Random Access Response Mapping for Two-Step Random Access Channel Procedures

Abstract

Various aspects of the present disclosure generally relate to wireless communications. In some aspects, a base station (BS) may group and selectively multiplex multiple Random Access Channel Responses (RARs) and Radio Resource Control (RRC) messages into a Message B communication along with supplemental scheduling information for other RARs to be mapped to different msgB (msgB) communications. The BS may transmit the msgB communications to one or more user equipment. Numerous other aspects are provided.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Provisional Patent Application No. 62 / 912,558, filed October 8, 2019, entitled “RANDOM ACCESS RESPONSE MAPPING FOR TWO-STEP RANDOM ACCESS CHANNEL PROCEDURE,” and U.S. Nonprovisional Patent Application No. 16 / 948,956, filed October 7, 2020, entitled “RANDOM ACCESS RESPONSE MAPPING FOR TWO-STEP RANDOM ACCESS CHANNEL PROCEDURE,” which are hereby expressly incorporated by reference.

[0002] Aspects of the present disclosure relate generally to wireless communications and to techniques and apparatus for random access response mapping for a two-step random access channel procedure. [Background technology]

[0003] Wireless communication systems have been widely deployed to provide various telecommunication services, such as telephone, video, data, messaging, and broadcast. A typical wireless communication system may utilize multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / LTE-Advanced is a set of extensions to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the 3rd Generation Partnership Project (3GPP).

[0004] A wireless communication network may include several base stations (BSs) that can support communication for several user equipments (UEs). The user equipments (UEs) may communicate with the base stations (BSs) via downlinks and uplinks. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As described in more detail herein, a BS may be referred to as a Node B, gNB, access point (AP), radio head, transmit / receive point (TRP), new radio (NR) BS, 5G Node B, etc.

[0005] The above multiple access technologies have been adopted in various telecommunication standards to provide common protocols that allow various user equipment to communicate at city, national, regional, and even global levels. New Radio (NR), sometimes referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by increasing spectral efficiency, reducing costs, improving services, utilizing new spectrum, using Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) (CP-OFDM) on the downlink (DL), CP-OFDM and / or SC-FDM (also known as Discrete Fourier Transform Spread OFDM (DFT-s-OFDM) on the uplink (UL) to better harmonize with other open standards, as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to grow, further improvements in LTE and NR technologies are needed. Preferably, these improvements should be applicable to other multiple access technologies and telecommunications standards that utilize these technologies. Summary of the Invention [Means for solving the problem]

[0006] In some aspects, a method of wireless communication implemented by a base station (BS) may include grouping and selectively multiplexing a plurality of random access channel responses (RARs) into a message B (msgB) communication and transmitting the msgB communication to one or more user equipments (UEs).

[0007] In some aspects, a method of wireless communication implemented by a UE may include receiving, from a BS, a msgB communication associated with a two-step RACH procedure between the UE and the BS, and identifying a RAR associated with the UE among a plurality of RARs multiplexed into the msgB communication and supplemental scheduling information for other RARs.

[0008] In some aspects, a BS for wireless communication may include a memory and one or more processors coupled to the memory, wherein the memory and the one or more processors may be configured to group and selectively multiplex a plurality of RARs into a msgB communication and transmit the msgB communication to one or more UEs.

[0009] In some aspects, a UE for wireless communication may include a memory and one or more processors coupled to the memory. The memory and the one or more processors may be configured to receive, from a BS, a msgB communication associated with a two-step RACH procedure between the UE and the BS, and to identify a RAR associated with the UE among multiple RARs multiplexed into the msgB communication and supplemental scheduling information for other RARs.

[0010] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication that, when executed by one or more processors of a BS, may cause the one or more processors to group and selectively multiplex multiple RARs into a msgB communication and transmit the msgB communication to one or more UEs.

[0011] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication that, when executed by one or more processors of a UE, may cause the one or more processors to receive, from a BS, a msgB communication associated with a two-step RACH procedure between the UE and the BS, and identify a RAR associated with the UE among multiple RARs multiplexed into the msgB communication, and supplemental scheduling information for other RARs.

[0012] In certain aspects, an apparatus for wireless communication may include means for grouping and selectively multiplexing a plurality of RARs into a msgB communication and means for transmitting the msgB communication to one or more UEs.

[0013] In some aspects, an apparatus for wireless communication may include means for receiving, from a BS, a msgB communication associated with a two-step RACH procedure between the device and the BS, and means for identifying a RAR associated with the device among multiple RARs multiplexed into the msgB communication and supplemental scheduling information for other RARs.

[0014] Aspects generally include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and / or processing systems, as fully described herein with reference to and as illustrated by the accompanying drawings and this specification.

[0015] The foregoing has outlined rather broadly the features and technical advantages of examples according to the present disclosure so that the detailed description that follows may be better understood. Additional features and advantages are described below. The concepts and 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. The properties of the concepts disclosed herein, both their construction and methods of operation, together with associated advantages, will be better understood from the following description when considered in conjunction with the accompanying figures. Each of the figures is provided for the purpose of illustration and explanation, and not as a definition of the limits of the claims.

[0016] So that the above-mentioned features of the present disclosure can be understood in detail, a more detailed description, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. However, since the present description may admit of other equally effective embodiments, it should be noted that the accompanying drawings illustrate only some typical embodiments of the present disclosure and therefore should not be considered as limiting its scope. The same reference numbers in different drawings may identify the same or similar elements. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram illustrating an example of a wireless communication network, in accordance with various aspects of the present disclosure. [Diagram 2] FIG. 1 is a block diagram illustrating an example of a base station (BS) communicating with a user equipment (UE) in a wireless communication network, in accordance with various aspects of the present disclosure. [Figure 3A] A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 3B] A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 3C]A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 3D] A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 3E] A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 3F] A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 3G] A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 3H] A diagram illustrating one or more examples of random access response mapping for a two-step random access channel procedure, in accordance with various aspects of the present disclosure. [Figure 4] FIG. 2 illustrates an example process performed, for example, by a BS, in accordance with various aspects of the present disclosure. [Diagram 5] 1 illustrates an example process performed, for example, by a UE, in accordance with various aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Various aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout the present disclosure. Rather, these aspects are provided so that the disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art should understand that the scope of the present disclosure encompasses any aspect of the present disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of the present disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects described herein. In addition, the scope of the present disclosure is intended to cover an apparatus or method practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure described herein. It should be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of a claim.

[0019] Several aspects of a telecommunications system are now presented with reference to various apparatus and techniques. These apparatus and techniques are described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0020] Although aspects may be described herein using terminology commonly associated with 3G and / or 4G wireless technologies, it should be noted that aspects of the present disclosure may be applied in other generation-based communication systems, such as 5G and beyond, including NR technologies.

[0021] FIG. 1 illustrates a wireless network 100 in which aspects of the disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include several 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 (UE) and may also be referred to as a base station, NR BS, Node B, gNB, 5G Node B (NB), access point, transmit / receive point (TRP), etc. 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.

[0022] 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., a radius of several kilometers) and may allow unrestricted access by UEs with a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs with an 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 also be referred to as a femto BS or a home BS. In the example shown in FIG. 1, BS 110a may be a macro BS for macro cell 102a, BS 110b may be a pico BS for pico cell 102b, and BS 110c may be a femto BS for femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB,” “base station,” “NR BS,” “gNB,” “TRP,” “AP,” “Node B,” “5G NB,” and “cell” may be used interchangeably herein.

[0023] In some aspects, the cells may not necessarily be stationary and the geographic area of ​​the cells may move according to the location of the mobile BS. In some aspects, the BSs may be interconnected to each other 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 direct physical connections, virtual networks, etc., using any suitable transport network.

[0024] The 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 the 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 a macro BS 110a and a UE 120d to facilitate communication between the BS 110a and the UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, etc.

[0025] Wireless network 100 may be a heterogeneous network including different types of BSs, e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different susceptibility to interference in wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 5-40 watts), while a pico BS, femto BS, and relay BS may have a lower transmit power level (e.g., 0.1-2 watts).

[0026] A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with each other directly or indirectly, e.g., via wireless or wireline backhaul.

[0027] The UEs 120 (e.g., 120a, 120b, 120c) may be distributed throughout the wireless network 100, and each UE may be fixed or mobile. A UE may also be referred to as an access terminal, terminal, mobile station, subscriber unit, station, etc. A UE may be a cellular phone (e.g., a smartphone), 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, a biometric sensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or satellite radio), a vehicle component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate over a wireless or wired medium.

[0028] Some UEs may be considered as machine type communication (MTC) UEs or evolved or enhanced machine type communication (eMTC) UEs. MTC UEs and eMTC UEs include, for example, a robot, a drone, a remote device, a sensor, a meter, a monitor, a location tag, etc. that may communicate with a base station, another device (e.g., a 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 the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered as Internet of Things (IoT) devices and / or may be implemented as NB-IoT (narrowband Internet of Things) devices. Some UEs may be considered as customer premises equipment (CPE). The UE 120 may be included in a housing that stores components of the UE 120, such as a processor component, a memory component, etc.

[0029] In general, any number of wireless networks may be deployed within a given geographic area. Each wireless network may support a particular RAT and may operate on one or more frequencies. The RAT may also be referred to as a radio technology, an air interface, etc. The frequencies may also be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR networks or 5G RAT networks may be deployed.

[0030] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly (e.g., without using the base station 110 as an intermediary for communicating with each other) using one or more sidelink channels. For example, the UEs 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (which may include, e.g., vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, etc.), mesh networks, etc. In this case, the UEs 120 may perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by the base station 110.

[0031] As noted above, Figure 1 is provided as an example. Other examples may differ from those described with respect to Figure 1.

[0032] 2 shows a block diagram of a design 200 of a base station 110 and a 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.

[0033] At the base station 110, the transmit processor 220 may receive data for one or more UEs from a data source 212, select one or more modulation and coding schemes (MCS) for each UE based at least in part on a channel quality indicator (CQI) 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 to all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, higher layer signaling, etc.) and provide overhead and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​the data symbols, control symbols, overhead symbols, and / or 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 OFDM, etc.) 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. The 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, synchronization signals may be generated using location coding to convey additional information.

[0034] At the UE 120, antennas 252a-252r may receive downlink signals from the base station 110 and / or other base stations and may provide received signals to demodulators (DEMODs) 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a-254r, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols and provide decoded data for the UE 120 to a data sink 260 and provide decoded control and system information to the controller / processor 280. The channel processor may determine a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), a channel quality indicator (CQI), etc. In some aspects, one or more components of the UE 120 may be included in a housing.

[0035] On the uplink, at the UE 120, the transmit processor 264 may receive and process data from the data source 262 and control information (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.) from the controller / processor 280. The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a-254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, uplink signals from the UE 120 and other UEs may be received by the antennas 234, processed by the demodulator 232, detected by a MIMO detector 236 if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0036] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other components of FIG. 2 may perform one or more techniques associated with random access response (RAR) mapping for a two-step random access channel (RACH) procedure, as described in more detail elsewhere herein. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or any other components of FIG. 2 may perform or direct the operation of, for example, process 400 of FIG. 4, process 500 of FIG. 5, and / or other processes as described herein. The memory 242 and the memory 282 may store data and program codes for the base station 110 and the UE 120, respectively. In some aspects, the memory 242 and / or the memory 282 may include a non-transitory computer-readable medium that stores one or more instructions for wireless communication. For example, the one or more instructions, when executed by one or more processors at the base station 110 and / or the UE 120, may perform or direct operation of, for example, process 400 in FIG. 4, process 500 in FIG. 5, and / or other processes as described herein. The scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0037] In some aspects, the UE 120 may include means for receiving from the BS 110 a message B (msgB) communication associated with a two-step RACH procedure between the UE 120 and the BS 110, means for identifying a RAR associated with the UE 120 among multiple RARs multiplexed into the msgB communication and supplemental scheduling information for other RARs, etc. In some aspects, such means may include one or more components of the UE 120 described in connection with FIG. 2, such as the controller / processor 280, the transmit processor 264, the TX MIMO processor 266, the MOD 254, the antennas 252, the DEMOD 254, the MIMO detector 256, the receive processor 258, etc.

[0038] In some aspects, the base station 110 may include means for grouping and selectively multiplexing multiple RARs into a msgB communication, means for transmitting the msgB communication to one or more UEs 120, etc. In some aspects, such means may include one or more components of the base station 110 described with respect to FIG. 2, such as the antennas 234, the DEMOD 232, the MIMO detector 236, the receive processor 238, the controller / processor 240, the transmit processor 220, the TX MIMO processor 230, the MOD 232, the antennas 234, etc.

[0039] As noted above, Figure 2 is given as an example. Other examples may differ from that described with respect to Figure 2.

[0040] A UE may access a wireless network by negotiating a connection with a BS included in the wireless network. During connection establishment, the UE and the BS may synchronize the connection in the downlink direction (i.e., from the BS to the UE) and in the uplink direction (i.e., from the UE to the BS).

[0041] To synchronize the connection in the downlink direction, the UE may read a synchronization signal block (SSB) that includes various synchronization signals transmitted from the BS. The synchronization signals may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a primary broadcast channel (PBCH), etc. The UE may use the PSS to determine symbol timing in the downlink direction, the SSS to determine a physical cell identifier associated with the BS, and the PBCH to determine frame timing.

[0042] To synchronize the connection in the uplink direction, the UE and the BS may perform a RACH procedure. In some aspects, the UE and the BS may perform a four-step RACH procedure. In the four-step RACH procedure, the UE and the BS may exchange four primary RACH communications. The UE may send a message 1 (msg1) communication to the BS (e.g., as defined in a 3GPP four-step RACH procedure). The msg1 communication may be a RACH preamble communication transmitted during a RACH opportunity (e.g., a specific set of time-frequency resources), the combination of which may be referred to as a RACH signature. The BS may respond to the msg1 communication with a message 2 (msg2) communication (e.g., as defined in a 3GPP four-step RACH procedure), which may be a random access response (RAR) communication. The UE may respond to the msg2 communication with a message 3 (msg3) communication (e.g., as defined in a 3GPP four-step RACH procedure), which may be a radio resource control (RRC) connection request communication. The BS may respond to the msg3 communication with a message 4 (msg4) communication (e.g., as defined in the 3GPP four-step RACH procedure), which may be a Medium Access Control (MAC) Control Element (MAC-CE) Contention Resolution Identifier communication and may include an RRCSetup command, etc.

[0043] In some cases, the four-step RACH procedure may not meet the low latency requirements of 5G / NR wireless systems. Therefore, the UE and the BS may use a two-step RACH procedure to reduce latency in synchronizing the connection in the uplink direction. In the two-step RACH procedure, the UE may combine the msg1 and msg3 communications into a communication referred to as a message A (msgA) communication (e.g., as defined in the 3GPP two-step RACH procedure). The msg1 portion of the msgA communication may be referred to as a preamble portion of the msgA communication. The msg3 portion of the msgA communication may be referred to as a payload portion of the msgA communication. The UE may transmit the msg1 and msg3 portions consecutively and prior to receiving the msg2 and msg4 communications.

[0044] The BS may receive the msgA communication and may transmit the msgB communication (e.g., as defined in the 3GPP four-step RACH procedure), which may include the msg2 and msg4 communications. The msgB communication may include a physical downlink control channel (PDCCH) portion and a physical downlink shared channel (PDSCH) portion. The PDSCH portion may carry the payload of the msgB communication, which may include a RAR directed to the UE.

[0045] The RAR may be a fallback RAR, a success RAR (with or without an associated Radio Resource Control (RRC) message), a backoff indicator, etc. A fallback RAR may be sent if the preamble portion of the msgA communication is detected and decoded but the payload portion is not. The fallback RAR may indicate to the UE to fall back to a four-step RACH procedure and may include a random access preamble identifier (RAPID) for the UE, an RAR grant, a timing advance command, and a temporary cell radio network temporary identifier (TC-RNTI) for retransmitting the payload portion of the msg3 or msgA communication.

[0046] If the preamble and payload portions are detected and decoded, a success RAR may be transmitted that may indicate to the UE to proceed with the two-step RACH procedure and may identify a contention resolution identifier, a timing advance command, and a Cell Radio Network Temporary Identifier (C-RNTI).

[0047] The UE may monitor the msgB communication during the RAR reception window. The starting point of the RAR reception window may be aligned with the first PDCCH symbol of the earliest search space for the msgB communication. If the UE does not receive either a success RAR or a fallback RAR by the expiration of the RAR reception window, the UE may retransmit the msgA communication.

[0048] In some cases, the BS may transmit a respective RAR to each of multiple UEs, where each RAR is included in a separate msgB communication. This may cause increased power consumption in the multiple UEs, since each UE may have to monitor and decode multiple msgB communications during an associated RAR reception window to receive the RAR intended for the UE. Moreover, the BS may also transmit RAR retransmissions during the RAR reception window in separate msgB communications, further increasing the amount of msgB communications that each UE may have to monitor and decode during its associated RAR reception window.

[0049] Some aspects described herein provide techniques and apparatus for RAR mapping for a two-step RACH procedure. In some aspects, a BS may multiplex multiple RARs into a single msgB communication and transmit the msgB communication to one or more UEs. This allows the BS to reduce the amount of msgB communication transmitted to the UE compared to transmitting multiple RARs in individual and / or separate msgB communications. The reduced amount of msgB communication reduces processing, memory, and power resource consumption at the UE because the UE needs to monitor and decode fewer msgB communications during the associated RAR reception window to receive the RARs.

[0050] To further reduce processing, memory, and power resource consumption at the UE, the BS may multiplex RARs of the same type and / or different types into the same msgB communication, allowing successful RARs, fallback RARs, initial RAR transmissions, and / or RAR retransmissions to be included in the same msgB communication. The BS may provide an early indication of which msgB communication will carry RARs intended for a particular UE or group of UEs, thereby further reducing processing, memory, and power resource consumption at the UE.

[0051] 3A-3H are diagrams illustrating one or more examples 300 of RAR mapping for a two-step RACH procedure, in accordance with various aspects of the present disclosure. As shown in FIG. 3A-3H, the example 300 may include communications between a BS (e.g., BS 100) and a number of UEs (e.g., UE 120), such as UE1-UEn. The BS and the number of UEs may be included in a wireless network, such as wireless network 100.

[0052] In some aspects, each of the multiple UEs may perform a RACH procedure with the BS to establish a wireless connection with the BS. The RACH procedure may include, for example, a two-step RACH procedure, a four-step RACH procedure, etc. In some aspects, a UE of the multiple UEs may initiate the two-step RACH procedure by transmitting a msgA communication to the BS. In this case, the UE may transmit a preamble portion of the msgA communication during a preamble opportunity (e.g., one or more time-frequency resources configured for RACH preamble transmission) and a payload portion of the msgA communication during a physical uplink shared channel (PUSCH) opportunity (e.g., one or more time-frequency resources configured for msgA payload transmission).

[0053] As shown in FIG. 3A and by reference numeral 302, the BS may multiplex RARs directed to multiple UEs into a msgB communication. In some aspects, the BS may multiplex RARs directed to multiple UEs into the same msgB communication. In some aspects, the BS may time-division multiplex the RARs into the msgB communication, frequency-division multiplex the RARs into the msgB communication, spatially multiplex the RARs into the msgB communication, or a combination thereof. In some aspects, the BS may multiplex a subset of the RARs directed to multiple UEs into different msgB communications. In this case, the BS may scramble the msgB communications with the same RNTI (e.g., the same msgB-RNTI and / or another type of RNTI). In some aspects, if the RAR window is long (e.g., 20 ms or more), the value of the msgB RNTI may change over time. For example, msgB_RNTI(K)=msgB_RNTI(K-1)+delta(K-1), where delta(K-1) captures the time change of msgB_RNTI from radio frame (K-1) to radio frame (K). In some cases, the BS may scramble msgB communications using the same set of msgB wireless network temporary identifiers mapped to the same random access opportunity.

[0054] In some aspects, the BS may multiplex RARs of the same type into the msgB communication, multiplex RARs of different types into the msgB communication, or a combination thereof. For example, the BS may multiplex one or more successful RARs (with or without associated RRC messages) into the msgB communication, multiplex one or more fallback RARs into the msgB communication, etc. As another example, the BS may multiplex an initial or first transmission of one or more RARs into the msgB communication (e.g., one or more initial or first transmissions of a successful RAR, a fallback RAR, etc.), multiplex a retransmission of one or more RARs into the msgB communication (e.g., one or more retransmissions of a successful RAR, a fallback RAR, etc.), etc.

[0055] 3B and 3C show various examples of RARs multiplexed into one or more msgB communications. As shown in the example shown in FIG. 3B, the BS may multiplex different subsets of RARs (e.g., RAR1-RAR5) directed to five UEs into each msgB communication. In particular, the BS may multiplex initial transmissions of RAR1, RAR2, and RAR3 (e.g., directed to UE1, UE2, and UE3, respectively) into msgB1, initial transmissions of RAR4 and RAR5 (e.g., directed to UE4 and UE5, respectively) into msgB2, and retransmissions of RAR1, RAR2, and RAR3 (e.g., directed to UE1, UE2, and UE3, respectively) into msgB3.

[0056] As further illustrated in the example shown in FIG. 3B, different types of RARs may be multiplexed into the same msgB communication. For example, msgB1 may include a successful RAR without an associated RRC message (e.g., RAR1), a successful RAR with an associated RRC message (e.g., RAR2), and a fallback RAR (e.g., RAR3). As another example, msgB2 may include a fallback RAR (e.g., RAR4) and a successful RAR with an associated RRC message (e.g., RAR5). As another example, msgB3 may include a successful RAR without an associated RRC message (e.g., RAR1), a successful RAR with an associated RRC message (e.g., RAR2), and a fallback RAR (e.g., RAR3).

[0057] 3C, the BS may multiplex different subsets of RARs (e.g., RAR1-RAR5) directed to the five UEs into each msgB communication. In particular, the BS may multiplex the initial transmissions of RAR1, RAR2, and RAR3 (e.g., directed to UE1, UE2, and UE3, respectively) into msgB1, may multiplex a retransmission of RAR1 along with the initial transmission of RAR4 (e.g., directed to UE4) into msgB2, and may include the initial transmission of RAR5 (e.g., directed to UE5) in msgB3.

[0058] As further illustrated in the example shown in FIG. 3B, different types of RARs may be multiplexed into the same msgB communication. For example, msgB1 may include a successful RAR without an associated RRC message (e.g., RAR1), a successful RAR with an associated RRC message (e.g., RAR2), and a fallback RAR (e.g., RAR3). As another example, msgB2 may include an initial transmission of a fallback RAR (e.g., RAR4) and a retransmission of a successful RAR without an associated RRC message (e.g., RAR1).

[0059] The BS may use various techniques to identify RARs that should be multiplexed into the same msgB communication. In some aspects, the BS may multiplex RARs into the same msgB communication based at least in part on the respective priorities associated with each of the RARs. For example, the BS may multiplex a high priority RAR into the same msgB communication and may transmit the msgB communication earlier in time compared to a msgB communication carrying a multiplexed RAR of relatively lower priority.

[0060] In some aspects, the BS may multiplex the RARs into the same msgB communication based at least in part on the respective payload sizes associated with the RARs to efficiently use the available space in the msgB communication. For example, the BS may be allowed to include a certain amount of bits or bytes in the payload portion of the msgB communication, and the BS may multiplex the RARs into the msgB communication such that the RARs use a majority amount of the available space in the msgB communication.

[0061] In some aspects, the BS may group RARs directed to UEs that transmitted preambles during the same preamble opportunity into one or more sets of RARs. The BS may multiplex each set of RARs into a respective msgB communication such that the transmission of the sets of RARs is ordered in time. The order of the sets of RARs may be based at least in part on the starting symbol of the respective RAR reception window associated with each of the UEs. For example, the BS may multiplex RARs directed to a first group or set of UEs having associated RAR reception windows starting on the same symbol into a first msgB communication, RARs directed to a second group or set of UEs having associated RAR reception windows starting on the same symbol into a second msgB communication, etc.

[0062] 3D and 3E illustrate various examples of grouping RARs into sets based at least in part on the starting symbol of a respective RAR reception window associated with one or more UEs. In the example illustrated in FIG. 3D, multiple UEs may transmit a RACH preamble (e.g., a preamble portion of a msgA communication in a two-step RACH procedure) during the same preamble opportunity X. A first subset of the UEs may transmit the msgA payload portion during a PUSCH opportunity Y, and a second subset of the UEs may transmit the msgA payload portion during a PUSCH opportunity Z that occurs after the PUSCH opportunity Y. In this example, the starting symbol of a first RAR reception window associated with a preamble opportunity / PUSCH opportunity combination (X,Y) may be a different symbol than the starting symbol of a second RAR reception window associated with a preamble opportunity / PUSCH opportunity combination (X,Z). Thus, the BS may multiplex the RARs directed to a first subset of UEs into a first msgB communication (X,Y) and may transmit the first msgB communication during the first RAR reception window. Additionally, the BS may multiplex the RARs directed to a second subset of UEs into a second msgB communication (X,Z) and may transmit the second msgB communication during the second RAR reception window.

[0063] In the example shown in FIG. 3E, multiple UEs may transmit RACH preambles (e.g., preamble portions of msgA communications in a two-step RACH procedure) during the same preamble opportunity X. A first subset of UEs may transmit msgA payload portions during PUSCH opportunity Y, and a second subset of UEs may transmit msgA payload portions during PUSCH opportunity Z. In this example, the starting symbol of a first RAR reception window associated with preamble opportunity / PUSCH opportunity combination (X,Y) may be the same symbol as the starting symbol of a second RAR reception window associated with preamble opportunity / PUSCH opportunity combination (X,Z). Thus, the BS may multiplex RARs directed to the first and second subsets of UEs into the same msgB communications (X,Y)&(X,Z) and may transmit the msgB communications during the RAR reception window.

[0064] 3F and by reference numeral 304, the BS may transmit a msgB communication to multiple UEs. The msgB communication may include multiple RARs multiplexed for the multiple UEs. In some aspects, the BS may transmit the msgB communication to multiple UEs if the BS multiplexes a subset of the multiple RARs into different msgB communications. The BS may transmit the msgB communication during an RAR reception window associated with each of the multiple UEs.

[0065] As described above, the UE may monitor and decode a msgB communication during an associated RAR reception window. The UE may need to decode multiple msgB communications before identifying an RAR directed to the UE, which increases processing, memory, and / or power consumption at the UE. To reduce the amount of msgB communications to be decoded by the UE during the RAR reception window, the BS may include an early indicator of the transmission timing for the msgB communication carrying the RAR directed to the UE in one or more msgB communications transmitted during the RAR reception window. In this manner, the UE may decode the msgB communication, identify an early indicator in the msgB communication (e.g., which may identify a subsequent msgB communication carrying an RAR directed to the UE), and may refrain from monitoring and decoding any intervening msgB communication that precedes the msgB communication carrying the RAR directed to the UE.

[0066] FIG. 3G illustrates an example of an early indicator of an RAR directed to a UE (or a set or group of UEs). As shown in FIG. 3G, the BS may transmit multiple msgB communications during an RAR reception window associated with one or more UEs. The RAR directed to the UE may be included in msgB3, which may be transmitted after msgB1 and msgB2 during the RAR reception window. In this example, the BS may include an early indicator in msgB1 and msgB2 that the RAR is included in msgB3. Thus, the UE may receive and decode msgB1, identify the early indicator, and refrain from receiving and decoding msgB2 based at least in part on the early indicator. If the UE lacks or is unable to decode msgB1, the UE may receive and decode msgB2, identify the early indicator, and monitor and receive msgB3 based at least in part on the early indicator.

[0067] In some aspects, the BS may include an early indicator of the transmission timing for a msgB communication carrying the RAR in a PDCCH portion of another msgB communication, in a PDSCH portion of another msgB communication, etc. For example, the early indicator may be included in a downlink control information (DCI) in the PDCCH portion of the other msgB communication, may be included in a medium access control (MAC) subheader in the PDCCH or PDSCH portion, may be included in a MAC sub-protocol data unit (PDU) in the PDCCH or PDSCH portion, etc.

[0068] In some aspects, the early indicator of the transmission timing for the msgB communication carrying the RAR may include a compressed UE identifier associated with the UE (or UEs) to which the RAR is directed. The UE may determine that the early indicator is for the UE based at least in part on the compressed UE identifier indicated in the msgB communication carrying the early indicator. The compressed UE identifier may include a RAPID associated with the UE, a most significant bit (MSB) of a C-RNTI associated with the UE, a least significant bit (LSB) of a C-RNTI associated with the UE, an MSB of an idle or inactive radio network temporary identifier (I-RNTI) associated with the UE, a LSB of an I-RNTI associated with the UE, and / or another type of compressed UE identifier.

[0069] In some aspects, the early indicator may include a timing offset between the msgB communication carrying the early indicator and the msgB communication carrying the RAR directed to the UE, where the timing offset may include a slot-level offset, a symbol-level offset, a backoff indication, or a combination thereof. The timing offset may be specified for a control resource set (CORESET) or search space associated with the msgB communication carrying the RAR directed to the UE and may be indicated relative to the msgB communication carrying the early indicator. In some aspects, the early indicator may include an index of a search space associated with the msgB communication carrying the RAR directed to the UE. Thus, the UE may identify the msgB communication carrying the RAR directed to the UE based at least in part on the timing offset and / or index of the search space.

[0070] As shown in FIG. 3H and by reference numeral 306, UE1 may receive a msgB communication from the BS and may identify an RAR associated with UE1 that is included in the msgB communication. In some aspects, UE1 may identify an RAR among multiple RARs multiplexed into the msgB communication. In some aspects, UE1 may identify an RAR based at least in part on an RAR that is scrambled using an RNTI associated with the UE and / or another type of UE identifier associated with the UE. In some aspects, other UEs in the multiple UEs may receive a msgB communication from the BS and may use similar techniques to identify associated RARs.

[0071] In some aspects, a UE (e.g., UE1 and / or another UE of the plurality of UEs) may transmit hybrid automatic repeat request (HARQ) feedback to the BS based at least in part on the msgB communication. The HARQ feedback may include an acknowledgement (ACK) if the UE is able to decode the msgB communication, or a negative ACK (NACK) if the UE is unable to decode or did not receive the msgB communication. In some aspects, the UE may transmit the HARQ feedback to the BS in a physical uplink control channel (PUCCH) communication (e.g., during, after, a two-step RACH procedure, etc.).

[0072] In some aspects, the BS may include one or more PUCCH parameters for the HARQ feedback in the associated msgB communication, in another msgB communication transmitted prior to the associated msgB communication (e.g., with an early indicator), etc. The one or more PUCCH parameters may be included in a PDCCH portion of the msgB communication, in a PDSCH portion of the msgB communication, etc. In some aspects, the UE may transmit HARQ feedback associated with the msgB communication based at least in part on the one or more PUCCH parameters.

[0073] To reduce the signaling overhead of transmitting an indication of one or more PUCCH parameters, the BS may configure one or more PUCCH parameters to include one or more common PUCCH parameters shared by multiple UEs and one or more UE-specific PUCCH parameters that are specific to a particular UE. The one or more common PUCCH parameters may include a common PUCCH power control parameter (e.g., an indication of a transmit power for a PUCCH communication carrying HARQ feedback), a PUCCH resource allocation (e.g., an indication of a common set of time-frequency resources for transmitting a PUCCH communication carrying HARQ feedback), a HARQ feedback timing indicator (e.g., an indication of the timing for transmitting HARQ feedback), etc. The one or more UE-specific PUCCH parameters may include a UE-specific PUCCH power control parameter, a PDSCH-HARQ feedback timing indicator, a UE-specific PUCCH resource allocation, a UE-specific HARQ feedback timing indicator, and / or other UE-specific parameters.

[0074] In some aspects, the one or more common PUCCH parameters may be included in the DCI of the PDCCH portion of the msgB communication, in the MAC sub-header of the PDSCH portion of the msgB communication, in the MAC sub-PDU of the PDSCH portion of the msgB communication, etc. In some aspects, the one or more UE-specific PUCCH parameters may be included in the MAC sub-header of the PDSCH portion of the msgB communication, in the MAC sub-PDU of the PDSCH portion of the msgB communication, or may be implicitly derived from the UE-specific MAC sub-header order, the UE-specific MAC sub-PDU order, a preamble sequence index, a demodulation reference signal (DMRS) resource index, a PUSCH resource unit index, etc.

[0075] In this manner, the BS may multiplex multiple RARs into a single msgB communication and transmit the msgB communication to one or more of the multiple UEs. This allows the BS to reduce the amount of msgB communication transmitted to the UE compared to transmitting multiple RARs in individual and / or separate msgB communications. The reduced amount of msgB communications reduces processing, memory, and power resource consumption at the UE because the UE needs to monitor and decode fewer msgB communications during the associated RAR reception window to receive the RARs. Furthermore, the BS may further reduce processing, memory, and power resource consumption at the UE by multiplexing the same type of RARs and / or different types of RARs into the same msgB communication, which may allow successful RARs, fallback RARs, initial RAR transmissions, and / or RAR retransmissions to be included in the same msgB communication. The BS may provide an early indication of which msgB communications will carry RARs directed to a particular UE or group of UEs, thereby further reducing processing, memory, and power resource consumption at the UE.

[0076] As noted above, Figures 3A-3H are provided as one or more examples. Other examples may differ from those described with respect to Figures 3A-3H.

[0077] 4 illustrates an example process 400, performed, for example, by a BS, in accordance with various aspects of the present disclosure. The example process 400 is an example in which a BS (e.g., BS 110) performs operations associated with RAR mapping for a two-step RACH procedure.

[0078] 4, in some aspects, process 400 may include grouping and selectively multiplexing a plurality of RARs into a msgB communication (block 410). For example, the BS (e.g., using transmit processor 220, receive processor 238, controller / processor 240, memory 242, etc.) may group and selectively multiplex a plurality of RARs into a msgB communication as described above.

[0079] 4, in some aspects, process 400 may include transmitting a msgB communication to one or more UEs (block 420). For example, the BS (e.g., using transmit processor 220, receive processor 238, controller / processor 240, memory 242, etc.) may transmit the msgB communication to one or more UEs as described above.

[0080] Process 400 may include additional aspects, such as any single aspect or any combination of aspects described below and / or with respect to one or more other processes described elsewhere herein.

[0081] In a first aspect, grouping and selectively multiplexing a plurality of RARs into a msgB communication includes multiplexing a plurality of RARs and supplemental scheduling information for other RARs into a plurality of msgB communications, where the msgB communication is included in the plurality of msgB communications, and the plurality of msgB communications are time division multiplexed. In a second aspect, alone or in combination with the first aspect, the process 400 includes scrambling a plurality of msgB communications using the same msgB radio network temporary identifier or the same set of msgB radio network temporary identifiers mapped to the same random access opportunity (RO). In a third aspect, alone or in combination with one or more of the first and second aspects, the plurality of RARs includes at least one of one or more fallback RARs, one or more successful RARs with associated RRC messages, or one or more successful RARs without RRC messages.

[0082] In a fourth aspect, alone or in combination with one or more of the first to third aspects, the multiple RARs include at least one of an initial transmission of one or more of the multiple RARs or a retransmission of one or more of the multiple RARs. In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, multiplexing the multiple RARs into the msgB communication includes multiplexing the multiple RARs into the msgB communication based at least in part on at least one of a starting symbol of a respective RAR reception window associated with each of one or more UEs sharing a same random access opportunity, a respective priority associated with each of the multiple RARs, a respective Quality of Service (QoS) class associated with each of the multiple RARs, or a respective payload size of each of the multiple RARs.

[0083] In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the process 400 includes transmitting, to one or more UEs, an indication of transmit timing for the msgB communication. In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the indication of transmit timing for the msgB communication is included in another msgB communication, and transmitting the indication of transmit timing for the msgB communication includes transmitting the another msgB communication prior to transmitting the msgB communication.

[0084] In an eighth aspect, alone or in combination with one or more of the first to seventh aspects, the indication of transmission timing for the msgB communication is included in at least one of a DCI of another msgB communication, a MAC sub-header of the another msgB communication, or a MAC sub-protocol data unit of the another msgB communication. In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, the indication of transmission timing for the msgB communication includes at least one of a respective compressed UE identifier associated with each of the one or more UEs, a timing offset of a control resource set or search space associated with the msgB communication relative to the another msgB communication, or an index of a search space associated with the msgB communication.

[0085] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, each compressed UE identifier associated with each of the one or more UEs includes a random access preamble identifier, an MSB of the C-RNTI, an LSB of the C-RNTI, an MSB of the I-RNTI, or an LSB of the I-RNTI. In an eleventh aspect, alone or in combination with one or more of the first to tenth aspects, the msgB communication identifies one or more PUCCH parameters for HARQ feedback associated with the msgB communication, the one or more PUCCH parameters including at least one of one or more common PUCCH parameters or one or more UE-specific PUCCH parameters.

[0086] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, the one or more common PUCCH parameters include at least one of a PUCCH power control parameter, a PUCCH resource allocation, a PDSCH-HARQ feedback timing indicator, or a HARQ feedback timing indicator. In a thirteenth aspect, alone or in combination with one or more of the first to twelfth aspects, the one or more common PUCCH parameters are included in at least one of a DCI included in a PDCCH portion of the msgB communication, a common MAC sub-header included in a PDSCH portion of the msgB communication, or a common MAC sub-PDU included in the PDSCH portion of the msgB communication, and the one or more UE-specific PUCCH parameters are included in at least one of a UE-specific MAC sub-header included in a PDSCH portion of the msgB communication or a UE-specific MAC sub-PDU included in the PDSCH portion of the msgB communication. The UE-specific PUCCH parameters may also be derived from an implicit indication based on the UE-specific MAC sub-header order, the UE-specific MAC sub-PDU order, the preamble sequence index, the DMRS resource index or the PUSCH resource unit index used by the UE in the two-step random access procedure.

[0087] In a fourteenth aspect, alone or in combination with one or more of the first to twelfth aspects, the process 400 further includes sending to one or more UEs an indication of transmission timing for the msgB communication among supplemental scheduling information for other RARs to be mapped to different msgB communications.

[0088] 4 illustrates example blocks of process 400, in some aspects process 400 may include additional blocks, fewer blocks, different blocks, or blocks ordered differently than those illustrated in FIG 4. Additionally or alternatively, two or more of the blocks of process 400 may be performed in parallel.

[0089] 5 illustrates an example process 500, performed, for example, by a UE, in accordance with various aspects of the present disclosure. The example process 500 is an example in which a UE (e.g., UE 120) performs operations associated with RAR mapping for a two-step RACH procedure.

[0090] 5, in some aspects, process 500 may include receiving, from the BS, a msgB communication associated with a two-step RACH procedure between the UE and the BS (block 510). For example, the UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282, etc.) may receive, from the BS, a msgB communication associated with a two-step RACH procedure between the UE and the BS, as described above.

[0091] 5, in some aspects, the process 500 may include identifying a RAR associated with the UE among the multiple RARs multiplexed into the msgB communication and supplemental scheduling information for the other RARs (block 520). For example, the UE (e.g., using the receive processor 258, transmit processor 264, controller / processor 280, memory 282, etc.) may identify a RAR associated with the UE among the multiple RARs multiplexed into the msgB communication and supplemental scheduling information for the other RARs, as described above.

[0092] Process 500 may include additional aspects, such as any single aspect or any combination of aspects described below and / or with respect to one or more other processes described elsewhere herein.

[0093] In a first aspect, the multiple RARs include at least one of one or more fallback RARs, one or more successful RARs with associated RRC messages, or one or more successful RARs without RRC messages. In a second aspect, alone or in combination with the first aspect, the multiple RARs include at least one of an initial transmission of one or more RARs of the multiple RARs or a retransmission of one or more RARs of the multiple RARs. In a third aspect, alone or in combination with one or more of the first and second aspects, the process 500 includes receiving an indication of a transmission timing for a msgB communication from the BS and identifying the msgB communication based at least in part on the indication of a transmission timing for the msgB communication in the supplemental scheduling information multiplexed with the RARs.

[0094] In a fourth aspect, alone or in combination with one or more of the first through third aspects, the process 500 includes receiving an indication of transmit timing for the msgB communication in a separate msgB communication transmitted prior to the msgB communication. In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the process 500 includes identifying an indication of transmit timing for the msgB communication in at least one of a DCI of the separate msgB communication, a MAC sub-header of the separate msgB communication, or a MAC sub-protocol data unit of the separate msgB communication.

[0095] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, the indication of transmission timing for the msgB communication includes at least one of a respective compressed UE identifier associated with each of one or more UEs, a timing offset of a control resource set or search space associated with the msgB communication relative to another msgB communication, or an index of a search space associated with the msgB communication.

[0096] In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the respective compressed UE identifiers associated with each of the one or more UEs include a random access preamble identifier, an MSB of the C-RNTI, an LSB of the C-RNTI, an MSB of the I-RNTI, or an LSB of the I-RNTI, and the timing offset includes at least one of a slot level offset, a symbol level offset, or a backoff indicator. In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the process 500 includes identifying one or more PUCCH parameters for HARQ feedback and transmitting HARQ feedback associated with the msgB communication to the BS based at least in part on the one or more PUCCH parameters.

[0097] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, the one or more PUCCH parameters include at least one of one or more common PUCCH parameters or one or more UE-specific PUCCH parameters.

[0098] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, the one or more PUCCH parameters include at least one of a PUCCH power control parameter, a PUCCH resource allocation, a PDSCH-HARQ feedback timing indicator, or a HARQ feedback timing indicator. In an eleventh aspect, alone or in combination with one or more of the first to tenth aspects, the one or more common PUCCH parameters are included in at least one of a DCI included in a PDCCH portion of the msgB communication, a common MAC sub-header included in a PDSCH portion of the msgB communication, or a common MAC sub-PDU included in the PDSCH portion of the msgB communication, and the one or more UE-specific PUCCH parameters are included in at least one of a UE-specific MAC sub-header included in a PDSCH portion of the msgB communication or a UE-specific MAC sub-PDU included in the PDSCH portion of the msgB communication. The UE-specific PUCCH parameters may be derived from an implicit indication based on the MAC sub-header order, the MAC sub-PDU order, the preamble sequence index, the DMRS resource index and the PUSCH resource unit index used by the UE in the two-step random access procedure.

[0099] 5 illustrates example blocks of process 500, in some aspects process 500 may include additional blocks, fewer blocks, different blocks, or blocks ordered differently than the blocks illustrated in FIG 5. Additionally or alternatively, two or more of the blocks of process 500 may be performed in parallel.

[0100] The above disclosure provides illustration and description, and is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the embodiments.

[0101] As used herein, the term "component" is intended to be broadly interpreted 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.

[0102] As used herein, "meeting a threshold" can 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, etc., depending on the context.

[0103] It will be apparent that the systems and / or methods described herein may be implemented in various forms of hardware, firmware, and / or a combination of hardware and software. The actual dedicated 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 have been described herein without reference to specific software code. It will be understood that software and hardware can be designed to implement the systems and / or methods based at least in part on the description herein.

[0104] Although certain combinations of features are recited in the claims and / or disclosed herein, these combinations do not limit the disclosure of the various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed herein. Although each dependent claim listed below may directly depend on only one claim, the disclosure of the various aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to a list of "at least one 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 include a, b, c, ab, ac, bc, and abc, as well as any combination having multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other order of a, b, and c).

[0105] No element, act, or instruction used herein should be deemed critical or essential unless expressly 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." Additionally, as used herein, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.) and may be used interchangeably with "one or more." When only one item is intended, the phrase "only one" or similar language is used. Also, as used herein, terms such as "has," "have," "having," and the like are intended to be open-ended terms. Additionally, the phrase "based on" is intended to mean "based at least in part on," unless otherwise specified. [Explanation of symbols]

[0106] 100 Wireless Network 102a Macro Cell 102b Picocell 102c Femtocell 110 BS, base station 110a BS, Macro BS 110b BS 110c BS 110d BS, relay station 120UE 120a UE 120b UE 120c UE 120d UE 120e UE 130 Network Controller 212 Data Source 220 Transmit Processor 230 Transmit (TX) Multiple Input Multiple Output (MIMO) Processor 232 Modulator (MOD), Demodulator 234 Antenna 236 MIMO Detector 238 Receive Processor 239 Data Sink 240 Controllers / Processors 242 Memory 244 Communication Unit 246 Scheduler 252 Antenna 254 Demodulator (DEMOD), Modulator 256 MIMO detector 258 Receive Processor 260 Data Sink 262 Data Sources 264 Transmit Processor 266 TX MIMO Processor 280 Controller / Processor 282 Memory 290 Controller / Processor 292 Memory 294 Communication Unit

Claims

1. A method of wireless communication implemented by a base station (BS), comprising: multiplexing a plurality of random access channel responses (RARs) into a message B (msgB) communication; and transmitting the msgB communication to one or more user equipments (UEs); The step of multiplexing the plurality of RARs into the msgB communication includes: The plurality of RARs, a starting symbol of a respective RAR reception window associated with each of the one or more UEs sharing the same random access opportunity; a respective priority associated with each of the plurality of RARs; and a respective Quality of Service (QoS) class associated with each of the plurality of RARs; based on at least one of:

2. The step of multiplexing the plurality of RARs into the msgB communication includes: grouping and multiplexing the plurality of RARs and supplemental scheduling information for other RARs into a plurality of msgB communications, the msgB communication is included in the plurality of msgB communications, The method of claim 1 , comprising the step of: the multiple msgB communications being time division multiplexed.

3. 3. The method of claim 2, further comprising scrambling the multiple msgB communications using the same msgB radio network temporary identifier or the same set of msgB radio network temporary identifiers mapped to the same random access opportunity (RO).

4. The method of claim 2, further comprising: transmitting, to the one or more UEs, an indication of a transmission timing for the msgB communication in the supplemental scheduling information for another RAR to be mapped to a different msgB communication.

5. The plurality of RARs are one or more fallback RARs, One or more successful RARs with associated Radio Resource Control (RRC) messages; and One or more successful RARs without an RRC message, At least one of or The plurality of RARs are an initial transmission of one or more of said plurality of RARs; and retransmission of one or more of said plurality of RARs; At least one of The method of claim 1.

6. sending, to the one or more UEs, an indication of a transmission timing for the msgB communication in supplemental scheduling information for another RAR to be mapped to a different msgB communication; the indication of the transmission timing for the msgB communication is included in a separate msgB communication; transmitting the indication of the transmission timing for the msgB communication includes transmitting the separate msgB communication prior to transmitting the msgB communication; The indication of the transmission timing for the msgB communication is Downlink control information of said other msgB communication; a medium access control (MAC) subheader for said other msgB communication; and a MAC sub-protocol data unit of the other msgB communication, or The indication of the transmission timing for the msgB communication is a respective condensed UE identifier associated with each of the one or more UEs; a timing offset of a control resource set or search space associated with the msgB communication relative to the other msgB communication; and an index of the search space associated with the msgB communication; The respective condensed UE identifiers associated with each of the one or more UEs include: A random access preamble identifier, The most significant bit (MSB) of the Cell Radio Network Temporary Identifier (C-RNTI), The least significant bit (LSB) of the C-RNTI; The most significant bits of the Implicit Radio Network Temporary Identifier (I-RNTI), or the LSB of the I-RNTI; The timing offset is Slot level offset, Symbol-level offset, and a backoff indicator; The method of claim 1.

7. the msgB communication identifies one or more physical uplink control channel (PUCCH) parameters for hybrid automatic repeat request (HARQ) feedback associated with the msgB communication; The one or more PUCCH parameters are one or more common PUCCH parameters, and one or more UE specific PUCCH parameters; The one or more PUCCH parameters PUCCH power control parameters, PDSCH-HARQ feedback timing indicator, PUCCH resource allocation, and a HARQ feedback timing indicator; or The one or more common PUCCH parameters: downlink control information included in a physical downlink control channel portion of said msgB communication; a common medium access control (MAC) subheader included in a physical downlink shared channel (PDSCH) portion of the msgB communication; and a common MAC sub-protocol data unit (PDU) included in the PDSCH portion of the msgB communication; The one or more UE specific PUCCH parameters: a UE-specific MAC subheader included in the PDSCH portion of the msgB communication; a UE-specific MAC sub-PDU included in the PDSCH portion of the msgB communication; and an implicit indication based on an order of a UE-specific MAC sub-header or a UE-specific MAC sub-PDU, a preamble sequence index, a demodulation reference signal (DMRS) resource index, or a physical uplink shared channel (PUSCH) resource unit index used by the UE in a two-step random access procedure; Included in at least one of The method of claim 1.

8. 1. A method of wireless communication implemented by a user equipment (UE), comprising: receiving, from a base station (BS), a message B (msgB) communication associated with a two-step random access channel (RACH) procedure between the UE and the BS; and identifying a Random Access Channel Response (RAR) associated with the UE among a plurality of RARs multiplexed into the msgB communication, and supplemental scheduling information for other RARs; The plurality of RARs the starting symbol of a respective RAR reception window associated with each of one or more UEs sharing the same random access opportunity; a respective priority associated with each of said plurality of RARs; a respective Quality of Service (QoS) class associated with each of the plurality of RARs; and a respective payload size of each of said plurality of RARs; the msgB communication is multiplexed into the msgB communication based on at least one of

9. The plurality of RARs are one or more fallback RARs, One or more successful RARs with associated Radio Resource Control (RRC) messages; and One or more successful RARs without an RRC message, At least one of or The plurality of RARs are an initial transmission of one or more of said plurality of RARs; and retransmission of one or more of said plurality of RARs; At least one of The method of claim 8.

10. receiving a transmission timing indication for the msgB communication from the BS; and identifying the msgB communication based at least in part on the indication of the transmission timing for the msgB communication in the supplemental scheduling information multiplexed in a RAR; receiving the indication of the transmission timing for the msgB communication includes receiving the indication of the transmission timing for the msgB communication in a separate msgB communication transmitted prior to the msgB communication; The method further comprising: Downlink control information of said other msgB communication; a medium access control (MAC) subheader for said other msgB communication; and a MAC sub-protocol data unit of said another msgB communication; and further comprising identifying among at least one of: or The indication of the transmission timing for the msgB communication is a respective condensed UE identifier associated with each of the one or more UEs; a timing offset of a control resource set or search space associated with the msgB communication relative to the other msgB communication; and an index of the search space associated with the msgB communication; The respective condensed UE identifiers associated with each of the one or more UEs include: A random access preamble identifier, The most significant bit (MSB) of the Cell Radio Network Temporary Identifier (C-RNTI), The least significant bit (LSB) of the C-RNTI; The most significant bits of the idle or inactive radio network temporary identifier (I-RNTI), or the LSB of the I-RNTI; The timing offset is Slot level offset, Symbol-level offset, and a backoff indicator; The method of claim 8.

11. identifying one or more physical uplink control channel (PUCCH) parameters for hybrid automatic repeat request (HARQ) feedback; and transmitting HARQ feedback associated with the msgB communication to the BS based at least in part on the one or more PUCCH parameters.

12. The one or more PUCCH parameters PUCCH power control parameters, PDSCH-HARQ feedback timing indicator, PUCCH resource allocation, and a HARQ feedback timing indicator; or The one or more PUCCH parameters one or more common PUCCH parameters, and one or more UE specific PUCCH parameters; The one or more common PUCCH parameters: downlink control information included in a physical downlink control channel portion of said msgB communication; a common medium access control (MAC) subheader included in a physical downlink shared channel (PDSCH) portion of the msgB communication; and a common MAC sub-protocol data unit (PDU) included in the PDSCH portion of the msgB communication; The one or more UE specific PUCCH parameters: a UE-specific MAC subheader included in the PDSCH portion of the msgB communication; a UE-specific MAC sub-PDU included in the PDSCH portion of the msgB communication; and an implicit indication based on at least one of a UE-specific MAC sub-header or a UE-specific MAC sub-PDU order, a preamble sequence index, a demodulation reference signal (DMRS) resource index, or a physical uplink shared channel (PUSCH) resource unit index used by the UE in a two-step random access procedure; The method of claim 11.

13. A base station (BS) for wireless communication, comprising means for performing the method according to any one of claims 1 to 7.

14. A user equipment (UE) for wireless communication comprising means for performing the method according to any one of claims 8 to 12.

15. A computer program comprising instructions which, when executed by a processor, cause the processor to carry out a method according to any one of claims 1 to 12.

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