Adaptive sensing based on retransmission times

Abstract

The device receives an indication of resources reserved for the second UE in a transmission from the second UE. The device measures a received power of the transmission from the second UE. The device excludes the reserved resources indicated by the second UE from the set of candidate resources based on the received power of the transmission from the second UE satisfying a threshold, wherein the threshold is based at least in part on whether the reserved resources are associated with a retransmission.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to provisional application serial number 62 / 980860, filed on February 24, 2020, entitled “Adaptive Sensing Based on Number of Retransmissions,” and U.S. patent application serial number 17 / 152578, filed on January 19, 2021, entitled “ADAPTIVE SENSING BASED ON NUMBER OF RETRANSMISSIONS,” both of which are expressly incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates generally to communication systems and, more particularly, to sidelink communications. Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies that can support communications with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at municipal, national, regional and even global levels. An example communication standard is 5G New Radio (NR). 5GNR is part of the continuous mobile broadband evolution released by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC) and ultra-reliable low latency communication (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. Various aspects of wireless communication may include direct communication between devices, such as V2X, V2V and / or other D2D communications. There is a need for further improvements to V2X, V2V and / or other D2D technologies. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0006] A simplified summary of one or more aspects is presented below to provide a basic understanding of these aspects. This summary is not an extensive overview of all contemplated aspects, and is neither intended to identify important or critical elements of all aspects, nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that is presented later.

[0007] In one aspect of the present disclosure, a method, computer-readable medium, and apparatus for wireless communication at a first user equipment (UE) are provided. The apparatus receives an indication of resources reserved for a second UE in a transmission from the second UE. The apparatus measures a received power of the transmission from the second UE. The apparatus excludes the reserved resources indicated by the second UE from a set of candidate resources based on the received power of the transmission from the second UE satisfying a threshold, wherein the threshold is based at least in part on whether the reserved resources are associated with a retransmission.

[0008] To achieve the foregoing and related ends, one or more aspects include features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features represent only a few of the various ways in which the principles of the various aspects can be employed, and the present description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0010] Figure 2 Example aspects of a sidelink timeslot structure are illustrated.

[0011] Figure 3 is a diagram illustrating an example of a first device and a second device involved in wireless communication based on, for example, sidelink communication.

[0012] Figure 4 is a diagram illustrating example resource allocation and reservation.

[0013] Figure 5 is a diagram illustrating an example timeline for sensing-based resource selection.

[0014] Figure 6 An example of wireless communication between devices based on sidelink communication is illustrated.

[0015] Figure 7 is an example communication flow between a first UE and a second UE according to aspects of the present disclosure.

[0016] Figure 8is a flow chart of a wireless communication method at a UE according to aspects of the present disclosure.

[0017] Fig. 9 is a diagram illustrating an example of a hardware implementation for an example apparatus. DETAILED DESCRIPTION

[0018] 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 configuration 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 is apparent to those skilled in the art that these concepts may be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid confusing such concepts.

[0019] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0020] For example, an element or any part of an element or any combination of elements can be implemented using a "processing system" including one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on chip (SoCs), baseband processors, 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. One or more processors in a processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes, functions, etc.

[0021] Therefore, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, these functions may be stored on a computer-readable medium as one or more instructions or codes or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media may be any available medium accessible to a computer. As an example and not limitation, such a computer-readable medium may include a random access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), an optical disk storage, a magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the above types, or any other medium that may be used to store computer executable code in the form of computer-accessible instructions or data structures.

[0022] In a distributed resource allocation mode, a UE may send data using sidelink resources selected by the UE based on a sensing mechanism. As part of the sensing mechanism, the UE may monitor sidelink resource reservations in order to determine (e.g., sense) sidelink resources reserved by (multiple) other UEs. The UE may select sidelink transmission resources that are not reserved by other sidelink UEs. In some examples, the UE may also determine to use or reuse resources already reserved by other (multiple) sidelink UEs, such as when the data to be sent by the sidelink UE (e.g., PSSCH) has a higher priority. Sometimes, when multiple sidelink UEs are using the same sidelink (e.g., frequency and time) resources to send data, this may result in resource conflicts (e.g., interference).

[0023] Various aspects presented herein may enable sidelink UEs to reuse / reclaim reserved resources in a more efficient manner by using (multiple) reserved resources that are less likely to be used by the UEs for which they were reserved. As presented herein, UEs may apply different thresholds to resources reserved for initial transmissions and resources reserved for retransmissions. Various aspects presented herein may help increase sidelink resource usage while avoiding resource waste and / or resource conflicts.

[0024] Figure 11 is a diagram illustrating an example of a wireless communication system and access network 100. In one aspect of the present disclosure, a first UE (e.g., UE 104) may determine whether to use a reserved resource based at least in part on the number of retransmissions associated with the reserved resource and the RSRP of a sidelink message (e.g., SCI) that reserves the resource. In one aspect, the first UE may include a resource sensing, selection, and reservation component 198 configured to receive an indication of the resources reserved for the second UE in a transmission from the second UE. The resource sensing, selection, and reservation component 198 may also be configured to measure the received power of the transmission from the second UE. The resource sensing, selection, and reservation component 198 may also be configured to determine to exclude the reserved resources indicated by the second UE if the received power of the transmission from the second UE meets a threshold, wherein the threshold is based at least in part on whether the reserved resources are associated with retransmissions.

[0025] The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and a core network (e.g., 5GC) 190. The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0026] The link between UE 104 and base station 102 or 180 can be established as an access link, for example, using a Uu interface. Other communications can be exchanged between wireless devices based on the sidelink. For example, some UEs 104 can communicate directly with each other using a device-to-device (D2D) communication link 158. In some examples, the D2D communication link 158 can use the DL / UL WWAN spectrum. The D2D communication link 158 can use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communications can be through various wireless D2D communication systems, for example, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE or NR.

[0027] Some examples of sidelink communications may include a vehicle-based communication device that may communicate and / or communicate with other devices based on vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from a vehicle-based communication device to a road infrastructure node such as a roadside unit (RSU)), vehicle-to-network (V2N) (e.g., from a vehicle-based communication device to one or more network nodes such as a base station), vehicle-to-pedestrian (V2P), cellular vehicle-to-everything (C-V2X), and / or combinations thereof, which may be collectively referred to as vehicle-to-everything (V2X) communications. Sidelink communications may be based on V2X or other D2D communications such as proximity services (ProSe). In addition to the UE, sidelink communications may also be sent and received by other transmitting and receiving devices such as a road test unit (RSU) 107. Sidelink communications may be exchanged using a PC5 interface, such as in conjunction with Figure 2 Although the following description (including Figure 2 An example time slot structure of the present invention may provide an example of sidelink communications in conjunction with 5G NR, but the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0028] Base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interact with EPC 160 via a backhaul link 132 (e.g., an S1 interface). Base stations 102 configured for NR (collectively referred to as Next Generation RAN (NG-RAN)) may interact with core network 190 via a backhaul link 184. Base stations 102 may perform one or more of the following functions, among other functions: transmission of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, non-access stratum (NAS) message distribution, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and device tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) via a backhaul link 134 (eg, an X2 interface). The backhaul link 134 may be wired or wireless.

[0029] Base station 102 can communicate with UE 104 wirelessly. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' can have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include a home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 can include an uplink (UL) (also called a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also called a forward link) transmission from base station 102 to UE 104. The communication link 120 can use multiple input multiple output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link can be through one or more carriers. The base station 102 / UE 104 may use spectrum (x component carriers) of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) bandwidth per carrier allocated in a carrier aggregation totaling up to Yx MHz for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric for DL ​​and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0030] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

[0031] The small cell 102' may operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may expand the coverage of the access network and / or increase the capacity of the access network.

[0032] The electromagnetic spectrum is often subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified as frequency ranges named FR1 (410MHz–7.125GHz) and FR2 (24.25GHz–52.6GHz). Frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Although a portion of FR1 is greater than 6GHz, FR1 is often referred to (interchangeably) as the “below (sub) 6GHz” band in various documents and articles. A similar naming issue sometimes occurs with FR2, which is often referred to (interchangeably) as the “millimeter wave” band in documents and articles, although it is different from the extremely high frequency (EHF) band (30GHz–300GHz) defined as a “millimeter wave” band by the International Telecommunication Union (ITU).

[0033] In view of the above aspects, unless otherwise explicitly stated, the term "sub-6 GHz" and the like (if used herein) can broadly refer to frequencies that can be less than 6 GHz, can be within FR1, or can include mid-band frequencies. In addition, unless otherwise explicitly stated, "millimeter wave" and the like (if used herein) can broadly refer to frequencies that can include mid-band frequencies, can be within FR2, or can be within the EHF band.

[0034] The base station 102, whether a small cell 102' or a large cell (e.g., a macro base station), can include an eNB, a gNodeB (gNB), or other types of base stations. Some base stations, such as gNB 180, can operate in the traditional 6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies for communicating with UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 can be referred to as a mmW base station. Extremely high frequency (EHF) is a portion of the RF in the electromagnetic spectrum. EHF ranges from 30 GHz to 300 GHz, with wavelengths between 1 mm and 10 mm. Radio waves in this band can be referred to as millimeter waves. Near millimeter waves can extend down to frequencies of 3 GHz with wavelengths of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also known as centimeter waves. Communications using mmV / near mmV radio bands have extremely high path losses and short distances. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0035] The base station 180 may transmit beamformed signals to the UE 104 in one or more transmit directions 182'. The UE 104 may receive beamformed signals from the base station 180 in one or more receive directions 182". The UE 104 may also transmit beamformed signals to the base station 180 in one or more transmit directions. The base station 180 may receive beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180 / UE 104. The transmit and receive directions of the base station 180 may be the same or different. The transmit and receive directions of the UE 104 may be the same or different. Although the example is described with respect to the base station 180 and the UE 104, these aspects may be similarly applied between a first device and a second device (e.g., a first UE and a second UE) for sidelink communication.

[0036] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are transmitted through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts specific services, and may be responsible for session management (start / stop) and collecting charging information related to eMBMS.

[0037] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may communicate with a unified data management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Typically, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0038] Base stations may include and / or be referred to as gNBs, Node Bs, eNBs, access points, base transceiver stations, radio base stations, radio transceivers, transceiver functions, basic service sets (BSSs), extended service sets (ESSs), transmit receive points (TRPs), or some other suitable terminology. Base stations 102 provide access points to EPC 160 or core network 190 for UEs 104. Examples of UEs 104 include cellular phones, smart phones, session initiation protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electronic meters, gas pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or any other similarly functional device. Some of UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, toasters, vehicles, heart monitors, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handheld device, a user agent, a mobile client, a client, or some other suitable terminology.

[0039] Figure 2 Included are diagrams 200 and 210 illustrating example aspects of a time slot structure that may be used for sidelink communications (e.g., between UE 104, RSU 107, etc.). In some examples, the time slot structure may be within a 5G / NR frame structure. In other examples, the time slot structure may be within an LTE frame structure. Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. Figure 2The example time slot structure in is only an example, and other sidelink communications may have different frame structures and / or different channels for sidelink communications. A frame (10ms) can be divided into 10 subframes (1ms) of equal size. Each subframe may include one or more time slots. A subframe may also include a mini time slot, which may include 7, 4 or 2 symbols. Depending on the time slot configuration, each time slot may include 7 or 14 symbols. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. Figure 200 illustrates a single resource block for a single time slot transmission, for example, which may correspond to a 0.5ms transmit time interval (TTI). The physical sidelink control channel may be configured to occupy multiple physical resource blocks (PRBs), for example, 10, 12, 15, 20 or 25 PRBs. PSCCH may be limited to a single subchannel. For example, the PSCCH duration may be configured to be 2 symbols or 3 symbols. For example, a subchannel may include 10, 15, 20, 25, 50, 75, or 100 PRBs. Resources for sidelink transmissions may be selected from a resource pool including one or more subchannels. As a non-limiting example, a resource pool may include 1-27 subchannels. A PSCCH size may be established for a resource pool, for example, between 10-100% of a subchannel, for 2 symbols or 3 symbols. In some examples, the first symbol of a subframe may be a symbol used for automatic gain control (AGC) (e.g., an AGC symbol), and the last symbol may be a symbol used for a transmit / receive switching time. The AGC symbol may be used by the receiving end to adjust the operating point. Figure 2 Figure 210 in illustrates an example where the PSCCH occupies approximately 50% of a subchannel as an example to illustrate the concept of the PSCCH occupying a portion of a subchannel. The physical sidelink shared channel (PSSCH) occupies at least one subchannel. In some examples, the PSCCH may include a first portion of sidelink control information (SCI), and the PSSCH may include a second portion of the SCI.

[0040] A resource grid can be used to represent the frame structure. Each time slot may include a resource block (RB) (also called a physical RB (PRB)) extending 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme. Figure 2 As shown in , some REs may include control information in the PSCCH and some REs may include a demodulation RS (DMRS). At least one symbol may be used for feedback. Figure 2An example is illustrated having two symbols for a physical sidelink feedback channel (PSFCH) with adjacent gap symbols. Symbols before and / or after the feedback can be used for turnaround between data reception and feedback transmission. The gap enables the device to switch from operating as a transmitting device to preparing to operate as a receiving device, for example, in the next time slot. As illustrated, data can be sent in the remaining REs. The data can include the data messages described herein. The location of any of the data, DMRS, SCI, feedback, gap symbols, and / or LBT symbols can be different from Figure 2 In some examples, multiple time slots may be aggregated together.

[0041] Figure 3 300 is a block diagram of a first wireless communication device 310 communicating with a second wireless communication device 350 based on a sidelink. In some examples, the devices 310 and 350 may communicate based on V2X or other D2D communications. The communication may be based on a sidelink using a PC5 interface. The devices 310 and 350 may include UEs, RSUs, base stations, etc. The packet may be provided to a controller / processor 375 that implements layer 3 and layer 2 functions. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer.

[0042] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functions associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transmission channel, forward error correction (FEC) encoding / decoding of the transmission channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation channels of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation points based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols can then be divided into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. Channel estimates may be derived from reference signals and / or channel condition feedback sent by device 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318 (TX). Each transmitter 318 (TX) may modulate an RF carrier with a corresponding spatial stream for transmission.

[0043] At the device 350, each receiver 354 (RX) receives a signal through its respective antenna 352. Each receiver 354 (RX) recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functions associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the device 350. If multiple spatial streams are destined for the device 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier are recovered and demodulated by determining the most likely signal constellation point sent by the device 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by device 310. The data and control signals are then provided to controller / processor 359, which implements layer 3 and layer 2 functionality.

[0044] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. The controller / processor 359 may provide demultiplexing, packet reassembly, decryption, header decompression, and control signal processing between transport channels and logical channels. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0045] Similar to the functions described in conjunction with the transmission of device 310, the controller / processor 359 can provide RRC layer functions associated with system information (e.g., MIB, SIB) acquisition, RRC connection and measurement reporting; PDCP layer functions associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions associated with transmission of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs to TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority processing, and logical channel priority.

[0046] The TX processor 368 may select the appropriate coding and modulation schemes and facilitate spatial processing using channel estimates derived by the channel estimator 358 from a reference signal or feedback sent by the device 310. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354 (TX). Each transmitter 354 (TX) may modulate an RF carrier with a corresponding spatial stream for transmission.

[0047] Transmissions are processed at device 310 in a manner similar to that described in conjunction with the receiver functionality at device 350. Each receiver 318 (RX) receives a signal through its respective antenna 320. Each receiver 318 (RX) recovers information modulated on an RF carrier and provides the information to a RX processor 370.

[0048] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. The controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0049] At least one of the TX processor 368, the RX processor 356, the controller / processor 359, the TX processor 316, the RX processor 370, or the controller / processor 375 may be configured to perform and Figure 1 Various aspects related to the resource sensing, selection and reservation component 198.

[0050] As automakers move toward fully autonomous vehicles, sidelink communications have become increasingly important. A non-limiting example of sidelink communications is V2X. V2X communications can utilize synchronized timing for communication, where V2X users can use the same reference timing. Devices based on V2X or other D2D-based communications can determine radio resource (e.g., subchannels in the frequency domain) utilization to avoid conflicts with other devices.

[0051] Sidelink communications directly exchanged between sidelink UEs (or sidelink devices) may include discovery messages for sidelink UEs to find nearby UEs. Sidelink communications may be based on resource allocation mechanisms of different types or modes. In a first resource allocation mode (which may be referred to as "mode 1" in this article), centralized resource allocation may be provided by a network entity. For example, a base station 102 or 180 may determine resources for sidelink communications and may allocate resources to different UEs 104 for sidelink transmission. In this first mode, the sidelink UE receives an allocation of sidelink resources from a base station 102 or 180. In a second resource allocation mode (which may be referred to as "mode 2" in this article), distributed resource allocation may be provided. In mode 2, each UE may autonomously determine resources for sidelink transmission. In order to coordinate the selection of sidelink resources by each UE, each UE may use sensing technology to monitor resource reservations of other sidelink UEs, and may select resources for sidelink transmission from unreserved resources. Sidelink transmissions and / or resource reservations may be periodic or aperiodic, where the UE may reserve resources for transmission in the current time slot and up to two future time slots (discussed below). These resource allocation mechanisms for sidelink communications may provide power savings, e.g., at the physical layer or the medium access control (MAC) layer. Power savings may be helpful for sidelink applications such as public safety applications, commercial applications, wearable devices, etc., which may include periodic and aperiodic traffic.

[0052] For example, for a sidelink UE that is sending data based on a sensing mechanism or resource allocation mode 2, the sidelink UE may determine (e.g., sense) whether the selected sidelink resource has been reserved by (multiple) other UEs before selecting the sidelink resource for data transmission. If the sidelink UE determines that the sidelink resource has not been reserved by (multiple) other sidelink UEs, the sidelink UE may use the selected sidelink resource to send data. In some examples, the UE may also determine to use or reuse (multiple) resources that have been reserved by another sidelink UE, such as when the data (e.g., PSSCH) to be sent by the sidelink UE has a higher priority. Sometimes, when multiple sidelink UEs are using the same sidelink (e.g., frequency and time) resources to send data, this may result in resource conflicts (e.g., interference).

[0053] A sidelink UE can estimate or determine which radio resources (e.g., sidelink resources) can be used and / or reserved by others by detecting and decoding sidelink control information (SCI) sent by (multiple) other sidelink UEs or stations. The sidelink UE can exclude resources used and / or reserved by other sidelink UEs from a set of candidate resources, and can use unused / unreserved resources in the candidate set for sidelink transmissions (e.g., including SCI and / or data). The number of sidelink resources (e.g., subchannels per subframe) that can be reserved by a sidelink UE can vary depending on the size of the data to be sent by the sidelink UE. Although this example is described for a sidelink UE that receives a reservation from another sidelink UE, a reservation can also be received from an RSU or other device that communicates based on a sidelink.

[0054] Figure 4 4 is a diagram illustrating an example of resource reservation for sidelink transmission in a sidelink resource pool 424. Resource allocations for each UE (e.g., a sidelink device) may include one or more subchannels (SCs) in the frequency domain (e.g., SC1 to SC4) and time slots in the time domain. The UE may use resources in a current time slot to perform data transmission and may reserve resources in future time slots for data retransmission. In one example, as Figure 4 As shown in FIG. 400 , a sidelink UE such as a first UE 420 or a second UE 422 may reserve up to two future time slots for retransmission. Resource reservation may be limited to a window or pool with defined time slots and subchannels. For example, Figure 4As shown in Figure 400, the sidelink resource pool 424 (which may also be referred to as a resource selection window) may include eight (8) time slots multiplied by four (4) subchannel windows, which may provide a total of thirty-two (32) available resource blocks. A first UE 420 (e.g., UE1) may reserve resources 402 including a subchannel (e.g., SC1) in a current time slot (e.g., time slot 1) for data transmission, and may reserve two additional future subchannels and time slots within the sidelink resource pool 424 for data retransmission. For example, the first UE 420 may reserve resources 404 including a subchannel at time slot 3 (e.g., SC 3) and resources 406 including a subchannel at time slot 4 (e.g., SC 2) for future retransmissions, as shown in Figure 400. Figure 4 As shown. Although the example shows the reservation of two additional time slot resources, the reservation may only reserve one additional time slot resource, or may be a reservation of a time slot for initial transmission only without additional reserved resources. After selecting and / or reserving resources for transmission and / or retransmission, the first UE 420 may send its resource reservation information to other UEs such as the second UE 422. For example, the first UE 420 may send its resource reservation information in an SCI, such as using a reserved resource field in the SCI. The SCI may be a first-stage SCI. Similarly, the second UE 422 may reserve resources 408 including two subchannels at time slot 1 (e.g., SC3 and SC4) for its current data transmission, and may reserve resources 410 including two subchannels at time slot 4 (e.g., SC3 and SC4) and resources 412 including two subchannels at time slot 7 (e.g., SC1 and SC2) for retransmission. After selecting and / or reserving resources for transmission and / or retransmission, the second UE 422 may also send its resource reservation information to other UEs such as the first UE 420 via the SCI.

[0055] If a third UE (e.g., UE 3) is to select one or more resources from the sidelink resource pool 424 for data transmission and / or retransmission, the third UE may first decode the SCI within a time period to identify which resources (e.g., candidate resources) are available, such as resources not reserved by other UEs. The third UE may then use the unreserved resources for data transmission. For example, the third UE may receive and decode the SCI sent from the first UE 420 and the second UE 422, and the third UE may determine that resources 402, 404, 406, 408, 410, and 412 within the sidelink resource pool 424 have been used / reserved by the first UE 420 and the second UE 422. In this way, the third UE may exclude these resources from its candidate resources, and the third UE may select other unreserved / unused resources (e.g., available subchannels and time slots) as candidate resources for data transmission and retransmission, which may be based on the number of adjacent subchannels to which the data to be transmitted (e.g., packets) may fit.

[0056] As described above, the sidelink resource reservation may be periodic or aperiodic. If the resource reservation is configured as periodic, the periodic resource reservation may be turned on or off by a configuration in the sidelink resource pool. In addition, the UE may be configured to continuously monitor resource reservation messages (e.g., SCI) sent by other UEs or stations so that the UE may maintain a sensing history of which resources are being used and / or reserved. Then, when the UE has a packet to be transmitted, the UE may perform resource selection based at least in part on the sensing history. The UE may maintain the reservation information for a period of time, for example, within a sensing window (e.g., sensing window 506). The length of the sensing window may be configured for the UE, such as by a base station. Each resource reservation may have a priority indicated in the SCI so that a transmission (e.g., a packet) with a higher priority reservation may preempt a transmission with a lower priority reservation.

[0057] The UE may perform signal / channel measurements on sidelink resources that have been reserved and / or used by (multiple) other UEs, such as by measuring the reference signal received power (RSRP) of a message (e.g., SCI) that reserves the sidelink resources. Based at least in part on the signal / channel measurements, the UE may consider using / reusing sidelink resources that have been reserved by (multiple) other UEs. For example, when the measured RSRP of the message for the reserved resources is below a threshold, the UE may consider the reserved resources to be available, and then the UE may use / reuse the reserved resources for transmission. When the measured RSRP is below a threshold, it may indicate that the UE that reserved the resources may be far away, and the use / reuse of the reserved resources is unlikely to cause interference or impact to the UE. In some examples, the threshold of RSRP may be determined or changed based on the amount of available resources in the resource selection window. For example, if the amount of available resources is below a threshold / percentage (e.g., below 20%) within the resource selection window, the UE may be configured to use an increased / higher RSRP threshold so that the UE is more likely to be able to reuse the reserved resources. In addition, a sidelink (or packet) transmission or retransmission may be configured with a packet delay budget (PDB), which may provide a time for a sidelink transmission or retransmission to be sent by the UE. If the UE is unable to send a sidelink transmission within the PDB, the UE may be configured to abort or discard the transmission and restart the sidelink resource sensing and selection process. Various aspects presented herein may enable the UE to find a balance between excluding reserved resources (e.g., to avoid conflicts with other UEs) and reusing reserved resources (e.g., to increase resource usage), so that the UE may select a sidelink resource that satisfies its transmitted packet delay budget while avoiding resource conflicts.

[0058] Figure 5 is an example of a timeline 500 for sensing-based resource selection. The UE may select a radio resource from a resource selection window 502, which in this example is shown as having sixteen (16) resource blocks formed by two subchannels and eight time slots. The duration of the resource selection window 502 may be represented by [n+T1, n+T2], where n may represent the time when resource selection is triggered, such as shown at 504, when the UE is to select a sidelink resource for transmission. T1 may represent the beginning of the resource selection window 502, and T2 may represent the end of the resource selection window 502. The length of the resource selection window 502 may vary depending on the configuration and may be configured via upper layers (e.g., from 20 ms to 100 ms, etc.). In some examples, the value of T1 may range from zero (0) to the time it takes the UE to process and implement the resource selection (e.g., T proc,1 ), and T2 can be selected from T 2,minIn some examples, T 2,min A configurable priority value for each sidelink can be indicated in the SCI from the following set of values: 1, 5, 10, 20, ..., 2 μ-1 time slots, where μ=1, 2, 3, 4 represent 15, 30, 60, 120 kHz subcarrier spacing (SCS) respectively. The PDB can be used to define an upper limit on the delay experienced by a packet between the UE and the Policy and Charging Enforcement Function (PCEF).

[0059] Since the UE can sense and decode sidelink messages (e.g., SCI) from (multiple) other UEs, the sensing history (or resource usage / reservation history) can be recorded / determined from the sensing window 506 and used by the UE to determine which resources in the resource selection window 502 are reserved by (multiple) other UEs. For example, the sensing window 506 can represent a duration before resource selection during which the UE can collect resource reservation related information from other UEs (e.g., via their SCIs). In one example, the duration can be the last 1000ms before the resource selection is triggered at 504. In other examples, the sensing window 506 can have a duration between 100ms and 1100ms (e.g., Figure 5 ) minus the time it takes the UE to process the sensing window 506 (e.g., T proc,0 ).

[0060] Based on the resource reservation related information obtained during the sensing window 506, the UE may determine available candidate resources for the resource selection window 502. For example, based on the resource reservation information decoded from the SCI of other UEs (e.g., UE1, UE2, and UE3), the UE may find that UE1 has sent data during the sensing window 506, and has reserved resource blocks 508 and 510 for retransmission of the data in the resource selection window 502. Similarly, based on the sensing window 506, the UE may find that resource blocks 512 and 514 have been reserved by UE2 and UE3, respectively, for their retransmissions, as shown in FIG. Figure 5 As shown in . In this way, the UE can determine that resource blocks 508, 510, 512 and 514 in the resource selection window 502 are not available for selection and can exclude these resource blocks from selection. The UE can then identify the remaining resource blocks as available candidate resources. The UE can perform sensing until a defined duration (e.g., T3) before its transmission.

[0061] Sometimes, when the sidelink channel is congested, it may not be easy for the UE to find available resources in the sidelink channel (e.g., within the resource selection window). In some examples, congestion may be caused by the above-mentioned sensing-based (e.g., resource reservation) mechanism when a large number of resources are excluded from candidate resources because they have been reserved for retransmission by other UEs. For example, referring back to Figure 4 , UE 420 may have reserved resources 404 and 406 for retransmission, and UE 422 may have reserved resources 410 and 412 for retransmission. Therefore, these resources may be excluded from resource selection of other UEs. In some examples, the UE that reserves resources may not use the reserved resources. For example, UE 420 may use resource 402 to send a packet, and UE 420 may also reserve resources 404 and 406 for retransmission of the packet. However, if the transmission of the packet using resource 402 is successful, such as when positive feedback (e.g., HARQ ACK) is received for the transmission, UE 420 may determine to skip or abort the retransmission. For example, when the transmission using resource 402 is successful, UE 420 may determine not to use reserved resources 404 and 406. This may cause resources 404 and 406 to be excluded from resource selection of other UEs, and resources 404 and 406 may be wasted because they are not utilized by UE 420 that reserved them. Furthermore, when the sidelink channel is congested, packet collisions are also more likely to occur when multiple UEs attempt to send / retransmit packets through the sidelink channel simultaneously.

[0062] In one aspect of the present disclosure, in order to avoid excessive resource exclusion / waste due to resources being reserved for retransmission but not being used, the UE may be configured to monitor the HARQ feedback of (multiple) other UEs to determine the likelihood that the reserved resources will be used by the (multiple) UEs that reserved the resources. Figure 4, UE 420 may use resource 402 (e.g., at subchannel SC 1 and time slot 1) for data transmission, and UE 420 may reserve resources 404 and 406 (e.g., at subchannel SC 3 and time slot 3, and SC 2 and time slot 4) for data retransmission. After UE 420 transmits data using resource 402, a transmitting UE may monitor whether UE 420 receives a negative acknowledgement (NACK). If UE 420 receives a NACK, the transmitting UE may assume that the data transmission from UE 420 was unsuccessful, and UE 420 may retransmit using reserved resources 404 and / or 406. On the other hand, if UE 420 does not receive a NACK, the transmitting UE may assume / determine that the data transmission from UE 420 using resource 402 was successful, and UE 420 may skip data retransmission using the reserved resources. In this way, the transmitting UE may reclaim / reuse resources (eg, resources 404 and / or 406) reserved by UE 420 for its own use (eg, for its data transmissions). However, monitoring HARQ feedback for transmissions of other UEs may increase the workload of the UE.

[0063] In other examples, the UE may measure the reference signal received power (RSRP) of a sidelink transmission (e.g., SCI in PSCCH and / or PSSCH) from another UE, and the UE may estimate whether one or more reserved resources may be reclaimed for their use based at least in part on the measured RSRP of the sidelink transmission. In some examples, the RSRP may correspond to, for example, a linear average of the power contributions of resource elements carrying signals (such as demodulation reference signals). The power of each resource element may be determined based on the energy received during the useful portion of the symbol (e.g., excluding the cyclic prefix). Thus, when the UE is selecting sidelink resources for transmission, the UE may be configured to exclude resources reserved by sidelink messages (e.g., SCI) having a measured RSRP above a threshold. On the other hand, if the RSRP of the sidelink message of the reserved resources does not exceed the threshold, the UE may not exclude the reserved resources, and the UE may select the reserved resources for its transmission.

[0064] Figure 6600 is a diagram illustrating an example of sidelink wireless communication between devices based on sidelink communication. A non-limiting example of sidelink communication is V2X. Although these aspects are described for a transmitting device and a receiving device to distinguish between the two devices, both devices can be capable of transmitting and receiving. Although the example aspects are described for UEs for the purpose of illustrating concepts, these aspects can also be applied by other sidelink devices, such as roadside units (RSUs), etc. UE602 can send a transmission 614, for example, including a control channel and / or a corresponding data channel that can be received by receiving UEs 604, 606. The control channel can include information for decoding the data channel and can also be used by the receiving device to avoid interference by suppressing transmission on occupied resources during data transmission. The number of transmission time intervals (TTIs) and the RBs that will be occupied by the data transmission can be indicated in a control message from the transmitting device. Each of UEs 602, 604, 606, 608 can also have the ability to operate as a transmitting device in addition to operating as a receiving device. Therefore, UEs 606, 608 are shown as sending transmissions 616 and 620, respectively. The transmissions 614, 616, 620 may be broadcast, multicast, or unicast to nearby devices. For example, a UE 602 may send communications (e.g., data) for reception by other UEs within range 601 of the UE 602. Additionally or alternatively, an RSU 607 may receive communications 618 from and / or send communications 618 to the UEs 602, 606, 608.

[0065] Transmissions 614, 616, 620 and / or communications 618 may be based on a time slot structure. The time slot structure may include a combination of Figure 2 Any aspects described. For example, as shown by time slots 622 and time slots 624, transmissions can be in units of time slots (e.g., start and end symbols with RRC configuration), and each time slot can include 14 symbols (e.g., symbol #0 to symbol #13). The first symbol (e.g., symbol #0) can be a repetition of a second symbol for AGC purposes, so that in some examples the first symbol can also be referred to as an AGC symbol. After the last symbol (e.g., symbol #12), there may be a symbol gap (e.g., symbol #13) to allow the UE to perform time division duplex (TDD) switching. As shown by time slots 622, for time slots where the physical sidelink feedback channel (PSFCH) is not configured (described below in conjunction with Figure 5Discussion), the UE may be configured to use symbols #0 to #12 for physical sidelink control channel (PSCCH)) and / or physical sidelink shared channel (PSSCH) transmission, and symbol #13 may be left as a gap. As shown by time slot 624, for a time slot configured with PSFCH, the UE may be configured to use symbols #0 to #9 for PSCCH / PSSCH transmission, and symbols #11 and #12 for PSFCH transmission, and symbol #13 may be left as a gap.

[0066] Various aspects presented herein may enable a sidelink UE to determine whether to reuse / reclaim (multiple) reserved resources in a more efficient manner, such that the reserved resources that are less likely to be used by the UE that reserved the resources may be reused / reclaimed by the sidelink to reduce resource waste while avoiding resource conflicts. In one aspect of the present disclosure, the sidelink UE may determine whether to use the reserved resources based at least in part on the number of retransmissions associated with the reserved resources and the RSRP of the sidelink message (e.g., SCI) that reserved the reserved resources.

[0067] Figure 7 FIG. 7 is a communication flow 700 illustrating an example of a UE reclaiming reserved resources based on a number of retransmissions associated with the reserved resources according to aspects of the present disclosure. The communication may be based on V2X, V2V, or other D2D-based communication involving direct transmission from a transmitting device to a receiving device. The communication sent from the transmitting device may be broadcast and received by multiple receiving devices within the transmission range of the transmitting device, such as in conjunction with Figure 6 Optional aspects may be shown with dashed lines.

[0068] At 706, the first UE 702 may receive an indication 720 from the second UE 704, where the indication 720 may indicate one or more resources reserved in the sidelink channel for the UE 704, such as within a resource selection window for the sidelink channel. In some examples, the second UE 704 may send or include the indication 720 in an SCI message.

[0069] At 708, after the second UE 704 sends the indication 720 to the first UE 702, the first UE 702 may measure the received power (eg, RSRP) of the indication 720 (or a sidelink message / SCI carrying the indication 720).

[0070] At 710, the first UE 702 may determine whether to exclude one or more reserved resources indicated by the second UE 704 based at least in part on the measured received power and whether the one or more reserved resources are associated with a retransmission. In one aspect, as shown in table 722, a first threshold (e.g., a lower threshold) may be defined for resources reserved for initial transmission 724 (e.g., resources 402 and 408), and a second threshold (e.g., a higher threshold) may be defined for resources reserved for (multiple) retransmissions 726 (e.g., resources 404, 406, 410, and 412). Based on the defined thresholds, if the resources are reserved by the second UE 704 for initial transmission and the RSRP of the indication 720 (e.g., the SCI indicating resource reservation) is below the first threshold, the first UE 702 may use the resources reserved by the second UE 704. Similarly, if the resources are reserved by the second UE 704 for retransmission, the first UE 702 may use the resources if the RSRP of the indication 720 is below the second threshold. On the other hand, if the resource is reserved by the second UE 704 for initial transmission and the RSRP of the indication 720 is higher than the first threshold, or if the resource is reserved by the second UE 704 for retransmission and the RSRP of the indication 720 is higher than the second threshold, the first UE 702 may not use the resource reserved by the second UE 704. For example, as shown in Table 722, for the initial transmission 724, the first threshold may be configured as 10 dB, and for the retransmission 726, the second threshold may be configured as 17 dB. If the indication 720 indicates that the second UE 704 reserves the first resource for initial transmission and reserves the second resource and the third resource for retransmission, if the indicated measured RSRP is 15 dB (e.g., 15 dB> the first threshold (10 dB)), the first UE 702 may not use / reclaim the first resource. On the other hand, when the measured RSRP is lower than the second threshold (e.g., 15 dB< the second threshold (17 dB)), the first UE 702 may use the second resource and / or the third resource. By configuring a higher threshold for subsequent retransmission resources, resources reserved for retransmission may have a higher chance of being reclaimed / reused by other UEs, e.g., included as candidate resources for resource selection by the first UE 702. The UE may determine whether resources are reserved for initial transmission or retransmission based on reservation-related information (e.g., indication 720) included in the SCI indicating resource reservation.

[0071] In another aspect, different thresholds may be defined for different retransmission times. Figure 7As shown in Table 728 in , a first threshold value (e.g., 10 dB) may be defined for resources reserved for initial transmission, a second threshold value (e.g., 15 dB) may be defined for resources reserved for first retransmission, and a third threshold value (e.g., 20 dB) may be defined for resources reserved for second retransmission, and so on. Based on the defined threshold values, if the resources are reserved by the second UE 704 for initial transmission and the RSRP of indication 720 is lower than the first threshold value, or if the resources are reserved for the first retransmission and the RSRP of indication 720 is lower than the second threshold value, or if the resources are reserved for the second retransmission and the RSRP of indication 720 is lower than the third threshold value, etc., the first UE 702 may use the resources reserved by the second UE 704. On the other hand, if the resource is reserved for initial transmission and the RSRP of indication 720 is higher than the first threshold, or if the resource is reserved for the first retransmission and the RSRP of indication 720 is higher than the second threshold, or if the resource is reserved for the second retransmission and the RSRP of indication 720 is higher than the third threshold, etc., the first UE 702 may not use the resource reserved by the second UE 704. For example, if indication 720 indicates that the second UE 704 reserves the first resource for initial transmission, the second resource for the first retransmission, and the third resource for the second retransmission, if the measured RSRP of indication 720 is 17 dB (e.g., 17 dB> the first threshold (10 dB) or the second threshold (15 dB)), the first UE 702 may not use / reclaim the first resource or the second resource. On the other hand, when the measured RSRP is lower than the third threshold (e.g., 17 dB< the third threshold (20 dB)), the first UE 702 may use the third resource. By configuring different thresholds for different retransmission resources, resources reserved for a higher number of retransmissions can have a higher chance of being recycled / reused by other UEs. Since a higher number of retransmissions is less likely to be used by the UE that reserved them, the various aspects presented herein can improve resource reuse / recycling of other UEs. In some examples, the first UE 702 can determine the number of retransmissions of the reserved resources based on a redundant version (RV) identifier (ID) associated with the retransmission / reserved resources. For example, the second UE 704 can (e.g., by indicating 720) indicate the number of retransmissions associated with one or more reserved resources (e.g., first retransmission, second retransmission, etc.) by associating one or more reserved resources with an RV ID.

[0072] At 712, if the first UE 702 determines that one or more reserved resources indicated by the second UE 704 have a measured RSRP (e.g., RSRP indicated 720) below their respective thresholds (e.g., first threshold, second threshold, and / or third threshold, etc.), the first UE 702 may reuse / reclaim the one or more reserved resources for its transmission. For example, the first UE 702 may reuse / reclaim the one or more resources to send data to the second UE 704 or another UE 730, etc. In other words, the UE 702 may include the one or more reserved resources as candidate resources in its resource selection, or may determine not to exclude the reserved resources as candidate resources.

[0073] In this way, the UE may be configured to apply different thresholds for different reserved resources based at least in part on whether the reserved resources are associated with retransmissions. For example, the UE may use one threshold to determine whether to exclude resources reserved for initial transmissions from its resource selection, and may use another (e.g., higher) threshold to determine whether to exclude resources reserved for retransmissions from its resource selection. As an illustration, referring back to Figure 4 , the UE may receive a transmission (e.g., an SCI) from the first UE 420 indicating that resource 402 has been reserved by the first UE 420 for an initial transmission and that resources 404 and 406 have been reserved by the first UE 420 for a first retransmission and a second retransmission, respectively. The UE may determine an RSRP threshold for the initial transmission and a different RSRP threshold for the first retransmission. The RSRP threshold for the first retransmission (e.g., for resource 404) may be higher than the RSRP threshold for the initial transmission. Similarly, the UE may also determine an RSRP threshold for the second retransmission (e.g., for resource 406), which may be the same as the RSRP threshold for the first retransmission or may be a different threshold, such as higher than the threshold for the first retransmission. Although this example shows two reserved retransmissions, it may also be applied to resource reservations with more than two retransmissions (e.g., 5, 10, 15 retransmissions, etc.). The UE may be configured to use a different RSRP threshold for each retransmission (eg, first retransmission, second retransmission, xth retransmission, etc.) or for each group of retransmissions (eg, first to second retransmission, third to fourth retransmission, etc.).

[0074] Various aspects presented herein can improve resource reuse / recycling while avoiding resource conflicts because resource reservations for higher retransmissions may have a lower probability of being used by the UE that reserved them than lower retransmission resource reservations. For example, if a UE reserves two future time slots for two retransmissions, the second reserved retransmission may be less likely to occur (e.g., have a lower probability of being used) than the first reserved retransmission because the UE may successfully retransmit data in the first retransmission. By using a higher RSRP threshold for higher retransmission resource reservations, the UE can reduce the number of timeslots from its resource selection window (e.g., Figure 5 502 in ). Therefore, the UE can have a higher probability to recycle / reuse the reserved but unused resources. In other words, by using one threshold for the initial transmission resources and a higher threshold for subsequent retransmissions, the subsequent resources reserved for retransmissions will have a higher chance of being included in the candidate resources for resource selection. This in turn reduces resource exclusion and waste.

[0075] Figure 8 800 is a flowchart of a wireless communication method. The method can be performed by a first UE or a component of the first UE (e.g., UE104, 602, 604, 606, 608, 702; RSU 107, 607; device 310 or 350; apparatus 902; a processing system, which may include a memory 360 and may be a device 350 or a component of the device 350, such as a TX processor 368, an RX processor 356 and / or a controller / processor 359). Optional aspects are shown with dashed lines. The method can reduce resource exclusion and waste of the first UE and / or other sidelink devices. The method can also improve the use of wireless resources in sidelink communications such as V2X or other D2D communications.

[0076] At 802, a first UE may receive an indication of resources reserved for a second UE in a transmission from the second UE, such as in conjunction with Figure 7 For example, at 706, the first UE 702 may receive an indication 720 from the second UE 704 indicating one or more sidelink resource reservations. The transmission may be included in an SCI message sent by the second UE. For example, the message may be based on the sidelink and may be received via a PC5 interface. The message may be sent by the second UE via broadcast, multicast, groupcast, unicast, etc. The receipt of the indication may be, for example, by Fig. 9 The reserved resource determination component 940 and / or the receiving component 930 of the device 902 are executed.

[0077] At 804, the first UE may measure the received power of the transmission from the second UE, such as in conjunction with Figure 7For example, at 708, the first UE 702 may measure the received power of the indication 720 sent from the second UE 704. Thus, the received power may be based on the RSRP of the transmission from the second UE. RSRP may be a linear average of the power contributions of the resource elements carrying the demodulation reference signal. The power of each resource element may be determined based on the energy received during the symbol (e.g., excluding the cyclic prefix). The RSRP measurement may be, for example, determined by Fig. 9 The RSRP measurement component 942 of the device 902 is performed.

[0078] At 806, the first UE may determine a threshold value for the received power based at least in part on whether the reserved resources are associated with a retransmission, such as in conjunction with Figure 7 710 and table 722. For example, if the reserved resources are associated with (multiple) retransmissions, a higher threshold may be assigned than if the reserved resources are used for initial transmissions. The RSRP threshold may be determined, for example, by Fig. 9 The RSRP threshold component 944 of the device 902 in the embodiment is executed.

[0079] At 807, the first UE may allocate different thresholds for the received power based on the number of retransmissions of the reserved resources (eg, for the first retransmission, the second retransmission, the third retransmission, etc.), such as in combination with Figure 7 710 and Table 728. For example, the first UE may set an RSRP threshold for the second retransmission that is higher than its first retransmission. Similarly, the first UE may set another RSRP threshold for the third retransmission that is higher than the second retransmission, and so on. The first UE may be configured to use a different RSRP threshold for each retransmission or for each group of retransmissions (e.g., the first to fourth retransmissions, the fifth to eighth retransmissions, all transmissions after the ninth retransmission, etc.). The number of retransmissions from the second UE may be determined based on a redundant version identifier in the SCI of the sidelink transmission from the second UE. The determination of the RSRP threshold may be, for example, by Fig. 9 The RSRP threshold component 944 of the device 902 in the embodiment is executed.

[0080] At 808, the first UE determines whether to exclude the reserved resources indicated by the second UE based on whether the received power of the transmission from the second UE meets the threshold, such as in conjunction with Figure 7 For example, at 710, the first UE 702 may determine whether to exclude one or more reserved resources indicated by the second UE 704 based on the measured RSRP and based on whether the one or more reserved resources are associated with a retransmission. In this way, the threshold may be determined based at least in part on whether the reserved resources are associated with a retransmission. The determination of whether to exclude the reserved resources indicated by the second UE may be determined, for example, by Fig. 9The resources of the device 902 in include / exclude component 946 for execution.

[0081] For example, at 810, if the received power exceeds a threshold set by or defined for the first UE, the first UE may exclude the reserved resources from resource selection (e.g., exclude them from the candidate resources of the first UE) so that these reserved resources may not be selected by the first UE. On the other hand, if the received power does not exceed the threshold set by or defined for the first UE, at 812, the first UE may determine not to exclude the reserved resources from resource selection (e.g., include the reserved resources in the candidate resources of the first UE). In other words, if the received power of the transmission from the second UE meets the threshold, the first UE may determine to exclude the reserved resources indicated by the second UE, where the threshold may be based at least in part on whether the reserved resources are associated with a retransmission.

[0082] Excluding at 810 or not excluding reserved resources at 812 may be performed as part of maintaining a set of candidate resources for the first UE to select for sidelink transmission. The selection may be performed, for example, by Fig. 9 The sidelink resource selection component 948 of the device 902 in is performed. For example, if the first UE determines to exclude reserved resources, then at 814, the first UE may select one or more resources from the candidate resource set for sidelink transmission. Then, at 816, the first UE may send the sidelink transmission using the one or more resources selected from the candidate resource set. Similarly, if the first UE determines not to exclude reserved resources, then at 818, the first UE may select one or more resources from the candidate resource set that includes reserved resources for sidelink transmission. Then, at 820, the first UE may send the sidelink transmission using the one or more resources selected from the candidate resource set. In this way, the first UE may send the sidelink transmission using the reserved resources. The transmission may be, for example, Fig. 9 The sending component 934 of the device 902 is executed.

[0083] Fig. 9900 is a diagram illustrating an example of a hardware implementation of an apparatus 902. The apparatus 902 is a UE and includes a cellular baseband processor 904 (also referred to as a modem) coupled to a cellular RF transceiver 922 and one or more subscriber identity modules (SIM) cards 920, an application processor 906 coupled to a secure digital (SD) card 908 and a screen 910, a Bluetooth module 912, a wireless local area network (WLAN) module 914, a global positioning system (GPS) module 916, and a power supply 918. The cellular baseband processor 904 communicates with the UE 104 and / or the BS 102 / 180 via the cellular RF transceiver 922. The cellular baseband processor 904 may include a computer-readable storage medium / memory. The computer-readable storage medium / memory may be non-transitory. The cellular baseband processor 904 is responsible for general processing, including executing software stored on a computer-readable storage medium / memory. The software, when executed by the cellular baseband processor 904, enables the cellular baseband processor 904 to perform the various functions described above. The computer-readable storage medium / memory may also be used to store data manipulated by the cellular baseband processor 904 when executing software. The cellular baseband processor 904 also includes a receiving component 930, a communication manager 932, and a transmitting component 934. The communication manager 932 includes one or more of the components shown. The components within the communication manager 932 may be stored in a computer-readable storage medium / memory and / or configured as hardware within the cellular baseband processor 904. The cellular baseband processor 904 may be a component of the device 350 and may include a memory 360 and / or at least one of a TX processor 368, an RX processor 356, and a controller / processor 359. In one configuration, the device 902 may be a modem chip and include only the baseband processor 904, and in another configuration, the device 902 may be an entire wireless device (e.g., see Figure 3 350) and includes additional modules of device 902.

[0084] The communication manager 932 includes a reserved resource determining component 940 configured to receive an indication of resources reserved for the second UE in a transmission from the second UE, for example, as described in conjunction with Figure 8 The communication manager 932 also includes an RSRP measurement component 942, which is configured to measure the received power of the transmission from the second UE, for example, as described in conjunction with Figure 8 The communication manager 932 also includes an RSRP threshold component 944, which is configured to determine a threshold of received power based in part on whether the reserved resources are associated with a retransmission, for example, as described in conjunction with Figure 8The communication manager 932 also includes a resource inclusion / exclusion component 946, which is configured to exclude the reserved resources indicated by the second UE if the received power of the transmission from the second UE meets the threshold, wherein the threshold can be based at least in part on whether the reserved resources are associated with the retransmission, for example, as combined with Figure 8 As described in 808.

[0085] The device may include executing the aforementioned Figure 8 The additional components of each box of the algorithm in the flowchart. Figure 8 Each block in the flowchart of can be performed by a component and the apparatus may include one or more of these components. The component can be one or more hardware components, specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable storage medium for processor implementation, or some combination thereof.

[0086] In one configuration, the apparatus 902, and in particular the cellular baseband processor 904, includes means for receiving, in a transmission from the second UE, an indication of resources reserved for the second UE. The apparatus 902 may also include means for measuring a received power of the transmission from the second UE. The apparatus 902 may also include means for determining to exclude reserved resources indicated by the second UE if the received power of the transmission from the second UE satisfies a threshold, wherein the threshold is based at least in part on whether the reserved resources are associated with a retransmission.

[0087] The aforementioned means may be one or more of the aforementioned components of the apparatus 902, which are configured to perform the functions listed by the aforementioned means. As described above, the apparatus 902 may include a TX processor 368, an RX processor 356, and a controller / processor 359. Thus, in one configuration, the aforementioned means may be a TX processor 368, an RX processor 356, and a controller / processor 359, which are configured to perform the functions listed by the aforementioned means.

[0088] The following examples are merely illustrative, and aspects thereof may be combined with aspects of other embodiments or teachings described herein without limitation.

[0089] Aspect 1 is a method for performing wireless communications at a first UE, comprising: receiving an indication of resources reserved for a second UE in a transmission from the second UE; measuring a received power of the transmission from the second UE; and excluding the reserved resources indicated by the second UE from a set of candidate resources based on the received power of the transmission from the second UE satisfying a threshold, wherein the threshold is based at least in part on whether the reserved resources are associated with a retransmission.

[0090] In aspect 2, the method of aspect 1 further includes: the threshold is based on RSRP.

[0091] In aspect 3, the method of aspect 1 or aspect 2 further includes: the first UE uses a first threshold to determine whether to exclude initial transmission resources, and uses a second threshold to determine whether to exclude retransmission resources.

[0092] In aspect 4, the method of any one of aspects 1-3 further includes: the second threshold is higher than the first threshold.

[0093] In aspect 5, the method of any one of aspects 1-4 further includes: the first UE uses a first threshold to determine whether to exclude a first retransmission resource, and uses a second threshold to determine whether to exclude a subsequent retransmission resource.

[0094] In aspect 6, the method of any one of aspects 1-5 further includes: the second threshold is higher than the first threshold.

[0095] In aspect 7, the method of any one of aspects 1-6 further includes: the threshold is based on the number of retransmissions.

[0096] In aspect 8, the method of any one of aspects 1-7 further includes: the transmission includes a sidelink transmission, and the method further includes: determining the number of retransmissions based on the RV ID in the SCI of the sidelink transmission from the second UE.

[0097] In aspect 9, the method described in any one of aspects 1-8 further includes: selecting one or more resources from the candidate resource set for sidelink transmission after excluding the reserved resources indicated by the second UE; and using the one or more resources to send the sidelink transmission.

[0098] Aspect 10 is an apparatus for wireless communication, comprising at least one processor coupled to a memory and configured to implement the method as described in any one of aspects 1 to 9.

[0099] Aspect 11 is an apparatus for wireless communication, comprising means for implementing the method in any one of aspects 1 to 9.

[0100] Aspect 12 is a non-transitory computer-readable storage medium storing computer-executable code, wherein the code, when executed by a processor, causes the processor to implement the method as described in any one of aspects 1 to 9.

[0101] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is an illustration of an example method. Based on design preferences, it should be understood that the specific order or hierarchy of the blocks in the process / flowchart can be rearranged. In addition, some blocks can be combined or omitted. The attached method claims present the elements of each block in a sample order and are not meant to be limited to the specific order or hierarchy presented.

[0102] The preceding description is provided so that any person skilled in the art can practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not intended to be limited to the various aspects shown herein, but to conform to the full scope consistent with the language claims, wherein unless clearly stated so, the elements mentioned in the singular are not intended to represent "one and only one", but "one or more". The word "exemplary" is used herein to mean "as an example, instance or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred or superior to other aspects. Unless otherwise clearly stated, the term "some" refers to one or more. Combinations such as "at least one of A, B or C", "one or more of A, B or C", "at least one of A, B and C", "one or more of A, B, and C" and "A, B, C or any combination thereof" include any combination of A, B and / or C, and may include multiple A, multiple B or multiple C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements throughout the various aspects described in this disclosure that are known or later become known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be contributed to the public, regardless of whether such disclosure is expressly recited in the claims. Words such as "module," "mechanism," "element," "device," etc. cannot replace the word "mean." Therefore, any claim element shall not be interpreted as a part plus function unless the element is expressly recited using the phrase "means for..."

Claims

1. A method for wireless communication at a first user equipment UE, comprising: receiving, in a transmission from a second UE, an indication of resources reserved for the second UE, wherein the indication includes information regarding whether the resources reserved for the second UE are reserved for an initial transmission or a retransmission; measuring a received power of the transmission from the second UE; comparing a received power of the transmission from the second UE with a first threshold or a second threshold, depending on whether the indication indicates that the reserved resources are reserved for initial transmission or retransmission, wherein the first threshold is used to determine whether to exclude resources for initial transmission and the second threshold is used to determine whether to exclude resources for retransmission; as well as excluding the reserved resources indicated by the second UE from the set of candidate resources based on a comparison of the received power of the transmission from the second UE with a first threshold or a second threshold meeting or exceeding the corresponding threshold, The candidate resource set is resources that can be used for data transmission and / or retransmission of multiple UEs, and the multiple UEs include the first UE and the second UE.

2. The method according to claim 1, further comprising: selecting one or more resources from the set of candidate resources for sidelink transmission after excluding the reserved resources indicated by the second UE; as well as The sidelink transmission is sent using the one or more resources.

3. The method according to claim 1, wherein: The threshold is based on the reference signal received power RSRP.

4. The method according to claim 1, wherein: The first UE uses a second threshold to determine whether to exclude first transmission resources and uses a third threshold to determine whether to exclude subsequent retransmission resources.

5. The method according to claim 4, wherein: The third threshold is higher than the second threshold.

6. The method according to claim 1, wherein: The second threshold is higher than the first threshold.

7. The method according to claim 1, wherein: The second threshold is based on the number of retransmissions.

8. The method according to claim 7, wherein: The transmission comprises a sidelink transmission, and the method further comprises: The number of retransmissions is determined based on a redundancy version RV identifier ID in sidelink control information SCI of the sidelink transmission from the second UE.

9. An apparatus for wireless communication at a first user equipment UE, comprising: means for receiving, in a transmission from a second UE, an indication of resources reserved for the second UE, wherein the indication comprises information regarding whether the resources reserved for the second UE are reserved for an initial transmission or a retransmission; means for measuring received power of the transmission from the second UE; means for comparing a received power of the transmission from the second UE to a first threshold or a second threshold, depending on whether the indication indicates that the reserved resources are reserved for initial transmission or retransmission, wherein the first threshold is used to determine whether to exclude resources for initial transmission and the second threshold is used to determine whether to exclude resources for retransmission; as well as A component for excluding reserved resources indicated by the second UE from a set of candidate resources based on a comparison of the received power of the transmission from the second UE with a first threshold or a second threshold meeting or exceeding the corresponding threshold, wherein the set of candidate resources is resources that can be used for data transmission and / or retransmission of multiple UEs, and the multiple UEs include the first UE and the second UE.

10. The apparatus according to claim 9, further comprising: means for selecting one or more resources from the set of candidate resources for sidelink transmission after excluding the reserved resources indicated by the second UE; as well as Means for sending the sidelink transmission using the one or more resources.

11. The device according to claim 9, wherein: The threshold is based on the reference signal received power RSRP.

12. The device according to claim 9, wherein: The first UE uses a second threshold to determine whether to exclude first transmission resources and uses a third threshold to determine whether to exclude subsequent retransmission resources.

13. The device according to claim 12, wherein: The third threshold is higher than the second threshold.

14. The device according to claim 9, wherein: The second threshold is higher than the first threshold.

15. The device according to claim 9, wherein: The second threshold is based on the number of retransmissions.

16. The device according to claim 15, wherein: The transmission comprises a sidelink transmission, and the apparatus further comprises: A means for determining the number of retransmissions based on a redundancy version RV identifier ID in sidelink control information SCI of the sidelink transmission from the second UE.

17. An apparatus for performing wireless communication at a first user equipment UE, comprising: Memory; as well as at least one processor, coupled to the processor and configured to: receiving, in a transmission from a second UE, an indication of resources reserved for the second UE, wherein the indication includes information regarding whether the resources reserved for the second UE are reserved for an initial transmission or a retransmission; measuring a received power of the transmission from the second UE; comparing a received power of the transmission from the second UE with a first threshold or a second threshold, depending on whether the indication indicates that the reserved resources are reserved for initial transmission or retransmission, wherein the first threshold is used to determine whether to exclude resources for initial transmission and the second threshold is used to determine whether to exclude resources for retransmission; as well as excluding the reserved resources indicated by the second UE from the set of candidate resources based on a comparison of the received power of the transmission from the second UE with a first threshold or a second threshold meeting or exceeding the corresponding threshold, The candidate resource set is resources that can be used for data transmission and / or retransmission of multiple UEs, and the multiple UEs include the first UE and the second UE.

18. The device according to claim 17, wherein: The at least one processor coupled to the memory is further configured to: selecting one or more resources from the set of candidate resources for sidelink transmission after excluding the reserved resources indicated by the second UE; and The sidelink transmission is sent using the one or more resources.

19. The device according to claim 17, wherein: The threshold is based on the reference signal received power RSRP.

20. The device according to claim 17, wherein: The first UE uses a second threshold to determine whether to exclude first transmission resources and uses a third threshold to determine whether to exclude subsequent retransmission resources.

21. The device according to claim 20, wherein: The third threshold is higher than the second threshold.

22. The device according to claim 17, wherein: The second threshold is higher than the first threshold.

23. The device according to claim 17, wherein: The second threshold is based on the number of retransmissions.

24. The device according to claim 23, wherein: The transmission comprises a sidelink transmission, the at least one processor coupled to the memory being further configured to: The number of retransmissions is determined based on a redundancy version RV identifier ID in sidelink control information SCI of the sidelink transmission from the second UE.

25. A non-transitory computer-readable medium storing computer-executable instructions that, when executed by a processor, cause the processor to: receiving, in a transmission from a second UE, an indication of resources reserved for the second UE, wherein the indication includes information regarding whether the resources reserved for the second UE are reserved for an initial transmission or a retransmission; measuring a received power of the transmission from the second UE; comparing a received power of the transmission from the second UE with a first threshold or a second threshold, depending on whether the indication indicates that the reserved resources are reserved for initial transmission or retransmission, wherein the first threshold is used to determine whether to exclude resources for initial transmission and the second threshold is used to determine whether to exclude resources for retransmission; as well as excluding the reserved resources indicated by the second UE from the set of candidate resources based on a comparison of the received power of the transmission from the second UE with a first threshold or a second threshold meeting or exceeding the corresponding threshold, The candidate resource set is resources that can be used for data transmission and / or retransmission of multiple UEs, and the multiple UEs include the first UE and the second UE.

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