Hybrid Automatic Repeat Request (HARQ) process when using the sidelink for retransmission

Abstract

Certain aspects of the present disclosure provide techniques for sidelink assisted retransmission, wherein a first UE obtains first data intended for a second UE by decoding a first transmission of first data for the second UE, receives signaling indicating that the first UE will retransmit the first data to the second UE, and in response to the signaling, retransmits the first data to the second UE via a sidelink.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application No. 16 / 943,098, filed on July 30, 2020, which application hereby claims priority under 35 U.S.C. 112 to pending U.S. Provisional Patent Application No. 62 / 927,814, filed on October 30, 2019, the entire contents of which are incorporated herein in their entirety. Technical Field

[0003] Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for using a sidelink to assist in retransmission of data. Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, etc. These wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, Advanced LTE (LTE-A) systems, Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, to name a few.

[0005] In some examples, a wireless multiple access communication system may include multiple base stations (BS), each of which is capable of simultaneously supporting communications for multiple communication devices (or referred to as user equipment (UE)). In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation, new radio (NR) or 5G network), a wireless multiple access communication system may include multiple distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) communicating with multiple central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), wherein a group of one or more DUs communicating with a CU may define an access node (e.g., which may be referred to as a BS, 5G NB, next generation NodeB (gNB or gNodeB), transmission reception point (TRP), etc.). A BS or DU may communicate with a set of UEs on a downlink channel (e.g., for transmission from a BS or DU to a UE) and an uplink channel (e.g., for transmission from a UE to a BS or DU).

[0006] These multiple access technologies are adopted in various telecommunication standards in order to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. NR (such as New Radio or 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR aims to better support mobile broadband Internet access by improving spectral efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards using OFDMA with cyclic prefix (CP) on downlink (DL) and uplink (UL). To this end, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0007] However, as the demand for mobile broadband access continues to grow, there is a need for further improvements to NR and LTE technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies. Summary of the invention

[0008] The systems, methods, and devices of the present disclosure each have several aspects, no single aspect being solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the appended claims, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description of the Invention," one will understand how the features of the present disclosure provide advantages including improved communications between access points and stations in a wireless network.

[0009] Certain aspects provide a method for wireless communication by a first user equipment (UE). The method generally includes obtaining first data for a second UE by decoding a first transmission of the first data for the second UE, receiving signaling indicating that the first UE is to retransmit the first data to the second UE, and in response to the signaling, retransmitting the first data to the second UE via a sidelink.

[0010] Certain aspects provide a method for wireless communication by a network entity. The method generally includes transmitting first data intended for a second UE in a first transmission, and if the network entity fails to receive an acknowledgment that the second UE successfully received the first data in the first transmission, signaling the first UE to retransmit the first data to the second UE via a sidelink.

[0011] Certain aspects provide a first UE. The first UE generally includes: a processing system configured to obtain first data for a second UE by decoding a first transmission of the first data for the second UE, a receiver configured to receive signaling indicating that the first UE will retransmit the first data to the second UE, and a transmitter configured to retransmit the first data to the second UE via a side link in response to the signaling.

[0012] Certain aspects provide a network entity. The network entity generally includes: a processing system configured to generate first data, and a transmitter configured to transmit the first data to a second UE in a first transmission, and if the network entity fails to receive an acknowledgment that the second UE successfully received the first data in the first transmission, signal the first UE to retransmit the first data to the second UE via a sidelink.

[0013] Certain aspects provide a first UE. The first UE generally includes means for obtaining first data for a second UE by decoding a first transmission of the first data for the second UE, means for receiving signaling indicating that the first UE will retransmit the first data to the second UE, and means for retransmitting the first data to the second UE via a sidelink in response to the signaling.

[0014] Certain aspects provide a network entity. The network entity generally includes means for transmitting first data intended for a second UE in a first transmission, and means for signaling the first UE to retransmit the first data to the second UE via a sidelink if the network entity fails to receive an acknowledgment that the second UE successfully received the first data in the first transmission.

[0015] Certain aspects provide an apparatus for wireless communication by a first UE. The apparatus generally includes: a processing system configured to obtain first data for a second UE by decoding a first transmission of the first data for the second UE, and obtain signaling indicating that the first UE will retransmit the first data to the second UE, and an interface configured to output the first data for retransmission to the second UE via a side link in response to the signaling.

[0016] Certain aspects provide an apparatus for wireless communication by a network entity. The apparatus generally includes an interface configured to output first data for transmission to a second UE, and a processing system further configured to signal the first UE to retransmit the first data to the second UE via a sidelink if the network entity fails to receive an acknowledgment that the second UE successfully received the first data in the first transmission.

[0017] Certain aspects provide a computer-readable medium for wireless communication by a first UE. The computer-readable medium generally includes code that can be executed to obtain first data for a second UE by decoding a first transmission of the first data for the second UE, receive signaling indicating that the first UE will retransmit the first data to the second UE, and in response to the signaling, retransmit the first data to the second UE via a sidelink.

[0018] Certain aspects provide a computer-readable medium for wireless communication by a network entity. The computer-readable medium generally includes code executable to transmit first data intended for a second UE in a first transmission, and to signal the first UE to retransmit the first data to the second UE via a sidelink if the network entity fails to receive an acknowledgment that the second UE successfully received the first data in the first transmission.

[0019] Certain aspects provide components, means, and / or computer-readable media having computer-executable code stored thereon for performing the techniques described herein.

[0020] To achieve the foregoing and related ends, one or more aspects include features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are only indicative of a few of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to be able to understand in detail the manner in which the above features of the present disclosure are achieved, the above brief overview may be described in more detail by reference to various aspects (some of which are illustrated in the accompanying drawings). However, it should be noted that the accompanying drawings only illustrate certain typical aspects of the present disclosure and therefore should not be considered as limiting the scope thereof, as the description may allow for other equally effective aspects.

[0022] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0023] Figure 2 is a block diagram conceptually illustrating designs of example base stations (BSs) and user equipment (UEs) in accordance with certain aspects of the present disclosure.

[0024] Figure 3 An example of a frame format for a New Radio (NR) system is shown, in accordance with certain aspects of the present disclosure.

[0025] Figure 4A and Figure 4B An example sidelink communication mode is shown in which certain aspects of the present disclosure may be practiced.

[0026] Figure 5 Example operations that may be performed by a UE in accordance with certain aspects of the present disclosure are illustrated.

[0027] Figure 6 Example operations that may be performed by a network entity in accordance with certain aspects of the present disclosure are illustrated.

[0028] Fig. 7A and Figure 7B Examples of sidelink assisted retransmissions in accordance with certain aspects of the present disclosure are shown.

[0029] Figure 8A-8C Example steps for implementing sidelink assisted retransmission in accordance with certain aspects of the present disclosure are shown.

[0030] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation. DETAILED DESCRIPTION

[0031] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for using a sidelink to assist in retransmission of data (sidelink-assisted retransmission).

[0032] The following description provides examples, rather than limitations on the scope, applicability, or examples set forth in the claims. Without departing from the scope of the present disclosure, the functions and arrangements of the elements discussed may be changed. Various examples may appropriately omit, replace, or add various programs or components. For example, the method may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, the features described for some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or implement a method. In addition, the scope of the present disclosure is intended to cover such a device or method, which is practiced using other structures, functions, or structures and functions other than or different from the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of the claims. The word "exemplary" is used herein to mean "used as an example, instance, or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred or superior to other aspects.

[0033] The technology described herein can be used for 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. A CDMA network can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes bandwidth CDMA (WCDMA) and other CDMA variants. Cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network can implement radio technologies such as Global System for Mobile Communications (GSM). An OFDMA network can implement radio technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS).

[0034] New Radio (NR) is an emerging wireless communication technology being developed with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and Advanced LTE (LTE-A) are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents from an organization called "3rd Generation Partnership Project 2" (3GPP2). The technology described herein can be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, although terms commonly associated with 3G and / or 4G wireless technologies may be used herein to describe various aspects, various aspects of the present disclosure may be applied to other communication systems based on generations, such as 5G and later technologies, including NR technologies.

[0035] New Radio (NR) access (e.g., 5G technology) can support various wireless communication services, such as enhanced mobile broadband (eMBB) for wide bandwidth (e.g., 80 MHz or higher), millimeter wave (mmW) for high carrier frequency (e.g., 25 GHz or higher), massive machine type communication MTC (mMTC) for non-backward compatible MTC technology, and / or mission critical ultra-reliable low latency communication (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet their respective quality of service (QoS) requirements. In addition, these services may coexist in the same subframe.

[0036] Example Wireless Communication System

[0037] Figure 1 An example wireless communication network 100 is shown in which aspects of the present disclosure may be performed. For example, Figure 1 The UE 120 may be configured to perform the following reference Figure 6 The operation of the sidelink assisted retransmission described above. Similarly, Figure 1 The BS 110 may be configured to perform the operations described below with reference to FIG. 7 (eg, triggering the UE to perform operation 600 to assist in sidelink retransmission).

[0038] The wireless communication network 100 may be, for example, a new radio (NR) or 5G network. According to the operations described below with reference to FIGS. 8 , 12 , and 13 , the BS 110 may participate in a multi-transmission reception point (multi-TRP) transmission to the UE 120 .

[0039] 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 that communicates with a user equipment (UE). Each BS 110 may provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to the coverage area of ​​a Node B (NB) and / or a NB subsystem serving the coverage area, depending on the context in which the term is used. In the NR system, the term "cell" and the next generation NodeB (gNB or gNodeB), NRBS, 5G NB, access point (AP), or transmission reception point (TRP) may be used interchangeably. In some examples, the cell may not necessarily be fixed, and the geographical area of ​​the cell may move according to the location of the mobile BS. In some examples, the base station may be interconnected to each other and / or to one or more other base stations or network nodes (not shown) in the wireless communication network 100 through various types of backhaul interfaces (such as direct physical connections, wireless connections, virtual networks, or analogs using any suitable delivery network).

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

[0041] A BS may provide communication coverage for macro cells, pico cells, femto cells, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access to UEs with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access to UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access to UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in a home, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In Figure 1 In the illustrated example, BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more (e.g., three) cells.

[0042] The wireless communication network 100 may also include a relay station. A relay station is a station that receives transmissions of data and / or other information from an upstream station (e.g., a BS or UE) and transmits transmissions of data and / or other information to a downstream station (e.g., a UE or BS). A relay station may also be a UE that relays transmissions for other UEs. Figure 1 In the illustrated example, a relay station 110r may communicate with a BS 110a and a UE 120r to facilitate communication between the BS 110a and the UE 120r. A relay station may also be referred to as a relay BS, a relay, or the like.

[0043] The wireless communication network 100 may be a heterogeneous network including different types of BSs, such as a macro BS, a pico BS, a femto BS, a repeater, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different effects on interference in the wireless communication network 100. For example, a macro BS may have a high transmit power level (e.g., 20 watts), while a pico BS, a femto BS, and a repeater may have a lower transmit power level (e.g., 1 watt).

[0044] The wireless communication network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned over time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned over time. The techniques described herein may be used for both synchronous and asynchronous operation.

[0045] A network controller 130 may be coupled to a set of BSs and may provide coordination and control for these BSs. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with each other via a wireless or wired backhaul (eg, directly or indirectly).

[0046] UE 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE may be fixed or mobile. UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smart phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet computer, camera, gaming device, netbook, smartbook, ultrabook, appliance, medical device or medical equipment, biosensor / device, wearable device (such as smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, global positioning system device, or any other suitable device configured to communicate via wireless or wired medium. Some UEs may be considered as 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. that can communicate with a BS, another device (e.g., a remote device), or some other entity. For example, a wireless node can provide connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices, which can be narrowband IoT (NB-IoT) devices.

[0047] 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, which are also commonly referred to as tones, bins, etc. Each subcarrier can be modulated with data. Typically, modulation symbols are transmitted in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can be dependent on the system bandwidth. For example, the spacing of the subcarriers can be 15kHz, and the minimum resource allocation (called a "resource block" (RB)) can be 12 subcarriers (or 180kHz). Therefore, for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), the nominal fast Fourier transform (FFT) size can be equal to 128, 256, 512, 1024, or 2048, respectively. The system bandwidth may also be divided into subbands. For example, a subband may cover 1.08 MHz (ie, 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, respectively.

[0048] Although aspects of the examples described herein may be associated with LTE technology, aspects of the present disclosure may be applicable to other wireless communication systems, such as NR. NR may use OFDM with CP on the uplink and downlink and include support for half-duplex operation using TDD. Beamforming may be supported and the beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas, multi-layer DL transmissions of up to 8 streams, and up to 2 streams per UE. Multi-layer transmissions of up to 2 streams per UE may be supported. Aggregation of multiple cells of up to 8 serving cells may be supported.

[0049] In some examples, access to the air interface can be scheduled. A scheduling entity (e.g., BS) allocates resources for communications between some or all devices and equipment within its service area or cell. A scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, subordinate entities utilize resources allocated by the scheduling entity. The base station is not the only entity that can act as a scheduling entity. In a certain example, a UE may act as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and other UEs may use the resources scheduled by the UE for wireless communications. In some examples, a UE may act as a scheduling entity in a peer-to-peer (P2P) network and / or a mesh network. In a mesh network example, in addition to communicating with a scheduling entity, UEs may also communicate directly with each other.

[0050] exist Figure 1 In FIG. 1 , a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and / or uplink. A thin dashed line with double arrows indicates interfering transmissions between the UE and the BS.

[0051] Figure 2 BS 110 and UE 120 (eg, Figure 1 For example, antenna 252, processors 266, 258, 264, and / or controller / processor 280 of UE 120 may be configured to perform Figure 6 Operation 600 of FIG. 7 , and / or antenna 234 of BS 110 , processors 220 , 230 , 238 , and / or controller / processor 240 of BS 110 may be configured to perform operation 700 of FIG. 7 .

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

[0053] At the UE 120, antennas 252a to 252r may receive downlink signals from the base station 110 and may provide received signals to demodulators (DEMODs) in transceivers 254a to 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all demodulators 254a to 254r, perform MIMO detection on the received symbols (if applicable), and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 260, and provide decoded control information to a controller / processor 280.

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

[0055] Controllers / processors 220 and 280 may direct the operation at BS 110 and UE 120, respectively. Processor 220 and / or other processors and modules at BS 110 may perform or direct the execution of processes for the techniques described herein. Memories 242 and 282 may store data and program codes for BS 110 and UE 120, respectively. Scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0056] Figure 3 300 for NR. The transmission timeline for each of the downlink and uplink may be divided into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be divided into 10 subframes with indices 0 to 9, each subframe being 1 ms. Depending on the subcarrier spacing, each subframe may include a variable number of slots. Depending on the subcarrier spacing, each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols). The symbol periods in each slot may be assigned indices. A mini slot, which may be referred to as a subslot structure, may refer to a transmission time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols).

[0057] Each symbol within a slot may indicate a link direction (e.g., DL, UL, or flexible link direction) for data transmission, and the link direction of each subframe may be switched dynamically. The link direction may be based on the slot format. Each slot may include DL / UL data and DL / UL control information.

[0058] In NR, a synchronization signal (SS) block is transmitted. The SS block includes PSS, SSS, and dual-symbol PBCH. The SS block can be transmitted in a fixed time slot position, such as Figure 3 Symbols 0-3 shown in . The UE can use PSS and SSS for cell search and acquisition. PSS can provide half-frame timing, and SS can provide CP length and frame timing. PSS and SSS can provide cell identification. PBCH carries some basic system information, such as downlink system bandwidth, timing information within a radio frame, SS burst set periodicity, system frame number, etc. SS blocks can be organized into SS bursts to support beam scanning. Other system information such as remaining minimum system information (RMSI), system information block (SIB), other system information (OSI) can be sent on the physical downlink shared channel (PDSCH) in certain subframes. SS blocks can be sent 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 sent in the same frequency domain, while SS blocks in different SS burst sets can be sent at different frequency locations.

[0059] In some cases, two or more slave entities (e.g., UEs) may communicate with each other using sidelink signals. Practical applications of such sidelink communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical grids, and / or various other suitable applications. Generally, a sidelink signal may refer to a signal transmitted from one slave entity (e.g., UE1) to another slave entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., UE or BS), even though the scheduling entity may be used for scheduling and / or control purposes. In some instances, licensed spectrum (unlike wireless local area networks that typically use unlicensed spectrum) may be used to communicate sidelink signals.

[0060] The UE may operate in various radio resource configurations, including a configuration associated with sending a pilot using a dedicated resource set (e.g., a radio resource control (RRC) dedicated state, etc.), or a configuration associated with sending a pilot using a common resource set (e.g., an RRC common state, etc.). When operating in the RRC dedicated state, the UE may select a dedicated resource set for sending a pilot signal to the network. When operating in the RRC common state, the UE may select a common resource set for sending a pilot signal to the network. In either case, the pilot signal sent by the UE may be received by one or more network access devices (such as one or a DU, or a portion of the network access devices thereof). Each receiving network access device may be configured to receive and measure pilot signals sent on a common resource set, and also receive and measure pilot signals sent on a dedicated resource set allocated to a UE for which the network access device is a member of a network access device monitoring set for the UE. One or more of the receiving network access devices, or (one or more) CUs to which the receiving network access device sends the measurement of the pilot signal, may use these measurements to identify a serving cell for the UE, or to initiate a change of a serving cell for one or more of the UEs.

[0061] Example HARQ process when retransmission is performed using the sidelink

[0062] The NR network can provide sidelink transmission between a transmitter user equipment (UE) and a receiver UE. In some cases, the UE can be configured with multiple transmit resource pools and multiple receive resource pools. When data is to be transmitted using a resource pool, the actual transmission resource can be dynamically selected from the pool using one of various modes.

[0063] Within a PSCCH period, there are separate subframe pools and resource block pools for control (Physical Sidelink Control Channel or PSCCH) and data (Physical Sidelink Shared Channel or PSSCH). Typically, a PSCCH subframe precedes a subframe for PSSCH transmissions, similar to how in the traditional way (direct link), the control region precedes the data portion of the subframe. The PSCCH carries a Sidelink Control Information (SCI) message that describes the dynamic transmission properties of the PSSCH that follows it. The receiving UE searches for the SCI transmissions it is interested in among all configured PSCCH resource pools. A UE can be a member of more than one sidelink communication group.

[0064] Various use cases for sidelink communications include the Industrial Internet of Things (IoT), where, for example, UEs can communicate measurement and control data. Features of sidelink communications that may benefit Industrial IoT applications include reduced latency, multipath diversity, extended coverage, extended battery life, location enhancement, and infrastructure-free communications.

[0065] Figure 4AThe diagram illustrates a first scenario applicable to IoT, in which a serving base station (e.g., gNB) can allocate resources for sidelink communications. Figure 4A The example assumes that the gNB has allocated sidelink resources, at least for transmission from the transmitter UE (S2) to the receiver UE (S1). In another mode, the transmitting UE itself can select the resources according to some rules (e.g., designed to reduce collisions). Figure 4B A second scenario is illustrated, where another device such as a PLC (Programmable Logic Controller) communicates with the UE. In such a scenario, the control signal may come from a gNB (e.g. Figure 4A ) or from a PLC.

[0066] exist Figure 4A and 4B In the scenario shown, the initial transmission to the UE (e.g., control signal) occurs via a direct link from the gNB ( Figure 4A ), or can occur via a direct link from the PLC or gNB ( Figure 4B ). However, in some cases these initial transmissions may not be successful, for example, due to congestion or poor channel conditions.

[0067] In this case, various aspects of the present disclosure propose using sidelink communications between UEs to assist in retransmissions. As will be described in more detail below, in the event that the initial transmission from the gNB or sidelink is unsuccessful, a UE or group of UEs can be recruited to retransmit data.

[0068] Figure 5 Example operations 500 for wireless communications by a user equipment (UE) according to some aspects of the present disclosure are shown. Operations 500 may be performed, for example, by a first UE (e.g., UE 120 in wireless communication network 100) that assists a gNB or PLC in retransmitting to another UE via a sidelink.

[0069] At 502, operations 500 begin by decoding a first transmission of first data for a second UE to obtain first data intended for the second UE. At 504, the first UE receives signaling indicating that the first UE will retransmit the first data to the second UE. At 506, the first UE retransmits the first data to the second UE via a sidelink in response to the signaling.

[0070] Figure 6 Example operations 600 for wireless communications by a network entity are illustrated in accordance with some aspects of the present disclosure. Operations 600 may be performed, for example, by Figure 4A or 4B gNB or PLC to execute Figure 5 The operations 500 retransmit data via a side link with the assistance of the first UE.

[0071] Operations 600 begin at 602 by transmitting first data intended for a second UE in a first transmission. At 604, if the network entity fails to receive an acknowledgement that the second UE successfully received the first data in the first transmission, the network entity signals the first UE to retransmit the first data to the second UE via a sidelink.

[0072] Fig. 7A Shown for Figure 4A Figure 2 shows an example of sidelink assisted retransmission for the scenario shown in Figure 2. As shown, the initial (direct link) data transmission from the gNB to UE S1 may fail. Upon detecting the failure, e.g., after not receiving a positive acknowledgement (ACK) from UE S1, the gNB triggers UE S2 to retransmit the data to UE S1 via the sidelink. Figure 7B Shows Figure 4B A similar example of the scenario shown in FIG. 1 . As shown in the figure, after the PLC detects the failure of the initial transmission to UE S1 , the PLC triggers UE S2 to retransmit the data to UE S1 via the side link.

[0073] Various steps may be performed to prepare a UE or a group of UEs to assist with sidelink retransmissions. Figure 8A-8C An example of these steps is shown, and how the UE can then assist in retransmissions, for Figure 4A and 7A The scene shown. Figure 4B and 7B In the scenario shown, similar steps can be performed, for example, the PLC executes Figure 8A-8C Actions performed by the gNB in ​​the QoS policy (e.g., transmitting initial data and triggering retransmissions).

[0074] like Fig. 8A As illustrated in FIG, as an initial step (step 1), the UE may perform sidelink channel measurements (e.g., measuring sidelink RSRP using a pilot signal) and report the sidelink channel quality to the gNB. Based on the reported sidelink channel measurements, the gNB may determine a group of UEs for the sidelink (step 2). For example, a set of UEs that report good sidelink channel quality between each other may be grouped together, as sidelink retransmissions between these UEs may have the best chance of success.

[0075] In some cases, a UE that is a candidate for assisting retransmission of data via the sidelink may first acquire the data by monitoring the initial (direct link) transmission from the gNB. The gNB may confirm good candidates for assisted retransmission based on the acknowledgment feedback.

[0076] This is Figure 8B, where the gNB transmits an initial transmission for UE S1 (step 3). In this example, UE S1 fails to successfully receive the initial transmission (as indicated by an "X"). On the other hand, UE S2 successfully decodes the initial transmission and transmits an ACK to the gNB (effectively identifying itself as a potential assisting UE in step 4).

[0077] like Figure 8C As shown, after receiving an ACK from UE S2 (and not receiving an ACK from UE S1), the gNB transmits a trigger to UE S2 (at step 5). Upon receiving the trigger, UE S2 retransmits the data to UE S1 via the sidelink (step 6). The trigger signaling may take any suitable form, such as downlink control information (DCI). In some cases, the trigger may be sent to each UE in the group containing the initial transmission target. In this case, a separate UE-specific trigger may be sent or a groupcast trigger may be sent.

[0078] In some cases, the assisting UE (e.g., UE S2 in the above example) may also have its own data (e.g., transport blocks) to acknowledge. In this case, the assisting UE may transmit its own separate (separately encoded) ACK / NACK for its own TB. Alternatively, the assisting UE may transmit a single message with ACK jointly encoded with the TB for the target UE (e.g., UE S1 in the above example) and its own TB.

[0079] In some cases, the same or separate HARQ processes may be used for initial transmissions and retransmissions. For example, the initial transmission from the gNB / PLC may include the HARQ process ID in the DCI (if via a direct link from the gNB) or the SCI (if via a sidelink from the PLC). In some cases, retransmissions from assisting UEs may include the same HARQ process ID in the SCI corresponding to the retransmitted TB.

[0080] In some cases, the secondary UE may have sidelink traffic for the target UE in addition to the retransmitted data from the gNB / PLC to the target UE. In this case, the secondary UE may use a mechanism to distinguish between the two HARQ processes.

[0081] According to one option, the UE can add a bit in the SCI to indicate whether the HARQ process is used to assist the UE's own sidelink traffic or for the retransmitted traffic of the gNB / PLC. According to another option, a subset of HARQ IDs can be reserved for retransmitted traffic. In other words, these HARQ IDs can be used only for retransmitted traffic.

[0082] The method disclosed herein includes one or more steps or actions for implementing the method. Without departing from the scope of the claims, the method steps and / or actions can be interchangeable with each other. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of the claims.

[0083] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc or any other order of a, b, and c).

[0084] As used herein, the term "determine" includes a variety of actions. For example, "determine" may include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, a database, or another data structure), ascertaining, etc. In addition, "determine" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. In addition, "determine" may include resolving, selecting, choosing, establishing, etc.

[0085] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the various aspects shown herein, but should be given a full scope consistent with the language of the claims, wherein, unless explicitly stated, the elements mentioned in the singular are not intended to mean "one and only one", but "one or more". Unless otherwise explicitly stated, the term "some" refers to one or more. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure, which are known or will be known to those of ordinary skill in the art, are expressly incorporated herein by reference and are intended to be covered by the claims. Moreover, regardless of whether the content disclosed herein is explicitly stated in the claims, it is not intended to be disclosed to the public. According to the provisions of 35 U.S.C. § 112 (f), unless the element is explicitly stated using the phrase "parts for...", or in the case of a method claim, the element is stated using the phrase "step for...".

[0086] The various operations of the methods described above may be performed by any suitable component capable of performing the corresponding functions. The 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. Generally, where there are operations shown in the figure, these operations may have corresponding counterpart means-plus-function components with similar numbers. For example, Figure 5 The various operations shown in Figure 2 The various processors shown in (such as processors 266, 258, 264 and / or controller / processor 280 of UE 120) are executed. Figure 6 The various operations shown in Figure 2 10 and 110. The various processors shown in FIG. 10 (such as processors 220, 230, 238 and / or controller / processor 240 of BS 110) may be used to execute.

[0087] The components for receiving may include Figure 2 The receiver (such as one or more antennas or a receiving processor) shown in FIG. The means for sending, the means for retransmitting and / or the means for transmitting may include Figure 2 The transmitter (such as one or more antennas or a transmit processor) illustrated in FIG. The means for measuring, the means for reporting, the means for providing, the means for distinguishing, the means for selecting, and the means for including may include a processing system, which may include one or more processors, such as processors 266, 258, 264 and / or controller / processor 280 of UE 120 and / or Figure 2 1. The processors 220, 230, 238 and / or controller / processor 240 of BS 110 are shown in FIG.

[0088] In some cases, a device may have an interface (a component for outputting) to output a frame for transmission, rather than actually sending a frame. For example, a processor may output a frame to a radio frequency (RF) front end via a bus interface for transmission. Similarly, a device may have an interface (a component for obtaining) to obtain a frame received from another device, rather than actually receiving a frame. For example, a processor may obtain (or receive) a frame from an RF front end for reception via a bus interface.

[0089] The various illustrative logic blocks, modules, and circuits described in conjunction with the present disclosure may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general purpose processor may be a microprocessor, but as an alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0090] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus may link together various circuits including a processor, a machine-readable medium, and a bus interface. Among other things, the bus interface may be used to connect a network adapter to the processing system via the bus. The network adapter may be used to implement signal processing functions at the PHY layer. In the user terminal 120 (see Figure 1 ), a user interface (e.g., keyboard, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, etc., which are well known in the art and therefore will not be described further. The processor may be implemented using one or more general and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits that can execute software. Those skilled in the art will recognize how to best implement the functionality described for the processing system depending on the specific application and the overall design constraints imposed on the entire system.

[0091] If implemented in software, the function may be stored on or sent via a computer-readable medium as one or more instructions or codes. Whether referred to as software, firmware, middleware, microcode, hardware description language or otherwise, software should be broadly interpreted as meaning instructions, data or any combination thereof. Computer-readable media include both computer storage media and communication media, and communication media include any media that facilitates the delivery of a computer program 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 a machine-readable storage medium. A computer-readable storage medium may be coupled to a processor so that the processor may read information from the storage medium and write information to the storage medium. Alternatively, a storage medium may be integrated into a processor. For example, the machine-readable medium may include a transmission line, a carrier modulated by data, and / or a computer-readable storage medium on which instructions separated from a wireless node are stored, all of which may be accessed by a processor via a bus interface. Alternatively or additionally, the machine-readable medium or any portion thereof may be integrated into a processor, such as a cache and / or a general register file. By way of example, 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, magnetic disks, optical disks, hard drives, or any other suitable storage media, or any combination thereof. The machine-readable medium may be included in a computer program product.

[0092] A software module may include a single instruction or multiple instructions, and may be distributed over several different code segments, between different programs, and across 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 a processing system to perform various functions. The software module may include a sending module and a receiving module. Each software module may reside in a single storage device, or may be distributed across multiple storage devices. By way of example, when a triggering event occurs, a software module may be loaded from a hard drive into a RAM. During the execution of a software module, a processor may load some instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When the functions of a software module are mentioned below, it will be understood that such functions are implemented by a processor when executing instructions from the software module.

[0093] Moreover, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared (IR), radio and microwave), then the definition of medium includes the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology such as infrared (IR), radio and microwave. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Optical disks, where magnetic disks typically reproduce data magnetically, and optical disks reproduce data optically via lasers. Thus, in some aspects, computer readable media may include non-transitory computer readable media (e.g., tangible media). Additionally, for other aspects, computer readable media may include transitory computer readable media (e.g., signals). Combinations of the above should also be included within the scope of computer readable media.

[0094] Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and / or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For example, a computer program product for performing the operations described herein and Figure 5 and / or Figure 6 The operations shown in the instructions.

[0095] In addition, it should be understood that the modules and / or other suitable components for performing the methods and techniques described herein can be downloaded and / or otherwise obtained by a user terminal and / or base station when applicable. For example, such a device can be coupled to a server to facilitate the delivery of components for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage component (e.g., RAM, ROM, a physical storage medium such as a compact disk (CD) or a floppy disk, etc.), so that the user terminal and / or base station can obtain the various methods when the storage component is coupled or provided to the device. In addition, any other suitable technology for providing the methods and techniques described herein to the device can be utilized.

[0096] It is to be understood that the claims are not limited to the precise configuration and components described above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method for wireless communication by a first user equipment UE, comprising: obtaining, from a network entity, first data intended for a second UE, wherein the obtaining comprises decoding a first transmission of the first data intended for the second UE; receiving signaling indicating that the first UE will retransmit the first data to the second UE; and In response to the signaling: sending sidelink control information SCI, the SCI scheduling a physical sidelink shared channel PSSCH transmission from the first UE to the second UE, wherein the SCI comprises a hybrid automatic repeat request HARQ process indicator ID, and wherein the SCI indicates that the HARQ process ID is associated with a retransmission of data from the network entity; and The first data is retransmitted to the second UE via the PSSCH.

2. The method according to claim 1, further comprising: measuring a channel quality of a side link between the first UE and the second UE; and The measured channel quality is reported to the network entity.

3. The method according to claim 1, further comprising: Signaling is received indicating that the first UE is part of a group of one or more UEs that retransmit data to the second UE.

4. The method according to claim 1, further comprising: obtaining, from the network entity, second data intended for the second UE, wherein the obtaining comprises decoding a second transmission of the second data intended for the second UE; and A first confirmation feedback is provided for the second transmission.

5. The method according to claim 4, further comprising: obtaining, from the network entity, third data intended for the first UE, wherein the obtaining comprises decoding a third transmission of third data for the first UE; and A second confirmation feedback is provided for the third transmission.

6. The method according to claim 5, wherein: The first acknowledgment feedback for the second transmission and the second acknowledgment feedback for the third transmission are jointly encoded.

7. The method according to claim 1, wherein: The first transmission includes a corresponding HARQ process ID.

8. The method according to claim 1, further comprising: sending a second SCI that schedules a second PSSCH transmission from the first UE to the second UE, wherein the second SCI includes a second HARQ process ID, and wherein the second SCI indicates that the second HARQ process ID is associated with sidelink data; and The sidelink data is sent to the second UE.

9. The method according to claim 1, wherein: A bit in the SCI indicates whether the HARQ process ID is associated with a retransmission of data from the network entity or with sidelink data.

10. The method according to claim 1, wherein: Also includes: A value for the HARQ process ID is selected from a first subset of HARQ process IDs, wherein the first subset of HARQ process IDs is reserved for retransmission of data intended for the first UE from the network entity by the first UE, and wherein a second subset of the HARQ process IDs is reserved for transmission of sidelink data from the first UE to the second UE.

11. A method for wireless communication by a network entity, comprising: outputting, in a first transmission, first data intended for a second UE; outputting, in a second transmission, second data intended for the first UE; obtaining, from the first UE, first acknowledgment feedback for the first transmission and second acknowledgment feedback for the second transmission, wherein the first acknowledgment feedback and the second acknowledgment feedback are jointly encoded; and When the network entity fails to receive the first confirmation feedback indicating that the second UE successfully received the first data in the first transmission, signaling the first UE to retransmit the first data to the second UE via a sidelink.

12. The method according to claim 11, further comprising: receiving, from the first UE, a report of a measured channel quality of the sidelink; including the first UE in a group of one or more UEs that retransmit data to the second UE; as well as The first UE is signaled to indicate that the first UE is part of the group.

13. A first user equipment UE, comprising: A processing system configured to: obtaining, from a network entity, first data intended for a second UE, wherein the processing system is configured to decode a first transmission of the first data intended for the second UE; a receiver configured to receive signaling indicating that the first UE will retransmit the first data to the second UE; as well as A transmitter, configured to respond to the signaling: Sending sidelink control information SCI, the SCI scheduling a physical sidelink shared channel PSSCH transmission from the first UE to the second UE, wherein the SCI includes a hybrid automatic repeat request HARQ process identifier ID, and wherein the SCI indicates that the HARQ process ID is associated with a retransmission of data from the network entity; and The first data is retransmitted to the second UE via the PSSCH.

14. The first UE according to claim 13, wherein: The processing system is also configured to: measuring a channel quality of a side link between the first UE and the second UE; and The measured channel quality is reported to the network entity.

15. The first UE according to claim 13, wherein the receiver is further configured to: Signaling is received indicating that the first UE is part of a group of one or more UEs that retransmit the data to the second UE.

16. The first UE according to claim 13, wherein: The processing system is also configured to: obtaining, from the network entity, second data intended for the second UE, wherein the processing system being configured to obtain the second data comprises the processing system being configured to decode a second transmission of the second data intended for the second UE; and A first confirmation feedback is provided for the second transmission.

17. The first UE according to claim 16, wherein: The processing system is further configured to obtain, from the network entity, third data intended for the first UE, wherein the processing system being configured to obtain the third data comprises the processing system being configured to decode a third transmission of the third data for the first UE; and The processing system is further configured to provide second acknowledgment feedback for the third transmission.

18. The first UE according to claim 17, wherein: The first acknowledgment feedback for the second transmission and the second acknowledgment feedback for the third transmission are jointly encoded.

19. The first UE according to claim 13, wherein: The first transmission includes the HARQ process ID.

20. The first UE according to claim 13, wherein: The transmitter is further configured to: transmit a second SCI, the second SCI scheduling a second PSSCH transmission from the first UE to the second UE, wherein the second SCI includes a second HARQ process ID, and wherein the second SCI indicates that the second HARQ process ID is associated with sidelink data; and The sidelink data is sent to the second UE.

21. The first UE according to claim 13, wherein: A bit in the SCI indicates whether the HARQ process ID is associated with a retransmission of data from the network entity or with sidelink data.

22. The first UE according to claim 13, wherein: The processing system is also configured to: A value for the HARQ process ID is selected from a first subset of HARQ process IDs, wherein the first subset of HARQ process IDs is reserved for retransmission of data intended for the first UE from the network entity by the first UE, and wherein a second subset of the HARQ process IDs is reserved for transmission of sidelink data from the first UE to the second UE.

23. A network entity, comprising: a processing system configured to generate first data intended for a second UE and second data intended for the first UE; as well as The transmitter is configured as: transmitting, in a first transmission, first data intended for the second UE; and transmitting, in a second transmission, second data intended for the first UE; and The receiver is configured as: receiving, from the first UE, first acknowledgment feedback for the first transmission and second acknowledgment feedback for the second transmission, wherein the first acknowledgment feedback and the second acknowledgment feedback are jointly encoded; and wherein The transmitter is configured to signal the first UE to retransmit the first data to the second UE via a sidelink when the network entity fails to receive the first confirmation feedback indicating that the second UE successfully received the first data in the first transmission.

24. The network entity according to claim 23, wherein: The receiver is configured to receive a measured channel quality report of the sidelink from the first UE; The processing system is further configured to include the first UE in a group of one or more UEs that retransmit data to the second UE; and The transmitter is further configured to signal the first UE that the first UE is part of the group.

25. A non-transitory computer-readable medium storing a program code, which, when executed by a processor, performs a method of wireless communication performed by a first user equipment UE, comprising: obtaining, from a network entity, first data intended for a second UE, wherein the obtaining comprises decoding a first transmission of the first data intended for the second UE; receiving signaling indicating that the first UE will retransmit the first data to the second UE; In response to the signaling: sending sidelink control information SCI, the SCI scheduling a physical sidelink shared channel PSSCH transmission from the first UE to the second UE, wherein the SCI comprises a hybrid automatic repeat request HARQ process indicator ID, and wherein the SCI indicates that the HARQ process ID is associated with a retransmission of data from the network entity; and The first data is retransmitted to the second UE via the PSSCH.

26. A non-transitory computer readable medium storing program code, which, when executed by a processor, performs a method of wireless communication performed by a network entity, comprising: outputting, in a first transmission, first data intended for a second UE; outputting, in a second transmission, second data intended for the first UE; obtaining, from the first UE, first acknowledgment feedback for the first transmission and second acknowledgment feedback for the second transmission, wherein the first acknowledgment feedback and the second acknowledgment feedback are jointly encoded; and When the network entity fails to receive the first confirmation feedback indicating that the second UE successfully received the first data in the first transmission, signaling the first UE to retransmit the first data to the second UE via a sidelink.

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