SRS sent by MSG4ACK

Abstract

Certain aspects of the present disclosure provide techniques for transmitting a sounding reference signal (SRS) by a random access channel (RACH) acknowledgement (ACK) (e.g., after Msg4). An example method of a user equipment (UE) includes receiving a first downlink RACH message, receiving a second downlink RACH message after the first downlink RACH message, receiving signaling indicating that the UE is to transmit an SRS after the second downlink RACH message, and transmitting the SRS after the second downlink RACH message in accordance with the indication.

Description

[0001] Priority requirements

[0002] This application claims priority to U.S. Nonprovisional Application No. 17 / 150,885, filed January 15, 2021, and U.S. Provisional Application No. 63 / 092,891, filed October 16, 2020. The entire contents of each of these applications are expressly incorporated herein by reference, as if fully set forth below, and for all applicable purposes. Technical Field

[0003] Various aspects of this disclosure relate to wireless communication, and more specifically, to techniques for transmitting probe reference signals (SRS). Background Technology

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunications services, such as telephone, video, data, messaging, and broadcasting. These wireless communication systems can employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access systems include, to name a few, 3GPP Long Term Evolution (LTE) systems, LTE-A Advanced 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.

[0005] To provide a common protocol enabling different wireless devices to communicate at the city, country, region, and even global levels, these multiple access technologies have been adopted in various telecommunications standards. New radios (such as 5G NR) are an example of emerging telecommunications standards. NR is a set of enhancements to the LTE mobile standard issued by 3GPP. NR aims to better support mobile broadband internet access by improving spectrum efficiency, reducing costs, improving service, utilizing new spectrum, and using OFDMA with cyclic prefix (CP) on both downlink (DL) and uplink (UL) to better integrate with other open standards. To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0006] However, with the continued growth in demand for mobile broadband access, there is a need for further improvements to NR and LTE technologies. Preferably, these improvements should be applicable to other multiple access technologies and telecommunications standards that employ these technologies. Summary of the Invention

[0007] The systems, methods, and apparatus of this disclosure each have several aspects, and no single aspect is solely responsible for its desired properties. Without limiting the scope of this disclosure as set forth in the appended claims, some features will now be briefly discussed. After considering this discussion, and especially after reading the section entitled "Detailed Description," one will understand how the features of this disclosure can provide advantages, such as improved coverage enhancements in random access procedures.

[0008] Some aspects provide a method for wireless communication by a user equipment (UE). The method includes receiving a first downlink random access channel (RACH) message, receiving a second downlink RACH message after the first downlink RACH message, receiving signaling instructing the UE to transmit a sounding reference signal (SRS) after the second downlink RACH message, and transmitting the SRS according to the instruction after the second downlink RACH message.

[0009] Some aspects provide a method for wireless communication by a network entity. The method includes sending a first downlink RACH message to a UE, sending a second downlink RACH message to the UE after the first downlink RACH message, signaling the UE to an indication that the UE will send an SRS after the second downlink RACH message, and monitoring the SRS transmission from the UE after the second downlink RACH message according to the indication.

[0010] Some aspects provide an apparatus for wireless communication by a user equipment (UE). The apparatus includes a memory and at least one receiver coupled to the memory, the memory and the at least one processor being configured to: receive a first downlink random access channel (RACH) message, receive a second downlink RACH message after the first downlink RACH message, receive signaling instructing the UE to transmit a sounding reference signal (SRS) after the second downlink RACH message, and transmit the SRS according to the instruction after the second downlink RACH message.

[0011] Some aspects provide an apparatus for wireless communication by a network entity. The apparatus includes a memory and at least one receiver coupled to the memory, the memory and the at least one processor being configured to: send a first downlink RACH message to a UE; send a second downlink RACH message to the UE after the first downlink RACH message; signal the UE to an indication that the UE will send an SRS message after the second downlink RACH message; and monitor SRS transmissions from the UE after the second downlink RACH message according to the indication.

[0012] Some aspects provide an apparatus for wireless communication by a user equipment (UE). The apparatus includes components for receiving a first downlink random access channel (RACH) message, components for receiving a second downlink RACH message after the first downlink RACH message, components for receiving signaling instructing the UE to transmit a sounding reference signal (SRS) after the second downlink RACH message, and components for transmitting the SRS after the second downlink RACH message according to the instruction.

[0013] Some aspects provide an apparatus for wireless communication by a network entity. The method includes components for sending a first downlink RACH message to a UE, components for sending a second downlink RACH message to the UE after the first downlink RACH message, components for signaling to the UE an indication that the UE will send an SRS message after the second downlink RACH message, and components for monitoring SRS transmissions from the UE after the second downlink RACH message according to the indication.

[0014] Some aspects provide a computer-readable medium having stored thereon instructions for wireless communication by a user equipment (UE). The instructions include instructions for performing the following operations: receiving a first downlink random access channel (RACH) message; receiving a second downlink RACH message after the first downlink RACH message; receiving signaling instructing the UE to transmit a sounding reference signal (SRS) after the second downlink RACH message; and transmitting the SRS after the second downlink RACH message according to the instruction.

[0015] Some aspects provide a computer-readable medium having stored thereon instructions for wireless communication by a network entity. The instructions include instructions for performing the following operations: sending a first downlink RACH message to a UE; sending a second downlink RACH message to the UE after the first downlink RACH message; signaling the UE to an indication that the UE will send an SRS message after the second downlink RACH message; and monitoring SRS transmissions from the UE after the second downlink RACH message according to the indication.

[0016] Various aspects of this disclosure provide components, apparatus, processors, and computer-readable media for performing the methods described herein.

[0017] To achieve the foregoing and related results, one or more aspects include the features fully described below and specifically pointed out in the claims. The following description and drawings illustrate certain illustrative features of one or more aspects in detail. However, these features indicate only a few of the various ways in which the principles of each aspect can be employed. Attached Figure Description

[0018] To gain a more detailed understanding of the foregoing features of this disclosure, a more specific description of the above brief overview can be provided by referring to various aspects (some of which are illustrated in the accompanying drawings). However, it should be noted that the drawings illustrate only certain typical aspects of this disclosure and should therefore not be considered as limiting its scope, as the description may allow for other equivalent aspects.

[0019] Figure 1 This is a block diagram conceptually illustrating an example telecommunications system according to certain aspects of this disclosure.

[0020] Figure 2 This is a block diagram conceptually illustrating the design of an example base station (BS) and user equipment (UE) according to certain aspects of this disclosure.

[0021] Figure 3 An example of a frame format for a telecommunications system is shown, according to certain aspects of this disclosure.

[0022] Figure 4 This is a timing diagram illustrating an example four-step RACH process according to certain aspects of this disclosure.

[0023] Figure 5 This is a timing diagram illustrating an example two-step RACH process according to certain aspects of this disclosure.

[0024] Figure 6 This is a diagram illustrating example functionality of a lightweight (RedCap) UE according to certain aspects of this disclosure.

[0025] Figure 7 Example operations for wireless communication by a UE are shown according to certain aspects of this disclosure.

[0026] Figure 8 Example operations for wireless communication by a network entity are shown according to certain aspects of this disclosure.

[0027] Figure 9 An example RACH procedure with probe reference signal (SRS) transmission according to certain aspects of this disclosure is shown.

[0028] Figure 10 A communication device is shown that may include various components configured to perform operations for use with the techniques disclosed herein according to various aspects of this disclosure.

[0029] Figure 11 A communication device is shown that may include various components configured to perform operations for use with the techniques disclosed herein according to various aspects of this disclosure.

[0030] For ease of understanding, the same reference numerals are used where possible to denote the same elements common in the figures. Elements disclosed in one aspect are intended to be usefully applied in other aspects without specific description. Detailed Implementation

[0031] This disclosure relates to various aspects of wireless communication, and in particular, provides techniques for transmitting a sounding reference signal (SRS) by random access channel (RACH) acknowledgment (ACK) (e.g., before or after the random access channel (RACH) acknowledgment (ACK)). For example, the SRS can be provided by a method for a 4-step RACH process (such as... Figure 4 Msg2, Msg4 and / or Msg4 physical downlink control channel indications (as shown).

[0032] Depending on certain aspects, RACH messages (e.g., Msg 2, Msg 4, and / or Msg 4PDCCH) can trigger the UE to send an SRS. For example, such a RACH message may include an indication for the UE to send an SRS (e.g., via SRS authorization). This may cause the UE to send an SRS by a Msg 4ACK message (e.g., before or after the Msg 4ACK message).

[0033] SRS transmissions made in this early stage, before the Radio Resource Control (RRC) connection is established, can enhance performance and the overall user experience. For example, SRS transmissions made during the RACH process can help the gNB perform uplink timing tracking, beam management, and / or link adaptation during the RACH process. Performing these functions during the RACH process (rather than waiting until after the RRC connection is established) allows for faster optimization of communications.

[0034] The following description provides examples and is not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the elements discussed without departing from the scope of this disclosure. Various examples may be appropriately omitted, substituted, or added to various procedures or components. For example, methods may be performed in a different order than those described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined in some other examples. For instance, an apparatus or method may be implemented using any number of aspects set forth herein. Moreover, the scope of this disclosure is intended to cover such apparatuses or methods practiced using structures, functions, or structures and functions other than or different from the aspects of this disclosure set forth herein. It should be understood that any aspect of this disclosure may be embodied by one or more elements of the claims. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

[0035] The technologies described in this article can be used in various wireless communication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other networks. The terms "network" and "system" are often used interchangeably. CDMA networks can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other CDMA variants. cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks can 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 the Universal Mobile Telecommunications System (UMTS).

[0036] New Radio (NR) is an emerging wireless communication technology being developed in conjunction with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are versions of UMTS using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called the 3rd Generation Partnership Project (3GPP). cdma2000 and UMB are described in documents from an organization called the 3rd Generation Partnership Project 2 (3GPP2). The technologies described herein can be used in the aforementioned wireless network and radio technologies, as well as other wireless network and radio technologies. For clarity, although terms commonly associated with 3G and / or 4G wireless technologies may be used to describe aspects herein, aspects of this disclosure can be applied to other generation-based communication systems, such as 5G and later technologies, including NR technology.

[0037] New radio (NR) access (e.g., 5G technology) can support a variety of wireless communication services, such as enhanced mobile broadband (eMBB) for wide bandwidth (e.g., 80 MHz or higher), millimeter wave (mmW) for high carrier frequencies (e.g., 25 GHz or higher), massive machine-type communication (mMTC) for non-backward-compatible MTC technologies, and / or mission-critical ultra-reliable low-latency communication (URLLC). These services may have latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet their respective quality of service (QoS) requirements. Furthermore, these services may coexist in the same subframe.

[0038] Example wireless communication system

[0039] Figure 1 An example wireless communication network 100 in which various aspects of this disclosure can be implemented is shown. For example, according to the various aspects discussed herein, UE 120 can be configured with an SRS having a RACH component 199 to implement... Figure 7 Operation 700 involves sending a sounding reference signal (SRS) using a random access channel (RACH) acknowledgment (ACK) (e.g., before or after the RACH acknowledgment) (e.g., after Msg4). Similarly, base station 110 can be configured with an SRS having a RACH component 198 to perform this operation. Figure 8 Operation 800 is used to instruct the UE (e.g., to perform...) Figure 7 Operation 700) sends SRS by RACH ACK (e.g., before or after RACH ACK) (e.g., after Msg4) and monitors such SRS transmission.

[0040] like Figure 1 As shown, the wireless communication network 100 may include multiple base stations (BS) 110 and other network entities. A BS may be a station communicating with a user equipment (UE). Each BS 110 may provide communication coverage for a specific geographic area. In 3GPP, depending on the context in which the term is used, the term "cell" may refer to the coverage area of ​​a Node B (NB) and / or the NB subsystem serving that coverage area. In NR systems, the term "cell" and next-generation Node B (gNB or gNodeB), NR BS, 5G NB, access point (AP), or transmit / receive point (TRP) are used interchangeably. In some examples, the cell may not necessarily be fixed, and the geographic area of ​​the cell may move depending on the location of the mobile BS. In some examples, base stations may interconnect with each other and / or with one or more other base stations or network nodes (not shown) in the wireless communication network 100 via various types of backhaul interfaces (such as direct physical connections, wireless connections, virtual networks, or the like using any suitable delivery network).

[0041] Typically, any number of wireless networks can be deployed in a given geographical area. Each wireless network can support a specific Radio Access Technology (RAT) and can operate on one or more frequencies. A RAT can also be referred to as a radio technology, air interface, etc. A frequency can also be referred to as a carrier, subcarrier, frequency channel, tone, subband, etc. Each frequency can support a single RAT in a given geographical area to avoid interference between wireless networks using different RATs. In some cases, NR or 5GRAT networks can be deployed.

[0042] A BS can provide communication coverage to macrocells, picocells, femtocells, and / or other types of cells. A macrocell can cover a relatively large geographic area (e.g., a radius of several kilometers) and allow unrestricted access for UEs with service subscriptions. A picocell can cover a relatively small geographic area and allow unrestricted access for UEs with service subscriptions. A femtocell can cover a relatively small geographic area (e.g., a home) and allow restricted access for UEs associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in a home, etc.). A BS used for macrocells can be called a macro BS. A BS for picocells can be called a pico BS. A BS for femtocells can be called a femto BS or a home BS. Figure 1In the example shown, BS 110a, 110b, and 110c can be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x can be a pico BS for pico cell 102x. BS 110y and 110z can be femto BSs for femto cells 102y and 102z, respectively. A BS can support one or more (e.g., three) cells.

[0043] The wireless communication network 100 may also include relay stations. A relay station is a station that receives data and / or other information transmissions from an upstream station (e.g., a BS or a UE) and transmits the data and / or other information to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that relays transmissions from other UEs. Figure 1 In the example shown, relay station 110r can communicate with BS110a and UE 120r to facilitate communication between BS 110a and UE 120r. A relay station can also be referred to as a relay BS, repeater, etc.

[0044] The wireless communication network 100 can be a heterogeneous network, comprising different types of base stations (BSs), such as macro BSs, pico BSs, femto BSs, repeaters, etc. These different types of BSs can have different transmit power levels, different coverage areas, and different effects on interference in the wireless communication network 100. For example, a macro BS can have a high transmit power level (e.g., 20 watts), while a pico BS, femto BS, and repeaters can have a lower transmit power level (e.g., 1 watt).

[0045] The wireless communication network 100 can support synchronous or asynchronous operation. For synchronous operation, the base stations (BSs) can have similar frame timings, and transmissions from different BSs can be approximately aligned over time. For asynchronous operation, the BSs can have different frame timings, and transmissions from different BSs can be misaligned over time. The techniques described herein can be used for both synchronous and asynchronous operations.

[0046] Network controller 130 can be coupled to a group of BSs and can provide coordination and control for these BSs. Network controller 130 can communicate with BS 110 via backhaul. BS 110 can also communicate with each other directly or indirectly, for example, via wireless or wired backhaul.

[0047] UEs 120 (e.g., 120x, 120y, etc.) may be distributed throughout the wireless communication network 100, and each UE may be fixed or mobile. A UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smartphone, 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, biosensor / device, wearable device (such as smartwatch, smart clothing, smart glasses, smart bracelet), smart jewelry (e.g., smart ring, smart bracelet, etc.), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, GPS device, or any other suitable device configured to communicate via wireless or wired media. 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, instruments, monitors, location tags, etc., which can communicate with the BS, another device (e.g., a remote device), or other entities. For example, a wireless node can provide connectivity to or to a network (e.g., a wide area network such as the Internet or cellular networks) via wired or wireless communication links. Some UEs can be considered Internet of Things (IoT) devices; they can be narrowband IoT (NB-IoT) devices.

[0048] Some wireless networks (e.g., LTE) utilize Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and Single-Carrier Frequency Division Multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, often referred to as tones, bins, etc. Each subcarrier can be modulated with data. Typically, modulation symbols are transmitted in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the subcarrier spacing could be 15 kHz, and the minimum resource allocation (called a "resource block" (RB)) could be 12 subcarriers (or 180 kHz). Therefore, for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, the nominal Fast Fourier Transform (FFT) size could be 128, 256, 512, 1024, or 2048, respectively. System bandwidth can also be divided into subbands. For example, a subband can cover 1.08MHz (i.e., 6 resource blocks), and there can be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10, or 20MHz, respectively.

[0049] While the aspects of the examples described herein can be associated with LTE technology, aspects of this disclosure can be applied to other wireless communication systems, such as NR. NR can use OFDM with CP on both the uplink and downlink, and includes support for half-duplex operation using TDD. Beamforming can be supported, and beam direction can be dynamically configured. MIMO transmission with pre-decoding can also be supported. MIMO configuration in DL can support up to 8 transmit antennas, multi-layer DL transmission of up to 8 streams, and up to 2 streams per UE. Multi-layer transmission of up to 2 streams per UE can be supported. Aggregation of multiple cells with up to 8 serving cells can be supported.

[0050] In some examples, access to the air interface can be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication between some or all devices and equipment within its service area or cell. The scheduling entity can be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize the resources allocated by the scheduling entity. The base station is not the only entity that can act as a scheduling entity. In some examples, a UE can act as a scheduling entity and can schedule resources for one or more subordinate entities (e.g., one or more other UEs), and other UEs can use the resources scheduled by the UE for wireless communication. In some examples, a UE can act as a scheduling entity in a point-to-point (P2P) network and / or a mesh network. In the mesh network example, in addition to communicating with a scheduling entity, UEs can also communicate directly with each other.

[0051] exist Figure 1 In the diagram, a solid line with a double arrowhead indicates a desired transmission between the UE and the serving BS, which is a BS designated to serve the UE on the downlink and / or uplink. A thin dashed line with a double arrowhead indicates interference transmission between the UE and the BS.

[0052] Figure 2 Some example aspects of a base station (BS) 102 and a user equipment (UE) 104 are depicted. Typically, the BS 102 includes various processors (e.g., 220, 230, 238, and 240), antennas 234a-t, transceivers 232a-t, and other aspects for transmitting data (e.g., source data 212) and receiving data (e.g., data sink 239). For example, the BS 102 can transmit and receive data between itself and the UE 104.

[0053] In the depicted example, BS 102 includes a controller / processor 240, which includes an SRS with a RACH component 241. In some cases, the SRS with the RACH component 241 can be configured to implement... Figure 1 The RACH component 199's SRS, and performs regarding Figure 8 Operations involving depiction and description.

[0054] UE 104 typically includes various processors (e.g., 258, 264, 266, and 280), antennas 252a-r, transceivers 254a-r, and other aspects for transmitting data (e.g., source data 262) and receiving data (e.g., data sink 260).

[0055] In the depicted example, UE 104 includes a controller / processor 280, which includes an SRS with a RACH component 281. In some cases, the SRS with the RACH component 281 can be configured to implement... Figure 1 The RACH component 198's SRS, and performs regarding Figure 7 Operations involving depiction and description.

[0056] At BS 102, the transmitting processor 220 can receive data from the data source 212 and control information from the controller / processor 240. The control information can be used for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid ARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), Group Common PDCCH (GCPDCCH), etc. Data can be used for the Physical Downlink Shared Channel (PDSCH), etc.

[0057] The Media Access Control (MAC)-Control Element (MAC-CE) is a MAC layer communication structure used for exchanging control commands between wireless nodes. The MAC-CE can be carried in a shared channel, such as the Physical Downlink Shared Channel (PDSCH), Physical Uplink Shared Channel (PUSCH), or Physical Sidelink Shared Channel (PSSCH).

[0058] Processor 220 can process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmitter processor 220 can also generate reference symbols, such as those for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS).

[0059] The transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., pre-decoding) on ​​data symbols, control symbols, and / or reference symbols (if applicable), and can provide an output symbol stream to the modulators (MODs) in transceivers 232a-232t. Each modulator in transceivers 232a-232t can process its own output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signal from the modulators in transceivers 232a-232t can be transmitted via antennas 234a-234t respectively.

[0060] At UE 104, antennas 252a-252r can receive downlink signals from BS 102 and can provide the received signals to demodulators (DEMODs) in transceivers 254a-254r respectively. Each demodulator in transceivers 254a-254r can modulate (e.g., filter, amplify, down-convert, and digitize) the individually received signal to obtain an input sample. Each demodulator can further process the input sample (e.g., for OFDM, etc.) to obtain the received symbol.

[0061] The MIMO detector 256 can obtain received symbols from all demodulators in transceivers 254a-254r, perform MIMO detection on the received symbols if applicable, and provide the detected symbols. The receiver processor 258 can process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 104 to data sink 260, and provide decoding control information to controller / processor 280.

[0062] On the uplink, at UE 104, the transmit processor 264 can receive and process data from data source 262 (e.g., for the Physical Uplink Shared Channel (PUSCH)) and control information from the controller / processor 280 (e.g., for the Physical Uplink Control Channel (PUCCH)). The transmit processor 264 can also generate reference symbols for reference signals (e.g., for Sounding Reference Signals (SRS)). Symbols from the transmit processor 264 can be pre-decoded (if applicable) by the TX MIMO processor 266, then further processed by modulators in transceivers 254a-254r (e.g., SC-FDM, etc.), and transmitted to BS 102.

[0063] At BS 102, uplink signals from UE 104 can be received by antennas 234a-t, processed by demodulators in transceivers 232a-232t, detected by MIMO detector 236 (if applicable), and further processed by receiver processor 238 to obtain decoded data and control information transmitted by UE 104. Receiver processor 238 can provide the decoded data to data sink 239 and the decoded control information to controller / processor 240.

[0064] Memory 242 and 282 can store data and program code for BS 102 and UE 104, respectively.

[0065] Scheduler 244 can schedule UE to transmit data on the downlink and / or uplink.

[0066] Antenna 252, processors 266, 258, 264 and / or controller / processor 280 of UE 104, and / or antenna 234, processors 220, 230, 238 and / or controller / processor 240 of BS 102 can be used to perform the various techniques and methods described herein.

[0067] In LTE, the basic transmission time interval (TTI), or packet duration, is a 1ms subframe. In NR, a subframe is still 1ms, but the basic TTI is called a slot. A subframe contains a variable number of slots (e.g., slots 1, 2, 4, 8, 16…), depending on the subcarrier spacing. NR RBs are 12 consecutive frequency subcarriers. NR can support a basic subcarrier spacing of 15kHz, and other subcarrier spacings can be defined relative to the basic subcarrier spacing, such as 30kHz, 60kHz, 120kHz, 240kHz, etc. Symbol and slot lengths scale with the subcarrier spacing. The CP length also depends on the subcarrier spacing.

[0068] Figure 3This is a diagram illustrating an example of frame format 300 for NR. The transmission timeline for each of the downlink and uplink can be divided into units of radio frames. Each radio frame can have a predetermined duration (e.g., 10 ms) and can be divided into 10 subframes with indices 0 to 9, each subframe being 1 ms long. Depending on the subcarrier spacing, each subframe can include a variable number of time slots. Depending on the subcarrier spacing, each time slot can include a variable number of symbol periods (e.g., 7 or 14 symbols). The symbol periods in each time slot can be assigned an index. A micro-time slot, which may be referred to as a sub-time slot structure, is a transmission time interval with a duration less than that of a time slot (e.g., 2, 3, or 4 symbols).

[0069] Each symbol within a time slot can indicate the link direction used for data transmission (e.g., DL, UL, or a flexible link direction), and the link direction can be dynamically switched for each subframe. The link direction can be based on the time slot format. Each time slot can include DL / UL data as well as DL / UL control information.

[0070] In NR, a synchronization signal (SS) block is transmitted. The SS block includes the PSS, SSS, and double-symbol PBCH. The SS block can be transmitted at fixed time slot positions, such as... Figure 3 The symbols 0-3 are shown. The UE can use PSS and SSS for cell search and acquisition. PSS provides half-frame timing, and SS provides CP length and frame timing. PSS and SSS can provide cell identification. PBCH carries basic system information such as downlink system bandwidth, intra-radio frame timing information, SS burst group period, system frame number, etc. SS blocks can be organized into SS bursts to support beam scanning. Other system information, such as Residual Minimum System Information (RMSI), System Information Block (SIB), and Other System Information (OSI), can be transmitted on the Physical Downlink Shared Channel (PDSCH) in certain subframes. SS blocks can be transmitted up to sixty-four times; for example, for mmW, there can be up to sixty-four different beam directions. Up to sixty-four transmissions of SS blocks are called SS burst sets. SS blocks in an SS burst set are transmitted in the same frequency domain, while SS blocks in different SS burst sets can be transmitted at different frequency locations.

[0071] In some cases, two or more dependent entities (e.g., UEs) can communicate with each other using sidelink signaling. Real-world applications of such sidelink communication may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communication, Internet of Things (IoE) communication, IoT communication, mission-critical mesh, and / or various other suitable applications. Typically, sidelink signaling can refer to a signal transmitted from one dependent entity (e.g., UE1) to another dependent 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, licensed spectrum can be used to transmit sidelink signals (unlike wireless LANs that typically use unlicensed spectrum).

[0072] The UE can operate in various radio resource configurations, including configurations associated with transmitting pilots using a dedicated resource set (e.g., Radio Resource Control (RRC) dedicated state, etc.) or configurations associated with transmitting pilots using a common resource set (e.g., RRC common state, etc.). When operating in RRC dedicated state, the UE can select the dedicated resource set for transmitting pilot signals to the network. When operating in RRC common state, the UE can select the common resource set for transmitting pilot signals to the network. In either case, the pilot signals transmitted by the UE can be received by one or more network access devices, such as AN or DU or portions thereof. Each receiving network access device can be configured to receive and measure pilot signals transmitted on the common resource set, and also to receive and measure pilot signals transmitted on the dedicated resource set allocated to the UE, for which the network access device is a member of the network access device monitoring set for that UE. One or more of the receiving network access devices, or one or more CUs receiving measurements of pilot signals transmitted to them by the network access devices, can use these measurements to identify the serving cell for the UE, or to initiate a change of serving cell for one or more of the UEs.

[0073] Example RACH procedure

[0074] The Random Access Channel (RACH) is so named because it refers to a radio channel (medium) that can be shared by multiple UEs and used by UEs to (randomly) access the network for communication. For example, RACH can be used for call setup and network access for data transmission. In some cases, RACH can be used for initial network access when a UE switches from idle mode to active mode of a Radio Resource Control (RRC) connection, or when transitioning between RRC connection modes. Furthermore, RACH can be used for downlink (DL) and / or uplink (UL) data arrival when a UE is in RRC idle or RRC inactive mode, and when re-establishing a connection with the network.

[0075] Figure 4 Figure 400 illustrates a timing (or “call flow”) diagram of an example four-step RACH procedure according to certain aspects of this disclosure. A first message (MSG1) may be sent from UE 120 to BS 110 on the Physical Random Access Channel (PRACH). In this case, MSG1 may consist only of the RACH preamble. BS 110 may respond with a Random Access Response (RAR) message (MSG2), which may include an identifier (ID) of the RACH preamble, timing advance (TA), uplink grant, cell radio network temporary identifier (C-RNTI), and backoff indicator. As shown, MSG2 may include PDCCH communication, which includes control information for subsequent communication on the PDSCH. In response to MSG2, MSG3 is sent from UE 120 to BS 110 on the PUSCH. MSG3 may include one or more of the following: RRC connection request, tracking area update request, system information request, location fixation or location signal request, or scheduling request. BS 110 then responds with MSG 4, which may include a race-resolve message.

[0076] In some cases, a two-step RACH procedure can be supported to speed up access. As the name suggests, this two-step RACH procedure can effectively "fold" the four messages of a four-step RACH procedure into two messages.

[0077] Figure 5 This is a timing diagram 500 illustrating an example two-step RACH procedure according to certain aspects of this disclosure. A first enhanced message (msgA) can be sent from UE120 to BS110. In some aspects, msgA includes some or all of the information from MSG1 and MSG3 from the four-step RACH procedure, effectively combining MSG1 and MSG3. For example, msgA may include MSG1 and MSG3 multiplexed together, such as using time division multiplexing or frequency division multiplexing. In some aspects, msgA includes a RACH preamble and payload for random access. For example, the msgA payload may include the UE-ID and other signaling information (e.g., buffer status report (BSR)) or scheduling request (SR). BS110 may respond with a random access response (RAR) message (msgB) that can effectively combine the aforementioned MSG2 and MSG4. For example, msgB may include the ID of the RACH preamble, timing advance (TA), backoff indicator, contention resolution message, UL / DL authorization, and transmit power control (TPC) command.

[0078] In a two-step RACH process, msgA may include a RACH preamble and a payload. In some cases, the RACH preamble and payload may be sent at the same time as msgA.

[0079] The timing of random access message (msgA) transmission includes the timing of the msgA preamble (used for transmitting the preamble signal) and the timing of the msgA payload (used for transmitting the PUSCH). The transmission of the msgA preamble involves:

[0080] (1) Select the preamble sequence; and

[0081] (2) Select the timing of the preamble in the time / frequency domain (for transmitting the selected preamble sequence).

[0082] The msgA payload transmission involves:

[0083] (1) Constructing the Random Access Message Payload (DMRS / PUSCH); and

[0084] (2) Select one or more PUSCH resource units (PRUs) in the time / frequency domain to send the message (payload).

[0085] In some cases, the UE monitors SSB transmissions (issued by the gNB using different beams) that are associated with a limited set of time / frequency resources that define the RACH timing (RO) and PRUs. As will be described in more detail below, after detecting an SSB, the UE can select the RO and one or more PRUs associated with that SSB for msgA transmission. The limited set of ROs and PRUs helps reduce the base station's monitoring overhead (e.g., processing associated with performing blind decoding).

[0086] Due to certain characteristics, such as access speed and the ability to transmit relatively small amounts of data without the overhead of the entire four-step RACH process, a two-step RACH process is sometimes chosen instead of a four-step RACH procedure to establish a connection (when the four-step RACH message may be larger than the payload). For example, in the Industrial Internet of Things (I-IoT), lightweight (RedCap) UEs (such as...) Figure 6 As shown, a two-step RACH process can be performed to emit a small amount of sensor data.

[0087] 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 support the transmission of contention-based random access (CBRA) messages (e.g., msgA) within a limited range of payload sizes and a limited number of MCS levels.

[0088] Various technologies are likely to be the focus of current wireless communication standards. For example, Rel-15 and / or Rel-16 may focus on high-end smartphones (e.g., enhanced mobile broadband (eMBB)) and other vertical sectors such as ultra-reliable low-latency communication (URLLC) and / or vehicle-to-everything (V2X) communication. In some wireless communication standards (e.g., Rel-17 and later), there may be a strong desire for new radios (NR) to be scalable and deployed in a more efficient and economical way. Therefore, a new UE type with lightweight (RedCap) has been introduced. In particular, lightweight UEs can exhibit reduced peak throughput and lower latency and / or reliability requirements.

[0089] Therefore, some design goals for NR lightweight UEs may include scalable resource allocation, enhanced coverage in DL and / or UL, power savings in all RRC states, and / or coexistence with NR advanced UEs. For example... Figure 6 As shown, the NR-lightweight UE can be a smart wearable device, a sensor / camera, or any other device configured for relaxed Internet of Things (IoT) communications. Furthermore, the lightweight UE's functions and / or capabilities can overlap with those of Long Term Evolution (LTE) and / or 5G devices (e.g., advanced 5G devices). For example, the functions of a relaxed IoT device can overlap with those of a URLLC device, the functions of a smart wearable device can overlap with those of a Low Power Wide Area (LPWA) Massive Machine Type Communication (mMTC) device, and / or the functions of a sensor / camera can overlap with those of an eMBB device.

[0090] Example SRS after Msg 4 in the RACH process

[0091] This disclosure provides techniques for transmitting a sounding reference signal (SRS) by random access channel (RACH) acknowledgment (ACK) (e.g., before or after the random access channel acknowledgment) (e.g., after Msg 4 of the RACH procedure). For example, the SRS can be provided by a method for transmitting a sounding reference signal (SRS) in a 4-step RACH procedure (such as...). Figure 4 Msg2, Msg4 and / or Msg4 physical downlink control channel indications (as shown).

[0092] As mentioned above, supporting SRS transmission in this early stage, prior to the establishment of a Radio Resource Control (RRC) connection, can enhance performance and the overall user experience. For example, SRS transmission during the RACH process can help the gNB perform uplink timing tracking, beam management, and / or link adaptation, thereby increasing throughput more quickly after the RRC connection is established.

[0093] The technology proposed in this paper can be applied to various frequency bands used for NR.

[0094] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc., based on frequency / wavelength. In 5G NR, two initial operating bands have been designated as frequency ranges FR1 (410MHz-7.125GHz) and FR2 (24.25GHz-52.6GHz). It should be understood that although a portion of FR1 is greater than 6GHz, FR1 is often (interchangeably) referred to as the "sub-6GHz" band in various documents and articles. Similar naming issues sometimes arise with FR2; although different from the Extremely High Frequency (EHF) band (30GHz-300GHz) recognized as a "millimeter wave" band by the International Telecommunication Union (ITU), FR2 is often (interchangeably) referred to as the "millimeter wave" band in documents and articles.

[0095] The frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR studies have designated the operating bands of these mid-band frequencies as the frequency range designation FR3 (7.125 GHz – 24.25 GHz). Bands falling within FR3 can inherit FR1 and / or FR2 characteristics, and thus can effectively extend the features of FR1 and / or FR2 to mid-band frequencies. Furthermore, higher bands are currently being explored to extend 5G NR operation above 52.6 GHz. For example, three higher operating bands have been designated as the frequency range names FR4a or FR4-1 (52.6 GHz – 71 GHz), FR4 (52.6 GHz – 114.25 GHz), and FR5 (114.25 GHz – 300 GHz). Each of these higher bands falls within the EHF band.

[0096] In light of the foregoing, unless otherwise specifically stated, it should be understood that, as used herein, the terms "sub-6GHz," etc., can broadly refer to frequencies that may be less than 6GHz, frequencies within FR1, or frequencies that may include intermediate frequency bands. Furthermore, unless otherwise specifically stated, it should be understood that, as used herein, the terms "millimeter wave," etc., can broadly refer to frequencies that may include intermediate frequency bands, frequencies within FR2, FR4, FR4-a, or FR4-1 and / or FR5, or frequencies within the EHF band.

[0097] Physical RACH (PRACH), Msg2 Physical Downlink Control Channel (PDCCH), and Msg3 Physical Uplink Shared Channel (PUSCH) messages may encounter coverage issues. This is especially true for FR2 due to its sensitivity to directionality within this frequency range. In some implementations, beamforming is a method that may be employed to improve received signal power (e.g., by providing more beamforming gain to the beam). Beamforming can be performed at the gNB or UE for transmission or reception.

[0098] Various methods have been proposed for beam refinement at the gNB (e.g., based on receiving multiple copies of the uplink (UL) signal via different refined beams). For example, for receiving multiple copies of a PRACH via different refined beams, the refined beams used for transmitting Msg2 PDCCH (and Msg2) and receiving Msg3 can be selected. In some cases, the Channel State Information (CSI) Reference Signal (RS) (or other RS) can be scheduled by the Residual System Information (RMSI) PDCCH to aid beam refinement on the UE side. In some cases, transmitting a preloaded preamble or RS along with the transmission of Msg3 PUSCH can also contribute to beam refinement.

[0099] In New Radio (NR), SRS is used for uplink (UL) detection. In this case, SRS can be used to improve UL reception and / or DL ​​pre-decoding. A given SRS resource can be configured as aperiodic, periodic, or semi-persistent. Periodic resources are configured with slot-level periodicity and / or slot offset. Semi-persistent resources are configured with slot-level periodicity and / or slot offset.

[0100] In some cases, semi-persistent resources can be activated / deactivated by a Media Access Control (MAC) element (CE), and multiple SRS resources can be activated / deactivated with a single message. Aperiodic resources are configured without slot-level periodicity and slot offset. For aperiodic resources, the Downlink Control Information (DCI) (e.g., scheduling downlink (DL) and / or UL) includes an SRS request field (e.g., 2 bits). In some cases, a group common (GC) DCI can be used to trigger a set of aperiodic SRS resources.

[0101] Furthermore, one or more aperiodic SRS resources can be triggered by DCI on a per-set basis, and multiple SRS resources can be triggered with a single DCI message. Additionally, the code point of the SRS request field in the DCI can be mapped to one or more SRS resource sets, along with a state for that field, which can be used to select at least one from the configured SRS resources. It should be noted that for periodic / semi-persistent resources, different resources can have different periodicities and / or slot offsets.

[0102] In some cases, a UE can be configured with one or more (e.g., K≥1) SRS resources, where a given X-port SRS resource spans N=1, 2, or 4 adjacent symbols within a time slot (e.g., all X ports are mapped to each symbol of the resource) and / or (for controlling the bandwidth allocated to the SRS) C. SRS and B SRS It can be configured in a UE-specific manner. For slot periodicity, various numbers of slots can be supported for all types of SCS (e.g., 1, 2, 5, 10, 20, 40, 80, 160, 320, 640, 1280 or 2560 slots).

[0103] In addition, NR supports configuring X-port (e.g., X≤4) SRS resources that span N (e.g., N=1, 2, or 4) adjacent Orthogonal Frequency Division Multiplexing (OFDM) symbols within the same time slot. In some cases, gNB will configure SRS resources in the time domain only through UE-specific parameters (e.g., via SRS SlotConfig, SRS ResourceMapping).

[0104] When only repetition is configured, X ports are mapped to each symbol and within the resource, and each of the X ports is mapped to the same set of subcarriers in the same Physical Resource Block (PRB) set of N SRS symbols. When only frequency hopping is configured, X ports are mapped to potentially different sets of subcarriers in each OFDM symbol of the resource (e.g., depending on the frequency hopping mode).

[0105] However, aspects of this disclosure provide further coverage enhancements to RACH messages during RACH procedures, based on SRS transmission via beamfinding and / or enhanced CSI. SRS configuration can occur via RRC signaling, in which case SRS transmission begins after the RRC connection is established. However, certain aspects of this disclosure provide for the UE to transmit SRS prior to the RRC connection. For example, the UE can be configured to transmit SRS after receiving a downlink RACH message (e.g., Msg 4) and by RACH ACK (e.g., before or after RACH ACK). In one example, the UE can receive an indication of SRS (e.g., via Msg 2, Msg 4, and / or Msg4 PDCCH). In another example, the UE can also determine the resources for SRS based on the resources of the RACH ACK message.

[0106] Figure 7 An example operation 700 for wireless communication according to certain aspects of this disclosure is shown. Operation 700 can be performed, for example, by a UE (e.g., UE 120a in wireless communication network 100) to transmit SRS (e.g., after Msg 4).

[0107] Operation 700 begins at 702 to receive the first downlink RACH message.

[0108] At 704, the UE receives the second downlink RACH message after the first downlink RACH message.

[0109] At 706, the UE receives a signaling instruction indicating that the UE will send SRS after the second downlink RACH message.

[0110] For example, the UE can receive a first downlink RACH message, a second downlink RACH message, and an instruction for the UE to transmit via... Figure 2 The UE 104 and / or shown Figure 10 The device shown transmits SRS signaling via one or more antennas and receiver / transceiver components.

[0111] At 708, the UE, according to this instruction, sends the SRS after the second downlink RACH message. For example, the UE can via... Figure 2 The UE 104 and / or shown Figure 10 The device shown uses one or more antennas and receiver / transceiver components to transmit SRS.

[0112] Figure 8 An example operation 800 for wireless communication performed by a network entity is shown, and can be considered as... Figure 7 This is a supplement to operation 700. For example, operation 800 can be executed by BS 110 to enable execution. Figure 8 The UE of Operation 800 is configured to send SRS (for example, after Msg 4).

[0113] Operation 800 begins at 802 by sending the first downlink RACH message to the UE.

[0114] At position 804, the network entity sends a second downlink RACH message to the UE after the first downlink RACH message.

[0115] At 806, the network entity signals to the UE that the UE will send an instruction for SRS after the second downlink RACH message.

[0116] For example, a network entity can send a first downlink RACH message, a second downlink RACH message, and an instruction to the UE to use the network. Figure 2 BS 102 and / or shown Figure 11 The device shown transmits SRS signaling via one or more antennas and receiver / transceiver components.

[0117] At point 808, the network entity, following this instruction, monitors SRS transmissions from the UE after the second downlink RACH message. For example, the network entity can do so via... Figure 2 BS 102 and / or shown Figure 11 The device shown uses one or more antennas and receiver / transceiver components to monitor SRS.

[0118] You can refer to this. Figure 9 To understand the call flow chart 900 Figure 7 and 8 Operations 700 and 800, Figure 9 An example of how to trigger SRS during a four-step RACH process is shown. In some respects, UE 120 can send SRS after receiving Msg 4 and, for example, before or after the Msg 4ACK message.

[0119] As shown in the figure, Msg 2, Msg 4, and / or Msg 4PDCCH can trigger UE 120 to send an SRS. For example, Msg 2, Msg 4, and / or Msg 4PDCCH may include an indication for UE 120 to send an SRS (e.g., via SRS authorization). Therefore, as shown in the figure, after Msg 4, UE 120 sends an SRS together with a Msg 4ACK message (e.g., before or after the Msg 4ACK message). As shown in the figure, the SRS is sent after receiving Msg 4 and before Msg 4ACK. Although not shown, in some cases, the SRS may be sent after Msg 4 and Msg 4ACK.

[0120] In some respects, SRS transmission can be performed based on configuration parameters. For example, configuration parameters for SRS transmission can be predefined in standard specifications. In some cases, configuration parameters can be indicated in the downlink message instructing the UE to transmit SRS. For example, configuration parameters can be indicated in Msg2 and / or the MAC CE delivered by Msg4.

[0121] The resources for SRS can be determined by the UE in various ways. For example, the resources for SRS can be based on the resources of Msg4ACK. That is, the UE can determine the resources for SRS such that the resources for SRS precede or follow the resources of Msg4ACK. For example, the UE can decode Msg 4 to determine the resources of Msg 4ACK, and thus subsequently know which resources to use for SRS transmission. As another example, the resources for SRS transmission can be determined according to rules specified in the standard specification and / or additional parameters in the Msg4 MAC CE.

[0122] In some respects, if a resource is indicated by a bit field in Msg 4 or Msg 4PDCCH, a certain number of bits in the bit field can indicate the number of predefined options or rules that the UE can use to determine the standard specification of the SRS resource. For example, 3 bits in the bit field can indicate up to 8 predefined options or rules.

[0123] In some cases, the SRS bandwidth and / or SRS frequency allocation can be indicated in Msg4 (e.g., MACCE delivered by Msg4) and / or Msg4PDCCH (e.g., via bit fields in Msg4 PDCCH). In some aspects, SRS can be indicated and / or determined as a single transmission, or SRS can be transmitted at a given periodicity.

[0124] In some cases, the scheduling of SRS transmissions can be valid / usable until an RRC connection is established. That is, for example, once an RRC connection is established, SRS transmission resources, parameters, and / or periodicity can be updated via RRC signaling.

[0125] Figure 10 A communication device 1000 is shown, which may include operations configured to perform the techniques disclosed herein, such as Figure 7 The operation illustrated herein includes various components (e.g., corresponding to component plus functional components). Communication device 1000 includes a processing system 1002 coupled to transceiver 1008. Transceiver 1008 is configured to transmit and receive signals, such as the various signals described herein, for communication device 1000 via antenna 1010. Processing system 1002 can be configured to enable communication device 1000 to perform processing functions, including processing signals received and / or to be transmitted by communication device 1000.

[0126] The processing system 1002 includes a processor 1004 coupled to a computer-readable medium / memory 1012 via a bus 1006. In some aspects, the computer-readable medium / memory 1012 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1004, cause the processor 1004 to perform... Figure 7The operations shown may be other operations used to perform the various techniques discussed herein. In some aspects, the computer-readable medium / memory 1012 stores code 1014 for receiving a first downlink RACH message; code 1016 for receiving a second downlink RACH message after the first downlink RACH message; code 1018 for receiving signaling instructing the UE to send an SRS after the second downlink RACH message; and code 1020 for sending an SRS after the second downlink RACH message according to the instruction. In some aspects, the processor 1004 has circuitry configured to implement the code stored in the computer-readable medium / memory 1012. The processor 1004 includes circuitry 1022 for receiving the first downlink RACH message; circuitry 1024 for receiving a second downlink RACH message after the first downlink RACH message; circuitry 1026 for receiving signaling instructing the UE to send an SRS after the second downlink RACH message; and circuitry 1028 for sending an SRS after the second downlink RACH message according to the instruction.

[0127] Figure 11 A communication device 1100 is shown, which may include operations configured to perform the techniques disclosed herein, such as Figure 8 The operation shown herein includes various components (e.g., corresponding to component plus functional components). Communication device 1100 includes a processing system 1102 coupled to transceiver 1108. Transceiver 1108 is configured to transmit and receive signals, such as the various signals described herein, for communication device 1100 via antenna 1110. Processing system 1102 can be configured to enable communication device 1100 to perform processing functions, including processing signals to be received and / or transmitted by communication device 1100.

[0128] The processing system 1102 includes a processor 1104 coupled to a computer-readable medium / memory 1112 via a bus 1106. In some aspects, the computer-readable medium / memory 1112 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1104, cause the processor 1104 to perform... Figure 8The operations shown may be other operations used to perform the various techniques discussed herein. In some aspects, the computer-readable medium / memory 1112 stores code 1114 for sending a first downlink RACH message to the UE; code 1116 for sending a second downlink RACH message to the UE after the first downlink RACH message; code 1118 for signaling to the UE an indication that an SRS will be sent after the second downlink RACH message; and code 1120 for monitoring the transmission of SRS from the UE after the second downlink RACH message according to the indication. In some aspects, the processor 1104 has circuitry configured to implement the code stored in the computer-readable medium / memory 1112. The processor 1104 includes circuitry 1122 for sending a first downlink RACH message to the UE; circuitry 1124 for sending a second downlink RACH message to the UE after the first downlink RACH message; circuitry 1126 for signaling to the UE an indication that the UE will send an SRS message after the second downlink RACH message; and circuitry 1128 for monitoring SRS transmission from the UE after the second downlink RACH message according to the indication.

[0129] Example

[0130] Aspect 1: A method for performing wireless communication by a user equipment (UE), comprising receiving a first downlink random access channel (RACH) message, receiving a second downlink RACH message after the first downlink RACH message, receiving signaling instructing the UE to transmit a sounding reference signal (SRS) after the second downlink RACH message, and transmitting the SRS after the second downlink RACH message according to the instruction.

[0131] Aspect 2: According to the method of aspect 1, wherein the indication is provided in the first downlink RACH message.

[0132] Aspect 3: The method according to aspect 1 or 2, wherein the indication is provided in the second downlink RACH message or the physical downlink control channel (PDCCH) of the second RACH message.

[0133] Aspect 4: The method according to any one of Aspects 1-3, wherein the SRS is sent according to one or more predefined configuration parameters.

[0134] Aspect 5: The method according to any one of Aspects 1-4, wherein the SRS is transmitted according to one or more configuration parameters indicated in the first downlink RACH message.

[0135] Aspect 6: The method according to any one of Aspects 1-5, wherein the SRS is transmitted according to one or more configuration parameters indicated in the Media Access Control (MAC) control element (CE) of the second downlink RACH message transmission.

[0136] Aspect 7: The method according to any one of Aspects 1-6, wherein the SRS is transmitted on the first set of resources based on the second set of resources used by the UE to send the second downlink RACH message.

[0137] Aspect 8: The method according to any one of Aspects 1-7, wherein SRS is sent on a set of resources based on one or more rules.

[0138] Aspect 9: The method according to any one of Aspects 1-8, wherein SRS is transmitted on a set of resources based on one or more parameters indicated in the ingress MAC CE of the second downlink RACH message.

[0139] Aspect 10: The method according to any one of Aspects 1-9, wherein an SRS is transmitted on a frequency resource indicated in a second downlink RACH message or the PDCCH of a second RACH message.

[0140] Aspect 11: The method according to aspect 10, wherein the frequency resources include at least one of SRS bandwidth or frequency allocation within SRS bandwidth.

[0141] Aspect 12: The method according to aspect 10 or 11, wherein the frequency resources are indicated in the MAC CE transmitted by the second downlink RACH message or in the bit field of the PDCCH of the second RACH message.

[0142] Aspect 13: A method for performing wireless communication by a network entity, comprising sending a first downlink RACH message to a UE, sending a second downlink RACH message to the UE after the first downlink RACH message, signaling to the UE an indication that the UE will send an SRS after the second downlink RACH message, and monitoring the SRS transmission from the UE after the second downlink RACH message according to the indication.

[0143] Aspect 14: The method according to aspect 13, wherein the indication is provided in the first downlink RACH message.

[0144] Aspect 15: The method according to aspect 13 or 14, wherein the indication is signaled in the second downlink RACH message or the PDCCH of the second RACH message.

[0145] Aspect 16: The method according to any one of Aspects 13-15, wherein the network entity monitors the SRS according to one or more predefined configuration parameters.

[0146] Aspect 17: The method according to any one of Aspects 13-16, wherein the network entity monitors the SRS according to one or more configuration parameters indicated in the first downlink RACH message.

[0147] Aspect 18: The method according to any one of Aspects 13-17, wherein the network entity monitors the SRS according to one or more configuration parameters indicated in the MAC CE delivered by the second downlink RACH message.

[0148] Aspect 19: The method according to any one of Aspects 13-18, wherein the network entity monitors SRS on the first set of resources based on the second set of resources used by the UE to send a second downlink RACH message.

[0149] Aspect 20: The method according to any one of Aspects 13-19, wherein a network entity monitors SRS on a set of resources based on one or more rules.

[0150] Aspect 21: The method according to any one of Aspects 13-20, wherein the network entity monitors the SRS on a set of resources based on one or more parameters indicated in the MAC CE of the second downlink RACH message.

[0151] Aspect 22: The method according to any one of Aspects 13-21, wherein the network entity monitors the SRS on a frequency resource indicated in a second downlink RACH message or the PDCCH of the second RACH message.

[0152] Aspect 23: The method according to aspect 22, wherein the frequency resources include at least one of SRS bandwidth or frequency allocation within SRS bandwidth.

[0153] Aspect 24: The method according to aspect 22 or 23, wherein the network entity indicates frequency resources in the MAC CE delivered by the second downlink RACH message, or in the bit field of the PDCCH of the second RACH message.

[0154] Aspect 25: An apparatus for conducting wireless communication, comprising a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to perform one or more operations of aspects 1-24.

[0155] Aspect 26: An apparatus for wireless communication, comprising components for performing one or more operations of aspects 1-24.

[0156] Aspect 27: A computer-readable medium having instructions stored thereon for performing one or more operations of aspects 1-24.

[0157] The techniques described in this article can be used in various wireless communication technologies, such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), LTE-Advanced (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. CDMA networks can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other CDMA variants. cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks can 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 the Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are UMTS versions using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called the 3rd Generation Partnership Project (3GPP). cdma2000 and UMB are described in documents from an organization called the 3rd Generation Partnership Project 2 (3GPP2). NR is an emerging wireless communication technology under development.

[0158] The techniques described herein can be used in the wireless networks and radio technologies mentioned above, as well as other wireless networks and radio technologies. For clarity, although terms commonly associated with 3G, 4G, and / or 5G wireless technologies may be used to describe aspects herein, aspects of this disclosure can be applied to other generation-based communication systems.

[0159] In 3GPP, depending on the context in which the term is used, the term "cell" can refer to the coverage area of ​​a Node B (NB) and / or the NB subsystem serving that coverage area. In NR systems, the term "cell" is used interchangeably with BS, Next Generation Node B (gNB or gNodeB), Access Point (AP), Distributed Unit (DU), Carrier, or Transmitter Receiver Point (TRP). A BS can provide communication coverage to macrocells, picocells, femtocells, and / or other types of cells. A macrocell can cover a relatively large geographic area (e.g., a radius of several kilometers) and can allow unrestricted access for UEs with service subscriptions. A picocell can cover a relatively small geographic area and can allow unrestricted access for UEs with service subscriptions. A femtocell can cover a relatively small geographic area (e.g., a home) and can allow restricted access for UEs associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in a home, etc.). A BS used for a macrocell can be called a macro BS. A BS for a picocell can be called a pico BS. A BS for a femtocell can be called a femto BS or a home BS.

[0160] A UE can also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smartphone, 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, biosensor / device, wearable device (such as smartwatch, smart clothing, smart glasses, smart bracelet), smart jewelry (e.g., smart ring, smart bracelet, etc.), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, GPS device, or any other suitable device configured to communicate via wireless or wired media. Some UEs can 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 the BS, another device (e.g., a remote device), or other entities. Wireless nodes can provide connectivity to networks (e.g., wide area networks such as the Internet or cellular networks) via wired or wireless communication links. Some UEs can be considered Internet of Things (IoT) devices; they can be narrowband IoT (NB-IoT) devices.

[0161] Some wireless networks (e.g., LTE) utilize Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and Single-Carrier Frequency Division Multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, often referred to as tones, bins, etc. Each subcarrier can be modulated with data. Modulation symbols are transmitted in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the subcarrier spacing could be 15 kHz, and the minimum resource allocation (called a "resource block" (RB)) could be 12 subcarriers (or 180 kHz). Therefore, for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, the nominal Fast Fourier Transform (FFT) size could be 128, 256, 512, 1024, or 2048, respectively. System bandwidth can also be divided into subbands. For example, a subband can cover 1.08MHz (i.e., 6 RBs), and there can be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10, or 20MHz, respectively. In LTE, the basic transmission time interval (TTI) or packet duration is a 1ms subframe.

[0162] NR can use OFDM with CP on both uplink and downlink and includes support for half-duplex operation using TDD. In NR, a subframe is still 1ms, but the basic TTI is called a slot. A subframe contains a variable number of slots (e.g., slots 1, 2, 4, 8, 16…) depending on the subcarrier spacing. NR RB is 12 consecutive frequency subcarriers. NR can support a basic subcarrier spacing of 15kHz, and other subcarrier spacings can be defined relative to the basic subcarrier spacing, such as 30kHz, 60kHz, 120kHz, 240kHz, etc. Symbol and slot lengths scale with the subcarrier spacing. CP length also depends on the subcarrier spacing. Beamforming can be supported and beam direction can be dynamically configured. MIMO transmission with pre-decoding can also be supported. In some examples, MIMO configuration in DL can support up to 8 transmit antennas, multi-layer DL transmission up to 8 streams, and up to 2 streams per UE. In some examples, multi-layer transmission with up to 2 streams per UE can be supported. It can support aggregation of multiple cells from up to 8 service cells.

[0163] In some examples, access to the air interface can be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication between some or all devices and equipment within its service area or cell. The scheduling entity can be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize the resources allocated by the scheduling entity. The base station is not the only entity that can act as a scheduling entity. In some examples, a UE can act as a scheduling entity and can schedule resources for one or more subordinate entities (e.g., one or more other UEs), and other UEs can use the resources scheduled by the UE for wireless communication. In some examples, a UE can act as a scheduling entity in a point-to-point (P2P) network and / or a mesh network. In the mesh network example, in addition to communicating with a scheduling entity, UEs can also communicate directly with each other.

[0164] In some examples, two or more dependent entities (e.g., UEs) can communicate with each other using sidelink signaling. Real-world applications of such sidelink communication might include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communication, Internet of Things (IoE) communication, IoT communication, mission-critical meshes, and / or various other suitable applications. Typically, sidelink signaling can refer to a signal transmitted from one dependent entity (e.g., UE1) to another dependent entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., a UE or BS), even if the scheduling entity may be used for scheduling and / or control purposes. In some examples, licensed spectrum can be used to transmit sidelink signals (unlike wireless LANs that typically use unlicensed spectrum).

[0165] The methods disclosed herein include one or more steps or actions for implementing the methods. The method steps and / or actions may be interchanged 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 a particular step and / or action may be modified without departing from the scope of the claims.

[0166] As used herein, the phrase “at least one of” in a list of items refers to any combination of those items, including a single member. 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 order of a, b, and c).

[0167] As used herein, the term "determine" encompasses a variety of actions. For example, "determine" can include operations, calculations, processing, derivation, investigation, searching (e.g., looking in a table, database, or other data structure), ascertaining, etc. Furthermore, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), etc. Additionally, "determine" can include parsing, selecting, picking, building, etc.

[0168] The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will readily be understood by those skilled in the art, and the universal principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be given the full scope consistent with the language of the claims, wherein, unless expressly stated otherwise, an element referred to in the singular is not intended to mean “one and only one,” but rather “one or more.” Unless expressly stated otherwise, the term “some” means one or more. All structural and functional equivalents of elements throughout the various aspects described in this disclosure that are known or will be known hereafter by those skilled in the art are expressly incorporated herein by reference and are intended to be covered by the claims. Moreover, regardless of whether the contents disclosed herein are expressly recited in the claims, they are not intended to be disclosed to the public. Pursuant to the provisions of 35 U.SC §112(f), no claim element is interpreted unless the element is expressly stated using the phrase “component for…” or, in the case of a method claim, the element is stated using the phrase “step for…”.

[0169] The various operations described above can be performed by any suitable component capable of performing the corresponding function. This component may include various hardware and / or one or more software components and / or one or more modules, including but not limited to circuits, application-specific integrated circuits (ASICs), or processors. Typically, where operations as shown in the figures are present, those operations may have corresponding components with similar numbering, plus functional components.

[0170] The various illustrative logic blocks, modules, and circuits disclosed herein can be implemented or executed using a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), 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. The general-purpose processor may be a microprocessor, but alternatively, 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, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors integrated with a DSP core, or any other such configuration.

[0171] If implemented in hardware, the example hardware configuration could include a processing system in a wireless node. This processing system could be implemented using a bus architecture. The bus can contain any number of interconnect buses and bridges, depending on the specific application and overall design constraints of the processing system. The bus can connect various circuits, including a processor, machine-readable media, and a bus interface. The bus interface can be used to connect network adapters, etc., to the processing system via the bus. The network adapter can be used to implement signal processing functions at the PHY layer. In user terminal 120 (see...) Figure 1 In this case, the user interface (e.g., keyboard, display, mouse, joystick, etc.) can also be connected to the bus. This bus can also link various other circuits well known in the art, such as timing sources, peripherals, voltage regulators, power management circuits, etc., and therefore will not be described further. The processor can be implemented using one or more general-purpose and / or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits capable of executing software. Those skilled in the art will recognize how the functions described for the processing system can be optimally implemented based on the specific application and the overall design constraints imposed on the system as a whole.

[0172] If implemented in software, the functions can be stored or transmitted as one or more instructions or codes on a computer-readable medium. 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 otherwise. Computer-readable media includes computer storage media and communication media, with communication media including any medium that facilitates the transfer of computer programs from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage medium. The computer-readable storage medium may be coupled to the processor, allowing the processor to read information from and write information to the storage medium. Alternatively, the storage medium may be integrated with the processor. For example, the machine-readable medium may include a transmit line, a carrier wave modulated by data, and / or a computer-readable storage medium on which instructions separate from the wireless node are stored, all accessible to the processor via a bus interface. Alternatively or additionally, the machine-readable medium or any portion thereof may be integrated into the processor, such as in cases where it may have a cache and / or a general-purpose register file. Examples of machine-readable storage media may include, for example, 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, disks, optical disks, hard disks, or any other suitable storage media, or any combination thereof. The machine-readable medium may be included in a computer program product.

[0173] A software module may include a single instruction or multiple instructions and may be distributed across several different code segments, different programs, and multiple storage media. The computer-readable medium may include multiple software modules. A software module includes instructions that, when executed by a device such as a processor, cause the processing system to perform various functions. The software module may include send and receive modules. Each software module may reside in a single storage device or be distributed across multiple storage devices. For example, when a trigger event occurs, a software module may be loaded from a hard disk drive into RAM. During the execution of a software module, the processor may load some instructions into a cache to improve access speed. One or more cache lines may then be loaded into a general-purpose register file for processor execution. When the functionality of a software module is mentioned below, it will be understood that this functionality is implemented by the processor when executing the instructions from that software module.

[0174] Furthermore, any connection is appropriately referred to as computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio, and microwave, the definition of medium includes coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave. The disks and optical discs used herein include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and... Optical discs, where magnetic disks typically copy data magnetically, copy data optically using lasers. Therefore, in some aspects, computer-readable media can include non-transitory computer-readable media (e.g., tangible media). Furthermore, in other aspects, computer-readable media can include transient computer-readable media (e.g., signals). Combinations of the above should also be included within the scope of computer-readable media.

[0175] Therefore, 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 instructions stored thereon (and / or encoded thereon) that can be executed by one or more processors to perform the operations described herein, for example, for performing the operations described herein and... Figure 7-8 The instructions for operation and technology are shown.

[0176] Furthermore, it should be understood that modules and / or other suitable components for performing the methods and techniques described herein may be downloaded and / or otherwise obtained by the user terminal and / or base station where applicable. For example, such a device may be coupled to a server to facilitate the transfer of components for performing the methods described herein. Alternatively, the various methods described herein may be provided by storage components (e.g., RAM, ROM, physical storage media such as CDs or floppy disks, etc.), allowing the user terminal and / or base station to obtain the various methods by coupling or providing the storage components to the device. Furthermore, any other suitable techniques for providing the methods and techniques described herein to the device may be utilized.

[0177] It should be understood that the claims are not limited to the precise configuration and components described above. Various modifications, alterations, and variations may be made to the arrangement, operation, and details of the described methods and apparatus without departing from the scope of the claims.

Claims

1. A method for wireless communication by a user equipment (UE), comprising: Receive the first downlink random access channel (RACH) message; The second downlink RACH message is received after the first downlink RACH message; Receive signaling instructing the UE to send a sounding reference signal (SRS) after the second downlink RACH message; as well as According to the instruction, the SRS is sent after the second downlink RACH message. Specifically, the SRS is transmitted on the first set of resources based on the second set of resources used by the UE to confirm the sending of the second downlink RACH message.

2. The method according to claim 1, wherein, The indication is provided in the first downlink RACH message.

3. The method according to claim 1, wherein, The indication is provided in the second downlink RACH message or in the physical downlink control channel (PDCCH) used for the second downlink RACH message.

4. The method according to claim 1, wherein, The SRS is sent according to one or more predefined configuration parameters.

5. The method according to claim 1, wherein, The SRS is sent according to one or more configuration parameters indicated in the first downlink RACH message.

6. The method according to claim 1, wherein, The SRS is sent according to one or more configuration parameters indicated in the Media Access Control (MAC) control element (CE) of the second downlink RACH message transmission.

7. A method for wireless communication by a network entity, comprising: Send a first downlink random access channel (RACH) message to the user equipment (UE); A second downlink RACH message is sent to the UE after the first downlink RACH message; The UE is signaled to indicate that it will send a sounding reference signal (SRS) after the second downlink RACH message; as well as According to the instruction, SRS transmission from the UE is monitored after the second downlink RACH message. Specifically, based on the second set of resources used by the UE to confirm the sending of the second downlink RACH message, the network entity monitors the SRS on the first set of resources.

8. The method according to claim 7, wherein, The indication is provided in the first downlink RACH message.

9. The method according to claim 7, wherein, The indication is communicated via signaling in the second downlink RACH message or in the physical downlink control channel (PDCCH) used for the second downlink RACH message.

10. The method according to claim 7, wherein, The network entity monitors the SRS according to one or more predefined configuration parameters.

11. The method according to claim 7, wherein, The network entity monitors the SRS based on one or more configuration parameters indicated in the first downlink RACH message.

12. The method according to claim 7, wherein, The network entity monitors the SRS according to one or more configuration parameters indicated in the Media Access Control (MAC) control element (CE) of the second downlink RACH message transmission.

13. An apparatus for wireless communication by a user equipment (UE), comprising a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: Receive the first downlink random access channel (RACH) message; The second downlink RACH message is received after the first downlink RACH message; Receive signaling instructing the UE to send a sounding reference signal (SRS) after the second downlink RACH message; and According to the instruction, the SRS is sent after the second downlink RACH message. in, The SRS is transmitted on the first set of resources based on the second set of resources used by the UE to confirm the transmission of the second downlink RACH message.

14. The apparatus according to claim 13, wherein, The indication is provided in the first downlink RACH message.

15. The apparatus according to claim 13, wherein, The indication is provided in the second downlink RACH message or in the physical downlink control channel (PDCCH) used for the second downlink RACH message.

16. An apparatus for wireless communication by a network entity, comprising a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: Send a first downlink random access channel (RACH) message to the user equipment (UE); A second downlink RACH message is sent to the UE after the first downlink RACH message; The UE is signaled to indicate that it will send a sounding reference signal (SRS) after the second downlink RACH message; as well as According to the instruction, SRS transmission from the UE is monitored after the second downlink RACH message. Specifically, based on the second set of resources used by the UE to confirm the sending of the second downlink RACH message, the network entity monitors the SRS on the first set of resources.

17. The apparatus according to claim 16, wherein, The indication is provided in the first downlink RACH message.

18. The apparatus according to claim 16, wherein, The indication is communicated via signaling in the second downlink RACH message or in the physical downlink control channel (PDCCH) used for the second downlink RACH message.

19. An apparatus for wireless communication by a user equipment (UE), comprising a component for performing the method according to any one of claims 1 to 6.

20. An apparatus for wireless communication by a network entity, comprising components for performing the method according to any one of claims 7 to 12.

21. A non-transitory computer-readable storage medium for wireless communication, wherein the instructions, when executed, cause a processor to perform the method according to any one of claims 1 to 6.

22. A non-transitory computer-readable storage medium for wireless communication, wherein the instructions, when executed, cause a processor to perform the method according to any one of claims 7 to 12.

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