Wireless communication method, device and computer readable medium

Abstract

Various aspects relate to resource selection of a first device in a wireless communication network. A second device may reserve resources for a first transmission and a retransmission to at least one third device via a direct link. If a signal strength received from the second device is greater than a threshold, the first device may detect feedback from the at least one third device to determine whether there will be a retransmission. If there will be no retransmission, the first device may add at least one resource that overlaps with at least one of the resources previously reserved for the retransmission to a candidate set. If the signal strength is less than a threshold, the first device may add at least one resource that overlaps with at least one of the resources previously reserved for the retransmission to the candidate set of resources without detecting feedback.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to and the benefit of co-pending non-provisional application No. 17 / 210,246 filed in the U.S. Patent and Trademark Office on March 23, 2021, and provisional application No. 62 / 994,154 filed in the U.S. Patent and Trademark Office on March 24, 2020, which provisional applications are assigned to the assignee of this application and are hereby expressly incorporated herein by reference as if fully set forth herein in their entirety for all applicable purposes. Technical Field

[0003] The techniques discussed below relate generally to wireless communications and, more particularly, to resource selection with selective detection including feedback. Background Art

[0004] In many existing wireless communication systems, cellular networks are implemented by enabling wireless communication devices to communicate with each other through signaling with nearby base stations or cells. When wireless communication devices move across a service area, handover occurs so that each wireless communication device maintains communication with each other via its respective cell.

[0005] Another approach to wireless communication systems is a device-to-device (D2D) network, in which wireless communication devices can send signals directly to each other, rather than through an intermediate base station or cell. A D2D communication network can utilize direct signaling (e.g., sidelink signaling) to facilitate direct communication between wireless communication devices through a proximity service (ProSe) PC5 interface. In some D2D configurations, wireless communication devices can also communicate in a cellular system, typically under the control of a base station. Therefore, wireless communication devices can be configured for uplink and downlink signaling via a base station, and also for sidelink signaling directly between wireless communication devices without passing through a base station.

[0006] An example of a sidelink wireless communication system is a vehicle-to-everything (V2X) communication system. V2X communication involves the exchange of information not only between vehicles themselves, but also between vehicles and external systems, such as street lights, buildings, pedestrians, and wireless communication networks. V2X systems enable vehicles to obtain information related to weather, nearby accidents, road conditions, activities of nearby vehicles and pedestrians, objects near the vehicle, and other relevant information that can be used to improve the vehicle driving experience, increase vehicle safety, and support autonomous vehicles. Summary of the invention

[0007] An overview of one or more aspects of the present disclosure is given below to provide a basic understanding of these aspects. This overview is not an extensive review of all expected features of the present disclosure, and is neither intended to identify key or important elements of all aspects of the present disclosure, nor is it intended to describe the scope of any or all aspects of the present disclosure. Its sole purpose is to present some concepts of one or more aspects of the present disclosure in some form as a preface to a more detailed description presented later.

[0008] In some examples, a method for wireless communication at a first wireless communication device is disclosed. The method may include receiving a signal from a second wireless communication device and measuring a signal strength of the signal. The method may also include receiving control information indicating that the second wireless communication device has reserved a first resource of a plurality of resources for a first transmission to at least one third wireless communication device, and has reserved at least one second resource of a plurality of resources for at least one retransmission to at least one third wireless communication device. In addition, the method may include decoding feedback associated with the first transmission when the signal strength is greater than a threshold, or avoiding detecting feedback when the signal strength is less than a threshold.

[0009] In some examples, a first wireless communication device may include a transceiver, a memory, and a processor communicatively coupled to the transceiver and the memory. The processor and the memory may be configured to receive a signal from a second wireless communication device via the transceiver and measure the signal strength of the signal. The processor and the memory may also be configured to receive control information indicating that the second wireless communication device has reserved a first resource from a plurality of resources for a first transmission to at least one third wireless communication device, and has reserved at least one second resource from a plurality of resources for at least one retransmission to at least one third wireless communication device. In addition, the processor and the memory may be configured to decode feedback associated with the first transmission when the signal strength is greater than a threshold, or to avoid detecting feedback when the signal strength is less than a threshold.

[0010] In some examples, a first wireless communication device may include a component for receiving a signal from a second wireless communication device and a component for measuring a signal strength of the signal. The component for receiving may be configured to receive control information indicating that the second wireless communication device has reserved a first resource of a plurality of resources for a first transmission to at least one third wireless communication device and has reserved at least one second resource of a plurality of resources for at least one retransmission to at least one third wireless communication device. The apparatus may also include a component for decoding feedback associated with the first transmission when the signal strength is greater than a threshold or avoiding detecting feedback when the signal strength is less than a threshold.

[0011] In some examples, an article of manufacture for use with a first wireless communication device includes a non-transitory computer-readable medium having stored therein instructions executable by one or more processors of the first wireless communication device to receive a signal from a second wireless communication device and measure the signal strength of the signal. The computer-readable medium may also store therein instructions executable by one or more processors of the first wireless communication device to receive control information instructing the second wireless communication device to reserve a first resource of a plurality of resources for a first transmission to at least one third wireless communication device, and to reserve at least one second resource of the plurality of resources for a retransmission to at least one third wireless communication device. In addition, the computer-readable medium may store therein instructions executable by one or more processors of the first wireless communication device to decode feedback associated with the first transmission when the signal strength is greater than a threshold, or to avoid detecting feedback when the signal strength is less than a threshold.

[0012] By reading the detailed description below, these and other aspects of the present disclosure will become more comprehensive. By reading the following description of the specific example aspects of the present disclosure in conjunction with the accompanying drawings, other aspects, features and examples of the present disclosure will become apparent to those of ordinary skill in the art. Although the features of the present disclosure can be discussed with respect to certain examples and drawings below, all examples of the present disclosure can include one or more advantageous features discussed herein. In other words, although one or more examples can be discussed as having certain advantageous features, one or more such features can also be used according to the various examples of the present disclosure discussed herein. In a similar manner, although the example aspects can be discussed below as device, system or method examples, it should be understood that these example aspects can be implemented in various devices, systems and methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram illustrating an example of a wireless radio access network in accordance with some aspects.

[0014] Figure 2 is a diagram illustrating organization of wireless resources in an air interface using orthogonal frequency division multiplexing (OFDM) in accordance with some aspects.

[0015] Figure 3 is a diagram illustrating an example of a wireless communication network employing sidelink communications in accordance with some aspects.

[0016] Figure 4A is a conceptual diagram illustrating an example of a side link slot structure according to some aspects.

[0017] Figure 4B is a conceptual diagram illustrating another example of a side link slot structure according to some aspects.

[0018] Figure 5 is a conceptual diagram illustrating an example of a sidelink slot structure with feedback resources in accordance with some aspects.

[0019] Figure 6 is a diagram illustrating an example of resource allocation in accordance with some aspects.

[0020] Figure 7 is a diagram illustrating examples of groups that may be formed in a direct wireless communication system according to some aspects.

[0021] Figure 8 is a signaling diagram illustrating an example of signaling for a first type of feedback based retransmission in a direct wireless communication system according to some aspects.

[0022] Fig. 9 is a signaling diagram illustrating an example of signaling for a second type of feedback based retransmission in a direct wireless communication system according to some aspects.

[0023] Fig.10 is a flow chart of an example method for a user equipment (UE) to reserve resources in a direct wireless communication system according to some aspects.

[0024] Fig.11 is a block diagram illustrating an example of a hardware implementation for a wireless communication device employing a processing system in accordance with some aspects.

[0025] Fig.12 is a flow chart of an example method for a wireless communication device in accordance with some aspects.

[0026] Fig.13 is a flow chart of an example method for a wireless communication device to reserve resources in a direct wireless communication system in accordance with some aspects.

[0027] Fig.14 is a flow chart of an example method for a wireless communication device to reserve resources without detecting feedback within a direct wireless communication system in accordance with some aspects.

[0028] Fig.15 is a flow chart of an example method for reserving resources by a wireless communication device according to some aspects, the method including detecting feedback within a direct wireless communication system.

[0029] Fig.16 is a flow chart of an example method for a wireless communication device to send a packet on selected resources in accordance with some aspects.

[0030] Fig.17 is a flow chart of an example method by which a wireless communication device determines whether to send a retransmission in accordance with some aspects.

[0031] Fig.18is a flow chart of another example method by which a wireless communication device determines whether to send a retransmission in accordance with some aspects. DETAILED DESCRIPTION

[0032] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some cases, in order to avoid confusion with these concepts, well-known structures and components are shown in block diagram form.

[0033] Although aspects and examples are described in this application by the description of some examples, it will be understood by those skilled in the art that additional implementations and use cases may occur in many different arrangements and scenarios. The innovation described herein can be implemented across many different platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, aspects and / or uses can be implemented by integrated chip examples and other devices based on non-module components (e.g., end-user devices, vehicles, communication devices, computing devices, industrial devices, retail / purchasing devices, medical devices, artificial intelligence enabling (AI enabling) devices, etc.). Although some examples may or may not be specifically for use cases or applications, various applicability of the described innovations may occur. The scope of implementation can range from chip-level or modular components to non-modular, non-chip-level implementations, and further to aggregation, distribution, or original equipment manufacturer (OEM) devices or systems incorporating one or more aspects of the described innovations. In some actual settings, the device incorporating the described aspects and features may also have to include additional components and features for implementing and practicing the claimed and described examples. For example, the transmission and reception of wireless signals must include multiple components for analog and digital purposes (e.g., hardware components include antennas, radio frequency (RF) chains, power amplifiers, modulators, buffers, processors, interleavers, adders / summers, etc.) It is intended that the innovations described herein can be practiced in devices of various sizes, shapes, and configurations, chip-level components, systems, distributed arrangements, end-user devices, etc.

[0034] Various aspects of the present disclosure relate to mechanisms for resource reservation by a first wireless communication device in a direct (e.g., sidelink) wireless communication network, such as a vehicle-to-everything (V2X) network. In such a network, a second wireless communication device may reserve resources for a first transmission and at least one retransmission over a direct link to at least one third wireless communication device. The first wireless communication device may measure the strength of a signal received from the second wireless communication device.

[0035] In some examples, if the signal strength is greater than a threshold, the first wireless communication device may monitor feedback from at least one third wireless communication device to determine whether the second wireless communication device will retransmit. If there will be no retransmission, the first wireless communication device may use at least one resource that overlaps (i.e., at least partially overlaps) with a resource previously reserved by the second wireless communication device for at least one retransmission. For example, the first wireless communication device may include one or more resources in the candidate set that overlap with resources that the second wireless communication device will not use due to the absence of retransmissions. The first wireless communication device may then select (e.g., randomly select) one or more resources from the candidate set to send the packet.

[0036] In some examples, if the signal strength is less than a threshold, the first wireless communication device may use at least one resource that overlaps with a resource previously reserved by the second wireless communication device for at least one retransmission without first detecting (e.g., monitoring) feedback. For example, the first wireless communication device may include one or more resources in the candidate set that overlap with a resource reserved by the second wireless communication device for at least one retransmission. The first wireless communication device may then select (e.g., randomly select) one or more resources from the candidate set to send the packet.

[0037] The various concepts presented throughout this disclosure may be implemented across a variety of telecommunication systems, network architectures and communication standards. Figure 1 , as a non-limiting illustrative example, a schematic diagram of a radio access network (RAN) 100 is provided. The RAN 100 may implement any suitable one or more wireless communication technologies to provide radio access. As an example, the RAN 100 may operate in accordance with the Third Generation Partnership Project (3GPP) New Radio (NR) specifications (commonly referred to as 5G). As another example, the RAN 100 may operate under a mix of 5G NR and Evolved Universal Terrestrial Radio Access Network (eUTRAN) standards (commonly referred to as LTE). 3GPP refers to such a hybrid RAN as the Next Generation RAN, or NG-RAN. Of course, many other examples may be utilized within the scope of the present disclosure.

[0038] The geographical area covered by the radio access network 100 may be divided into a plurality of cellular areas (cells) which may be uniquely identified by a user equipment (UE) based on an identity broadcast over the geographical area from an access point or base station. Figure 1Cells 102, 104, 106, and cell 108 are shown, each of which may include one or more sectors (not shown). A sector is a sub-region of a cell. All sectors within a cell are served by the same base station. A radio link within a sector may be identified by a single logical identifier belonging to the sector. In a cell divided into sectors, multiple sectors within a cell may be formed by antenna groups, each antenna being responsible for communicating with a UE in a portion of the cell.

[0039] Typically, a corresponding base station (BS) serves each cell. In a broad sense, a base station is a network element in a radio access network, responsible for radio transmission and reception to or from a UE in one or more cells. Those skilled in the art may also refer to a BS as a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a node B (NB), an eNode B (eNB), a gNode B (gNB), a transmission and reception point (TRP), or some other suitable term. In some examples, a base station may include two or more TRPs, which may be collocated or non-collocated. Each TRP may communicate on the same or different carrier frequencies in the same or different frequency bands. In an example where RAN 100 operates according to LTE and 5G NR standards, one of the base stations may be an LTE base station, and the other base station may be a 5G NR base station.

[0040] Various base station arrangements can be used. Figure 1 , two base stations 110 and 112 are shown in cells 102 and 104; and a third base station 114 is shown as controlling a remote radio head (RRH) 116 in cell 106. That is, the base station may have an integrated antenna, or may be connected to an antenna or RRH by a feeder cable. In the example shown, cells 102, 104, and 106 may be referred to as macro cells because base stations 110, 112, and 114 support cells with large sizes. In addition, a base station 118 is shown in cell 108, which may overlap with one or more macro cells. In this example, cell 108 may be referred to as a small cell (e.g., a micro cell, a pico cell, a femto cell, a home base station, a home node B, a home e Node B, etc.) because base station 118 supports a cell with a relatively small size. The cell size may be determined based on system design and component constraints.

[0041] It should be understood that the radio access network 100 may include any number of wireless base stations and cells. In addition, relay nodes may be deployed to extend the size or coverage area of ​​a given cell. The base stations 110, 112, 114, 118 provide radio access points to the core network for any number of mobile devices.

[0042] Figure 1 Also included is an unmanned aerial vehicle (UAV) 120, which may be a drone or a quadcopter. UAV 120 may be configured to function as a base station, or more specifically as a mobile base station. That is, in some examples, the cell is not necessarily stationary, and the geographic area of ​​the cell may move depending on the location of a mobile base station such as UAV 120.

[0043] Typically, a base station may include a backhaul interface for communicating with a backhaul portion of the network (not shown). The backhaul may provide a link between the base station and a core network (not shown), and in some examples, the backhaul may provide interconnections between the various base stations. The core network may be part of a wireless communication system and may be independent of the radio access technology used in the radio access network. Various types of backhaul interfaces may be employed, such as a direct physical connection using any suitable transport network, a virtual network, and the like.

[0044] RAN 100 is shown to support wireless communications for multiple mobile devices. In the standards and specifications promulgated by the Third Generation Partnership Project (3GPP), mobile devices are generally referred to as user equipment (UE), but those skilled in the art may also refer to them as mobile stations (MS), subscriber stations, mobile units, subscriber units, wireless units, remote units, mobile devices, wireless devices, wireless communication devices, remote devices, mobile subscriber stations, access terminals (AT), mobile terminals, wireless terminals, remote terminals, handsets, terminals, user agents, mobile clients, clients, or some other suitable terms. UE may be a device that provides network service access to a user.

[0045] In this document, a "mobile" device does not necessarily need to have the ability to move, and can be stationary. The term mobile device or mobile device refers to various devices and technologies. For example, some non-limiting examples of mobile devices include mobile phones, cellular (cellular) phones, smart phones, session initiation protocol (SIP) phones, laptops, personal computers (PCs), notebooks, netbooks, smart books, tablet computers, personal digital assistants (PDAs) and various embedded systems, such as corresponding to the "Internet of Things" (IoT). Mobile devices can also be cars or other vehicles, remote sensors or actuators, robots or robotic devices, satellite radios, global positioning system (GPS) devices, object tracking devices, unmanned aircraft, multi-axis helicopters, quadcopters, remote control devices, consumers and / or wearable devices, such as glasses, wearable cameras, virtual reality devices, smart watches, health or fitness trackers, digital audio players (e.g., MP3 players), cameras, game consoles, etc. Mobile devices can also be digital homes or smart home devices, such as home audio, video and / or multimedia devices, electrical appliances, vending machines, smart lighting, home security systems, smart meters, etc. The mobile device may also be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device that controls power (e.g., smart grid), lighting, water, etc., an industrial automation and enterprise device, a logistics controller, an agricultural device, etc. In addition, the mobile device may provide connected medical or telemedicine support, i.e., remote health care. Telehealth devices may include remote health monitoring devices and remote health management devices, whose communications may be given priority treatment or priority access over other types of information, for example, in terms of priority access to critical service data transmission and / or associated QoS for critical service data transmission.

[0046] Within the RAN 100, the cells may include UEs that may communicate with one or more sectors of each cell. For example, UEs 122 and 124 may communicate with base station 110; UEs 126 and 128 may communicate with base station 112; UEs 130 and 132 may communicate with base station 114 via RRH 116; UE 134 may communicate with base station 118; and UE 136 may communicate with a mobile base station (e.g., UAV 120). Here, each base station 110, 112, 114, 118, and 120 may be configured to provide an access point to a core network (not shown) for all UEs in the corresponding cell. In some examples, UAV 120 (e.g., a quadcopter) may be a mobile network node and may be configured to function as a UE. For example, UAV 120 may operate within cell 102 by communicating with base station 110.

[0047] Wireless communication between RAN 100 and UE (e.g., UE 122 or 124) can be described as utilizing an air interface. Transmissions from a base station (e.g., base station 110) to one or more UEs (e.g., UE 122 and 124) over an air interface can be referred to as downlink (DL) transmissions. According to certain aspects of the present disclosure, the term downlink may refer to point-to-multipoint transmissions initiated at a scheduling entity (further described below; e.g., base station 110). Another way to describe the scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE 122) to a base station (e.g., base station 110) may be referred to as uplink (UL) transmissions. According to other aspects of the present disclosure, the term uplink may refer to point-to-point transmissions initiated at a scheduled entity (further described below; e.g., UE 122).

[0048] For example, DL transmission may include unicast or broadcast transmission of control information and / or service information (e.g., user data service) from a base station (e.g., base station 110) to one or more UEs (e.g., UEs 122 and 124), and UL transmission may include transmission of control information and / or service information from a UE (e.g., UE 122). In addition, uplink and / or downlink control information and / or service information may be divided into frames, subframes, time slots and / or symbols in time. As used herein, a symbol may refer to a time unit, which carries one resource element (RE) per subcarrier in an orthogonal frequency division multiplexing (OFDM) waveform. A time slot may carry 7 or 14 OFDM symbols. A subframe may refer to a duration of 1 millisecond. Multiple subframes or time slots may be grouped together to form a single frame or radio frame. In the present disclosure, a frame may refer to a predetermined duration (e.g., 10 milliseconds (ms)) for wireless transmission, wherein each frame includes, for example, 10 subframes, each subframe being 1 ms. Of course, these definitions are not required, and any suitable scheme for organizing the waveform may be utilized, and the various time divisions of the waveform may have any suitable duration.

[0049] In some examples, access to the air interface may be scheduled, where a scheduling entity (e.g., a base station) allocates resources (e.g., time-frequency resources) for communications between some or all devices and apparatuses within its service area or cell. In the present disclosure, as discussed further below, a scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more scheduled entities. That is, for scheduled communications, a UE or scheduled entity utilizes resources allocated by the scheduling entity.

[0050] The base station is not the only entity that can act as a scheduling entity. That is, in some examples, the UE can act as a scheduling entity to schedule resources for one or more scheduled entities (e.g., one or more other UEs). For example, two or more UEs (e.g., UEs 138, 140, and 142) can use side link signals 137 to communicate with each other without relaying the communication through a base station. In some examples, UEs 138, 140, and 142 can each be used as a scheduling entity or a transmitting side link device and / or a scheduled entity or a receiving side link device to schedule resources and transmit side link signals 137 between them without relying on scheduling or control information from the base station. In other examples, two or more UEs (e.g., UEs 126 and 128) within the coverage area of ​​a base station (e.g., base station 112) can also transmit side link signals 127 on a direct link (side link) without transmitting the communication through base station 112. In this example, base station 112 can allocate resources to UEs 126 and 128 for side link communication. In either case, such sidelink signaling 127 and 137 may be implemented in a peer-to-peer (P2P) network, a device-to-device (D2D) network, a vehicle-to-vehicle (V2V) network, a vehicle-to-everything (V2X) network, a mesh network, or other suitable direct link network.

[0051] In some examples, a D2D relay framework may be included within the cellular network to facilitate relaying of communications to / from base station 112 via a D2D link (e.g., side link 127 or 137). For example, one or more UEs (e.g., UE 128) within the coverage area of ​​base station 112 may operate as relay UEs to extend the coverage of base station 112, improve transmission reliability to one or more UEs (e.g., UE 126), and / or allow the base station to recover from a failed UE link due to, for example, congestion or fading.

[0052] The two main technologies that V2X networks can use include dedicated short-range communications (DSRC) based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11p standard and cellular V2X based on LTE and / or 5G (new radio) standards. Various aspects of the present disclosure may be directed to new radio (NR) cellular V2X networks, which for simplicity are referred to herein as V2X networks. However, it should be understood that the concepts disclosed herein may not be limited to a specific V2X standard, or may be directed to sidelink networks other than V2X networks.

[0053] In order to obtain a low block error rate (BLER) for transmission over the air interface while still achieving very high data rates, channel coding can be used. That is, wireless communications can usually utilize suitable error-correcting block codes. In a typical block code, an information message or sequence is divided into code blocks (CBs), and then an encoder (e.g., a codec CODEC) at the transmitting device mathematically adds redundancy to the information message. The use of this redundancy in the encoded information message can improve the reliability of the message, making it possible to correct any bit errors that may occur due to noise.

[0054] Data encoding can be implemented in a variety of ways. In early 5G NR specifications, user data is encoded using quasi-cyclic low-density parity check (LDPC) with two different basis patterns: one basis pattern is used for large code blocks and / or high code rates, and the other basis pattern is used for other cases. Control information and the physical broadcast channel (PBCH) are encoded using polar coding based on nested sequences. For these channels, puncturing, shortening, and repetition are used for rate matching.

[0055] Aspects of the present disclosure may be implemented using any suitable channel codes. Various implementations of base stations and UEs may include suitable hardware and capabilities (eg, encoders, decoders, and / or codecs (CODECs)) to utilize one or more of these channel codes for wireless communications.

[0056] In the RAN 100, the ability of a UE to communicate independently of its location while moving is called mobility. Various physical channels between the UE and the RAN are usually established, maintained, and released under the control of an access and mobility management function (AMF). In some scenarios, the AMF may include a security context management function (SCMF) and a security anchor function (SEAF) that perform authentication. The SCMF may manage the security context of both the control plane and the user plane functions in whole or in part.

[0057] In some examples, the RAN 100 may implement mobility and handover (i.e., transferring a UE's connection from one radio channel to another). For example, during a call with a scheduling entity, or at any other time, the UE may monitor various parameters of the signal from its serving cell and various parameters of neighboring cells. Based on the quality of these parameters, the UE may maintain communication with one or more neighboring cells. During this period, if the UE moves from one cell to another, or if the signal quality from a neighboring cell exceeds the signal quality from the serving cell for a given amount of time, the UE may perform a handover or handover from the serving cell to a neighboring (target) cell. For example, a UE 124 may move from a geographic area corresponding to its serving cell 102 to a geographic area corresponding to a neighboring cell 106. When the signal strength or quality from a neighboring cell 106 exceeds the signal strength or quality of its serving cell 102 for a given amount of time, the UE 124 may send a report message to its serving base station 110 indicating this situation. In response, the UE 124 may receive a handover command, and the UE may perform a handover to the cell 106.

[0058] In various implementations, the air interface in the RAN 100 may utilize licensed spectrum, unlicensed spectrum, or shared spectrum. Licensed spectrum provides exclusive use of a portion of spectrum, typically through the purchase of a license by a mobile network operator from a government regulator. Unlicensed spectrum provides shared use of a portion of spectrum without the need for a government-granted license. While some technical rules generally still need to be followed to access unlicensed spectrum, generally any operator or device can gain access. Shared spectrum may be between licensed and unlicensed spectrum, where technical rules or restrictions may be required to access the spectrum, but the spectrum may still be shared by multiple operators and / or multiple RATs. For example, a license holder of a portion of licensed spectrum may provide licensed shared access (LSA) to share the spectrum with other parties, for example, to obtain access under appropriate conditions determined by the license holder.

[0059] The air interface in the RAN 100 may utilize one or more multiplexing and multiple access algorithms to enable simultaneous communication of various devices. For example, the 5G NR specification provides multiple access for UL or reverse link transmissions from UEs 122 and 124 to base station 110, and utilizes orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) to multiplex DL or forward link transmissions from base station 110 to UEs 122 and 124. In addition, for UL transmissions, the 5G NR specification provides support for discrete Fourier transform-spread spectrum-OFDM (DFT-s-OFDM) with CP (also known as single carrier FDMA (SC-FDMA)). However, within the scope of the present disclosure, multiplexing and multiple access are not limited to the above schemes, and may be provided using time division multiple access (TDMA), code division multiple access (CDMA), frequency division multiple access (FDMA), sparse code multiple access (SCMA), resource extension multiple access (RSMA), or other suitable multiple access schemes. In addition, multiplexed DL transmissions from base station 110 to UEs 122 and 124 may be provided using time division multiplexing (TDM), code division multiplexing (CDM), frequency division multiplexing (FDM), orthogonal frequency division multiplexing (OFDM), sparse code multiplexing (SCM), or other suitable multiplexing schemes.

[0060] In addition, the air interface in the RAN 100 can utilize one or more duplex algorithms. Duplex refers to a point-to-point communication link in which two endpoints can communicate with each other in both directions. Full-duplex means that two endpoints can communicate with each other at the same time. Half-duplex means that only one endpoint can send information to the other endpoint at a time. Wireless links using time division duplex (TDD) often implement half-duplex simulation. In TDD, transmissions in different directions on a given channel are separated from each other using time division multiplexing. That is, sometimes the channel is dedicated to transmission in one direction, and at other times the channel is dedicated to transmission in another direction, where the direction can change very quickly, such as several times per time slot. In wireless links, full-duplex channels generally rely on physical isolation of transmitters and receivers, and suitable interference cancellation techniques. Frequency division duplex (FDD) or space division duplex (SDD) is usually used to implement full-duplex simulation of wireless links. In FDD, transmissions in different directions can operate on different carrier frequencies (e.g., in paired spectrum). In SDD, transmissions in different directions on a given channel are separated from each other using space division multiplexing (SDM). In other examples, full-duplex communication can be implemented in an unpaired spectrum (e.g., in a single carrier bandwidth), where transmissions in different directions occur in different sub-bands of the carrier bandwidth. This type of full-duplex communication may be referred to herein as sub-band full-duplex (SBFD), also known as flexible duplex.

[0061] Reference Figure 2Various aspects of the present disclosure are described with reference to the OFDM waveforms schematically shown in FIG. It will be appreciated by those skilled in the art that various aspects of the present disclosure may be applied to SC-FDMA waveforms in substantially the same manner as described below. That is, although some examples of the present disclosure may focus on OFDM links for clarity, it will be appreciated that the same principles may also be applied to SC-FDMA waveforms.

[0062] Reference now Figure 2 , shows an expanded view of an example frame 202 showing an OFDM resource grid. However, as will be readily appreciated by those skilled in the art, the physical layer (PHY layer) transmission structure for any particular application may differ from the examples described herein depending on many factors. Here, time is in the horizontal direction, in units of OFDM symbols; frequency is in the vertical direction, in units of subcarriers of a carrier.

[0063] Resource grid 204 can be used to schematically represent the time-frequency resources of a given antenna port. That is, in a multiple input multiple output (MIMO) implementation with multiple available antenna ports, a corresponding multiple number of resource grids 204 can be used for communication. Resource grid 204 is divided into multiple resource elements (RE) 206. RE is 1 subcarrier × 1 symbol, is the smallest discrete part of the time-frequency grid, and contains a single complex value representing data from a physical channel or signal. Depending on the modulation used in a specific implementation, each RE can represent one or more information bits. In some examples, a block of REs can be referred to as a physical resource block (PRB) or more simply a resource block (RB) 208, which contains any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB can include 12 subcarriers, which is independent of the parameter set (numerology) used. In some examples, depending on the parameter set, an RB can include any suitable number of consecutive OFDM symbols in the time domain. In the present disclosure, it is assumed that a single RB such as RB 208 corresponds entirely to a single communication direction (sending or receiving for a given device).

[0064] A group of contiguous or discontinuous resource blocks may be referred to herein as a resource block group (RBG), a subband, or a bandwidth part (BWP). A group of subbands or BWPs may span the entire bandwidth. Scheduling of a UE or sidelink device (hereinafter collectively referred to as a UE) for downlink, uplink, or sidelink transmission typically includes scheduling one or more resource elements 206 within one or more subbands or bandwidth parts (BWPs). Therefore, the UE typically utilizes only a subset of the resource grid 204. In some examples, an RB may be the smallest resource unit that can be allocated to a UE. Therefore, the more RBs scheduled for the UE, the higher the modulation scheme selected for the air interface, and the higher the data rate of the UE. The RB may be scheduled by a base station (e.g., a gNB, eNB, etc.) or may be scheduled by the UE / sidelink device implementing the D2D sidelink communication.

[0065] In this illustration, RB 208 is shown as occupying less than the entire bandwidth of subframe 202, with some subcarriers shown above and below RB 208. In a given implementation, subframe 202 may have a bandwidth corresponding to any number of RBs in one or more RBs 208. Furthermore, in this illustration, RB 208 is shown as occupying less than the entire duration of subframe 202, although this is merely one possible example.

[0066] Each 1 ms subframe 202 may include one or more adjacent time slots. Figure 2 In the example shown, as an illustrative example, a subframe 202 includes four time slots 210. In some examples, a time slot can be defined according to a specified number of OFDM symbols with a given cyclic prefix (CP) length. For example, a time slot can include 7 or 12 OFDM symbols with a nominal CP. Additional examples may include micro-slots with shorter durations (e.g., one to three OFDM symbols), sometimes referred to as shortened transmission time intervals (TTIs). In some cases, these micro-slots or shortened transmission time intervals (TTIs) may occupy resources scheduled for ongoing time slot transmissions of the same or different UEs to send. Any number of resource blocks can be used within a subframe or time slot.

[0067] The enlarged view of one of the time slots 210 illustrates the time slot 210 including a control region 212 and a data region 214. In general, the control region 212 may carry control channels, and the data region 214 may carry data channels. Of course, a time slot may contain all DL, all UL, or at least one DL portion and at least one UL portion. Figure 2 The structure shown is merely an example, and different slot structures may be utilized and may include one or more of each of the control region and the data region.

[0068] although Figure 2Although not shown in the figure, each RE 206 within the RB 208 can be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other REs 206 within the RB 208 can also carry pilot or reference signals. These pilot or reference signals can be provided to the receiving device to perform channel estimation of the corresponding channel, which can achieve coherent demodulation / detection of the control and / or data channels within the RB 208.

[0069] In some examples, time slot 210 may be used for broadcast, multicast, groupcast, or unicast communications. For example, broadcast, multicast, or groupcast communications may refer to point-to-multipoint transmissions from one device (e.g., a base station, UE, or other similar device) to other devices. Here, broadcast communications are transmitted to all devices, while multicast or groupcast communications are transmitted to multiple intended recipient devices. Unicast communications may refer to point-to-point transmissions from one device to a single other device.

[0070] In an example of cellular communication on a cellular carrier via a Uu interface, for DL ​​transmission, a scheduling entity (e.g., a base station) may allocate one or more REs 206 (e.g., within a control region 212) to carry DL control information including one or more DL control channels (e.g., a physical downlink control channel (PDCCH)) to one or more scheduled entities (e.g., UEs). The PDCCH carries downlink control information (DCI), including, but not limited to, power control commands (e.g., one or more open-loop power control parameters and / or one or more closed-loop power control parameters), scheduling information, grants, and / or RE allocations for DL ​​and UL transmissions. The PDCCH may also carry hybrid automatic repeat request (HARQ) feedback transmissions, such as an acknowledgement (ACK) or a negative acknowledgement (NACK). HARQ is a technique known to those of ordinary skill in the art, in which the integrity of a packet transmission may be checked on the receiving side to ensure accuracy, for example, using any suitable integrity checking mechanism, such as a checksum or a cyclic redundancy check (CRC). If the integrity of the transmission is acknowledged, an ACK may be sent, and if it is not acknowledged, a NACK may be sent. In response to the NACK, the transmitting device may send a HARQ retransmission, which may enable pursuit combining, incremental redundancy, and the like.

[0071] The base station may also allocate one or more REs 206 (e.g., in the control region 212 or the data region 214) to carry other DL signals, such as a demodulation reference signal (DMRS); a phase tracking reference signal (PT-RS); a channel state information (CSI) reference signal (CSI-RS); and a synchronization signal block (SSB). The SSBs may be broadcast at regular intervals based on a period (e.g., 5, 10, 20, 20, 80, or 120 milliseconds). The SSBs include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast control channel (PBCH). The UE may utilize the PSS and SSS to achieve radio frame, subframe, time slot, and symbol synchronization in the time domain, identify the center of the channel (system) bandwidth in the frequency domain, and identify the physical cell identity (PCI) of the cell.

[0072] The PBCH in the SSB may also include a master information block (MIB), which includes various system information and parameters for decoding a system information block (SIB). The SIB may be, for example, system information type 1 (SIB1), which may include various additional system information. The MIB and SIB1 together provide minimum system information (SI) for initial access. Examples of system information transmitted in the MIB may include, but are not limited to, subcarrier spacing (e.g., default downlink parameter set), system frame number, configuration of a PDCCH control resource set (CORESET) (e.g., PDCCH CORESET0), cell barring indicator, cell reselection indicator, raster offset, and search space of SIB1. Examples of remaining minimum system information (RMSI) transmitted in SIB1 may include, but are not limited to, random access search space, paging search space, downlink configuration information, and uplink configuration information.

[0073] In an UL transmission, a scheduled entity (e.g., a UE) may utilize one or more REs 206 to carry UL control information (UCI) including one or more UL control channels, such as a physical uplink control channel (PUCCH), to a scheduling entity. UCI may include various packet types and categories, including pilots, reference signals, and information configured to implement or assist in decoding uplink data transmissions. Examples of uplink reference signals may include a sounding reference signal (SRS) and an uplink DMRS. In some examples, the UCI may include a scheduling request (SR), i.e., a request to a scheduling entity to schedule an uplink transmission. Here, in response to the SR sent on the UCI, the scheduling entity may send downlink control information (DCI), which may schedule resources for uplink packet transmissions. The UCI may also include HARQ feedback, channel state feedback (CSF), such as a CSI report, or any other suitable UCI.

[0074] In addition to control information, one or more REs 206 may be allocated for data traffic (e.g., within data region 214). Such data traffic may be carried on one or more traffic channels, such as, for DL ​​transmissions, on a physical downlink shared channel (PDSCH); or for UL transmissions, on a physical uplink shared channel (PUSCH). In some examples, one or more REs 206 within data region 214 may be configured to carry other signals, such as one or more SIBs and DMRS.

[0075] In an example of sidelink communication on a sidelink carrier via a PC5 interface, a control region 212 of a time slot 210 may include a physical sidelink control channel (PSCCH) including sidelink control information (SCI) sent by an initiating (transmitting) sidelink device (e.g., a Tx V2X device or other Tx UE) to a group of one or more other receiving sidelink devices (e.g., an RxV2X device or other Rx UE). A data region 214 of the time slot 210 may include a physical sidelink shared channel (PSSCH) including sidelink data traffic sent by the initiating (transmitting) sidelink device via the SCI in resources reserved on the sidelink carrier. Other information may be further transmitted on each RE 206 within the time slot 210. For example, HARQ feedback information may be sent from a receiving sidelink device to a transmitting sidelink device in a physical sidelink feedback channel (PSFCH) within the time slot 210. Additionally, one or more reference signals may be sent within slot 210, such as a sidelink SSB, a sidelink CSI-RS, a sidelink SRS, and / or a sidelink positioning reference signal (PRS).

[0076] These physical channels are usually multiplexed and mapped to transport channels for processing at the medium access control (MAC) layer. Transport channels carry information blocks called transport blocks (TBs). The transport block size (TBS), which may correspond to the number of information bits, may be a controlled parameter based on the modulation and coding scheme (MCS) and the number of RBs in a given transmission.

[0077] Figure 2 The channels or carriers shown in are not necessarily all channels or carriers that may be used between devices, and one of ordinary skill in the art will recognize that other channels or carriers may be used in addition to those shown, such as other traffic, control, and feedback channels.

[0078] Figure 3An example of a wireless communication network 300 configured to support D2D or sidelink communications is shown. In some examples, the sidelink communications may include V2X communications. V2X communications involve not only direct wireless information exchange between vehicles (e.g., vehicles 302 and 304) themselves, but also direct information exchange between vehicles 302 / 304 and infrastructure (e.g., roadside units (RSUs) 306), infrastructure such as street lights, buildings, traffic cameras, toll booths or other fixed objects, vehicles 302 / 304 and pedestrians 308, and vehicles 302 / 304 and wireless communication networks (e.g., base stations 310). In some examples, V2X communications may be implemented in accordance with the New Radio (NR) cellular V2X standard defined in 3GPP Release 16 or other suitable standards.

[0079] V2X communication enables vehicles 302 and 304 to obtain information related to weather, nearby accidents, road conditions, activities of nearby vehicles and pedestrians, objects near the vehicle, and other relevant information that can be used to improve the vehicle driving experience and increase vehicle safety. For example, such V2X data can enable autonomous driving and improve road safety and traffic efficiency. For example, V2X-connected vehicles 302 and 304 can use the exchanged V2X data to provide in-vehicle collision warnings, road hazard warnings, approaching emergency vehicle warnings, pre- / post-collision warnings and information, emergency braking warnings, forward traffic jam warnings, lane change warnings, smart navigation services, and other similar information. In addition, V2X data received by the V2X-connected mobile device of the pedestrian / cyclist 308 can be used to trigger warning sounds, vibrations, flashing lights, etc. in the event of imminent danger.

[0080] V2X transmissions may include, for example, unicast transmissions, multicast transmissions, and broadcast transmissions. Unicast transmissions may include, for example, transmissions from a vehicle (e.g., vehicle 302) to one other vehicle (e.g., vehicle 304). Multicast transmissions may include, for example, transmissions when a group of UEs (e.g., vehicles 302 and 304) form a cluster. In this case, data may be multicast within the cluster. Broadcast transmissions may include, for example, transmissions from a UE (e.g., vehicle 302) to surrounding receivers (e.g., vehicle 304, roadside unit (RSU) 306, pedestrian / cyclist's mobile device 308, network (e.g., base station 310), or any combination thereof) adjacent to the transmitting UE.

[0081] Sidelink communications between vehicle-UEs (V-UEs) 302 and 304 or between a V-UE 302 or 304 and an RSU 306 or a pedestrian-UE (P-UE) 308 may be conducted via a sidelink 312 utilizing a Proximity Services (ProSe) PC5 interface. In various aspects of the present disclosure, the PC5 interface may also be used to support D2D sidelink 312 communications in other proximity use cases (e.g., in addition to V2X). Examples of other proximity use cases may include proximity services based on public safety or business (e.g., entertainment, education, office, medical, and / or interaction). In Figure 3 In the example shown, ProSe communication may further occur between UEs 314 and 316 .

[0082] ProSe communication can support different operation scenarios, such as in-coverage, out-of-coverage, and partial coverage. Out-of-coverage refers to a scenario in which UEs (e.g., UEs 314 and 316) are outside the coverage area of ​​a base station (e.g., base station 310), but each UE is still configured for ProSe communication. Partial coverage refers to a scenario in which some of the UEs (e.g., V-UE 304) are outside the coverage area of ​​the base station 310, while other UEs (e.g., V-UE 302 and P-UE 308) communicate with the base station 310. In-coverage refers to a scenario in which UEs (e.g., V-UE 302 and P-UE 308) communicate with the base station 310 (e.g., gNB) via a Uu (e.g., cellular interface) connection to receive ProSe service authorization and provisioning information to support ProSe operations.

[0083] In order to facilitate, for example, D2D sidelink communication between UEs 314 and 316 via sidelink 312, UEs 314 and 316 may transmit discovery signals therebetween. In some examples, each discovery signal may include a synchronization signal, such as a primary synchronization signal (PSS) and / or a secondary synchronization signal (SSS), which facilitates device discovery and synchronization of communications on sidelink 312. For example, UE 316 may utilize the discovery signal to measure the signal strength and channel state of a potential sidelink (e.g., sidelink 312) with another UE (e.g., UE 314). UE 316 may utilize the measurement results to select a UE (e.g., UE 314) for sidelink communication or relay communication.

[0084] In a 5G NR sidelink, the sidelink communication may utilize a transmit or receive resource pool. For example, the minimum resource allocation unit in frequency may be a subchannel (e.g., which may include, for example, 10, 15, 20, 25, 50, 75, or 100 consecutive resource blocks), and the minimum resource allocation unit in time may be a time slot. The radio resource control (RRC) configuration of the resource pool may be pre-configured (e.g., a factory setting of the UE determined by a sidelink standard or specification), or configured by a base station (e.g., base station 310).

[0085] In addition, for sidelink (e.g., PC5) communications, there may be two main resource allocation operating modes. In the first mode (mode 1), the base station (e.g., gNB) 310 can allocate resources to sidelink devices (e.g., V2X devices or other sidelink devices) in various ways for sidelink communications between sidelink devices. For example, the base station 310 can dynamically allocate sidelink resources (e.g., dynamic grants) to the sidelink devices in response to a request for sidelink resources by the sidelink devices. The base station 310 can further activate a pre-configured sidelink grant (e.g., a configured grant) for sidelink communications between sidelink devices. In mode 1, the transmitting sidelink device can report sidelink feedback back to the base station 310.

[0086] In the second mode (Mode 2), the sidelink devices can autonomously select sidelink resources for sidelink communications between them. In some examples, the transmitting sidelink device can perform resource / channel sensing to select unoccupied resources (e.g., subchannels) on the sidelink channel. The signaling on the sidelink is the same between the two modes. Therefore, from the receiver's perspective, there is no difference between the two modes.

[0087] In some examples, sidelink (e.g., PC5) communications may be scheduled using sidelink control information (SCI). SCI may include two SCI phases. Phase 1 sidelink control information (first phase SCI) may be referred to herein as SCI-1. Phase 2 sidelink control information (second phase SCI) may be referred to herein as SCI-2.

[0088] SCI-1 may be transmitted on a physical sidelink control channel (PSCCH). SCI-1 may include resource allocations for auxiliary link resources and information for decoding the second phase of auxiliary link control information (i.e., SCI-2). SCI-1 may also identify the priority (e.g., quality of service (QoS)) of the PSSCH. For example, an ultra-reliable low-delay communication (URLLC) service may have a higher priority than a text message service (e.g., a short message service (SMS) service). SCI-1 may also include physical sidelink shared channel (PSSCH) resource allocations and resource reservation periods (if enabled). In addition, SCI-1 may include a PSSCH demodulation reference signal (DMRS) mode (if more than one mode is configured). The receiver may use DMRS for radio channel estimation to demodulate the associated physical channel. As indicated, SCI-1 may also include information about SCI-2, for example, SCI-1 may disclose the format of SCI-2. Here, the format indicates the resource size of SCI-2 (e.g., the number of REs allocated to SCI-2), the number of PSSCH DMRS ports, and the modulation and coding scheme (MCS) index. In some examples, SCI-1 can use two bits to indicate the SCI-2 format. Therefore, in this example, four different SCI-2 formats can be supported. SCI-1 may include other information useful for establishing and decoding PSSCH resources.

[0089] SCI-2 may also be transmitted on the PSCCH and may include information for decoding the PSSCH. According to some aspects, SCI-2 includes a 16-bit Layer 1 (L1) destination identifier (ID), an 8-bit L1 source ID, a hybrid automatic repeat request (HARQ) process ID, a new data indicator (NDI), and a redundancy version (RV). For unicast communications, SCI-2 may further include a CSI report trigger. For multicast communications, SCI-2 may also include a zone identifier and a maximum communication range for NACK. SCI-2 may include other information useful for establishing and decoding PSSCH resources.

[0090] Figure 4A and Figure 4B is a diagram illustrating an example of a sidelink time slot structure according to some aspects. For example, the sidelink time slot structure can be used in a V2X or other D2D network implementing a sidelink. Figure 4A and Figure 4BIn the example shown, time is in the horizontal direction, with units of symbols 402 (e.g., OFDM symbols); frequency is in the vertical direction. Here, a carrier bandwidth 404 allocated for sidelink wireless communication is shown along the frequency axis. The carrier bandwidth 404 may include multiple subchannels, where each subchannel may include a configurable number of PRBs (e.g., 10, 14, 20, 24, 40, 44, or 100 PRBs).

[0091] Figure 4A and 4B Each of the figures shows an example of a respective time slot 400a or 400b including 14 symbols 402 that may be used for sidelink communications. However, it should be understood that sidelink communications may be configured to occupy less than 14 symbols in time slot 400a or 400b, and the present disclosure is not limited to any particular number of symbols 402. Each sidelink time slot 400a and 400b includes a physical sidelink control channel (PSCCH) 406 that occupies a control region 418 of time slots 400a and 400b and a physical sidelink shared channel (PSSCH) 408 that occupies a data region 420 of time slots 400a and 400b. The PSCCH 406 and PSSCH 408 are each transmitted on one or more symbols 402 of time slot 400a. The PSCCH 406 includes, for example, an SCI-1 that schedules the transmission of data traffic on the time-frequency resources of the corresponding PSSCH 408. As Figure 4A and Figure 4B As shown, PSCCH 406 and corresponding PSSCH 408 are transmitted in the same time slots 400a and 400b. In other examples, PSCCH 406 may schedule PSSCH in a subsequent time slot.

[0092] In some examples, the PSCCH 406 duration is configured to be two or three symbols. In addition, the PSCCH 406 can be configured to span a configurable number of PRBs, limited to a single subchannel. For example, the PSCCH 406 can span 10, 12, 14, 20, or 24 PRBs of a single subchannel. The DMRS can further appear in each PSCCH symbol. In some examples, the DMRS can be placed on every four REs of the PSCCH 406. Frequency domain orthogonal cover codes (FD-OCC) can be further applied to the PSCCH DMRS to reduce the impact of conflicting PSCCH transmissions on the side link channel. For example, the transmitting UE can randomly select a FD-OCC from a set of predefined FD-OCCs. Figure 4A and Figure 4B In each example shown, the starting symbol of the PSCCH 406 is the second symbol of the corresponding time slot 400a or 400b, and the PSCCH 406 spans three symbols 402.

[0093] PSSCH 408 may be time division multiplexed (TDMed) with PSCCH 406 and / or frequency division multiplexed (FDMed) with PSCCH 406. Figure 4A In the example shown, the PSSCH 408 includes a first portion 408a that is TDMed with the PSCCH 406 and a second portion 408b that is FDMed with the PSCCH 406. Figure 4B In the example shown, PSSCH 408 is TDMed with PSCCH 406 .

[0094] One and two layer transmissions of PSSCH 408 may be supported with various modulation orders (e.g., quadrature phase shift keying (QPSK), or quadrature amplitude modulation (QAM), such as 16-QAM, 64-QAM, and 246-QAM). In addition, PSSCH 408 may include DMRS 414 configured with a DMRS pattern of two, three, or four symbols. For example, Figure 4A The illustrated time slot 400a shows a two-symbol DMRS pattern, while Figure 4B The illustrated time slot 400b illustrates a three-symbol DMRS pattern. In some examples, depending on channel conditions, the transmitting UE may select a DMRS pattern and indicate the selected DMRS pattern in SCI-1. For example, the DMRS pattern may be selected based on the number of PSSCH 408 symbols in time slot 400a or 400b. In addition, in each time slot 400a and 400b, there is a gap symbol 416 after PSSCH 408.

[0095] Each time slot 400a and 400b also includes SCI-2 412, which is mapped to consecutive RBs in PSSCH 408 starting from the first symbol containing the PSSCH DMRS. Figure 4A In the example shown, the first symbol containing the PSSCH DMRS is the fifth symbol that occurs immediately after the last symbol carrying the PSCCH 406. Therefore, the SCI-2 412 is mapped to the RB within the fifth symbol. Figure 4B In the example shown, the first symbol containing the PSSCH DMRS is the second symbol, which also includes the PSCCH 406. In addition, the SCI-2 / PSSCH DMRS 412 is shown as spanning symbols 2 to 5. As a result, the SCI-2 / PSSCH DMRS 412 may be FDMed with the PSCCH 406 in symbols 2 to 4, and TDMed with the PSCCH 406 in symbol 5.

[0096] SCI-2 may be scrambled separately from the sidelink shared channel. In addition, SCI-2 may utilize QPSK. When the PSSCH transmission spans two layers, the SCI-2 modulation symbols may be replicated (e.g., repeated) on both layers. The SCI-1 in the PSCCH 406 may be blind decoded at the receiving wireless communication device. However, since the format, starting position, and number of REs of SCI-2 412 may be derived from SCI-1, blind decoding of SCI-2 is not required at the receiver (receiving UE).

[0097] exist Figure 4A and Figure 4B In each of the time slots 400a and 400b, the second symbol of each time slot 400a and 400b is copied (repeated) to its first symbol 410 for automatic gain control (AGC) settings. Figure 4A In , the second symbol including the PSCCH 406 FDMed with the PSSCH second part 408b may be sent on both the first symbol and the second symbol. Figure 4B In the example shown, the second symbol containing the PSCCH 406 FDMed with the SCI-2 / PSSCH DMRS 412 may be sent on both the first symbol and the second symbol.

[0098] Figure 5 is a diagram illustrating an example of a sidelink slot structure with feedback resources according to some aspects. For example, the sidelink slot structure can be used in a V2X or other D2D network implementing a sidelink. Figure 5 In the example shown, time is in the horizontal direction, with units of symbols 502 (e.g., OFDM symbols); frequency is in the vertical direction. Here, the carrier bandwidth 504 allocated for sidelink wireless communication is shown along the frequency axis. Figure 5 The slot 500 of the illustrated slot structure includes 14 symbols 502 that may be used for sidelink communications. However, it should be understood that sidelink communications may be configured to occupy less than 14 symbols in the slot 500 and the present disclosure is not limited to any particular number of symbols 502.

[0099] like Figure 4A and Figure 4B In the example shown, the sidelink time slot 500 includes a PSCCH 506 occupying the control region of the time slot 500 and a PSSCH 508 occupying the data region 520 of the time slot 500. The PSCCH 506 and the PSSCH 508 are each transmitted on one or more symbols 502 of the time slot 500a. The PSCCH 506 includes, for example, an SCI-1 that schedules the transmission of data traffic on the time-frequency resources of the corresponding PSSCH 508. Figure 5As shown, the starting symbol of PSCCH 506 is the second symbol of time slot 500, and PSCCH 506 spans three symbols 502. PSSCH 508 can be time division multiplexed (TDMed) with PSCCH 506, and / or frequency division multiplexed (FDMed) with PSCCH 506. Figure 5 In the example shown, the PSSCH 508 includes a first portion 508a that is TDMed with the PSCCH 506 and a second portion 508b that is FDMed with the PSCCH 506 .

[0100] The PSSCH 508 may also include a DMRS 514 configured in a DMRS pattern of two, three, or four symbols. Figure 5 The illustrated time slot 500 shows a two-symbol DMRS pattern. In some examples, depending on channel conditions, the transmitting UE can select a DMRS pattern and indicate the selected DMRS pattern in SCI-1. For example, the DMRS pattern can be selected based on the number of PSSCH 508 symbols in the time slot 500. In addition, the gap symbol 516 appears after the PSSCH 508 in the time slot 500.

[0101] The time slot 500 also includes SCI-2 512, which is mapped to consecutive RBs in the PSSCH 508 starting from the first symbol containing the PSSCH DMRS. Figure 5 In the example shown, the first symbol containing the PSSCH DMRS is the fifth symbol that occurs immediately after the last symbol carrying the PSCCH 506. Therefore, the SCI-2 512 is mapped to the RB within the fifth symbol.

[0102] In addition, if Figure 5 As shown, the second symbol of time slot 500 is copied (repeated) to its first symbol 510 for automatic gain control (AGC) setting. Figure 5 In the example, a second symbol including the PSCCH 506 FDMed with the PSSCH second part 508b may be sent on both the first symbol and the second symbol.

[0103] HARQ feedback may also be sent on a physical sidelink feedback channel (PSFCH) 518 in a configurable resource period of 0, 1, 2, or 4 slots. In a sidelink slot (e.g., slot 500) containing a PSFCH 518, one symbol 502 may be allocated to the PSFCH 518, and the PSFCH 518 may be copied (repeated) to the previous symbol for AGC settings. Figure 5In the example shown, the PSFCH 518 is transmitted on the thirteenth symbol and is copied on the twelfth symbol in the slot 500c. A gap symbol 516 may be further placed after the PSFCH symbol 518.

[0104] In some examples, there is a mapping between PSSCH 508 and the corresponding PSFCH resources. The mapping can be based on, for example, the starting subchannel of PSSCH 508, the time slot containing PSSCH 508, the source ID, and the destination ID. In addition, PSFCH can be enabled for unicast and multicast communications. For unicast, PSFCH can include an ACK / NACK bit. For multicast, PSFCH may have two feedback modes. In the first multicast PSFCH mode, the receiving UE only sends NACK, while in the second multicast PSFCH mode, the receiving UE can send ACK or NACK. The number of available PSFCH resources can be equal to or greater than the number of UEs in the second multicast PSFCH mode.

[0105] As described above, a UE operating in a wireless communication network (e.g., a D2D network, a V2X network, etc.) may reserve at least one resource for communication of a direct signal (e.g., a transmission to another UE). In some examples, the UE broadcasts sidelink control information (SCI) to notify other UEs in the network that the UE has reserved at least one resource. Thus, each UE in the network may detect the SCI sent by other UEs to determine which resources have not been reserved (e.g., will be free for use). In some examples, the SCI is the NR V2X equivalent of the Scheduling Assignment (SA) used in 3GPP Long Term Evolution (LTE) V2X. As discussed herein, a UE of the network may include, for example, a UE installed in a wireless communication network such as a LTE V2X. Figure 2 An onboard V2X unit in a vehicle, cellular phone, laptop, wearable device, or other suitable wireless communication device is shown.

[0106] Figure 6 602 is a diagram illustrating an example of resource allocation 602 for such a network over a period of time. Here, time resources (e.g., time slots) and frequency resources (e.g., subcarriers) are allocated for signal transmission by UEs (not shown) of the network. The SCI may indicate that one or more resources are reserved for one or more transmissions. For example, a first resource may be reserved for a first transmission, a second resource may be reserved for a second transmission, and so on. Figure 6 In the example of , the first SCI 604 sent by the first UE indicates that the first resource 606 is reserved for the first transmission, and the second resource 608 is reserved for the second transmission. Similarly, the second SCI 610 sent by the second UE indicates that the first resource 612 is reserved for the first transmission and the second resource 614 is reserved for the second transmission.

[0107] The SCI scheme may support a retransmission scheme, such as a hybrid automatic repeat request (HARQ) scheme. In a retransmission scheme, the UE may retransmit information sent in a first transmission in an attempt to ensure that any intended receiver will be able to decode the information. For example, if applicable, the receiver may use a HARQ combination of the first transmission and at least one retransmission to decode the information.

[0108] Thus, the SCI may indicate reserved resources for a transmission and one or more reserved resources for one or more potential retransmissions. Thus, each second transmission mentioned above may be a retransmission of a corresponding first transmission (e.g., for HARQ tracking combining (HARQ-CC) or HARQ incremental redundancy (HARQ-IR)). In addition, the UE may indicate resources reserved for one or more subsequent retransmissions in a subsequent transmission (e.g., in scheduling information associated with the retransmission).

[0109] In some examples, the UE may detect SCI sent by other UEs so that the UE will know which resources are currently reserved for a period of time.In a sidelink network, the UE may detect the SCI on a physical sidelink control channel (PSCCH) or some other type of channel.

[0110] In some examples, a UE may use a threshold to determine whether to consider a particular SCI for the purpose of resource reservation. A first UE may receive SCI (and other signals) from a second UE that is relatively far away from the first UE. In this case, the received signal strength of such signaling at the first UE may be relatively low. Therefore, any potential interference (e.g., signaling conflict) between the first UE and the second UE (e.g., if the two UEs transmit simultaneously) may be relatively small. For example, despite the presence of interference, the corresponding receivers of these transmissions may be able to successfully decode the transmissions. Therefore, if the first UE determines that the received signal strength of the signal from the second UE is below a threshold (e.g., "X" dB), the first UE may ignore the SCI from the second UE. In some examples, such a threshold (e.g., which may be referred to as a resource reservation threshold) may be configured by the network. In some examples, the determination of the received signal strength includes measuring the received signal strength of a PSCCH signal and / or a physical sidelink shared channel (PSCCH) signal. In some examples, the determination of the received signal strength includes measuring the reference signal received power (RSRP).

[0111] When a UE has information to send over a direct link, the UE may identify candidate resources for transmission for a specific time period. Candidate resources include resources that can accommodate the transmission and are available for use. In some examples, the resources that can accommodate the transmission may include resources that are large enough to accommodate the size of the packet to be transmitted. In some examples, the resources available for use may include resources that are not reserved by another UE. In some examples, the resources available for use may also include resources reserved by the UE, but the corresponding received signal strength of the UE is below a resource reservation threshold.

[0112] As described above, a group of UEs may form a group, wherein information is multicast to the UEs of the group. Figure 7 is a diagram showing an example of a direct wireless communication system 700 including a group of UEs. The direct wireless communication system 700 may include, for example, one or more of a D2D wireless communication network, a V2X or V2P wireless communication network, a P2P wireless communication network (e.g., Bluetooth), some other direct wireless communication network, or a combination thereof.

[0113] The direct wireless communication system 700 includes a first UE 702a, a second UE 702b, a third UE 702c, a fourth UE 702d, a fifth UE 704, and a sixth UE 706. Each of the first UE 702a-fourth UE 702d may include, for example, a Figure 3 The vehicle-mounted V2X unit in the vehicle shown, or some other wireless communication device currently in the vehicle (e.g., Figure 1 , 3 , 5, 8, 9 and 11). The fifth UE 704 may include, for example, Figure 1 , 3 , 5, 8, 9 and 11 as shown in any of the cellular phone, laptop computer, wearable device or some other type of wireless communication device. For example, the sixth UE 706 may include such Figure 3 The infrastructure equipment shown or some other type of wireless communication equipment (e.g., Figure 1 , 3 , 5, 8, 9 and 11).

[0114] exist Figure 7In the example of , the first UE 702a, the second UE 702b, the third UE 702c and the fourth UE 702d form a group 708. In some examples, the first UE 702a, the second UE 702b, the third UE 702c and the fourth UE 702d can communicate with each other through their respective direct links (e.g., side links, P2P links, D2D links or other suitable direct links). For example, the first UE 702a and the second UE 702b can communicate via link 710a, the third UE 702c and the fourth UE 702d can communicate via link 710b, and so on. In addition, the first UE 702a, the second UE 702b, the third UE 702c and the fourth UE 702d can transmit a groupcast message via one or more links (e.g., as shown in link 710c). In some examples, the groupcast message can have a range requirement. For example, the message may be targeted only to those UEs (eg, members of the group) that are within a certain range of the UE sending the message (eg, a certain distance from the UE).

[0115] As discussed herein, transmissions by any UE in the group 708 may or may not interfere with communications by the fifth UE 704. For example, transmissions by a fourth UE 702d that is relatively close to the fifth UE 704 may interfere with communications by the fifth UE 704 (e.g., the RSRP of a signal from the fourth UE 702d measured by the fifth UE 704 may be relatively high). Conversely, transmissions by a first UE 702a that is not relatively close to the fifth UE 704 may not interfere with communications by the fifth UE 704 (e.g., the RSRP of a signal from the first UE 702a measured by the fifth UE 704 may be relatively low). Thus, in some examples, resource reservations by the fifth UE 704 may take into account resource reservations (e.g., SCI signaling) by the UEs of the group 708.

[0116] In some examples, the multicast communication in group 708 can employ feedback to improve the efficiency and / or reliability of the multicast communication. For example, a UE of group 708 that sends a multicast message can determine whether to retransmit the message based on feedback from other members of group 708. Here, the UEs of the group can determine that the first UE of the group is sending a multicast message based on an SCI sent by the first UE of the group. Therefore, the UEs of the group (e.g., UEs within the range requirement of the message) can attempt to decode the multicast transmission on the resources indicated by the SCI.

[0117] The first type of feedback-based retransmission for multicast may be referred to as Option 1 multicast feedback. In Option 1, a UE that does not successfully receive an expected multicast message sends a negative acknowledgement (NACK). For example, the UE may send a specified feedback sequence on a feedback channel. In some examples, the feedback channel is a physical sidelink feedback channel (PSFCH).

[0118] In contrast, in Option 1, UEs that successfully receive the intended multicast message do not send any feedback. In some examples, this feedback mechanism may be relatively efficient because no additional signal is sent if the transmission is successful (e.g., if all UEs in the group that expect the message successfully receive the message, no feedback is sent).

[0119] Figure 8 is a signaling diagram illustrating an example of option 1 multicast feedback within a direct wireless communication system 800. The wireless communication system 800 may correspond to, for example Figure 1 , Figure 3 , Figure 7 and Fig. 9 The direct wireless communication system 800 may include, for example, one or more of a D2D wireless communication network, a V2X / V2P wireless communication network, a P2P wireless communication network (eg, Bluetooth), and / or other direct wireless communication networks.

[0120] The direct wireless communication system 800 includes a plurality of groupcast UEs (GC UEs): a first UE 802a, a second UE 802b, a third UE 802c, and a fourth UE 802d. Each of the UEs 802a-802d may be, for example, Figure 1 , Figure 3 , Figure 7 , Fig. 9 and Fig.11 In some examples, the first UE 802a, the second UE 802b, the third UE 802c, and the fourth UE 802d may correspond to Figure 7 The first UE 702a, the second UE 702b, the third UE 702c and the fourth UE 702d.

[0121] At 804, a first UE 802a (e.g., GC UE 0) may reserve a first resource (resource 1) for a multicast transmission (multicast option 1) and, if applicable, at least one second resource (resource 2) for at least one potential retransmission of the first transmission. For example, in the event that the multicast transmission is unsuccessful, the first UE 802a may reserve resources for HARQ retransmissions.

[0122] At 806, the first UE 802a may send (eg, broadcast) an SCI. In some examples, the SCI indicates that the first UE 802a has reserved resource 1 for multicast option 1 transmission and reserved resource 2 for potential retransmissions of the multicast retransmission.

[0123] At 808, the first UE 802a may send a multicast option 1 message to UEs 802b-802d via resource 1. The message is successfully received by the second UE 802b and the fourth UE 802d. Therefore, the second UE 802b and the fourth UE 802d do not send a negative acknowledgement (NACK).

[0124] However, the third UE 802c does not successfully receive the multicast option 1 message. Therefore, at 810, the third UE 802c sends a NACK on a feedback channel (eg, PSFCH).

[0125] At 812, as a result of receiving at least one NACK in response to the multicast option 1 message, the first UE 802a retransmits the multicast option 1 message to UEs 802b-802d via resource 2.

[0126] As described above, in Option 1, if a UE sending a multicast message does not receive any feedback, it can be assumed that all intended recipients of the message successfully received the transmission. Therefore, the UE will not retransmit the message (e.g., to prevent unnecessary signaling). Figure 8 In the example, if the third UE 802c does not send a NACK at 810, the first UE 802a will not retransmit the message at 812.

[0127] The second type of feedback-based multicast retransmission may be referred to as Option 2 multicast feedback. In Option 2, a UE that expects to receive a multicast message sends feedback indicating whether the UE successfully received the message. For example, a UE that successfully receives an expected multicast message may send a positive acknowledgement (ACK). Conversely, a UE that does not successfully receive an expected multicast message may send a NACK. For example, the UE may send a corresponding specified feedback sequence on a feedback channel. In some examples, the feedback channel is a physical sidelink feedback channel (PSFCH).

[0128] In some examples, the UE that sent the message will retransmit unless it receives explicit feedback from each intended receiver indicating that the message was successfully received. This is in contrast to Option 1, where a UE that did not successfully receive a multicast message may not send a NACK. For example, when a first UE sends an SCI indicating that a multicast message will be sent, a second UE may already be sending. Therefore, if the second UE fails to decode the message, it may not attempt to decode the message or send a NACK.

[0129] Fig. 9 is a signaling diagram illustrating an example of option 2 multicast feedback within a direct wireless communication system 900. The wireless communication system 900 may correspond to, for example Figure 1 , Figure 3 , Figure 7 and Figure 8 The direct wireless communication system 900 may include, for example, one or more of a D2D wireless communication network, a V2X / V2P wireless communication network, a P2P wireless communication network (eg, Bluetooth), and / or other direct wireless communication networks.

[0130] The direct wireless communication system 900 includes a plurality of groupcast UEs (GC UEs): a first UE 902a, a second UE 902b, a third UE 902c, and a fourth UE 902d. For example, each of the UEs 902a-902d may be a UE such as Figure 1 , Figure 3 , Figure 7 , Figure 8 and Fig.11 In some examples, the first UE 902a, the second UE 902b, the third UE 902c, and the fourth UE 902d may correspond to Figure 7 The first UE 702a, the second UE 702b, the third UE 702c and the fourth UE 702d.

[0131] At 904, a first UE 902a (e.g., GC UE 0) may reserve a first resource (resource 1) for a multicast transmission (multicast option 2) and, if applicable, at least one second resource (resource 2) for at least one potential retransmission of the first transmission. For example, in the event that the multicast transmission is unsuccessful, the first UE 902a may reserve resources for HARQ retransmissions.

[0132] At 906, the first UE 902a may send (e.g., broadcast) an SCI. In some examples, the SCI indicates that the first UE 902a has reserved a first resource (resource 1) for multicast option 2 transmission and at least one second resource (resource 2) for at least one potential retransmission of the multicast retransmission.

[0133] At 908, the first UE 902a may send a multicast option 2 message to UEs 902b-902d via resource 1.

[0134] The second UE 902b successfully receives the multicast option 2 message. Therefore, at 910a, the second UE 902b sends a positive acknowledgement (ACK) on a feedback channel (eg, PSFCH).

[0135] The third UE 902c successfully receives the multicast option 2 message. Therefore, at 910b, the third UE 902c sends an ACK on a feedback channel (eg, PSFCH).

[0136] The fourth UE 902d does not successfully receive the multicast option 2 message. Therefore, at 910c, the fourth UE 902d sends a NACK on a feedback channel (eg, PSFCH).

[0137] At 910, as a result of not receiving an ACK in response to the multicast option 2 message from each of the second UE 902b, the third UE 902c and the fourth UE 902d (or, as a result of receiving at least one NACK), the first UE 902a retransmits the multicast option 2 message to UEs 902b-902d via resource 2.

[0138] As described above, in Option 2, if a UE sending a multicast message receives ACKs from all intended recipients of the message, the UE does not retransmit the message (e.g., to prevent unnecessary signaling). Fig. 9 In the example, if the fourth UE 902d sends an ACK instead of a NACK at 910c, the first UE 902a will not retransmit the message at 912.

[0139] According to the above, it should be understood that in Option 1 and Option 2, the first UE (eg, Figure 8 The first UE 802a or Fig. 9 The resources scheduled for retransmission by the first UE 902a) remain scheduled even if the UE does not retransmit. However, the nearby UEs (e.g., Figure 7 The fifth UE 704) may still expect the first UE to use at least one second resource for at least one retransmission. Therefore, the fifth UE 704 (and any other nearby UEs) may not attempt to select any resource overlapping with the at least one second resource. Therefore, resources in the system may be wasted.

[0140] To address this potential waste of resources, the UE may be configured to detect feedback associated with the first transmission (e.g., for option 1 or option 2 multicast feedback). In this way, the UE may determine whether there will be a retransmission. If there will be no retransmission, the UE may choose to use resources that overlap with resources previously reserved for the retransmission (e.g., the UE may reclaim the resources).

[0141] In some examples, for option 1 multicast feedback, the first UE may monitor the feedback channel for a negative feedback sequence (e.g., NACK) associated with the first transmission of the second UE. If no negative feedback sequence is sent for the first transmission, the first UE may determine that the second UE will not send a retransmission on the resources that the second UE previously reserved for the retransmission. Therefore, the first UE may attempt to select resources that overlap with the previously reserved resources.

[0142] In some examples, for option 2 multicast feedback, the first UE may monitor the feedback channel for positive feedback sequences (e.g., ACK) and / or negative feedback sequences (e.g., NACK) associated with the first transmission of the second UE. If all feedback sequences sent for the first transmission are positive feedback sequences, the first UE may determine that the second UE will not send a retransmission on resources that the second UE previously reserved for retransmissions. Therefore, the first UE may attempt to select resources that overlap with previously reserved resources.

[0143] However, in some scenarios, the UE may expend considerable resources to detect feedback. For example, if there are a large number of nearby UEs using option 2 multicast feedback, it may be undesirable (e.g., impractical) for the UE to detect (e.g., receive and decode) all feedback sequences sent by all nearby UEs. In addition, in some cases, the UE may not be able to or may not be configured to decode a feedback sequence sent by another UE. For example, a UE that must send feedback may not be able to detect feedback at the same time.

[0144] The present disclosure relates in some aspects to reducing feedback monitoring at a UE.For example, a first UE may choose not to detect feedback associated with transmissions of certain UEs.

[0145] In some examples, the utilization of feedback resources may be relatively low (eg, 10% to 30%). In addition, as described above, the negative impact of interference between UEs that are relatively far from each other may be relatively minimal.

[0146] Thus, selective feedback detection at the first UE may be based on the received signal strength of the signal received from the second UE. For example, if the RSRP measured at the first UE for the signal received from the second UE is below a threshold, the first UE may choose not to detect feedback associated with the second UE's transmission. Here, since the distance between the first UE and the second UE is relatively far (as indicated by the relatively low RSRP measured at the first UE), the interference between the first UE and the second UE may be relatively low. Therefore, the first UE may consider any resources reserved by the second UE for retransmission as available to the first UE. Therefore, the first UE may include at least one resource overlapping with the reserved resources in the candidate set (e.g., assuming that any other resource conditions are met) without detecting feedback associated with the second UE's first transmission. Therefore, in this case, the SCI detection process at the first UE may be more efficient (e.g., the first UE will not process as many feedback sequences).

[0147] Fig.10 1 is a flow chart of a method 1000 for scheduling resources for a UE according to some aspects. As described below, some or all of the illustrated features may be omitted in certain implementations within the scope of the present disclosure, and some of the illustrated features may not be necessary for all example implementations. In some examples, the method may be performed by a wireless communication device 1100 (e.g., by a processing system 1114), as described above and as Fig.11 As shown, it is executed by a processor or a processing system, or by any suitable means for performing the functions described.

[0148] At block 1002, a first UE may receive a signal from a second UE. For example, for reselection purposes, the first UE may monitor PSCCH signaling and / or PSSCH signaling.

[0149] At block 1004, the first UE may receive an SCI sent by the second UE. In some examples, if applicable, the SCI may indicate that the second UE has reserved a first resource of the plurality of resources for a multicast transmission and at least one second resource of the plurality of resources for at least one retransmission of the multicast transmission.

[0150] At block 1006 , the first UE may determine a received signal strength of the received signal (eg, measure the signal strength of the signal). For example, the first UE may determine an RSRP indication of the signal received at block 1002 .

[0151] At block 1008, the first UE begins operations to determine a candidate set of idle resources. For example, the first UE may perform the following operations to identify at least one available resource for the candidate set.

[0152] At block 1010, the first UE determines whether the signal strength determined at block 1004 is greater than or equal to a threshold. For example, the first UE may determine whether the second UE is far enough from the first UE (e.g., such that communications of the UEs do not significantly interfere with each other) based on the signal strength.

[0153] In some examples, the threshold value may be configured by the network. For example, the network may determine the threshold value to be used (e.g., based on measurements and / or simulations) and send an indication of the threshold value to the first UE. In some examples, the threshold value may be specified by a communication standard or specification (e.g., a D2D standard or specification).

[0154] In some examples, the threshold can be based on the resource reservation threshold discussed herein.For example, the threshold can be set to a value equal to the resource reservation threshold plus an increment (eg, in dB).

[0155] In some examples, the threshold value may be based on the traffic load in the network. For example, the threshold value may be set to a value that varies based on the traffic load. In some examples, the traffic load indicator may take the form of a channel busyratio (CBR). As an example, when the traffic load is light, a first threshold value (e.g., 5 dB above the resource reservation threshold value) may be used, when the traffic load is medium, a second threshold value (e.g., 10 dB above the resource reservation threshold value) may be used, and when the traffic load is heavy, a third threshold value (e.g., 10-15 dB above the resource reservation threshold value) may be used. In other examples, other relationships between traffic load and threshold values ​​may be used.

[0156] In some examples, a threshold may be defined to attempt to ensure that a certain percentage of available resources remain idle. For example, a threshold may be set to a value such that a certain percentage (e.g., 50%) of allocated V2X resources remain idle. In some examples, the determination may be based on resource information collected over a period of time, and based on the threshold used during that period of time.

[0157] If the signal strength is not greater than or equal to the threshold at block 1010 (e.g., the second UE is far enough away), the first UE does not detect feedback associated with the second UE's multicast transmission. Instead, the operational flow proceeds to block 1012, where the first UE includes at least one resource in the candidate set that overlaps with at least one second resource. In this case, the first UE may then choose to use the resource for transmission regardless of whether the second UE will transmit on the resource (e.g., the UE may reclaim at least one second resource).

[0158] If the signal strength is greater than or equal to the threshold at block 1010 (e.g., the second UE is not far enough away), operational flow proceeds to block 1014 where the first UE determines the type of multicast scheduled by the SCI received at block 1006. In some examples, the second UE may indicate the type of multicast in control information sent by the second UE (e.g., on the PSCCH).

[0159] If it is determined at block 1014 that the multicast is an option 1 multicast, operational flow proceeds to block 1016 where the first UE monitors the feedback channel to determine whether at least one NACK is sent in response to the option 1 multicast. In some examples, the second UE may indicate which feedback sequences are applicable to the multicast in control information sent by the second UE (e.g., on the PSCCH).

[0160] If the UE determines at block 1016 that a NACK was not sent in response to the option 1 multicast, then the second UE is not expected to send a retransmission on the at least one second resource. Therefore, operational flow proceeds to block 1012, where the first UE includes at least one resource overlapping with the at least one second resource in the candidate set.

[0161] Conversely, if it is determined at block 1016 that at least one NACK was sent in response to the option 1 multicast, the operational flow proceeds to block 1018. Here, it is expected that the second UE sends a retransmission on the at least one second resource. Since the at least one second resource is unavailable, the first UE will not include any resource of the at least one second resource in the candidate set. In addition, the first UE can continue to monitor other available resources (e.g., the operational flow can return to block 1002).

[0162] If it is determined at block 1014 that the multicast is an option 2 multicast, operational flow proceeds to block 1020 where the first UE monitors the feedback channel to determine whether all expected ACKs are sent in response to the option 2 multicast. If so (e.g., the second UE is not expected to send a retransmission on the at least one second resource), operational flow proceeds to block 1012 where the first UE includes in the candidate set at least one resource that overlaps with the at least one second resource.

[0163] In contrast, if it is determined at block 1020 that not all ACKs were sent (or at least one NACK was sent) in response to the option 2 multicast, then operational flow proceeds to block 1018, where the first UE will not include any resource of the at least one second resource in the candidate set. Additionally, the first UE may continue to monitor other available resources (e.g., operational flow may return to block 1002).

[0164] In view of the above, it can be seen that the first UE can use method 1000 to efficiently select resources for the candidate set because detection feedback can be avoided in some cases. Therefore, UEs in the network can select from a larger pool of conflict-free resources, thereby improving the efficiency and performance of the network.

[0165] Fig.11 1 is a conceptual diagram illustrating an example of a hardware implementation for a wireless communication device 1100 that employs a processing system 1114. For example, the wireless communication device 1100 may be Figure 1 , Figure 3 and Figure 7-Figure 9 UE, D2D device or V2X device shown in any of the figures.

[0166] The wireless communication device 1100 may be implemented with a processing system 1114 including one or more processors 1104. Examples of processors 1104 include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout the present disclosure. In various examples, the wireless communication device 1100 may be configured to perform any one or more functions described herein. That is, the processor 1104 used in the wireless communication device 1100 may be used to implement any one or more of the processes described below. In some cases, the processor 1104 may be implemented via a baseband or modem chip, and in other implementations, the processor 1104 itself may include multiple devices different from the baseband or modem chip (for example, in this case, these devices may work together to implement the examples discussed herein). As described above, various hardware arrangements and components other than the baseband modem processor may be used in the implementation, including RF chains, power amplifiers, modulators, buffers, interleavers, adders / summers, etc.

[0167] In this example, the processing system 1114 can be implemented with a bus architecture, generally represented by bus 1102. Depending on the specific application and overall design constraints of the processing system 1114, the bus 1102 may include any number of interconnecting buses and bridges. The bus 1102 communicatively couples various circuits together, including one or more processors (generally represented by processor 1104), memory 1105, and computer-readable media (generally represented by computer-readable media 1106). The bus 1102 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and are not described further. The bus interface 1108 provides an interface between the bus 1102 and the transceiver 1110. The transceiver 1110 provides components for communicating with various other devices over a transmission medium (e.g., an air interface). A user interface 1112 (e.g., a keypad, a display, a speaker, a microphone, a joystick) may also be provided.

[0168] The processor 1104 is responsible for managing the bus 1102 and general processing, including executing software stored on the computer-readable medium 1106. When executed by the processor 1104, the software causes the processing system 1114 to perform the various functions described below for any particular device. The computer-readable medium 1106 and the memory 1105 can also be used to store data manipulated by the processor 1104 when executing the software. For example, the memory 1105 can store threshold information 1115 (e.g., for signal measurement) that the processor 904 uses in cooperation with the transceiver 910 to control the communication operations described herein.

[0169] One or more processors 1104 in the processing system can execute software. Software should be broadly interpreted as instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable programs, execution threads, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium 1106.

[0170] Computer readable medium 1106 may be a non-transitory computer readable medium. For example, non-transitory computer readable media include magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips), optical disks (e.g., compact disks (CDs) or digital versatile disks (DVDs)), smart cards, flash memory devices (e.g., cards, sticks, or key drives), random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, removable disks, and any other suitable devices. Computer readable media may also include carrier waves, transmission lines, and any other suitable medium for transmitting software and / or instructions that can be accessed and read by a computer. Computer readable medium 1106 may reside in processing system 1114, external to processing system 1114, or distributed among multiple entities including processing system 1114. Computer readable medium 1106 may be embodied in a computer program product. In some examples, computer readable medium 1106 may be part of memory 1105. For example, a computer program product may include a computer readable medium in packaging material. Those skilled in the art will recognize how to best implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

[0171] In some aspects of the present disclosure, the processor 1104 may include circuits configured for various functions. For example, the processor 1104 may include circuits configured for executing Fig.10 In some aspects, the processor 1104 may include circuitry for executing the method 1000 of the present invention. Figure 6-Figure 10 and Figure 12-Figure 18 One or more operations of a circuit are described.

[0172] Processor 1104 may include communication and processing circuitry 1141 configured to communicate with a base station and one or more other wireless communication devices via a common carrier shared between a cellular (e.g., Uu) interface and a sidelink (e.g., PC5) interface. In some examples, communication and processing circuitry 1141 may include one or more hardware components that provide a physical structure for performing processes associated with wireless communication (e.g., signal reception and / or signal transmission) and signal processing (e.g., processing received signals and / or processing signals for transmission). Communication and processing circuitry 1141 may also be configured to execute communication and processing software 1151 stored on computer-readable medium 1106 to implement one or more functions described herein.

[0173] In some implementations where communication involves receiving information, the communication and processing circuitry 1141 may obtain information from a component of the wireless communication device 1100 (e.g., from a transceiver 1110 that receives information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium), process (e.g., decode) the information, and output the processed information. For example, the communication and processing circuitry 1141 may output the information to another component of the processor 1104, the memory 1105, or the bus interface 1108. In some examples, the communication and processing circuitry 1141 may receive one or more of a signal, a message, an SCI, feedback, other information, or any combination thereof. In some examples, the communication and processing circuitry 1141 may receive information via one or more of a PSCCH, a PSSCH, a PSFCH, some other type of channel, or any combination thereof. In some examples, the communication and processing circuitry 1141 may include functionality of a component for receiving (e.g., a component for receiving a signal and / or a component for receiving control information). In some examples, communications and processing circuitry 1141 may include functionality of components for decoding.

[0174] In some implementations where the communication involves sending (e.g., transmitting) information, the communication and processing circuit 1141 may obtain the information (e.g., from another component of the processor 1104, the memory 1105, or the bus interface 1108), process (e.g., encode) the information, and output the processed information. For example, the communication and processing circuit 1141 may output the information to the transceiver 1110 (e.g., the transceiver 1110 sends the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium). In some examples, the communication and processing circuit 1141 may send one or more of a signal, a message, an SCI, feedback, other information, or any combination thereof. In some examples, the communication and processing circuit 1141 may send information via one or more of a PSCCH, a PSSCH, a PSFCH, some other type of channel, or any combination thereof. In some examples, the communication and processing circuit 1141 may include the functionality of a component for sending (e.g., a component for transmitting). In some examples, the communication and processing circuit 1141 may include the functionality of a component for encoding.

[0175] Processor 1104 may also include signal processing circuitry 1142 configured to determine an RSRP associated with a signal (e.g., measure a signal strength of the signal). In some examples, signal processing circuitry 1142 may be configured to perform one or more signal processing-related operations described herein (e.g., including in conjunction with Figure 6 – Fig.101142 may include the functionality of a component for receiving a signal. For example, the signal processing circuit 1142 may monitor the PSCCH and / or the PSSCH and decode the signaling received on the PSCCH and / or the PSSCH. In some examples, the signal processing circuit 1142 may include the functionality of a component for measuring signal strength. For example, the signal processing circuit 1142 may generate an RSRP indication by monitoring (e.g., over a period of time) the PSCCH and / or the PSSCH. In some examples, the signal processing circuit 1142 may provide a reference signal received power indication by monitoring one or more reference signals. The signal processing circuit 1142 may also be configured to execute signal processing software 1152 stored on the computer-readable medium 1106 to implement one or more functions described herein.

[0176] Processor 1104 may also include dynamic detection circuit 1143, which is configured to determine whether to detect feedback associated with the transmission. In some examples, dynamic detection circuit 1143 may be configured to perform one or more detection-related operations described herein (e.g., including combining Figure 6 – Fig.10 In some examples, the dynamic detection circuit 1143 may include functionality of components for decoding feedback or avoiding detecting feedback. In some examples, the dynamic detection circuit 1143 may include functionality of components for determining whether to detect feedback. In some examples, the dynamic detection circuit 1143 may include functionality of components for determining whether to detect a channel. For example, the dynamic detection circuit 1143 may determine whether to detect (e.g., monitor and decode) feedback from multicast group members in response to a multicast transmission based on a received signal strength indication. In some examples, if the received signal strength is greater than or equal to a threshold, the dynamic detection circuit 1143 selects to detect feedback. Otherwise, the dynamic detection circuit 1143 may choose not to detect feedback. The dynamic detection circuit 1143 may also be configured to execute dynamic detection software 1153 stored on the computer-readable medium 1106 to implement one or more functions described herein.

[0177] Processor 1104 may also include resource selection circuitry 1144 configured to select resources for communication by wireless communication device 1100. In some examples, signal processing circuitry 1142 may be configured to perform one or more resource selection related operations described herein (e.g., including in conjunction with Figure 6 – Fig.10In some examples, the resource selection circuit 1144 may include the functionality of a component for performing a resource selection operation. In some examples, the resource selection circuit 1144 may include the functionality of a component for determining a candidate set. In some examples, the resource selection circuit 1144 may include the functionality of a component for determining whether at least one resource overlapping with at least one second resource is included in the candidate set. In some examples, the resource selection circuit 1144 may include the functionality of a component for scheduling communications. In some examples, the resource selection circuit 1144 may include the functionality of a component for determining whether the wireless communication device will perform a retransmission. In some examples, the resource selection circuit 1144 may include the functionality of a component for determining whether to schedule communications. In some examples, the resource selection circuit 1144 may include the functionality of a component for defining a threshold. For example, the resource selection circuit 1144 may determine whether to include at least one resource in the candidate set based on a received signal strength indication (and optionally, feedback from a multicast group member), the at least one resource overlapping a resource previously reserved by another wireless communication device for a retransmission of a multicast transmission. If the received signal strength associated with the other wireless communication device is less than or equal to the threshold, the resource selection circuit 1144 may include at least one resource in the candidate set that overlaps with a resource previously reserved for retransmission by the other wireless communication device without detecting feedback associated with the transmission of the other wireless communication device. Alternatively, the resource selection circuit 1144 may determine whether to include at least one resource in the candidate set that overlaps with a resource previously reserved for retransmission by the wireless communication device based on feedback associated with the transmission of the other wireless communication device. The resource selection circuit 1144 may also be configured to execute resource selection software 1154 stored on the computer-readable medium 1106 to implement one or more functions described herein.

[0178] Fig.12 1 is a flow chart of a method 1200 for a wireless communication device according to some aspects. As described below, some or all of the illustrated features may be omitted in certain implementations within the scope of the present disclosure, and some of the illustrated features may not be necessary for all example implementations. In some examples, the method 1200 may be performed by the wireless communication device 1100 (e.g., by the processing system 1114), as described above and as shown below. Fig.11 As shown, it is executed by a processor or processing system, or by any suitable means for performing the functions described.

[0179] At block 1202, a first wireless communication device may receive a signal from a second wireless communication device. In some examples, receiving a signal from a second wireless communication device may include receiving a signal via a physical sidelink control channel (PSCCH) or a physical sidelink shared channel (PSSCH). Fig.11 The communication and processing circuitry 1141 and transceiver 1110 shown and described may monitor at least one of PSCCH signaling, PSSCH signaling, other signaling, or a combination thereof from a second wireless communication device.

[0180] At block 1204, the first wireless communication device may measure the signal strength of the signal. Fig.11 The signal processing circuit 1142 and / or the communication and processing circuit 1141 shown and described may process the signal received at block 1202 to determine a received signal strength of the signal. In some examples, the signal strength is a reference signal received power (RSRP).

[0181] At block 1206, the first wireless communication device may receive control information (e.g., sidelink control information) indicating that the second wireless communication device has reserved a first resource from among the plurality of resources for a first transmission to at least one third wireless communication device and has reserved at least one second resource from among the plurality of resources for at least one retransmission to at least one third wireless communication device. For example, the resource selection circuit 1144 may be used in conjunction with the above in conjunction with Fig.11 The communication and processing circuit 1141 and the transceiver 1110 shown and described can receive the SCI from the second wireless communication device and decode the SCI to determine the content of the SCI (e.g., reservation information and message information). In some examples, the first transmission and at least one retransmission can utilize a vehicle-to-everything (V2X) radio access technology (RAT).

[0182] In some examples, the first transmission may utilize a vehicle-to-everything (V2X) radio access technology (RAT). In some examples, at least one retransmission may utilize a V2X radio RAT.

[0183] At block 1208, the first wireless communication device may decode feedback associated with the first transmission when the signal strength is greater than the threshold (e.g., if, as a result, etc.), or refrain from detecting feedback when the signal strength is less than the threshold (e.g., if, as a result, etc.). Fig.11The communication and processing circuitry 1141 and transceiver 1110 shown and described may determine whether to detect feedback from at least one third wireless communication device (e.g., a multicast transmission of a second wireless communication device) based on a comparison of the signal strength measured at block 1204 with a threshold. In the event that the signal strength is greater than the threshold, the dynamic detection circuitry 1143 in conjunction with the communication and processing circuitry 1141 and transceiver 1110 may monitor the feedback in the feedback channel. In the event that the signal strength is less than the threshold, the dynamic detection circuitry 1143 may skip monitoring the feedback channel.

[0184] In some examples, the method may further include generating a candidate set of idle resources from the plurality of resources. In some examples, generating the candidate set of idle resources may include including at least one third resource overlapping with at least one second resource in the candidate set of idle resources. In some examples, the at least one third resource is used for communication with the first wireless communication device. In some examples, generating the candidate set of idle resources may include detecting feedback associated with the first transmission, and after detecting the feedback associated with the first transmission, including at least one third resource overlapping with at least one second resource in the candidate set of idle resources.

[0185] In some examples, the method may further include determining that the signal strength is less than or equal to a threshold. In some examples, the method may further include, after determining that the signal strength is less than or equal to the threshold, including at least one third resource overlapping with the at least one second resource in a candidate set of idle resources in the plurality of resources. In some examples, the method may further include avoiding detection feedback after determining that the signal strength is less than or equal to the threshold.

[0186] In some examples, the method may further include determining that the signal strength is greater than or equal to a threshold, and decoding the feedback after determining that the signal strength is greater than or equal to the threshold.

[0187] In some examples, the method may also include determining that the second wireless communication device will not perform at least one retransmission based on decoding of the feedback. In some examples, the method may also include, after determining that the second wireless communication device will not perform at least one retransmission based on decoding of the feedback, including at least one third resource overlapping with at least one second resource in a candidate set of idle resources in the plurality of resources. In some examples, determining that the second wireless communication device will not perform at least one retransmission based on decoding of the feedback may include determining that the first transmission is a first type of multicast transmission associated with the communication range and determining that none of the at least one third wireless communication devices has sent a negative acknowledgement. In some examples, determining that the second wireless communication device will not perform at least one retransmission based on decoding of the feedback may include determining that the first transmission is a second type of multicast transmission associated with the communication range and determining that each of the at least one third wireless communication devices has sent a positive acknowledgement.

[0188] In some examples, the method may further include comparing the signal strength to a threshold. In some examples, the method may further include detecting feedback after comparing the signal strength to the threshold.

[0189] In some examples, the method may further include determining a candidate set of idle resources. In some examples, determining the candidate set of idle resources may include selecting at least one resource that overlaps with at least one second resource used for communication with the first wireless communication device. In some examples, determining the candidate set of idle resources may include detecting feedback associated with the first transmission, and determining whether to include at least one resource overlapping with the at least one second resource in the candidate set of idle resources after detecting the feedback associated with the first transmission.

[0190] In some examples, the method may further include determining that the signal strength is less than or equal to a threshold. In some examples, the method may further include, after determining that the signal strength is less than or equal to the threshold, including at least one resource overlapping with the at least one second resource in a candidate set of idle resources. In some examples, the method may further include selecting not to detect feedback after determining that the signal strength is less than or equal to the threshold. In some examples, the signal strength may include a reference signal received power (RSRP).

[0191] In some examples, the method may further include determining that the signal strength is greater than or equal to a threshold. In some examples, decoding the feedback may include decoding the feedback after determining that the signal strength is greater than or equal to the threshold.

[0192] In some examples, the method may further include determining whether the second wireless communication device will perform at least one retransmission based on decoding of the feedback. In some examples, the method may further include determining whether at least one resource overlapping with at least one second resource is included in the candidate set of idle resources after determining whether the second wireless communication device will perform at least one retransmission based on decoding of the feedback.

[0193] In some examples, determining whether the second wireless communication device will perform at least one retransmission based on decoding of the feedback may include determining that the first transmission may include a first type of multicast transmission associated with the communication range and determining whether a negative acknowledgement was sent by any of the at least one third wireless communication device. In some examples, determining whether the second wireless communication device will perform at least one retransmission based on decoding of the feedback may include determining that the first transmission may include a second type of multicast transmission associated with the communication range and determining whether each of the at least one third wireless communication device sent a positive acknowledgement.

[0194] In some examples, the method may further include determining whether to detect feedback based on signal strength. In some examples, the method may also include determining whether to detect a physical side link feedback channel (PSFCH) based on signal strength. In some examples, the signal strength may include a reference signal received power (RSRP).

[0195] In some examples, determining whether to detect feedback based on signal strength may include comparing the signal strength to a threshold. In some examples, the threshold may be higher than a signal strength threshold defined for resource exclusion. In some examples, the method may further include defining a threshold based on a traffic load associated with a plurality of resources. In some examples, the method may further include defining a threshold based on a channel occupancy rate (CBR) associated with a plurality of resources. In some examples, the method may further include defining a threshold so that a defined percentage of resources in the plurality of resources are included in a candidate set of idle resources.

[0196] Fig.13 1 is a flow chart of a method 1300 for a wireless communication device to determine whether to detect feedback according to some aspects. As described below, in certain implementations within the scope of the present disclosure, some or all of the illustrated features may be omitted, and some of the illustrated features may not be necessary for all example implementations. In some examples, the method 1300 may be performed by the wireless communication device 1100, a processor or processing system, or any suitable component for performing the functions described above and as described below. Fig.11 shown.

[0197] At block 1302, the first wireless communication device may receive a signal from the second wireless communication device. In some examples, receiving the signal from the second wireless communication device may include receiving the signal via a physical sidelink control channel (PSCCH) or a physical sidelink shared channel (PSSCH). Fig.11 The communication and processing circuitry 1141 and transceiver 1110 shown and described may monitor at least one of PSCCH signaling, PSSCH signaling, other signaling, or a combination thereof from a second wireless communication device.

[0198] At block 1304, the first wireless communication device may measure the signal strength of the signal. Fig.11 The signal processing circuit 1142 and / or the communication and processing circuit 1141 shown and described may process the signal received at block 1302 to determine a received signal strength of the signal. In some examples, the signal strength is RSRP.

[0199] At block 1306, the first wireless communication device may receive control information (e.g., sidelink control information) indicating that the second wireless communication device has reserved a first resource of the plurality of resources for a first transmission to at least one third wireless communication device and has reserved at least one second resource of the plurality of resources for at least one retransmission to at least one third wireless communication device. Fig.11 The resource selection circuit 1144 shown and described together with the communication and processing circuit 1141 and the transceiver 1110 can receive the SCI from the second wireless communication device and decode the SCI to determine the content of the SCI (e.g., reservation information and message information). In some examples, the first transmission and at least one retransmission can utilize a vehicle-to-everything (V2X) radio access technology (RAT).

[0200] At block 1308, the first wireless communication device may determine whether to detect feedback associated with the first transmission based on the signal strength. Fig.11 The dynamic detection circuit 1143 in conjunction with the communication and processing circuit 1141 and the transceiver 1110 shown and described may determine whether to detect feedback from at least one third wireless communication device (eg, for a multicast transmission of a second wireless communication device).

[0201] In some examples, feedback detection may include detecting a feedback channel. For example, determining whether to detect feedback based on signal strength may include determining whether to detect a physical sidelink feedback channel (PSFCH) based on signal strength.

[0202] In some examples, determining whether to detect feedback based on signal strength may include determining that the signal strength is less than or equal to a threshold and selecting not to detect feedback after determining that the signal strength is less than or equal to the threshold. For example, selecting not to detect feedback may be based on whether the signal strength is less than or equal to the threshold. In some examples, method 1300 may include including at least one resource overlapping with at least one second resource in a candidate set of idle resources after determining that the signal strength is less than or equal to the threshold. For example, the above combination Fig.11 The resource selection circuitry 1144 shown and described may select resources for the candidate set. In some examples, the decision to schedule a communication may be based on whether the signal strength is less than or equal to a threshold.

[0203] In some examples, determining whether to detect feedback based on signal strength may include determining that the signal strength is greater than or equal to a threshold, and decoding the feedback after determining that the signal strength is greater than or equal to the threshold. For example, the decision whether to detect feedback may be based on whether the signal strength is greater than or equal to the threshold. In some examples, method 1300 may include determining whether the second wireless communication device will perform at least one retransmission based on decoding of the feedback and determining whether at least one resource overlapping with at least one second resource is included in the candidate set of idle resources after determining whether the second wireless communication device will perform at least one retransmission based on decoding of the feedback. For example, the above in combination Fig.11 The resource selection circuit 1144 shown and described together with the communication and processing circuit 1141 and the transceiver 1110 can process the feedback to determine whether there will be a retransmission (e.g., based on the presence and / or absence of NACK and / or ACK), and accordingly determine whether to reclaim at least one second resource. In some examples, the decision whether to select a resource for the candidate set can be based on whether the second wireless communication device will perform at least one retransmission. In some examples, determining whether the second wireless communication device will perform at least one retransmission based on the decoding of the feedback can include determining that the first transmission can include a first type of multicast transmission associated with the communication range and determining whether the negative acknowledgement is sent by any of the at least one third wireless communication device. In some examples, determining whether the second wireless communication device will perform at least one retransmission based on the decoding of the feedback can include determining that the first transmission can include a second type of multicast transmission associated with the communication range and determining whether each of the at least one third wireless communication device has sent a positive acknowledgement. In some examples, determining whether the second wireless communication device will perform at least one retransmission based on the decoding of the feedback can include determining whether there is at least one wireless communication device that sends negative feedback or does not send positive feedback.

[0204] In some examples, determining whether to detect feedback based on signal strength may include comparing the signal strength to a threshold. In some examples, the threshold may be higher than a signal strength threshold defined for resource exclusion (e.g., a threshold for determining whether to reserve a resource from a plurality of resources). In some examples, method 1300 may include defining a threshold based on a traffic load associated with a plurality of resources. In some examples, method 1300 may include defining a threshold based on a channel occupancy rate (CBR) associated with a plurality of resources. In some examples, method 1300 may include defining a threshold such that a defined percentage of a plurality of resources is included in a candidate set of idle resources. In some examples, method 1300 may include defining a threshold such that a defined percentage of a plurality of resources remain idle. For example, in combination with Fig.11 The resource selection circuitry 1144 shown and described may define (eg, generate) the thresholds.

[0205] In some examples, method 1300 may include determining a candidate set of idle resources after determining whether to detect feedback associated with the first transmission based on the signal strength. Fig.11 The resource selection circuit 1146 shown and described may perform a resource selection operation (e.g., determine at least one resource of a candidate set). In some examples, the resource selection operation may be performed based on (e.g., as a result of) a decision to detect feedback. In some examples, determining the candidate set of idle resources may include selecting at least one resource that overlaps with at least one second resource used for communication with the first wireless communication device. In some examples, determining the candidate set of idle resources may include detecting feedback associated with the first transmission and determining whether to include at least one resource overlapping with the at least one second resource in the candidate set of idle resources after detecting the feedback associated with the first transmission. For example, the decision to select a resource may be based on the detected feedback.

[0206] Fig.14 1400 is a flow chart of a method 1400 for a wireless communication device to determine whether to detect feedback according to some aspects. In some examples, one or more aspects of the method 1400 can be combined with Fig.12 Method 1200 and / or Fig.13 As described below, some or all of the features shown may be omitted in certain implementations within the scope of the present disclosure, and some of the features shown may not be necessary for all example implementations. In some examples, method 1400 may be implemented as described above and as Fig.11 The described functions may be performed by the illustrated wireless communication device 1100, a processor or processing system, or any suitable means for performing the described functions.

[0207] At block 1402, the first wireless communication device may determine that the signal strength is less than or equal to a threshold. Fig.11 The signal processing circuitry 1142 and / or the communication and processing circuitry 1141 shown and described may compare the signal strength to a threshold value.

[0208] At block 1404, the first wireless communication device may choose not to detect feedback. For example, based on (eg, as a result of) the determination of block 1402, the above in conjunction with Fig.11 The dynamic detection circuit 1143 shown and described may elect to avoid decoding any feedback sequences on the PSFCH.

[0209] At block 1406, the first wireless communication device may include at least one resource overlapping with at least one second resource in the candidate set of idle resources. Fig.11 The resource selection circuitry 1146 and the communication and processing circuitry 1141 and transceiver 1110 shown and described may update the candidate set based on (e.g., as a result of) the selection of block 1404. The circuitry may then determine whether the first wireless communication device will transmit on at least one resource, and if so, transmit an SCI indicating scheduling of the first wireless communication device for at least one second resource.

[0210] Fig.15 is a flow chart of a method 1500 for a wireless communication device to determine whether to detect feedback according to some aspects. In some examples, one or more aspects of the method 1500 can be combined with Fig.12 Method 1200 and / or Fig.13 As described below, some or all of the features shown may be omitted in certain implementations within the scope of the present disclosure, and some of the features shown may not be necessary for all example implementations. In some examples, method 1500 may be implemented as described above and as Fig.11 The described functions may be performed by the illustrated wireless communication device 1100, a processor or processing system, or any suitable means for performing the described functions.

[0211] At block 1502, the first wireless communication device may determine that the signal strength is greater than or equal to a threshold. Fig.11 The signal processing circuitry 1142 and / or the communication and processing circuitry 1141 shown and described may compare the signal strength to a threshold value.

[0212] At block 1504, the first wireless communication device may decode the feedback based on (e.g., as a result of) determining at block 1502 that the signal strength is greater than or equal to the threshold. Fig.11The dynamic detection circuit 1143 and / or the communication and processing circuit 1141 shown and described can decode the feedback. In some examples, the feedback can be a feedback sequence associated with a multicast message received on the PSFCH. In some examples, the feedback can be decoded based on (e.g., as a result of) a determination that the signal strength is greater than or equal to a threshold.

[0213] At block 1506, the first wireless communication device may determine whether the second wireless communication device will perform at least one retransmission. For example, based on decoding the feedback at block 1504, the above description may be combined with Fig.11 The resource selection circuitry 1146 and the communication and processing circuitry 1141 and transceiver 1110 shown and described may process the feedback to determine whether any NACKs and / or any ACKs were sent in response to the multicast message.

[0214] At block 1508, the first wireless communication device may determine whether at least one resource overlapping with at least one second resource is included in the candidate set of idle resources. For example, based on (e.g., as a result of) the determination at block 1506, the above in conjunction with Fig.11 The resource selection circuit 1146 shown and described in conjunction with the communication and processing circuit 1141 and the transceiver 1110 can determine whether to update the candidate set. For example, if the at least one second resource is idle, the circuit can update the candidate set and, if applicable, send an SCI indicating the scheduling of the at least one second resource by the first wireless communication device. Conversely, if the at least one second resource is not idle, the circuit can search for another resource on which to communicate.

[0215] Fig.16 is a flow chart of a method 1600 for a wireless communication device to determine whether to detect feedback according to some aspects. In some examples, one or more aspects of the method 1600 can be combined with Fig.12 Method 1200 and / or Fig.13 As described below, some or all of the features shown may be omitted in certain implementations within the scope of the present disclosure, and some of the features shown may not be necessary for implementations of all examples. In some examples, method 1600 may be implemented as described above and as Fig.11 The described functions may be performed by the illustrated wireless communication device 1100, a processor or processing system, or any suitable means for performing the described functions.

[0216] At block 1602, the first wireless communication device may determine whether to detect feedback associated with a first transmission based on signal strength. Fig.11The signal processing circuitry 1142 and / or the communication and processing circuitry 1141 shown and described may compare the measured signal strength to a signal strength threshold.

[0217] At block 1604, the first wireless communication device may determine a candidate set of idle resources. Fig.11 The dynamic detection circuitry 1143 and / or the communication and processing circuitry 1141 shown and described may include one or more resources in the candidate set that overlap with resources that will not be used by the second wireless communication device.

[0218] At block 1606, the first wireless communication device may select at least one resource from the candidate set. Fig.11 The resource selection circuit 1146 is shown and described as being operable to randomly select a resource from a candidate set of free resources for transmission by the first wireless communication device.

[0219] At block 1608, the first wireless communication device may transmit the packet via the at least one resource selected at block 1606. Fig.11 The communication and processing circuitry 1141 and transceiver 1110 shown and described may transmit the packet to another wireless communication device on the at least one resource selected at block 1606 .

[0220] Fig.17 1700 is a flow chart of a method 1700 for a wireless communication device to determine whether to detect feedback according to some aspects. In some examples, one or more aspects of the method 1700 can be combined with Fig.12 Method 1200 and / or Fig.13 As described below, some or all of the features shown may be omitted in certain implementations within the scope of the present disclosure, and some of the features shown may not be necessary for implementations of all examples. In some examples, method 1700 may be implemented as described above and as Fig.11 The described functions may be performed by the illustrated wireless communication device 1100, a processor or processing system, or any suitable means for performing the described functions.

[0221] At block 1702, the first wireless communication device may decode the feedback. Fig.11 The signal processing circuit 1142 and the communication and processing circuit 1141 and transceiver 1110 shown and described can monitor the feedback channel (e.g., PSFCH). In addition, the signal processing circuit 1142 can process any signaling received on the channel to recover the feedback information sent by at least one third wireless communication device on the feedback channel.

[0222] At block 1704, the first wireless communication device may determine that the first transmission is a first type of multicast transmission associated with the communication range (e.g., option 1 multicast). Fig.11 The dynamic detection circuit 1143 shown and described in conjunction with the communication and processing circuit 1141 and the transceiver 1110 can determine the type of multicast scheduled by the SCI received from the second wireless communication device. In some examples, the second wireless communication device can indicate the type of multicast in control information sent by the second wireless communication device (e.g., on the PSCCH).

[0223] At block 1706, the first wireless communication device may determine whether a negative acknowledgement was sent by any of the at least one third wireless communication device. Fig.11 The motion detection circuit 1143 shown and described may determine whether any feedback decoded at block 1702 constitutes a NACK.

[0224] Fig.18 1800 is a flow chart of a method 1800 for a wireless communication device to determine whether to detect feedback according to some aspects. In some examples, one or more aspects of the method 1800 may be combined with Fig.12 Method 1200 and / or Fig.13 As described below, some or all of the features shown may be omitted in certain implementations within the scope of the present disclosure, and some of the features shown may not be necessary for all example implementations. In some examples, method 1800 may be implemented as described above and as Fig.11 The described functions may be performed by the illustrated wireless communication device 1100, a processor or processing system, or any suitable means for performing the described functions.

[0225] At block 1802, the first wireless communication device may decode the feedback. Fig.11 The signal processing circuit 1142 and the communication and processing circuit 1141 and transceiver 1110 shown and described can monitor the feedback channel (e.g., PSFCH). In addition, the signal processing circuit 1142 can process any signaling received on the channel to recover the feedback information sent by at least one third wireless communication device on the feedback channel.

[0226] At block 1804, the first wireless communication device may determine that the first transmission is a second type of multicast transmission associated with the communication range (e.g., option 2 multicast). Fig.11The dynamic detection circuit 1143 shown and described in conjunction with the communication and processing circuit 1141 and the transceiver 1110 can determine the type of multicast scheduled by the SCI received from the second wireless communication device. In some examples, the second wireless communication device can indicate the type of multicast in the control information sent by the second wireless communication device (e.g., on the PSCCH).

[0227] At block 1806, the first wireless communication device may determine whether each of the at least one third wireless communication device has sent a positive acknowledgement. Fig.11 The dynamic detection circuit 1143 shown and described may determine whether all feedback decoded at block 1802 constitutes an ACK.

[0228] A summary of several aspects of the disclosure is provided below.

[0229] Aspect 1: A method for wireless communication at a first wireless communication device, the method comprising: receiving a signal from a second wireless communication device; measuring the signal strength of the signal; receiving control information indicating that the second wireless communication device has reserved a first resource among multiple resources for a first transmission to at least one third wireless communication device, and has reserved at least one second resource among the multiple resources for at least one retransmission to the at least one third wireless communication device; and when the signal strength is greater than a threshold, decoding feedback associated with the first transmission, or when the signal strength is less than the threshold, avoiding detecting feedback.

[0230] Aspect 2: The method of Aspect 1 further includes: generating a candidate set of idle resources from a plurality of resources.

[0231] Aspect 3: The method of Aspect 2, wherein generating a candidate set of idle resources comprises: including at least one third resource overlapping with at least one second resource in the candidate set of idle resources, wherein the at least one third resource is used for communication of the first wireless communication device.

[0232] Aspect 4: A method according to any one of Aspects 2 to 3, wherein generating a candidate set of idle resources comprises: detecting feedback associated with a first transmission; and after detecting the feedback associated with the first transmission, including at least one third resource overlapping with at least one second resource in the candidate set of idle resources.

[0233] Aspect 5: The method of any one of Aspects 1 to 4 further includes: determining that the signal strength is less than or equal to a threshold; and after determining that the signal strength is less than or equal to the threshold, including at least one third resource overlapping with at least one second resource in a candidate set of idle resources among multiple resources.

[0234] Aspect 6: The method of Aspect 5 further includes: after determining that the signal strength is less than or equal to a threshold, avoiding detecting feedback.

[0235] Aspect 7: The method of any one of Aspects 1 to 6, wherein the signal strength comprises a reference signal received power (RSRP).

[0236] Aspect 8: The method of any one of Aspects 1 to 7, further comprising: determining that the signal strength is greater than or equal to a threshold; and decoding the feedback after determining that the signal strength is greater than or equal to the threshold.

[0237] Aspect 9: The method of Aspect 8 also includes: determining that the second wireless communication device will not perform at least one retransmission based on decoding of feedback; and after determining that the second wireless communication device will not perform at least one retransmission based on decoding of feedback, including at least one third resource overlapping with at least one second resource in a candidate set of idle resources among multiple resources.

[0238] Aspect 10: The method of Aspect 9, wherein determining based on feedback decoding that the second wireless communication device will not perform at least one retransmission includes: determining that the first transmission includes a first type of multicast transmission associated with a communication range; and determining that at least one third wireless communication device has not sent a negative acknowledgment.

[0239] Aspect 11: A method of any of Aspects 9 to 10, wherein determining whether a second wireless communication device will not perform at least one retransmission based on decoding of feedback includes: determining that the first transmission includes a second type of multicast transmission associated with a communication range; and determining that each of at least one third wireless communication device has sent a positive confirmation.

[0240] Aspect 12: The method of any one of Aspects 1 to 11, further comprising: comparing the signal strength with a threshold.

[0241] Aspect 13: The method of Aspect 12, further comprising: detecting feedback after comparing the signal strength with the threshold.

[0242] Aspect 14: The method of any one of Aspects 1 to 13, wherein receiving the signal from the second wireless communication device comprises: receiving the signal via a physical sidelink control channel (PSCCH) or a physical sidelink shared channel (PSSCH).

[0243] Aspect 15: The method of Aspect 1, wherein the threshold is higher than a signal strength threshold defined for resource exclusion.

[0244] Aspect 16: The method of any one of Aspects 1 to 15, further comprising: defining a threshold based on traffic loads associated with a plurality of resources.

[0245] Aspect 17: The method of any one of Aspects 1 to 16, further comprising: defining a threshold based on a channel occupancy rate (CBR) associated with a plurality of resources.

[0246] Aspect 18: The method of any one of Aspects 1 to 17, further comprising: defining a threshold value so that a defined percentage of resources among the plurality of resources are included in the candidate set of idle resources among the plurality of resources.

[0247] Aspect 19: The method of any one of Aspects 1 to 18 further includes: when the signal strength is greater than a threshold, detecting a physical sidelink feedback channel (PSFCH).

[0248] Aspect 20: The method of any one of Aspects 1 to 19, further comprising: receiving a signal via a physical sidelink control channel (PSCCH) or a physical sidelink shared channel (PSSCH).

[0249] Aspect 21: The method of any one of Aspects 1 to 20, wherein the first transmission and the at least one retransmission utilize a vehicle-to-everything (V2X) radio access technology (RAT).

[0250] Aspect 22: A wireless communication device comprising: a transceiver configured to communicate with a radio access network, a memory, and a processor communicatively coupled to the transceiver and the memory, wherein the processor and the memory are configured to perform any one of aspects 1 to 21.

[0251] Aspect 23: An apparatus configured for wireless communication, comprising at least one component for performing any one of aspects 1 to 21.

[0252] Aspect 24: A non-transitory computer-readable medium storing computer-executable code, comprising code for causing an apparatus to perform any one of aspects 1 to 21.

[0253] Several aspects of a wireless communication network have been described with reference to example implementations. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures, and communication standards.

[0254] For example, various aspects may be implemented in other systems defined by 3GPP, such as Long Term Evolution (LTE), Evolved Packet System (EPS), Universal Mobile Telecommunications System (UMTS), and / or Global System for Mobile Communications (GSM). Various aspects may also be extended to systems defined by the Third Generation Partnership Project 2 (3GPP2), such as CDMA2000 and / or Evolution-Data Optimized (EV-DO). Other examples may be implemented in systems employing IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and / or other suitable systems. The actual telecommunication standard, network architecture, and / or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.

[0255] In this disclosure, the word "exemplary" is used to mean "serving as an example, instance, or illustration." Any implementation or aspect described herein as "exemplary" is not necessarily to be construed as being preferred or advantageous over other aspects of the disclosure. Likewise, the term "aspect" does not require that all aspects of the disclosure include the discussed features, advantages, or modes of operation. The term "coupling" as used herein refers to a direct or indirect coupling between two objects. For example, if object A physically contacts object B, and object B contacts object C, then objects A and C can still be considered to be coupled to each other - even if they are not in direct physical contact with each other. For example, a first object can be coupled to a second object even if the first object has never been in direct physical contact with the second object. The terms "circuit" and "circuitry" are used broadly and are intended to include hardware implementations of electrical devices and conductors that, when connected and configured, implement the performance of the functions described in this disclosure, without limitation to types of electronic circuits, as well as software implementations of information and instructions that, when executed by a processor, implement the performance of the functions described in this disclosure.

[0256] Figure 1 – Fig.18 One or more components, steps, features and / or functions shown in the drawings can be rearranged and / or combined into a single component, step, feature or function, or embodied in several components, steps or functions. Additional elements, components, steps and / or functions can also be added without departing from the novel features disclosed herein. Figure 1 , Figure 3 , Figure 7 , Figure 8 , Fig. 9 and Fig.11 The devices, apparatuses and / or components shown in the can be configured to perform one or more methods, features or steps described herein. The novel algorithms described herein can also be effectively implemented in software and / or embedded in hardware.

[0257] It should be understood that the specific order or hierarchy of steps in the disclosed methods is an illustration of an example process. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in an example order, and are not meant to be limited to the specific order or hierarchy presented unless specifically stated therein.

[0258] The foregoing description is provided to enable those skilled in the art to practice the various aspects described herein. Those skilled in the art will readily appreciate the various modifications to these aspects, and the general principles defined herein may be applicable to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but to conform to the full scope consistent with the language of the claims, wherein, unless otherwise stated, the elements in the singular form are not intended to mean "one and only one", but "one or more". Unless otherwise specified, the term "some" refers to one or more. The phrase "at least one" of a series of items refers to any combination of these items, including a single member. For example, "at least one of a, b, or c" is intended to cover a; b; c; a and b; a and c; b and c; and a, b, and c. All structural and functional equivalents of the elements of the various aspects described in this disclosure that 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 included in the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims.

Claims

1. A method for wireless communication at a first wireless communication device, the method comprising: receiving a signal from a second wireless communication device; Measuring the signal strength of a signal; receiving control information indicating that the second wireless communication device reserves a first resource of a plurality of resources for a first transmission to at least one third wireless communication device and reserves at least one second resource of a plurality of resources for at least one retransmission to the at least one third wireless communication device; as well as When the signal strength is greater than a threshold, a physical sidelink feedback channel PSFCH is detected and feedback associated with the first transmission is decoded, or when the signal strength is less than a threshold, the detection of the PSFCH is avoided.

2. The method according to claim 1, further comprising: A candidate set of idle resources from among a plurality of resources is generated.

3. The method according to claim 2, wherein generating a candidate set of idle resources comprises: The candidate set of idle resources includes at least one third resource overlapping with the at least one second resource, wherein the at least one third resource is used for communication with the first wireless communication device.

4. The method according to claim 2, wherein generating a candidate set of idle resources comprises: detecting feedback associated with the first transmission; as well as After detecting feedback associated with the first transmission, at least one third resource overlapping with at least one second resource is included in the candidate set of free resources.

5. The method according to claim 1, further comprising: Determining that the signal strength is less than or equal to a threshold; as well as After determining that the signal strength is less than or equal to a threshold, at least one third resource overlapping with the at least one second resource is included in a candidate set of idle resources among the plurality of resources.

6. The method according to claim 5, further comprising: After determining that the signal strength is less than or equal to the threshold, detecting the PSFCH is avoided. The method according to claim 1 , wherein the signal strength comprises a reference signal received power (RSRP).

8. The method according to claim 1, further comprising: Determining that the signal strength is greater than or equal to a threshold; and After determining that the signal strength is greater than or equal to the threshold, feedback is decoded.

9. The method according to claim 8, further comprising: determining based on decoding the feedback that the second wireless communication device will not perform at least one retransmission; as well as After determining based on decoding the feedback that the second wireless communication device will not perform at least one retransmission, at least one third resource overlapping with the at least one second resource is included in a candidate set of idle resources among the plurality of resources.

10. The method of claim 9, wherein determining based on decoding the feedback that the second wireless communication device will not perform at least one retransmission comprises: determining that the first transmission comprises a first type of multicast transmission associated with a communication range; as well as It is determined that none of the at least one third wireless communication devices has sent a negative acknowledgement.

11. The method of claim 9, wherein determining whether the second wireless communication device will not perform at least one retransmission based on decoding the feedback comprises: determining that the first transmission comprises a second type of multicast transmission associated with the communication range; as well as A determination is made that each of the at least one third wireless communication devices transmitted a positive acknowledgement.

12. The method according to claim 1, further comprising: The signal strength is compared to a threshold value.

13. The method according to claim 12, further comprising: The PSFCH is detected after comparing the signal strength with a threshold.

14. The method of claim 1 , wherein receiving a signal from a second wireless communication device comprises: The signal is received via the physical sidelink control channel PSCCH or the physical sidelink shared channel PSSCH.

15. A first wireless communication device, comprising: Transceiver; Memory; as well as a processor communicatively coupled to the transceiver and to a memory, wherein the processor and the memory are configured to: receiving a signal from a second wireless communication device via the transceiver; Measuring the signal strength of a signal; receiving, via the transceiver, control information indicating that the second wireless communication device reserves a first resource of a plurality of resources for a first transmission to at least one third wireless communication device and reserves at least one second resource of the plurality of resources for at least one retransmission to the at least one third wireless communication device; and When the signal strength is greater than a threshold, a physical sidelink feedback channel PSFCH is detected and feedback associated with the first transmission is decoded, or when the signal strength is less than a threshold, the detection of the PSFCH is avoided.

16. The first wireless communication device of claim 15, wherein the processor and the memory are further configured to: A candidate set of idle resources from among a plurality of resources is generated.

17. The first wireless communication device of claim 16, wherein the processor and the memory are further configured to: At least one third resource overlapping with at least one second resource is included in the candidate set of idle resources, wherein the at least one third resource is used for communication with the first wireless communication device.

18. The first wireless communication device of claim 16, wherein the processor and the memory are further configured to: detecting feedback associated with the first transmission; and After detecting feedback associated with the first transmission, at least one third resource overlapping with the at least one second resource is included in a candidate set of free resources among the plurality of resources.

19. The first wireless communication device of claim 15, wherein the processor and the memory are further configured to: The signal strength is compared to a threshold value.

20. The first wireless communication device of claim 19, wherein the processor and the memory are further configured to: The PSFCH is detected after comparing the signal strength with a threshold.

21. The first wireless communication device of claim 19, wherein the signal strength comprises a reference signal received power (RSRP).

22. The first wireless communication device of claim 15, wherein the threshold is higher than a signal strength threshold defined for resource exclusion.

23. The first wireless communication device of claim 15, wherein the processor and the memory are further configured to: The threshold is defined based on a traffic load associated with a plurality of resources.

24. The first wireless communication device of claim 15, wherein the processor and the memory are further configured to: The threshold is defined based on a channel occupancy rate CBR associated with the plurality of resources.

25. The first wireless communication device of claim 15, wherein the processor and the memory are further configured to: A threshold is defined such that a defined percentage of the plurality of resources are included in a candidate set of idle resources among the plurality of resources.

26. The first wireless communication device of claim 15, wherein the processor and the memory are further configured to: The signal is received through the physical sidelink control channel PSCCH or the physical sidelink shared channel PSSCH.

27. The first wireless communication device of claim 15, wherein the first transmission and the at least one retransmission utilize a Vehicle-to-Everything (V2X) radio access technology (RAT).

28. A first wireless communication device, comprising: means for receiving a signal from a second wireless communication device; A component for measuring the signal strength of a signal; means for receiving control information indicating that the second wireless communication device has reserved a first resource of the plurality of resources for a first transmission to at least one third wireless communication device and has reserved at least one second resource of the plurality of resources for at least one retransmission to the at least one third wireless communication device; as well as Means for detecting a physical sidelink feedback channel (PSFCH) and decoding feedback associated with a first transmission when the signal strength is greater than a threshold or avoiding detecting the PSFCH when the signal strength is less than a threshold.

29. A non-transitory computer-readable medium having stored thereon instructions executable by one or more processors of a first wireless communication device to: receiving a signal from a second wireless communication device; Measuring the signal strength of a signal; receiving control information indicating that the second wireless communication device has reserved a first resource of the plurality of resources for a first transmission to at least one third wireless communication device and has reserved at least one second resource of the plurality of resources for at least one retransmission to the at least one third wireless communication device; and When the signal strength is greater than a threshold, a physical sidelink feedback channel PSFCH is detected and feedback associated with the first transmission is decoded, or when the signal strength is less than a threshold, the detection of the PSFCH is avoided.

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