Indication of single-stage or multi-stage sidelink control information (SCI)

Abstract

Certain aspects of the present disclosure provide techniques for wireless communication for sidelink communication by a first transmitting user equipment (UE) with a second receiving UE. The techniques generally include: determining whether to transmit sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to the receiving UE in one phase or in multiple phases, transmitting the SCI based on the determination, and transmitting the PSSCH based on the SCI. Release 16 NR sidelink transmissions typically include two (or more) phases of SCI. The present disclosure provides methods and techniques for alternative mechanisms to achieve goals similar to multiple phases of SCI in the absence of a second (and subsequent) SCI phase.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Application No. 17 / 204,695, filed on March 17, 2021, which claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 022,334, filed on May 8, 2020, which are assigned to the assignee of the present application, and are hereby incorporated by reference in their entirety as set forth below for all applicable purposes. Technical Field

[0003] Aspects of the present disclosure relate to wireless communication, and more particularly, to device - to - device sidelink communication. Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasting, 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 the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system, LTE - Advanced (LTE - A) system, Code Division Multiple Access (CDMA) system, Time Division Multiple Access (TDMA) system, Frequency Division Multiple Access (FDMA) system, Orthogonal Frequency Division Multiple Access (OFDMA) system, Single - Carrier Frequency Division Multiple Access (SC - FDMA) system, and Time Division Synchronous Code Division Multiple Access (TD - SCDMA) system, to name a few.

[0005] In some examples, a wireless multiple access communication system may include multiple base stations (BSs), each BS capable of supporting communication with a plurality of communication devices (also referred to as user equipment (UEs)) simultaneously. In an LTE or LTE - A network, a collection of one or more base stations may define an evolved Node B (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), transmit - receive points (TRPs), etc.) communicating with multiple central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a collection 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 Node B (gNB or gNodeB), transmit - receive point (TRP), etc.). The BS or DU may communicate with a set of UEs on a downlink channel (e.g., for transmission from the BS or DU to the UE) and an uplink channel (e.g., for transmission from the UE to the BS or DU).

[0006] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at the city, national, regional, and even global levels. NR (e.g., New Radio or 5G) is an example of an emerging telecommunication standard. NR is an enhanced set of the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, reducing costs, enhancing services, leveraging new spectrums, and using OFDMA with cyclic prefix (CP) on the 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.

[0007] Sidelink communication is communication from one UE to another UE. As the demand for mobile broadband access continues to grow, further improvements to NR and LTE technologies are needed, including improvements to sidelink communication. Preferably, these improvements should be applicable to other multiple access technologies and telecommunication standards that employ these technologies. SUMMARY OF THE INVENTION

[0008] The systems, methods, and devices of the present disclosure each have several aspects, none of which alone is 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, particularly after reading the section entitled "DETAILED DESCRIPTION," one will understand how the features of the present disclosure provide advantages, including device-to-device communication in a wireless network.

[0009] Certain aspects of the present disclosure provide a method for wireless communication for sidelink communication from a first transmitting user equipment (UE) to a second receiving UE. The method generally includes: determining whether to send sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to the receiving UE in one phase or multiple phases, sending the SCI based on the determination, and sending the PSSCH based on the SCI. Release 16 NR sidelink transmissions typically include two (or more) phases of SCI. The present disclosure provides methods and techniques for alternative mechanisms to achieve similar goals to multiple phases of SCI in the absence of the second (and subsequent) SCI phases. For example, different schemes are disclosed herein to (1) indicate the number of SCI phases; and (2) carry the information of other SCI phases in cases where their information would be available if they were actually absent. Thus, unnecessary SCI overhead can be saved by having a single-phase SCI in some cases.

[0010] Certain aspects of the present disclosure provide a method for wireless communication by a receiving UE. The method generally includes: determining whether to receive sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission from a transmitting UE in one phase or in multiple phases, processing the SCI based on the determination, and decoding the PSSCH based on the SCI.

[0011] Certain aspects of the present disclosure provide a method for wireless communication by a network entity. The method generally includes: determining whether a first UE is to send sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to a second UE in one phase or in multiple phases, and providing an indication to at least one of the first UE or the second UE as to whether the first UE is to send the SCI in one phase or in multiple phases.

[0012] Aspects of the present disclosure provide components, apparatuses, processors, and computer-readable media for performing the methods described herein.

[0013] To achieve the foregoing and related purposes, one or more aspects include the features that are fully described hereinafter and particularly pointed out in the claims. The following description and the drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are merely indicative of the many ways in which the principles of the various aspects may be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To enable a more particular understanding of the above-described features of the present disclosure, a more specific description may be had by reference to the aspects, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain typical aspects of the present disclosure and are therefore not to be considered limiting of its scope, for the description may admit of other equally effective aspects.

[0015] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0016] Figure 2 is a block diagram illustrating an example logical architecture of a distributed radio access network (RAN) in accordance with certain aspects of the present disclosure.

[0017] Figure 3 is a diagram illustrating an example physical architecture of a distributed RAN in accordance with certain aspects of the present disclosure.

[0018] Figure 4 is a block diagram conceptually illustrating the design of an example base station (BS) and user equipment (UE) in accordance with certain aspects of the present disclosure.

[0019] Figure 5A and Figure 5B illustrates a diagrammatic representation of an example vehicle-to-everything (V2X) system in accordance with some aspects of the present disclosure.

[0020] Figure 6 illustrates an example of a two-stage SCI for sidelink communication in accordance with certain aspects of the present disclosure.

[0021] Figure 7 illustrates an example operation for wireless communication by a first transmitting UE in accordance with certain aspects of the present disclosure.

[0022] Figure 8 illustrates an example operation for wireless communication by a second receiving UE in accordance with certain aspects of the present disclosure.

[0023] Figure 9 illustrates an example operation for wireless communication by a network entity in accordance with certain aspects of the present disclosure.

[0024] Figure 10 illustrates a communication device that may include various components configured to perform the operations shown in Figure 7 in accordance with certain aspects of the present disclosure.

[0025] Figure 11 illustrates a communication device that may include various components configured to perform the operations shown in Figure 8 in accordance with certain aspects of the present disclosure.

[0026] Figure 12 illustrates a communication device that may include various components configured to perform the operations shown in Figure 9 in accordance with certain aspects of the present disclosure.

[0027] For ease of understanding, wherever possible, the same reference numerals are used to denote the same elements in the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized in other aspects without specific recitation. Detailed Description

[0028] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for determining and / or indicating one or more stages of sidelink control information (SCI). The SCI in NR V2X Release 16 may include two stages: SCI-1 and SCI-2. Decoding SCI-2 may require SCI-1; and decoding the physical sidelink shared channel (PSSCH) may require both SCI-1 and SCI-2. The two-stage SCI design may (1) cause error propagation between SCI-1 detection and SCI-2 decoding; and (2) incur unnecessary SCI overhead, among other issues.

[0029] In some aspects of the present disclosure, the UE determines whether to send the SCI for decoding the PSSCH transmission in one phase or in multiple phases, and in some cases, sends the SCI in a single phase (e.g., SCI-1), and uses an alternative mechanism to carry control or information that would otherwise be carried via other SCI phases (e.g., SCI-2).

[0030] The following description provides examples and does not 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 the present disclosure. Various examples may appropriately omit, substitute, or add various processes or components. For example, the methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, 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 the apparatus or practice the method. Moreover, the scope of the present disclosure is intended to cover such apparatus or methods that practice using other structures, functions, or structures and functions in addition to 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 “serving as an example, instance, or illustration”. Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or superior to other aspects.

[0031] The techniques described herein may 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. CDMA networks may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. Cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks may implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks may 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, Fast-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS).

[0032] New Radio (NR) is an emerging wireless communication technology being developed together with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and LTE-Advanced (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 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 techniques described herein can be used in the wireless networks and radio technologies mentioned above and 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 aspects, aspects of the present disclosure can be applied to other generation-based communication systems, such as 5G and later technologies, including NR technology.

[0033] New Radio (NR) access (e.g., 5G technology) can support various wireless communication services, such as enhanced mobile broadband (eMBB) targeted at wide bandwidth (e.g., 80 MHz or above), millimeter wave (mmW) targeted at high carrier frequencies (e.g., 25 GHz or above), massive machine type communication MTC (mMTC) targeted at non-backward compatible MTC technology, and / or mission critical targeted at ultra-reliable low latency communication (URLLC). These services may include latency as well as 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 can coexist in the same subframe.

[0034] Figure 1 FIG. illustrates an example wireless communication network 100 in which aspects of the present disclosure can be performed. For example, Figure 1 one or more UEs 120a can be configured to perform the operations described below with reference to Figure 7 to determine whether to send the SCI for PSSCH transmission in one phase or multiple phases, or the operations described below with reference to Figure 8 to determine how to process the SCI (and the corresponding physical sidelink shared channel). Similarly, the base station 110 can be configured to perform Figure 9 operation 900 to provide an indication of whether the SCI should be sent in one phase or multiple phases.

[0035] As Figure 1As shown, the wireless communication network 100 may include multiple base stations (BSs) 110a - 110z (each also referred to herein individually as BS 110 or collectively as BS 110) and other network entities. In aspects of the present disclosure, a roadside service unit (RSU) may be considered a type of BS, and BS 110 may be referred to as an RSU. BS 110 may provide communication coverage for a specific geographical area (sometimes referred to as a “cell”), which may be fixed or may move according to the location of the mobile BS 110. In some examples, BS 110 may use any suitable transmission network to interconnect with each other and / or interconnect to one or more other BSs or network nodes (not shown) in the wireless communication network 100 through various types of backhaul interfaces (e.g., direct physical connection, wireless connection, virtual network, etc.). In Figure 1 the example shown, BSs 110a, 110b, and 110c may be macro BSs of macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS of pico cell 102x. BSs 110y and 110z may be femto BSs of femto cells 102y and 102z, respectively. A BS may support one or more cells. BS 110 communicates with user equipment (UEs) 120a - 120y (each also referred to herein individually as UE 120 or collectively as UE 120) in the wireless communication network 100. UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE 120 may be fixed or mobile.

[0036] According to certain aspects, UE 120 may be configured to determine resources for sidelink communication (with another UE). As Figure 1 shown, UE 120a includes a sidelink manager 122. The sidelink manager 122 may be configured to send sidelink communication (or process such sidelink communication) to another UE according to aspects of the present disclosure.

[0037] The wireless communication network 100 may also include a relay station (e.g., relay station 110r) (also referred to as a relay, etc.), which receives a transmission of data and / or other information from an upstream station (e.g., BS 110a or UE 120r) and sends the transmission of the data and / or other information to a downstream station (e.g., UE 120 or BS 110), or relays transmissions between UEs 120 to facilitate communication between devices.

[0038] The network controller 130 may be coupled to a set of BSs 110 and provide coordination and control for these BSs 110. The network controller 130 may communicate with BS 110 via the backhaul. BS 110 may also communicate with each other via wireless or wired backhaul (e.g., directly or indirectly).

[0039] UE 120 (e.g., 120x, 120y, etc.) can be dispersed throughout the wireless communication network 100, and each UE can be fixed or mobile. A UE can also be referred to as a mobile station, a terminal, an access terminal, a user unit, a station, a customer premise equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smart book, an ultrabook, an appliance, a medical device or equipment, a biosensor / device, a wearable device (such as a smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicle component or sensor, a smart meter / sensor, an industrial manufacturing device, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs can 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 to a network (e.g., a wide area network such as the Internet or a cellular network) or provide connectivity to the network via a wired or wireless communication link. Some UEs can be considered as Internet of Things (IoT) devices, which can be narrowband IoT (NB-IoT) devices.

[0040] 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 typically also referred to as tones, bins, etc. Each subcarrier can be modulated with data. Generally, modulated 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 can be 15 kHz, and the minimum resource allocation (referred to as a "resource block" (RB)) can be 12 subcarriers (or 180 kHz). Thus, 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 can also be divided into subbands. For example, a subband can cover 1.8 MHz (i.e., 6 resource blocks), and for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, there can be 1, 2, 4, 8, or 16 subbands, respectively.

[0041] Although aspects of the examples described herein can be associated with LTE technology, aspects of the present disclosure can be applicable to other wireless communication systems, such as NR. NR can use OFDM with a cyclic prefix (CP) on both the uplink and the downlink and includes support for half-duplex operation using TDD. Beamforming can be supported, and the beam direction can be dynamically configured. MIMO transmission with precoding can also be supported. The MIMO configuration in the DL can support up to 8 transmit antennas, with up to 8 layers of DL transmission and up to 2 streams per UE. Multilayer transmission with up to 2 streams per UE can be supported. Aggregation of multiple cells can be supported with up to 8 serving cells.

[0042] In some examples, access to an air interface can be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication between some or all of the devices and equipment within its serving 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, the subordinate entities utilize the resources allocated by the scheduling entity. A 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 the other UEs can utilize the resources scheduled by the UE for wireless communication. In some examples, a UE can 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 the scheduling entity, UEs can communicate directly with each other.

[0043] In Figure 1 it, the solid line with double arrows represents the desired transmission between the UE and the serving BS, which is the BS designated to serve the UE on the downlink and / or uplink. The thin dashed line with double arrows represents the interfering transmission between the UE and the BS.

[0044] Figure 2 illustrates an example logical architecture of a distributed radio access network (RAN) 200, which can be implemented in the wireless communication network 100 shown in Figure 1 it. The 5G access node 206 can include an access node controller (ANC) 202. The ANC 202 can be the central unit (CU) of the distributed RAN 200. The backhaul interface to the next-generation core network (NG-CN) 204 can terminate at the ANC 202. The backhaul interface to an adjacent next-generation access node (NG-AN) 210 can terminate at the ANC 202. The ANC 202 can include one or more TRPs 208 (e.g., cells, BSs, gNBs, etc.).

[0045] The TRP 208 can be a distributed unit (DU). The TRP 208 can be connected to a single ANC (e.g., ANC 202) or more than one ANC (not shown). For example, for RAN sharing, radio as a service (RaaS), and service-specific AND deployments, the TRP 208 can be connected to more than one ANC. Each TRP 208 can include one or more antenna ports. The TRP 208 can be configured to provide services to the UE individually (e.g., dynamically select) or jointly (e.g., joint transmission).

[0046] The logical architecture of the distributed RAN 200 can support fronthaul solutions across different deployment types. For example, the logical architecture can be based on the transmitting network capabilities (e.g., bandwidth, latency, and / or jitter).

[0047] The logical architecture of the distributed RAN 200 can share features and / or components with LTE. For example, the next-generation access node (NG-AN) 210 can support dual connectivity with NR and can share a common fronthaul for LTE and NR.

[0048] The logical architecture of the distributed RAN 200 can enable cooperation between TRPs 208, e.g., via the ANC 202 within and / or across TRPs. An inter-TRP interface may not be used.

[0049] The logical functions can be dynamically distributed in the logical architecture of the distributed RAN 200. The radio resource control (RRC) layer, packet data convergence protocol (PDCP) layer, radio link control (RLC) layer, media access control (MAC) layer, and physical (PHY) layer can be placed adaptively at the DU (e.g., TRP 208) or CU (e.g., ANC 202).

[0050] Figure 3 FIG. illustrates an example physical architecture of a distributed RAN 300 in accordance with aspects of the present disclosure. A centralized core network unit (C-CU) 302 can host core network functions. The C-CU 302 can be centrally deployed. The C-CU 302 functions can be offloaded (e.g., to an advanced wireless service (AWS)) to attempt to handle peak capacity.

[0051] A centralized RAN unit (C-RU) 304 can host one or more ANC functions. Optionally, the C-RU 304 can locally host core network functions. The C-RU 304 can have a distributed deployment. The C-RU 304 can be close to the network edge.

[0052] The DU 306 can host one or more TRPs (edge node (EN), edge unit (EU), radio head (RH), smart radio head (SRH), etc.). The DU can be located at the edge of the network with radio frequency (RF) capabilities.

[0053] Figure 4 FIG. illustrates example components of a (e.g., as described in Figure 1 BS110a and UE120a that can be used to implement aspects of the present disclosure. For example, the antenna 452, processors 466, 458, 464, and / or controller / processor 480 of the UE 120a can be used to perform the operations described herein with reference to Figure 7 and / or Figure 8The various techniques and methods described. Similarly, the antennas 434, processors 420, 438, 430, and / or controller / processor 440 of BS110a can be used to perform the various techniques and methods referred to herein Figure 9 described.

[0054] At BS110a, the transmit processor 420 can receive data from the data source 412 and control information from the controller / processor 440. 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 (GC PDCCH), etc. The data can be used for the physical downlink shared channel (PDSCH), etc. The processor 420 can process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 420 can also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). The transmit (TX) multiple-input multiple-output (MIMO) processor 430 can perform spatial processing (e.g., precoding) on the data symbols, control symbols, and / or reference symbols, when applicable, and can provide the output symbol streams to the modulators (MOD) 432a to 432t. Each modulator 432 can process its respective 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 signals from the modulators 432a to 432t can be transmitted via the antennas 434a to 434t, respectively.

[0055] At UE 120a, the antennas 452a to 452r can receive the downlink signals from the base station 110a and can provide the received signals to the demodulators (DEMOD) in the transceivers 454a to 454r, respectively. Each demodulator 454 can condition (e.g., filter, amplify, down-convert, and digitize) its respective received signal to obtain an input sample. Each demodulator can further process the input sample (e.g., for OFDM, etc.) to obtain received symbols. The MIMO detector 456 can obtain the received symbols from all the demodulators in the transceivers 454a to 454r, perform MIMO detection on the received symbols, when applicable, and provide the detected symbols. The receive processor 458 can process (e.g., demodulate, de-interleave, and decode) the detected symbols, provide the decoded data for UE120a to the data sink 460, and provide the decoded control information to the controller / processor 480.

[0056] On the uplink, at UE 120a, transmit processor 464 may receive and process data from data source 462 (e.g., for physical uplink shared channel (PUSCH)) and control information from controller / processor 480 (e.g., for physical uplink control channel (PUCCH)). Transmit processor 464 may also generate reference symbols for reference signals (e.g., for sounding reference signal (SRS)). Symbols from transmit processor 464 may be precoded by TX MIMO processor 466 when applicable, further processed by demodulators in transceivers 454a to 454r (e.g., for SC-FDM, etc.), and transmitted to base station 110a. At BS110a, the uplink signal from UE 120a may be received by antenna 434, processed by modulator 432, detected by MIMO detector 436 when applicable, and further processed by receive processor 438 to obtain the decoded data and control information transmitted by UE 120a. Receive processor 438 may provide the decoded data to data sink 439 and the decoded control information to controller / processor 440.

[0057] Controller / processors 440 and 480 may direct operations at BS110a and UE 120a, respectively. Processor 440 and / or other processors and modules at BS110a may execute or direct the execution of procedures for the techniques described herein. As Figure 2 shown, controller / processor 480 of UE 120a has a sidelink manager 481, which may be configured to send sidelink communications to another UE (or to process such sidelink communications). Although shown at controller / processor 480 and controller / processor 440, other components of UE 120a and BS110a may be used to perform the operations described herein. Memories 442 and 482 may store data and program codes for BS110a and UE 120a, respectively. Scheduler 444 may schedule data transmissions for the UE on the downlink, sidelink, and / or uplink.

[0058] In some cases, two or more subordinate entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of these sidelink communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communication, Internet of Everything (IoE) communication, IoT communication, mission-critical grids, and / or various other suitable applications. Generally, a sidelink signal may refer to a signal transmitted from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying the communication through a scheduling entity (e.g., UE or BS), even though the scheduling entity may be used for scheduling and / or control purposes. In some examples, licensed spectrum may be used to transmit sidelink signals (different from wireless local area networks which typically use unlicensed spectrum).

[0059] Figure 5A and Figure 5B FIG. illustrates a graphical representation of an example vehicle-to-everything (V2X) system in accordance with some aspects of the present disclosure. For example, Figure 5A and Figure 5B the vehicles shown in may communicate via a sidelink channel and may perform sidelink CSI reporting as described herein.

[0060] Figure 5A and Figure 5B The V2X system provided in provides two complementary transmission modes. In Figure 5A The first transmission mode, shown as an example in, involves direct communication between participants in a local area that are in close proximity to each other (e.g., also referred to as sidelink communication). In Figure 5B The second transmission mode, shown as an example in, involves network communication through a network, which may be implemented via the Uu interface (e.g., a wireless communication interface between a radio access network (RAN) and a UE).

[0061] Referring to Figure 5A , FIG. illustrates a V2X system 500 (e.g., including vehicle-to-vehicle (V2V) communication) having two vehicles 502, 504. The first transmission mode allows direct communication between different participants in a given geographical location. As shown, a vehicle may have a wireless communication link 506 with a person through the PC5 interface (i.e., vehicle-to-person (V2P) via a UE, for example). Communication between vehicles 502 and 504 may also occur through the PC5 interface 508. In a similar manner, communication from vehicle 502 to other highway components (e.g., roadside service unit 510), such as traffic signals or signs (i.e., vehicle-to-infrastructure (V2I)), may occur through the PC5 interface 512. Regarding Figure 5AEach of the communication links shown can enable two-way communication between components, so each component can be a transmitter and receiver of information. The V2X system 500 can be a self-managed system implemented without assistance from a network entity. The self-managed system can achieve improved spectral efficiency, reduced costs, and increased reliability because there is no network service interruption during handover operations for mobile vehicles. The V2X system can be configured to operate in licensed or unlicensed spectrum, so any vehicle equipped with the system can access a common frequency and share information. Such coordinated / common spectrum operation allows for safe and reliable operation.

[0062] Figure 5B A V2X system 550 is shown for communicating between a vehicle 552 and a vehicle 554 via a network entity 556. These network communications can occur via discrete nodes (such as base stations (e.g., eNB or gNB)) that send information to and receive information from the vehicles 552, 554 (e.g., relay information between the vehicles 552, 554). Network communications via vehicle-to-network (V2N) links 558 and 510 can be used for, e.g., long-range communication between vehicles, such as to convey the presence of a car accident a certain distance ahead along a road or highway. The nodes can send other types of communications to the vehicles, such as traffic flow conditions, road hazard warnings, environmental / weather reports, and service station availability, etc. Such data can be obtained from cloud-based shared services.

[0063] In some cases, two or more subordinate entities (e.g., UEs) can communicate with each other using sidelink signals. As described above, V2V and V2X communications are examples of communications that can be sent via sidelink. When a UE is transmitting sidelink communication on a subchannel of a frequency band, the UE generally cannot receive another communication (e.g., another sidelink communication from another UE) in that frequency band. Other applications of sidelink communication can include public safety or service announcement communication, communication for proximity services, communication for UE-to-network relay, device-to-device (D2D) communication, Internet of Everything (IoE) communication, Internet of Things (IoT) communication, mission-critical mesh communication, and other suitable applications. Generally, sidelink can refer to a direct link between one subordinate entity (e.g., UE1) and another subordinate entity (e.g., UE2). Thus, sidelink can be used to send and receive communications (also referred to herein as "sidelink signals") without relaying the communication through a scheduling entity (e.g., BS), even though the scheduling entity can be used for scheduling or control purposes. In some examples, sidelink signals can be transmitted using licensed spectrum (different from wireless local area networks that typically use unlicensed spectrum).

[0064] Various sidelink channels can be used for sidelink communication, including the Physical Sidelink Discovery Channel (PSDCH), Physical Sidelink Control Channel (PSCCH), Physical Sidelink Shared Channel (PSSCH), and Physical Sidelink Feedback Channel (PSFCH). The PSDCH can carry discovery expressions that enable nearby devices to discover each other. The PSCCH can carry control signaling, such as sidelink resource configuration and other parameters for data transmission, and the PSSCH can carry data transmission.

[0065] For operations regarding the PSSCH, the UE performs transmission or reception on a carrier in a time slot. Transmission resources for sidelink transmission are typically reserved or allocated on sub-channels of a frequency band during a period of the time slot. NR sidelink supports the UE in one case where all symbols in a time slot are available for the sidelink, and in another case where only a subset of consecutive symbols in a time slot are available for the sidelink.

[0066] The PSFCH can carry feedback, such as channel state information (CSI) related to the sidelink channel quality. A sequence-based PSFCH format with one symbol (excluding the AGC training period) can be supported. The following formats can be possible: a PSFCH format based on PUCCH format 2 and a PSFCH format spanning all available symbols in a time slot for the sidelink.

[0067] Examples of single-stage or multi-stage sidelink control information (SCI) indication

[0068] Aspects of the present disclosure provide techniques that can help save SCI overhead when multi-stage SCI is not required. Different schemes are proposed to indicate the presence or absence of multi-stage SCI, such as second-stage SCI (SCI-2). Even when there is a single-stage SCI (SCI-1) and no SCI-2, alternative mechanisms can still be used to carry information or content that would otherwise be carried in SCI-2.

[0069] As will be described in more detail below, the transmitting UE can determine whether to send SCI for decoding PSSCH transmission to the receiving UE in one stage or in multiple stages. Then, the transmitting UE sends the SCI based on this determination and sends the PSSCH based on the SCI. As a result, the transmitting UE can determine to send SCI-1 without sending SCI-2, thereby saving SCI overhead.

[0070] As will be described in more detail, one or more phases of SCI determination can be performed in sidelink communication in mode 1 or mode 2. For example, in mode 1, a network entity can determine whether a first UE is to send an SCI for decoding a PSSCH transmission to a second UE in one phase or in multiple phases. The network entity can provide an indication to at least one of the first UE or the second UE as to whether the first UE is to send the SCI in one phase or in multiple phases.

[0071] Figure 6 Illustrated is an example two-phase SCI 600 for sidelink communication in which aspects of the present disclosure can be practiced. Although Figure 6 the example shows two phases, the techniques presented herein can generally be applied to any number of multiple phases.

[0072] As shown, a first SCI phase (SCI-1) can be sent on the PSCCH and contains information for resource allocation. SCI-1 can contain information for decoding SCI-2. SCI-2 can be sent on the PSSCH and contains information for decoding data (SCH). Both SCI-1 and SCI-2 can use PDCCH polar codes.

[0073] As described above, NR sidelink generally has two resource allocation modes: mode 1 and mode 2. In mode 1, sidelink resources are scheduled by the gNB. In mode 2, a UE can select sidelink resources from a sidelink resource pool based on a channel sensing mechanism.

[0074] Due to the need for resource sensing, not all fields of the SCI can be sent in a single phase. Multi-phase SCIs (such as SCI-1 and SCI-2) can be sent separately. SCI-1 can carry information about PSSCH resources and information for decoding SCI-2, including priority (QoS value), time-frequency resources of the PSSCH / PSFCH, resource reservation period, PSSCH DMRS mode, SCI-2 format, 2-bit beta offset for second-phase control resource allocation, PSSCH DMRS port number, etc.

[0075] SCI-2 can carry the remaining scheduling information for PSSCH decoding by the receiving UE, such as, for example, source ID, destination ID, channel state information (CSI) report trigger (unicast), modulation and coding scheme (MCS), UE-specific demodulation reference signal (DMRS), new data indicator (NDI), redundancy version (RV), hybrid automatic repeat request (HARQ) process ID, region ID of the transmitter, and maximum communication range of NACK (multicast), etc.

[0076] It can be expected to switch between single-stage and multi-stage SCI schemes. To this end, the sending UE and the receiving UE can coordinate regarding the number of stages. For example, since SCI-2 decoding may require information in SCI-1, and data (PSSCH) decoding requires information in both SCI-1 and SCI-2.

[0077] Aspects of the present disclosure provide various techniques for indicating the number of SCI stages. For example, these techniques can indicate the presence or absence of SCI-2, and if SCI-2 is absent, convey the information that would otherwise be conveyed in SCI-2 via an alternative mechanism.

[0078] Figure 7 、 Figure 8 and Figure 9 Illustrate example operations for these techniques from the perspectives of the sending UE, the receiving UE, and the network entity, respectively.

[0079] Figure 7 Illustrates an example operation 700 for wireless communication by a first sending UE according to certain aspects of the present disclosure. For example, when performing sidelink communication with a receiving UE (which can be Figure 1 or Figure 4 another UE 120), operation 700 can be performed by Figure 1 or Figure 4 the UE 120.

[0080] Operation 700 begins at 702 by determining whether to send an SCI for decoding a PSSCH transmission to the receiving UE in one stage or in multiple stages. This determination can be based on different aspects in different options. For example, this determination can be based on a configuration (by the network entity or via sidelink) indicating one or more stages for sending the SCI. In another option, it is determined whether to send the SCI in one stage or in multiple stages based on downlink control information (DCI) transmitted from the network entity to the sending UE. Details of these options and other options are discussed further below.

[0081] At 704, the sending UE sends the SCI according to the determination at 702. For example, the sending UE can send a single-stage or multi-stage SCI to the receiving UE based on the configuration or DCI or other determining factors.

[0082] At 706, the sending UE can send the PSSCH according to the SCI. For example, if previously so determined, a single-stage SCI will be sufficient for the receiving UE to decode the PSSCH sent in this step.

[0083] Figure 8Illustrates example operation 800 for wireless communication by a receiving UE, which may be considered complementary to Figure 7 operation 700 of Figure 1 or Figure 4 Another UE 120 of Figure 7 performs operation 800 for the process SCI sent by the UE that performs operation 700 of

[0084] Operation 800 begins at 802 by determining whether to receive the SCI for decoding the PSSCH transmission from the sending UE in one phase or in multiple phases. For example, this determination may correspond to various options based on configuration or DCI, as discussed with respect to the sending UE.

[0085] At 804, the receiving UE processes the SCI according to this determination. For example, the receiving UE receives a single-phase or multi-phase SCI from the sending UE according to the previous determination and processes the received SCI.

[0086] At 806, the receiving UE decodes the PSSCH according to the SCI.

[0087] As mentioned above, Release 16 has introduced two-phase SCI, and future releases may allow additional SCI phases (e.g., three or more phases). In the example of Figure 6 SCI-1 and SCI-2 carry different information. Thus, determining one or more phases to send (e.g., at 702 and 802 respectively) may also include: determining an alternative mechanism for sending information that would otherwise be carried when there is no multi-phase SCI (i.e., when a single-phase SCI is determined). Example alternative mechanisms are discussed below. In some implementations, each SCI phase in one or more SCI phases involves sending the SCI in a single packet.

[0088] In one option, the determination may be based on a configuration indicating one or more phases for sending the SCI. For example, the configuration indicates that the number of SCI phases is one or two. This configuration may be conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling. For example, this configuration may be received from a network entity (such as in mode 1 of sidelink transmission). In other cases, this configuration may be conveyed via sidelink RRC. The MAC CE may be a sidelink MAC CE.

[0089] In some aspects, the configuration may expire within a set time period or until a further configuration is received. For example, when the configuration is time-limited, the configuration may apply to the next set number of subframes or the next set number of instances or periods of a resource pool. In other cases, the configuration may remain until changed.

[0090] In some embodiments, an indication of whether the SCI is being sent in one phase or in multiple phases may be provided to the receiving UE in the first SCI transmission. For example, the transmitting UE may use the first SCI transmission to indicate the presence or absence of a second (or more) SCI transmission. In some cases, based on the format of the first SCI or the value of one or more fields in the SCI, the indication may be implicit in the first SCI transmission. In some cases, the SCI format itself may be RRC-configured. For example, the first SCI may indicate a size of PSSCH resource allocation that is insufficient to provide a second SCI, thus indicating the absence of any subsequent transmissions. In some cases, the implicit indication may be based on the destination address. For example, in a relay scenario, if a packet is sent from A to B and is destined for B, the second SCI is not sent. By comparison, if the packet is destined for C, B may read the second SCI to determine the authorization parameters for the transmission from B to C.

[0091] In other cases, the first SCI may provide an explicit field or bit to indicate the presence of a second or subsequent SCI, e.g., using a "SCI-2 present" field.

[0092] In another option, it is determined whether to send the SCI in one phase or in multiple phases based on the downlink control information (DCI) sent from the radio network entity to the transmitting UE. In some embodiments, the radio network entity notifies the receiving UE about the SCI phase determination. For example, in mode 1, the authorization DCI may tell the sidelink transmitting UE to transmit only SCI-1. This determination may be notified to the sidelink receiving UE according to the various embodiments given herein. Additionally or alternatively, the radio network may transmit a "mode 1 Rx authorization" or a similar indication to the receiving UE to notify the receiving UE.

[0093] In other embodiments, the determination may be applied to sidelink communications per link, per resource pool, or per specific subset of resource pools. For example, the determination may be applied based on one or more of time domain allocation (e.g., slot or subframe index), frequency domain allocation (e.g., subchannel index), or spatial allocation (e.g., beam index).

[0094] Although the above-described multiple phases are shown using SCI-1 and SCI-2, third, fourth, and subsequent SCI phases can be configured, determined, and indicated according to various embodiments of the present disclosure. For example, the third SCI phase can carry additional information for SCI-2 (e.g., relay authorization for use in the next hop). The presence or absence of the third SCI can be indicated in a combination of RRC and the indication in SCI-1 and SCI-2. Similarly, the disclosed method is applicable to the multi-packet case. For example, SCI-2 can be split into multiple parts, and the indication of the SCI phase can be applied to the same number of multiple subframes corresponding to the number of the multiple parts of the split SCI-2.

[0095] When there is no second or subsequent SCI phase, sidelink communication can still utilize a single-phase SCI to carry the information that would be carried in the multi-phase SCI case. For example, when the transmitting UE determines to transmit the SCI in a single phase, the single-phase SCI can include the information that would be carried in at least the second phase if the SCI were transmitted in multiple phases. For example, the single-phase SCI can include a new field to carry the information that would be carried. Alternatively, the single-phase SCI can reuse a field for indicating the second SCI phase or a combination of new fields and reuse a field for indicating the second SCI phase.

[0096] In some cases, the single-phase SCI can include fields for one or more of the following: new data indicator (NDI), hybrid automatic repeat request (HARQ) process identifier (Id), source ID, destination ID, or CSI report trigger. In other cases, the information that would be carried in at least the second phase if the SCI were conveyed in multiple phases is conveyed via RRC or MAC CE signaling. For example, since RRC, MAC CE, or DCI can indicate the absence of the second or subsequent SCI, RRC, MAC CE, or DCI can also specify the information that might be carried in the second or subsequent SCI.

[0097] In some cases, the information that would be carried in at least the second phase if the SCI were transmitted in multiple phases is implicitly derived from the information in the single-phase SCI. For example, the HARQ process ID can be derived from the time slot or subframe number.

[0098] In other cases, a default value for an assumption of information that would be carried in at least a second phase if the SCI were sent in multiple phases is derived from the information in a single-phase SCI. For example, in the Uu link, some fields of a second SCI that would be sent can be supported only in long DCIs, so comparing a short DCI with a long DCI can indicate the default value (e.g., format 0_0 versus 0_1 for uplink, or format 1_0 versus 1_1 for downlink). A similar approach can be applied to the default maximum communication range for group-based NACKs. In other instances, the codeblock group (CBG) transmission information or CBG flushing information (CBGTI / CBGFI) fields are not in the short DCI because CBG-based HARQ is not supported in the short DCI. Similarly, if the maximum communication range field is missing in the absence of a second SCI phase, distance-based NACKs may not be supported.

[0099] As described above, in some cases, a network entity can indicate to the sending UE, the receiving UE, or both whether the SCI is to be sent in one phase or in multiple phases.

[0100] Figure 9 Illustrated is an example operation 900 for wireless communication by a network to provide such an indication. For example, operation 900 can be performed by Figure 5A and Figure 5B wireless network entity 556 (which can be Figure 1 or Figure 4 base station 110) when supporting sidelink communication between a sending UE and a receiving UE, such as operations 700 and 800 described above.

[0101] Operation 900 begins at 902 by determining whether the sending UE is to send the SCI for decoding a PSSCH transmission to the receiving UE in one phase or in multiple phases. At 904, the wireless network entity can provide an indication to at least one of the sending UE or the receiving UE as to whether the sending UE is to send the SCI in one phase or in multiple phases. As mentioned above, the indication can be provided via DCI, which can include at least one of the following: a transmission authorization for the sending UE, or a reception authorization for the receiving UE.

[0102] Figure 10 Illustrated is a communication device 1000 that can include circuitry configured to perform operations for the techniques disclosed herein, such as Figure 7the various components (e.g., corresponding to component-plus-function components) of the operations shown). The communication device 1000 includes a processing system 1002 coupled to a transceiver 1008. The transceiver 1008 is configured to transmit and receive signals for the communication device 1000 via an antenna 1010, such as the various signals described herein. The processing system 1002 may be configured to perform the processing functions of the communication device 1000, including processing signals received and / or transmitted by the communication device 1000.

[0103] 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 7 the operations shown, or other operations for recovering sidelink communications lost by a wireless node due to the wireless node transmitting while sidelink communications are occurring. In some aspects, the computer-readable medium / memory 1012 stores code 1014 for determining whether to send an SCI for decoding a PSSCH transmission to a receiving UE in one phase or in multiple phases; code 1016 for sending the SCI based on the determination; and code 1018 for sending the PSSCH based on the SCI. 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 1020 for determining whether to send an SCI for decoding a PSSCH transmission to a receiving UE in one phase or in multiple phases; circuitry 1022 for sending the SCI based on the determination; and circuitry 1024 for sending the PSSCH based on the SCI.

[0104] Figure 11 illustrates a communication device 1100 that may include various components (e.g., corresponding to component-plus-function components) configured to perform the operations of the techniques disclosed herein, such as Figure 8 the operations shown. The communication device 1100 includes a processing system 1102 coupled to a transceiver 1108. The transceiver 1108 is configured to transmit and receive signals for the communication device 1100 via an antenna 1110, such as the various signals described herein. The processing system 1102 may be configured to perform processing functions on the communication device 1100, including processing signals received and / or transmitted by the communication device 1100.

[0105] 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 8 the operations shown, or other operations for recovering sidelink communications lost by a wireless node due to the wireless node transmitting while sidelink communications are occurring. In some aspects, the computer-readable medium / memory 1112 stores code 1114 for determining whether to receive an SCI for decoding a PSSCH transmission from a transmitting UE in one phase or in multiple phases; code 1116 for processing the SCI based on the determination; and code 1118 for decoding the PSSCH based on the SCI. 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 1120 for determining whether to receive an SCI for decoding a PSSCH transmission from a transmitting UE in one phase or in multiple phases; circuitry 1122 for processing the SCI based on the determination; and circuitry 1124 for decoding the PSSCH based on the SCI.

[0106] Figure 12 illustrates a communication device 1200 that may include various components (e.g., corresponding to component-plus-function components) configured to perform operations for the techniques disclosed herein, such as Figure 9 the operations shown. The communication device 1200 includes a processing system 1202 coupled to a transceiver 1208. The transceiver 1208 is configured to transmit and receive signals of the communication device 1200 via an antenna 1210, such as the various signals described herein. The processing system 1202 may be configured to perform the processing functions of the communication device 1200, including processing signals received by and / or to be transmitted by the communication device 1200.

[0107] The processing system 1202 includes a processor 1204 coupled to a computer-readable medium / memory 1212 via a bus 1206. In some aspects, the computer-readable medium / memory 1212 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 1204, cause the processor 1204 to perform Figure 9The operations shown in [description], or other operations for restoring sidelink communications lost by a wireless node due to transmission by the wireless node while sidelink communications are occurring. In some aspects, the computer-readable medium / memory 1212 stores code 1214 for determining whether a first UE is to send a sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to a second UE in one phase or in multiple phases; and code 1216 for providing an indication to at least one of the first UE or the second UE as to whether the first UE is to send the SCI in one phase or in multiple phases. In some aspects, the processor 1204 has circuitry configured to implement the code stored in the computer-readable medium / memory 1212. The processor 1204 includes circuitry 1220 for determining whether a first UE is to send a SCI for decoding a PSSCH transmission to a second UE in one phase or in multiple phases; and circuitry 1222 for providing an indication to at least one of the first UE or the second UE as to whether the first UE is to send the SCI in one phase or in multiple phases.

[0108] Example aspects

[0109] Aspect 1: A method for wireless communication by a transmitting user equipment (UE), comprising: determining whether to send sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to a receiving UE in one phase or in multiple phases; sending the SCI based on the determination; and sending the PSSCH based on the SCI.

[0110] Aspect 2: The method according to aspect 1, wherein the determination is based on a configuration indicating one or more phases for sending the SCI.

[0111] Aspect 3: The method according to claim 2, wherein the configuration is conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling.

[0112] Aspect 4: The method according to claim 2 or 3, wherein the configuration is received from a network entity.

[0113] Aspect 5: The method according to claim 2 or 3, wherein the configuration is conveyed via sidelink RRC.

[0114] Aspect 6: The method according to claim 2 or 3, wherein the configuration expires within a set time period or until a further configuration is received.

[0115] Aspect 7: The method according to claim 2 or 3, wherein the configuration indicates the number of SCI phases.

[0116] Aspect 8: The method according to claim 1, further comprising: in a first SCI transmission, providing an indication to a receiving UE whether the SCI is transmitted in one phase or in multiple phases.

[0117] Aspect 9: The method according to aspect 8, wherein, based on the format of the first SCI or the value of one or more fields in the first SCI, the indication is implicit in the first SCI transmission.

[0118] Aspect 10: The method according to aspect 9, wherein the implicit indication is based on a destination address.

[0119] Aspect 11: The method according to aspect 8, wherein the first SCI includes an explicit indication whether the SCI is transmitted in one phase or in multiple phases.

[0120] Aspect 12: The method according to aspect 1 or 2, wherein the determination is based on downlink control information (DCI) transmitted from a radio network entity to a transmitting UE.

[0121] Aspect 13: The method according to aspect 12, wherein the radio network entity notifies the receiving UE about the SCI phase determination.

[0122] Aspect 14: The method according to aspect 1, wherein the determination is applied to sidelink communication per link, per resource pool, or per specific subset of a resource pool.

[0123] Aspect 15: The method according to aspect 1, wherein the determination is to transmit the SCI in a single phase.

[0124] Aspect 16: The method according to aspect 15, wherein the single-phase SCI includes information that would be carried in at least a second phase if the SCI is transmitted in multiple phases.

[0125] Aspect 17: The method according to aspect 15, wherein the single-phase SCI includes one or more fields of the following: a new data indicator (NDI), a hybrid automatic repeat request (HARQ) process identifier (ID), a source ID, a destination ID, or a channel state information (CSI) report trigger.

[0126] Aspect 18: The method according to aspect 15, wherein information that would be carried in at least a second phase if the SCI is transmitted in multiple phases is conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling.

[0127] Aspect 19: The method according to aspect 15, wherein information that would be carried in at least a second phase if the SCI is transmitted in multiple phases is derived from the information in the single-phase SCI.

[0128] Aspect 20: The method as described in aspect 15, wherein a default value of an assumption regarding information that would be carried in at least a second phase if the SCI were sent in multiple phases is derived from information in a single-phase SCI.

[0129] Aspect 21: The method as described in aspect 1, wherein each SCI phase among one or more SCI phases involves sending the SCI in a single packet.

[0130] Aspect 22: A method for wireless communication by a receiving user equipment (UE), comprising: determining whether to receive sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission from a transmitting UE in one phase or in multiple phases; processing the SCI according to the determination; and decoding the PSSCH according to the SCI.

[0131] Aspect 23: The method as described in aspect 22, wherein the determination is based on a configuration indicating one or more phases for sending the SCI.

[0132] Aspect 24: The method as described in aspect 23, wherein the configuration is conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling.

[0133] Aspect 25: The method as described in aspect 24, wherein the configuration is received from a network entity.

[0134] Aspect 26: The method as described in aspect 24, wherein the configuration is conveyed via sidelink RRC.

[0135] Aspect 27: The method as described in aspect 23, wherein the configuration expires within a set time period or until a further configuration is received.

[0136] Aspect 28: The method as described in aspect 24, wherein the configuration indicates that the number of SCI phases is one or two.

[0137] Aspect 29: The method as described in aspect 22, further comprising: in a first SCI transmission, providing an indication to the receiving UE as to whether the SCI is sent in one phase or in multiple phases.

[0138] Aspect 30: The method as described in aspect 29, wherein based on the format of the first SCI or the value of one or more fields in the first SCI, the indication is implicit in the first SCI transmission.

[0139] Aspect 31: The method as described in aspect 30, wherein the implicit indication is based on the destination address.

[0140] Aspect 32: The method as described in aspect 29, wherein the first SCI includes an explicit indication of whether the SCI is sent in one phase or in multiple phases.

[0141] Aspect 33: The method as described in aspect 23, wherein the determination is based on downlink control information (DCI) transmitted from a network entity to a transmitting UE.

[0142] Aspect 34: The method as described in aspect 23, wherein a radio network entity notifies a receiving UE about the SCI phase determination.

[0143] Aspect 35: The method as described in aspect 22, wherein the determination is applied to sidelink communication per link, per resource pool, or per specific subset of a resource pool.

[0144] Aspect 36: The method as described in aspect 22, wherein the determination is to send the SCI in a single phase.

[0145] Aspect 37: The method as described in aspect 36, wherein the single-phase SCI includes information that would be carried in at least a second phase if the SCI is sent in multiple phases.

[0146] Aspect 38: The method as described in aspect 36, wherein the single-phase SCI includes one or more of the following fields: a new data indicator (NDI), a hybrid automatic repeat request (HARQ) process identifier (ID), a source ID, a destination ID, or a channel state information (CSI) report trigger.

[0147] Aspect 39: The method as described in aspect 36, wherein information that would be carried in at least a second phase if the SCI is sent in multiple phases is conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling.

[0148] Aspect 40: The method as described in aspect 36, wherein information that would be carried in at least a second phase if the SCI is sent in multiple phases is derived from the information in the single-phase SCI.

[0149] Aspect 41: The method as described in aspect 36, wherein a default value of an assumption about information that would be carried in at least a second phase if the SCI is sent in multiple phases is derived from the information in the single-phase SCI.

[0150] Aspect 42: The method as described in aspect 22, wherein each SCI phase in one or more SCI phases involves sending the SCI in a single packet.

[0151] Aspect 43: A method for wireless communication by a network entity, comprising: determining whether a first UE is to send sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to a second UE in one phase or in multiple phases; and providing an indication to at least one of the first UE or the second UE as to whether the first UE is to send the SCI in one phase or in multiple phases.

[0152] Aspect 44: The method according to aspect 43, wherein the indication is provided via downlink control information (DCI).

[0153] Aspect 45: The method according to aspect 44, wherein the DCI includes at least one of the following: a transmission authorization for the first UE; or a reception authorization for the second UE.

[0154] Aspect 46: An apparatus for wireless communication by a transmitting user equipment (UE), comprising: means for determining whether to send sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to a receiving UE in one phase or in multiple phases; means for sending the SCI according to the determination; and means for sending the PSSCH according to the SCI.

[0155] Aspect 47: An apparatus for wireless communication by a receiving user equipment (UE), comprising: means for determining whether to receive sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission from a transmitting UE in one phase or in multiple phases; means for processing the SCI according to the determination; and means for decoding the PSSCH according to the SCI.

[0156] Aspect 48: An apparatus for wireless communication by a network entity, comprising: means for determining whether a first UE is to send sidelink control information (SCI) for decoding a physical sidelink shared channel (PSSCH) transmission to a second UE in one phase or in multiple phases, and means for providing an indication to at least one of the first UE or the second UE as to whether the first UE is to send the SCI in one phase or in multiple phases.

[0157] The methods disclosed herein include one or more steps or actions for implementing the method. Without departing from the scope of the claims, the method steps and / or actions may be interchanged 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 may be modified without departing from the scope of the claims.

[0158] As used herein, the phrase "at least one" in reference to a list of items means any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination having multiple of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c, or any other permutation of a, b, and c).

[0159] As used herein, the term "determine" encompasses a variety of actions. For example, "determine" can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, database, or another data structure), ascertaining, etc. Further, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. Still further, "determine" can include parsing, selecting, choosing, establishing, etc.

[0160] The foregoing description has been provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily 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 aspects shown herein but are to be accorded the full scope consistent with the language of the claims, where the elements are recited in the singular and are not intended to mean "one and only one" unless specifically so stated, but rather "one or more." The term "some," unless specifically stated otherwise, means one or more. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are known to those of ordinary skill in the art or will be known in the future are hereby expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is expressly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the phrase "step for."

[0161] The various operations of the above-described method can be performed by any suitable means capable of performing the corresponding functions. The means can include various hardware and / or software components and / or modules, including but not limited to circuitry, an application specific integrated circuit (ASIC), or a processor. Generally, where there are operations shown in the figures, those operations can have corresponding means-plus-function components. For example,Figure 7 , Figure 8 and / or Figure 9 The various operations shown in Figure 4 can be performed by the various processors shown in for UE 120a and / or BS110a.

[0162] The various illustrative logic blocks, modules, and circuits described in connection with the present disclosure can be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0163] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system can be implemented with a bus architecture. Depending on the particular use and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus can link together various circuits, including a processor, a machine-readable medium, and a bus interface. Among other things, the bus interface can be used to connect a network adapter to the processing system via the bus. The network adapter can be used to implement the signal processing functions of the PHY layer. In the case of the user terminal 120 (see Figure 1 ), a user interface (e.g., keyboard, display, mouse, joystick, etc.) can also be connected to the bus. The bus can also link together various other circuits, such as a timing source, peripherals, voltage regulators, power management circuits, etc., which are well known in the art and will not be described further herein. The processor can be implemented with one or more general purpose 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 best to implement the functions of the processing system in light of the particular use and overall design constraints imposed on the overall system.

[0164] If implemented in software, the functions can be stored on or transmitted through 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 shall be construed broadly to mean instructions, data, or any combination thereof. A computer-readable medium includes both a computer storage medium and a communication medium, and the communication medium includes any medium that facilitates the transfer 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. The computer-readable storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integrated into the processor. As an example, a machine-readable medium may include a transmission line, a carrier modulated with data, and / or a computer-readable storage medium storing instructions separate from a wireless node, all of which can be accessed by the processor via a bus interface. Alternatively or additionally, a machine-readable medium or any part thereof may be integrated into the processor, such as may be the case with a cache and / or a general register file. Examples of a machine-readable storage medium 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 disk drives, or any other suitable storage medium, or any combination thereof. A machine-readable medium may be included in a computer program product.

[0165] Software modules may include a single instruction or multiple instructions and may be distributed over several different code segments, different programs, and multiple storage media. A computer-readable medium may include several software modules. Software modules include instructions that, when executed by a device such as a processor, cause the processing system to perform various functions. Software modules may include a sending module and a receiving module. Each software module may reside in a single storage device or be distributed over multiple storage devices. As an example, when a triggering 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 the cache to improve access speed. Then one or more cache lines may be loaded into the general register file for the processor to execute. When referring to the functions of a software module below, it should be understood that these functions are implemented by the processor when executing the instructions from the software module.

[0166] In addition, any connection is properly defined as a 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, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. The magnetic disks and optical disks used herein include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and discs, where magnetic disks typically reproduce data magnetically, while optical discs reproduce data optically with a laser. Thus, in some aspects, a computer-readable medium may include a non-transitory computer-readable medium (e.g., a tangible medium). In addition, for other aspects, a computer-readable medium may include a transitory computer-readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

[0167] 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 that are executable by one or more processors to perform the operations described herein. For example, instructions for performing the operations described and illustrated in Figures 7 - 9 are shown.

[0168] In addition, it should be understood that, if applicable, modules and / or other suitable components for performing the methods and techniques described herein may be downloaded and / or otherwise obtained by a user terminal and / or a base station. 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 via a storage component (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk, etc.) such that the user terminal and / or the base station may obtain the various methods when the storage component is coupled or provided to the device. In addition, any other suitable technique for providing the methods and techniques described herein to a device may be utilized.

[0169] It should be understood that the claims are not limited to the exact configurations and components described above. Various modifications, changes, and variations may be made to the arrangement, operation, and details of the above methods and apparatuses without departing from the scope of the claims.

Claims

1. A method for wireless communication by a sending user equipment (UE), comprising: in a first stage of a plurality of stages, receiving a configuration indicating an indication to send sidelink control information (SCI) to a receiving UE; and transmitting the SCI in the first stage according to the received indication, wherein the SCI in the first stage indicates the size of a physical sidelink shared channel (PSSCH) resource allocation, wherein the size of the PSSCH resource allocation indicates the presence or absence of at least a second stage of the plurality of stages, and wherein, if SCI is transmitted in the plurality of stages, information carried in the at least second stage of the plurality of stages is included in the first stage.

2. The method according to claim 1, wherein, the configuration indicates a configuration of one or more stages of the plurality of stages for sending the SCI.

3. The method according to claim 2, wherein, the configuration is conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling.

4. The method according to claim 3, wherein, the configuration is received from a network entity.

5. The method according to claim 3, wherein, the configuration is conveyed via sidelink RRC.

6. The method according to claim 3, wherein, the configuration indicates that the number of SCI stages is two.

7. The method according to claim 2, wherein, the configuration expires within a set time period or until a further configuration is received.

8. The method according to claim 1, wherein, the configuration with the indication is received via downlink control information (DCI) transmitted from a radio network entity to the sending UE.

9. The method according to claim 1, wherein, the indication is applied to sidelink communication per link, per resource pool, or a specific subset of each resource pool.

10. The method according to claim 1, wherein, the first stage SCI includes fields of one or more of the following: a new data indicator (NDI), a hybrid automatic repeat request (HARQ) process identifier (ID), a source ID, a destination ID, or a channel state information (CSI) report trigger.

11. The method according to claim 1, wherein, if the SCI is transmitted in the plurality of stages, the information to be carried in the at least second stage is conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling.

12. The method according to claim 1, wherein, the information to be carried in the at least second stage if the SCI is transmitted in the plurality of stages is derived from the information in the first stage.

13. The method according to claim 1, wherein, a default value of an assumption about the information to be carried in the at least second stage if the SCI is transmitted in the plurality of stages is derived from the information in the first stage.

14. The method according to claim 1, wherein, the first stage involves sending the SCI in a single packet.

15. A method for wireless communication by a receiving user equipment (UE), comprising: in a first stage of a plurality of stages, receiving a configuration indicating a side link control information (SCI) from a transmitting UE; receiving the SCI in the first stage according to the received indication, wherein the SCI in the first stage indicates the size of a physical side link shared channel (PSSCH) resource allocation, wherein the size of the PSSCH resource allocation indicates the presence or absence of at least a second stage of the plurality of stages, and wherein if the SCI is transmitted in the plurality of stages, the information carried in the at least second stage of the plurality of stages is included in the first stage; and processing the SCI.

16. The method according to claim 15, wherein, the configuration indicates a configuration of one or more stages of the plurality of stages for transmitting the SCI.

17. The method according to claim 16, wherein, the configuration is conveyed via radio resource control (RRC) or medium access control (MAC) control element (CE) signaling.

18. The method according to claim 16, wherein, the configuration expires within a set time period or until a further configuration is received.

19. The method according to claim 17, wherein, the configuration indicates that the number of SCI stages is two.

20. The method according to claim 15, wherein, the indication is applied to sidelink communication per link, per resource pool, or a specific subset of per resource pool.

21. The method according to claim 15, wherein, the first stage involves transmitting the SCI in a single packet.

22. A method for wireless communication by a network entity, comprising: determining a configuration of a first user equipment (UE) to send side link control information (SCI) to a second UE in a first stage of a plurality of stages; and providing the configuration to the first UE and the second UE, the configuration having an indication that the first UE will send the SCI in the first stage of the plurality of stages, wherein the SCI in the first stage indicates the size of a physical side link shared channel (PSSCH) resource allocation, and wherein the size of the PSSCH resource allocation indicates the presence or absence of at least a second stage of the plurality of stages.

23. The method according to claim 22, wherein, the configuration having the indication is provided via downlink control information (DCI).

24. The method according to claim 23, wherein, the DCI includes at least one of the following: a transmission grant for the first UE; or a reception grant for the second UE.

25. An apparatus for wireless communication by a network entity, comprising: means for determining a configuration of a first user equipment (UE) to send side link control information (SCI) to a second UE in a first stage of a plurality of stages, and means for providing the configuration to the first UE and the second UE, the configuration having an indication that the first UE will send the SCI in the first stage of the plurality of stages, Wherein the SCI in the first phase indicates the size of the physical side link shared channel (PSSCH) resource allocation, and wherein the size of the PSSCH resource allocation indicates the presence or absence of at least a second phase among the plurality of phases.

26. An apparatus for wireless communication at a transmitting user equipment (UE), comprising: a memory; and one or more processors coupled to the memory, the one or more processors configured to cause the UE to perform the method according to any one of claims 1-21.

27. An apparatus for wireless communication at a transmitting user equipment (UE) for performing the steps of the method according to any one of claims 1-21.

28. An apparatus for wireless communication at a network entity, comprising: a memory; and one or more processors coupled to the memory, the one or more processors configured to cause the network entity to perform the method according to any one of claims 22-24.

29. A non-transitory computer-readable medium storing one or more instructions, wherein the one or more instructions, when executed by one or more processors, cause the one or more processors to perform the method according to any one of claims 1-21 and 22-24.

30. A computer program product comprising computer instructions that, when executed by a processor, perform the method according to any one of claims 1-21 and 22-24.

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