WO2021092847A1

WO2021092847A1 - Dedicated group of rach opportunities for a class of user equipments

Info

Publication number: WO2021092847A1
Application number: PCT/CN2019/118440
Authority: WO
Inventors: Qiaoyu Li; Chao Wei; Jing LEI; Hao Xu; Peter Pui Lok Ang
Original assignee: Qualcomm Incorporated
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2021-05-20
Also published as: WO2021093649A1

Abstract

In an aspect, a BS may transmit a downlink signal to a UE. The UE may perform signal quality measurement(s) on the downlink signal. The UE may select an RO group from among a plurality of RO groups based on the signal quality measurement(s). The UE may transmit a preamble associated with a RACH procedure on the selected RO group, with the selected RO group being indicative of a characteristic of the signal quality measurement(s). A particular RO group among the plurality of RO groups is dedicated to a particular UE class (e.g., NR-Light UEs).

Description

DEDICATED GROUP OF RACH OPPORTUNITIES FOR A CLASS OF USER EQUIPMENTS

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

Aspects of the disclosure relate generally to wireless communications and to techniques and apparatuses related to a dedicated group of Reverse Access Channel (RACH) opportunities (ROs) for a class of user equipments (UEs) .

2. Description of the Related Art

Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G) , a second-generation (2G) digital wireless phone service (including interim 2.5G networks) , a third-generation (3G) high speed data, Internet-capable wireless service, and a fourth-generation (4G) service (e.g., Long-Term Evolution (LTE) , WiMax) . There are presently many different types of wireless communication systems in use, including cellular and personal communications service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS) , and digital cellular systems based on code division multiple access (CDMA) , frequency division multiple access (FDMA) , time division multiple access (TDMA) , the Global System for Mobile access (GSM) variation of TDMA, etc.

A fifth generation (5G) mobile standard calls for higher data transfer speeds, greater numbers of connections, and better coverage, among other improvements. The 5G standard (also referred to as “New Radio” or “NR” ) , according to the Next Generation Mobile Networks Alliance, is designed to provide data rates of several tens of megabits per second to each of tens of thousands of users, with 1 gigabit per second to tens of workers on an office floor. Several hundreds of thousands of simultaneous connections should be supported in order to support large sensor deployments. Consequently, the spectral efficiency of 5G mobile communications should be significantly enhanced compared to the current 4G /LTE standard. Furthermore, signaling efficiencies should be enhanced and latency should be substantially reduced compared to current standards.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

Starting in 3GPP Rel. 17, a number of UE types are being allocated a new UE classification denoted as ‘NR-Light’ . Examples of UE types that fall under the NR-Light classification include wearable devices (e.g., smart watches, etc. ) , industrial sensors, video cameras (e.g., surveillance cameras, etc. ) , and so on. Generally, the UE types grouped under the NR-Light classification are associated with lower communicative capacity. For example, relative to ‘normal’ UEs (e.g., UEs not classified as NR-Light) , NR-Light UEs may be limited in terms of maximum bandwidth (e.g., 5 MHz, 10 MHz, 20 MHz, etc. ) , maximum transmission power (e.g., 20 dBm, 14 dBm, etc. ) , number of receive antennas (e.g., 1 receive antenna, 2 receive antennas, etc. ) , and so on. Some NR-Light UEs may also be sensitive in terms of power consumption (e.g., requiring a long battery life, such as several years) and may be highly mobile. Moreover, in some designs, it is generally desirable for NR-Light UEs to co-exist with UEs implementing protocols such as eMBB, URLLC, LTE NB-IoT/MTC, and so on.

Some UEs, such as NR-Light UEs, have a lower maximum transmission power than other UE types, which may result in transmission failure for a Msg-3 of a 4-Step PRACH procedure. Conventional systems do not permit a Msg-3 repetition level to be indicated via Msg-1.

Embodiments of the disclosure are directed at least in part to grouping particular RACH opportunities (ROs) together for association with particular classes of UEs. For example, a first group of ROs may be associated with a first UE class (e.g., including power-constrained UEs such as NR-Light UEs) , whereas a second group of ROs may be associated with both the first UE class and a second UE class (e.g., UEs that do not have the power constraints associated with the first UE class) .

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE may perform one or more signal reception quality measurements associated with a downlink signal on a downlink channel. The UE may further select a group of ROs among a plurality of groups of ROs based on the one or more signal reception quality measurements, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class. The UE may further transmit a preamble associated with a RACH procedure on the selected group of ROs.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a base station. The base station may transmit a downlink signal on a downlink channel. The base station may further receive, from a UE belonging to a first UE class based on one or more signal reception quality measurements of the downlink signal at the UE, a preamble associated with a RACH procedure over one group among a plurality of groups of ROs, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class. In an aspect, the group of ROs over which the preamble is received is indicative of a characteristic of the one or more signal reception quality measurements

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, cIoT user equipment, base station, wireless communication device, and/or processing system as substantially described with reference to and as illustrated by the drawings, and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is diagram illustrating an example of a wireless communication network.

FIG. 2 is a diagram illustrating an example of a base station in communication with a UE in a wireless communication network.

FIG. 3 illustrates a 4-Step Physical Random Access Channel (PRACH) procedure in accordance with an embodiment of the disclosure.

FIG. 4A illustrates examples of preamble transmission schemes that are characterized as long preambles in accordance with an embodiment of the disclosure.

FIG. 4B illustrates examples of preamble transmission schemes that are characterized as short preambles in accordance with an embodiment of the disclosure.

FIG. 5 illustrates an exemplary process of wireless communications according to an aspect of the disclosure.

FIG. 6 illustrates an exemplary process of wireless communications according to an aspect of the disclosure.

FIG. 7 illustrates an example implementation of the processes of FIGS. 5-6 in accordance with an embodiment of the disclosure.

FIG. 8 illustrates Reverse Access Channel (RACH) opportunity (RO) configurations in accordance with an embodiment of the disclosure.

FIG. 9 is a conceptual data flow diagram illustrating data flow between different means/components according to an aspect of the disclosure.

FIG. 10 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system according to an aspect of the disclosure.

FIG. 11 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system according to another aspect of the disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purposes of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and/or the like (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs) , field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, and/or the like, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , compact disk ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

It should be noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including 5G technologies.

FIG. 1 is a diagram illustrating a wireless network 100 in which aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G network. The wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, a 5G BS, a Node B, a gNB, a 5G NB, an access point, a transmit receive point (TRP) , and/or the like. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having association with the femto cell (e.g., UEs in a closed subscriber group (CSG) ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIG. 1, a BS 110a may be a macro BS for a macro cell 102a, a BS 110b may be a pico BS for a pico cell 102b, and a BS 110c may be a femto BS for a femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB” , “base station” , “5G BS” , “gNB” , “TRP” , “AP” , “node B” , “5G NB” , and “cell” may be used interchangeably herein.

In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

Wireless network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in FIG. 1, a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, macro BSs may have a high transmit power level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 Watts) .

A network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs. Network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.

UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, etc. A UE may be a cellular phone (e.g., a smart phone) , a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet) ) , an entertainment device (e.g., a music or video device, or a satellite radio) , a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolved or enhanced machine-type communication (eMTC) UEs. “MTC” may refer to MTC or eMTC. MTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a base station, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, and/or may be implemented as NB-IoT (narrowband internet of things) devices. IoT UEs, eMTC UEs, coverage enhancement (CE) mode UEs, bandwidth-limited (BL) UEs, and other types of UEs that operate using diminished power consumption relative to a baseline UE may be referred to herein as cellular IoT (cIoT) UEs. Some UEs may be considered a Customer Premises Equipment (CPE) . UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular RAT and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, and/or the like. A frequency may also be referred to as a carrier, a frequency channel, and/or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, 5G RAT networks may be deployed.

In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within the scheduling entity’s service area or cell. Within the present disclosure, as discussed further below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Access to the air interface may be controlled, for example, using a unified access control (UAC) system in which UEs are associated with an access identity (e.g., an access class and/or the like) , which may aim to ensure that certain high-priority UEs (e.g., emergency response UEs, mission critical UEs, and/or the like) can access the air interface even in congested conditions. Updates to the UAC parameters (e.g., priority levels associated with access identities, which access identities are permitted to access the air interface, and/or the like) may be provided for cIoT UEs using a message, such as a paging message or a direct indication information, which may conserve battery power of cIoT UEs.

Base stations are not the only entities that may function as a scheduling entity. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (e.g., one or more other UEs) . In this example, the UE is functioning as a scheduling entity, and other UEs utilize resources scheduled by the UE for wireless communication. A UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may optionally communicate directly with one another in addition to communicating with the scheduling entity.

Thus, in a wireless communication network with a scheduled access to time–frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.

As indicated above, FIG. 1 is provided merely as an example. Other examples may differ from what is described with regard to FIG. 1.

FIG. 2 shows a block diagram 200 of a design of base station 110 and UE 120, which may be one of the base stations and one of the UEs in FIG. 1. Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T ≥ 1 and R ≥ 1.

At base station 110, a transmit processor 220 may receive data from a data source 212 for one or more UEs, may select a modulation and coding scheme (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) , and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for orthogonal frequency divisional multiplexing (OFDM) and/or the like) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE 120, antennas 252a through 252r may receive the downlink signals from base station 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM and/or the like) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive (RX) processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller/processor 280. A channel processor may determine reference signal received power (RSRP) , received signal strength indicator (RSSI) , a reference signal received quality (RSRQ) , a channel quality indicator (CQI) , and/or the like.

On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor 280. Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, and/or the like) , and transmitted to base station 110. At base station 110, the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by UE 120. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller/processor 240. Base station 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244. Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.

Controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of FIG. 2 may perform one or more techniques associated with UAC parameter updating, as described in more detail elsewhere herein. For example, controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of FIG. 2 may perform or direct operations of, for example, process 500 of FIG. 5, and/or other processes as described herein.

Memories

242 and 282 may store data and program codes for BS 110 and UE 120, respectively. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

As indicated above, FIG. 2 is provided merely as an example. Other examples may differ from what is described with regard to FIG. 2.

As noted above, various device types may be characterized as UEs. Starting in 3GPP Rel. 17, a number of these UE types are being allocated a new UE classification denoted as ‘NR-Light’ . Examples of UE types that fall under the NR-Light classification include wearable devices (e.g., smart watches, etc. ) , industrial sensors, video cameras (e.g., surveillance cameras, etc. ) , and so on. Generally, the UE types grouped under the NR-Light classification are associated with lower communicative capacity. For example, relative to ‘normal’ UEs (e.g., UEs not classified as NR-Light) , NR-Light UEs may be limited in terms of maximum bandwidth (e.g., 5 MHz, 10 MHz, 20 MHz, etc. ) , maximum transmission power (e.g., 20 dBm, 14 dBm, etc. ) , number of receive antennas (e.g., 1 receive antenna, 2 receive antennas, etc. ) , and so on. Some NR-Light UEs may also be sensitive in terms of power consumption (e.g., requiring a long battery life, such as several years) and may be highly mobile. Moreover, in some designs, it is generally desirable for NR-Light UEs to co-exist with UEs implementing protocols such as eMBB, URLLC, LTE NB-IoT/MTC, and so on.

FIG. 3 illustrates a 4-Step Physical Random Access Channel (PRACH) procedure 300 in accordance with an embodiment of the disclosure. The 4-Step PRACH procedure 300 is an initial access procedure by which a UE (e.g., UE 120) can initiate communication with a BS (e.g., BS 110) .

Referring to FIG. 3, at 302, a Message 1 ( “Msg-1” ) of the 4-Step PRACH procedure 300 is transmitted by UE 120 to BS 110. The Msg-1 of 302 may be characterized herein as a PRACH preamble. In an example, the Msg-1 of 302 may be implemented a Zadoff-Chu sequence which indicates the presence of a random access attempt and allows BS 110 to estimate between BS 110 and UE 120.

Referring to FIG. 3, at 304, a Message 2 ( “Msg-2” ) of the 4-Step PRACH procedure 300 is transmitted by BS 110 to UE 120. The Msg-2 of 304 may be characterized herein as a random access response (RAR) . For example, in response to the detected PRACH preamble (or Msg-1) at 302, BS 110 may transmit the Msg-2 of 304 on a downlink (DL) shared channel (SCH) comprising any combination of:

· An index of the detected PRACH preamble (or Msg-1) from 302,

· An uplink timing correction for UE 120,

· A scheduling grant indicating what resource (s) UE 120 should use for transmission of Message 3 ( “Msg-3” ) of the 4-Step PRACH procedure 300, and

· A Temporary Cell Radio Network Temporary Identifier (TC-RNTI) used for further communication between UE 120 and BS 110.

In an example, the Msg-2 of 304 may be scheduled on the SL SCH and indicated on a Physical Downlink Control Channel (PDCCH) using an identity (e.g., a Random Access RNTI (RA-RNTI) which is indicated by the time and frequency resource (s) upon which the PRACH preamble (or Msg-1) from 302 is transmitted.

Referring to FIG. 3, at 306, a Message 3 ( “Msg-3” ) comprising at least a UE identifier (ID) of UE 120 is transmitted by UE 120 to BS 110. In some designs, the Msg-3 is transmitted over Physical Uplink Shared Channel (PUSCH) and may be referred to as a Msg-3 PUSCH. In an example, the Msg-3 transmitted at 306 may be transmitted via the UL SCH resource (s) indicated by the Msg-2 from 304. In some designs, device scrambling is used for the transmission of Msg-3 at 306 (e.g., scrambling based on the TC-RNTI assigned via the Msg-2 from 304) . In some designs, if UE 120 is in a radio resource control (RRC) -Connected state with a C-RNTI already assigned thereto, the C-RNTI may be used as the UE-ID in the Msg-3 at 306. In some designs, if UE 120 is not in a RRC-Connected state, a core network device identifier such as a 40-bit Serving Temporary Mobile Subscriber Identity (S-TMSI) can be used as the UE-ID in the Msg-3 at 306.

Referring to FIG. 3, at 308, another Msg-3 is optionally transmitted as a hybrid automatic repeat request (HARQ) acknowledgment (ACK) to the Msg-2 from 304. In some designs, the Msg-3 is transmitted via PUCCH and may be referred to as a Msg-3 PUCCH. In some designs, whether or not the Msg-3 PUCCH is transmitted at 308 may be configured via RRC signaling or via one or more information elements (IEs) in a system information block (SIB) .

Referring to FIG. 3, at 308, a Message 4 ( “Msg-4” ) of the 4-Step PRACH procedure 300 is transmitted by BS 110 to UE 120. In some designs, the Msg-4 of 308 comprises a downlink message for contention resolution as there is some probability of contention associated with the Msg-3 transmissions at 306-308. For example, if multiple UEs transmit the same Msg-1 (302) at the same time, then the multiple UEs may react to the same Msg-2 (304) such that a collision occurs. In some designs, if UE 120 already has a C-RNTI assigned, contention resolution may be handled by addressing UE 120 on the PDCCH using the C-RNTI. In some designs, if UE 120 does not have a valid C-RNTI (e.g., UE 120 is RRC-Idle prior to 302) , Msg-4 contention resolution may be handled by addressing UE 120 on the PDCCH using the TC-RNTI, with UE 120 comparing (i) the UE-ID received within a PDSCH scheduled by the PDCCH of Msg-4 with (ii) the UE-ID transmitted in the Msg-3 PUSCH at 306, so as to determine the 4-Step PRACH procedure 300 successful if a match is observed, after which the TC-RNTI is confirmed as C-RNTI.

The PRACH preamble (e.g., Msg-1 at 302 of FIG. 3) may be configured in accordance with any of a variety of preamble transmission schemes, which are generally classified as either long preambles or short preambles. In some designs, a total of 13 preamble transmission schemes are defined. FIG. 4A illustrates examples of preamble transmission schemes 400A that are characterized as long preambles in accordance with an embodiment of the disclosure. FIG. 4B illustrates examples of preamble transmission schemes 400B that are characterized as short preambles in accordance with an embodiment of the disclosure. As shown with respect to FIGS. 4A-4B, the various preamble transmission schemes 400A-400B may differ in terms of various parameters, including by way of example one or more of:

· Preamble format,

· Sequence length (e.g., denoted as “L” in FIGS. 4A-4B) ,

· Numerology or sub-carrier spacing (SCS) ,

· Bandwidth,

· Cycling Prefix (CP) duration,

· Guard Time (GT) duration,

· Total length, and/or

· Number of OFDM symbols.

In a scenario where UE 120 corresponds to a particular class of UE, such as an NR-Light UE, it is possible that the Msg-1 at 302 is successfully received at BS 110, but Msg-3 at 306 (e.g., and/or the optional Msg-3 PUCCH at 308) is not successfully received at BS 110. For example, Msg-1 at 302 may be based on relatively long preamble sequences which can be received reliably at BS 110, whereas Msg-3 at 306 (e.g., and/or the optional Msg-3 PUCCH at 308) can be based on OFDM signals and may comprise a larger payload than the Msg-1 at 302 which requires more transmission power to reliably transmit. However, some UEs, such as NR-Light UEs, have a lower maximum transmission power than other UE types, which may result in transmission failure for the Msg-3 at 306 (e.g., and/or the optional Msg-3 PUCCH at 308) . For power-constrained UEs, the Msg-3 at 306 (e.g., and/or the optional Msg-3 PUCCH at 308) could be transported more reliability via the use of one or more transmission repetitions. However, conventional systems do not permit a Msg-3 repetition level to be indicated via Msg-1.

Embodiments of the disclosure are directed at least in part to grouping particular RACH opportunities (ROs) together for association with particular classes of UEs. For example, a first group of ROs may be associated with a first UE class (e.g., including power-constrained UEs such as NR-Light UEs) , whereas a second group of ROs may be associated with both the first UE class and a second UE class (e.g., UEs that do not have the power constraints associated with the first UE class) . In some designs, a Msg-1 transported via the first group of ROs may be configured to indicate to the network that subsequent Msg-3 PUSCH (and/or the optional Msg-3 PUCCH) will be transmitted with repetitions. As used herein, a “group” of ROs refers to a grouping of one or more ROs.

FIG. 5 illustrates an exemplary process 500 of wireless communications according to an aspect of the disclosure. The process 500 of FIG. 5 is performed by UE 120.

At 502, UE 120 (e.g., antenna (s) 252a ... 252r, demodulators (s) 254a ... 254r, MIMO detector 256, RX processor 258) optionally receives, from a base station, information associated with a plurality of groups of ROs. In some designs, 502 is optional because this information may alternatively be pre-defined (e.g., via the relevant 3GPP standard) . In an example, the received information at 502 may comprise at least one time and frequency block associated at least one of the plurality of groups of ROs, at least one preamble transmission scheme associated one or more of the plurality of groups of ROs, at least one threshold by which UEs in the first UE class can select among the plurality of groups of ROs, or any combination thereof. In some designs, the received information at 502 may be received from the base station via one or more SIBs (e.g., SIB1) or via RRC signaling.

At 504, UE 120 (e.g., antenna (s) 252a ... 252r, demodulators (s) 254a ... 254r, MIMO detector 256, RX processor 258) performs one or more signal reception quality measurements associated with a downlink signal on a downlink channel. In some designs, the downlink signal may be a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) , and the one or more signal reception quality measurements comprise at least an RSRP of the downlink signal.

At 506, UE 120 (e.g., controller/processor 280) selects a group of ROs among the plurality of groups of ROs based on the one or more signal reception quality measurements. In particular, the plurality of groups of ROs may comprise a first group of ROs dedicated to the first UE class (e.g., power-constrained UEs such as NR-Light UEs) . In an example, the plurality of groups of ROs may further comprise a second group of ROs shared between the first UE class and a second UE class (e.g., UEs that do not have the power constraints associated with the first UE class) . In an example, the selection of 506 may be based on a relationship between the one or more signal reception quality measurements and at least one signal reception quality measurement threshold. For example, at 506, the first group of ROs may be selected if the one or more signal reception quality measurements are less than the at least one signal reception quality measurement threshold, and the second group of ROs may be selected if the one or more signal reception quality measurements are not less than the at least one signal reception quality measurement threshold. In this case, in an example, lower- performing UEs of the first UE class may select the first group of ROs, while higher-performing UEs of the first UE class may select the second group of ROs (which may also be used by UEs of the second UE class without requiring execution of the process 500 of FIG. 5 thereon) . In some designs, the at least one signal reception quality measurement threshold is pre-defined (e.g., in the relevant 3GPP standard) , while in other designs the at least one signal reception quality measurement threshold is configured dynamically (e.g., via a SIB such as SIB1 or via RRC signaling) .

At 508, the UE 120 (e.g., antenna (s) 252a ... 252r, TX MIMO processor 266, modulators (s) 254a ... 254r, TX processor 264) transmits a preamble associated with a RACH procedure on the selected group of ROs. In an example, the preamble transmitted at 508 may correspond to a Msg-1 of a 4-Step PRACH procedure. In some designs, the preamble of 508 may be configured to indicate to the base station that subsequent Msg-3 PUSCH (and/or the optional Msg-3 PUCCH) will be transmitted with repetitions, as will be described below in more detail.

FIG. 6 illustrates an exemplary process 600 of wireless communications according to an aspect of the disclosure. The process 600 of FIG. 6 is performed by BS 110.

At 602, BS 110 (e.g., antenna (s) 234a ... 234t, modulators (s) 232a ... 232a, TX MIMO processor 230, TX processor 220) optionally transmits, to a UE, information associated with a plurality of groups of ROs. In some designs, 602 is optional because this information may alternatively be pre-defined (e.g., via the relevant 3GPP standard) . In an example, the transmitted information at 602 may comprise at least one time and frequency block associated at least one of the plurality of groups of ROs, at least one preamble transmission scheme associated one or more of the plurality of groups of ROs, at least one threshold by which UEs in the first UE class can select among the plurality of groups of ROs, or any combination thereof. In some designs, the transmitted information at 602 may be received from the base station via one or more SIBs (e.g., SIB1) or via RRC signaling.

At 604, BS 110 (e.g., antenna (s) 234a ... 234t, modulators (s) 232a ... 232a, TX MIMO processor 230, TX processor 220) transmits a downlink signal on a downlink channel. In some designs, the downlink signal may be a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) , and the one or more signal reception quality measurements comprise at least an RSRP of the downlink signal. In some designs, the downlink signal transmitted at 604 may be measured at the UE so as to produce one or more signal reception quality measurements as described above with respect to 504 of FIG. 5.

At 606, BS 110 (e.g., antenna (s) 234a ... 234t, demodulators (s) 232a ... 232a, MIMO detector 236, RX processor 238) receives, from a UE belonging to the first UE class based on the one or more signal reception quality measurements of the downlink signal at the UE, a preamble associated with a RACH procedure over one group among a plurality of groups of ROs. In particular, the plurality of groups of ROs may comprise a first group of ROs dedicated to the first UE class (e.g., power-constrained UEs such as NR-Light UEs) . In an example, the plurality of groups of ROs may further comprise a second group of ROs shared between the first UE class and a second UE class (e.g., UEs that do not have the power constraints associated with the first UE class) . In some designs, the group of ROs over which the preamble is received is indicative of a characteristic of the one or more signal reception quality measurements. For example, if a UE belonging to the first UE class sends the preamble of 606 over the first group of ROs, this may function as an indication that the one or more signal reception quality measurements are below at least one signal reception quality threshold. In an alternative example, if a UE belonging to the first UE class sends the preamble of 606 over the second group of ROs, this may function as an indication that the one or more signal reception quality measurements are not below at least one signal reception quality threshold. As noted above, in some designs, these threshold (s) may be pre-defined (e.g., in the relevant 3GPP standard) or may be dynamically configured (e.g., via SIB or RRC signaling) .

Referring to FIGS. 5-6, in some designs, the first group of ROs is associated with a first preamble transmission scheme and the second group of ROs is associated with a second preamble transmission scheme that is different than the first preamble transmission scheme. In an example, the first preamble transmission scheme differs from the second preamble transmission scheme in terms of at least one or more of preamble format, preamble sequence, a time-domain orthogonal cover code (OCC) across a respective set of slots, symbols, or ROs, or any combination thereof. For example, relative to the second group of ROs, the first group of ROs may be associated with a lower SCS, narrower bandwidth, higher slot-level repetition (e.g., optionally with time-domain OCC) higher symbol-level repetition.

Referring to FIGS. 5-6, in some designs, the second group of ROs is associated with a first preamble transmission scheme for use by UEs belonging to the first UE class and the second group of ROs is further associated with a second preamble transmission scheme for use by UEs belonging to the second UE class. So, even though UEs in both UE classes can use the second group of ROs, UEs in the respective UE classes do not necessarily use the second group of ROs in the same way. In some designs, the first preamble transmission scheme differs from the second preamble transmission scheme in terms of at least one or more of preamble format, SCS, bandwidth, slot-level repetition, a time-domain OCC across a respective set of slots, symbols, or ROs, symbol-level repetition, or any combination thereof. In some designs, the first preamble transmission scheme comprises one or more preamble sequences that are not used by the second preamble transmission scheme, or the first preamble transmission scheme comprises cross-RO repetition with a time-domain OCC that is not used by the second preamble transmission scheme, or any combination thereof.

FIG. 7 illustrates an example implementation 700 of the processes 500-600 of FIGS. 5-6 in accordance with an embodiment of the disclosure. The process 700 constitutes a modified version of the 4-Step PRACH procedure 300 of FIG 3. At 702 (e.g., as in 502 of FIG. 5 or 602 of FIG. 6) , BS 110 transmits RO group information to UE 120 (e.g., via SIB or RRC signaling) . As noted above, the RO group information may alternative be pre-defined, in which case 702 can be omitted. At 704 (e.g., as in 604 of FIG. 6) , BS 110 transmits a downlink signal (e.g., PSS/SSS) , and at 706 (e.g., as in 504 of FIG. 5) UE 120 receives and measures the downlink signal. At 708 (e.g., as in 506 of FIG. 5) , UE 120 selects a group of ROs based on the downlink signal measurement (s) from 706. At 710, UE 120 also selects a preamble sequence group to be used on the selected RO group. At 712 (e.g., as in 508 of FIG. 5 or 606 of FIG. 6) , UE 120 transmits Msg-1 (or PRACH preamble) to BS 110. At 714, BS 110 detects a Msg-3 repetition level from the Msg-1 of 712 (e.g., based on which preamble sequence group was used, etc. ) . At 716, BS 110 transmits Msg-2 to UE 120. At 718, UE 120 transmits Msg-3 PUSCH (s) to BS 110 (e.g., in accordance with an Msg-3 repetition level indicated by Msg-1) . At 720, UE 120 transmits Msg-3 PUCCH (s) to BS 110 (e.g., in accordance with an Msg-3 repetition level indicated by Msg-1) . At 720, BS 110 transmits Msg-4 to UE 120.

FIG. 8 illustrates RO configurations 800 in accordance with an embodiment of the disclosure. Referring to FIG. 8,

ROs

802 and 804 are wide in terms of bandwidth and thin in terms of time relative to

ROs

806, 808 and 810. In an example, RO 806 may be FDMed while ROs 808-810 are TDMed.

ROs

812 and 814 may correspond to separate RO segments that are used in association with a time-domain OCC preamble transmission. In FIG. 8, ROs 802-804 may form part of a group of ROs that are shared between UEs of the first and second UE classes, while ROs 806-814 may form part of a group of ROs that are dedicated to the first UE class (e.g., power-constrained UEs such as NR-Light UEs) .

FIG. 9 is a conceptual data flow diagram 900 illustrating the data flow between different means/components in

exemplary apparatuses

902 and 980 in accordance with an embodiment of the disclosure. The apparatus 902 may be a UE (e.g., UE 120) in communication with an apparatus 980, which may be a base station (e.g., base station 110) .

The apparatus 902 includes a transmission component 904, which may correspond to transmitter circuitry in UE 120 as depicted in FIG. 2, including controller/processor 280, antenna (s) 252a ... 252r, modulators (s) 254a ... 254r, TX MIMO processor 266, TX processor 264. The apparatus 902 further includes an RO group selection component 906, which may correspond to processor circuitry in UE 120 as depicted in FIG. 2, including controller/processor 280, etc. The apparatus 902 further includes a reception component 908, which may correspond to receiver circuitry in UE 120 as depicted in FIG. 2, including controller/processor 280, antenna (s) 252a ... 252r, demodulators (s) 254a ... 254r, MIMO detector 256, RX processor 258.

The apparatus 980 includes a reception component 982, which may correspond to receiver circuitry in BS 110 as depicted in FIG. 2, including controller/processor 240, antenna (s) 234a ... 234r, demodulators (s) 232a ... 232r, MIMO detector 236, RX processor 238, communication unit 244. The apparatus 980 further optionally includes an RO group information component 984, which may correspond to processor circuitry in BS 110 as depicted in FIG. 2, including controller/processor 240. The apparatus 980 further includes a transmission component 986, which may correspond to transmission circuitry in BS 110 as depicted in FIG. 2, including e.g., controller/processor 240, antenna (s) 234a ... 234r, modulators (s) 232a ... 232r, Tx MIMO processor 230, TX processor 220, communication unit 244.

Referring to FIG. 9, the RO group information component 906 optionally sends RO group information to the transmission component 986, which optionally transmits the RO group information to the reception component 908 (e.g., via SIB or RRC signaling) . The transmission component 986 may transmit a downlink signal, which is measured at the reception component 908. These measurement (s) of the downlink signal may be used by the RO group selection component 906 to facilitate selection of a group of ROs to use for Msg-1 transmission. The transmission component 904 transmits Msg-1 (PRACH preamble) , Msg-3 PUSCH (s) , and (optionally) Msg-3 PUCCH (s) to the reception component 982, and the transmission component 986 transmits Msg-2 and Msg-4 to the reception component 908.

One or more components of the apparatus 902 and apparatus 980 may perform each of the blocks of the algorithm in the aforementioned flowcharts of FIGS. 5-6. As such, each block in the aforementioned flowcharts of FIGS. 5-6 may be performed by a component and the apparatus 902 and apparatus 980 may include one or more of those components. The components may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 10 is a diagram 1000 illustrating an example of a hardware implementation for an apparatus 902 employing a processing system 1014. The processing system 1014 may be implemented with a bus architecture, represented generally by the bus 1024. The bus 1024 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1014 and the overall design constraints. The bus 1024 links together various circuits including one or more processors and/or hardware components, represented by the processor 1004, the

components

904, 906 and 908, and the computer-readable medium /memory 1006. The bus 1024 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1014 may be coupled to a transceiver 1010. The transceiver 1010 is coupled to one or more antennas 1020. The transceiver 1010 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1010 receives a signal from the one or more antennas 1020, extracts information from the received signal, and provides the extracted information to the processing system 1014, specifically the reception component 908. In addition, the transceiver 1010 receives information from the processing system 1014, specifically the transmission component 904, and based on the received information, generates a signal to be applied to the one or more antennas 1020. The processing system 1014 includes a processor 1004 coupled to a computer-readable medium /memory 1006. The processor 1004 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 1006. The software, when executed by the processor 1004, causes the processing system 1014 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 1006 may also be used for storing data that is manipulated by the processor 1004 when executing software. The processing system 1014 further includes at least one of the

components

904, 906 and 908. The components may be software components running in the processor 1004, resident/stored in the computer readable medium /memory 1006, one or more hardware components coupled to the processor 1004, or some combination thereof. The processing system 1014 may be a component of the UE 120 of FIG. 2 and may include the memory 282, and/or at least one of the TX processor 264, the RX processor 258, and the controller/processor 280.

In one configuration, the apparatus 902 (e.g., a UE) for wireless communication includes means for performing one or more signal reception quality measurements associated with a downlink signal on a downlink channel, means for selecting a group of ROs among a plurality of groups of ROs based on the one or more signal reception quality measurements, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class and a second group of ROs shared between the first UE class and a second UE class, and means for transmitting a preamble associated with a RACH procedure on the selected group of ROs. In some designs, the apparatus 902 may further include means for receiving, from a base station, information associated with the plurality of groups of ROs. The aforementioned means may be one or more of the aforementioned components of the apparatus 902 and/or the processing system 1014 of the apparatus 902 configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1014 may include the TX processor 264, the RX processor 258, and the controller/processor 280.

FIG. 11 is a diagram 1100 illustrating an example of a hardware implementation for an apparatus 980 employing a processing system 1114. The processing system 1114 may be implemented with a bus architecture, represented generally by the bus 1124. The bus 1124 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1114 and the overall design constraints. The bus 1124 links together various circuits including one or more processors and/or hardware components, represented by the processor 1104, the

components

982, 984 and 986, and the computer-readable medium /memory 1106. The bus 1124 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1114 may be coupled to a transceiver 1110. The transceiver 1110 is coupled to one or more antennas 1120. The transceiver 1110 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1110 receives a signal from the one or more antennas 1120, extracts information from the received signal, and provides the extracted information to the processing system 1114, specifically the reception component 982. In addition, the transceiver 1110 receives information from the processing system 1114, specifically the transmission component 986, and based on the received information, generates a signal to be applied to the one or more antennas 1120. The processing system 1114 includes a processor 1104 coupled to a computer-readable medium /memory 1106. The processor 1104 is responsible for general processing, including the execution of software stored on the computer-readable medium /memory 1106. The software, when executed by the processor 1104, causes the processing system 1114 to perform the various functions described supra for any particular apparatus. The computer-readable medium /memory 1106 may also be used for storing data that is manipulated by the processor 1104 when executing software. The processing system 1114 further includes at least one of the

components

982, 984 and 986. The components may be software components running in the processor 1104, resident/stored in the computer readable medium /memory 1106, one or more hardware components coupled to the processor 1104, or some combination thereof. The processing system 1114 may be a component of the BS 110 of FIG. 2 and may include the memory 242, and/or at least one of the TX processor 220, the RX processor 238, and the controller/processor 240.

In one configuration, the apparatus 980 (e.g., a BS) for wireless communication includes means for transmitting a downlink signal on a downlink channel, means for receiving, from a UE belonging to a first UE class based on one or more signal reception quality measurements of the downlink signal at the UE, a preamble associated with a RACH procedure over one group among a plurality of groups of ROs, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class and a second group of ROs shared between the first UE class and a second UE class, wherein the group of ROs over which the preamble is received is indicative of a characteristic of the one or more signal reception quality measurements. In some designs, the apparatus 980 may further include transmitting information associated with the plurality of groups of ROs. The aforementioned means may be one or more of the aforementioned components of the apparatus 980 and/or the processing system 1114 of the apparatus 980 configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1114 may include the TX processor 220, the RX processor 238, and the controller/processor 240.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and/or a combination of hardware and software.

As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware, firmware, and/or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like) , and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method of operating a user equipment (UE) belonging to a first UE class, comprising:

performing one or more signal reception quality measurements associated with a downlink signal on a downlink channel;

selecting a group of random access channel (RACH) opportunities (ROs) among a plurality of groups of ROs based on the one or more signal reception quality measurements, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class; and

transmitting a preamble associated with a RACH procedure on the selected group of ROs.
The method of claim 1, wherein the selecting among the plurality of ROs based on a relationship between the one or more signal reception quality measurements and at least one signal reception quality measurement threshold.
The method of claim 2,

wherein the selecting selects the first group of ROs if the one or more signal reception quality measurements are less than the at least one signal reception quality measurement threshold, and

wherein the selecting selects the second group of ROs if the one or more signal reception quality measurements are not less than the at least one signal reception quality measurement threshold, and
The method of claim 2,

wherein the at least one signal reception quality measurement threshold is pre-defined, or

wherein the at least one signal reception quality measurement threshold is configured via a system information block (SIB) or a radio resource configuration (RRC) signaling.
The method of claim 1, wherein the first group of ROs is associated with a first preamble transmission scheme and the second group of ROs is associated with a second preamble transmission scheme that is different than the first preamble transmission scheme.
The method of claim 5, wherein the first preamble transmission scheme differs from the second preamble transmission scheme in terms of at least one or more of:

preamble format,

preamble sequence,

a time-domain orthogonal cover code (OCC) across a respective set of slots, symbols, or ROs, or

any combination thereof.
The method of claim 1,

wherein the downlink signal is a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) , and

wherein the one or more signal reception quality measurements comprise at least a reference signal received power (RSRP) of the downlink signal.
The method of claim 1, further comprising:

receiving, from a base station, information associated with the plurality of groups of ROs.
The method of claim 8, wherein the received information comprises:

at least one time and frequency block associated at least one of the plurality of groups of ROs,

at least one preamble transmission scheme associated one or more of the plurality of groups of ROs,

at least one threshold by which UEs in the first UE class can select among the plurality of groups of ROs, or

any combination thereof.
The method of claim 9, wherein the received information is received via one or more system information blocks (SIBs) or via radio resource control (RRC) signaling.
The method of claim 1, wherein at least some information associated with the plurality of ROs is pre-defined.
The method of claim 1,

wherein the RACH procedure is a 4-Step PRACH procedure, and

wherein the preamble is a Msg-1 preamble of the 4-Step PRACH procedure.
The method of claim 1, wherein the plurality of group of ROs further comprises a second group of ROs shared between the first UE class and a second UE class
The method of claim 13, wherein transmissions on the second group of ROs by UEs belonging to the first class of UEs are associated with a first preamble transmission scheme and transmissions on the second group of ROs by UEs belonging to the second class of UEs are associated with a second preamble transmission scheme that is different than the first preamble transmission scheme.
The method of claim 14, wherein the first preamble transmission scheme differs from the second preamble transmission scheme in terms of at least one or more of:

preamble format,

subcarrier spacing (SCS) ,

bandwidth,

slot-level repetition,

a time-domain orthogonal cover code (OCC) across a respective set of slots, symbols, or ROs,

symbol-level repetition, or

any combination thereof.
The method of claim 14,

wherein the first preamble transmission scheme comprises one or more preamble sequences that are not used by the second preamble transmission scheme,

wherein the first preamble transmission scheme comprises cross-RO repetition with a time-domain orthogonal cover code (OCC) that is not used by the second preamble transmission scheme, or

any combination thereof.
A method of operating a base station, comprising:

transmitting a downlink signal on a downlink channel; and

receiving, from a UE belonging to a first UE class based on one or more signal reception quality measurements of the downlink signal at the UE, a preamble associated with a random access channel (RACH) procedure over one group among a plurality of groups of RACH opportunities (ROs) , the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class,

wherein the group of ROs over which the preamble is received is indicative of a characteristic of the one or more signal reception quality measurements.
The method of claim 17, further comprising:

transmitting information associated with the plurality of groups of ROs.
The method of claim 18, wherein the transmitted information comprises:

a time and frequency block associated with at least one of the plurality of groups of ROs,

at least one preamble transmission scheme associated with one or more of the plurality of groups of ROs,

at least one threshold by which UEs in the first UE class can select among the plurality of groups of ROs, or

any combination thereof.
The method of claim 18, wherein the transmitted information is transmitted via one or more system information blocks (SIBs) or via radio resource control (RRC) signaling.
The method of claim 17, wherein at least some information associated with the plurality of groups of ROs is pre-defined.
The method of claim 17, wherein the first group of ROs is associated with a first preamble transmission scheme and the second group of ROs is associated with a second preamble transmission scheme that is different than the first preamble transmission scheme.
The method of claim 22, wherein the first preamble transmission scheme differs from the second preamble transmission scheme in terms of at least one or more of:

preamble format,

preamble sequence,

a time-domain orthogonal cover code (OCC) across a respective set of slots, symbols, or ROs, or

any combination thereof.
The method of claim 17,

wherein the downlink signal is a primary synchronization signal (PSS) or a secondary synchronization signal (SSS) , and

wherein the one or more signal reception quality measurements comprise a reference signal received power (RSRP) of the downlink signal.
The method of claim 17,

wherein the RACH procedure is a 4-Step PRACH procedure, and

wherein the preamble is a Msg-1 preamble of the 4-Step PRACH procedure.
The method of claim 17, wherein the plurality of groups of ROs further comprises a second group of ROs shared between the first UE class and a second UE class
The method of claim 26, wherein transmissions on the second group of ROs by UEs belonging to the first class of UEs are associated with a first preamble transmission scheme and transmissions on the second group of ROs by UEs belonging to the second class of UEs are associated with a second preamble transmission scheme that is different than the first preamble transmission scheme.
The method of claim 27, wherein the first preamble transmission scheme differs from the second preamble transmission scheme in terms of at least one or more of:

preamble format,

subcarrier spacing (SCS) ,

bandwidth,

slot-level repetition,

a time-domain orthogonal cover code (OCC) across a respective set of slots, symbols, or ROs,

symbol-level repetition, or

any combination thereof.
The method of claim 27,

wherein the first preamble transmission scheme comprises one or more preamble sequences that are not used by the second preamble transmission scheme,

wherein the first preamble transmission scheme comprises cross-RO repetition with a time-domain orthogonal cover code (OCC) that is not used by the second preamble transmission scheme, or

any combination thereof.
A user equipment (UE) , comprising:

means for performing one or more signal reception quality measurements associated with a downlink signal on a downlink channel;

means for selecting a group of random access channel (RACH) opportunities (ROs) among a plurality of groups of ROs based on the one or more signal reception quality measurements, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class; and

means for transmitting a preamble associated with a RACH procedure on the selected group of ROs.
A base station, comprising:

means for transmitting a downlink signal on a downlink channel

means for receiving, from a UE belonging to a first UE class based on one or more signal reception quality measurements of the downlink signal at the UE, a preamble associated with a random access channel (RACH) procedure over one group among a plurality of groups of RACH opportunities (ROs) , the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class,

wherein the group of ROs over which the preamble is received is indicative of a characteristic of the one or more signal reception quality measurements
A user equipment (UE) , comprising:

a memory; and

at least one processor coupled to the memory and configured to:

perform one or more signal reception quality measurements associated with a downlink signal on a downlink channel;

select a group of random access channel (RACH) opportunities (ROs) among a plurality of groups of ROs based on the one or more signal reception quality measurements, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class; and

transmit a preamble associated with a RACH procedure on the selected group of ROs.
A base station, comprising:

a memory; and

at least one processor coupled to the memory and configured to:

transmit a downlink signal on a downlink channel; and

receive, from a UE belonging to a first UE class based on one or more signal reception quality measurements of the downlink signal at the UE, a preamble associated with a random access channel (RACH) procedure over one group among a plurality of groups of RACH opportunities (ROs) , the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class,

wherein the group of ROs over which the preamble is received is indicative of a characteristic of the one or more signal reception quality measurements.
A non-transitory computer-readable medium containing instructions stored thereon, for causing at least one processor in a user equipment (UE) to:

perform one or more signal reception quality measurements associated with a downlink signal on a downlink channel;

select a group of random access channel (RACH) opportunities (ROs) among a plurality of groups of ROs based on the one or more signal reception quality measurements, the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class; and

transmit a preamble associated with a RACH procedure on the selected group of ROs.
A non-transitory computer-readable medium containing instructions stored thereon, for causing at least one processor in a base station to:

transmit a downlink signal on a downlink channel; and

receive, from a UE belonging to a first UE class based on one or more signal reception quality measurements of the downlink signal at the UE, a preamble associated with a random access channel (RACH) procedure over one group among a plurality of groups of RACH opportunities (ROs) , the plurality of groups of ROs comprising a first group of ROs dedicated to the first UE class,

wherein the group of ROs over which the preamble is received is indicative of a characteristic of the one or more signal reception quality measurements.