Techniques for Sidelink Synchronization Signal Transmission for Multi-Transmission / Reception Point (TRP) User Equipment (UE)

Abstract

Methods, systems, and devices for wireless communication are described. A first user equipment (UE) may receive a first sidelink synchronization signal (SLSS) from a second UE at a first transmission reception point (TRP) and a second TRP different from the first TRP. The first UE may perform a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. The first UE may then send a second SLSS to a third UE at least partially based on the first set of measurements, the second set of measurements, or both meeting one or more measurement thresholds.

Description

Technical Field

[0001] Broadly speaking, the following relates to wireless communication, and more specifically, to techniques for sidelink synchronization signal transmission to a multi-transmission reception point (TRP) user equipment (UE). Background Art

[0002] Wireless communication systems have been widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasting, and so on. These systems are capable of supporting communication with multiple users by sharing available system resources such as time, frequency, and power. Examples of such multi-access systems include fourth-generation (4G) systems (e.g., Long-Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems) and fifth-generation (5G) systems (which may be referred to as New Radio (NR) systems). These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multi-access communication system may include one or more base stations or one or more network access nodes, each of which supports communication with multiple communication devices (or may be referred to as user equipment (UE)) simultaneously.

[0003] In some wireless communication systems, wireless devices such as user equipment (UE) may exchange sidelink synchronization signals (SLSS) with each other so that each UE can coordinate its internal timer and synchronize it with the network and other UEs within the network. Additionally, each UE may determine whether each UE should relay (e.g., transmit) the SLSS to other UEs within the system based on certain characteristics associated with the received SLSS (e.g., power, quality). Summary of the Invention

[0004] The described technology relates to improved methods, systems, devices, and apparatuses for techniques that support sidelink synchronization signal (SLSS) transmission for a multi-transmission reception point (TRP) user equipment (UE). In some aspects, a first UE (e.g., a multi-TRP UE) may perform measurements on SLSS received at a first TRP and a second TRP. The first UE may then determine whether to transmit (e.g., relay) the SLSS based on whether the measurements performed on the SLSS received at the first TRP and the second TRP meet one or more thresholds. For example, the first UE may compare both a first set of measurements performed at the first TRP and a second set of measurements performed at the second TRP with a single measurement threshold, and may relay the SLSS if at least one set of measurements meets (e.g., is less than) the measurement threshold (e.g., relay if RSRP < Thresh RSRP , then relay). Specifically, the first UE may relay the SLSS via both TRPs or via only the TRP associated with the measurements that meet the measurement threshold.

[0005] In other cases, the first UE may compare the sets of measurements performed at each TRP with multiple thresholds. For example, if the measurement result is below a first measurement threshold (e.g., a lower bound measurement threshold), the first UE may start a timer. In this example, if the measurement result rises above a second measurement threshold (e.g., an upper bound measurement threshold) before the timer expires, the first UE may deactivate the timer and avoid relaying the SLSS. Conversely, if the timer expires before the second measurement threshold is met, the first UE may determine to relay the SLSS. The multiple thresholds may be applied combinatorially to both TRPs, applied individually to each TRP, or both. In some cases, the measurement results performed at each TPR may be used to determine the beam direction of the received SLSS such that the relayed SLSS may be transmitted along the same (or similar) beam direction. By implementing efficient reception and transmission of SLSS in the context of a multi-TRP UE, the efficiency and effectiveness of wireless communication within the network can be improved.

[0006] A method for wireless communication at a first UE is described. The method may include: receiving a first SLSS from a second UE at a first transmission reception point (TRP) and a second TRP different from the first TRP; performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP; and transmitting a second SLSS to a third UE based on the first set of measurements, the second set of measurements, or both meeting one or more measurement thresholds.

[0007] Describes an apparatus for wireless communication at a first UE. The apparatus may include a processor, a memory in electrical communication with the processor, and instructions stored in the memory. The instructions may be executed by the processor to cause the apparatus to: receive a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP; perform a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP; and send a second SLSS to a third UE based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

[0008] Describes another apparatus for wireless communication at a first UE. The apparatus may include: a unit for receiving a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP; a unit for performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP; and a unit for sending a second SLSS to a third UE based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

[0009] Describes a non-transitory computer-readable medium storing code for wireless communication at a first UE. The code may include instructions executable by a processor to: receive a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP; perform a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP; and send a second SLSS to a third UE based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

[0010] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for: determining that the first set of measurements fails to meet the one or more measurement thresholds; determining that the second set of measurements meets the one or more measurement thresholds; and using the second TRP to send the second SLSS based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

[0011] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include: operations, features, units, or instructions for avoiding using the first TRP to send the second SLSS based on determining that the first set of measurements fails to meet the one or more measurement thresholds.

[0012] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for using the first TRP to transmit the second SLSS based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

[0013] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the first set of measurements, the second set of measurements, or both include received signal strength indicator (RSSI) measurements, reference signal received power (RSRP) measurements, reference signal received quality (RSRQ) measurements, or any combination thereof.

[0014] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the one or more measurement thresholds include an RSSI threshold, an RSRP threshold, an RSRQ threshold, or any combination thereof, and the first set of measurements, the second set of measurements, or both meet the corresponding measurement thresholds if the first set of measurements, the second set of measurements, or both may be less than or equal to the corresponding measurement threshold.

[0015] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: determining that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds; starting one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold; and determining expiration of the one or more timers based on starting the one or more timers, wherein transmitting the second SLSS may be based on determining expiration of the one or more timers.

[0016] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, starting the one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold may include operations, features, units, or instructions for: starting a first timer associated with the first TRP based on determining that the first set of measurements meets the first measurement threshold; starting a second timer associated with the second TRP based on determining that the second set of measurements meets the first measurement threshold.

[0017] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, transmitting the second SLSS may include operations, features, units, or instructions for: transmitting the second SLSS using the first TRP based on determining an expiration of the first timer associated with the first TRP; transmitting the second SLSS using the second TRP based on determining an expiration of the second timer associated with the second TRP.

[0018] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for: determining that the first set of measurements, the second set of measurements, or both meet a first measurement threshold of the one or more measurement thresholds; starting one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold; deactivating the one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet a second measurement threshold of the one or more measurement thresholds, the second measurement threshold being different from the first measurement threshold; and avoiding transmitting the second SLSS based on deactivating the one or more timers.

[0019] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for determining a resource set associated with the first SLSS, the second SLSS, or both, wherein transmitting the second SLSS may be based on determining the resource set.

[0020] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for: receiving the first SLSS using a first subset of the resource set based on determining the resource set; and transmitting the second SLSS using a second subset of the resource set that is different from the first subset based on determining the resource set.

[0021] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for receiving a control message from a base station that includes an indication of the resource set, wherein determining the resource set may be based on receiving the control message.

[0022] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, transmitting the second SLSS may include operations, features, elements, or instructions for: transmitting the second SLSS according to the resource set using a TRP selected from the first TRP and the second TRP; and transmitting a null value according to the resource set using the first TRP or the second TRP that may be different from the selected TRP.

[0023] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, elements, or instructions for estimating a beam direction of the first SLSS based on the first set of measurements and the second set of measurements, wherein the second SLSS may be transmitted based on the estimated beam direction.

[0024] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, elements, or instructions for transmitting the second SLSS along a second beam direction that may be equal to the estimated beam direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Examples of wireless communication systems that support techniques for sidelink synchronization signal (SLSS) transmission to a multi-transmission reception point (TRP) user equipment (UE) in accordance with aspects of the present disclosure are shown.

[0026] Figure 2 Examples of wireless communication systems that support techniques for SLSS transmission to a multi-TRP UE in accordance with aspects of the present disclosure are shown.

[0027] Figure 3 Examples of wireless communication systems that support techniques for SLSS transmission to a multi-TRP UE in accordance with aspects of the present disclosure are shown.

[0028] Figure 4 Examples of process flows that support techniques for SLSS transmission to a multi-TRP UE in accordance with aspects of the present disclosure are shown.

[0029] Figure 5 and Figure 6 Examples of block diagrams of devices that support techniques for SLSS transmission to a multi-TRP UE in accordance with aspects of the present disclosure are shown.

[0030] Figure 7 Examples of block diagrams of communication managers that support techniques for SLSS transmission to a multi-TRP UE in accordance with aspects of the present disclosure are shown.

[0031] Figure 8Aspects of the present disclosure are directed to a diagram of a system including an apparatus supporting techniques for sidelink synchronization signal (SLSS) transmission with a multi-TRP UE.

[0032] Figures 9 to 11 Aspects of the present disclosure are directed to a flowchart depicting a method for supporting techniques for SLSS transmission with a multi-TRP UE. DETAILED DESCRIPTION

[0033] In some wireless communication systems, wireless devices such as user equipment (UE) may exchange sidelink synchronization signals (SLSS) with each other so that individual UEs can coordinate their internal timers and synchronize them with the network and other UEs within the network. For example, a first UE that cannot directly receive timing information from a network (e.g., a base station, a satellite) may receive an SLSS from a second UE (e.g., a synchronization reference (SyncRef) UE). The first UE can then use the received SLSS to coordinate and synchronize its internal timer. Additionally, the first UE can determine whether the first UE should "relay" the received SLSS to other UEs within the network (e.g., determine whether it should become a SyncRef UE). The first UE can determine whether to relay the SLSS to other UEs based on the strength of the received SLSS (e.g., received signal strength indicator (RSSI), reference signal received power (RSRP), reference signal received quality (RSRQ)). For example, if the strength of the received SLSS (e.g., RSRP) is higher than a given threshold (e.g., RSRP > Thresh RSRP ), the first UE can determine that the SLSS is strong enough to reach other UEs within the system and can thus avoid relaying the SLSS. Conversely, if the strength of the received SLSS is lower than a given threshold (e.g., RSRP < Thresh RSRP ), the first UE can determine that the SLSS may not be strong enough to reach other UEs within the system and can thus determine to relay the SLSS to other UEs.

[0034] However, in the case of a UE with multiple transmission reception points (TRP), the measured strength of the received SLSS may vary significantly between TRPs. For example, a 16-wheel semi-trailer truck may include two separate TRPs that are approximately 20 meters apart, which may result in significant differences in the measured SLSS strength. In the case of a multi-TRP UE, these varying SLSS strengths may significantly complicate the determination of whether the UE should relay the SLSS. Additionally, traditional techniques do not enable a multi-TRP to determine whether all TRPs should relay the SLSS or only a subset of these TRPs.

[0035] To improve wireless communication in the context of SLSS transmission and reception, techniques for SLSS transmission and reception with a multi-TRP UE are disclosed. In some aspects, a first UE (e.g., a multi-TRP UE) may perform measurements (e.g., RSSI measurement, RSRP measurement, RSRQ measurement) on SLSS received at a first TRP and a second TRP. The first UE may then determine whether to transmit (e.g., relay) the SLSS based on whether the measurements performed on the SLSS received at the first TRP and the second TRP meet one or more thresholds (e.g., an RSSI threshold, an RSRP threshold, an RSRQ threshold). For example, the first UE may compare both a first set of measurements performed at the first TRP and a second set of measurements performed at the second TRP with a single measurement threshold, and may relay the SLSS if at least one set of measurements meets (e.g., is less than) the measurement threshold (e.g., relay if RSRP < Thresh RSRP , then relay). Specifically, the first UE may relay the SLSS via two TRPs or only via the TRP associated with the measurements that meet the measurement threshold.

[0036] In other cases, the first UE may compare the sets of measurements performed at each TRP with multiple thresholds. For example, if the measurement result is below a first measurement threshold (e.g., a lower bound measurement threshold), the first UE may start a timer. In this example, if the measurement result rises above a second measurement threshold (e.g., an upper bound measurement threshold) before the timer expires, the first UE may deactivate the timer and avoid relaying the SLSS. Conversely, if the timer expires before the second measurement threshold is met, the first UE may determine to relay the SLSS. The multiple thresholds may be applied combinatorially to the two TRPs, applied individually to each TRP, or both. In some cases, the measurement results performed at each TPR may be used to determine the beam direction of the received SLSS such that the relayed SLSS may be transmitted along the same (or a similar) beam direction. By implementing efficient reception and transmission of SLSS in the context of a multi-TRP UE, the efficiency and effectiveness of wireless communication within the network can be improved.

[0037] Aspects of the present disclosure are initially described in the context of a wireless communication system. Other aspects of the present disclosure are described in the context of an exemplary process flow. Aspects of the present disclosure are further depicted and described by way of and with reference to apparatus diagrams, system diagrams, and flowcharts related to techniques for SLSS transmission with a multi-TRP UE.

[0038] Figure 1In aspects of the present disclosure, an example of a wireless communication system 100 that supports techniques for SLSS transmission with a multi-TRP UE is shown. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long-Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communication, ultra-reliable (e.g., mission-critical) communication, low-latency communication, communication with low-cost and low-complexity devices, or any combination thereof.

[0039] The base stations 105 may be dispersed throughout a geographic area to form the wireless communication system 100, and may be devices of different forms or having different capabilities. The base stations 105 and the UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110, and the UEs 115 and the base stations 105 may establish one or more communication links 125 over the coverage area 110. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 can support the transmission of signals according to one or more radio access technologies.

[0040] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices of different forms or having different capabilities. In Figure 1 some example UEs 115 are shown. The UEs 115 described herein are capable of communicating with various types of devices such as other UEs 115, base stations 105, or network devices (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network devices), as Figure 1 shown in

[0041] The base stations 105 may communicate with the core network 130, or with each other, or both. For example, the base stations 105 may interact with the core network 130 via one or more backhaul links 155 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 may communicate directly (e.g., directly between the base stations 105) or indirectly (e.g., through the core network 130), or both, with each other via the backhaul links 155 (e.g., via X2, Xn, or other interfaces). In some examples, the backhaul links 155 may be or include one or more wireless links.

[0042] One or more of the base stations 105 described herein may include or be referred to by those of ordinary skill in the art as: base station transceivers, radio base stations, access points, radio transceivers, Node Bs, eNodeBs (eNBs), next-generation Node Bs or giga Node Bs (any of which may be referred to as gNBs), home Node Bs, home eNodeBs, or other suitable terms.

[0043] The UE 115 may include or may be referred to as a mobile device, wireless device, remote device, handheld device, or user equipment, or some other suitable term, where the "device" may also be referred to as a unit, station, terminal, or client, etc. The UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, personal digital assistant (PDA), tablet computer, laptop computer, or personal computer. In some examples, the UE 115 may include or may be referred to as a wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, or machine type communication (MTC) device, etc., which may be implemented in various items such as home appliances, or vehicles, meters, etc.

[0044] The UE 115 described herein is capable of communicating with various types of devices, such as other UEs 115 that sometimes act as relays, as well as the base station 105 and network devices including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, and other examples, such as Figure 1 as shown.

[0045] The UE 115 and the base station 105 may communicate wirelessly with each other via one or more carriers over one or more communication links 125. The term "carrier" may refer to a set of radio spectrum resources having a defined physical layer structure to support the communication link 125. For example, a carrier for the communication link 125 may include a portion (e.g., a bandwidth part (BWP)) of a radio spectrum band that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling to coordinate the operation of the carrier, user data, or other signaling. The wireless communication system 100 may use carrier aggregation or multi-carrier operation to support communication with the UE 115. According to a carrier aggregation configuration, the UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used with frequency division duplex (FDD) and time division duplex (TDD) component carriers.

[0046] The communication link 125 shown in the wireless communication system 100 may include an uplink transmission from the UE 115 to the base station 105, or a downlink transmission from the base station 105 to the UE 115. A carrier may carry downlink or uplink communication (e.g., in FDD mode) or may be configured to carry both downlink and uplink communication (e.g., in TDD mode).

[0047] A carrier may be associated with a particular bandwidth of the radio spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or the wireless communication system 100. For example, the carrier bandwidth may be one of a plurality of defined bandwidths of a carrier of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)). Devices of the wireless communication system 100 (e.g., the base station 105, the UE 115, or both) may have a hardware configuration that supports communication on a particular carrier bandwidth or may be configurable to support communication on one of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 or a UE 115 that supports simultaneous communication via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate on a portion (e.g., a subband, a BWP) or all of the carrier bandwidth.

[0048] The signal waveform transmitted over a carrier may be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM)). In a system employing an MCM technique, a resource element may include a symbol period (e.g., the duration of a modulated symbol) and a subcarrier, where the symbol period and the subcarrier spacing are inversely proportional. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Thus, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate of the UE 115. Wireless communication resources may refer to radio spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase the data rate or data integrity for communicating with the UE 115.

[0049] A carrier may support one or more numerologies, where a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs having the same or different numerologies. In some examples, the UE 115 may be configured with multiple BWPs. In some examples, a single BWP of a carrier may be active at a given time, and the communication of the UE 115 may be restricted to one or more active BWPs.

[0050] The time intervals for the base station 105 or the UE 115 can be expressed as multiples of a basic time unit (e.g., it can refer to a sampling period of T s = 1 / (Δf max ·N f ), where Δf max can represent the maximum supported subcarrier spacing and N f can represent the maximum supported discrete Fourier transform (DFT) size. The time intervals of the communication resources can be organized according to radio frames, where each radio frame has a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a system frame number (SFN) (e.g., in the range from 0 to 1023).

[0051] Each frame can include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot can have the same duration. In some examples, a frame can be divided (e.g., in the time domain) into subframes, and each subframe can be further divided into a plurality of time slots. Alternatively, each frame can include a variable number of time slots, and the number of time slots can depend on the subcarrier spacing. Each time slot can include a plurality of symbol periods (e.g., depending on the length of the cyclic prefix appended to each symbol period). In some wireless communication systems 100, a time slot can be further divided into a plurality of mini-slots containing one or more symbols. In addition to the cyclic prefix, each symbol period can contain one or more (e.g., N f ) sampling periods. The duration of the symbol period can depend on the subcarrier spacing or the operating frequency band.

[0052] A subframe, time slot, mini-slot, or symbol can be the smallest scheduling unit of the wireless communication system 100 (e.g., in the time domain), which can be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in the TTI) can be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 can be dynamically selected (e.g., in a burst of shortened TTIs (sTTIs)).

[0053] Physical channels can be multiplexed on a carrier according to various techniques. For example, time-division multiplexing (TDM) techniques, frequency-division multiplexing (FDM) techniques, or one or more of hybrid TDM-FDM techniques can be used to multiplex physical control channels and physical data channels on a downlink carrier. A control region for a physical control channel (e.g., a control resource set (CORESET)) can be defined by multiple symbol periods and can extend over the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) can be configured for a group of UEs 115. For example, one or more of the UEs 115 can monitor or search a control region for control information according to one or more search space sets, and each search space set can include one or more control channel candidates having one or more aggregation levels arranged in a cascaded manner. The aggregation level for a control channel candidate can refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with the coded information for a control information format having a given payload size. The search space set can include a common search space set configured to send control information to multiple UEs 115 and a UE-specific search space set for sending control information to a specific UE 115.

[0054] Each base station 105 can provide communication coverage via one or more cells (e.g., macro cells, small cells, hotspots, or other types of cells or any combination thereof). The term "cell" can refer to a logical communication entity for communication with a base station 105 (e.g., via a carrier) and can be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), etc.) for distinguishing adjacent cells. In some examples, a cell can also refer to a geographic coverage area 110 or a portion of the geographic coverage area 110 (e.g., a sector) on which the logical communication entity operates. Depending on various factors (e.g., the capabilities of the base station 105), such a cell can range from a smaller area (e.g., a structure, a subset of a structure) to a larger area. For example, a cell can be or include a building, a subset of a building, or an external space between or overlapping with the geographic coverage area 110, etc.

[0055] Macro cells typically cover a relatively large geographical area (e.g., a radius of several kilometers), which allows unrestricted access for UEs 115 having a service subscription with a network provider that supports the macro cell. In contrast to macro cells, small cells can be associated with low-power base stations 105 and can operate in the same or a different (e.g., licensed, unlicensed) frequency band as the macro cell. Small cells can provide unrestricted access to UEs 115 having a service subscription with a network provider, or can provide restricted access to UEs 115 associated with the small cell (e.g., UEs 115 in a closed subscriber group (CSG), UEs 115 associated with users in a home or office). Base station 105 can support one or more cells and can also support communication on one or more cells using one or more component carriers.

[0056] In some examples, base station 105 can be movable and thus provides communication coverage for a mobile geographical coverage area 110. In some examples, different geographical coverage areas 110 associated with different technologies can overlap, but different geographical coverage areas 110 can be supported by the same base station 105. In other examples, overlapping geographical coverage areas 110 associated with different technologies can be supported by different base stations 105. For example, wireless communication system 100 can include a heterogeneous network in which different types of base stations 105 use the same or different radio access technologies to provide coverage for various geographical coverage areas 110.

[0057] Wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication or various combinations thereof. For example, wireless communication system 100 can be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. UE 115 can be designed to support ultra-reliable, low-latency, or critical functions (e.g., mission-critical functions). Ultra-reliable communication can include private communication or group communication and can be supported by one or more mission-critical services (e.g., mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData)). Support for mission-critical functions can include prioritizing services, and mission-critical services can be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency can be used interchangeably herein.

[0058] In some examples, UE 115 is also capable of communicating directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., using peer-to-peer (P2P) or D2D protocols). One or more UEs 115 using D2D communication may be located within the geographic coverage area 110 of base station 105. Other UEs 115 in the group may be located outside the geographic coverage area 110 of base station 105 or may not be able to receive transmissions from base station 105. In some examples, the group of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system in which each UE 115 transmits signals to each other UE 115 in the group. In some examples, base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving base station 105.

[0059] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), the latter of which may include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management function (AMF)), and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)). The control plane entity may manage non-access stratum (NAS) functions, such as the mobility, authentication, and bearer management of UEs 115 served by base station 105 associated with core network 130. User IP packets may be transported through the user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to network operator IP services 150. These operator IP services 150 may include access to the Internet, an intranet, an IP multimedia subsystem (IMS), or packet-switched streaming services.

[0060] Some of the network devices (e.g., base station 105) may include sub-components such as access network entity 140, which may be examples of access node controllers (ANC). Each access network entity 140 may communicate with UE 115 via one or more other access network transmission entities 145 (which may be referred to as radio heads, intelligent radio heads, or transmission / reception points (TRP)). Each access network transmission entity 145 may include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANC), or may be combined in a single network device (e.g., base station 105).

[0061] The wireless communication system 100 may operate using one or more frequency bands (generally in the range of 300 megahertz (MHz) to 300 gigahertz (GHz)). Generally, the region from 300 MHz to 3 GHz is called the ultra-high frequency (UHF) region or the decimeter band, due to its wavelength range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, however, these waves can penetrate structures sufficiently to provide service to UEs 115 located indoors. Compared to transmissions at smaller frequencies and longer wavelengths using the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz, UHF wave transmissions may be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers).

[0062] The wireless communication system 100 may also operate in the super-high frequency (SHF) region using a frequency band from 3 GHz to 30 GHz (which is also called the centimeter band), or in the extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) (this region is also called the millimeter band). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communication between UE 115 and base station 105, and the EHF antennas of the corresponding devices may be even smaller and more compact than UHF antennas. In some examples, this may facilitate the use of antenna arrays within the device. However, compared to SHF or UHF transmissions, EHF transmissions may suffer from greater atmospheric attenuation and shorter transmission distances. In transmissions using one or more different frequency regions, the techniques disclosed herein may be employed, and the specified use of frequency bands across these frequency regions may vary due to national or regulatory authorities.

[0063] The wireless communication system 100 can utilize licensed and unlicensed radio spectrum bands. For example, the wireless communication system 100 can employ Licensed-Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology in unlicensed bands such as the 5 GHz Industrial, Scientific, and Medical (ISM) band. When operating in an unlicensed radio spectrum band, devices such as the base station 105 and the UE 115 can employ carrier sensing to achieve collision detection and avoidance. In some examples, operation in the unlicensed band can be based on a carrier aggregation configuration that combines component carriers operating in a licensed band (e.g., LAA). Operations in the unlicensed spectrum can include other examples such as downlink transmission, uplink transmission, P2P transmission, or D2D transmission.

[0064] The base station 105 or the UE 115 can be equipped with multiple antennas, which can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of the base station 105 or the UE 115 can be located in one or more antenna arrays or antenna panels, which can support MIMO operation or transmit beam or receive beamforming. For example, one or more base station antennas or antenna arrays can be co-located at an antenna assembly (e.g., an antenna tower). In some examples, the antennas or antenna arrays associated with the base station 105 can be located at different geographical locations. The base station 105 can have an antenna array with multiple rows and columns of antenna ports, and the base station 105 can use this antenna array to support beamforming for communication with the UE 115. Similarly, the UE 115 can have one or more antenna arrays, which can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel can support radio frequency beamforming for signals transmitted via the antenna ports.

[0065] The base station 105 or the UE 115 can use MIMO communication to utilize multipath signal propagation and increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers. These techniques can be referred to as spatial multiplexing. For example, the transmitting device can transmit the multiple signals via different antennas or different combinations of antennas. Similarly, the receiving device can receive the multiple signals via different antennas or different combinations of antennas. Each of the multiple signals can be referred to as a separate spatial stream and can carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers can be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO), where under SU-MIMO, multiple spatial layers are transmitted to the same receiving device, and under MU-MIMO, multiple spatial layers are transmitted to multiple devices.

[0066] Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., base station 105, UE 115) to shape or control an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals transmitted via the antenna elements of an antenna array such that certain signals propagating in a particular azimuth with respect to the antenna array experience constructive interference while other signals experience destructive interference. The adjustment of the signals transmitted via the antenna elements can include: the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to the signals carried by the antenna elements associated with the device. The adjustment associated with each antenna element can be specified by a set of beamforming weights associated with a particular azimuth (e.g., with respect to the antenna array of the transmitting device or the receiving device, or with respect to some other azimuth).

[0067] The base station 105 or the UE 115 can use beam scanning techniques as part of a beamforming operation. For example, the base station 105 can use multiple antennas or antenna arrays (e.g., antenna panels) to perform a beamforming operation to communicate directionally with the UE 115. The base station 105 can transmit some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) multiple times in different directions. For example, the base station 105 can transmit signals according to different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions can be used to identify (e.g., by a transmitting device such as the base station 105 or a receiving device such as the UE 115) the beam direction for later transmission or reception by the base station 105.

[0068] The base station 105 can transmit some signals (e.g., data signals associated with a particular receiving device) in a single beam direction (e.g., a direction associated with a receiving device such as the UE 115). In some examples, the beam direction associated with a transmission in a single beam direction can be determined based on signals transmitted in one or more beam directions. For example, the UE 115 can receive one or more of the signals transmitted by the base station 105 in different directions and can report to the base station 105 an indication of the signal that the UE 115 receives with the highest signal quality or other acceptable signal quality.

[0069] In some examples, multiple beam directions may be used to perform transmissions by a device (e.g., base station 105 or UE 115), and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from base station 105 to UE 115). UE 115 may report feedback indicating precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across the system bandwidth or one or more subbands. Base station 105 may transmit reference signals (e.g., cell-specific reference signal (CRS), channel state information reference signal (CSI-RS)), which may be precoded or non-precoded. UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., multi-panel type codebook, linear combination type codebook, port selection type codebook). Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 may employ similar techniques to transmit signals multiple times in different directions (e.g., to identify beam directions for subsequent transmissions or receptions by UE 115) or to transmit signals in a single direction (e.g., for sending data to a receiving device).

[0070] When receiving various signals from base station 105 (e.g., synchronization signals, reference signals, beam selection signals, or other control signals), a receiving device (e.g., UE 115) may attempt multiple receiving configurations (e.g., directional listening). For example, the receiving device may attempt multiple receiving directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (e.g., different direction listening weight sets) (where these weight sets are applied to signals received at multiple antenna elements of an antenna array), or by processing received signals according to different receive beamforming weight sets (where these weight sets are applied to signals received at multiple antenna elements of an antenna array), any of which may be referred to as "listening" according to different receiving configurations or receiving directions. In some examples, the receiving device may use a single receiving configuration to receive along a single beam direction (e.g., when receiving a data signal). The single receiving configuration may be aligned in a beam direction determined based on listening according to different receiving configuration directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio (SNR), highest signal-to-interference-plus-noise ratio (SINR), or otherwise acceptable signal quality based on listening according to multiple beam directions).

[0071] The wireless communication system 100 can be a packet-based network operating according to a layered protocol stack. In the user plane, the communication of the bearer or Packet Data Convergence Protocol (PDCP) layer can be IP-based. The Radio Link Control (RLC) layer can perform packet segmentation and reassembly for communication over logical channels. The Medium Access Control (MAC) layer can perform priority handling and multiplexing of logical channels to transport channels. The MAC layer can also use error detection techniques, error correction techniques, or both to support retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer can provide the establishment, configuration, and maintenance of the RRC connection between the UE 115 and the base station 105 or the core network 130 that supports the radio bearers for user plane data. In the physical layer, the transport channels can be mapped to physical channels.

[0072] The UE 115 and the base station 105 can support retransmission of data to increase the likelihood of successfully receiving the data. Hybrid Automatic Repeat Request (HARQ) feedback is a technique for increasing the likelihood of correctly receiving data over the communication link 125. HARQ can include a combination of error correction (e.g., using Cyclic Redundancy Check (CRC)), Forward Error Correction (FEC), and retransmission (e.g., Automatic Repeat Request (ARQ)). HARQ can improve the throughput of the MAC layer under poor radio conditions (e.g., low signal-to-noise ratio conditions). In some examples, the device can support same-slot HARQ feedback, in which case the device can provide HARQ feedback in the same slot for data received in a previous symbol of the specific slot. In other cases, the device can provide HARQ feedback in a subsequent slot or according to some other time interval.

[0073] The wireless communication system 100 can also include one or more satellites 120. The satellites 120 can communicate with the base station 105 and the UE 115, the base station 105 can be referred to as a gateway in the non-terrestrial network, and the UE 115 can include other high-altitude or ground communication devices. In some examples, the satellite 120 itself can be an example of the base station 105. The satellite 120 can be any suitable type of communication satellite configured to relay or otherwise support communication between different devices in the wireless communication system 100. The satellite 120 can be an example of a space satellite, balloon, airship, airplane, drone, unmanned aerial vehicle, or other aircraft that can support communication from a generally non-terrestrial, overhead, or high-altitude position. In some examples, the satellite 120 can be in a geosynchronous or geostationary orbit, a low Earth orbit, or a medium Earth orbit. The satellite 120 can be a multi-beam satellite configured to provide service to multiple service beam coverage areas within a configured geographic service area. The satellite 120 can be at any distance from the Earth's surface or other reference surface.

[0074] In some examples, as part of a non-terrestrial network, a cell may be provided or established by satellite 120. In some cases, satellite 120 may perform the functions of base station 105, act as a bent pipe satellite, or act as a regenerative satellite, or a combination thereof. In some examples, satellite 120 may be an example of an intelligent satellite or a satellite with intelligent or other communication processing capabilities. For example, an intelligent satellite may be configured to perform more functions than a regenerative satellite (e.g., may be configured to perform specific algorithms in addition to the algorithms used in a regenerative satellite for reprogramming). In a bent pipe transponder configuration, satellite 120 may be configured to receive signals from a ground station (e.g., a gateway, base station 105, core network 130) and send these signals to different ground stations or terminals (e.g., UE 115, base station 105). In some cases, satellite 120 supporting a bent pipe transponder configuration may amplify the signals or convert from an uplink frequency to a downlink frequency. In some examples, satellite 120 supporting a regenerative transponder configuration may relay signals in the same way as a bent pipe transponder configuration, but may also use on-board processing to perform other functions. Examples of these other functions may include: demodulating received signals, decoding received signals, re-encoding signals to be sent, or modulating signals to be sent, or a combination thereof. In some examples, satellite 120 supporting a bent pipe transponder configuration or a regenerative transponder configuration may receive signals from base station 105 and may relay the signals to UE 115 or base station 105, or vice versa.

[0075] UE 115 of wireless communication system 100 may support techniques for SLSS transmission and reception. Specifically, UE 115 of the wireless communication system may facilitate the transmission and reception of SLSS in the context of a multi-TRP UE 115. Specifically, the techniques described herein may enable a multi-TRP UE 115 of wireless communication system 100 to efficiently and effectively determine whether each multi-TRP UE 115 should relay a received SLSS to other UEs 115 in wireless communication system 100. Additionally, in the case where a multi-TRP UE 115 determines that it can relay SLSS, the techniques described herein may enable the multi-TRP UE 115 to determine which TRP the multi-TRP UE 115 should use to transmit (e.g., relay) the SLSS.

[0076] For example, a first UE 115 (e.g., a multi-TRP UE 115) of the wireless communication system 100 may receive an SLSS from a second UE 115 (e.g., a SyncRef UE 115) of the wireless communication system 100. The first UE 115 may perform measurements (e.g., RSSI measurement, RSRP measurement, RSRQ measurement) on the SLSS received at the first TRP and the second TRP of the first UE 115. Then, the first UE 115 may determine whether to transmit (e.g., relay) the SLSS based on whether the measurements performed on the SLSS received at the first TRP and the second TRP meet one or more thresholds (e.g., an RSSI threshold, an RSRP threshold, an RSRQ threshold). For example, the first UE 115 may compare both a first set of measurements performed at the first TRP and a second set of measurements performed at the second TRP with a single measurement threshold, and if at least one set of measurements meets (e.g., is less than) the measurement threshold, the SLSS may be relayed (e.g., if RSRP < Thresh RSRP , then relay). Specifically, the first UE 115 may relay the SLSS via two TRPs or only via the TRP associated with the measurement that meets the measurement threshold.

[0077] In an additional or alternative case, the first UE 115 may compare the sets of measurements performed at each TRP with multiple thresholds. For example, if the measurement results from one or both of these TRPs are below a first measurement threshold (e.g., a lower measurement threshold), the first UE 115 may start a timer. In this example, if the measurement value rises above a second measurement threshold (e.g., an upper measurement threshold) before the timer expires, the first UE 115 may deactivate the timer and avoid relaying the SLSS. Conversely, if the timer expires before the second measurement threshold is met, the first UE 115 may determine to relay the SLSS to other UEs 115 within the wireless communication system 100. The multiple thresholds and the corresponding timers may be applied combinatorially to the two TRPs, applied individually to each TRP, or both.

[0078] In some aspects, the measurements performed at each TPR of the multi-TRP UE 115 may be used to determine the beam direction of the received SLSS such that the relayed SLSS may be transmitted along the same (or similar) beam direction. Such a technique may increase the probability that the relayed SLSS will effectively reach other UEs 115 within the wireless communication system 100.

[0079] The techniques described herein enable a multi-TRP UE 115 to effectively determine whether the multi-TRP UE 115 should relay SLSS to other UEs 115 within the wireless communication system 100. In particular, by comparing the measurements performed at multiple TRPs with one or more measurement thresholds, the multi-TRP UE 115 can efficiently determine whether each multi-TRP UE 115 should become a SyncRef UE 115 to improve the distribution of SLSS throughout the system. Thus, by improving the efficiency and reliability of SLSS distribution within the wireless communication system 100, the techniques described herein can improve clock synchronization between UEs 115 within the wireless communication device 100, resulting in improved wireless communication and an improved user experience.

[0080] Figure 2 An example of a wireless communication system 200 in accordance with aspects of the present disclosure is shown that supports techniques for SLSS transmission with a multi-TRP UE. In some examples, the wireless communication system 200 may implement aspects of the wireless communication system 100. The wireless communication device 200 may include a first UE 115-a, a second UE 115-b, and a third UE 115-c, which may be examples of the UEs 115 Figure 1 described above.

[0081] In some aspects, Figure 2 the first UE 115-a shown in may include a multi-TRP UE 115-a. For example, the first UE 115-a may include a first TRP 205-a and a second TRP 205-b. In some aspects, each of the TRPs 205-a and 205-b may be configured to receive and transmit signals. The TRPs 205-a and 205-b may be configured to transmit signals in combination with each other, individually (e.g., independently of each other), or both together. In this regard, the TRP 205 may include, but is not limited to, an antenna, an antenna panel, and the like.

[0082] In some cases, the TRPs 205 of the first UE 115-a may be located in proximity to each other (e.g., close). In other cases, the TRPs 205 of the first UE 115-a may be physically separated from each other by a certain distance. For example, in the context of a vehicle, the first TRP 205-a may be located near the front of the vehicle, while the second TRP 205-b may be located near the rear of the vehicle. In this example, the first TRP 205-a (e.g., the first antenna panel) and the second TRP 205-b (e.g., the second antenna panel) may be separated from each other by several meters. In the case of a larger UE 115 (e.g., a semi-trailer truck), this physical separation may be even greater, where multiple TRPs 205 may be physically separated from each other by 20 meters or more.

[0083] Due to the separate components, physical locations, and physical separation between the first TRP 205-a and the second TRP 205-b, each TRP 205 may vary depending on the channel. For example, the first TRP 205-a may receive a signal from the second UE 115-b via the communication link 210-a, and the second TRP 205-b may receive a signal from the second UE 115-b via the communication link 210-b. In this example, the signal received at the first TRP 205-a may travel a greater distance compared to the signal received at the second TRP 205-b. The varying propagation distances may result in varying parameters (e.g., characteristics) associated with the signals received by each TRP 205. For example, due to the difference in propagation distances, the signal received at the first TRP 205-a may exhibit lower signal quality (e.g., lower RSRP, lower RSRQ, higher SNR, and higher SINR) compared to the signal received at the second TRP 205-b. Additionally, the signal received at the first TRP 205-a may be later in time than the signal received at the second TRP 205-b. Although the second UE 115-b transmitted the respective signals simultaneously with the same transmit power, these differences in signal parameters (e.g., RSRP, RSRQ, SNR, SINR, reception time) may result.

[0084] Physical obstacles, weather conditions, noise, line-of-sight (LoS) and non-line-of-sight (NLoS), and other conditions may further increase the differences between the signals transmitted and / or received by each TRP 205. For example, the third UE 115-c may transmit a signal to the first TRP 205-a via the communication link 210-c and may transmit a signal to the second TRP 205-b via the communication link 210-d. In this example, the first TRP 205-a may effectively receive these signals. However, the signal transmitted to the second TRP 205-b may be deflected, blocked, or otherwise interfered with by an obstacle 215 such as a truck. In this example, due to the obstacle 215, the signal from the third UE 115-c may not be received at the second TRP 205-b. Additionally or alternatively, the signal received at the second TRP 205-b may have lower signal quality compared to the signal received at the first TRP 205-a.

[0085] These differences in the channel quality and / or signal quality sensed by each TRP 205 may cause problems that multi-TRP UE 115-a encounters but other UEs 115 (e.g., single-TRP UE 115) do not. For example, differences in channel / signal quality may cause difficulties in transmitting and / or receiving SLSS. In this regard, techniques for transmitting and receiving SLSS in the context of multi-TRP UE 115 are described. For example, the techniques described herein may enable multi-TRP UE 115-a of wireless communication system 200 to efficiently and effectively determine whether it should relay a received SLSS to other UEs 115 within wireless communication system 100. For example, the techniques described herein may enable multi-TRP UE 115-a to perform measurements of SLSS received at first TRP 205-a and second TRP 205-b and compare the measurement results with one or more measurement thresholds to determine whether multi-TRP UE 115-a should relay the received SLSS to other UEs 115 within wireless communication system 200. Additionally, in the case where multi-TRP UE 115-a determines that it can relay SLSS, the techniques described herein may enable multi-TRP UE 115-a to determine which TRP 205 multi-TRP UE 115-a should use to transmit (e.g., relay) the SLSS. Reference may be made to Figure 3 to further illustrate and describe the attendant advantages of the techniques described herein.

[0086] Figure 3 An example of a wireless communication system 300 is shown that supports techniques for SLSS transmission with a multi-TRP UE, in accordance with aspects of the present disclosure. In some examples, wireless communication system 300 may implement aspects of wireless communication system 100 or 200. Wireless communication device 300 may include a first UE 115-d, a second UE 115-e, and a third UE 115-f, which may be examples of the Figure 1 UE 115 described. Additionally, wireless communication system 300 may include a satellite 120-a, which may be an example of the Figure 1 satellite 120 described.

[0087] In some aspects, first UE 115-a may include multi-TRP UE 115-d. In this regard, first UE 115-d may include a first TRP 305-a and a second TRP 305-b different from first TRP 305-a. TRP 305-a and 305-b may be configured to transmit signals in combination with each other, individually (e.g., independently of each other), or both together. In this regard, TRP 305 may include, but is not limited to, an antenna, an antenna panel, and the like.

[0088] UEs 115 of the wireless communication system 300 may communicate with each other via communication links. For example, a second UE 115-e may communicate with a first UE 115-d via communication links 315-a and 315-b, and may communicate with a third UE 115-f via a communication link 315-c. The communication links 315-a, 315-b, and 315-c may be examples of sidelink communication links (e.g., PC5 links). In this regard, the communication links 315-a, 315-b, and 315-c may include bidirectional links between respective UEs 115-d, 115-e, and 115-f. In some aspects, each of the respective TRPs 305 may communicate with other wireless devices (e.g., satellite 120-a, UE 115) within the wireless communication system 300 via separate communication links 315. For example, a first TRP 305-a of a first UE 115-d may transmit signals and / or receive signals from a second UE 115-e via a communication link 315-a. Similarly, a second TRP 305-b of the first UE 115-d may transmit signals and / or receive signals from the second UE 115-e via a communication link 315-b. In some aspects, the first UE 115-d and the third UE 115-f may additionally communicate with each other via one or more communication links (e.g., sidelink communication links, PC5 links). For example, a first TRP 305-a of the first UE 115-d may communicate with the third UE 115-f via a communication link 315-d, and a second TRP 305-b of the first UE 115-d may communicate with the third UE 115-f via a second communication link 315-e.

[0089] For efficient communication within a wireless communication system, respective wireless devices of the wireless communication system may synchronize internal clocks with each other and with the network. By synchronizing the internal clocks with the network, the wireless devices may ensure the ability to efficiently exchange wireless transmissions with other wireless devices. In some aspects, the network (e.g., satellite, base station) may send timing information to respective UEs via the wireless communication system. However, as previously stated herein, each wireless device within the wireless communication system may not be able to directly receive timing information from the network. For example, as Figure 3 shown, a second UE 115-e may be capable of directly receiving a timing information signal 310 from a satellite 120-a associated with the network. The timing information signal 310 may include absolute or relative time associated with the wireless communication system 300. In contrast, due to the relative positioning of UEs 115-d and 115-f with respect to the satellite, the distance from the satellite, ground obstacles, noise, or other interference, the first UE 115-d and the third UE 115-f may not be able to directly receive the timing information signal 310 from the satellite 120-a.

[0090] In this case, a UE 115 that can receive the timing information signal 310 from the network can be configured to send an SLSS to other UEs 115 within the wireless communication system. For example, a second UE 115-e can receive the timing information signal 310 from a satellite 120-a and can send an SLSS 320-a to a first UE 115-d and a second UE 115-f. In this regard, the second UE 115-e can be regarded as a SyncRef UE 115 because it sends an SLSS 320-a to other UEs 115 within the system. The SLSS 320-a can include timing information associated with the wireless communication system 300. In this regard, the second UE 115-e can synchronize its internal clock based on the received timing information signal, and the first UE 115-d and the third UE 115-f can synchronize their internal clocks based on (e.g., using) the received SLSS 320-a.

[0091] After receiving the first SLSS 320-a, each of the first UE 115-d and the third UE 115-f can determine whether the respective UE 115 should "relay" the received SLSS 320 to other UEs 115 within the system (e.g., whether they should also become SyncRef UEs 115). For example, the third UE 115-f (e.g., a single TRP UE 115-f) can determine whether to relay the SLSS 320 to other UEs 115 based on the strength of the received SLSS 320 (e.g., RSSI, RSRP, RSRQ). For example, if the strength of the received SLSS 320-a (e.g., RSRP) is higher than a given threshold (e.g., RSRP > Thresh RSRP ), then the third UE 115-f can determine that the SLSS 320-b is strong enough to reach other UEs 115 within the system and can thus avoid relaying the SLSS 320. Conversely, if the strength of the received SLSS 320-a is lower than the given threshold (e.g., RSRP < Thresh RSRP ), then the third UE 115-f can determine that the SLSS 320-b may not be strong enough to reach other UEs 115 within the system and can thus determine to relay the SLSS 320-a to other UEs 115.

[0092] However, this process used by a single TRP UE 115 to determine whether to relay the SLSS 320-a may not be compatible in the context of multiple TRP UEs 115. For example, the first SLSS 320-a received at the first TRP 305-a of the first UE 115-d may be higher than the corresponding threshold (e.g., RSRPTRP1 >Thresh RSRP ) and the first SLSS 320-a received at the second TRP 305-b may be below the corresponding threshold (e.g., RSRP TRP2 <Thresh RSRP ). In this case, the first UE 115-d may not be able to determine whether it should relay the first SLSS 320-a by using conventional techniques. Additionally, if the first UE 115-c determines that it will relay the SLSS 320, the differences in signal strength / quality associated with the respective TRPs 305 may make it difficult to determine which TRP 305 should be used to relay the SLSS 320.

[0093] Thus, to address the problems associated with conventional SLSS transmission / reception techniques, the wireless communication system 300 may support techniques for transmitting and receiving SLSS 320 by the multi-TRP UE 115. Specifically, the techniques described herein may enable the multi-TRP UE 115 of the wireless communication system 300 (e.g., the first UE 115-d) to efficiently and effectively determine whether each multi-TRP UE 115 should relay a received SLSS 320 to other UEs 115 within the wireless communication system 300. Additionally, in the case where the multi-TRP UE 115 (e.g., the first UE 115-d) determines that it can relay the SLSS 320, the techniques described herein may enable the multi-TRP UE 115 to determine which TRP 305 the multi-TRP UE 115 should use to transmit (e.g., relay) the SLSS 320.

[0094] For example, the satellite 120-b (and / or the base station 105) may send a control message to the first UE 115-d, the second UE 115-e, the third UE 115-f, or any combination thereof. The control message may include, but is not limited to, an RRC message. In some aspects, the control message may include an indication of a resource set that each UE 115 among the respective UEs 115 may use to receive the timing information signal 310 from the satellite 120-b. Additionally or alternatively, the control message may include an indication of a resource set that can be used to exchange the SLSS 320 among the respective UEs 115. The resource set may include a time resource set, a frequency resource set, a spatial resource set, or any combination thereof.

[0095] In some aspects, the satellite 120-b (and / or the base station 105) may send the timing information signal 310 to the UE 115-d, the UE 115-e, and / or the UE 115-f. In some aspects, the timing information signal 310 may be received by all UEs 115 or only a subset of the UEs 115. For example, as Figure 3As shown in [Figure 0], the timing information signal 310 can be received only by the second UE 115-e. The timing information signal 310 can include absolute or relative time associated with the wireless communication system 300. In this regard, the second UE 115-e can synchronize (e.g., selectively adjust) one or more internal timers or clocks based on the received timing information signal 310. In some aspects, the satellite 120-b can send the timing information signal 310 based on sending a control message to the UE 115. In this regard, the second UE 115-e can receive the timing information signal 310 based on (e.g., according to, using) a resource set for receiving the timing information signal 310 from the satellite 120-b, where the resource set is indicated in the received control message.

[0096] In some aspects, the first UE 115-d can determine a resource set associated with receiving the SLSS 320 (e.g., the first SLSS 320-a) from another UE 115, a resource set associated with sending the SLSS 320 (e.g., the second SLSS 320-b and 320-c) to another UE 115, or both. In some cases, the first UE 115-d can determine the resource set for sending / receiving the SLSS 320 based on a control message received from the satellite 120-b. For example, the control message can indicate the resource set that the first UE 115-d will use for sending and receiving the SLSS 320. In this example, the first UE 115-d can determine a first subset of the resource set that will be used to receive the SLSS 320 (e.g., the first SLSS 320-a) from another UE 115 (e.g., the second UE 115-e), and a second subset of the resource set that will be used to send the SLSS 320 (e.g., the second SLSS 320-b and 320-c) to another UE 115-f (e.g., the third UE 115-f).

[0097] After receiving the timing information signal 310, the second UE 115-d may send a first SLSS 320-a to the first UE 115-d, the second UE 115-f, or both. For example, the second UE 115-e may send the first SLSS 320-a to the first TRP 305-a via the communication link 315-a, send the first SLSS 320-a to the second TRP 305-b via the communication link 315-b, and send the first SLSS 320-a to the third UE 115-f via the communication link 315-c. The second UE 115-e may use unicast technology, multicast (e.g., multi-cast) technology, broadcast technology, or any combination thereof to send the first SLSS 320-a. The second UE 115-e may send the first SLSS 320-e based on receiving a control message from the satellite 120-b, receiving the timing information signal 310, or both. In some cases, the first SLSS 320-a may be received by both the first UE 115-d and the third UE 115-f, or only by a subset of the UE115-d and UE 115-f. For example, the third UE 115-f may be out of range, blocked, or otherwise prevented from receiving the first SLSS 320-a, such that the first SLSS 320-a is received only by the first UE 115-d (e.g., the first TRP 305-a and the second TRP 305-b). In some cases, the first UE 115-d may synchronize (e.g., selectively adjust) one or more internal timers or clocks based on the first SLSS 320-a.

[0098] In some aspects, the first UE 115-d may receive the first SLSS 320-a at the first TRP 305-a and the second TRP 305-b. Additionally or alternatively, the first UE 115-d may receive the first SLSS320-a based on the determined SLSS resources. For example, in the case where the first UE 115-d determines a first subset of the resource set to be used for receiving the first SLSS 320-a and a second subset of the resource set to be used for sending the second SLSS 320-b and 320-d, the first UE 115-d may receive the first SLSS 320-a based on (e.g., using) the first subset of the resource set.

[0099] In some aspects, the first UE 115-d may perform a first set of measurements on the first SLSS 320-a received at the first TRP 305-a and a second set of measurements on the second SLSS 320-b received at the second TRP 305-b. These measurements may include RSSI measurements, RSRP measurements, RSRQ measurements, SNR measurements, SINR measurements, or any combination thereof. The first UE 115-d may perform the set of measurements based on receiving a control message from the satellite 120-b, determining resources for receiving / transmitting the SLSS 320, receiving the first SLSS 320-a, or any combination thereof.

[0100] In some aspects, the first UE 115-d may estimate the beam direction of the first SLSS 320-a. The beam direction may include the direction in which the first SLSS 320-a is received by the first TRP 305-a, the second TRP 305-b, or both. In some aspects, the first UE 115-d may estimate the beam direction of the first SLSS 320-a based on the first set of measurements, the second set of measurements, or both. For example, in the case where the RSRP measurement result within the first set of measurements associated with the first TRP 305-a determined by the first UE 115-d is greater than the RSRP measurement result in the second set of measurements associated with the second TRP 305-b, the first UE 115-d may determine that the second UE 115-e is closer to the first TRP 305-a and may estimate the beam direction based on the first and second RSRP measurement results.

[0101] After performing the set of measurements, the first UE 115-d may compare the first set of measurements, the second set of measurements, or both with one or more measurement thresholds. The one or more measurement thresholds may include, but are not limited to, an RSSI threshold, an RSRP threshold, an RSRQ threshold, an SNR threshold, a SINR threshold, or any combination thereof. The first UE 115-d may determine whether the first set of measurements and / or the second set of measurements meet the one or more measurement thresholds.

[0102] In some cases, if a set of measurements indicates poor link / signal quality relative to a measurement threshold, the set of measurements may be said to "meet" the corresponding measurement threshold. For example, in the case of RSRP, RSRQ, or RSRQ measurements, if the measurement result is less than or equal to the corresponding measurement threshold (e.g., Thresh RSSI , Thresh RSRP , Thresh RSRQ ), then it may be determined that the corresponding measurement result meets the corresponding measurement threshold (e.g., if RSSI ≤ Thresh RSSI , RSRP ≤ Thresh RSRP , RSRQ ≤ ThreshRSRQ , then the threshold is met). In contrast, if the measurement result is greater than the corresponding measurement threshold, it can be determined that the corresponding measurement result does not meet the corresponding measurement threshold (e.g., if RSSI > Thresh RSSI , RSRP > Thresh RSRP , RSRQ > Thresh RSRQ , then the threshold is not met).

[0103] In some cases, the first UE 115-d may compare the first set of measurements and the second set of measurements with a single measurement threshold. For example, the first set of measurements may include a first RSRP measurement (RSRP TRP1 ), and the second set of measurements may include a second RSRP measurement (RSRP TRP2 ). In this example, the first UE 115-d may compare the first RSRP measurement and the second RSRP measurement with a single RSRP threshold. When the first UE 115-d determines that both the first RSRP measurement and the second RSRP measurement do not meet the RSRP threshold (RSRP TRP1 > Thresh RSRP , and RSRP TRP2 > Thresh RSRP ), the first UE 115-d may avoid sending (e.g., relaying) the second SLSSs 320-b and 320-c.

[0104] In some aspects, the first UE 115-d may avoid sending the second SLSSs 320-b and 320-c based on the failure of these sets of measurements to meet the corresponding measurement thresholds. In this aspect, the first UE 115-d may determine that the first SLSS 320-a exhibits sufficient power or quality to reach other UEs 115 (e.g., the third UE 115-f) within the wireless communication system 300 based on these sets of measurements meeting the corresponding measurement thresholds. Therefore, since the first SLSS 320-a can effectively reach other UEs 115 within the system, the first UE 115-d may avoid sending (e.g., relaying) the second SLSSs 320-b and 320-c.

[0105] Conversely, the first UE 115-d may determine that the first RSRP measurement and / or the second RSRP measurement meets the RSRP threshold (e.g., RSRP TRP1 ≤ Thresh RSRP and / or RSRP TRP2 ≤ Thresh RSRP)。When one or both of the measurements in these groups (e.g., the first RSRP measurement, the second RSRP measurement) meet the corresponding measurement thresholds, the first UE 115-d may send (e.g., relay) the second SLSS 320-b and / or 320-c to the third UE 115-f. The first UE 115-d may use unicast technology, multicast (e.g., multi-cast) technology, broadcast technology, or any combination thereof, to send the second SLSS 320-b, 320-c.

[0106] In some aspects, the first UE 115-d may send the second SLSS 320-b and / or 320-c based on the first set of measurements, the second set of measurements, or both meeting one or more measurement thresholds. Thus, the first UE 115-d may send the second SLSS 320-b, 320-c based on receiving a control message from the satellite 120-b, determining resources for sending / receiving the SLSS 320, receiving the first SLSS 320-a, performing multiple sets of measurements at the TRPs 305-a and 305-b, estimating the beam direction of the first SLSS 320-a, comparing these sets of measurements with the one or more measurement thresholds, or any combination thereof.

[0107] For example, when both the first set of measurements and the second set of measurements meet one or more measurement thresholds (e.g., RSSI TRP1,TRP2 ≤Thresh RSSI , RSRP TRP1,TRP2 ≤Thresh RSRP , RSRQ TRP1,TRP2 ≤Thresh RSRQ ), the first UE 115-d may determine to send the second SLSS 320-b, 320-c. In this example, the first UE 115-d may use the first TRP 305-a to send the second SLSS 320-b, may use the second TRP 305-b to send the second SLSS 320-c, or both, based on the two sets of measurements associated with each TRP 305 meeting the corresponding measurement thresholds.

[0108] Additionally or alternatively, the first UE 115-d may send the second SLSS using only one of the TRPs 305 based on these sets of measurements, the estimated beam direction, etc. For example, if only one of the first set of measurements or the second set of measurements meets the one or more thresholds, the first UE 115-d may determine to send the second SLSS 320-b, 320-c. For example, the first UE 115-d may determine that the second set of measurements meets the one or more measurement thresholds (e.g., RSSI TRP2 ≤Thresh RSSI , RSRP TRP2≤ Thresh RSRP , RSRQ TRP2 ≤ Thresh RSRQ ), but it can be determined that the first set of measurements fails to meet the one or more measurement thresholds (e.g., RSSI TRP1 > Thresh RSSI , RSRP TRP1 > Thresh RSRP , RSRQ TRP1 > Thresh RSRQ ). In this example, the first UE 115-d can determine to send the second SLSS 320-b, 320-c based on the second set of measurements meeting the one or more measurement thresholds.

[0109] Continuing with the same example, the first UE 115-d can use the second TRP 305-b and / or the first TRP 305-a to send the second SLSS 320-b, 320-c. For example, the first UE 115-d can use the second TRP 305-b to send the second SLSS 305-c based on determining that the second set of measurements meets the one or more measurement thresholds, determining that the first set of measurements fails to meet the one or more measurement thresholds, or both. In some cases, the first UE 115-d can use the second TRP 305-b to send the second SLSS 320-a and can avoid using the first TRP 305-a to send the second SLSS 320-b based on determining that the first set of measurements fails to meet the one or more measurement thresholds. In some cases, the first TRP 305-b can avoid sending the second SLSS 320-b by sending a null value using the same resource set (e.g., the same subcarriers) as used by the second TRP 305-b for sending the second SLSS 320-c. Additionally or alternatively, in other cases, the first UE 115-d can use both the first TRP 305-a and the second TRP 305-b to send the second SLSS 320-b, 320-c based on the second set of measurements meeting the measurement thresholds and regardless of the first set of measurements failing to meet the measurement thresholds.

[0110] In some aspects, the first UE 115-d can send (e.g., relay) the second SLSS 320-b, 320-c from the first TRP 305-a and / or the second TRP 305-b based on (e.g., according to) the estimated beam direction of the first SLSS 320-a. For example, in the case where the first UE 115-d estimates the beam direction of the first SLSS 320-a, the first UE 115-d can send the second SLSS 320-b, 320-c along a beam direction equal (or substantially equal) to the estimated beam direction.

[0111] Additionally or alternatively, the first UE 115-d may send the second SLSSs 320-b, 320-c (or null values) based on the SLSS resources determined for transmitting / receiving the SLSS 320. For example, in a case where the first UE 115-d determines a first subset of the resource set to be used for receiving the first SLSS 320-a and a second subset of the resource set to be used for transmitting the second SLSSs 320-b, 320-c, the first UE 115-d may transmit (e.g., relay) the second SLSSs 320-b, 320-c based on (e.g., using) the second subset of the resource set. For example, the first UE 115-d may use a first set of time slots of the resource set to receive the first SLSS 320-a (e.g., receive the first SLSS 320-a on time slots 4 and 8), and may use a second set of time slots of the resource set to transmit the second SLSSs 320-b, 320-c (e.g., transmit the second SLSSs 320-b, 320-c on time slots 2 and 6).

[0112] In an additional or alternative case, the first UE 115-d may compare a first set and a second set of measurements associated with the first TRP 305-a and the second TRP 305-b with multiple measurement thresholds (e.g., first / second measurement thresholds, upper / lower measurement thresholds). For example, the first UE 115-d may compare the first and second sets of measurements with a first measurement threshold (e.g., a lower measurement threshold). For example, the first UE 115-d may determine that a first RSRP measurement of the first set of measurements, a second RSRP measurement associated with the second set of measurements, or both satisfy the first (lower) measurement threshold (e.g., RSRP TRP1 ≤LowerThresh RSRP and / or RSRP TRP2 ≤LowerThresh RSRP ).

[0113] In a case where the first set of measurements, the second set of measurements, or both satisfy the first measurement threshold, the first UE 115-d may start one or more timers based on the first set of measurements, the second set of measurements, or both satisfying the first measurement value threshold (e.g., LowerThresh RSRP ). In some aspects, the first UE 115-d may use a single timer for both the first TRP 305-a and the second TRP 305-b (e.g., a timer associated with both the first TRP 305-a and the second TRP 305-b). For example, in a case where the first set of resources, the second set of resources, or both satisfy the first measurement threshold, the first UE 115-d may start a single timer associated with both the first and second TRPs 305.

[0114] In another or alternative aspect, the first UE 115-d may be configured to operate a separate timer for each TRP 305. In this aspect, the UE 115-d may operate a first timer associated with the first TRP 305-a and a second timer associated with the second TRP 305-b. In this case, the timers may operate independently of each other (e.g., start, deactivate). For example, in a case where a first set of measurements meets a first measurement threshold but a second set of measurements fails to meet the first measurement threshold (e.g., ≤ LowerThresh RSRP ), the first UE 115-d may start the second timer associated with the second TRP 305-b based on the second set of measurements failing to meet the first measurement threshold. In this example, the first UE 115-d may start or not start the first timer associated with the first TRP 305-b based on starting the second timer. In this aspect, the first UE 115-d may initiate a separate timer associated with each TRP 305 based on a corresponding set of measurements associated with the respective TRP 305 meeting the first measurement threshold.

[0115] In some aspects, the one or more timers may be associated with a predetermined or pre-configured duration (e.g., a pre-configured expiration time). The expiration time associated with each timer may be the same or different. Additionally, the expiration time associated with the one or more timers may be signaled to the first UE 115-d via control / configuration signaling, pre-configured by the first UE 115-d, or both. In some cases, the first UE 115-d may selectively adjust the expiration time associated with the one or more timers based on the determined channel conditions, the distance between the first UE 115-d and other UEs 115 within the system, or any combination thereof.

[0116] In some aspects, the first UE 115-d may deactivate the one or more timers based on the first set of measurements, the second set of measurements, or both meeting a second measurement threshold different from the first measurement threshold (e.g., LowerThresh RSRP ). In some aspects, if the measurements of each group indicate that the quality / intensity of the first SLSS 320-a is greater than or equal to the second measurement threshold, it may be determined that the corresponding set of measurements "meets" the second measurement threshold (e.g., if RSSI RSRP ≥ UpperThresh TRP1,TRP2 , RSRP RSSI ≥ UpperThresh TRP1,TRP2 , RSRQ RSRP , RSRQ TRP1,TRP2≥UpperThresh RSRQ , the second measurement threshold is satisfied). In this regard, if the strength / quality associated with the first SLSS 320-a drops below a predetermined level / threshold, the first UE 115-d may activate one or more timers, and if the strength / quality associated with the first SLSS 320-a rises above a second predetermined level / threshold, one or more timers may be deactivated.

[0117] For example, in the case where the first UE 115-d starts a single timer based on the first set of measurements and / or the second set of measurements satisfying the first measurement threshold, if it is subsequently determined that the first set of measurements, the second set of measurements, or both satisfy the second measurement threshold, the first UE 115-d may deactivate the single timer. As another example, in the case where the first UE 115-d operates (e.g., starts, deactivates) a separate timer associated with a corresponding TRP 305, if it is subsequently found that the measurements associated with the corresponding TRP 305 satisfy the second measurement threshold, the first UE 115-d may deactivate the timer associated with the corresponding TRP 305. For example, if the second set of measurements associated with the second TRP 305-b satisfy the first measurement threshold, the first UE 115-d may start a second timer associated with the second TRP 305-b (e.g., if RSRP TRP2 ≤LowerThresh RSRP , the second timer is started). Subsequently, if it is found that the second set of measurements associated with the second TRP 305-b satisfy the second measurement threshold, the first UE 115-d may deactivate the second timer (e.g., if RSRP TRP2 ≥UpperThresh RSRP , the second timer is deactivated).

[0118] In some aspects, the first UE 115-d may determine whether to deactivate the timer at regular or irregular intervals throughout the entire expiration time of the timer. In the case where the first UE 115-d determines to deactivate the one or more timers (e.g., the second measurement threshold is satisfied before the timer expires), the first UE 115-d may avoid transmitting the second SLSS 320-b, 320-c based on the deactivation of the one or more timers, as discussed previously herein.

[0119] Conversely, if the first UE 115-d determines that a timer has expired before the second measurement threshold is met, the first UE 115-d may send (e.g., relay) the second SLSSs 320-b, 320-c. In some aspects, the first UE 115-d may determine the expiration of the timer based on the duration of each of the respective timers, the time at which each timer was started, or both. For example, if the first UE 115-d determines that the second measurement threshold is not met within the expiration time of the timer, the UE 115-d may determine the expiration of the timer. As previously described herein, the first UE 115-d may determine the expiration of a single timer associated with two TRPs 305, may independently determine the expiration of separate timers associated with the respective TRPs 305, or both.

[0120] After determining that the timer has expired, the first UE 115-d may send the second SLSSs 320-b, 320-c based on the expiration of the one or more timers. In some aspects, the first UE 115-d may use only the TRP 305 associated with the expired timer, use both TRPs 305, or both, to send the second SLSS 320. For example, if the first UE 115-d determines that the second timer associated with the second TRP 305-b has expired, the first UE 115-d may use only the second TRP 305-b to send the second SLSS 320-c. For example, if the first UE 115-d determines that the second timer associated with the second TRP 305-b has expired, the first UE 115-d may use the second TRP 305-b to send the second SLSS 320-c and may use the first TRP 305-a to send the second SLSS 320-bc.

[0121] The techniques described herein may enable the first UE 115-d (e.g., the multi-TRP UE 115-d) to effectively determine whether the first UE 115-d should relay the SLSS 320 to other UEs 115 within the wireless communication system 300. In particular, by comparing the measurements performed at multiple TRPs 305 with one or more measurement thresholds, the first UE 115-d can efficiently determine whether the first UE 115-b should become a SyncRef UE 115 to improve the distribution of the SLSS 320 throughout the wireless communication system 300. Thus, by improving the efficiency and reliability of the SLSS 320 distribution, the techniques described herein may improve the clock synchronization between UEs 115 within the wireless communication system 300, thereby obtaining improved wireless communication and an improved user experience.

[0122] Figure 4In aspects of the present disclosure, an example of a process flow 400 that supports techniques for SLSS transmission with a multi-TRP UE is shown. In some examples, the process flow 400 may implement aspects of, or be implemented by, a wireless communication system 100, 200, 300, or any combination thereof. For example, the process flow 400 may show that a first UE 115-g receives a first SLSS from a second UE 115-h, determines whether parameters associated with the first SLSS meet one or more parameter thresholds, and sends a second SLSS to a third UE 115-i, as described with reference to Figures 1 to 3 as described.

[0123] In some cases, the process flow 400 may include a first UE 115-g, a second UE 115-h, a third UE 115-i, and a base station 105-b, which may be examples of the corresponding devices as described herein. Figure 4 The first UE 115-g, the second UE 115-h, and the third UE 115-i shown in Figure 3 may be examples of the first UE 115-d, the second UE 115-e, and the third UE 115-f shown in Figure 4 In this regard, the first UE 115-g may include a multi-TRP UE 115, and the second UE 115-h may include a SyncRef UE 115. In some aspects, Figure 3 the respective UEs 115 shown in

[0124] may communicate with each other via sidelink communication links (e.g., the communication links 315-a, 315-b, and 315-c shown in

[0125] At 405, base station 105-b may send a control message to the first UE 115-g, the second UE 115-h, the third UE 115-i, or any combination thereof. The control message may include, but is not limited to, an RRC message. In some aspects, the control message may include an indication of a resource set that each of the respective UEs 115 can use to receive a timing information signal from base station 105-b. Additionally or alternatively, the control message may include an indication of a resource set that can be used to exchange SLSSs among the respective UEs 115. The resource set may include a time resource set, a frequency resource set, a spatial resource set, or any combination thereof.

[0126] At 410, base station 105-b may send a timing information signal. In some aspects, the timing information signal may be received by all UEs 115, or only by a subset of UEs 115. For example, as Figure 4 shown, the timing information signal may be received only by the second UE 115-h. The timing information signal may include absolute or relative time associated with the wireless communication system. In this aspect, the second UE 115-h may synchronize (e.g., selectively adjust) one or more internal timers or clocks based on the received timing information signal. In some aspects, base station 105-d may send the timing information signal at 410 based on sending the control message at 405. In this aspect, the second UE 115-h may receive the timing information signal based on (e.g., according to, using) the resource set for receiving the timing information signal from base station 105-b, where the resource set is indicated in the control message.

[0127] At 415, the first UE 115-g may determine a resource set associated with receiving an SLSS signal from another UE 115, a resource set associated with sending an SLSS signal to another UE 115, or both. In some cases, the first UE 115-g may determine the resource set at 415 based on the control message received at 405. For example, the control message may indicate the resource set that the UEs 115 will use to exchange SLSSs. In this example, the first UE 115-g may determine a first subset of the resource set to be used for receiving an SLSS from another UE 115 and a second subset of the resource set to be used for sending an SLSS to another UE 115.

[0128] At 420, the second UE 115-h may send a first SLSS to the first UE 115-g, the second UE 115-i, or both. The second UE 115-h may use unicast techniques, multicast (e.g., multi-cast) techniques, broadcast techniques, or any combination thereof to send the first SLSS. The second UE 115-h may send the first SLSS based on receiving a control message at 405, receiving a timing information signal at 410, or both. In some cases, the first SLSS may be received by both the UE 115-g and the UE 115i, or only by a subset of the UE 115-g and the UE 115-i. For example, as Figure 4 shown, the third UE 115-c may be out of range, blocked, or otherwise prevented from receiving the first SLSS such that the first SLSS is received only by the first UE 115-g. In some cases, the first UE 115-g may synchronize (e.g., selectively adjust) one or more internal timers or clocks based on the first SLSS.

[0129] In some aspects, the first UE 115-g may receive the first SLSS at a first TRP and a second TRP different from the first TRP. Additionally or alternatively, the first UE 115-g may receive the first SLSS based on the SLSS resources determined at 415. For example, in the case where the first UE 115-g determines a first subset of a resource set to be used for receiving SLSS from another UE 115 and a second subset of the resource set to be used for sending SLSS to another UE 115, the first UE 115-g may receive the first SLSS at 420 based on (e.g., using) the first subset in the resource set.

[0130] At 425, the first UE 115-g may perform a first set of measurements on the first SLSS received at the first TRP of the first UE 115. The first set of measurements may include RSSI measurements, RSRP measurements, RSRQ measurements, SNR measurements, SINR measurements, or any combination thereof. The first UE 115-g may perform the first set of measurements based on receiving a control message at 405, determining SLSS resources at 415, receiving the first SLSS at 420, or any combination thereof.

[0131] At 430, the first UE 115-g may perform a second set of measurements on a first SLSS received at a second TRP of the first UE 115-g. The second set of measurements may include RSSI measurements, RSRP measurements, RSRQ measurements, SNR measurements, SINR measurements, or any combination thereof. The first UE 115-g may perform the second set of measurements based on receiving a control message at 405, determining SLSS resources at 415, receiving the first SLSS at 420, performing the first set of measurements at 425, or any combination thereof.

[0132] At 435, the first UE 115-g may estimate the beam direction of the first SLSS. In some aspects, the first UE 115-g may estimate the beam direction of the first SLSS based on the first set of measurements, the second set of measurements, or both. For example, in a case where the RSRP measurement in the first set of measurements associated with the first TRP determined by the first UE 115-g is greater than the RSRP measurement within the second set of measurements associated with the second TRP, the first UE 115-g may determine that the second UE 115-h is closer to the first TRP and may estimate the beam direction based on the first and second RSRP measurements.

[0133] At 440, the first UE 115-g may compare the first set of measurements, the second set of measurements, or both with one or more measurement thresholds. The one or more measurement thresholds may include, but are not limited to, an RSSI threshold, an RSRP threshold, an RSRQ threshold, an SNR threshold, a SINR threshold, or any combination thereof. The first UE 115-g may determine whether the first set of measurements and / or the second set of measurements meet the one or more measurement thresholds.

[0134] In some cases, if a set of measurements indicates poor link / signal quality relative to a measurement threshold, then it can be said that the set of measurements "meets" the corresponding measurement threshold. For example, in the case of RSRP, RSRQ, or RSRQ measurements, if the measurement result is less than or equal to the corresponding measurement threshold (e.g., Thresh RSSI , Thresh RSRP , Thresh RSRQ ), then it can be determined that the corresponding measurement value meets the corresponding measurement threshold (e.g., if RSSI ≤ Thresh RSSI , RSRP ≤ Thresh RSRP , RSRQ ≤ Thresh RSRQ , then the threshold is met). In contrast, if the measurement result is greater than the corresponding measurement threshold, then it can be determined that the corresponding measurement value does not meet the corresponding measurement threshold (e.g., if RSSI > Thresh RSSI , RSRP > Thresh RSRP , RSRQ > ThreshRSRQ , then the threshold is not met).

[0135] In some cases, the first UE 115-g may compare the first set of measurements and the second set of measurements with a single measurement threshold. For example, the first set of measurements may include a first RSRP measurement value (RSRP TRP1 ), and the second set of measurements may include a second RSRP measurement value (RSRP TRP2 ). In this example, the first UE 115-g may compare the first RSRP measurement and the second RSRP measurement with a single RSRP threshold. When the first UE 115-g determines that neither the first RSRP measurement value nor the second RSRP measurement value meets the RSRP threshold (RSRP TRP1 >Thresh RSRP , and RSRP TRP2 >Thresh RSRP ), the process flow 400 may go to 465.

[0136] At 465, the first UE 115-g may avoid sending (e.g., relaying) the second SLSS. The first UE 115-g may avoid sending the second SLSS based on the failure of these sets of measurements to meet the corresponding measurement thresholds at 440. In this regard, the first UE 115-g may determine that the first SLSS exhibits sufficient power or quality to reach other UEs 115 (e.g., the third UE 115-i) within the system based on these sets of measurements meeting the corresponding measurement thresholds. Thus, since the first SLSS can effectively reach other UEs 115 within the system, the first UE 115-g may avoid sending (e.g., relaying) the second SLSS.

[0137] Referring back to 440 of the process flow 400 again. In other cases, the first UE 115-g may determine that the first RSRP measurement and / or the second RSRP measurement meets the RSRP threshold (e.g., RSRP TRP1 ≤Thresh RSRP and / or RSRP TRP2 ≤Thresh RSRP ). When one or both of these sets of measurements (e.g., the first RSRP measurement, the second RSRP measurement) meet the corresponding measurement thresholds, the process flow 400 may go to 460.

[0138] At 460, the first UE 115-g may send (e.g., relay) the second SLSS to the third UE 115-i. The first UE 115-b may use unicast technology, multicast (e.g., multi-cast) technology, broadcast technology, or any combination thereof, to send the second SLSS. In some aspects, the first UE 115-g may send the second SLSS at 460 based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds at 440. Thus, the first UE 115-g may send the second SLSS at 460 based on receiving a control message at 405, determining SLSS resources at 415, receiving the first SLSS at 420, performing multiple sets of measurements at 425 and 430, estimating a beam direction at 435, comparing the multiple sets of measurement results with one or more measurement thresholds at 440, or any combination thereof.

[0139] For example, in a case where both the first set of measurements and the second set of measurements satisfy one or more measurement thresholds (e.g., RSSI TRP1,TRP2 ≤Thresh RSSI , RSRP TRP1,TRP2 ≤Thresh RSRP , RSRQ TRP1,TRP2 ≤Thresh RSRQ ), the first UE 115-g may determine to send the second SLSS at 460. In this example, the first UE 115-g may use the first TRP, the second TRP, or both to send the second SLSS based on the two sets of measurements associated with each TRP satisfying the corresponding measurement thresholds. Additionally or alternatively, the first UE 115-g may send the second SLSS using only one of the TRPs based on these sets of measurements, the estimated beam direction, etc.

[0140] By way of another example, if only one of the first set of measurements or the second set of measurements satisfies the one or more thresholds, the first UE 115-g may determine to send the second SLSS at 460. For example, at 440, the first UE 115-g may determine that the second set of measurements satisfies the one or more measurement thresholds (e.g., RSSI TRP2 ≤Thresh RSSI , RSRP TRP2 ≤Thresh RSRP , RSRQ TRP2 ≤Thresh RSRQ ), but may determine that the first set of measurements fails to satisfy the one or more measurement thresholds (e.g., RSSI TRP1 >Thresh RSSI , RSRP TRP1 >Thresh RSRP , RSRQTRP1 >Thresh RSRQ )。In this example, the first UE 115-g may determine to transmit the second SLSS at 460 based on the second set of measurements satisfying the one or more measurement thresholds.

[0141] Continuing with the same example, the first UE 115-g may use the second TRP and / or the first TRP to transmit the second SLSS. For example, the first UE 115-g may use the second TRP to transmit the second SLSS based on determining that the second set of measurements satisfies the one or more measurement thresholds, determining that the first set of measurements fails to satisfy the one or more measurement thresholds, or both. In some cases, the first UE 115-g may use the second TRP to transmit the second SLSS and may avoid using the first TRP to transmit the second SLSS based on determining that the first set of measurements fails to satisfy the one or more measurement thresholds. In some cases, the first TRP may avoid transmitting the second SLSS by transmitting a null value using the same resource set (e.g., the same subcarriers) as the second TRP uses to transmit the second SLSS. Additionally or alternatively, in other cases, the first UE 115-g may use both the first TRP and the second TRP to transmit the second SLSS based on the second set of measurements satisfying the measurement threshold and regardless of the first set of measurements failing to satisfy the measurement threshold.

[0142] In some aspects, the first UE 115-g may transmit (e.g., relay) the second SLSS at 460 from the first TRP and / or the second TRP based on (e.g., according to) the beam direction estimated at 435. For example, in the case where the first UE 115-g estimates the beam direction of the first SLSS received at 420, the first UE 115-g may transmit the second SLSS along a beam direction equal (or substantially equal) to the estimated beam direction.

[0143] Additionally or alternatively, the first UE 115-g may transmit the second SLSS (or a null) based on the SLSS resources determined at 415. For example, in the case where the first UE 115-g determines a first subset of the resource set that will be used to receive the SLSS from another UE 115 and a second subset of the resource set that will be used to transmit the SLSS to another UE 115, the first UE 115-g may transmit (e.g., relay) the second SLSS at 460 based on (e.g., using) the second subset of the resource set. For example, the first UE 115-g may use the first set of time slots of the resource set to receive the first SLSS (e.g., receive the first SLSS on time slots 4 and 8) and may use the second set of time slots of the resource set to transmit the second SLSS (e.g., transmit the second SLSS on time slots 2 and 6).

[0144] Reference will again be made to 440 in process flow 400. In additional or alternative cases, the first UE 115-g may compare the first and second sets of measurements associated with the first TRP and the second TRP with multiple measurement thresholds (e.g., first / second measurement thresholds, upper / lower measurement thresholds). For example, at 440, the first UE 115-g may compare the first and second sets of measurements with a first measurement threshold (e.g., a lower measurement threshold). For example, the first UE 115-g may determine that a first RSRP measurement value of the first set of measurements, a second RSRP measurement value associated with the second set of measurements, or both satisfy the first (lower) measurement threshold (e.g., RSRP TRP1 ≤LowerThresh RSRP and / or RSRP TRP2 ≤LowerThresh RSRP ). In the case where the first set of measurements, the second set of measurements, or both at 440 satisfy the first measurement threshold, the process flow may proceed to 445.

[0145] At 445, the first UE 115-g may start one or more timers based on the first set of measurements, the second set of measurements, or both satisfying the first measurement value threshold (e.g., LowerThresh RSRP ). In some aspects, the first UE 115-g may use a single timer for both the first TRP and the second TRP (e.g., a timer associated with both the first TRP and the second TRP). For example, in the case where the first set of resources, the second set of resources, or both satisfy the first measurement threshold, the first UE 115-g may start a single timer associated with both the first and second TRPs.

[0146] In additional or alternative aspects, the first UE 115-g may be configured to operate separate timers for each TRP. In this aspect, the UE 115-g may operate a first timer associated with the first TRP and a second timer associated with the second TRP. In this case, the timers may operate independently of each other (e.g., start, deactivate). For example, in the case where the first set of measurements satisfies the first measurement threshold but the second set of measurements fails to satisfy the first measurement threshold, the first UE 115-g may start the second timer associated with the second TRP based on the second set of measurements failing to satisfy the first measurement threshold. In this example, the first UE 115-g may start or not start the first timer associated with the first TRP based on starting the second timer. In this aspect, the first UE 115-g may initiate a separate timer associated with each TRP based on the corresponding set of measurement values associated with the respective TRP satisfying the first measurement threshold.

[0147] At 450, the first UE 115-g may determine whether one or more timers activated at 445 have been deactivated. In some aspects, the first UE 115-g may deactivate the one or more timers based on the first set of measurements, the second set of measurements, or both satisfying a second measurement threshold different from the first measurement threshold (e.g., UpperThresh RSRP ). In some aspects, if the measurements of these sets indicate that the quality / intensity of the first SLSS is greater than or equal to the second measurement threshold, it may be determined that the measurements of the corresponding set "satisfy" the second measurement threshold (e.g., if RSSI TRP1,TRP2 ≥UpperThresh RSSI , RSRP TRP1,TRP2 ≥UpperThresh RSRP , RSRQ TRP1,TRP2 ≥UpperThresh RSRQ , then the second measurement threshold is satisfied). In this aspect, if the intensity / quality associated with the first SLSS drops below a predetermined level / threshold, the first UE 115-g may activate one or more timers, and if the intensity / quality associated with the first SLSS rises above a second predetermined level / threshold, one or more timers may be deactivated.

[0148] For example, in the case where the first UE 115-g starts a single timer based on the first set and / or the second set of measurements satisfying the first measurement threshold, if it is subsequently determined that the first set of measurements, the second set of measurements, or both satisfy the second measurement threshold, the first UE 115-g may deactivate the single timer. As another example, in the case where the first UE 115-g operates (e.g., starts, deactivates) a separate timer associated with a corresponding TRP, if it is subsequently found that the measurements associated with the corresponding TRP satisfy the second measurement threshold, the first UE 115-g may deactivate the timer associated with the corresponding TRP. For example, if the second set of measurements associated with the second TRP satisfies the first measurement threshold, the first UE 115-g may start a second timer associated with the second TRP (e.g., if RSRP TRP2 ≤LowerThresh RSRP , then start the second timer). Subsequently, if it is found that the second set of measurements associated with the second TRP satisfies the second measurement threshold, the first UE 115-g may deactivate the second timer (e.g., if RSRP TRP2 ≥UpperThresh RSRP , then deactivate the second timer).

[0149] In some aspects, the first UE 115-g may determine whether to activate a timer at regular or irregular intervals throughout the entire expiration time of the timer. In the case where the first UE 115-g determines to deactivate the one or more timers (e.g., a second measurement threshold is met before the timer expires), the process flow 400 may proceed to 465. At 465, the first UE 115-g may avoid transmitting a second SLSS based on the deactivation of the one or more timers, as discussed previously herein. Conversely, if the first UE 115-g determines that the timer has not expired, the process flow 400 may proceed to 455.

[0150] At 455, the first UE 115-g may determine that the one or more timers have expired. In some aspects, the first UE 115-g may determine the expiration of a timer based on the duration of each timer in the respective timers, the time at which each timer was started, or both. For example, if the first UE 115-g determines that a second measurement threshold is not met within the expiration time of the timer, the UE 115-g may determine the expiration of the timer. As previously described herein, the first UE 115-g may determine the expiration of a single timer associated with two TRPs, may independently determine the expiration of separate timers associated with the respective TRPs, or both.

[0151] After determining that the timer has expired, the process flow 400 may proceed to 460. At 460, the first UE 115-g may transmit a second SLSS based on the expiration of the one or more timers. In some aspects, the first UE 115-g may transmit the second SLSS using only the TRP associated with the expired timer, using both TRPs, or both. For example, if the first UE 115-g determines that a second timer associated with a second TRP has expired, at 460, the first UE 115-g may transmit the second SLSS using only the second TRP. For example, if the first UE 115-g determines that a second timer associated with a second TRP has expired, at 460, the first UE 115-g may transmit the second SLSS using both the second TRP and the first TRP.

[0152] The techniques described herein may enable a first UE 115-g (e.g., a multi-TRP UE 115-g) to effectively determine whether the first UE 115 should relay SLSS to other UEs 115 within a wireless communication system. In particular, by comparing measurements performed at multiple TRPs with one or more measurement thresholds, the first UE 115-g can efficiently determine whether the first UE 115-g should become a SyncRef UE 115 to improve the distribution of SLSS throughout the system. Thus, by improving the efficiency and reliability of SLSS distribution, the techniques described herein can improve clock synchronization among UEs 115 within a wireless communication system (e.g., wireless communication system 100, 200, or 300), thereby obtaining improved wireless communication and an improved user experience.

[0153] Figure 5 In accordance with aspects of the present disclosure, a block diagram 500 of a device 505 that supports techniques for SLSS transmission with a multi-TRP UE is shown. The device 505 may be an example of some aspects of a UE 115 as described herein. The device 505 may include a receiver 510, a transmitter 515, and a communication manager 520. The device 505 may also include a processor. Each of these components may communicate with one another (e.g., via one or more buses).

[0154] The receiver 510 may provide a unit for receiving information such as packets, user data, or control information associated with respective information channels (e.g., control channels, data channels, information related to techniques for SLSS transmission with a multi-TRP UE). The information may be conveyed to other components of the device 505. The receiver 510 may utilize a single antenna or multiple antennas.

[0155] The transmitter 515 may provide a unit for transmitting signals generated by other components of the device 505. In some examples, the transmitter 515 may be collocated with the receiver 510 in a transceiver module. The transmitter 515 may utilize a single antenna or may also utilize multiple antennas.

[0156] The communication manager 520, the receiver 510, the transmitter 515, or various combinations or various components thereof may be examples of units for performing various aspects of the techniques for SLSS transmission with a multi-TRP UE as described herein.

[0157] In some examples, the communication manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be implemented using hardware (e.g., implemented using a communication management circuit). The hardware may include a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof, which are designed to perform the functions described in the present disclosure.

[0158] Additionally or alternatively, in some examples, the communication manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be implemented using code executed by a processor (e.g., implemented as communication management software or firmware). If implemented using code executed by a processor, the functions of the communication manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be performed by a general purpose processor, a DSP, a CPU, an ASIC, an FPGA, or some other programmable logic device.

[0159] In some examples, the communication manager 520 may be configured to use the receiver 510, the transmitter 515, or both, or otherwise cooperate with them to perform various operations (e.g., receive, monitor, transmit).

[0160] According to examples disclosed herein, the communication manager 520 may support wireless communication at a first UE. For example, the communication manager 520 may be configured to provide or support: a unit for receiving a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP. The communication manager 520 may be configured to provide or support: a unit for performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. The communication manager 520 may be configured to provide or support: a unit for transmitting a second SLSS to a third UE at least in part based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

[0161] By including or configuring the communication manager 520 according to the examples described herein, the device 505 can support techniques for improving sidelink synchronization signal (SLSS) transmission and reception in the context of a multi-transmission and reception point (TRP) user equipment (UE) 115. For example, by improving the determination of whether the multi-TRP UE 115 should relay received SLSS, the distribution of SLSS within a wireless communication system can be improved. Additionally, determining which TRPs should be used to relay SLSS can further improve SLSS distribution. By improving the distribution of SLSS within a wireless communication system, the internal clocks of UEs 115 within the wireless communication system 100 can be improved, resulting in more efficient and reliable wireless communication, reducing the number of retransmissions that may be required, and improving the user experience.

[0162] Based on a determination of whether to relay SLSS, a processor of the multi-TRP UE 115 (e.g., the processors controlling the receiver 510, communication manager 520, transmitter 515, etc.) can reduce the processing resources used for wireless communication. For example, by improving the distribution of SLSS within a wireless communication system, the clock synchronization between UEs 115 within a wireless communication network can be improved. Improved clock synchronization between UEs 115 can increase the efficiency and reliability of sidelink transmissions exchanged between UEs 115 and with the base station 105, thereby reducing the number of retransmissions that must be performed and reducing network overhead. Additionally, by improving clock synchronization and reducing the amount of retransmissions, the techniques described herein can reduce the frequency at which the processors of the multi-TRP UE 115 must ramp up to handle signal transmission and reception, thereby reducing processing resources, reducing power consumption, and improving battery performance.

[0163] Figure 6 In accordance with aspects of the present disclosure, a block diagram 600 of a device 605 supporting techniques for SLSS transmission with a multi-TRP UE is shown. The device 605 can be an example of some aspects of the device 505 or UE 115 as described herein. The device 605 can include a receiver 610, a transmitter 615, and a communication manager 620. The device 605 can also include a processor. Each of these components can communicate with one another (e.g., via one or more buses).

[0164] The receiver 610 can provide units for receiving information such as packets, user data, or control information associated with respective information channels (e.g., control channels, data channels, information related to techniques for SLSS transmission with a multi-TRP UE). The information can be communicated to other components of the device 605. The receiver 610 can utilize a single antenna or multiple antennas.

[0165] The transmitter 615 can provide a unit for transmitting signals generated by other components of the device 605. In some examples, the transmitter 615 can be collocated with the receiver 610 in a transceiver module. The transmitter 615 can utilize a single antenna or can also utilize multiple antennas.

[0166] The device 605 or its various components can be examples of units for performing various aspects of the techniques for SLSS transmission with a multi-TRP UE as described herein. For example, the communication manager 620 can include an SLSS reception manager 625, an SLSS measurement manager 630, an SLSS transmission manager 635, or any combination thereof. The communication manager 620 can be an example of aspects of the communication manager 520 as described herein. In some examples, the communication manager 620 or its various components can be configured to use the receiver 610, the transmitter 615, or both, or otherwise cooperate with them to perform various operations (e.g., receive, monitor, transmit).

[0167] According to examples disclosed herein, the communication manager 620 can support wireless communication at a first UE. The SLSS reception manager 625 can be configured to provide or support: a unit for receiving a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP. The SLSS measurement manager 630 can be configured to provide or support: a unit for performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. The SLSS transmission manager 635 can be configured to provide or support: a unit for transmitting a second SLSS to a third UE based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

[0168] Figure 7 According to aspects of the present disclosure, a block diagram 700 of a communication manager 720 that supports techniques for SLSS transmission with a multi-TRP UE is shown. The communication manager 720 can be an example of some aspects of the communication manager 520, the communication manager 620, or both as described herein. The communication manager 720 or its various components can be examples of units for performing various aspects of the techniques for SLSS transmission with a multi-TRP UE as described herein. For example, the communication manager 720 can include an SLSS reception manager 725, an SLSS measurement manager 730, an SLSS transmission manager 735, a timer manager 740, a resource manager 745, a beam direction manager 750, a control message reception manager 755, an empty transmission manager 760, or any combination thereof. Each of these components can communicate directly or indirectly with each other (e.g., via one or more buses).

[0169] According to examples disclosed herein, the communication manager 720 may support wireless communication at a first UE. The SLSS reception manager 725 may be configured to provide or support: a unit for receiving a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP. The SLSS measurement manager 730 may be configured to provide or support: a unit for performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. The SLSS transmission manager 735 may be configured to provide or support: a unit for sending a second SLSS to a third UE based on the first set of measurements, the second set of measurements, or both meeting one or more measurement thresholds.

[0170] In some examples, the SLSS measurement manager 730 may be configured to provide or support: a unit for determining that the first set of measurements fails to meet the one or more measurement thresholds. In some examples, the SLSS measurement manager 730 may be configured to provide or support: a unit for determining that the second set of measurements meets the one or more measurement thresholds. In some examples, the SLSS transmission manager 735 may be configured to provide or support: a unit for using the second TRP to send the second SLSS based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

[0171] In some examples, the SLSS transmission manager 735 may be configured to provide or support: a unit for avoiding using the first TRP to send the second SLSS based on determining that the first set of measurements fails to meet the one or more measurement thresholds.

[0172] In some examples, the SLSS transmission manager 735 may be configured to provide or support: a unit for using the first TRP to send the second SLSS based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

[0173] In some examples, the first set of measurements, the second set of measurements, or both include received signal strength indicator measurements, reference signal received power measurements, reference signal received quality measurements, or any combination thereof.

[0174] In some examples, the one or more measurement thresholds include received signal strength indicator thresholds, reference signal received power thresholds, reference signal received quality thresholds, or any combination thereof. In some examples, if the first set of measurements, the second set of measurements, or both are less than or equal to the corresponding measurement thresholds, then the first set of measurements, the second set of measurements, or both meet the corresponding measurement thresholds.

[0175] In some examples, the SLSS measurement manager 730 may be configured to provide or support: a unit for determining that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds. In some examples, the timer manager 740 may be configured to provide or support: a unit for starting one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold. In some examples, the timer manager 740 may be configured to provide or support: a unit for determining the expiration of the one or more timers based on starting the one or more timers, wherein transmitting the second SLSS is based on determining the expiration of the one or more timers.

[0176] In some examples, to start the one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold, the timer manager 740 may be configured to provide or support: a unit for starting a first timer associated with a first TRP based on determining that the first set of measurements meets the first measurement threshold. In some examples, to start the one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold, the timer manager 740 may be configured to provide or support: a unit for starting a second timer associated with a second TRP based on determining that the second set of measurements meets the first measurement threshold.

[0177] In some examples, to transmit the second SLSS, the SLSS transmission manager 735 may be configured to provide or support: a unit for transmitting the second SLSS using a first TRP based on determining the expiration of a first timer associated with the first TRP. In some examples, to transmit the second SLSS, the SLSS transmission manager 735 may be configured to provide or support: a unit for transmitting the second SLSS using a second TRP based on determining the expiration of a second timer associated with the second TRP.

[0178] In some examples, the SLSS measurement manager 730 may be configured to provide or support: a unit for determining that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds. In some examples, the timer manager 740 may be configured to provide or support: a unit for starting one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold. In some examples, the timer manager 740 may be configured to provide or support: a unit for deactivating the one or more timers based on determining that the first set of measurements, the second set of measurements, or both meet a second measurement threshold among the one or more measurement thresholds, where the second measurement threshold is different from the first measurement threshold. In some examples, the SLSS transmission manager 735 may be configured to provide or support: a unit for avoiding transmitting a second SLSS based on deactivating the one or more timers.

[0179] In some examples, the resource manager 745 may be configured to provide or support: a unit for determining a resource set associated with the first SLSS, the second SLSS, or both, where transmitting the second SLSS is based on determining the resource set.

[0180] In some examples, the SLSS reception manager 725 may be configured to provide or support: a unit for receiving the first SLSS using a first subset of the resource set based on determining the resource set. In some examples, the SLSS transmission manager 735 may be configured to provide or support: a unit for transmitting the second SLSS using a second subset of the resource set that is different from the first subset based on determining the resource set.

[0181] In some examples, the control message reception manager 755 may be configured to provide or support: a unit for receiving a control message including an indication of the resource set from a base station, where determining the resource set is based on receiving the control message.

[0182] In some examples, for transmitting the second SLSS, the SLSS transmission manager 735 may be configured to provide or support: a unit for transmitting the second SLSS according to the resource set using a TRP selected from a first TRP and a second TRP. In some examples, for transmitting the second SLSS, the null transmission manager 760 may be configured to provide or support: a unit for transmitting a null value according to the resource set using a first TRP or a second TRP that is different from the selected TRP.

[0183] In some examples, the beam direction manager 750 may be configured to provide or support: a unit for estimating the beam direction of the first SLSS based on the first set of measurements and the second set of measurements, where the second SLSS is transmitted based on the estimated beam direction.

[0184] In some examples, the SLSS transmission manager 735 can be configured to provide or support: a unit for transmitting a second SLSS along a second beam direction equal to the estimated beam direction.

[0185] Figure 8 In accordance with aspects of the present disclosure, a diagram of a system 800 including a device 805 is shown, where the device 805 supports techniques for SLSS transmission with a multi-TRP UE. The device 805 can be an example of the device, device 605, or UE 115 described herein, or include components of the device, device 605, or UE 115. The device 805 can communicate wirelessly with one or more base stations 105, UEs 115, or any combination thereof. The device 805 can include components for two-way voice and data communication, which include components for transmitting communication and components for receiving communication, including a communication manager 810, an I / O controller 815, a transceiver 820, an antenna 825, a memory 830, code 835, and a processor 840. These components can communicate electrically or otherwise be coupled (e.g., operatively, communicatively, functionally, electronically, and / or electrically coupled) via one or more buses (e.g., bus 845).

[0186] The I / O controller 815 can manage input and output signals for the device 805. The I / O controller 815 can also manage peripheral devices not integrated into the device 805. In some cases, the I / O controller 815 can represent a physical connection or port for external peripheral devices. In some cases, the I / O controller 815 can utilize an operating system such as or another known operating system. In other cases, the I / O controller 815 can represent a modem, keyboard, mouse, touch screen, or similar device, or interact with these devices. In some cases, the I / O controller 815 can be implemented as part of a processor. In some cases, a user can interact with the device 805 via the I / O controller 815 or via hardware components controlled by the I / O controller 815.

[0187] In some cases, the device 805 may include a single antenna 825. However, in some cases, the device may have more than one antenna 825 that can simultaneously transmit or receive multiple wireless transmissions. The transceiver 820 can communicate bidirectionally via one or more antennas 825, a wired link, or a wireless link, as described herein. For example, the transceiver 820 may represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 820 may also include a modem to modulate packets, provide the modulated packets to one or more antennas 825 for transmission, and demodulate packets received from one or more antennas 825. The transceiver 820 or the transceiver 820 and one or more antennas 825 may be examples of the transmitter 515, the transmitter 615, the receiver 610, or any combination thereof or components thereof, as described herein.

[0188] The memory 830 may include random access memory (RAM) and read only memory (ROM). The memory 830 may store computer-readable, computer-executable code 835 that includes instructions that, when executed by the processor 840, cause the device 805 to perform the various functions described herein. The code 835 may be stored in a non-transitory computer-readable medium such as system memory or other types of memory. In some cases, the code 835 may not be directly executable by the processor 840 but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, specifically, the memory 830 may contain a basic input / output system (BIOS) that may control basic hardware or software operations (e.g., interactions with peripheral components or devices).

[0189] The processor 840 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, central processing units (CPUs), microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 840 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 840. The processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 830) to cause the device 805 to perform various functions (e.g., functions or tasks that support techniques for SLSS transmission with multi-TRP UEs).

[0190] According to examples disclosed herein, communication manager 810 may support wireless communication at a first UE. For example, communication manager 820 may be configured to provide or support: a unit for receiving a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP. Communication manager 810 may be configured to provide or support: a unit for performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. Communication manager 810 may be configured to provide or support: a unit for sending a second SLSS to a third UE based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

[0191] By including or configuring communication manager 810 according to the examples described herein, device 805 may support improved techniques for enhancing SLSS transmission and reception, which may thereby improve battery performance and enhance the user experience. For example, by improving the determination of whether multi-TRP UE 115 should relay a received SLSS, the distribution of SLSS within a wireless communication system may be improved. Additionally, determining which TRPs should be used to relay SLSS may further improve SLSS distribution. By improving the distribution of SLSS within a wireless communication system, the internal clock of UE 115 within wireless communication system 100 may be improved, resulting in more efficient and reliable wireless communication, reducing the number of retransmissions that may be required, and enhancing the user experience. Specifically, by improving clock synchronization and reducing the amount of retransmissions, the techniques described herein may reduce the frequency with which the processor of multi-TRP UE 115 must ramp up to handle signal transmission and reception, thereby reducing processing resources, reducing power consumption, and improving battery performance.

[0192] In some examples, communication manager 810 may be configured to use transceiver 820, one or more antennas 825, or any combination thereof, or otherwise cooperate with them to perform various operations (e.g., receive, monitor, transmit). Although communication manager 810 is shown as a separate component, in some examples, one or more functions described with reference to communication manager 810 may be supported or performed by processor 840, memory 830, code 835, or any combination thereof. For example, code 835 may include instructions executable by processor 840 to cause device 805 to perform various aspects of the techniques for SLSS transmission with multi-TRP UEs as described herein, or processor 840 and memory 830 may otherwise be configured to perform or support such operations.

[0193] Figure 9In accordance with aspects of the present disclosure, a flowchart depicting a method 900 for techniques supporting SLSS transmissions for multi-TRP UEs is shown. Operations of method 900 may be implemented by a UE or components thereof as described herein. For example, operations of method 900 may be performed by UE 115 as described with reference to Figures 1 to 8 as described. In some examples, a UE may execute a set of instructions to control functional units of the device to perform the described functions. Additionally or alternatively, the UE may use special-purpose hardware to perform aspects of the described functions.

[0194] At 905, the method may include: receiving, at a first TRP and a second TRP different from the first TRP, a first SLSS from a second UE. The operation at 905 may be performed according to methods as described herein. In some examples, aspects of the operation at 905 may be performed by an SLSS reception manager 725 as described with reference to Figure 7 as described.

[0195] At 910, the method may include: performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. The operation at 910 may be performed according to methods as described herein. In some examples, aspects of the operation at 910 may be performed by an SLSS measurement manager 730 as described with reference to Figure 7 as described.

[0196] At 915, the method may include: transmitting, to a third UE, a second SLSS based at least in part on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds. The operation at 915 may be performed according to methods as described herein. In some examples, aspects of the operation at 915 may be performed by an SLSS transmission manager 735 as described with reference to Figure 7 as described.

[0197] Figure 10 In accordance with aspects of the present disclosure, a flowchart depicting a method 1000 for techniques supporting SLSS transmissions for multi-TRP UEs is shown. Operations of method 1000 may be implemented by a UE or components thereof as described herein. For example, operations of method 1000 may be performed by UE 115 as described with reference to Figures 1 to 8 as described. In some examples, a UE may execute a set of instructions to control functional units of the device to perform the described functions. Additionally or alternatively, the UE may use special-purpose hardware to perform aspects of the described functions.

[0198] At 1005, the method may include: receiving, at a first TRP and a second TRP different from the first TRP, a first SLSS from a second UE. The operation of 1005 may be performed according to the methods described herein. In some examples, aspects of the operation of 1005 may be performed by an SLSS reception manager 725 as described with reference to Figure 7 as described.

[0199] At 1010, the method may include: performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. The operation of 1010 may be performed according to the methods described herein. In some examples, aspects of the operation of 1010 may be performed by an SLSS measurement manager 730 as described with reference to Figure 7 as described.

[0200] At 1015, the method may include: determining that the first set of measurements fails to meet the one or more measurement thresholds. The operation of 1015 may be performed according to the methods described herein. In some examples, aspects of the operation of 1015 may be performed by an SLSS measurement manager 730 as described with reference to Figure 7 as described.

[0201] At 1020, the method may include: determining that the second set of measurements meets the one or more measurement thresholds. The operation of 1020 may be performed according to the methods described herein. In some examples, aspects of the operation of 1020 may be performed by an SLSS measurement manager 730 as described with reference to Figure 7 as described.

[0202] At 1025, the method may include: using the second TRP to transmit a second SLSS, at least in part based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both. The operation of 1025 may be performed according to the methods described herein. In some examples, aspects of the operation of 1025 may be performed by an SLSS transmission manager 735 as described with reference to Figure 7 as described.

[0203] At 1030, the method may include: avoiding using the first TRP to transmit the second SLSS, at least in part based on determining that the first set of measurements fails to meet the one or more measurement thresholds. The operation of 1030 may be performed according to the methods described herein. In some examples, aspects of the operation of 1030 may be performed by an SLSS transmission manager 735 as described with reference to Figure 7 as described.

[0204] Figure 11In accordance with aspects of the present disclosure, a flowchart depicting method 1100 that supports techniques for SLSS transmission with a multi-TRP UE is shown. Operations of method 1100 may be implemented by a UE or components thereof as described herein. For example, operations of method 1100 may be performed by UE 115 as described with reference to Figures 1 to 8 In some examples, the UE may execute a set of instructions to control functional units of the device to perform the described functions. Additionally or alternatively, the UE may use special-purpose hardware to perform aspects of the described functions.

[0205] At 1105, the method may include: receiving a first SLSS from a second UE at a first TRP and a second TRP different from the first TRP. The operation of 1105 may be performed according to the methods described herein. In some examples, aspects of the operation of 1105 may be performed by an SLSS reception manager 725 as described with reference to Figure 7 In some examples, aspects of the operation of 1105 may be performed by an SLSS reception manager 725 as described with reference to

[0206] At 1110, the method may include: performing a first set of measurements on the first SLSS received at the first TRP and a second set of measurements on the first SLSS received at the second TRP. The operation of 1110 may be performed according to the methods described herein. In some examples, aspects of the operation of 1110 may be performed by an SLSS measurement manager 730 as described with reference to Figure 7 In some examples, aspects of the operation of 1110 may be performed by an SLSS measurement manager 730 as described with reference to

[0207] At 1115, the method may include: determining that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds. The operation of 1115 may be performed according to the methods described herein. In some examples, aspects of the operation of 1115 may be performed by an SLSS measurement manager 730 as described with reference to Figure 7 In some examples, aspects of the operation of 1115 may be performed by an SLSS measurement manager 730 as described with reference to

[0208] At 1120, the method may include: starting one or more timers at least in part based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold. The operation of 1120 may be performed according to the methods described herein. In some examples, aspects of the operation of 1120 may be performed by a timer manager 740 as described with reference to Figure 7 In some examples, aspects of the operation of 1120 may be performed by a timer manager 740 as described with reference to

[0209] At 1125, the method may include: determining an expiration of the one or more timers at least in part based on starting the one or more timers. The operation of 1125 may be performed according to the methods described herein. In some examples, aspects of the operation of 1125 may be performed by a timer manager 740 as described with reference to Figure 7performed by the described timer manager 740.

[0210] At 1130, the method may include: sending a second SLSS to a third UE based at least in part on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds, wherein sending the second SLSS depends at least in part on determining the expiration of the one or more timers. The operations of 1130 may be performed according to the methods described herein. In some examples, aspects of the operations of 1130 may be performed by the SLSS transmission manager 735 as described with reference to Figure 7 the described SLSS transmission manager 735.

[0211] It should be noted that the methods described herein describe possible implementations, and these operations and steps may be rearranged or modified, and other implementations are also possible. In addition, two or more aspects from these methods may be combined.

[0212] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems are described for purposes of illustration and the terms LTE, LTE-A, LTE-A Pro, or NR are used in most of the description, the techniques described herein are also applicable outside of LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to a variety of other wireless communication systems such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0213] The information and signals described herein may be represented using any of a variety of different technologies and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the description herein may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0214] A general-purpose processor, DSP, ASIC, CPU, FPGA, or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any combination thereof for performing the functions described herein may be used to implement or perform the various exemplary blocks and components described in connection with the disclosure herein. The general-purpose processor may be a microprocessor, or alternatively, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, several microprocessors, a combination of a microprocessor and a DSP core, or any other such configuration).

[0215] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. When implemented in software executed by a processor, the functions can be stored on a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Other examples and implementations also fall within the scope of the present disclosure and its appended claims. For example, due to the nature of software, the functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features for implementing the functions can be physically distributed at various locations, including being distributed at different physical locations to implement a part of the functions.

[0216] Computer-readable media includes non-transitory computer storage media and communication media, where communication media includes any medium that facilitates transfer of a computer program from one place to another. The non-transitory storage media can be any available medium accessible by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code units in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Additionally, any connection can be properly termed a computer-readable medium. By way of example, if software is transmitted using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the computer-readable medium. As used herein, disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically, while discs optically reproduce data with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0217] As used herein (including in the claims), the term "or" as used in a list item (e.g., a list item that ends with a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such that a list of at least one of A, B, or C, for example, means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Further, as used herein, the phrase "based on" should not be construed as referring to a closed set of one or more conditions. For example, an exemplary step described as "based on condition A" may be based on condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "at least partially based on".

[0218] In the drawings, like reference numerals designate like parts or features. Additionally, each of the same type of parts may be distinguished by following the reference numeral with a dashed line and a second numeral used to distinguish similar parts. If only the first reference numeral is used in the specification, the description may apply to any of the similar parts having the same first reference numeral, regardless of any subsequent reference numerals.

[0219] The specific embodiments described herein in conjunction with the drawings describe exemplary configurations, but they do not represent all examples that can be implemented, nor all examples that fall within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration", but does not mean "more preferred" or "more advantageous" than other examples. The specific embodiments include specific details for providing a thorough understanding of the described techniques. However, the techniques may be implemented without using these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0220] The foregoing has been described around the present disclosure to enable any ordinary person skilled in the art to implement or use the present disclosure. Various modifications to the present disclosure are obvious to those of ordinary skill in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is consistent with the broadest scope of the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a first user equipment (UE), comprising: Receive a first sidelink synchronization signal from a second UE at a first transmission reception point (TRP) and a second TRP different from the first TRP; Perform a first set of measurements on the first sidelink synchronization signal received at the first TRP, and perform a second set of measurements on the first sidelink synchronization signal received at the second TRP; Send a second sidelink synchronization signal to a third UE at least in part based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

2. The method according to claim 1, further comprising: Determine that the first set of measurements fails to meet the one or more measurement thresholds; Determine that the second set of measurements meets the one or more measurement thresholds; And Use the second TRP to send the second sidelink synchronization signal at least in part based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

3. The method according to claim 2, further comprising: Avoid using the first TRP to send the second sidelink synchronization signal at least in part based on determining that the first set of measurements fails to meet the one or more measurement thresholds.

4. The method according to claim 2, further comprising: Use the first TRP to send the second sidelink synchronization signal at least in part based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

5. The method according to claim 1, wherein, The first set of measurements, the second set of measurements, or both include received signal strength indicator measurements, reference signal received power measurements, reference signal received quality measurements, or any combination thereof.

6. The method according to claim 5, wherein, The one or more measurement thresholds include a received signal strength indicator threshold, a reference signal received power threshold, a reference signal received quality threshold, or any combination thereof, If the first set of measurements, the second set of measurements, or both are less than or equal to the corresponding measurement thresholds, then the first set of measurements, the second set of measurements, or both meet the corresponding measurement thresholds.

7. The method according to claim 1, further comprising: Determine that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds; Start one or more timers at least in part based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold; And Determine the expiration of the one or more timers at least in part based on starting the one or more timers, wherein sending the second sidelink synchronization signal is at least in part based on determining the expiration of the one or more timers.

8. The method according to claim 7, wherein, Starting the one or more timers at least in part based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold includes: Starting a first timer associated with the first TRP at least in part based on determining that the first set of measurements meets the first measurement threshold; and Starting a second timer associated with the second TRP at least in part based on determining that the second set of measurements meets the first measurement threshold.

9. The method according to claim 8, wherein, Sending the second sidelink synchronization signal includes: Transmit the second sidelink synchronization signal using the first TRP, at least partially based on determining the expiration of the first timer associated with the first TRP; and Transmit the second sidelink synchronization signal using the second TRP, at least partially based on determining the expiration of the second timer associated with the second TRP.

10. The method according to claim 1, further comprising: Determine that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds; Start one or more timers, at least partially based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold; Deactivate the one or more timers, at least partially based on determining that the first set of measurements, the second set of measurements, or both meet a second measurement threshold among the one or more measurement thresholds, the second measurement threshold being different from the first measurement threshold; And Avoid transmitting the second sidelink synchronization signal, at least partially based on deactivating the one or more timers.

11. The method according to claim 1, further comprising: Determine a resource set associated with the first sidelink synchronization signal, the second sidelink synchronization signal, or both, wherein transmitting the second sidelink synchronization signal is at least partially based on determining the resource set.

12. The method according to claim 11, further comprising: Receive the first sidelink synchronization signal using a first subset of the resource set, at least partially based on determining the resource set; And Transmit the second sidelink synchronization signal using a second subset of the resource set that is different from the first subset of the resource set, at least partially based on determining the resource set.

13. The method according to claim 11, further comprising: Receive a control message from a base station that includes an indication of the resource set, wherein determining the resource set is at least partially based on receiving the control message.

14. The method according to claim 11, wherein, Transmitting the second sidelink synchronization signal includes: Transmitting the second sidelink synchronization signal according to the resource set using a TRP selected from the first TRP and the second TRP; and Transmitting a null value according to the resource set using the first TRP or the second TRP that is different from the selected TRP.

15. The method according to claim 1, further comprising: Estimate a beam direction of the first sidelink synchronization signal, at least partially based on the first set of measurements and the second set of measurements, wherein the second sidelink synchronization signal is transmitted at least partially based on the estimated beam direction.

16. The method according to claim 15, further comprising: Transmit the second sidelink synchronization signal along a second beam direction equal to the estimated beam direction.

17. An apparatus for wireless communication at a first user equipment (UE), 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 following operations: Receive a first sidelink synchronization signal from a second UE at a first transmission reception point (TRP) and a second TRP different from the first TRP; Perform a first set of measurements on the first sidelink synchronization signal received at the first TRP and a second set of measurements on the first sidelink synchronization signal received at the second TRP; Send a second sidelink synchronization signal to a third UE at least partially based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

18. The apparatus according to claim 17, wherein, The instructions may also be executed by the processor to cause the device to perform the following operations: Determine that the first set of measurements fails to meet the one or more measurement thresholds; Determine that the second set of measurements meets the one or more measurement thresholds; And Use the second TRP to send the second sidelink synchronization signal at least partially based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

19. The apparatus according to claim 18, wherein, The instructions may also be executed by the processor to cause the device to perform the following operations: Avoid using the first TRP to send the second sidelink synchronization signal at least partially based on determining that the first set of measurements fails to meet the one or more measurement thresholds.

20. The apparatus according to claim 18, wherein, The instructions may also be executed by the processor to cause the device to perform the following operations: Use the first TRP to send the second sidelink synchronization signal at least partially based on determining that the first set of measurements fails to meet the one or more measurement thresholds, determining that the second set of measurements meets the one or more measurement thresholds, or both.

21. The apparatus according to claim 17, wherein, The first set of measurements, the second set of measurements, or both include received signal strength indicator measurements, reference signal received power measurements, reference signal received quality measurements, or any combination thereof.

22. The apparatus according to claim 21, wherein, The one or more measurement thresholds include a received signal strength indicator threshold, a reference signal received power threshold, a reference signal received quality threshold, or any combination thereof. If the first set of measurements, the second set of measurements, or both are less than or equal to the corresponding measurement threshold, then the first set of measurements, the second set of measurements, or both meet the corresponding measurement threshold.

23. The device according to claim 17, wherein, The instructions may also be executed by the processor to cause the device to perform the following operations: Determine that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds; Start one or more timers at least partially based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold; And Determine the expiration of the one or more timers at least partially based on starting the one or more timers, wherein sending the second sidelink synchronization signal is at least partially based on determining the expiration of the one or more timers.

24. The device according to claim 23, wherein, The instructions for starting the one or more timers at least partially based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold may be executed by the processor to cause the device to perform the following operations: Start a first timer associated with the first TRP at least partially based on determining that the first set of measurements meets the first measurement threshold; and Start a second timer associated with the second TRP at least partially based on determining that the second set of measurements meets the first measurement threshold.

25. The device according to claim 24, wherein, The instruction for sending the second sidelink synchronization signal can be executed by the processor to cause the device to perform the following operations: Use the first TRP to send the second sidelink synchronization signal, at least partially based on determining the expiration of the first timer associated with the first TRP; and Use the second TRP to send the second sidelink synchronization signal, at least partially based on determining the expiration of the second timer associated with the second TRP.

26. The device according to claim 17, wherein, The instruction can also be executed by the processor to cause the device to perform the following operations: Determine that the first set of measurements, the second set of measurements, or both meet a first measurement threshold among the one or more measurement thresholds; Start one or more timers, at least partially based on determining that the first set of measurements, the second set of measurements, or both meet the first measurement threshold; Deactivate the one or more timers, at least partially based on determining that the first set of measurements, the second set of measurements, or both meet a second measurement threshold among the one or more measurement thresholds, where the second measurement threshold is different from the first measurement threshold; And Avoid sending the second sidelink synchronization signal, at least partially based on deactivating the one or more timers.

27. The device according to claim 17, wherein, The instruction can also be executed by the processor to cause the device to perform the following operations: Determine a resource set associated with the first sidelink synchronization signal, the second sidelink synchronization signal, or both, where sending the second sidelink synchronization signal is at least partially based on determining the resource set.

28. The device according to claim 27, wherein, The instruction can also be executed by the processor to cause the device to perform the following operations: Receive the first sidelink synchronization signal using a first subset of the resource set, at least partially based on determining the resource set; And Send the second sidelink synchronization signal using a second subset of the resource set that is different from the first subset, at least partially based on determining the resource set.

29. The device according to claim 27, wherein, The instruction can also be executed by the processor to cause the device to perform the following operations: Receive a control message from the base station that includes an indication of the resource set, where determining the resource set is at least partially based on receiving the control message.

30. The device according to claim 27, wherein, The instruction for sending the second sidelink synchronization signal can be executed by the processor to cause the device to perform the following operations: Use a TRP selected from the first TRP and the second TRP to send the second sidelink synchronization signal according to the resource set; And Send a null value according to the resource set using the first TRP or the second TRP that is different from the selected TRP.

31. The device according to claim 17, wherein, The instruction can also be executed by the processor to cause the device to perform the following operations: Estimate the beam direction of the first sidelink synchronization signal, at least partially based on the first set of measurements and the second set of measurements, where the second sidelink synchronization signal is sent at least partially based on the estimated beam direction.

32. The device according to claim 31, wherein, The instruction can also be executed by the processor to cause the device to perform the following operations: Transmit the second sidelink synchronization signal along a second beam direction equal to the estimated beam direction.

33. An apparatus for wireless communication at a first user equipment (UE), comprising: A unit for receiving a first sidelink synchronization signal from a second UE at a first transmission reception point (TRP) and a second TRP different from the first TRP; A unit for performing a first set of measurements on the first sidelink synchronization signal received at the first TRP and a second set of measurements on the first sidelink synchronization signal received at the second TRP; A unit for transmitting a second sidelink synchronization signal to a third UE at least partially based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

34. A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by a processor to perform the following operations: Receive a first sidelink synchronization signal from a second UE at a first transmission reception point (TRP) and a second TRP different from the first TRP; Perform a first set of measurements on the first sidelink synchronization signal received at the first TRP and a second set of measurements on the first sidelink synchronization signal received at the second TRP; Transmit a second sidelink synchronization signal to a third UE at least partially based on the first set of measurements, the second set of measurements, or both satisfying one or more measurement thresholds.

Images