Link Management of Sidelink

Abstract

Aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine whether a sidelink to another UE is inactive; and disable the sidelink at least in part based on determining that the sidelink is inactive. Numerous other aspects are provided.

Description

[0001] Cross - Reference to Related Applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 007,056, entitled "LINK MANAGEMENT FOR SIDELINK", filed on April 8, 2020, and U.S. Non - Provisional Patent Application No. 17 / 167,935, entitled "LINK MANAGEMENT FOR SIDELINK", filed on February 4, 2021, which are hereby incorporated by reference in their entirety.

[0003] Field of Disclosure

[0004] Aspects of the present disclosure generally relate to wireless communication and relate to techniques and apparatus for link management for sidelink.

[0005] Background

[0006] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ a multiple access technology capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). 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, Time Division - Synchronous Code Division Multiple Access (TD - SCDMA) systems, and Long Term Evolution (LTE). LTE / Advanced LTE is an enhanced set of the Universal Mobile Telecommunications System (UMTS) mobile standards promulgated by the Third Generation Partnership Project (3GPP).

[0007] A wireless network may include several base stations (BSs) capable of supporting communication of several user equipments (UEs). The UEs may communicate with the BSs via a downlink and an uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, the BS may be referred to as a B - node, gNB, access point (AP), radio head, transmission and reception point (TRP), New Radio (NR) BS, or 5G B - node.

[0008] The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipments to communicate at the urban, national, regional, and even global levels. NR (which may also be referred to as 5G) is an enhanced set of the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by using orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and / or SC-FDM (e.g., also referred to as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), and supporting beamforming, multiple input multiple output (MIMO) antenna technology, and carrier aggregation to improve spectral efficiency, reduce costs, improve services, utilize new spectrums, and better integrate with other open standards. However, as the demand for mobile broadband access continues to grow, there is a need for further improvements to LTE, NR, and other radio access technologies.

[0009] Overview

[0010] In some aspects, a wireless communication method performed by a user equipment (UE) may include: determining whether a sidelink to another UE is inactive; and disabling the sidelink at least in part based on determining that the sidelink is inactive.

[0011] In some aspects, a wireless communication method performed by a UE may include: determining whether the quality of a sidelink to another UE meets a quality threshold; and disabling the sidelink at least in part based on determining that the quality of the sidelink does not meet the quality threshold.

[0012] In some aspects, a wireless communication method performed by a UE may include: determining whether the unavailability of a sidelink to another UE meets an unavailability threshold; and disabling the sidelink at least in part based on determining that the unavailability of the sidelink meets the unavailability threshold.

[0013] In some aspects, a wireless communication method performed by a base station may include: receiving, from a first UE, a message indicating that the first UE is releasing a sidelink to a second UE; and adjusting one or more relay procedures associated with the first UE and the second UE at least in part based on receiving the message.

[0014] In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine whether a sidelink to another UE is inactive; and disable the sidelink at least in part based on determining that the sidelink is inactive.

[0015] In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine whether the quality of a sidelink to another UE meets a quality threshold; and disable the sidelink at least in part based on determining that the quality of the sidelink does not meet the quality threshold.

[0016] In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: determine whether the unavailability of a sidelink to another UE meets an unavailability threshold; and disable the sidelink at least in part based on determining that the unavailability of the sidelink meets the unavailability threshold.

[0017] In some aspects, a base station for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to: receive, from a first UE, a message indicating that the first UE is releasing a sidelink to a second UE; and adjust one or more relay procedures associated with the first UE and the second UE at least in part based on receiving the message.

[0018] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to perform operations including: determining whether a sidelink to another UE is inactive; and disabling the sidelink at least in part based on determining that the sidelink is inactive.

[0019] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to perform operations including: determining whether the quality of a sidelink to another UE meets a quality threshold; and disabling the sidelink at least in part based on determining that the quality of the sidelink does not meet the quality threshold.

[0020] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to perform operations including: determining whether the unavailability of a sidelink to another UE meets an unavailability threshold; and disabling the sidelink at least in part based on determining that the unavailability of the sidelink meets the unavailability threshold.

[0021] In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a base station, may cause the one or more processors to perform operations including: receiving, from a first UE, a message indicating that the first UE is releasing a sidelink with a second UE; and adjusting, at least in part based on receiving the message, one or more relay procedures associated with the first UE and the second UE.

[0022] In some aspects, a device for wireless communication may include: means for determining whether a sidelink to another device is inactive, and means for disabling the sidelink, at least in part based on determining that the sidelink is inactive.

[0023] In some aspects, a device for wireless communication may include: means for determining whether the quality of a sidelink to another device meets a quality threshold; and means for disabling the sidelink, at least in part based on determining that the quality of the sidelink does not meet the quality threshold.

[0024] In some aspects, a device for wireless communication may include: means for determining whether the unavailability of a sidelink to another device meets an unavailability threshold; and means for disabling the sidelink, at least in part based on determining that the unavailability of the sidelink meets the unavailability threshold.

[0025] In some aspects, a device for wireless communication may include: means for receiving, from a first UE, a message indicating that the first UE is releasing a sidelink with a second UE; and means for adjusting, at least in part based on receiving the message, one or more relay procedures associated with the first UE and the second UE.

[0026] Aspects generally include methods, apparatuses, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and / or processing systems as substantially described herein with reference to the figures and the description, as illustrated in the figures and the description.

[0027] The foregoing has outlined rather broadly the features and technical advantages of examples in accordance with the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The disclosed concepts and specific examples may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, both as to their organization and operation methods, as well as the associated advantages, will be better understood when considered in conjunction with the following description in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description, and not as a definition of the limitations of the claims. Brief Description of the Drawings

[0029] To understand the above-described features of the present disclosure in detail, the content briefly summarized above can be described more specifically with reference to various aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only some exemplary aspects of the present disclosure and should not be considered to limit its scope, as the description may admit other equally effective aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0030] Figure 1 is a diagram illustrating an example of a wireless network according to the present disclosure.

[0031] Figure 2 is a diagram illustrating an example in which a base station and a user equipment (UE) are in communication in a wireless network according to the present disclosure.

[0032] Figure 3 is a diagram illustrating an example of sidelink communication according to the present disclosure.

[0033] Figure 4 is a diagram illustrating an example of sidelink communication and access link communication according to the present disclosure.

[0034] Figure 5 is a diagram illustrating an example of link management of a sidelink according to the present disclosure.

[0035] Figure 6 is a diagram illustrating an example process, such as that performed by a UE, according to the present disclosure.

[0036] Figure 7 is a diagram illustrating an example process, such as that performed by a UE, according to the present disclosure.

[0037] Figure 8 is a diagram illustrating an example process, such as that performed by a UE, according to the present disclosure.

[0038] Figure 9 is a diagram illustrating an example process, such as that performed by a base station, according to the present disclosure.

[0039] Detailed Description

[0040] Aspects of the present disclosure are described more fully hereinafter with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art should appreciate that the scope of the present disclosure is intended to cover any aspect of the present disclosure disclosed herein, whether implemented independently or combined with any other aspect of the present disclosure. For example, any number of the aspects set forth herein may be used to implement an apparatus or practice a method. Additionally, the scope of the present disclosure is intended to cover such apparatus or methods practiced using other structures, functionality, or a combination of structures and functionality that supplement or are additional to the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the present disclosure disclosed herein may be implemented by one or more elements of a claim.

[0041] Certain aspects of a telecommunications system will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in detail hereinafter and illustrated in the drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0042] It should be noted that although aspects herein may be described using terms typically associated with 5G or NR radio access technology (RAT), aspects of the present disclosure may be applied to other RATs such as 3G RAT, 4G RAT, and / or RATs after 5G (e.g., 6G).

[0043] Figure 1 is a diagram illustrating an example of a wireless network 100 in accordance with the present disclosure. The wireless network 100 may be a 5G (NR) network and / or an LTE network, etc., or may include elements thereof. The wireless network 100 may include several base stations 110 (shown as BS110a, BS 110b, BS 110c, and BS 110d) and other network entities. A base station (BS) is an entity that communicates with user equipment (UE) and may also be referred to as an NR BS, Node B, gNB, 5G Node B (NB), access point, or transmission reception point (TRP). Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to the coverage area of a BS and / or the BS subsystem serving that coverage area, depending on the context in which the term is used.

[0044] The BS can provide communication coverage for macro cells, picocells, femtocells, and / or another type of cell. A macro cell can cover a relatively large geographical area (e.g., with a radius of several kilometers) and can allow unconstrained access by UEs with service subscriptions. A picocell can cover a relatively small geographical area and can allow unconstrained access by UEs with service subscriptions. A femtocell can cover a relatively small geographical area (e.g., a residence) and can allow constrained access by UEs associated with the femtocell (e.g., UEs in a closed subscriber group (CSG)). The BS for a macro cell can be referred to as a macro BS. The BS for a picocell can be referred to as a pico BS. The BS for a femtocell can be referred to as a femto BS or a home BS. In Figure 1 the example shown in, BS 110a can be a macro BS for macro cell 102a, BS 110b can be a pico BS for picocell 102b, and BS 110c can be a femto BS for femtocell 102c. The BS can support one or more (e.g., three) cells. The terms "eNB", "base station", "NR BS", "gNB", "TRP", "AP", "B node", "5G NB", and "cell" are used interchangeably herein.

[0045] In some aspects, the cell may not have to be stationary, and the geographical area of the cell can move according to the position of the mobile BS. In some aspects, the BSs can be interconnected with each other and / or interconnected to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as direct physical connections or virtual networks, using any suitable transport network.

[0046] The wireless network 100 can also include relay stations. A relay station is an entity that can receive the transmission of data from an upstream station (e.g., a BS or a UE) and send the transmission of the data to a downstream station (e.g., a UE or a BS). A relay station can also be a UE that can relay transmissions for other UEs. In Figure 1 the example shown in, relay BS 110d can communicate with macro BS 110a and UE 120d to facilitate communication between BS 110a and UE 120d. The relay BS can also be referred to as a relay station, a relay base station, or a relay.

[0047] The wireless network 100 can be a heterogeneous network that includes different types of BSs (such as macro BSs, pico BSs, femto BSs, and / or relay BSs). These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 5 to 40 watts), while pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 watts).

[0048] The network controller 130 can be coupled to a set of BSs and can provide coordination and control of these BSs. The network controller 130 can communicate with each BS via a backhaul. These BSs can also communicate with each other directly or indirectly via a wireless or wired backhaul.

[0049] UEs 120 (e.g., 120a, 120b, 120c) can be dispersed throughout the wireless network 100, and each UE can be stationary or mobile. UEs can also be referred to as access terminals, terminals, mobile stations, subscriber units, stations, etc. A UE can be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, a ultrabook, a medical device or equipment, a biometric sensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle component or sensor, a smart meter / sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium.

[0050] Some UEs may be considered machine type communication (MTC) UEs, or evolved or enhanced machine type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, and / or location tags, which may communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node may provide connectivity to a network (e.g., a wide area network such as the Internet or a cellular network) or provide connectivity to the network via, for example, a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices, and / or may be implemented as narrowband IoT (NB-IoT) devices. Some UEs may be considered customer premise equipment (CPE). UE 120 may be included inside a housing that houses components of UE 120, such as a processor component and / or a memory component. In some aspects, the processor component and the memory component may be coupled together. For example, the processor component (e.g., one or more processors) and the memory component (e.g., a memory) may be operatively coupled, communicatively coupled, electronically coupled, and / or electrically coupled.

[0051] Generally, any number of wireless networks may be deployed in a given geographical area. Each wireless network may support a specific RAT and may operate on one or more frequencies. The RAT may also be referred to as a radio technology and / or an air interface. The frequency may also be referred to as a carrier and / or a frequency channel. Each frequency may support a single RAT in a given geographical area to avoid interference between wireless networks of different RATs. In some cases, an NR or 5G RAT network may be deployed.

[0052] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., communicate with each other without using the base station 110 as an intermediary). For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols or vehicle-to-infrastructure (V2I) protocols), and / or mesh networks. In this case, UE 120 may perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by the base station 110.

[0053] As indicated above, Figure 1 is provided as an example. Other examples may be different from the example depicted with respect to Figure 1 that is depicted.

[0054] Devices of the wireless network 100 can communicate using the electromagnetic spectrum, which can be subdivided into various categories, frequency bands, channels, etc. based on frequency or wavelength. For example, devices of the wireless network 100 can communicate using an operating frequency band having a first frequency range (FR1) and / or can communicate using an operating frequency band having a second frequency range (FR2). The first frequency range (FR1) can span from 410 MHz to 7.125 GHz, and the second frequency range (FR2) can span from 24.25 GHz to 52.6 GHz. The frequencies between FR1 and FR2 are sometimes referred to as mid-band frequencies. Although a part of FR1 is greater than 6 GHz, FR1 is generally referred to as the "sub-6 GHz" band. Similarly, although different from the extremely high frequency (EHF) band (30 GHz - 300 GHz) identified by the International Telecommunication Union (ITU) as the "millimeter wave" band, FR2 is generally referred to as the "millimeter wave" band. Thus, unless specifically stated otherwise, it should be understood that if used herein, terms such as "sub-6 GHz" can broadly represent frequencies less than 6 GHz, frequencies within FR1, and / or mid-band frequencies (e.g., greater than 7.125 GHz). Similarly, unless specifically stated otherwise, it should be understood that if used herein, terms such as "millimeter wave" can broadly represent frequencies within the EHF band, frequencies within FR2, and / or mid-band frequencies (e.g., less than 24.25 GHz). It is contemplated that the frequencies included in FR1 and FR2 can be modified, and the techniques described herein apply to those modified frequency ranges.

[0055] Figure 2 FIG. 200 is a diagram illustrating an example 200 in which a base station 110 and a UE 120 are in communication in the wireless network 100 according to the present disclosure. The base station 110 can be equipped with T antennas 234a to 234t, and the UE 120 can be equipped with R antennas 252a to 252r, where generally T≥1 and R≥1.

[0056] At base station 110, transmit processor 220 may receive data for one or more UEs from data source 212, select one or more modulation and coding schemes (MCSs) for a UE at least in part based on channel quality indicators (CQIs) received from each UE, process (e.g., encode and modulate) the data for the UE at least in part based on the MCS selected for each UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI)) and control information (e.g., CQI requests, grants, higher layer signaling), and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signal (CRS), demodulation reference signal (DMRS)) and synchronization signals (e.g., primary synchronization signal (PSS) or secondary synchronization signal (SSS)). Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, control symbols, overhead symbols, and / or reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process its respective output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.

[0057] At the UE 120, antennas 252a through 252r may receive downlink signals from the base station 110 and / or other base stations and may provide the received signals to demodulators (DEMOD) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, down-convert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM) to obtain received symbols. The MIMO detector 256 may obtain the received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols when applicable, and provide detected symbols. The receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide the decoded data for the UE 120 to the data sink 260, and provide the decoded control information and system information to the controller / processor 280. The term “controller / processor” may refer to one or more controllers, one or more processors, or a combination thereof. The channel processor may determine the reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and / or CQI, or other examples. In some aspects, one or more components of the UE 120 may be included in a housing.

[0058] The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292. The network controller 130 may include, for example, one or more devices in a core network. The network controller 130 may communicate with the base station 110 via the communication unit 294.

[0059] Antennas (e.g., antennas 234a through 234t and / or antennas 252a through 252r) may include one or more antenna panels, antenna groups, antenna element sets, and / or antenna arrays, etc., or may be included therein. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include one or more antenna elements. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include coplanar antenna element sets and / or non-coplanar antenna element sets. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include antenna elements within a single housing and / or antenna elements within multiple housings. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include one or more antenna elements coupled to one or more transmission and / or reception components (such as Figure 2 one or more components) of

[0060] On the uplink, at the UE 120, the transmit processor 264 may receive and process data from the data source 262 and control information from the controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, and / or CQI). The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by the TX MIMO processor 266 when applicable, further processed by the modulators 254a to 254r (e.g., for DFT-s-OFDM or CP-OFDM), and transmitted to the base station 110. In some aspects, the modulator and demodulator (e.g., MOD / DEMOD 254) of the UE 120 may be included in the modem of the UE 120. In some aspects, the UE 120 includes a transceiver. The transceiver may include any combination of antennas 252, modulator and / or demodulator 254, MIMO detector 256, receive processor 258, transmit processor 264, and / or TX MIMO processor 266. The transceiver may be used by a processor (e.g., controller / processor 280) and the memory 282 to perform aspects of any of the methods described herein, e.g., as described with reference to Figures 1 - 9 as described.

[0061] At the base station 110, the uplink signals from the UE 120 and other UEs may be received by the antennas 234, processed by the demodulator 232, detected by the MIMO detector 236 when applicable, and further processed by the receive processor 238 to obtain the decoded data and control information transmitted by the UE 120. The receive processor 238 may provide the decoded data to the data sink 239 and the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The base station 110 may include a scheduler 246 to schedule the UE 120 for downlink and / or uplink communication. In some aspects, the modulator and demodulator (e.g., MOD / DEMOD 232) of the base station 110 may be included in the modem of the base station 110. In some aspects, the base station 110 includes a transceiver. The transceiver may include any combination of antennas 234, modulator and / or demodulator 232, MIMO detector 236, receive processor 238, transmit processor 220, and / or TX MIMO processor 230. The transceiver may be used by a processor (e.g., controller / processor 240) and the memory 242 to perform aspects of any of the methods described herein, e.g., as described with reference to Figures 1 - 9 as described.

[0062] The controller / processor 240 of base station 110, the controller / processor 280 of UE 120, and / or Figure 2 any other component(s) of may perform one or more techniques associated with link management of the sidelink, as described in more detail elsewhere herein. For example, the controller / processor 240 of base station 110, the controller / processor 280 of UE 120, and / or Figure 2 any other component(s) of may execute or direct, for example Figure 6 process 600 of Figure 7 process 700 of Figure 8 process 800 of Figure 9 process 900 of, and / or operations of other processes as described herein. Memories 242 and 282 may store data and program code for base station 110 and UE 120, respectively. In some aspects, memory 242 and / or memory 282 may include: a non-transitory computer-readable medium storing one or more instructions for wireless communication (e.g., code and / or program code). For example, when the one or more instructions are executed (e.g., directly executed, or after compilation, transformation, and / or interpretation) by one or more processors of base station 110 and / or UE 120, the one or more processors, UE 120, and / or base station 110 may be caused to execute or direct, for example Figure 6 process 600 of Figure 7 process 700 of Figure 8 process 800 of Figure 9 process 900 of, and / or operations of other processes described herein. In some aspects, executing the instructions may include running the instructions, transforming the instructions, compiling the instructions, and / or interpreting the instructions, etc.

[0063] Although Figure 2 the boxes in are illustrated as different components, the functions described above with respect to these boxes may be implemented using a single hardware, software, or combined component, or a combination of various components. For example, the functions described with respect to transmit processor 264, receive processor 258, and / or TX MIMO processor 266 may be executed by or under the control of controller / processor 280.

[0064] In some aspects, UE 120 may include: means for determining whether a sidelink to another UE is inactive; means for disabling the sidelink based at least in part on determining that the sidelink is inactive, etc. In some aspects, such means may include in combination with Figure 2One or more components of the described UE 120, such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, and / or receive processor 258.

[0065] In some aspects, UE 120 may include: means for determining whether the quality of a sidelink to another UE meets a quality threshold; means for disabling the sidelink at least in part based on determining that the quality of the sidelink does not meet the quality threshold, and so on. In some aspects, such means may include in combination Figure 2 One or more components of the described UE 120, such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, and so on.

[0066] In some aspects, UE 120 may include: means for determining whether the unavailability of a sidelink to another UE meets an unavailability threshold; means for disabling the sidelink at least in part based on determining that the sidelink meets the unavailability threshold, and so on. In some aspects, such means may include in combination Figure 2 One or more components of the described UE 120, such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, and so on.

[0067] In some aspects, base station 110 may include: means for receiving from a first UE a message indicating that the first UE is releasing a sidelink to a second UE; means for adjusting one or more relay procedures associated with the first UE and the second UE at least in part based on receiving the message, and so on. In some aspects, such means may include in combination Figure 2 One or more components of the described base station 110, such as antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, transmit processor 220, TX MIMO processor 230, MOD 232, and / or antenna 234.

[0068] As indicated above, Figure 2 is provided as an example. Other examples may differ from the example depicted with respect to Figure 2 the example depicted.

[0069] Figure 3 is a diagram illustrating example 300 of sidelink communication in accordance with the present disclosure.

[0070] As Figure 3 shown, the first wireless communication device 305-1 may communicate with a second wireless communication device 305-2 (and one or more other wireless communication devices 305) via one or more sidelink channels 310. The wireless communication devices 305-1 and 305-2 may use one or more sidelink channels 310 to communicate for peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) communication (e.g., which may include vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, vehicle-to-pedestrian (V2P) communication), and / or mesh networking. In some aspects, the wireless communication devices 305 (e.g., the wireless communication device 305-1 and / or the wireless communication device 305-2) may correspond to one or more user equipment (UE) 120, base stations (BS) 110, integrated access and backhaul nodes, etc. In some aspects, one or more sidelink channels 310 may use the PC5 interface and / or may operate in a high-frequency band (e.g., the 5.9 GHz band). Additionally or alternatively, the wireless communication devices 305 may use global navigation satellite system (GNSS) timing to synchronize the timing of transmission time intervals (TTIs) (e.g., frames, subframes, time slots, symbols).

[0071] As further shown in Figure 3 it, the one or more sidelink channels 310 may include a physical sidelink control channel (PSCCH) 315, a physical sidelink shared channel (PSSCH) 320, and / or a physical sidelink feedback channel (PSFCH) 325. The PSCCH 315 may be used to convey control information, which is similar to the physical downlink control channel (PDCCH) and / or the physical uplink control channel (PUCCH) for cellular communication with the BS 110 via an access link or an access channel. The PSSCH 320 may be used to convey data, which is similar to the physical downlink shared channel (PDSCH) and / or the physical uplink shared channel (PUSCH) for cellular communication with the BS 110 via an access link or an access channel. For example, the PSCCH 315 may carry sidelink control information (SCI) 330, which may indicate various control information for sidelink communication, such as one or more resources (e.g., time resources, frequency resources, spatial resources, etc.), where a transport block (TB) 335 may be carried on the PSSCH 320. The TB 335 may include data. The PSFCH 325 may be used to convey sidelink feedback 340, such as hybrid automatic repeat request (HARQ) feedback (e.g., acknowledgement or negative acknowledgement (ACK / NACK) information), transmit power control (TPC), and / or scheduling request (SR).

[0072] In some aspects, HARQ feedback (ACK / NACK) for the downlink Uu may be carried on an uplink channel (such as in the physical uplink control channel) or piggybacked on the physical uplink shared channel. The HARQ feedback may acknowledge downlink data on the PDSCH or a downlink grant (SPS release) on the PDSCH. The HARQ feedback may use a semi-static codebook (if no grant is received, ACK / NACK bits are sent) or a dynamic codebook (if a grant is received, ACK / NACK bits will be sent). However, there are some additional considerations for sidelinks. For example, the stages of a multi-stage grant may be transmitted by different nodes (the grant may be split between Uu downlink control information and the SCI). In addition, a single UE may communicate with multiple UEs on multiple sidelinks (unicast or multicast). The UE may relay the grant from other UEs.

[0073] In some aspects, one or more sidelink channels 310 may use a resource pool. For example, specific resource blocks (RBs) may be used across time to transmit scheduling assignments (e.g., included in the SCI 330) in subchannels. In some aspects, data transmission associated with the scheduling assignment (e.g., on the PSSCH 320) may occupy adjacent RBs in the same subframe as the scheduling assignment (e.g., using frequency division multiplexing). In some aspects, the scheduling assignment and the associated data transmission are not transmitted on adjacent RBs.

[0074] In some aspects, the wireless communication device 305 may operate using a transmission mode in which resource selection and / or scheduling is performed by the wireless communication device 305 (e.g., rather than the BS 110). In some aspects, the wireless communication device 305 may perform resource selection and / or scheduling by sensing the channel availability for transmission. For example, the wireless communication device 305 may measure RSSI parameters associated with various sidelink channels (e.g., sidelink-RSSI (S-RSSI) parameters); may measure RSRP parameters associated with various sidelink channels (e.g., PSSCH-RSRP parameters); may measure RSRQ parameters associated with various sidelink channels (e.g., PSSCH-RSRQ parameters), etc.; and may select a channel for transmitting sidelink communication based at least in part on the (such) measurement results.

[0075] Additionally or alternatively, the wireless communication device 305 may use the SCI 330 received in the PSCCH 315 (which may indicate the occupied resources and / or channel parameters) to perform resource selection and / or scheduling. Additionally or alternatively, the wireless communication device 305 may perform resource selection and / or scheduling by determining the channel busy rate (CBR) associated with various sidelink channels, which may be used for rate control (e.g., by indicating the maximum number of resource blocks that the wireless communication device 305 may use for a particular set of subframes).

[0076] In a transmission mode in which resource selection and / or scheduling is performed by the wireless communication device 305, the wireless communication device 305 may generate sidelink grants and may transmit these grants in the SCI 330. The sidelink grants may indicate, for example, one or more parameters (e.g., transmission parameters) to be used for an upcoming sidelink transmission, such as one or more resource blocks (e.g., for the TB 335) to be used for an upcoming sidelink transmission on the PSSCH 320, one or more subframes to be used for an upcoming sidelink transmission, the modulation and coding scheme (MCS) to be used for an upcoming sidelink transmission, etc. In some aspects, the wireless communication device 305 may generate a sidelink grant that indicates one or more parameters for semi-persistent scheduling (SPS), such as the periodicity of the sidelink transmission. Additionally or alternatively, the wireless communication device 305 may generate sidelink grants for event-driven scheduling (such as for on-demand sidelink messages).

[0077] As indicated above, Figure 3 is provided as an example. Other examples may be different from the example described with respect to Figure 3 the example

[0078] Figure 4 is a diagram illustrating an example 400 of sidelink communication and access link communication in accordance with the present disclosure.

[0079] As Figure 4 shown, the wireless communication device 405 and the wireless communication device 410 may communicate with each other via a sidelink, as described above in connection with Figure 3As described. As further shown, in some sidelink modes, BS 110 may communicate with wireless communication device 405 via a first access link. Wireless communication device 405 and / or wireless communication device 410 may correspond to one or more UEs 120, BS 110, and / or integrated access and backhaul (IAB) nodes. As an example, a "sidelink" may refer to a direct link between UEs 120, and an "access link" may refer to a direct link between BS 110 and UE 120. Sidelink communication may be transmitted over the PC5 interface via the sidelink, and access link communication may be transmitted via the access link. Access link communication may be downlink communication (from BS 110 to UE 120) or uplink communication (from UE 120 to BS 110) on the Uu interface.

[0080] In the case where BS 110 allocates resources for sidelink transmission, communication between wireless communication device 405 and wireless communication device 410 may be referred to as mode 1 sidelink communication. In mode 1, wireless communication device 405 may be a relay UE for wireless communication device 410 (remote UE). In the case where BS 110 is not involved, communication between wireless communication device 405 and wireless communication device 410 may be referred to as mode 2 sidelink communication.

[0081] As indicated above, Figure 4 is provided as an example. Other examples may be different from the example regarding Figure 4 described.

[0082] As described above, a wireless communication device may communicate with a sidelink. However, if a wireless communication device attempts to maintain an inactive, degraded, or frequently unavailable sidelink (e.g., PSSCH), the wireless communication device may waste power and signaling resources. For example, the sidelink may become inactive for a long period of time, the quality may severely degrade, or a frequently busy frequency channel may be used (continuous channel sensing failure). Some aspects described herein enable a wireless communication device to determine whether to maintain or release a sidelink. If the sidelink is disabled or released appropriately, the wireless communication device may save power and signaling resources for maintaining the sidelink and monitoring the corresponding PSCCH. In some aspects, the wireless communication device may report to other wireless communication devices and / or base stations that the sidelink has been released.

[0083] Figure 5 is a diagram illustrating example 500 of link management of a sidelink according to the present disclosure. Figure 5 It shows base stations (BS) 510 (e.g., Figure 1 , 2 and BS 110 depicted in 4) and wireless communication devices 520 (e.g., Figure 1 and2 the UE 120 depicted in Figure 3 the wireless communication device 305-1 depicted in Figure 4 the wireless communication device 405). The wireless communication device 520 may be a relay UE. In some scenarios, the wireless communication device 520 does not communicate with the BS 510. Figure 5 Also shown is a wireless communication device 530 that can communicate with the wireless communication device 520 but not with the BS 510 (e.g., the UE 120, Figure 3 the wireless communication device 305-2 depicted in Figure 4 the wireless communication device 410). The wireless communication device 530 may be a remote UE. In some aspects, the wireless communication device 520 and / or the wireless communication device 530 may be located in a vehicle, on a pedestrian, and / or on infrastructure.

[0084] As shown by reference numeral 540, the wireless communication device 520 may determine whether the sidelink between the wireless communication device 520 and the wireless communication device 530 is inactive, degraded, and / or frequently unavailable. As shown by reference numeral 545, the wireless communication device 520 may disable the sidelink at least in part based on the determination that the sidelink is inactive, degraded, and / or busy. The wireless communication device 520 may thus interrupt communication on the sidelink on the PSSCH and / or may interrupt monitoring the PSCCH. As a result, the wireless communication device 520 and the wireless communication device 530 may save power and signaling resources.

[0085] In some aspects, the wireless communication device 520 may determine that the sidelink is inactive. For example, the wireless communication device 520 may determine whether the sidelink is inactive by determining whether an inactivity timer on the sidelink meets an inactivity duration threshold (e.g., inactivity duration, traffic volume). Inactivity may include no data transmission on the sidelink. Inactivity may also include no control transmission on the sidelink. The wireless communication device 520 may disable the sidelink at least in part based on determining that the timer meets the inactivity duration threshold. For example, an inactivity duration of 30 seconds may exceed an inactivity duration threshold of 25 seconds. The duration of the timer may be preconfigured at the wireless communication device 520 and / or may be shared or negotiated between the wireless communication device 520 and the wireless communication device 530 during the establishment of the sidelink. The timer may be started or restarted by the transmission or reception of new data. The new data may be the first transmission in a HARQ process. In some aspects, such as in mode 1, the timer may be reset by the transmission or reception indicated by a PDSCH from the BS 510.

[0086] In some aspects, the wireless communication device 520 may determine that the sidelink is inactive by predicting that there will be no communication on the sidelink for a period of time. The wireless communication device 520 may make the prediction based at least in part on the following: the most recent communication from the wireless communication device 530, the traffic pattern on the sidelink at a certain time of day, the location and / or orientation of the wireless communication device 520, the location and / or orientation of the wireless communication device 530, and / or nearby activity.

[0087] In some aspects, the wireless communication device 520 may determine a quality degradation of the sidelink. For example, the wireless communication device 530 may transmit a reference signal for the wireless communication device 520 to measure. The reference signal may be the same reference signal used on the Uu link, such as a synchronization signal block, a channel state information reference signal (e.g., periodic, semi-persistent, aperiodic), or DMRS. The wireless communication device 520 and the wireless communication device 530 may negotiate which reference signals to use. In some aspects, the wireless communication device 520 may periodically measure the radio link quality of the sidelink using the reference signal. The wireless communication device 520 may determine the L1-RSRP parameter, the RSSI parameter, and / or the RSRQ parameter.

[0088] In some aspects, the wireless communication device 520 may determine that the quality of the sidelink does not meet a quality threshold. For example, if the measured parameter is below the threshold, the wireless communication device 520 may detect a sidelink link failure (SLF). The wireless communication device 520 may count the SLFs. In some aspects, the wireless communication device 520 may determine the SLF count for each specified number of measurement occasions. If the count of SLFs meets the failure threshold for the specified number of measurement occasions, the wireless communication device 520 may determine that the quality of the sidelink does not meet the quality threshold and may disable the sidelink. For example, the failure threshold may be five SLFs within the most recent ten measurement occasions. If the threshold is met, the wireless communication device 520 may release the sidelink.

[0089] Alternatively or additionally, the wireless communication device 520 may count the SLFs during an SLF detection timer. Each SLF may start or restart the SLF detection timer and increment the count of SLFs by 1. When the SLF detection timer expires, the count of SLFs may be reset to zero. The wireless communication device 520 may determine that the quality of the link does not meet the quality threshold based at least in part on the determination that the count of SLFs during the SLF detection timer meets a failure count threshold. In some aspects, the duration of the SLF detection timer may be at least in part based on an integer multiple of the time period of the link quality measurement.

[0090] In some aspects, the wireless communication device 520 may determine that the sidelink is often unavailable or too busy. For example, the wireless communication device 520 may determine whether the unavailability amount of the sidelink meets an unavailability threshold and disable the sidelink at least partially based on the determination that the unavailability amount of the sidelink meets the unavailability threshold. For example, in mode 2, before the wireless communication device 520 can transmit to the wireless communication device 530 on the sidelink, the wireless communication device 520 may check the availability of the sidelink by sensing the energy level on the channel for a certain amount of time. This may be a listen-before-talk (LBT) procedure. If a busy signal is detected for a certain period of time, the channel is considered busy and the LBT procedure fails. If the sidelink is unavailable for a threshold amount of time, the wireless communication device may determine that the sidelink is too busy and disable the sidelink. The threshold amount of time may be at least partially based on the LBT procedure failure count meeting a failure count threshold, the percentage or fraction of the time the sidelink is busy, and / or the total amount of busy time.

[0091] In some aspects, as indicated by reference numeral 550, the wireless communication device 520 may transmit an indication that the sidelink is released (e.g., via PC5 radio resource control (RRC) signaling). In some aspects, the wireless communication device 520 may provide an indication of why the sidelink is released (e.g., inactive, degraded, too busy). The wireless communication device 520 may transmit the indication to the wireless communication device 530 as a result of releasing the sidelink, such that the wireless communication device 530 interrupts monitoring the PSCCH and / or takes other steps. In some aspects, the wireless communication device 520 may transmit a request to release the sidelink to the wireless communication device 530, and the wireless communication device 530 may respond by granting the request or discarding the request.

[0092] Alternatively and / or additionally, the wireless communication device 520 may transmit the indication to the BS 510. The BS 510 may determine that the wireless communication device 520 is no longer a relay UE of the wireless communication device 530. The BS 510 may thus interrupt scheduling resources for the wireless communication device 520 and / or the wireless communication device 530. The BS 510 may select another wireless communication device as a relay UE, or determine that the BS 510 may not use a relay UE at all. As a result, the BS 510 may also save signaling resources.

[0093] As indicated above, Figure 5 is provided as an example. Other examples may be different from the examples described with respect to Figure 5

[0094] Figure 6 is a diagram illustrating an example process 600 performed by a UE, such as a UE, in accordance with the present disclosure. Example process 600 is a UE (e.g., Figure 1 and 2 ​the UE 120 depicted in Figure 3 the wireless communication device 305 depicted in Figure 4 the wireless communication devices 405 and 410 depicted in Figure 5 the wireless communication devices 520 and 530) perform an example of an operation associated with link management of a sidelink.

[0095] As Figure 6 shown in, in some aspects, process 600 may include determining whether a sidelink to another UE is inactive (block 610). For example, a UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282) may determine whether a sidelink to another UE is inactive as described above.

[0096] As Figure 6 further shown in, in some aspects, process 600 may include disabling the sidelink at least in part based on determining that the sidelink is inactive (block 620). For example, a UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282) may disable the sidelink at least in part based on determining that the sidelink is inactive as described above.

[0097] Process 600 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in conjunction with one or more other processes described elsewhere herein.

[0098] In a first aspect, determining whether the sidelink is inactive includes determining whether an inactivity timer on the sidelink meets an inactivity duration threshold, and disabling the sidelink includes disabling the sidelink at least in part based on determining that the timer meets the inactivity duration threshold.

[0099] In a second aspect, alone or in combination with the first aspect, process 600 includes: starting the timer at least in part based on one of: receiving a sidelink data communication or transmitting a sidelink data communication.

[0100] In a third aspect, alone or in combination with one or more of the first and second aspects, process 600 includes: starting the timer at least in part based on one of: receiving a HARQ message or transmitting a HARQ message.

[0101] In a fourth aspect, alone or in combination with one or more of the first through third aspects, process 600 includes: starting the timer at least in part based on one of: receiving a sidelink communication on a PSCCH or transmitting a sidelink communication on the PSCCH.

[0102] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, process 600 includes configuring the inactive duration threshold at least in part based on information received from one of the other UE or the base station.

[0103] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, process 600 includes transmitting a message indicating that the UE is releasing the sidelink.

[0104] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, disabling the sidelink includes disabling the sidelink at least in part based on receiving a grant for the request.

[0105] In an eighth aspect, alone or in combination with one or more of the first to seventh aspects, the request is at least in part based on the prediction that there will be no further communication on the sidelink within a time duration.

[0106] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, disabling the sidelink includes interrupting monitoring of one or more of PSCCH or PSSCH on the sidelink.

[0107] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, disabling the sidelink includes disabling the sidelink at least in part based on receiving the message.

[0108] In an eleventh aspect, alone or in combination with one or more of the first to tenth aspects, process 600 includes transmitting a message granting the request.

[0109] Although Figure 6 illustrates example blocks of process 600, in some aspects, process 600 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks compared to the blocks depicted in Figure 6 . Additionally or alternatively, two or more blocks of process 600 may be executed in parallel.

[0110] Figure 7 is a diagram illustrating an example process 700 performed by a UE, for example, according to the present disclosure. Example process 700 is an example of operations performed by a UE (e.g., Figure 1 and 2 UE 120 depicted in Figure 3 wireless communication device 305 depicted in Figure 4 wireless communication devices 405 and 410 depicted in Figure 5 wireless communication devices 520 and 530 depicted in

[0111] As Figure 7As shown, in some aspects, process 700 may include determining whether the quality of a sidelink to another UE meets a quality threshold (block 710). For example, a UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282) may determine whether the quality of a sidelink to another UE meets a quality threshold, as described above.

[0112] As Figure 7 As further shown, in some aspects, process 700 may include disabling the sidelink at least in part based on determining that the quality of the sidelink does not meet the quality threshold (block 720). For example, a UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282) may disable the sidelink at least in part based on determining that the quality of the sidelink does not meet the quality threshold, as described above.

[0113] Process 700 may include additional aspects, such as any individual aspect or any combination of aspects described below and / or in conjunction with one or more other processes described elsewhere herein.

[0114] In a first aspect, determining whether the quality of the sidelink does not meet the quality threshold includes measuring one or more reference signals from the other UE.

[0115] In a second aspect, alone or in combination with the first aspect, process 700 includes: incrementing a failure count at least in part based on determining that a measurement result does not meet a measurement result threshold, and determining that the quality of the sidelink does not meet the quality threshold at least in part based on determining that the failure count meets a failure count threshold.

[0116] In a third aspect, alone or in combination with one or more of the first and second aspects, determining that the failure count meets the failure count threshold includes determining that the failure count meets the failure count threshold for a specific number of measurement opportunities.

[0117] In a fourth aspect, alone or in combination with one or more of the first to third aspects, process 700 includes: resetting the failure count when a failure count timer expires.

[0118] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, process 700 includes transmitting one or more reference signals for the other UE to measure.

[0119] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, disabling the sidelink includes interrupting the monitoring of one or more of PSCCH or PSSCH.

[0120] In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process 700 includes transmitting a message indicating that the UE is releasing the sidelink with the other UE.

[0121] Although Figure 7 example blocks of process 700 are shown, in some aspects, process 700 may include additional blocks, fewer blocks, different blocks, or blocks arranged differently than those depicted in Figure 7 . Additionally or alternatively, two or more blocks of process 700 may be performed in parallel.

[0122] Figure 8 is a diagram illustrating an example process 800 performed by a UE, for example, in accordance with the present disclosure. Example process 800 is an example of operations performed by a UE (e.g., Figure 1 and 2 the UE 120 depicted in Figure 3 the wireless communication device 305 depicted in Figure 4 the wireless communication devices 405 and 410 depicted in Figure 5 the wireless communication devices 520 and 530 depicted in

[0123] As Figure 8 shown, in some aspects, process 800 may include determining whether an unavailability of a sidelink to another UE meets an unavailability threshold (block 810). For example, a UE (e.g., using the receive processor 258, the transmit processor 264, the controller / processor 280, the memory 282) may determine whether the unavailability of a sidelink to another UE meets the unavailability threshold, as described above.

[0124] As Figure 8 further shown, in some aspects, process 800 may include disabling the sidelink at least in part based on determining that the unavailability of the sidelink meets the unavailability threshold (block 820). For example, a UE (e.g., using the receive processor 258, the transmit processor 264, the controller / processor 280, the memory 282) may disable the sidelink at least in part based on determining that the unavailability of the sidelink meets the unavailability threshold, as described above.

[0125] Process 800 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in combination with one or more other processes described elsewhere herein.

[0126] In a first aspect, determining whether an unavailability of a sidelink meets an unavailability threshold includes performing a LBT procedure on the sidelink and increasing the unavailability at least in part based on a determination that the LBT procedure has failed.

[0127] In a second aspect, either alone or in combination with the first aspect, determining whether the unavailability of the sidelink meets an unavailability threshold includes counting incremental LBT procedure failures and determining that the unavailability of the sidelink meets the unavailability threshold based at least in part on a determination that the count meets a failure count threshold.

[0128] In a third aspect, either alone or in combination with one or more of the first and second aspects, process 800 includes resetting the count when an LBT count timer expires.

[0129] In a fourth aspect, either alone or in combination with one or more of the first through third aspects, disabling the sidelink includes interrupting the monitoring of one or more of the PSCCH or PSSCH.

[0130] In a fifth aspect, either alone or in combination with one or more of the first through fourth aspects, process 800 includes transmitting a message indicating that the UE is releasing the sidelink with the other UE.

[0131] Although Figure 8 example boxes of process 800 are shown, in some aspects, process 800 may include additional boxes, fewer boxes, different boxes, or boxes arranged differently compared to the boxes depicted in Figure 8 . Additionally or alternatively, two or more boxes of process 800 may be executed in parallel.

[0132] Figure 9 is a diagram illustrating an example process 900 performed, for example, by a base station in accordance with the present disclosure. Example process 900 is an example in which a base station (e.g., Figure 1 , 2 and the BS 110 depicted in 4, Figure 5 and the BS 510 depicted in

[0133] As Figure 9 shown, in some aspects, process 900 may include receiving, from a first UE, a message indicating that the first UE is releasing a sidelink with a second UE (block 910). For example, the base station (e.g., using the transmit processor 220, the receive processor 238, the controller / processor 240, the memory 242) may receive, from the first UE, a message indicating that the first UE is releasing a sidelink with a second UE, as described above.

[0134] As Figure 9As further shown, in some aspects, process 900 may include adjusting one or more relay procedures associated with the first UE and the second UE at least in part based on receiving the message (block 920). For example, the base station (e.g., using transmit processor 220, receive processor 238, controller / processor 240, memory 242) may adjust one or more relay procedures associated with the first UE and the second UE at least in part based on receiving the message, as described above.

[0135] Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in connection with one or more other processes described elsewhere herein.

[0136] In a first aspect, adjusting the one or more relay procedures includes deprecating the first UE as a relay UE to the second UE and selecting a third UE having a sidelink to the second UE as a relay to the second UE.

[0137] Although Figure 9 example blocks of process 900 are shown, in some aspects, process 900 may include additional blocks, fewer blocks, different blocks, or blocks arranged differently than those depicted Figure 9 herein. Additionally or alternatively, two or more blocks of process 900 may be executed in parallel.

[0138] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired through practice of the aspects.

[0139] A summary of some aspects of the present disclosure is provided below:

[0140] Aspect 1: A wireless communication method performed by a user equipment (UE), including: determining whether a sidelink to another UE is inactive; and disabling the sidelink at least in part based on determining that the sidelink is inactive.

[0141] The method according to aspect 1, wherein determining whether the sidelink is inactive includes determining whether an inactivity timer on the sidelink meets an inactivity duration threshold, and wherein disabling the sidelink includes disabling the sidelink at least in part based on determining that the timer meets the inactivity duration threshold.

[0142] The method according to aspect 2, further including starting the timer at least in part based on one of the following: receiving sidelink data communication or transmitting sidelink data communication.

[0143] Aspect 4: The method as described in Aspect 2 further includes starting the timer at least partially based on one of the following: receiving a Hybrid Automatic Repeat reQuest (HARQ) message or transmitting an HARQ message.

[0144] Aspect 5: The method as described in Aspect 2 further includes starting the timer at least partially based on one of the following: receiving sidelink communication on a Physical Sidelink Control Channel (PSCCH) or transmitting sidelink communication on the PSCCH.

[0145] Aspect 6: The method as described in Aspect 2 further includes configuring the inactive duration threshold at least partially based on information received from one of the other UE or the base station.

[0146] Aspect 7: The method as described in any of Aspects 1 - 6 further includes: transmitting a message indicating that the UE is releasing the sidelink.

[0147] Aspect 8: The method as described in any of Aspects 1 - 7 further includes: transmitting a message including a request to release the sidelink, and wherein disabling the sidelink includes disabling the sidelink at least partially based on receiving a grant for the request.

[0148] Aspect 9: The method as described in Aspect 8, wherein the request is at least partially based on the prediction that there will be no further communication on the sidelink within a time duration.

[0149] Aspect 10: The method as described in any of Aspects 1 - 9, wherein disabling the sidelink includes interrupting monitoring of one or more of the Physical Sidelink Control Channel or the Physical Sidelink Shared Channel on the sidelink.

[0150] Aspect 11: The method as described in any of Aspects 1 - 10 further includes: receiving a message from the other UE to release the sidelink, and wherein disabling the sidelink includes disabling the sidelink at least partially based on receiving the message.

[0151] Aspect 12: The method as described in any of Aspects 1 - 11 further includes: receiving a request to release the sidelink, and wherein the method includes transmitting a message granting the request.

[0152] Aspect 13: A wireless communication method performed by a User Equipment (UE), including: determining whether the quality of a sidelink to another UE meets a quality threshold; and disabling the sidelink at least partially based on determining that the quality of the sidelink does not meet the quality threshold.

[0153] Aspect 14: The method as described in Aspect 13, wherein determining whether the quality of the sidelink does not meet the quality threshold includes measuring one or more reference signals from the other UE.

[0154] Aspect 15: The method of aspect 14, further comprising: incrementing a failure count at least in part based on a determination that a measurement result does not meet a measurement result threshold, and determining that the quality of the sidelink does not meet the quality threshold at least in part based on a determination that the failure count meets a failure count threshold.

[0155] Aspect 16: The method of aspect 15, wherein determining that the failure count meets the failure count threshold includes determining that the failure count meets the failure count threshold for a specific number of measurement occasions.

[0156] Aspect 17: The method of aspect 15, further comprising: resetting the failure count when a failure count timer expires.

[0157] Aspect 18: The method of any one of aspects 13 - 17, further comprising: transmitting one or more reference signals for measurement by the other UE.

[0158] Aspect 19: The method of any one of aspects 13 - 17, wherein disabling the sidelink includes interrupting monitoring of one or more of a physical sidelink control channel or a physical sidelink shared channel.

[0159] Aspect 20: The method of any one of aspects 13 - 19, further comprising: transmitting a message indicating that the UE is releasing the sidelink with the other UE.

[0160] Aspect 21: A wireless communication method performed by a user equipment (UE), comprising: determining whether an unavailability of a sidelink to another UE meets an unavailability threshold; and disabling the sidelink at least in part based on a determination that the unavailability of the sidelink meets the unavailability threshold.

[0161] Aspect 22: The method of aspect 21, wherein determining whether the sidelink meets the unavailability threshold includes performing a listen - before - talk (LBT) procedure on the sidelink and incrementing the unavailability at least in part based on a determination that the LBT procedure has failed.

[0162] Aspect 23: The method of aspect 21 or 22, wherein determining whether the sidelink meets the unavailability threshold includes incrementing a count of listen - before - talk (LBT) procedure failures and determining that the sidelink meets the unavailability threshold at least in part based on a determination that the count meets a failure count threshold.

[0163] Aspect 24: The method of aspect 23, further comprising: resetting the count when an LBT count timer expires.

[0164] Aspect 25: The method as described in any one of Aspects 21 - 24, wherein disabling the sidelink comprises interrupting monitoring of one or more of a physical sidelink control channel or a physical sidelink shared channel.

[0165] Aspect 26: The method as described in any one of Aspects 21 - 24, further comprising: transmitting a message indicating that the UE is releasing the sidelink with the other UE.

[0166] Aspect 27: A wireless communication method performed by a base station, comprising: receiving, from a first user equipment (UE), a message indicating that the first UE is releasing a sidelink with a second UE; and adjusting, at least in part based on receiving the message, one or more relay procedures associated with the first UE and the second UE.

[0167] Aspect 28: The method as described in Aspect 27, wherein adjusting the one or more relay procedures comprises deprecating the first UE as a relay UE to the second UE, and selecting a third UE having a sidelink to the second UE as a relay to the second UE.

[0168] Aspect 29: An apparatus for wireless communication at a device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the device to perform the method as described in one or more of Aspects 1 - 28.

[0169] Aspect 30: A device for wireless communication, comprising a memory and one or more processors coupled to the memory, the memory and the one or more processors being configured to perform the method as described in one or more of Aspects 1 - 28.

[0170] Aspect 31: A device for wireless communication, comprising at least one means for performing the method as described in one or more of Aspects 1 - 28.

[0171] Aspect 32: A non - transient computer - readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method as described in one or more of Aspects 1 - 28.

[0172] Aspect 33: A non - transient computer - readable medium storing an instruction set for wireless communication, the instruction set comprising one or more instructions that, when executed by one or more processors of a device, cause the device to perform the method as described in one or more of Aspects 1 - 28.

[0173] As used herein, the term "component" is intended to be broadly construed as hardware, firmware, and / or a combination of hardware and software. "Software" shall be broadly construed to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, and / or functions, etc., regardless of whether it is referred to in terms of software, firmware, middleware, microcode, hardware description language, or other terms. As used herein, a processor is implemented in hardware, firmware, and / or a combination of hardware and software.

[0174] It will be apparent that the systems and / or methods described herein can be implemented in various forms of hardware and / or combinations of hardware and software. The actual specific control hardware or software code used to implement these systems and / or methods does not limit the aspects. Thus, the operation and behavior of these systems and / or methods are described herein without reference to specific software code - understanding that software and hardware can be designed to implement these systems and / or methods at least in part based on the description herein.

[0175] As used herein, depending on the context, meeting a threshold may mean a value greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, etc.

[0176] Although specific feature combinations are recited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of the aspects. In fact, many of these features can be combined in ways not specifically recited in the claims and / or not disclosed in the specification. Although each of the dependent claims listed below may directly depend on only one claim, the disclosure of the aspects includes each dependent claim combined with each other claim in this set of claims. As used herein, a phrase that recites "at least one of" a list of items means any combination of those items, including a single member. As an example, "at least one of a, b, or c" is intended to cover: a, b, c, a - b, a - c, b - c, and a - b - c, as well as any combination with multiple identical elements (e.g., a - a, a - a - a, a - a - b, a - a - c, a - b - b, a - c - c, b - b, b - b - b, b - b - c, c - c, and c - c - c, or any other ordering of a, b, and c).

[0177] Elements, acts, or instructions used herein should not be construed as critical or essential unless expressly described as such. Also, as used herein, the articles "a" and "an" are intended to include one or more items and may be used interchangeably with "one or more." Additionally, as used herein, the article "the" is intended to include one or more items referred to in conjunction with the article "the" and may be used interchangeably with "one or more." Further, as used herein, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.) and may be used interchangeably with "one or more." In instances where only one item is intended, the phrase "only one" or similar language is used. Also, as used herein, the terms "having," "including," "containing," etc. are intended to be open-ended terms. Additionally, the phrase "based on" is intended to mean "at least partially based on" unless otherwise expressly stated. Also, as used herein, the term "or" when used in a series is intended to be inclusive and may be used interchangeably with "and / or" unless otherwise expressly stated (e.g., when used in conjunction with "any one of" or "only one of").

Claims

1. A user equipment (UE) for wireless communication, comprising: one or more memories; and one or more processors operatively coupled to the one or more memories, the one or more processors being configured to: determine whether the sidelink is inactive at least in part based on a prediction that there will no longer be communication on the sidelink to another UE over a time duration, the prediction being at least in part based on a traffic pattern on the sidelink at a certain time of day; determine whether the quality of the sidelink meets a quality threshold; determine whether the unavailability of the sidelink meets an unavailability threshold; and disable the sidelink at least in part based on at least two of the following: determining that the sidelink is inactive, determining that the quality of the sidelink fails to meet the quality threshold, or determining that the unavailability of the sidelink meets the unavailability threshold.

2. The UE according to claim 1, wherein: To determine whether the sidelink is inactive, the one or more processors are configured to determine whether an inactivity timer on the sidelink meets an inactivity duration threshold, and to disable the sidelink, the one or more processors are configured to disable the sidelink at least in part based on determining that the timer meets the inactivity duration threshold.

3. The UE of claim 2, wherein the one or more processors are further configured to start the timer at least in part based on one of the following: receiving a sidelink data communication or transmitting a sidelink data communication.

4. The UE of claim 2, wherein the one or more processors are further configured to start the timer at least in part based on one of the following: receiving a sidelink communication on a physical sidelink control channel (PSCCH) or transmitting a sidelink communication on the PSCCH.

5. The UE of claim 2, wherein the one or more processors are further configured to configure the inactivity duration threshold at least in part based on information received from one of the other UE or a network node.

6. The UE of claim 1, wherein the one or more processors are further configured to transmit a message indicating that the UE is releasing the sidelink.

7. The UE according to claim 1, wherein: The one or more processors are further configured to transmit a message including a request to release the sidelink, and to disable the sidelink, the one or more processors are configured to disable the sidelink at least in part based on receiving a grant of the request.

8. The UE of claim 7, wherein the request is at least in part based on a prediction that there will no longer be communication on the sidelink over the time duration.

9. The UE of claim 1, wherein to disable the sidelink, the one or more processors are configured to interrupt monitoring of one or more of a physical sidelink control channel or a physical sidelink shared channel on the sidelink.

10. The UE according to claim 1, wherein: The one or more processors are further configured to receive a message from the other UE to release the sidelink, and to disable the sidelink, the one or more processors are configured to disable the sidelink at least in part based on receiving the message.

11. The UE according to claim 1, wherein the one or more processors are further configured to receive a request to release the sidelink and transmit a message granting the request.

12. A user equipment (UE) for wireless communication, comprising: One or more memories; And One or more processors operatively coupled to the one or more memories, the one or more processors being configured to: Start an inactivity timer on a sidelink to another UE at least in part based on one of: receiving a hybrid automatic repeat request (HARQ) message or transmitting an HARQ message, wherein The timer is configured to be reset by reception indicated by a physical downlink shared channel from a network node; Determine whether the sidelink is inactive at least in part based on whether the timer meets an inactivity duration threshold; Determine whether the quality of the sidelink meets a quality threshold; Determine whether the unavailability of the sidelink meets an unavailability threshold; And Disable the sidelink at least in part based on at least two of the following: Determine that the timer meets the inactivity duration threshold, Determine that the quality of the sidelink fails to meet the quality threshold, or Determine that the unavailability of the sidelink meets the unavailability threshold.

13. The UE according to claim 12, wherein the one or more processors are further configured to transmit a message indicating that the UE is releasing the sidelink.

14. The UE according to claim 12, wherein: The one or more processors are further configured to transmit a message including a request to release the sidelink, and to disable the sidelink, the one or more processors are configured to disable the sidelink at least in part based on receiving a grant of the request.

15. The UE according to claim 14, wherein the request is at least in part based on a prediction that there will be no further communication on the sidelink for a time duration.

16. The UE according to claim 12, wherein to disable the sidelink, the one or more processors are configured to interrupt monitoring of one or more of a physical sidelink control channel or a physical sidelink shared channel on the sidelink.

17. The UE according to claim 12, wherein: The one or more processors are further configured to receive a message from the other UE to release the sidelink, and to disable the sidelink, the one or more processors are configured to disable the sidelink at least in part based on receiving the message.

18. The UE according to claim 12, wherein the one or more processors are further configured to receive a request to release the sidelink and transmit a message granting the request.

19. A method for wireless communication at a user equipment (UE), comprising: Determine whether the sidelink is inactive by predicting, at least in part based on the UE, whether there will no longer be communication on the sidelink to another UE over a period of time, the prediction being at least in part based on the traffic pattern on the sidelink at a certain time of day; Determine whether the quality of the sidelink meets a quality threshold; Determine whether the unavailability of the sidelink meets an unavailability threshold; And Disable the sidelink at least in part based on at least two of the following: Determine that the sidelink is inactive, Determine that the quality of the sidelink fails to meet the quality threshold, or Determine that the unavailability of the sidelink meets the unavailability threshold.

20. The method according to claim 19, wherein: Determining whether the sidelink is inactive includes determining whether an inactivity timer on the sidelink meets an inactivity duration threshold, and disabling the sidelink includes disabling the sidelink at least in part based on determining that the timer meets the inactivity duration threshold.

21. The method of claim 20, further comprising starting the timer at least in part based on one of the following: receiving sidelink data communication or transmitting sidelink data communication.

22. The method of claim 20, further comprising starting the timer at least in part based on one of the following: receiving sidelink communication on a physical sidelink control channel (PSCCH) or transmitting sidelink communication on the PSCCH.

23. The method according to claim 20, further comprising: Configure the inactivity duration threshold at least in part based on information received from one of the other UE or the network node.

24. The method according to claim 19, further comprising: Transmit a message indicating that the UE is releasing the sidelink.

25. The method according to claim 19, further comprising: Transmit a message including a request to release the sidelink, wherein disabling the sidelink is at least in part based on receiving a grant for the request.

26. The method according to claim 19, wherein disabling the sidelink comprises: Interrupt monitoring one or more of the physical sidelink control channel or the physical sidelink shared channel on the sidelink.

27. The method according to claim 19, further comprising: Receive a message from the other UE to release the sidelink, wherein disabling the sidelink is at least in part based on receiving the message.

28. A method for wireless communication at a user equipment (UE), comprising: Start an inactivity timer on a sidelink to another UE at least in part based on one of the following: receiving a hybrid automatic repeat request (HARQ) message or transmitting an HARQ message, wherein the timer is configured to be reset by reception indicated by a physical downlink shared channel from a network node; Determine whether the sidelink is inactive at least in part based on whether the timer meets an inactivity duration threshold; Determine whether the quality of the sidelink meets a quality threshold; Determine whether the unavailability of the sidelink meets an unavailability threshold; And Disable the sidelink at least in part based on at least two of the following: Determine that the timer meets the inactivity duration threshold, Determine that the quality of the sidelink fails to meet the quality threshold, or Determine that the unavailability of the sidelink meets the unavailability threshold.

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