Configurable mode of response to random access messages

Abstract

A configurable mode of response to random access messages. Certain aspects of the present disclosure provide techniques for configurable modes of response to random access messages. A method, which may be performed by a user equipment (UE), includes receiving, from a base station (BS), an indication that the BS operates according to a first mode in which the BS unicast a RACH response during a two-step RACH procedure or a second mode in which the BS multicast a RACH response. The RACH response comprises the PDCCH and the PDSCH. The UE transmits a RACH message including a preamble and a payload to the BS. The UE monitors and decodes the PDCCH of the RACH response based on the indicated first mode or the second mode. The UE decodes the PDSCH of the RACH response based on the indicated first mode or second mode and transmits feedback to the BS.

Description

[0001] This application is a divisional application of a patent application with an international application date of August 4, 2020, an international application number of PCT / CN2020 / 106775, a Chinese application number of 202080056669.6, and an invention name of “Configurable mode of response to random access messages”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of and priority to International Patent Cooperation Treaty Application No. PCT / CN2019 / 101138, filed on August 16, 2019, which is hereby assigned to the assignee of this application and is hereby expressly incorporated herein by reference as if fully set forth below and for all applicable purposes. background

[0005] Public domain

[0006] Aspects of the present disclosure relate to wireless communications and, more particularly, to techniques for configurable modes of responses to random access messages.

[0007] Related technical description

[0008] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, etc. These wireless communication systems may employ 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 systems include Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, 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, and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, to name just a few.

[0009] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is an enhancement set of the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards using OFDMA with cyclic prefix (CP) on downlink (DL) and uplink (UL). To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0010] However, as the demand for mobile broadband access continues to grow, there is a need for further improvements to NR and LTE technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies. Overview

[0012] The systems, methods, and devices of the present disclosure each have several aspects, no single aspect of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed in the appended claims, some features will now be briefly discussed. After considering this discussion, and especially after reading the section entitled "Detailed Description," it will be understood how the features of the present disclosure provide, including improved random access procedures.

[0013] Certain aspects provide a method for wireless communications by a base station (BS). The method generally includes determining to operate according to a first mode or a second mode in which the BS unicasts a downlink random access channel (RACH) response message during a two-step RACH procedure, and in which the BS multicasts a downlink RACH response message during the two-step RACH procedure, the downlink RACH response message transmission including a physical downlink control channel (PDCCH) transmission and a physical downlink shared channel (PDSCH) transmission. The method generally includes providing an indication of the determined first mode or second mode to at least one user equipment (UE).

[0014] Certain aspects provide a method for wireless communication by a user equipment (UE). The method generally includes: receiving an indication from a BS that the BS operates according to a first mode or a second mode, in which the BS unicasts a downlink RACH response message during a two-step RACH procedure, and in which the BS multicasts a downlink RACH response message during the two-step RACH procedure. The downlink RACH response message transmission includes a PDCCH transmission and a PDSCH transmission. The method generally includes: sending an uplink RACH message including a RACH preamble and a RACH payload to the BS. The method generally includes: monitoring and decoding a PDCCH transmission of a downlink RACH response message transmission from the BS based on the indicated first mode or the second mode. The method generally includes: decoding a PDSCH transmission of the downlink RACH response message transmission based on the indicated first mode or the second mode and sending a hybrid automatic repeat request (HARQ) feedback to the BS.

[0015] Aspects of the present disclosure provide apparatuses, devices, processors, and computer-readable media for performing the methods described herein.

[0016] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are only indicative of several of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to understand in detail the manner in which the above-stated features of the present disclosure are used, a more particular description of the content briefly summarized above may be made with reference to various aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only certain typical aspects of the present disclosure and are not to be considered limiting of its scope, as the description may admit to other equally effective aspects.

[0019] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0020] Figure 2 is a block diagram conceptually illustrating designs of example base stations (BSs) and user equipment (UEs) in accordance with certain aspects of the present disclosure.

[0021] Figure 3 is an example frame format for certain wireless communication systems (e.g., New Radio (NR)) in accordance with certain aspects of the present disclosure.

[0022] Figure 4 is a timing diagram illustrating an example four-step random access channel (RACH) procedure in accordance with certain aspects of the present disclosure.

[0023] Figure 5 is a timing diagram illustrating an example two-step RACH procedure in accordance with certain aspects of the present disclosure.

[0024] Figure 6 is a timing diagram illustrating an example two-step RACH procedure in accordance with certain aspects of the present disclosure.

[0025] Fig. 7A Illustrated is a channel structure for MSG A in accordance with certain aspects of the present disclosure.

[0026] Figure 7B Transmission opportunities for MSG A are illustrated in accordance with certain aspects of the present disclosure.

[0027] Figure 8 is a table illustrating MSG A content for unicast mode in accordance with certain aspects of the present disclosure.

[0028] Fig. 9 is a table illustrating MSG A content for multicast mode in accordance with certain aspects of the present disclosure.

[0029] Fig.10 is a flow diagram illustrating example operations for wireless communications by a BS in accordance with certain aspects of the present disclosure.

[0030] Fig.11 is a flow diagram illustrating example operations for wireless communications by a BS in accordance with certain aspects of the present disclosure.

[0031] Fig.12 is a flow diagram illustrating example operations for wireless communications by a UE in accordance with certain aspects of the present disclosure.

[0032] Fig.13 is another flow diagram illustrating example operations for wireless communications by a UE in accordance with certain aspects of the present disclosure.

[0033] Fig.14 Illustrated are communications devices that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

[0034] Fig.15 Illustrated are communications devices that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

[0035] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized in other aspects without specific recitation. Detailed Description

[0037] Various aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for configurable modes of responses to random access messages. In a two-step random access channel (RACH) procedure, a user equipment (UE) sends a RACH message (e.g., referred to as MSG A) including a RACH preamble and a RACH payload to a base station (BS). The BS responds with a RACH response message (MSGB) transmission including a physical downlink control channel (PDCCH) transmission and a physical downlink shared channel (PDSCH) transmission. Unicast RACH response messages allow the BS to send a large payload to the UE. However, multicast RACH response messages reduce the complexity of blind decoding and allow the RACH response message to carry multiple small payloads for multiple UEs.

[0038] Various aspects of the present disclosure provide configurable modes for RACH response messages. For example, the BS may determine whether to use a unicast mode or a multicast mode to send the RACH response message based on various parameters such as system load, cell coverage, and / or resource availability. The BS may indicate the mode to the UE, so the UE may monitor / decode the RACH response message depending on the indicated mode. In addition, the content of the RACH response message may be based on whether the RACH preamble and / or RACH payload is received, and based on the radio resource control (RRC) state of the UE.

[0039] The following description provides an example of a configurable mode of response to a random access message in a communication system, without limiting the scope, applicability, or example set forth in the claims. Changes may be made to the functions and arrangements of the elements discussed without departing from the scope of the present disclosure. Various examples may appropriately omit, replace, or add various procedures or components. For example, the described method may be performed in an order different from the order described, and various steps may be added, omitted, or combined. Moreover, the features described with reference to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functionalities, or structures and functionalities as supplements to the various aspects of the present disclosure set forth herein or in addition. It should be understood that any aspect of the present disclosure disclosed herein may be implemented by one or more elements of the claims. The wording "exemplary" is used herein to mean "used as an example, instance, or explanation". Any aspect described as "exemplary" herein is not necessarily to be interpreted as superior to or superior to other aspects.

[0040] In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a specific radio access technology (RAT) and may operate on one or more frequencies. RAT may also be referred to as radio technology, air interface, etc. Frequency may also be referred to as carrier, subcarrier, frequency channel, frequency modulation, subband, 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, a 5G NR RAT network may be deployed.

[0041] The techniques described herein can be used for various wireless networks and radio technologies. Although various aspects may be described herein using terms typically associated with 3G, 4G, and / or new radio (e.g., 5G NR) wireless technologies, various aspects of the present disclosure may be applied in communication systems based on other generations.

[0042] NR access can support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth, millimeter wave mmW, massive machine type communication MTC (mMTC) targeting non-backward compatible MTC technology, and / or mission critical services targeting ultra-reliable low latency communication (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet corresponding quality of service (QoS) requirements. In addition, these services can coexist in the same subframe.

[0043] The electromagnetic spectrum is typically subdivided into various classes, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz–7.125 GHz) and FR2 (24.25 GHz–52.6 GHz). Frequencies between FR1 and FR2 are typically referred to as mid-band frequencies. Although a portion of FR1 is greater than 6 GHz, FR1 is typically (interchangeably) referred to as the “sub-6 GHz band” in various documents and articles. Similar naming issues sometimes arise regarding FR2, which is typically (interchangeably) referred to as the millimeter wave band in various documents and articles, although it is different from the extremely high frequency (EHF) band (30 GHz–300 GHz) identified as the “millimeter wave” band by the International Telecommunication Union (ITU).

[0044] In view of the above aspects, unless otherwise specifically stated, it should be understood that if used in this article, the term "sub-6 GHz" and the like can broadly represent frequencies that can be less than 6 GHz, can be within FR1, or can include mid-band frequencies. In addition, unless otherwise specifically stated, it should be understood that if used in this article, the term "millimeter wave" and the like can broadly represent frequencies that can include mid-band frequencies, can be within FR2, or can be within the EHF band.

[0045] NR supports beamforming and the beam direction can be dynamically configured. MIMO transmission with precoding can also be supported. MIMO configuration in DL can support up to 8 transmit antennas (multi-layer DL transmission with up to 8 streams) and up to 2 streams per UE. Multi-layer transmission with up to 2 streams per UE can be supported. Aggregation of multiple cells can be supported using up to 8 serving cells.

[0046] Figure 1 An example wireless communication network 100 is illustrated in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a NR system (e.g., a 5G NR network). Figure 1As shown in , the wireless communication network 100 may be in communication with a core network 132. The core network 132 may be in communication with one or more base stations (BSs) 110 110a-z (also each individually referred to herein as BS 110 or collectively referred to herein as BS 110) and / or user equipments (UEs) 120a-y (also each individually referred to herein as UE 120 or collectively referred to herein as UE 120) in the wireless communication network 100 via one or more interfaces.

[0047] BS 110 may provide communication coverage for a particular geographic area (sometimes referred to as a "cell"), which may be stationary or mobile depending on the location of mobile BS 110. In some examples, BS 110 may be interconnected to each other and / or to one or more other BSs or network nodes (not shown) in wireless communication network 100 via various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.) using any suitable transport network. Figure 1 In the example shown in FIG. 1 , BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. The BS may support one or more cells. BS 110 communicates with UE 120 in wireless communication network 100. UE 120 (e.g., 120x, 120y, etc.) may be dispersed throughout wireless communication network 100, and each UE 120 may be stationary or mobile.

[0048] According to certain aspects, BS 110 and UE 120 may be configured for two-step RACH with a configurable mode for RACH response messages. Figure 1 As shown in FIG. 1 , BS 110a includes RACH manager 112. According to aspects of the present disclosure, RACH manager 112 may be configured for two-step RACH with a configurable mode for RACH response messages. Figure 1 As shown in FIG. 1 , UE 120a includes RACH manager 122. According to aspects of the present disclosure, RACH manager 122 may be configured for two-step RACH with configurable modes for RACH response messages.

[0049] The wireless communication network 100 may also include a relay station (e.g., relay station 110r) (also referred to as a relay, etc.), which receives transmissions of data and / or other information from an upstream station (e.g., BS110a or UE 120r) and sends transmissions of data and / or other information to a downstream station (e.g., UE 120 or BS110), or which relays transmissions between UEs 120 to facilitate communication between the devices.

[0050] A network controller 130 may couple to a set of BSs 110 and provide coordination and control for the BSs 110. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with each other (eg, directly or indirectly) via a wireless or wired backhaul.

[0051] Figure 2 1 and 120a (eg, in a BS 110a and a UE 120a) that can be used to implement various aspects of the present disclosure are illustrated. Figure 1 Example components of the wireless communication network 100).

[0052] At BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller / processor 240. The control information may be for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a PDCCH, a group common PDCCH (GC PDCCH), etc. The data may be for a PDSCH, etc. The processor 220 may process (e.g., encode and symbol map) the data and the control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols (such as for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a channel state information reference signal (CSI-RS)). A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, and / or reference symbols, where applicable, and may provide an output symbol stream to modulators (MODs) 232a-232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The downlink signals from modulators 232a-232t may be transmitted via antennas 234a-234t, respectively.

[0053] At UE 120a, antennas 252a-252r may receive downlink signals from BS 110a and may provide received signals to demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 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 demodulators 254a-254r, perform MIMO detection on the received symbols where applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to a data sink 260, and provide decoded control information to a controller / processor 280.

[0054] On the uplink, at the UE 120a, the transmit processor 264 may receive and process data from a data source 262 (e.g., for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 280 (e.g., for a physical uplink control channel (PUCCH)). The transmit processor 264 may also generate reference symbols for reference signals (e.g., a sounding reference signal (SRS)). The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266, if applicable, further processed by a modulator in a transceiver 254a-254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signal from the UE 120a may be received by the antenna 234, processed by the modulator 232, detected by the MIMO detector 236, if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120a. Receive processor 238 may provide decoded data to data sink 239 and decoded control information to controller / processor 240 .

[0055] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively.A scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0056] The controller / processor 280 and / or other processors and modules at the UE 120a may perform or direct the execution of processes for the techniques described herein. Figure 2 As shown in FIG. 1 , the controller / processor 240 of the BS 110a has a RACH manager 241 that can be configured to configure RACH response messages for a two-step RACH procedure in accordance with various aspects described herein. Figure 2 As shown in FIG. 1 , the controller / processor 280 of the UE 120a has a RACH manager 241 that can be configured to configure a configurable RACH response message for a two-step RACH procedure in accordance with various aspects described herein. Although shown at the controller / processor, other components of the UE 120a and the BS 110a can also be used to perform the operations described herein.

[0057] NR can utilize orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP) on uplink and downlink. NR can support half-duplex operation using time division duplex (TDD). OFDM and single carrier frequency division multiplexing (SC-FDM) divide the system bandwidth into multiple orthogonal subcarriers, which are also often called frequency modulation, frequency slot, etc. Each subcarrier can be modulated with data. Modulation code elements can be sent in the frequency domain under OFDM and in the time domain under SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers can depend on the system bandwidth. The minimum resource allocation (so-called resource block (RB)) can be 12 consecutive subcarriers. The system bandwidth can also be divided into subbands. For example, one subband can cover multiple RBs. NR can support a base subcarrier spacing (SCS) of 15KHz, and other SCSs (e.g., 30kHz, 60kHz, 120kHz, 240kHz, etc.) can be defined relative to the base SCS.

[0058] Figure 3 300 is a diagram showing an example of a frame format for NR. The transmission timeline of each of the downlink and uplink may be divided into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be divided into 10 subframes with indices 0 to 9, each subframe being 1 ms. Each subframe may include a variable number of slots (e.g., 1, 2, 4, 8, 16, ... slots), depending on the SCS. Each slot may include a variable number of symbol periods (e.g., 7, 12, or 14 symbols), depending on the SCS. An index may be assigned to the symbol period in each slot. A mini slot (which may be referred to as a subslot structure) refers to a transmission time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols). Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission, and the link direction for each subframe may be dynamically switched. The link direction may be based on the slot format. Each time slot may include DL / UL data and DL / UL control information.

[0059] In NR, synchronization signal blocks (SS) are transmitted. In certain aspects, each SSB may be transmitted in a burst, where each SSB in the burst corresponds to a different beam direction for UE-side beam management (e.g., including beam selection and / or beam refinement). The SSB includes the PSS, SSS, and a two-symbol PBCH. The SSB may be transmitted at a fixed time slot position (such as Figure 3 ) is transmitted in the codewords 0-3 shown in . PSS and SSS can be used by UE for cell search and acquisition. PSS can provide half-frame timing, and SS can provide CP length and frame timing. PSS and SSS can provide cell identity. PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frames, SS burst set periodicity, system frame number, etc. SSB can be organized into SS bursts to support beam sweeping. Further system information (such as remaining minimum system information (RMSI), system information block (SIB), other system information (OSI)) can be transmitted on the physical downlink shared channel (PDSCH) in certain subframes. SSB can be transmitted up to 64 times, for example, up to 64 different beam directions for mmW. Multiple transmissions of SSB are called SS burst sets. SSBs in an SS burst set can be transmitted in the same frequency region, while SSBs in different SS burst sets can be transmitted in different frequency regions.

[0060] Random Access Channel (RACH) refers to a radio channel (medium) that can be shared by multiple UEs and can be used by these UEs to (randomly) access the network for communication. For example, RACH can be used for call setup and access to the network for data transmission. In some cases, RACH can be used for initial access to the network when the UE switches from RRC connected idle mode to active mode, or when switching in RRC connected mode. In addition, RACH can be used for downlink (DL) and / or uplink (UL) data arrival when the UE is in RRC idle or RRC inactive mode, and when reestablishing a connection with the network.

[0061] Figure 44 is a timing (or "call flow") diagram 400 illustrating an example four-step RACH procedure. At 402, a first message (MSG1) may be sent from UE 120a to BS110a on a physical random access channel (PRACH). In a four-step RACH procedure, MSG1 may include only a RACH preamble. At 404, BS110a may respond with a random access response (RAR) message (MSG2), which may include an identifier (ID) of the RACH preamble, a timing advance (TA), an uplink grant, a cell radio network temporary identifier (C-RNTI), and / or a backoff indicator. As illustrated, MSG2 may include a PDCCH communication that includes control information about subsequent communications on the PDSCH. At 406, in response to MSG2, UE 120a transmits MSG3 to BS110a on the PUSCH. MSG3 may include one or more of an RRC connection request, a tracking area update (TAU) request, a system information request, a location fix or positioning signal request, or a scheduling request. Subsequently, at 408, BS 110a responds with MSG 4, which may include a contention resolution message.

[0062] In some cases, to speed up access, a two-step RACH procedure may be supported. As the name implies, the two-step RACH procedure effectively "collapses" the four messages of the four-step RACH procedure into two messages. There are several benefits to the two-step RACH procedure, such as access speed and the ability to send relatively small amounts of data without the overhead of the entire four-step RACH procedure to establish a connection (when the four-step RACH message may be larger than the payload). The two-step RACH procedure can operate in any RRC state and with any supported cell size. Networks using the two-step RACH procedure can typically support contention-based random access (CBRA) message (e.g., MSG A) transmissions within a limited range of payload sizes and with a limited number of modulation and coding scheme (MCS) levels.

[0063] Figure 55 is a timing diagram 500 illustrating an example two-step RACH procedure according to certain aspects of the present disclosure. In the two-step RACH procedure, at 502, a first message (MSG A) may be sent from UE 120a to BS110a. MSG A may include some or all information from MSG1 and MSG3 of the four-step RACH procedure (effectively combining MSG1 and MSG3). For example, MSG A may include MSG1 and MSG3 multiplexed together, such as using one of time division multiplexing (TDM) or frequency division multiplexing (FDM). MSG A may include a RACH preamble and a payload for random access. For example, the MSG A payload may include a UE-ID and other signaling information (e.g., a buffer status report (BSR) or a scheduling request (SR)). At 504, BS110a may respond with a RAR message (MSG B) that may effectively combine MSG2 and MSG4 of the four-step RACH procedure described above. For example, MSG B may include an ID of a RACH preamble (RAPID), a timing advance (TA), a backoff indicator, a contention resolution message, a UL / DL grant, and / or a transmit power control (TPC) command.

[0064] Figure 6 6 is a timing diagram 600 illustrating a more detailed example of a two-step RACH procedure in accordance with certain aspects of the present disclosure. Figure 6 As shown, UE 120a may receive information from the BS prior to a RACH procedure and decode the information (such as SSB, system information block (SIB) and / or RS), which may be used by UE 120a to perform a RACH procedure with BS 110a. Figure 6 As shown, in a two-step RACH procedure, MSG A may include both a preamble (e.g., PRACH) and a payload (e.g., DMRS and PUSCH). The BS attempts to decode the process / decodes the MSG A preamble and payload, and then sends MSG B (e.g., based on the processing of MSG A). Figure 6 As shown, MSG B may include both PDCCH and PDSCH.

[0065] Fig. 7A 1 illustrates a channel structure for an example MSG A transmission opportunity that may be verified in accordance with certain aspects of the present disclosure. Fig. 7A As shown in FIG. 1 , the MSG A transmission opportunity generally includes a MSG A preamble opportunity (for transmitting a preamble signal) and a MSG A payload opportunity for transmitting a PUSCH. Fig. 7AAs illustrated, MSGA preamble transmission may involve (1) selection of a preamble sequence; and (2) selection of a preamble opportunity in the time / frequency domain (for transmitting the selected preamble sequence). MSGA payload transmission may involve: (1) construction of a random access message payload (DMRS / PUSCH); and (2) selection of one or more PUSCH resource units (PRUs) in the time / frequency domain to transmit the message (payload). Figure 7B As illustrated, the UE monitors SSB transmissions that are transmitted (e.g., repeatedly transmitted by the BS using different TX beams) and are associated with a limited set of time / frequency resources that define RACH opportunities (RO) and PRUs. A RACH preamble opportunity (RO) may be a time and frequency resource assigned to a preamble transmission.

[0066] Once an SSB is detected, the UE may select a RO and one or more PRUs associated with the SSB for transmission by MSG A. A limited set of ROs and PRUs may help reduce the monitoring overhead (blind decoding) of the base station.

[0067] In some systems (e.g., 5G NR), up to 64 preamble sequences are configured on each RO. Multiple four-step and / or multiple two-step RACH UEs can share the same RO and randomly select their preamble sequences from a common pool. In some examples, the network configures separate ROs for two-step and four-step RACH UEs, or the network configures separate pools for two-step and four-step RACH UEs but configures a shared RO.

[0068] As mentioned above, MSG B can be unicast or multicast. In some cases, unicast MSG B may be desirable / supportable, while in other cases, multicast MSG B may be desirable / supportable. Unicast MSG B may allow the BS to send a large payload to the UE, while multicast MSG B may reduce the complexity of blind decoding and allow the RACH response message to carry multiple small payloads for multiple UEs.

[0069] Example Configurable Patterns for Responses to Random Access Messages

[0070] Various aspects of the present disclosure provide configurable modes for random access channel (RACH) response message (e.g., MSG B) transmission and construction. In some examples, the network may configure the mode (e.g., unicast or multicast) based on various parameters such as system load (e.g., how many user equipment (UE) will perform two-step RACH procedures simultaneously), cell coverage, and resource availability (e.g., how many time / frequency resources and RACH sequences are available). For example, in the case where the system load is high and / or the physical downlink control channel (PDCCH) payload is large, the unicast mode may be used, while in the case where the system load is low and / or the PDCCH payload is small, the multicast mode may be used.

[0071] The configured mode may be indicated to the UE. Indicating the mode may allow determination of a search space for monitoring / decoding the RACH response message. In addition, the UE may be aware of the multi-access signature based on the indicated mode. In some examples, the content of the RACH response message may depend on the radio resource control (RRC) state of the UE and / or based on the processing of the RACH message (e.g., MSG A).

[0072] According to certain aspects, in unicast mode of a RACH response message, the PDCCH of the RACH response message carries a downlink assignment of a physical downlink shared channel (PDSCH) for the RACH response message for a single two-step UE. The PDCCH of the RACH response message is transmitted in a UE-specific search space (USS). In some examples, a cyclic redundancy check (CRC) of the PDCCH of the unicast RACH response message is masked by a UE-specific multi-access signature (e.g., represented by msgB-RNTI_1). Therefore, based on indicating the unicast mode, the UE knows to monitor / decode the PDCCH of the RACH response message in the USS (whose CRC is masked by the multi-access signature).

[0073] According to certain aspects, the multi-access signature depends on the result of the RACH message (e.g., MSG A) processing and the RRC state of the UE. For example, in the case where the UE is in the RRC idle or RRC inactive state and the BS detects the RACH message, the multi-access signature (e.g., msgB_RNTI_1) can be calculated, such as by a weighted combination of the resource index (including the RO index, the preamble index, and the UL carrier index) used for the RACH message transmission. In one example, the multi-access signature can be calculated as follows:

[0074] msgB_RNTI_1=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8x 2x rf_id+C_1+C_2*PRACH_preamble_id,

[0075] Where rf_id is the modulo operation of the radio frame index (rf_id = (radio frame index) mod 2 + 1), PRACH_preamble_id is the index of the preamble sequence on the selected RO (0 ≤ PRACH_preamble_id < 64), s_id is the index of the first OFDM symbol of the specified PRACH (0 ≤ s_id < 14), t_id is the index of the first time slot symbol of the specified PRACH in the system frame (0 ≤ t_id < 80), f_id is the index of the specified PRACH in the frequency domain (0 ≤ f_id < 8), ul_carrier_id is the UL carrier used for RACH message (e.g., MSG A) transmission (0 = normal carrier, 1 = SUL carrier), C_1 ≥ 1 and C_2 ≥ 0 are constants. Otherwise, in the case that the BS does not detect the RACH message, the BS does not need to transmit the RACH response message.

[0076] In another example, in the case where the UE is in RRC connected state and the BS detects the RACH message payload, the UE's multi-access signature (C-RNTI) may be used (e.g., used as msgB_RNTI_1). Otherwise, in the case where the BS only detects the RACH preamble, the same formula described above for RRC_IDLE or RRC_INACTIVE UEs may be reused.

[0077] To mitigate potential conflicts between C-RNTI and other multi-access signatures (e.g., msgB_RNTI_1) values, a 1-bit flag for C-RNTI may be carried in the downlink control information (DCI) of the PDCCH of the RACH response message. The 1-bit flag may indicate whether the multi-access signature is C-RNTI or msgB_RNTI_1.

[0078] According to certain aspects, in unicast mode for RACH response message, the PDSCH of RACH response message carries response information for a single UE. According to certain aspects, the content of unicast RACH response message depends on the result of RACH message (eg, MSGA) processing and the RRC state of the UE. Figure 8 8 is a table 800 showing example contents of a unicast RACH response message PDCCH and PDSCH depending on the RRC state and whether the BS successfully decodes the RACH payload and preamble from the UE.

[0079] According to certain aspects, in a multicast mode for a RACH response message, a PDCCH for the RACH response message is transmitted in a common search space (CSS). The PDCCH for the RACH response message carries a DL assignment of a MSG B PDSCH for a group of two-step RACH UEs. In some examples, a CRC of the PDCCH for the RACH response message is masked by a group-specific multi-access signature (e.g., represented by msgB-RNTI). In the case where two-step RACH and four-step RACH share the same RO, the PDCCH for the RACH response message may be distinguished from the msg2 PDCCH. For example, the PDCCH for RACH response messages for two-step and four-step RACH may be distinguished based on different control resource sets (CORESETs), different search space configurations for msgB PDCCH and msg2 PDCCH, different quasi co-location (QCL) relationships, different demodulation reference signal (DMRS) resource configurations, and / or different values ​​of the multi-access signature (e.g., different msgB-RNTI_2 and random access radio network temporary identifier (RA-RNTI)).

[0080] According to certain aspects, for a multicast RACH response message, the PDSCH of the RACH response message carries an aggregation of response information for each UE in the group. According to certain aspects, the content of the multicast RACH response message depends on the result of the RACH message (eg, MSGA) processing and the RRC state of the UE. Fig. 9 9 is a table 900 showing example contents of a multicast RACH response message PDCCH and PDSCH depending on the RRC state and whether the BS successfully decodes the RACH payload and preamble from the UE.

[0081] Fig.10 and 11 1000 and 1100, respectively, for wireless communication in accordance with certain aspects of the present disclosure. Operations 1000 and 1100 may be performed, for example, by a BS (such as, for example, BS 110a in wireless communication network 100). Operations 1000 and 1100 may be implemented as a processor on one or more processors (e.g., Figure 2 In addition, signal transmission and reception by the BS in operations 1000 and 1100 may be performed by one or more antennas (e.g., Figure 2 In some aspects, signal transmission and / or reception by the BS may be achieved by obtaining and / or outputting signals via a bus interface of one or more processors (eg, controller / processor 240).

[0082] Operations 1000 may begin by receiving a RACH message from a UE at 1002. The RACH message includes a RACH preamble transmission and a PUSCH transmission.

[0083] At 1004, the BS sends a RACH response message to the UE. The RACH response message includes a PDCCH transmission and a PDSCH transmission. At 1006, sending the RACH message to the UE includes scrambling a CRC associated with the PDCCH transmission of the RACH response message, the CRC being masked by a UE-specific or group-specific multi-access signature; and at 1008, sending a PDSCH to the UE based on the PDCCH.

[0084] Operations 1100 may begin at 1102 by determining to operate according to a first mode in which the BS unicasts downlink RACH response message (e.g., MSG B) transmissions during a two-step RACH procedure or a second mode in which the BS multicasts downlink RACH response message transmissions during a two-step RACH procedure. The downlink RACH response message includes a PDCCH transmission and a PDSCH transmission.

[0085] At 1204, the BS provides an indication of the determined first mode or second mode to at least one UE.

[0086] In a first aspect, the determination is based on at least one of: system loading, cell coverage, or resource availability.

[0087] In a second aspect, alone or in combination with the first aspect, the indication is broadcast in system information or transmitted to the at least one UE via RRC signaling before performing the two-step RACH procedure.

[0088] In a third aspect, alone or in combination with one or more of the first and second aspects, the BS further performs a two-step RACH procedure with at least one UE according to the indicated first mode or second mode.

[0089] In a fourth aspect, alone or in combination with one or more of the first to third aspects, performing a RACH procedure with at least one UE includes: determining whether the BS successfully decodes a RACH preamble and a RACH payload in an uplink RACH message from the UE; and determining an RRC state of the UE.

[0090] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, determining whether the BS receives a RACH preamble from the UE includes: determining whether the BS successfully decodes the RACH preamble during an assigned RACH preamble opportunity (RO); determining whether the BS receives a RACH payload includes determining whether the BS successfully decodes the RACH payload during an assigned RACH payload opportunity; and determining the RRC state of the UE is at least partially based on an indication from the UE in an uplink RACH message.

[0091] In a sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the content of the downlink RACH response message is based on the determined first mode or second mode, the RRC state of the UE, and whether the BS successfully decodes the RACH preamble and RACH payload from the UE.

[0092] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, performing a RACH procedure with at least one UE includes: DTX (discontinuous transmission) or sending a downlink RACH response message with BI when the BS fails to successfully decode the RACH preamble.

[0093] In an eighth aspect, alone or in combination with one or more of the first to seventh aspects, when the BS successfully decodes the RACH preamble but fails to successfully decode the RACH payload, the PDSCH transmission of the RACH response message transmission carries at least the TAC and the fallback RAR.

[0094] In a ninth aspect, either alone or in combination with one or more of the first to eighth aspects, when the BS successfully decodes the RACH preamble but fails to successfully decode the RACH payload, the PDCCH transmission of the RACH response message transmission carries at least a downlink assignment for the PDSCH transmission of the RACH response message transmission.

[0095] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, the PDCCH transmission of the RACH response message transmission further carries a PUCCH resource configuration of a HARQ procedure of the PDSCH transmission of the RACH response message transmission.

[0096] In an eleventh aspect, alone or in combination with one or more of the first to tenth aspects, when the BS successfully decodes the RACH payload and the UE is in an RRC connected state, the PDSCH transmission of the RACH response message transmission carries at least the TAC.

[0097] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, the PDSCH transmission of the RACH response message transmission further carries at least one of: an RRC message or an uplink grant for new data.

[0098] In a thirteenth aspect, alone or in combination with one or more of the first to twelfth aspects, when the BS successfully decodes the RACH payload and the UE is in RRC inactive or RRC idle state, the PDSCH transmission of the RACH response message transmission carries at least a successful RAR and TAC.

[0099] In the fourteenth aspect, either alone or in combination with one or more of the first to thirteenth aspects, the PDSCH transmission of the RACH response message transmission further carries at least one of: an RRC message, an uplink grant for new data, or a PUCCH resource configuration of the HARQ procedure for the PDSCH transmission of the RACH response message transmission.

[0100] In a fifteenth aspect, alone or in combination with one or more of the first to fourteenth aspects, performing a RACH procedure with at least one UE includes: when the BS operates according to a first mode, unicasting a PDCCH transmission of a RACH response message transmission in a USS configured for the PDCCH, the PDCCH transmission carrying a downlink assignment for a PDSCH transmission of the RACH response message transmission, wherein the PDSCH transmission carries response information for a single UE.

[0101] In a sixteenth aspect, alone or in combination with one or more of the first to fifteenth aspects, a CRC associated with a PDCCH transmission of a RACH response message transmission is masked by a UE-specific multi-access signature; when the BS successfully decodes the RACH payload and the UE is in an RRC inactive or RRC idle state, the signature is calculated based on resources used for at least one of the following: a RACH preamble or a RACH payload; and when the BS successfully decodes the RACH payload, the multi-access signature is a unique identifier (e.g., C-RNTI) assigned to the UE in an RRC connected state; and when the BS decodes the RACH preamble but fails to successfully decode the RACH payload, the multi-access signature for the RRC connected UE may use the same formula as that for the RRC inactive or RRC idle UE.

[0102] In the seventeenth aspect, either alone or in combination with one or more of the first to sixteenth aspects, a flag in the DCI transmitted by the PDCCH of the RACH response message transmission indicates whether the signature is calculated for a UE in an RRC inactive or idle state, or is a unique identifier assigned to a UE in an RRC connected state.

[0103] In an eighteenth aspect, alone or in combination with one or more of the first to seventeenth aspects, the PDCCH transmission of the RACH response message transmission further indicates the configuration of PUCCH resources for HARQ feedback of the PDSCH transmission of the RACH response message transmission.

[0104] In a nineteenth aspect, alone or in combination with one or more of the first to eighteenth aspects, performing a RACH procedure with at least one UE includes: when the BS operates according to a second mode, transmitting a PDCCH transmission for a RACH response message transmission in a CSS configured for a group common PDCCH, the PDCCH transmission carrying a downlink assignment for a PDSCH transmission for the RACH response message transmission.

[0105] In a twentieth aspect, either alone or in combination with one or more of the first to nineteenth aspects, a CRC associated with the PDCCH is masked by a group-specific multi-access signature that is different from a signature associated with the PDCCH for the first mode.

[0106] In the twenty-first aspect, alone or in combination with one or more of the first to twentieth aspects, the PDCCH transmission for the RACH response message transmission for the two-step RACH procedure uses at least one of the following: a different CORESET, a different search space configuration, a different QCL relationship, a different DMRS resource configuration, or a different multi-access signature than the PDCCH transmission for the RACH response message (message 2) transmitted by the BS for the four-step RACH procedure.

[0107] In the twenty-second aspect, alone or in combination with one or more of the first to twenty-first aspects, when the BS successfully decodes the RACH payload and the UE is in an RRC connected state, the PDCCH transmission of the RACH response message transmission further carries an indication of PUCCH resources for HARQ feedback of the PDSCH transmission of the RACH response message transmission.

[0108] In the twenty-third aspect, either alone or in combination with one or more of the first to twenty-second aspects, when the BS successfully decodes the RACH payload and the UE is in an RRC inactive or RRC idle state, the PDSCH transmission of the RACH response message transmission further carries an indication of a physical uplink control channel (PUCCH) resource for HARQ feedback.

[0109] Fig.12 and 131 is a flowchart illustrating example operations 1200 and 1300 for wireless communication, respectively, according to certain aspects of the present disclosure. Operations 1200 and 1300 may be performed, for example, by a UE (such as, for example, UE 120a in wireless communication network 100). Operations 1200 and 1300 may be operations performed by the UE that are complementary to operations 1000 and 1100, respectively, performed by a BS. Operations 1200 and 1300 may be implemented as a processor (e.g., Figure 2 In addition, signal transmission and reception by the UE in operations 1200 and 1300 may be performed by one or more antennas (e.g., Figure 2 In some aspects, the transmission and / or reception of signals by the UE may be achieved by obtaining and / or outputting signals via a bus interface of one or more processors (eg, controller / processor 280).

[0110] Operations 1200 may begin by sending a RACH message to a BS at 1202. The RACH message includes a RACH preamble transmission and a PUSCH transmission.

[0111] The UE receives a RACH response message from the BS at 1204. The RACH message from the BS includes a PDCCH transmission and a PDSCH transmission.

[0112] At 1206, receiving the RACH response message from the BS includes descrambling a CRC associated with a PDCCH transmission of the RACH response message, the CRC masked by a UE-specific or group-specific multi-access signature; and at 1208, monitoring a PDSCH based on the PDCCH.

[0113] At 1302, operation 1300 may begin by receiving an indication from a BS that the BS is operating according to a first mode or a second mode, wherein the first mode BS unicasts a downlink RACH response message during a two-step RACH procedure, and the second mode BS multicasts a downlink RACH response message during a two-step RACH procedure, the downlink RACH response message transmission including a PDCCH transmission and a PDSCH transmission.

[0114] At 1304, the UE sends an uplink RACH message transmission including a RACH preamble and a RACH payload to the BS.

[0115] At 1306, the UE monitors and decodes the PDCCH transmission of the downlink RACH response message from the BS based on the indicated first mode or second mode.

[0116] At 1308, the UE decodes the PDSCH transmission of the downlink RACH response message transmission based on the indicated first mode or second mode and sends HARQ feedback to the BS.

[0117] In a first aspect, the indication is broadcast from the BS in system information or transmitted via RRC signaling before performing the two-step RACH procedure.

[0118] In a second aspect, alone or in combination with the first aspect, a RACH preamble is transmitted during an assigned RO; and a RACH payload is transmitted during an assigned RACH payload opportunity.

[0119] In a third aspect, alone or in combination with one or more of the first and second aspects, the UE further provides an indication of the RRC state of the UE in an uplink RACH message transmission.

[0120] In a fourth aspect, alone or in combination with one or more of the first to third aspects, a PDSCH transmission of a RACH response message transmission carries at least a TAC and a fallback RAR.

[0121] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, a PDCCH transmission of a RACH response message transmission carries at least a downlink assignment for a PDSCH transmission of the RACH response message transmission.

[0122] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, the PDCCH transmission of the RACH response message transmission further carries a PUCCH resource configuration of a HARQ procedure of the PDSCH transmission of the RACH response message transmission.

[0123] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, when the UE is in an RRC connected state, a PDSCH transmission of a RACH response message transmission carries at least a TAC.

[0124] In an eighth aspect, alone or in combination with one or more of the first to seventh aspects, the PDSCH transmission of the RACH response message transmission further carries at least one of: an RRC message or an uplink grant for new data.

[0125] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, when the UE is in an RRC inactive or RRC idle state, the PDSCH transmission of the RACH response message transmission carries at least a successful RAR and TAC.

[0126] In the tenth aspect, either alone or in combination with one or more of the first to ninth aspects, the PDSCH transmission of the RACH response message transmission further carries at least one of the following: an RRC message, an uplink grant for new data, or a PUCCH resource configuration of the HARQ procedure for the PDSCH transmission of the RACH response message transmission.

[0127] In the eleventh aspect, alone or in combination with one or more of the first to tenth aspects, monitoring PDCCH transmission for a downlink RACH response message transmission includes, when the BS operates according to the first mode, monitoring a unicast PDCCH transmission for a RACH response message transmission in a USS configured for the PDCCH, the unicast PDCCH transmission carrying a downlink assignment for a PDSCH transmission for the RACH response message transmission, wherein the PDSCH transmission carries response information for a single UE.

[0128] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, the UE descrambles a CRC associated with a PDCCH transmission of a RACH response message transmission that is masked by a UE-specific multi-access signature, wherein the signature is calculated based on resources used for at least one of: a RACH preamble or a RACH payload; or the multi-access signature is a unique identifier (e.g., C-RNTI) assigned to a UE in an RRC connected state.

[0129] In the thirteenth aspect, alone or in combination with one or more of the first to twelfth aspects, a flag in the downlink control information of the PDCCH transmission of the RACH response message indicates whether the signature is calculated for a UE in an RRC inactive or idle state, or is a unique identifier assigned to a UE in an RRC connected state.

[0130] In a fourteenth aspect, alone or in combination with one or more of the first to thirteenth aspects, the PDCCH transmission of the RACH response message transmission further indicates a configuration of PUCCH resources for HARQ feedback of the PDSCH transmission of the RACH response message transmission.

[0131] In a fifteenth aspect, alone or in combination with one or more of the first to fourteenth aspects, monitoring a PDCCH transmission for a downlink RACH response message transmission includes, when the BS operates according to a second mode, transmitting a PDCCH transmission for a RACH response message transmission in a CSS configured for a group common PDCCH, the PDCCH transmission carrying a downlink assignment for a PDSCH transmission for the RACH response message transmission.

[0132] In a sixteenth aspect, either alone or in combination with one or more of the first to fifteenth aspects, the UE descrambles a CRC associated with a PDCCH masked by a group-specific multi-access signature that is different from a signature associated with the PDCCH used for the first mode.

[0133] In the seventeenth aspect, alone or in combination with one or more of the first to sixteenth aspects, the UE monitors the PDCCH transmission of the RACH response message for the two-step RACH procedure based on at least one of the following: a different CORESET, a different search space configuration, a different QCL relationship, a different DMRS resource configuration, or a different multi-access signature than the PDCCH transmission of the RACH response message (message 2) transmitted by the BS for the four-step RACH procedure.

[0134] In the eighteenth aspect, alone or in combination with one or more of the first to seventeenth aspects, when the UE is in an RRC connected state, the PDCCH transmission of the RACH response message transmission further carries an indication of PUCCH resources for HARQ feedback of the PDSCH transmission of the RACH response message transmission.

[0135] In a nineteenth aspect, alone or in combination with one or more of the first to eighteenth aspects, when the UE is in an RRC inactive or RRC idle state, the PDSCH transmission of the RACH response message transmission further carries an indication of PUCCH resources for HARQ feedback.

[0136] Fig.14 The following describes operations that may include being configured to perform the techniques disclosed herein (such as Fig.10 and / or Fig.10 1400 includes a communication device 1400 having various components (e.g., corresponding to means plus function components) of the operations explained in the foregoing. The communication device 1400 includes a processing system 1402 coupled to a transceiver 1408. The transceiver 1408 is configured to transmit and receive signals (such as various signals as described herein) for the communication device 1400 via an antenna 1410. The processing system 1402 can be configured to perform processing functions for the communication device 1400, including processing signals received and / or to be transmitted by the communication device 1400.

[0137] The processing system 1402 includes a processor 1404 coupled to a computer-readable medium / memory 1412 via a bus 1406. In some aspects, the computer-readable medium / memory 1412 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1404, cause the processor 1404 to perform Fig.10 and / or Fig.11, or other operations for performing the various techniques discussed herein for configurable modes of responses to random access messages. In certain aspects, according to aspects of the present disclosure, the computer-readable medium / memory 1412 stores code 1414 for receiving; code 1416 for sending; code 1418 for scrambling; code 1420 for determining; and / or code 1422 for providing. In certain aspects, the processor 1404 has a circuit system configured to implement the code stored in the computer-readable medium / memory 1412. According to aspects of the present disclosure, the processor 1404 includes circuit systems 1424 for receiving; circuit systems 1426 for sending; circuit systems 1428 for scrambling; circuit systems 1430 for determining; and / or circuit systems 1432 for providing.

[0138] Fig.15 The following describes operations that may include being configured to perform the techniques disclosed herein (such as Fig.12 and / or Fig.13 1500 includes a communication device 1500 including various components (e.g., corresponding to means plus function components) of the operations explained in the foregoing. The communication device 1500 includes a processing system 1502 coupled to a transceiver 1508. The transceiver 1508 is configured to transmit and receive signals (such as various signals as described herein) for the communication device 1500 via an antenna 1510. The processing system 1502 may be configured to perform processing functions for the communication device 1500, including processing signals received and / or to be transmitted by the communication device 1500.

[0139] The processing system 1502 includes a processor 1504 coupled to a computer-readable medium / memory 1512 via a bus 1506. In some aspects, the computer-readable medium / memory 1512 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1504, cause the processor 1504 to perform Fig.12 and / or Fig.13, or other operations for performing the various techniques discussed herein for configurable modes of responses to random access messages. In certain aspects, according to aspects of the present disclosure, the computer-readable medium / memory 1512 stores code 1514 for receiving; code 1516 for transmitting; code 1518 for descrambling; code 1520 for monitoring; and / or code 1522 for decoding. In certain aspects, the processor 1504 has a circuit system configured to implement the code stored in the computer-readable medium / memory 1512. According to aspects of the present disclosure, the processor 1504 includes circuit systems 1524 for receiving; circuit systems 1526 for transmitting; circuit systems 1528 for descrambling; circuit systems 1530 for monitoring; and / or circuit systems 1532 for decoding.

[0140] The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), Advanced LTE (LTE-A), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network may implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks can implement radio technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). NR is an emerging wireless communication technology under development.

[0141] The techniques described herein can be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, although various aspects may be described herein using terms commonly associated with 3G, 4G and / or 5G wireless technologies, various aspects of the present disclosure may be applied in communication systems based on other generations.

[0142] In 3GPP, the term "cell" may refer to the coverage area of ​​a B node (NB) and / or a NB subsystem serving the coverage area, depending on the context in which the term is used. In NR systems, the terms "cell" and BS, next-generation B node (gNB or g B node), access point (AP), distributed unit (DU), carrier, or transmission reception point (TRP) may be used interchangeably. The BS may provide communication coverage for macro cells, pico cells, femto cells, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., a radius of several thousand meters) and may allow unrestricted access by UEs with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in a residence, etc.). 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.

[0143] UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smart phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet computer, camera, gaming device, netbook, smartbook, ultrabook, appliance, medical device or medical equipment, biometric sensor / device, wearable device (such as smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), entertainment device (e.g., music device, video device, satellite radio, etc.), transportation component or sensor, smart meter / sensor, industrial manufacturing equipment, global positioning system device, or any other suitable device configured to communicate via wireless or wired medium. Some UEs may be considered machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which can communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node can provide connectivity for or to a network (e.g., a wide area network (such as the Internet) or a cellular network), for example, via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

[0144] In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., BS) allocates resources for communication between some or all devices and equipment within its service area or cell. A scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, subordinate entities utilize resources allocated by the scheduling entity. A base station is not the only entity that can be used as a scheduling entity. In some examples, a UE may act as a scheduling entity, and may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and other UEs may utilize resources scheduled by the UE for wireless communication. In some examples, a UE may act as a scheduling entity in a peer-to-peer (P2P) network and / or in a mesh network. In a mesh network example, UEs may communicate directly with each other in addition to communicating with a scheduling entity.

[0145] In some examples, two or more subordinate entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh networks, and / or various other suitable applications. Generally, a sidelink signal may refer to a signal that is communicated from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., UE or BS), even if the scheduling entity may be used for scheduling and / or control purposes. In some examples, the sidelink signal may be communicated using a licensed spectrum (unlike wireless local area networks, which typically use an unlicensed spectrum).

[0146] Each method disclosed herein includes one or more steps or actions for implementing the method. These method steps and / or actions can be interchangeable with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be changed without departing from the scope of the claims.

[0147] As used herein, 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, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0148] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, a database, or another data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining" may include resolving, selecting, choosing, establishing, and the like.

[0149] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be easily understood by those skilled in the art, and the universal principles defined herein can be applied to other aspects. Thus, the claims are not intended to be limited to the various aspects shown herein, but should be granted the full scope consistent with the language of the claims, wherein the singular reference to the element is not intended to mean "there is and only one" (unless specifically stated) but "one or more". Unless otherwise specifically stated, the term "some / some" refers to one or more. The elements of the various aspects described throughout this disclosure are all structural and functional equivalents currently or hereafter known to those of ordinary skill in the art and are expressly incorporated herein by reference, and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be donated to the public, regardless of whether such disclosure is explicitly recorded in the claims. Any element of the claim should not be interpreted under the provisions of 35 U.S.C. § 112 (f), unless the element is explicitly stated using the phrase "device for..." or in the case of a method claim, the element is stated using the phrase "step for...".

[0150] The various operations of the methods described above may be performed by any suitable device capable of performing the corresponding functions. These devices may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs), or processors. Generally, where there are operations illustrated in the accompanying drawings, these operations may have corresponding paired device-plus-function components with similar numbers.

[0151] The various illustrative logical blocks, modules, and circuits described in conjunction with the present disclosure may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0152] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus may link together various circuits including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter, etc., to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In a user terminal (see Figure 1 ), a user interface (e.g., a keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art and will not be described further. The processor may be implemented with one or more general and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuit systems capable of executing software. Those skilled in the art will recognize how to best implement the functionality described with respect to the processing system, depending on the specific application and the overall design constraints imposed on the overall system.

[0153] If implemented in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Software should be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or other. Computer-readable media include both computer storage media and communication media, which include any media that facilitate the transfer of computer programs from one place to another. The processor may be responsible for managing the bus and general processing, including executing software modules stored on a machine-readable storage medium. A computer-readable storage medium may be coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. As an example, a machine-readable medium may include a transmission line, a carrier modulated by data, and / or a computer-readable storage medium having instructions stored thereon that is separated from a wireless node, all of which may be accessed by a processor through a bus interface. Alternatively or additionally, a machine-readable medium or any part thereof may be integrated into a processor, such as a cache and / or a general register file, which may be the case. As an example, examples of machine-readable storage media may include RAM (random access memory), flash memory, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable programmable read only memory), EEPROM (electrically erasable programmable read only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage media, or any combination thereof. Machine-readable media may be implemented in a computer program product.

[0154] A software module may include a single instruction, or many instructions, and may be distributed over several different code segments, distributed between different programs, and distributed across multiple storage media. A computer-readable medium may include several software modules. These software modules include instructions that cause a processing system to perform various functions when executed by an apparatus such as a processor. These software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or may be distributed across multiple storage devices. As an example, when a triggering event occurs, a software module may be loaded into a RAM from a hard drive. During the execution of a software module, a processor may load some instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When describing the functionality of a software module as described below, it will be understood that such functionality is implemented by the processor when the processor executes instructions from the software module.

[0155] Likewise, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared (IR), radio, and microwave), then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Disks, where disks often reproduce data magnetically, and discs reproduce data optically with lasers. Thus, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). Additionally, for other aspects, computer-readable media may include transient computer-readable media (e.g., signals). Combinations of the above should also be included within the scope of computer-readable media.

[0156] Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having stored (and / or encoded) thereon instructions that can be executed by one or more processors to perform the operations described herein, such as for performing the operations described herein and in Figure 10-13 Instructions for the operations explained in .

[0157] In addition, it should be appreciated that modules and / or other appropriate means for performing the methods and techniques described herein may be downloaded and / or otherwise obtained by a user terminal and / or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk, etc.) so that once the storage device is coupled to or provided to a user terminal and / or base station, the device can obtain the various methods. In addition, any other suitable technology suitable for providing the methods and techniques described herein to a device may be utilized.

[0158] It will be understood that the claims are not limited to the precise configuration and components illustrated above. Various changes, substitutions and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method for wireless communication by a user equipment UE, the method comprising: Sending a random access channel RACH message to a base station BS for a two-step random access RA procedure, wherein the RACH message includes a RACH preamble transmission and a physical uplink shared channel PUSCH transmission; and Receiving a RACH response message from the BS, the RACH response message from the BS comprising a physical downlink control channel PDCCH transmission and a physical downlink shared channel PDSCH transmission, wherein receiving the RACH response message from the BS comprises: When the RACH message is for a contention-free random access CFRA two-step RA procedure: monitoring the PDCCH transmission of the RACH response message in a UE-specific search space USS; descrambling a cyclic redundancy check CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a UE-specific cell radio network temporary identifier C-RNTI or a UE-specific message B msgB RNTI; and monitoring the PDSCH transmission of the RACH response message based on the PDCCH transmission of the RACH response message; and When the RACH message is for contention-based random access (CBRA) two-step RA procedure: monitoring the PDCCH transmission of the RACH response message in a common search space CSS; descrambling the CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a group-specific RNTI; and The PDSCH transmission of the RACH response message is monitored based on the PDCCH transmission of the RACH response message, wherein the PDSCH transmission includes a UE-specific RNTI or a msgB RNTI.

2. The method of claim 1, wherein the RACH response message comprises at least one of the following: a backoff indicator BI, a timing advance command TAC, a fallback random access response RAR, a successful RAR, or a combination thereof.

3. The method of claim 1, further comprising receiving an indication from the BS to monitor the USS for the PDCCH transmission having the CRC scrambled with the UE-specific C-RNTI or msgB RNTI, or to monitor the CSS for the PDCCH transmission having the CRC scrambled with the group-specific RNTI.

4. The method of claim 3, wherein the indication from the BS comprises an indication to monitor the PDCCH transmission with the CRC scrambled with the UE-specific C-RNTI or msgB RNTI at high system load.

5. The method of claim 4, further comprising receiving an indication from the BS to monitor a RACH response message including a PDCCH transmission having a CRC scrambled with a group-specific RNTI when system load is low.

6. The method of claim 3, wherein the indication from the BS comprises an indication to monitor the PDCCH transmission with the CRC scrambled with the UE-specific C-RNTI or msgB RNTI when the PDCCH transmission has a large payload.

7. The method of claim 6, further comprising receiving an indication from the BS to monitor a RACH response message including a PDCCH transmission having a CRC scrambled with a group-specific RNTI when the PDCCH transmission has a small payload.

8. The method of claim 1, wherein when the UE is in a radio resource control (RRC) idle state or an RRC inactive state, the msgB RNTI is calculated based on one or more RACH opportunity indexes and an uplink carrier index.

9. The method of claim 8, wherein the C-RNTI is used when the UE is in an RRC connected state.

10. The method of claim 1, wherein the PDCCH transmission of the RACH response message further comprises a flag indicating that the group-specific RNTI is used for the RACH response message of a two-step RACH procedure.

11. The method of claim 1 , further comprising determining the msgB RNTI based on 1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8×2, wherein s_id is an index of a first orthogonal frequency division multiplexing (OFDM) symbol of a physical RACH PRACH opportunity, t_id is an index of a first time slot of the PRACH opportunity, f_id is an index of the PRACH opportunity in the frequency domain, and ul_carrier_id is an identifier of an uplink carrier.

12. The method of claim 3, wherein receiving the indication from the BS comprises: The indication is received from the BS in system information broadcast or radio resource control (RRC) signaling before sending the RACH message to the BS.

13. The method of claim 1, wherein the PDCCH transmission of the RACH response message further carries a physical uplink control channel (PUCCH) resource configuration for providing hybrid automatic repeat request (HARQ) feedback for the PDSCH transmission of the RACH response message.

14. The method according to claim 1, wherein when the UE is in a radio resource control (RRC) connected state, an RRC inactive state or an RRC idle state, the PDSCH transmission of the RACH response message carries at least a timing advance command (TAC).

15. The method of claim 14, wherein the PDSCH transmission of the RACH response message further carries at least one of: an RRC message or an uplink grant for new data.

16. The method of claim 14, wherein the PDSCH transmission of the RACH response message further carries at least one of: an RRC message, an uplink grant for new data, or a physical uplink control channel (PUCCH) resource configuration for providing hybrid automatic repeat request (HARQ) feedback for the PDSCH transmission of the RACH response message.

17. The method of claim 1, wherein the method further comprises: The PDCCH transmission of the RACH response message for the two-step RA procedure is monitored based on at least one of: a different control resource set CORESET, a different search space configuration, a different quasi-co-located QCL relationship, a different demodulation reference signal DMRS resource configuration, or a different multiple access signature than the PDCCH transmission of the RACH response message for the four-step RA procedure.

18. A method for wireless communication by a base station BS, the method comprising: receiving a random access channel (RACH) message from a user equipment (UE) for a two-step random access (RA) procedure, the RACH message including a RACH preamble transmission and a physical uplink shared channel (PUSCH) transmission; and Sending a RACH response message to the UE in a common search space CSS, where the RACH response message includes a physical downlink control channel PDCCH transmission and a physical downlink shared channel PDSCH transmission, wherein sending the RACH message to the UE includes: When the RACH message is for a contention-free random access CFRA two-step RA procedure: scrambling a cyclic redundancy check CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a UE-specific cell radio network temporary identifier C-RNTI or a UE-specific message B msgB RNTI; sending the PDCCH transmission of the RACH response message to the UE in a UE-specific search space USS; and sending the PDSCH transmission of the RACH response message to the UE based on the PDCCH transmission of the RACH response message; and When the RACH message is for contention-based random access (CBRA) two-step RA procedure: scrambling the CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a group-specific RNTI; sending the PDCCH transmission of the RACH response message in a common search space CSS; and The PDSCH transmission of the RACH response message is sent to the UE based on the PDCCH transmission of the RACH response message, wherein the PDSCH transmission of the RACH response message includes a UE-specific RNTI or a msgB RNTI.

19. The method of claim 18, wherein the RACH response message comprises at least one of: a backoff indicator (BI), a timing advance command (TAC), a fallback random access response (RAR), a successful RAR, or a combination thereof.

20. The method of claim 18, further comprising sending an indication to the UE to monitor the USS for the PDCCH transmission having the CRC scrambled with the UE-specific C-RNTI or msgB RNTI, or to monitor the CSS for the PDCCH transmission having the CRC scrambled with the group-specific RNTI.

21. The method of claim 20, wherein sending the indication to the UE comprises: The indication is sent to the UE in system information broadcast or radio resource control (RRC) signaling before receiving the RACH message from the UE.

22. The method of claim 18, wherein the PDCCH transmission of the RACH response message further carries a physical uplink control channel (PUCCH) resource configuration for providing hybrid automatic repeat request (HARQ) feedback for the PDSCH transmission of the RACH response message.

23. The method of claim 18, wherein when the UE is in a radio resource control (RRC) connected state, an RRC inactive state, or an RRC idle state, the PDSCH transmission of the RACH response message carries at least a timing advance command (TAC).

24. The method of claim 23, wherein the PDSCH transmission of the RACH response message further carries at least one of: an RRC message or an uplink grant for new data.

25. The method of claim 23, wherein the PDSCH transmission of the RACH response message further carries at least one of: an RRC message, an uplink grant for new data, or a physical uplink control channel (PUCCH) resource configuration for providing hybrid automatic repeat request (HARQ) feedback for the PDSCH transmission of the RACH response message.

26. The method of claim 18, wherein the PDCCH transmission of the RACH response message is for a two-step RACH procedure and has a different control resource set (CORESET), a different search space configuration, a different quasi-co-located QCL relationship, a different demodulation reference signal (DMRS) resource configuration, or a different multiple access signature than a PDCCH transmission of a RACH response message for a four-step RACH procedure.

27. A user equipment UE for wireless communication, the UE comprising: one or more memories having computer executable code stored thereon; as well as one or more processors, the one or more processors being coupled to the one or more memories and configured to execute the computer executable code and individually or collectively cause the UE to: Sending a random access channel RACH message to a base station BS for a two-step random access RA procedure, wherein the RACH message includes a RACH preamble transmission and a physical uplink shared channel PUSCH transmission; and Receiving a RACH response message from the BS, the RACH response message from the BS comprising a physical downlink control channel PDCCH transmission and a physical downlink shared channel PDSCH transmission, wherein receiving the RACH response message from the BS comprises: When the RACH message is for a contention-free random access CFRA two-step RA procedure: monitoring the PDCCH transmission of the RACH response message in a UE-specific search space USS; descrambling a cyclic redundancy check CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a UE-specific cell radio network temporary identifier C-RNTI or a UE-specific message B msgB RNTI; and monitoring the PDSCH transmission of the RACH response message based on the PDCCH transmission of the RACH response message; and When the RACH message is for contention-based random access (CBRA) two-step RA procedure: monitoring the PDCCH transmission of the RACH response message in a common search space CSS; descrambling the CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a group-specific RNTI; and The PDSCH transmission of the RACH response message is monitored based on the PDCCH transmission of the RACH response message, wherein the PDSCH transmission includes a UE-specific RNTI or a msgB RNTI.

28. A base station BS for wireless communication, the BS comprising: one or more memories having computer executable code stored thereon; as well as one or more processors coupled to the one or more memories and configured to execute the computer executable code and individually or collectively cause the BS to: receiving a random access channel (RACH) message from a user equipment (UE) for a two-step random access (RA) procedure, the RACH message including a RACH preamble transmission and a physical uplink shared channel (PUSCH) transmission; and Sending a RACH response message to the UE in a common search space CSS, where the RACH response message includes a physical downlink control channel PDCCH transmission and a physical downlink shared channel PDSCH transmission, wherein sending the RACH message to the UE includes: When the RACH message is for a contention-free random access CFRA two-step RA procedure: scrambling a cyclic redundancy check CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a UE-specific cell radio network temporary identifier C-RNTI or a UE-specific message B msgB RNTI; sending the PDCCH transmission of the RACH response message to the UE in a UE-specific search space USS; and sending the PDSCH transmission of the RACH response message to the UE based on the PDCCH transmission of the RACH response message; and When the RACH message is for contention-based random access (CBRA) two-step RA procedure: scrambling the CRC associated with the PDCCH transmission of the RACH response message, wherein the CRC is masked by a group-specific RNTI; sending the PDCCH transmission of the RACH response message in a common search space CSS; and The PDSCH transmission of the RACH response message is sent to the UE based on the PDCCH transmission of the RACH response message, wherein the PDSCH transmission of the RACH response message includes a UE-specific RNTI or a msgB RNTI.

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