations of 1930 may be performed by a lower-layer SCG configuration indicator as described with reference to FIGs. 10 through 13.

FIG. 20 shows a flowchart illustrating a method 2000 that supports blind SCG configuration in MR-DC in accordance with aspects of the present disclosure. The operations of method 2000 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 2000 may be performed by a UE communications manager as described with reference to FIGs. 10 through 13. 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 2005, the UE may identify that the UE is operating in a DC configuration with a MN and a SN, where the UE is in an inactive communications state with the SN. 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 an inactive state component as described with reference to FIGs. 10 through 13.

At 2010, the UE may receive, with a release message instructing the UE to enter the inactive communications state, a measurement configuration for a SCG including the SN of the DC configuration. 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 a SCG measurement component as described with reference to FIGs. 10 through 13.

At 2015, the UE may determine that SN communications are to resume. 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 resume communications component as described with reference to FIGs. 10 through 13.

At 2020, the UE may determine whether a previously stored lower-layer SCG configuration can be used for the resumption of SN communications. 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 lower-layer SCG configuration component as described with reference to FIGs. 10 through 13.

At 2025, the UE may transmit an indication to the MN indicating whether the previously stored lower-layer SCG configuration can be used to resume the SN communications. 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 lower-layer SCG configuration indicator as described with reference to FIGs. 10 through 13.

FIG. 21 shows a flowchart illustrating a method 2100 that supports blind SCG configuration in MR-DC 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 communications manager as described with reference to FIGs. 14 through 17. 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 identify that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE. 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 DC configuration component as described with reference to FIGs. 14 through 17.

At 2110, the base station may transmit, to the UE, a release message indicating a suspension of SN communications for the UE. 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 a release message transmitter as described with reference to FIGs. 14 through 17.

At 2115, the base station may store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE. 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 MN lower-layer SCG configuration storage component as described with reference to FIGs. 14 through 17.

At 2120, the base station may receive a message from the UE that the SN communications are to resume. 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 resume SN communications component as described with reference to FIGs. 14 through 17.

At 2125, the base station may receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications. 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 lower-layer SCG configuration indication receiver as described with reference to FIGs. 14 through 17.

FIG. 22 shows a flowchart illustrating a method 2200 that supports blind SCG configuration in MR-DC 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 communications manager as described with reference to FIGs. 14 through 17. 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 that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE. 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 DC configuration component as described with reference to FIGs. 14 through 17.

At 2210, the base station may transmit, to the UE, a release message indicating a suspension of SN communications for the UE. 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 release message transmitter as described with reference to FIGs. 14 through 17.

At 2215, the base station may transmit, to the UE, an indication to store the lower-layer SCG configuration. 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 a lower-layer SCG configuration storage indicator as described with reference to FIGs. 14 through 17.

At 2220, the base station may store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE. 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 MN lower-layer SCG configuration storage component as described with reference to FIGs. 14 through 17.

At 2225, the base station may receive a message from the UE that the SN communications are to resume. The operations of 2225 may be performed according to the methods described herein. In some examples, aspects of the operations of 2225 may be performed by a resume SN communications component as described with reference to FIGs. 14 through 17.

At 2230, the base station may receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications. The operations of 2230 may be performed according to the methods described herein. In some examples, aspects of the operations of 2230 may be performed by a lower-layer SCG configuration indication receiver as described with reference to FIGs. 14 through 17.

FIG. 23 shows a flowchart illustrating a method 2300 that supports blind SCG configuration in MR-DC 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 communications manager as described with reference to FIGs. 14 through 17. 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 that the base station is operating in a DC configuration with a UE, where the base station is a MN with respect to DC communications with the UE. 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 DC configuration component as described with reference to FIGs. 14 through 17.

At 2310, the base station may transmit, to the UE, a release message indicating a suspension of SN communications for the UE. 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 release message transmitter as described with reference to FIGs. 14 through 17.

At 2315, the base station may transmit, to the UE, a measurement configuration for a SCG including a SN of the DC configuration, where the indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications is received based on the measurement configuration. 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 SCG measurement configuration component as described with reference to FIGs. 14 through 17.

At 2320, the base station may store, at the MN, a lower-layer SCG configuration used for the SN communications by the UE. 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 a MN lower-layer SCG configuration storage component as described with reference to FIGs. 14 through 17.

At 2325, the base station may receive a message from the UE that the SN communications are to resume. 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 resume SN communications component as described with reference to FIGs. 14 through 17.

At 2330, the base station may receive an indication from the UE whether the stored lower-layer SCG configuration is to be used for the SN communications. The operations of 2330 may be performed according to the methods described herein. In some examples, aspects of the operations of 2330 may be performed by a lower-layer SCG configuration indication receiver as described with reference to FIGs. 14 through 17.

At 2335, the base station may receive, from the UE, assistance information based on transmitting the measurement configuration, where the assistance information includes an indication to apply the stored lower-layer SCG configuration for the UE to use for SN communications or an identifier of a primary secondary cell for the UE to use for the SN communications. The operations of 2335 may be performed according to the methods described herein. In some examples, aspects of the operations of 2335 may be performed by a SCG measurement configuration component as described with reference to FIGs. 14 through 17.

At 2340, the base station may transmit, to the UE, a lower-layer configuration for the SCG for the SN communications based on the assistance information. The operations of 2340 may be performed according to the methods described herein. In some examples, aspects of the operations of 2340 may be performed by a SCG measurement configuration component as described with reference to FIGs. 14 through 17.

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 that the UE is operating in a dual connectivity configuration with a master node and a secondary node, wherein the UE is in an inactive communications state with the secondary node;

determining that secondary node communications are to resume;

determining whether a previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications; and

transmitting an indication to the master node indicating whether the previously stored lower-layer secondary cell group configuration can be used to resume the secondary node communications.
The method of claim 1, further comprising:

receiving, with a release message instructing the UE to enter the inactive communications state, an indication that the UE is to store a lower-layer secondary cell group configuration; and

storing the lower-layer secondary cell group configuration such that the lower-layer secondary cell group configuration becomes the previously stored lower-layer secondary cell group configuration.
The method of claim 2, wherein determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

identifying, from information included with the release message, a validity area which defines one or more cells in which the previously stored lower-layer secondary cell group configuration is valid for use; and

determining whether the UE is within the one or more cells defined by the validity area.
The method of claim 3, wherein the validity area comprises a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a radio access network (RAN) notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.
The method of claim 2, wherein determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

identifying, from information included with the release message, a validity time which defines a period in which the previously stored lower-layer secondary cell group configuration is valid; and

determining whether the previously stored lower-layer secondary cell group configuration is valid based at least in part on the validity time.
The method of claim 2, wherein determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

identifying, from information included with the release message, a threshold measurement value;

measuring signal reception conditions for comparison with the threshold measurement value; and

determining whether the previously stored lower-layer secondary cell group configuration is valid based at least in part on the signal reception condition measurements satisfying the threshold measurement value.
The method of claim 6, wherein the threshold measurement value comprises a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof.
The method of claim 2, further comprising:

discarding the previously stored lower-layer secondary cell group configuration based at least in part on determining the previously stored lower-layer secondary cell group configuration not being valid.
The method of claim 1, further comprising:

receiving, with a release message instructing the UE to enter the inactive communications state, a measurement configuration for a secondary cell group comprising the secondary node of the dual connectivity configuration.
The method of claim 9, wherein determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

performing measurements in accordance with the measurement configuration; and

determining whether to include the indication that the previously stored lower-layer secondary cell group configuration is available for resuming the secondary node communications based at least in part on the measurements.
The method of claim 10, further comprising:

receiving, from the master node and in response to the indication, a lower-layer secondary cell configuration to be used by the UE for the secondary node communications, wherein the lower-layer secondary cell configuration is either the previously stored lower-layer secondary cell group configuration, as stored by the master node, or an updated lower-layer secondary cell group configuration.
The method of claim 11, wherein receiving the lower-layer secondary cell configuration comprises:

receiving the lower-layer secondary cell configuration in a resume communications message or a reconfiguration message.
The method of claim 11, further comprising:

transmitting, to the master node and in addition to transmission of the indication, assistance information based at least in part on the measurements made in accordance with the measurement configuration, wherein the assistance information includes information to assist the master node in determining whether to apply the previously stored lower-layer secondary cell group configuration or the updated lower-layer secondary cell group configuration.
The method of claim 1, further comprising:

storing a higher-layer secondary cell group configuration based at least in part on receiving a release message.
The method of claim 1, wherein the master node operates in a first radio access technology and the secondary node operates in a second radio access technology.
The method of claim 1, wherein the previously stored lower-layer secondary cell group configuration comprises at least one of an identifier for the secondary node of the dual connectivity configuration, parameters for the secondary node communications, or configuration information for one or more cells of a secondary cell group for the secondary node communications.
A method for wireless communications at a base station, comprising:

identifying that the base station is operating in a dual connectivity configuration with a user equipment (UE) , wherein the base station is a master node with respect to dual connectivity communications with the UE;

transmitting, to the UE, a release message indicating a suspension of secondary node communications for the UE;

storing, at the master node, a lower-layer secondary cell group configuration used for the secondary node communications by the UE;

receiving a message from the UE that the secondary node communications are to resume; and

receiving an indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications.
The method of claim 17, wherein transmitting the release message comprises:

transmitting, to the UE, an indication to store the lower-layer secondary cell group configuration.
The method of claim 18, further comprising:

transmitting with the indication to store the lower-layer secondary cell group configuration, information comprising a validity area which defines one or more cells in which the UE is to be located if the stored lower-layer secondary cell group configuration is to be valid.
The method of claim 19, wherein the validity area of the one or more cells comprises a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a radio access network (RAN) notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.
The method of claim 18, further comprising:

transmitting with the indication to store the lower-layer secondary cell group configuration, information comprising a validity timer which defines a timing for when the stored lower-layer secondary cell group configuration is valid.
The method of claim 18, further comprising:

transmitting with the indication to store the lower-layer secondary cell group configuration, information comprising a threshold measurement value to allow the UE to determine whether the stored lower-layer secondary cell group configuration is to be applied.
The method of claim 22, wherein the threshold measurement value comprises a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof.
The method of claim 17, further comprising:

discarding the stored lower-layer secondary cell group configuration based at least in part on receiving the indication from the UE that the stored lower-layer secondary cell group configuration is not to be used.
The method of claim 17, wherein transmitting the release message comprises:

transmitting, to the UE, a measurement configuration for a secondary cell group comprising a secondary node of the dual connectivity configuration, wherein the indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications is received based at least in part on the measurement configuration.
The method of claim 25, further comprising:

receiving, from the UE, assistance information based at least in part on transmitting the measurement configuration, wherein the assistance information comprises an indication to apply the stored lower-layer secondary cell group configuration for the UE to use for secondary node communications or an identifier of a primary secondary cell for the UE to use for the secondary node communications; and

transmitting, to the UE, a lower-layer configuration for the secondary cell group for the secondary node communications based at least in part on the assistance information.
The method of claim 26, wherein the lower-layer configuration for the secondary cell group is transmitted in a resume communications message or a reconfiguration message.
The method of claim 17, further comprising:

transmitting, to a secondary node of the dual connectivity configuration, an activation request message for the secondary node communications based at least in part on receiving the message from the UE that the secondary node communications are to resume; and

transmitting, to the UE, a resume communications message for the secondary node communications based at least in part on receiving the indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications, wherein the resume communications message and the activation request message are transmitted simultaneously.
The method of claim 17, further comprising:

initiating a validity timer based at least in part on transmitting the release message;

determining that the validity timer expires prior to receiving the message from the UE that the secondary node communications are to resume; and

discarding the stored lower-layer secondary cell group configuration used for the secondary node communications by the UE based at least in part on the validity timer expiring.
The method of claim 17, wherein the master node operates in a first radio access technology and a secondary node operates in a second radio access technology.
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 that the UE is operating in a dual connectivity configuration with a master node and a secondary node, wherein the UE is in an inactive communications state with the secondary node;

determine that secondary node communications are to resume;

determine whether a previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications; and

transmit an indication to the master node indicating whether the previously stored lower-layer secondary cell group configuration can be used to resume the secondary node communications.
The apparatus of claim 31, wherein the instructions are further executable by the processor to cause the apparatus to:

receive, with a release message instructing the UE to enter the inactive communications state, an indication that the UE is to store a lower-layer secondary cell group configuration; and

store the lower-layer secondary cell group configuration such that the lower-layer secondary cell group configuration becomes the previously stored lower-layer secondary cell group configuration.
The apparatus of claim 32, wherein the instructions to determine whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications are executable by the processor to cause the apparatus to:

identify, from information included with the release message, a validity area which defines one or more cells in which the previously stored lower-layer secondary cell group configuration is valid for use; and

determine whether the UE is within the one or more cells defined by the validity area.
The apparatus of claim 33, wherein the validity area comprises a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a radio access network (RAN) notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.
The apparatus of claim 32, wherein the instructions to determine whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications are executable by the processor to cause the apparatus to:

identify, from information included with the release message, a validity time which defines a period in which the previously stored lower-layer secondary cell group configuration is valid; and

determine whether the previously stored lower-layer secondary cell group configuration is valid based at least in part on the validity time.
The apparatus of claim 32, wherein the instructions to determine whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications are executable by the processor to cause the apparatus to:

identify, from information included with the release message, a threshold measurement value;

measure signal reception conditions for comparison with the threshold measurement value; and

determine whether the previously stored lower-layer secondary cell group configuration is valid based at least in part on the signal reception condition measurements satisfying the threshold measurement value.
The apparatus of claim 36, wherein the threshold measurement value comprises a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof.
The apparatus of claim 32, wherein the instructions are further executable by the processor to cause the apparatus to:

discard the previously stored lower-layer secondary cell group configuration based at least in part on determining the previously stored lower-layer secondary cell group configuration not being valid.
The apparatus of claim 31, wherein the instructions are further executable by the processor to cause the apparatus to:

receive, with a release message instructing the UE to enter the inactive communications state, a measurement configuration for a secondary cell group comprising the secondary node of the dual connectivity configuration.
The apparatus of claim 39, wherein the instructions to determine whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications are executable by the processor to cause the apparatus to:

perform measurements in accordance with the measurement configuration; and

determine whether to include the indication that the previously stored lower-layer secondary cell group configuration is available for resuming the secondary node communications based at least in part on the measurements.
The apparatus of claim 40, wherein the instructions are further executable by the processor to cause the apparatus to:

receive, from the master node and in response to the indication, a lower-layer secondary cell configuration to be used by the UE for the secondary node communications, wherein the lower-layer secondary cell configuration is either the previously stored lower-layer secondary cell group configuration, as stored by the master node, or an updated lower-layer secondary cell group configuration.
The apparatus of claim 41, wherein the instructions to receive the lower-layer secondary cell configuration are executable by the processor to cause the apparatus to:

receive the lower-layer secondary cell configuration in a resume communications message or a reconfiguration message.
The apparatus of claim 41, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to the master node and in addition to transmission of the indication, assistance information based at least in part on the measurements made in accordance with the measurement configuration, wherein the assistance information includes information to assist the master node in determining whether to apply the previously stored lower-layer secondary cell group configuration or the updated lower-layer secondary cell group configuration.
The apparatus of claim 31, wherein the instructions are further executable by the processor to cause the apparatus to:

store a higher-layer secondary cell group configuration based at least in part on receiving a release message.
The apparatus of claim 31, wherein the master node operates in a first radio access technology and the secondary node operates in a second radio access technology.
The apparatus of claim 31, wherein the previously stored lower-layer secondary cell group configuration comprises at least one of an identifier for the secondary node of the dual connectivity configuration, parameters for the secondary node communications, or configuration information for one or more cells of a secondary cell group for the secondary node communications.
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 that the base station is operating in a dual connectivity configuration with a user equipment (UE) , wherein the base station is a master node with respect to dual connectivity communications with the UE;

transmit, to the UE, a release message indicating a suspension of secondary node communications for the UE;

store, at the master node, a lower-layer secondary cell group configuration used for the secondary node communications by the UE;

receive a message from the UE that the secondary node communications are to resume; and

receive an indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications.
The apparatus of claim 47, wherein the instructions to transmit the release message are executable by the processor to cause the apparatus to:

transmit, to the UE, an indication to store the lower-layer secondary cell group configuration.
The apparatus of claim 48, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit with the indication to store the lower-layer secondary cell group configuration, information comprising a validity area which defines one or more cells in which the UE is to be located if the stored lower-layer secondary cell group configuration is to be valid.
The apparatus of claim 49, wherein the validity area of the one or more cells comprises a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a radio access network (RAN) notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.
The apparatus of claim 48, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit with the indication to store the lower-layer secondary cell group configuration, information comprising a validity timer which defines a timing for when the stored lower-layer secondary cell group configuration is valid.
The apparatus of claim 48, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit with the indication to store the lower-layer secondary cell group configuration, information comprising a threshold measurement value to allow the UE to determine whether the stored lower-layer secondary cell group configuration is to be applied.
The apparatus of claim 52, wherein the threshold measurement value comprises a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof.
The apparatus of claim 47, wherein the instructions are further executable by the processor to cause the apparatus to:

discard the stored lower-layer secondary cell group configuration based at least in part on receiving the indication from the UE that the stored lower-layer secondary cell group configuration is not to be used.
The apparatus of claim 47, wherein the instructions to transmit the release message are executable by the processor to cause the apparatus to:

transmit, to the UE, a measurement configuration for a secondary cell group comprising a secondary node of the dual connectivity configuration, wherein the indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications is received based at least in part on the measurement configuration.
The apparatus of claim 55, wherein the instructions are further executable by the processor to cause the apparatus to:

receive, from the UE, assistance information based at least in part on transmitting the measurement configuration, wherein the assistance information comprises an indication to apply the stored lower-layer secondary cell group configuration for the UE to use for secondary node communications or an identifier of a primary secondary cell for the UE to use for the secondary node communications; and

transmit, to the UE, a lower-layer configuration for the secondary cell group for the secondary node communications based at least in part on the assistance information.
The apparatus of claim 56, wherein the lower-layer configuration for the secondary cell group is transmitted in a resume communications message or a reconfiguration message.
The apparatus of claim 47, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to a secondary node of the dual connectivity configuration, an activation request message for the secondary node communications based at least in part on receiving the message from the UE that the secondary node communications are to resume; and

transmit, to the UE, a resume communications message for the secondary node communications based at least in part on receiving the indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications, wherein the resume communications message and the activation request message are transmitted simultaneously.
The apparatus of claim 47, wherein the instructions are further executable by the processor to cause the apparatus to:

initiate a validity timer based at least in part on transmitting the release message;

determine that the validity timer expires prior to receiving the message from the UE that the secondary node communications are to resume; and

discard the stored lower-layer secondary cell group configuration used for the secondary node communications by the UE based at least in part on the validity timer expiring.
The apparatus of claim 47, wherein the master node operates in a first radio access technology and a secondary node operates in a second radio access technology.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for identifying that the UE is operating in a dual connectivity configuration with a master node and a secondary node, wherein the UE is in an inactive communications state with the secondary node;

means for determining that secondary node communications are to resume;

means for determining whether a previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications; and

means for transmitting an indication to the master node indicating whether the previously stored lower-layer secondary cell group configuration can be used to resume the secondary node communications.
The apparatus of claim 61, further comprising:

means for receiving, with a release message instructing the UE to enter the inactive communications state, an indication that the UE is to store a lower-layer secondary cell group configuration; and

means for storing the lower-layer secondary cell group configuration such that the lower-layer secondary cell group configuration becomes the previously stored lower-layer secondary cell group configuration.
The apparatus of claim 62, wherein the means for determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

means for identifying, from information included with the release message, a validity area which defines one or more cells in which the previously stored lower-layer secondary cell group configuration is valid for use; and

means for determining whether the UE is within the one or more cells defined by the validity area.
The apparatus of claim 63, wherein the validity area comprises a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a radio access network (RAN) notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.
The apparatus of claim 62, wherein the means for determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

means for identifying, from information included with the release message, a validity time which defines a period in which the previously stored lower-layer secondary cell group configuration is valid; and

means for determining whether the previously stored lower-layer secondary cell group configuration is valid based at least in part on the validity time.
The apparatus of claim 62, wherein the means for determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

means for identifying, from information included with the release message, a threshold measurement value;

means for measuring signal reception conditions for comparison with the threshold measurement value; and

means for determining whether the previously stored lower-layer secondary cell group configuration is valid based at least in part on the signal reception condition measurements satisfying the threshold measurement value.
The apparatus of claim 66, wherein the threshold measurement value comprises a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof.
The apparatus of claim 62, further comprising:

means for discarding the previously stored lower-layer secondary cell group configuration based at least in part on determining the previously stored lower-layer secondary cell group configuration not being valid.
The apparatus of claim 61, further comprising:

means for receiving, with a release message instructing the UE to enter the inactive communications state, a measurement configuration for a secondary cell group comprising the secondary node of the dual connectivity configuration.
The apparatus of claim 69, wherein the means for determining whether the previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications comprises:

means for performing measurements in accordance with the measurement configuration; and

means for determining whether to include the indication that the previously stored lower-layer secondary cell group configuration is available for resuming the secondary node communications based at least in part on the measurements.
The apparatus of claim 70, further comprising:

means for receiving, from the master node and in response to the indication, a lower-layer secondary cell configuration to be used by the UE for the secondary node communications, wherein the lower-layer secondary cell configuration is either the previously stored lower-layer secondary cell group configuration, as stored by the master node, or an updated lower-layer secondary cell group configuration.
The apparatus of claim 71, wherein the means for receiving the lower-layer secondary cell configuration comprises:

means for receiving the lower-layer secondary cell configuration in a resume communications message or a reconfiguration message.
The apparatus of claim 71, further comprising:

means for transmitting, to the master node and in addition to transmission of the indication, assistance information based at least in part on the measurements made in accordance with the measurement configuration, wherein the assistance information includes information to assist the master node in determining whether to apply the previously stored lower-layer secondary cell group configuration or the updated lower-layer secondary cell group configuration.
The apparatus of claim 61, further comprising:

means for storing a higher-layer secondary cell group configuration based at least in part on receiving a release message.
The apparatus of claim 61, wherein the master node operates in a first radio access technology and the secondary node operates in a second radio access technology.
The apparatus of claim 61, wherein the previously stored lower-layer secondary cell group configuration comprises at least one of an identifier for the secondary node of the dual connectivity configuration, parameters for the secondary node communications, or configuration information for one or more cells of a secondary cell group for the secondary node communications.
An apparatus for wireless communications at a base station, comprising:

means for identifying that the base station is operating in a dual connectivity configuration with a user equipment (UE) , wherein the base station is a master node with respect to dual connectivity communications with the UE;

means for transmitting, to the UE, a release message indicating a suspension of secondary node communications for the UE;

means for storing, at the master node, a lower-layer secondary cell group configuration used for the secondary node communications by the UE;

means for receiving a message from the UE that the secondary node communications are to resume; and

means for receiving an indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications.
The apparatus of claim 77, wherein the means for transmitting the release message comprises:

means for transmitting, to the UE, an indication to store the lower-layer secondary cell group configuration.
The apparatus of claim 78, further comprising:

means for transmitting with the indication to store the lower-layer secondary cell group configuration, information comprising a validity area which defines one or more cells in which the UE is to be located if the stored lower-layer secondary cell group configuration is to be valid.
The apparatus of claim 79, wherein the validity area of the one or more cells comprises a list of the one or more cells, a physical cell identifier (PCI) list of the one or more cells, a radio access network (RAN) notification area (RNA) list of the one or more cells, a timing advance (TA) list of the one or more cells, or a combination thereof.
The apparatus of claim 78, further comprising:

means for transmitting with the indication to store the lower-layer secondary cell group configuration, information comprising a validity timer which defines a timing for when the stored lower-layer secondary cell group configuration is valid.
The apparatus of claim 78, further comprising:

means for transmitting with the indication to store the lower-layer secondary cell group configuration, information comprising a threshold measurement value to allow the UE to determine whether the stored lower-layer secondary cell group configuration is to be applied.
The apparatus of claim 82, wherein the threshold measurement value comprises a reference signal received power (RSRP) measurement, a reference signal received quality (RSRQ) measurement, or a combination thereof.
The apparatus of claim 77, further comprising:

means for discarding the stored lower-layer secondary cell group configuration based at least in part on receiving the indication from the UE that the stored lower-layer secondary cell group configuration is not to be used.
The apparatus of claim 77, wherein the means for transmitting the release message comprises:

means for transmitting, to the UE, a measurement configuration for a secondary cell group comprising a secondary node of the dual connectivity configuration, wherein the indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications is received based at least in part on the measurement configuration.
The apparatus of claim 85, further comprising:

means for receiving, from the UE, assistance information based at least in part on transmitting the measurement configuration, wherein the assistance information comprises an indication to apply the stored lower-layer secondary cell group configuration for the UE to use for secondary node communications or an identifier of a primary secondary cell for the UE to use for the secondary node communications; and

means for transmitting, to the UE, a lower-layer configuration for the secondary cell group for the secondary node communications based at least in part on the assistance information.
The apparatus of claim 86, wherein the lower-layer configuration for the secondary cell group is transmitted in a resume communications message or a reconfiguration message.
The apparatus of claim 77, further comprising:

means for transmitting, to a secondary node of the dual connectivity configuration, an activation request message for the secondary node communications based at least in part on receiving the message from the UE that the secondary node communications are to resume; and

means for transmitting, to the UE, a resume communications message for the secondary node communications based at least in part on receiving the indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications, wherein the resume communications message and the activation request message are transmitted simultaneously.
The apparatus of claim 77, further comprising:

means for initiating a validity timer based at least in part on transmitting the release message;

means for determining that the validity timer expires prior to receiving the message from the UE that the secondary node communications are to resume; and

means for discarding the stored lower-layer secondary cell group configuration used for the secondary node communications by the UE based at least in part on the validity timer expiring.
The apparatus of claim 77, wherein the master node operates in a first radio access technology and a secondary node operates in a second radio access technology.
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 that the UE is operating in a dual connectivity configuration with a master node and a secondary node, wherein the UE is in an inactive communications state with the secondary node;

determine that secondary node communications are to resume;

determine whether a previously stored lower-layer secondary cell group configuration can be used for the resumption of secondary node communications; and

transmit an indication to the master node indicating whether the previously stored lower-layer secondary cell group configuration can be used to resume the secondary node communications.
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 that the base station is operating in a dual connectivity configuration with a user equipment (UE) , wherein the base station is a master node with respect to dual connectivity communications with the UE;

transmit, to the UE, a release message indicating a suspension of secondary node communications for the UE;

store, at the master node, a lower-layer secondary cell group configuration used for the secondary node communications by the UE;

receive a message from the UE that the secondary node communications are to resume; and

receive an indication from the UE whether the stored lower-layer secondary cell group configuration is to be used for the secondary node communications.