Techniques for Selecting and Reselecting Sidelink Relays

Abstract

Methods, systems, and devices for wireless communication are described. A user equipment (UE) may determine to operate as a relay UE based on a set of thresholds configured for a first UE. The UE may send a relay discovery announcement on a communication channel of a sidelink to indicate support for relay communication. A remote UE may monitor and receive the relay discovery announcement on the sidelink communication channel. The remote UE may select a relay UE based on a set of criteria for selecting a candidate relay UE. The remote UE and the relay UE may establish relay communication based on the relay discovery announcement sent on the communication channel of the relay sidelink.

Description

Technical Field

[0001] Generally speaking, the following relates to wireless communication, and more specifically, the following relates to techniques for selecting and reselecting sidelink relays. Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasting, etc. These systems are capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multi-access systems include fourth-generation (4G) systems (e.g., Long Term Evolution (LTE) systems, enhanced LTE (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 simultaneously supports communication for multiple communication devices (which may alternatively be referred to as user equipment (UE)).

[0003] A UE in a wireless communication system may operate as a relay node for a remote UE, which transmits traffic so that the remote UE can communicate with a base station. The relay UE may provide a relay sidelink for the remote UE, and the relay UE may communicate with the base station using a cellular link. Techniques for selecting and reselecting relay UEs may be improved. Summary of the Invention

[0004] The described techniques relate to improved methods, systems, devices, and apparatuses that support techniques for selecting and reselecting sidelink repeaters. Generally speaking, the described techniques provide for using a communication channel of a sidelink repeater to transmit a relay discovery message. A user equipment (UE) in a wireless communication system may operate as a relay node for a remote UE, and it transmits traffic so that the remote UE can communicate with a base station. The relay UE may provide a relay sidelink for the remote UE, and the relay UE may communicate with the base station using a cellular link. The relay UE may be within the coverage of the base station, while the remote UE may be within or outside the coverage. In some cases, the remote UE may select the relay UE. For example, the remote UE may identify that there is at least one candidate relay UE in the vicinity of the remote UE. In some cases, the relay UE may announce its presence by sending a discovery message. In some examples, the remote UE may send a relay request message. The nearby candidate relay UEs may receive the relay request message and send a relay discovery message. The remote UE may detect the candidate relay UEs based on the relay discovery message. The nearby repeater may receive the discovery solution message and respond to establish a relay sidelink.

[0005] The wireless communication system described herein supports enhanced techniques for sidelink relay selection and reselection. In some cases, these techniques may enable a remote UE to identify and select or reselect candidate relay UEs by transmitting a relay discovery message on a communication channel of the relay sidelink. For example, the relay UE and the remote UE may send and receive discovery messages on a communication channel of the relay sidelink, such as a sidelink shared channel or a sidelink control channel. In some cases, the base station may configure resources on the relay sidelink for the relay UE and the remote UE to send and receive relay discovery announcements and relay discovery requests. Thus, the wireless communication system can still provide for the relay UE and the remote UE to send discovery signaling without using a dedicated discovery channel. In addition, enhanced techniques are described for a UE to determine to operate as a relay UE and for a remote UE to select a candidate relay UE to establish a relay sidelink.

[0006] A method of wireless communication at a first UE is described. The method may include: determining to operate as a relay UE based on a set of thresholds configured for the first UE; transmitting, on a sidelink channel, a relay discovery announcement indicating support for relay communication based on the determination to operate as the relay UE; and establishing the relay communication with a second UE based on the transmission of the relay discovery announcement on the sidelink channel.

[0007] A device for wireless communication at a first UE is described. The device may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the device to perform the following operations: determine to operate as a relay UE based on a set of thresholds configured for the first UE; transmit, on a sidelink channel, a relay discovery announcement indicating support for relay communication based on the determination to operate as the relay UE; and establish the relay communication with a second UE based on the transmission of the relay discovery announcement on the sidelink channel.

[0008] Another device for wireless communication at a first UE is described. The device may include units for performing the following operations: determine to operate as a relay UE based on a set of thresholds configured for the first UE; transmit, on a sidelink channel, a relay discovery announcement indicating support for relay communication based on the determination to operate as the relay UE; and establish the relay communication with a second UE based on the transmission of the relay discovery announcement on the sidelink channel.

[0009] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to perform the following operations: determine to operate as a relay UE based on a set of thresholds configured for the first UE; transmit, on a sidelink channel, a relay discovery announcement indicating support for relay communication based on the determination to operate as the relay UE; and establish the relay communication with a second UE based on the transmission of the relay discovery announcement on the sidelink channel.

[0010] Some examples of the methods, devices, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for performing the following operation: receive, on the sidelink channel, a relay request for operating as the relay UE for the second UE, wherein the determination to operate as the relay UE may be based on receiving the relay request.

[0011] Some examples of the methods, devices, and non-transitory computer-readable media described herein may further include operations, features, units, or instructions for performing the following operation: indicate to the second UE load information for the first UE, battery information for the first UE, a quality of service level supported for the relay communication, or a combination thereof, wherein the relay request may be received based on the indication.

[0012] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a radio resource control message from a base station, the radio resource control message indicating a set of several threshold sets including the set of thresholds.

[0013] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the set of several threshold sets includes a first threshold set used when the first UE may not be connected to a remote UE, and a second threshold set used when the first UE may be connected to at least one remote UE.

[0014] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the difference between the high threshold and the low threshold in the first threshold set may be less than the difference between the high threshold and the low threshold in the second threshold set.

[0015] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the determination of operating as the relay UE may also be based on the mobility state of the first UE.

[0016] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: reporting reference signal measurements, load information for the first UE, battery information for the first UE, or any combination thereof to the base station; and receiving an indication for sending the relay discovery announcement from the base station based on the report.

[0017] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the load information includes the channel busy rate for the sidelink channel for the first UE.

[0018] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the reference signal measurements, the load information, the battery information, or any combination thereof may be sent in a measurement report for radio resource management.

[0019] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: indicating, based on the sending of the relay discovery announcement, the quality of service level supported by the first UE for the relay communication to the second UE.

[0020] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the quality of service level may be indicated by a media access control element or by application code associated with a discovery announcement message.

[0021] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: receiving a set of quality of service levels from a base station, wherein the relay discovery announcement may be sent on the sidelink channel based on the set of quality of service levels including the quality of service level of the relay communication.

[0022] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: receiving radio resource control configuration of a set of resources for sending the relay discovery announcement on the sidelink channel from a base station.

[0023] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: receiving downlink control information from a base station, the downlink control information scheduling a first UE for a set of resources for sending the relay discovery announcement on the sidelink channel.

[0024] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: sending a relay discovery announcement request to a base station, the relay discovery announcement request including the quality of service level supported by the first UE for the relay communication; and receiving a relay discovery announcement response to the relay discovery announcement request from the base station, wherein the sending of the relay discovery announcement may be based on receiving the relay discovery announcement response.

[0025] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: including an indicator in a packet data convergence protocol (PDCP) packet of the relay discovery announcement that the relay discovery announcement may be associated with relay discovery.

[0026] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: receiving a measurement report of the sidelink channel from a second UE on the sidelink channel based on L3 filtering of reference signal measurements.

[0027] A method of wireless communication at a second UE is described. The method may include: monitoring a relay discovery announcement on a sidelink channel to establish relay communication with a first UE operating as a relay UE, wherein the relay communication is associated with a quality of service level; receiving the relay discovery announcement from the first UE via broadcast on the sidelink channel, wherein the first UE supports the quality of service level for the relay communication; and establishing the relay communication with the first UE based on receiving the relay discovery announcement.

[0028] An apparatus for wireless communication at a second UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: monitor a relay discovery announcement on a sidelink channel to establish relay communication with a first UE operating as a relay UE, wherein the relay communication is associated with a quality of service level; receive the relay discovery announcement from the first UE via broadcast on the sidelink channel, wherein the first UE supports the quality of service level for the relay communication; and establish the relay communication with the first UE based on receiving the relay discovery announcement.

[0029] Another apparatus for wireless communication at a second UE is described. The apparatus may include units for: monitoring a relay discovery announcement on a sidelink channel to establish relay communication with a first UE operating as a relay UE, wherein the relay communication is associated with a quality of service level; receiving the relay discovery announcement from the first UE via broadcast on the sidelink channel, wherein the first UE supports the quality of service level for the relay communication; and establishing the relay communication with the first UE based on receiving the relay discovery announcement.

[0030] A non-transitory computer-readable medium storing code for wireless communication at a second UE is described. The code may include instructions executable by a processor to: monitor a relay discovery announcement on a sidelink channel to establish relay communication with a first UE operating as a relay UE, wherein the relay communication is associated with a quality of service level; receive the relay discovery announcement from the first UE via broadcast on the sidelink channel, wherein the first UE supports the quality of service level for the relay communication; and establish the relay communication with the first UE based on receiving the relay discovery announcement.

[0031] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: determining to establish relay communication with a base station; sending a relay discovery announcement request including a quality of service level for the relay communication; receiving a relay discovery announcement response based on the sending of the relay discovery announcement request; and sending, based on the relay discovery announcement response, a relay request for the first UE to operate as the relay UE on the sidelink channel, wherein the relay discovery announcement may be received based on sending the relay request.

[0032] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving an indication that the first UE supports the quality of service level for the relay communication.

[0033] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the indication may be received via a media access control element or through application code associated with a relay discovery message.

[0034] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: selecting the first UE as the relay UE for the relay communication.

[0035] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving an indication that the first UE supports the quality of service level for the relay communication, wherein the selection may be based on the indication.

[0036] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving an indication of the load of the first UE, wherein the first UE may be selected based on the load of the first UE being lower than a load threshold.

[0037] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a system information block including the load threshold.

[0038] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving an indication of the battery level of the first UE, where the first UE may be selected based on the battery level being higher than a battery threshold.

[0039] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving a system information block including the battery threshold.

[0040] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: determining that the third UE cannot support the quality of service level for the relay communication, where the relay communication may be established with the first UE based on the determination.

[0041] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the relay communication may be established with the first UE based on any of the following: the first UE providing the quality of service level for the relay communication, the load of the first UE satisfying a load threshold, the battery level of the first UE satisfying a battery threshold, or a combination thereof.

[0042] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: identifying, in the PDCP packet of the relay discovery announcement, an indicator that the relay discovery announcement may be associated with relay discovery.

[0043] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: measuring a reference signal received from a first UE; filtering the reference signal based on the identifier of the first UE; and sending a measurement report for the reference signal to the first UE based on the filtering.

[0044] A method of wireless communication at a base station is described. The method may include: receiving a relay discovery request message including a quality of service level for relay communication between a first UE and a second UE; sending a relay discovery response message including application code for relay discovery based on the quality of service level for the relay communication; configuring the first UE with a resource set for relay discovery announcement on a sidelink channel; and receiving data for the second UE from the first UE based on the relay communication between the first UE and the second UE.

[0045] Describes an apparatus for wireless communication at a base station. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to perform the following operations: receive a relay discovery request message including a quality of service level for relay communication between a first UE and a second UE; send a relay discovery response message including application code for relay discovery based on the quality of service level for the relay communication; configure the first UE on a sidelink channel with a resource set for relay discovery announcements on the sidelink channel; and receive data for the second UE from the first UE based on the relay communication between the first UE and the second UE.

[0046] Describes another apparatus for wireless communication at a base station. The apparatus may include units for performing the following operations: receive a relay discovery request message including a quality of service level for relay communication between a first UE and a second UE; send a relay discovery response message including application code for relay discovery based on the quality of service level for the relay communication; configure the first UE on a sidelink channel with a resource set for relay discovery announcements on the sidelink channel; and receive data for the second UE from the first UE based on the relay communication between the first UE and the second UE.

[0047] Describes a non - transitory computer - readable medium storing code for wireless communication at a base station. The code may include instructions executable by a processor to perform the following operations: receive a relay discovery request message including a quality of service level for relay communication between a first UE and a second UE; send a relay discovery response message including application code for relay discovery based on the quality of service level for the relay communication; configure the first UE on a sidelink channel with a resource set for relay discovery announcements on the sidelink channel; and receive data for the second UE from the first UE based on the relay communication between the first UE and the second UE.

[0048] Some examples of the methods, apparatuses, and non - transitory computer - readable media described herein may further include operations, features, units, or instructions for performing the following operation: send a radio resource control message to the first UE indicating a set of several threshold sets.

[0049] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the set of threshold sets includes a first threshold set used when the first UE may not be connected to a remote UE, and a second threshold set used when the first UE may be connected to at least one remote UE.

[0050] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the difference between the high threshold and the low threshold in the first threshold set may be less than the difference between the high threshold and the low threshold in the second threshold set.

[0051] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: receiving, from the first UE, reference signal measurements, load information for the first UE, battery information for the first UE, or any combination thereof; and sending, based on the reports, an indication to broadcast the relay discovery announcement for the first UE.

[0052] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the load information includes the channel busy rate for the sidelink channel for the first UE.

[0053] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the reference signal measurements, the load information, the battery information, or any combination thereof may be received in a measurement report for radio resource management.

[0054] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: configuring the first UE with a set of quality of service levels, wherein the first UE may be configured to perform discovery for the relay communication based on the set of quality of service levels including the quality of service level for the relay communication.

[0055] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following: indicating the quality of service level for the relay communication based on the application code for the relay discovery.

[0056] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, configuring the first UE with a resource set on the sidelink channel may also include operations, features, units, or instructions for performing the following: sending, via downlink control information, an indication that the resource set may be configured for discovery signaling.

[0057] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, configuring the first UE with a resource set on the sidelink channel may further include operations, features, units, or instructions for: sending an indication via radio resource control signaling that the resource set may be configured for discovery signaling.

[0058] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the relay discovery request message may be received from the first UE, and the relay discovery response message may be sent to the first UE.

[0059] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the relay discovery request message may be received from the second UE, and the relay discovery response message may be sent to the second UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 FIG. shows an example of a system for wireless communication that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure.

[0061] Figure 2 FIG. shows an example of a wireless communication system that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure.

[0062] Figure 3 FIG. shows an example of a process flow that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure.

[0063] Figure 4 FIG. shows an example of a process flow that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure.

[0064] Figure 5 and Figure 6 FIG. shows a block diagram of an apparatus that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure.

[0065] Figure 7 FIG. shows a block diagram of a communication manager that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure.

[0066] Figure 8 FIG. shows a diagram of a system that includes an apparatus that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure.

[0067] Figure 9And Figure 10 FIG. shows a block diagram of a device supporting techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure.

[0068] Figure 11 FIG. shows a block diagram of a communication manager supporting techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure.

[0069] Figure 12 FIG. shows a diagram of a system including a device supporting techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure.

[0070] Figures 13 to 20 FIG. shows a flowchart of a method illustrating techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0071] A user equipment (UE) in a wireless communication system may operate as a relay node for a remote UE, which conveys traffic so that the remote UE can communicate with a base station. The relay UE may provide a relay sidelink for the remote UE, and the relay UE may communicate with the base station using a cellular link. The relay UE may be within the coverage of the base station, while the remote UE may be within or outside the coverage. In some cases, the remote UE may select the relay UE. For example, the remote UE may identify that there is at least one candidate relay UE in the vicinity of the remote UE. In some cases, the relay UE may announce its presence by sending a discovery message. In some examples, the remote UE may send a relay request message. Nearby candidate relay UEs may receive the relay request message and send a relay discovery message. The remote UE may detect the candidate relay UEs based on the relay discovery message. Nearby repeaters may receive the discovery solution message and respond to establish a relay sidelink. Some wireless communication systems provide a separate discovery channel for communication discovery messages. The remote UE may monitor the dedicated discovery channel to identify candidate relay UEs. However, these dedicated channels may result in significant system overhead, and the system overhead can be reduced by removing the dedicated channels. Therefore, some systems may not provide a separate discovery channel. Although removing the dedicated discovery channel can reduce system overhead and improve radio frequency spectrum efficiency, it may also remove the common channel for the remote UE to identify candidate relay UEs.

[0072] Accordingly, the wireless communication system described herein supports enhanced techniques for sidelink relay selection and reselection. In some cases, these techniques can enable a remote UE to identify and select or reselect candidate relay UEs without using a dedicated discovery channel. For example, the wireless communication system can support the relay UE and the remote UE to send and receive discovery messages on a communication channel of the relay sidelink (such as a sidelink shared channel or a sidelink control channel). In some cases, the base station can configure resources for the relay UE and the remote UE to send and receive relay discovery announcements and relay discovery requests on the relay sidelink. Accordingly, the wireless communication system can still provide for the relay UE and the remote UE to send discovery signaling without using a dedicated discovery channel. Additionally, enhanced techniques are described for a UE to determine to operate as a relay UE and for a remote UE to select a candidate relay UE to establish a relay sidelink.

[0073] Aspects of the present disclosure are first described in the context of a wireless communication system. Aspects of the present disclosure are further illustrated by means of block diagrams, system diagrams, and flowcharts relating to techniques for selecting and reselecting a sidelink repeater, and aspects of the present disclosure are described with reference to these diagrams.

[0074] Figure 1 An example of a wireless communication system 100 is shown that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The wireless communication system 100 can 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 can be a Long Term Evolution (LTE) network, an enhanced LTE (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 can 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.

[0075] The base stations 105 can be spread throughout a geographic area to form the wireless communication system 100, and can be devices of different forms or with different capabilities. The base stations 105 and the UEs 115 can communicate wirelessly via one or more communication links 125. Each base station 105 can provide a coverage area 110, and the UEs 115 and the base stations 105 can establish one or more communication links 125 over the coverage area 110. The coverage area 110 can 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.

[0076] UE 115 can be spread throughout the coverage area 110 of the wireless communication system 100, and each UE 115 can be stationary, or mobile, or both at different times. The UE 115 can be devices of different forms or with different capabilities. In Figure 1 some example UEs 115 are shown. The UE 115 described herein is 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.

[0077] The base station 105 can communicate with the core network 130, or communicate with each other, or perform both of the above operations. For example, the base station 105 can interface with the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3, or other interfaces). The base station 105 can communicate with each other directly (e.g., directly between base stations 105) on the backhaul link 120 (e.g., via X2, Xn, or other interfaces), or communicate with each other indirectly (e.g., via the core network 130), or perform both of the above operations. In some examples, the backhaul link 120 can be or include one or more wireless links.

[0078] One or more of the base stations 105 described herein can include or can be referred to by those skilled in the art as a base station transceiver, radio base station, access point, radio transceiver, Node B, evolved Node B (eNB), next-generation Node B, or gigabit Node B (any of which can be referred to as a gNB), home Node B, home evolved Node B, or some other suitable term.

[0079] The UE 115 can include or can be referred to as a mobile device, wireless device, remote device, handheld device, or subscriber device, or some other suitable term, where "device" can also be referred to as unit, station, terminal, or client, among other examples. The UE 115 can also include or can 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 can include or 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, among other examples, which can be implemented in various items such as appliances, or vehicles, meters, and other examples.

[0080] The UE 115 described herein is capable of communicating with various types of devices, such as other UEs 115 that can sometimes act as relays, as well as base stations 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.

[0081] The UE 115 and the base station 105 can communicate wirelessly with each other via one or more communication links 125 on one or more carriers. The term "carrier" can refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier for the communication link 125 can include a portion of a radio frequency spectrum band (e.g., a bandwidth part (BWP)) 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 can carry acquisition signaling (e.g., synchronization signals, system information), control signaling for coordinating the operation of the carrier, user data, or other signaling. The wireless communication system 100 can support communication with the UE 115 using carrier aggregation or multi-carrier operation. According to a carrier aggregation configuration, the UE 115 can be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation can be used with both frequency division duplex (FDD) component carriers and time division duplex (TDD) component carriers.

[0082] In some examples (e.g., in a carrier aggregation configuration), a carrier can also have acquisition signaling or control signaling for coordinating the operation of other carriers. A carrier can be associated with a frequency channel (e.g., an evolved universal mobile telecommunications system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN)) and can be placed according to a channel grid for discovery by the UE 115. A carrier can operate in an independent mode, where the UE 115 performs initial acquisition and connection via the carrier, or a carrier can operate in a non-independent mode, where a different carrier (e.g., of the same or a different radio access technology) is used to anchor the connection.

[0083] The communication link 125 shown in the wireless communication system 100 can 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 can carry downlink or uplink communication (e.g., in FDD mode) or can be configured to carry both downlink and uplink communication (e.g., in TDD mode).

[0084] A carrier can be associated with a specific bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth can be referred to as the "system bandwidth" of the carrier or the wireless communication system 100. For example, the carrier bandwidth can be one of a number of defined bandwidths for a carrier of a specific 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) can have a hardware configuration that supports communication on a specific carrier bandwidth or can be configurable to support communication on one of a set of carrier bandwidths. In some examples, the wireless communication system 100 can 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 can be configured to operate on a portion (e.g., a subband, a BWP) or all of the carrier bandwidth.

[0085] The signal waveform transmitted on a carrier can 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 OFDM (DFT-S-OFDM)). In a system employing an MCM technique, a resource element can 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 related. The number of bits carried by each resource element can depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Therefore, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate can be for the UE 115. Wireless communication resources can refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers can further increase the data rate or data integrity for communication with the UE 115.

[0086] One or more numerologies can be supported for a carrier, where a numerology can include a subcarrier spacing (Δf) and a cyclic prefix. A carrier can be divided into one or more BWPs having the same or different numerologies. In some examples, the UE115 can be configured with multiple BWPs. In some examples, a single BWP for a carrier can be active at a given time, and communication for the UE 115 can be restricted to one or more active BWPs.

[0087] It can be in a basic time unit, which can for example refer to a sampling period of T s = 1 / (Δf max ·N f ) seconds, where, Δf maxmay represent the maximum supported subcarrier spacing, and N f The time intervals for the base station 105 or the UE 115 may be represented as multiples of f which may represent the maximum supported discrete Fourier transform (DFT) size). The time intervals of the communication resources may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., in the range from 0 to 1023).

[0088] Each frame may include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a number of symbol periods (e.g., which depends on the length of the cyclic prefix added in front of each symbol period). In some wireless communication systems 100, a time slot may be further divided into a plurality of mini-slots each containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N f ones) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or the operating frequency band.

[0089] A subframe, time slot, mini-slot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in the form of a burst of shortened TTIs (sTTIs)).

[0090] Physical channels can be multiplexed on a carrier according to various techniques. For example, one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or 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 the number of symbol periods and can extend across the system bandwidth of the carrier or a subset of the system bandwidth. 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 at 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.

[0091] Each base station 105 can provide communication coverage via one or more cells (e.g., macro cells, small cells, hot spots, or other types of cells, or any combination thereof). The term "cell" can refer to a logical communication entity for communicating (e.g., on a carrier) with the base station 105 and can be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), or other identifier) 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 (such as the capabilities of the base station 105), the scope of 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 the geographic coverage areas 110, and other examples.

[0092] Macro cells typically cover a relatively large geographical area (e.g., with a radius of several kilometers) and can allow unrestricted access by UEs 115 having a service subscription with the network provider that supports the macro cell. Compared to macro cells, small cells can be associated with lower power base stations 105, and small cells can operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells can provide unrestricted access to UEs 115 having a service subscription with the 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 residence 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.

[0093] In some examples, a carrier can support multiple cells and can be configured with different cell configurations according to different protocol types that can provide access for different types of devices (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)).

[0094] In some examples, base station 105 can be movable and thus provide 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. Wireless communication system 100 can include, for example, a heterogeneous network where different types of base stations 105 use the same or different radio access technologies to provide coverage for respective geographical coverage areas 110.

[0095] Wireless communication system 100 can support synchronous or asynchronous operation. For synchronous operation, base stations 105 can have similar frame timings, and transmissions from different base stations 105 can be approximately aligned in time. For asynchronous operation, base stations 105 can have different frame timings, and in some examples, transmissions from different base stations 105 can not be aligned in time. The techniques described herein can be used for synchronous or asynchronous operation.

[0096] Some UEs 115 (e.g., MTC or IoT devices) can be low-cost or low-complexity devices and can provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC can refer to data communication technologies that allow devices to communicate with each other or with the base station 105 without human intervention. In some examples, M2M communication or MTC can include communication from devices integrated with sensors or meters to measure or capture information and relay such information to a central server or application, which utilizes the information or presents the information to a human interacting with the application. Some UEs 115 can be designed to collect information or implement automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, device monitoring, healthcare monitoring, wildlife monitoring, climate and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business billing.

[0097] Some UEs 115 can be configured to operate in power-saving modes, e.g., half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception rather than simultaneous transmission and reception). In some examples, half-duplex communication can be performed at a reduced peak rate. Other power-saving techniques for UEs 115 include entering a power-saving deep sleep mode when not participating in active communication, when operating on a limited bandwidth (e.g., according to narrowband communication), or a combination of these techniques. For example, some UEs 115 can be configured for operation using a narrowband protocol type associated with a defined portion or extent (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of the carrier, or external to the carrier.

[0098] The wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, the wireless communication system 100 can be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. The UE115 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 such as mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData). Support for mission-critical functions can include prioritization of 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.

[0099] In some examples, the UE 115 is capable of communicating directly with other UEs 115 over a D2D communication link 135 (e.g., using a peer-to-peer (P2P) or device-to-device (D2D) protocol). One or more UEs 115 utilizing D2D communication may be within the geographical coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographical coverage area 110 of the base station 105 or otherwise unable to receive transmissions from the base station 105. In some examples, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, where each UE 115 transmits to each other UE 115 in the group. In some examples, the base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving the base station 105.

[0100] In some systems, the D2D communication link 135 may be an example of a communication channel (such as a sidelink communication channel) between vehicles (e.g., the UE 115). In some examples, vehicles may communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination of these. Vehicles may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information related to the V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure (such as a roadside unit), or communicate with a network via one or more network nodes (e.g., the base station 105) using vehicle-to-network (V2N) communication, or perform both operations.

[0101] 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), 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 to or interconnects with an external network (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 mobility, authentication, and bearer management for a UE 115 served by a base station 105 associated with the core network 130. User IP packets may be transmitted through the user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to a network operator IP service 150. The operator IP service 150 may include access to the Internet, an intranet, an IP multimedia subsystem (IMS), or packet switched streaming services.

[0102] Some network devices in the wireless communication system 100 (e.g., the base station 105) may include subcomponents such as an access network entity 140, which may be an example of an access node controller (ANC). Each access network entity 140 may communicate with a UE 115 through one or more other access network transmission entities 145 (which may be referred to as radio heads, intelligent radio heads, or transmit / receive points (TRPs)). 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 the base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., the base station 105).

[0103] 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 known as the ultra-high frequency (UHF) region or the decimeter band because the wavelength range is approximately from one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, but the waves may be sufficient to penetrate structures to serve a UE 115 located indoors in a macro cell. Compared to transmissions using smaller frequencies and longer waves in 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).

[0104] 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 (also referred to as the centimeter band) or in the extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) (also referred to as the millimeter band). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communication between the UE 115 and the base station 105, and the EHF antennas of the corresponding devices may be even smaller and more closely spaced compared to UHF antennas. In some examples, this may facilitate the use of antenna arrays within the device. However, the propagation of EHF transmissions may suffer even greater atmospheric attenuation and shorter distances compared to SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency regions, and the designation of the frequency bands across these frequency regions may vary according to the country or regulatory body.

[0105] The wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may employ licensed-assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed frequency band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in an unlicensed radio frequency spectrum band, devices such as the base station 105 and the UE 115 may employ carrier sensing for collision detection and avoidance. In some examples, the operation in the unlicensed frequency band may be based on a carrier aggregation configuration that combines component carriers operating in a licensed frequency band (e.g., LAA). The operation in the unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer (P2P) transmissions, or device-to-device (D2D) transmissions, among other examples.

[0106] The base station 105 or the UE 115 may be equipped with multiple antennas, which may 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 may be located within one or more antenna arrays or antenna panels, which may support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, the antennas or antenna arrays associated with the base station 105 may be located at different geographical locations. The base station 105 may have an antenna array having a number of rows and columns of antenna ports that the base station 105 may use to support beamforming for communication with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted via the antenna ports.

[0107] Base station 105 or UE 115 can use MIMO communication to take advantage of multipath signal propagation and improve spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such a technique may be referred to as spatial multiplexing. For example, a transmitting device may transmit multiple signals via different antennas or different combinations of antennas. Similarly, a receiving device may receive multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) (where multiple spatial layers are transmitted to the same receiving device) and multi-user MIMO (MU-MIMO) (where multiple spatial layers are transmitted to multiple devices).

[0108] 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 form or direct 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 some signals propagating in a particular orientation relative to the antenna array experience constructive interference while other signals experience destructive interference. The adjustment of the signals transmitted via the antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to the signals carried via the antenna elements associated with the device. The adjustment associated with each antenna element of the antenna elements may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0109] As part of the beamforming operation, base station 105 or UE 115 can use beam scanning techniques. For example, base station 105 can use multiple antennas or an antenna array (e.g., an antenna panel) to perform beamforming operations for directional communication with UE 115. 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, 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 (e.g., by the transmitting device such as base station 105 or by the receiving device such as UE 115) to identify the beam direction for subsequent transmissions or receptions performed by base station 105.

[0110] The base station 105 may transmit some signals (e.g., data signals associated with a particular receiving device (e.g., UE 115)) in a single beam direction (e.g., the direction associated with a particular receiving device). In some examples, the beam direction associated with transmission along a single beam direction may be determined based on signals transmitted in one or more beam directions. For example, UE 115 may receive one or more of the signals transmitted by base station 105 in different directions and may report to base station 105 an indication of the signal with the highest signal quality or otherwise acceptable signal quality received by UE 115.

[0111] In some examples, multiple beam directions may be used to perform transmissions by a device (e.g., by 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 signals (CRS), channel state information reference signals (CSI-RS)) that may or may not be 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., for identifying beam directions for subsequent transmissions or receptions by UE 115) or to transmit signals in a single direction (e.g., for transmitting data to a receiving device).

[0112] When receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from base station 105, a receiving device (e.g., UE 115) may attempt multiple receiving configurations (e.g., directional listening). For example, the receiving device may receive by receiving via different antenna sub-arrays, by processing received signals according to different antenna sub-arrays, by receiving according to different sets of receive beamforming weights (e.g., different sets of directional listening weights) applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array (any of the above operations may be referred to as "listening" according to different receiving configurations or receiving directions), thereby attempting multiple 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, the highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening according to multiple beam directions).

[0113] Wireless communication system 100 may be a packet-based network operating according to a hierarchical protocol stack. In the user plane, communication at the bearer or packet data convergence protocol (PDCP) layer may be IP-based. The radio link control (RLC) layer may perform packet segmentation and reassembly for transmission over logical channels. The media access control (MAC) layer may perform priority handling and multiplexing of logical channels to transport channels. The MAC layer may 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 may provide the establishment, configuration, and maintenance of an RRC connection (which supports radio bearers for user plane data) between UE 115 and base station 105 or core network 130. At the physical layer, transport channels may be mapped to physical channels.

[0114] UE 115 and base station 105 may support retransmission of data to increase the likelihood that the data is successfully received. Hybrid Automatic Repeat reQuest (HARQ) feedback is a technique for increasing the likelihood that data is correctly received over communication link 125. HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), Forward Error Correction (FEC), and retransmission (e.g., Automatic Repeat reQuest (ARQ)). HARQ may improve throughput at the MAC layer under poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device may support same-slot HARQ feedback, where the device may provide HARQ feedback for data received in previous symbols in a particular slot during that slot. In other cases, the device may provide HARQ feedback in a subsequent slot or according to some other time interval.

[0115] UE 115 may operate as a relay UE 115 and provide a relay side link for a remote UE 115. The remote UE 115 may send data to the relay UE 115 over the relay side link, and the relay UE 115 may send the data of the remote UE 115 to the base station 105 over the cellular link. The relay UE 115 may be within the coverage of the base station 105, and the remote UE 115 may be within or outside the coverage. The remote UE 115 may identify that there is at least one relay UE 115 in the vicinity of the remote UE 115 to request relay services. In some cases, the relay UE 115 may announce its presence by sending a discovery message. For example, the relay UE 115 may periodically send a discovery message. The remote UE 115 may receive the relay announcement and establish communication with the relay UE 115. In some examples, the remote UE 115 may announce a discovery solicitation message. Nearby candidate relay UE 115s may receive the discovery solution message and respond to establish a relay side link.

[0116] UE 115 may first meet a set of criteria to become a relay UE 115. For example, the relay UE 115 may be authorized by the network for relay services. In some cases, the relay UE 115 may indicate to the MME its ability to support relay communication. The relay UE 115 may notify the upper layer that the relay UE 115 is configured with radio resources that may be used for relay-related side link communication transmissions. In some cases, the Reference Signal Received Power (RSRP) measurement performed by the relay UE on the primary cell may meet a pair of configured RSRP thresholds. For example, for a UE 115 operating as a relay UE 115, the RSRP of the primary cell may be higher than the low RSRP threshold and lower than the high RSRP threshold. In some cases, the high RSRP threshold may be configured to limit the interference level caused by side link transmissions.

[0117] The base station 105 may provide transmission and reception resources, minimum and maximum thresholds for the cellular link quality observed by the D2D relay UE, a maximum threshold for the cellular link quality observed by the remote UE before transmitting a relay discovery solicitation message, and a threshold for the D2D link quality at which the remote UE 115 triggers relay reselection.

[0118] Once the remote UE 115 detects a relay UE candidate, the remote UE 115 may select from the candidates based on the sidelink radio quality and the provided connectivity services. For example, the remote UE 115 may select a relay UE from the relay UE candidates based on whether the RSRP measurement of the relay UE candidate is higher than a configured RSRP threshold. The remote UE 115 may also select the relay UE 115 based on which candidates can provide connectivity services for the remote UE 115.

[0119] Some wireless communication systems provide a separate discovery channel for communication discovery messages. For example, when the UE 115 determines to operate as a relay UE 115 in these systems, the relay UE 115 may send a relay announcement on a dedicated periodic discovery channel. The remote UE 115 may monitor the dedicated periodic discovery channel to identify candidate relay UEs 115. However, some wireless communication systems (such as the wireless communication system 100) may not provide a separate discovery channel. While removing the dedicated discovery channel can reduce system overhead and improve radio frequency spectrum efficiency, it may also remove the common channel for the remote UE 115 to identify the relay UE 115. Therefore, the wireless communication system 100 may support enhanced techniques for sidelink relay selection and reselection. In some cases, these techniques may enable the remote UE 115 to identify and select or reselect candidate relay UEs 115 without using a dedicated discovery channel.

[0120] The wireless communication system 115 may support sending discovery messages on the communication channel of the relay sidelink. For example, the relay UE 115 may send a relay discovery announcement on the communication channel of the relay sidelink (such as the physical sidelink shared channel (PSSCH) or the physical sidelink control channel (PSCCH)). For example, the relay discovery announcement may be sent (e.g., broadcast) using the PC5 interface on the relay sidelink. In some cases, the base station 105 may configure resources on the relay sidelink for the relay UE115 and the remote UE 115 to send and receive relay discovery announcements and relay discovery requests. Therefore, the wireless communication system 100 can still provide for the relay UE 115 and the remote UE 115 to send discovery signaling without using a dedicated discovery channel.

[0121] Figure 2FIG. 200 shows an example of a wireless communication system that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. In some examples, wireless communication system 200 may implement aspects of wireless communication system 100. Wireless communication system 200 includes relay UE 210, remote UE 215-a, and remote UE 215-b, each of which may be an example of UE 115 described with reference to Figure 1 Wireless communication system 200 may include base station 205, which may be an example of base station 105 described with reference to Figure 1 Base station 205 may include aspects of a proximity service (ProSe) function or be connected to a ProSe function.

[0122] Relay UE 210 may provide a relay sidelink 220 for remote UE 215. Remote UE 215 may send data to relay UE 210 on the relay sidelink, and relay UE 210 may send the data of remote UE 215 to base station 205 on cellular link 225. For example, remote UE 215-a may send data to and receive data from relay UE 210 on relay sidelink 220-a, and remote UE 215-b may send data to and receive data from relay UE 210 on relay sidelink 220-b.

[0123] Relay UE 210 may be within the coverage of base station 205. The remote UE may be within the coverage (similar to remote UE 215-b) or outside the coverage (similar to remote UE 215-c). In some cases, relay communication may be provided for remote UE 215 within the coverage area to provide service continuity (e.g., during a mobility event or handover or to enhance a weak connection).

[0124] In some cases, wireless communication system 200 may support techniques for single-hop relay communication, where remote UE 215 is connected to base station 205 via a single-hop to an additional UE 115 (e.g., relay UE 115). In some cases, wireless communication system 200 may also support techniques for multi-hop relay communication, where remote UE 215 is connected to base station 205 via multiple relay UEs.

[0125] The remote UE 215 can identify that there is at least one relay UE 210 in the vicinity of the remote UE 215 to request relay services. During relay discovery, the remote UE 215 can obtain the UE identifier of the relay UE 210 for sidelink transmission and reception of relay services. In some cases, the relay UE 210 can announce its presence by sending a discovery message. For example, the relay UE 210 can periodically send discovery messages for relay-initiated discovery or Model A discovery procedures. The remote UE 215 can receive the relay announcement and establish communication with the relay UE 210. In some examples, the remote UE can announce a discovery solicitation message. Nearby repeaters can receive the discovery solution message and respond to establish a relay sidelink. This can be an example of remote-initiated discovery or Model B discovery procedures.

[0126] Some wireless communication systems provide a separate discovery channel for communicating discovery messages. For example, when the UE 115 determines to operate as the relay UE 210 in these systems, the relay UE 115 can send a relay announcement on a dedicated periodic discovery channel. The remote UE 215 can monitor the dedicated periodic discovery channel to identify candidate relay UEs. However, some wireless communication systems (such as the wireless communication system 200) may not provide a separate discovery channel. Although removing the dedicated discovery channel can reduce system overhead and improve radio frequency spectrum efficiency, it may also remove the common channel for the remote UE 215 to identify the relay UE 210. Therefore, the wireless communication system 200 can support enhanced techniques for sidelink relay selection and reselection. In some cases, these techniques can enable the remote UE 215 to identify and select or reselect candidate relay UEs 115 without using a dedicated discovery channel.

[0127] The wireless communication system 200 can support sending discovery messages on the communication channel of the relay sidelink 220. For example, the relay UE 210 can send a relay discovery announcement on the communication channel of the relay sidelink 220 (such as the sidelink shared channel). For example, the relay discovery announcement can be sent (e.g., broadcast) using the PC5 interface on the relay sidelink 220. In some cases, the base station 205 can configure resources on the relay sidelink 220 for the relay UE 210 and the remote UE 215 to send and receive relay discovery announcements and relay discovery requests. Therefore, the wireless communication system 200 can still provide for the relay UE 210 and the remote UE 215 to send discovery signaling without using a dedicated discovery channel.

[0128] The wireless communication system 200 also supports the UE 115 to determine enhanced conditions for operating as a relay UE 210. For example, the relay UE 210 can determine to operate as a repeater and send a relay announcement based on checking the conditions at the relay UE 210. In some examples, this can be referred to as UE autonomous relay operation, which may not be network-configured. If the relay UE 210 is in the RRC connected mode and is configured with a transmission resource pool for sending relay announcements.

[0129] The relay UE 210 described herein can determine to operate as a repeater based on multiple sets of thresholds. For example, the relay UE 210 can be configured with two sets of RSRP thresholds. When the relay UE 210 is not connected to the remote UE 215, the first set of thresholds can be used, and when the relay UE 210 is connected to at least one remote UE 215, the second set of thresholds can be used. Each set of RSRP thresholds can include a high RSRP threshold and a low RSRP threshold, and if the RSRP of the primary cell is between the high RSRP threshold and the low RSRP threshold, the relay UE 210 can determine to operate as a repeater. Compared with the first set of thresholds, the thresholds in the second set of thresholds can be slightly relaxed to increase the possibility of service continuity of the relay node. For example, when the relay UE 210 is connected to the remote UE 215, there can be a larger acceptable RSRP measurement range, so that the relay UE 210 is less likely to abandon the relay service of the connected remote UE.

[0130] In some cases, the network may configure the relay UE 210 to start transmitting relay information. For example, the relay UE 210 may report radio resource management (RRM) measurements of the cellular link 225 to the base station 205. The RRM measurements may include, for example, the RSRP measurement of the primary cell provided by the base station 205. In some cases, the relay UE 210 may report the QoS that the relay UE 210 can support for sidelink communication. In some examples, the relay UE 210 may indicate load information. In some cases, the load information may be based on the load of the sidelink communication provided by the relay UE 210. The load information may include the channel busy rate. The load information may be reported in the measurement report together with the RRM measurements. In some examples, the relay UE 210 may report battery information or power information. For example, the relay UE 210 may indicate its current battery level, power consumption information, or both. In some cases, the battery and power information may be reported in the measurement report together with the RRM measurements. The base station 205 may receive the reported UE operating conditions and determine whether the relay UE 210 should provide relay services for the remote UE 215. If the relay UE 210 is suitable for providing relay, the base station 205 may instruct the relay UE 210 to transmit relay information, such as discovery announcements, on the relay sidelink 220.

[0131] In some examples, the base station 205 may configure the relay UE 210 to operate as a repeater for a set of QoS. For example, as part of the relay configuration, the base station 205 may limit which QoS the relay UE 210 can act as a repeater for and perform discovery. The relay UE 210 may indicate the QoS it supports for the remote UE 215. In some cases, the relay UE 210 may indicate the supported QoS through the application code of the discovery message. For example, the application code may incorporate an indication of the supported (e.g., maximum) QoS level of the relay UE 210. In some cases, the supported QoS may be indicated to the relay UE 210 via a MAC CE.

[0132] The wireless communication system 200 may support enhanced techniques for a remote UE 215 to select or reselect a suitable repeater. The remote UE 215 may detect suitable relay UE candidates based on a set of criteria. For example, suitable relay UEs may be configured by the network with a resource pool or preconfigured with a resource pool. In some cases, a suitable relay UE may provide a sidelink with good radio quality. For example, the RSRP measurement of the relay sidelink may be greater than a configured RSRP threshold. In some cases, a suitable relay UE may provide a QoS level for the relay sidelink 220 that can meet the QoS requirements of the services of the remote UE 215. In some cases, a suitable relay UE may have a load below a load threshold. In some cases, a suitable relay UE may have a battery (e.g., and power) above a battery threshold. In some cases, the base station 205 may broadcast the load and battery thresholds in the system information block, or the remote UE 215 may be preconfigured with the load and battery thresholds.

[0133] The remote UE 215 may identify suitable relay UE candidates that meet the described criteria. In some cases, a candidate relay UE may be suitable based on meeting one or more of the above criteria, or a candidate relay UE may be suitable based on meeting all of the criteria. In some cases, the remote UE 215 may select a suitable candidate relay UE with the highest sidelink radio link quality. Additionally or alternatively, the remote UE 215 may consider other criteria for selecting the relay UE 210.

[0134] The wireless communication system 200 may support enhanced techniques for the remote UE 215 to reselect the relay UE 210. When the signal strength of the current repeater is below a configured signal strength threshold, repeater selection may be triggered. The remote UE 215 may receive a layer 2 (L2) link release message (e.g., an upper layer message) from the relay UE 210. In some cases, the relay link may be discarded based on the relay's inability to support the QoS requirements of the service. Then, the remote UE 215 may reselect a suitable relay UE based on the RSRP of the candidate relay UE, the candidate relay UE meeting the QoS requirements, the candidate relay UE having a load below the load threshold, and the candidate relay UE having a battery and power above the battery threshold. The remote UE 215 may reselect to a suitable relay node with the highest sidelink radio quality.

[0135] The remote UE 215 can measure the RSRP of the relay sidelink 220 from the relay UE 210, and the remote UE 215 can use this RSRP for relay selection or reselection. In some cases, the remote UE 215 can measure the sidelink discovery RSRP. In some cases, the remote UE 215 can apply layer 3 filtering to the relevant ProSe relay UE identifier. The filter coefficients can be indicated via an SIB (e.g., SIB19) or pre-configured. In some cases, the sidelink RSRP can be used as a layer 1 (L1) measurement, and the sidelink RSRP can be filtered based on the L3 filter coefficients.

[0136] The wireless communication system 200 can support enhanced techniques for configuring resource pool allocations for transmitting discovery signals on the relay sidelink 220. Based on transmitting discovery signaling on sidelink communication channels such as the PSSCH and PSCCH, separate transmission resource pools can be configured from the common communication channels. In some cases, the transmission resource pool for sidelink discovery may be periodic. In some cases, the resource pool can be configured via RRC. For example, the RRC configuration of the resource pool can include a one-bit indication regarding the resource pool being used for sidelink discovery. In some cases, there may be separate resource pool configurations for discovery. For example, there may be different types of RRC configurations for the resource pool used to transmit discovery messages. In some cases, there may be a one-bit indication in the downlink control information regarding the resource being used for relay discovery instead of normal sidelink operation. For example, the base station 205 can send downlink control information to schedule sidelink resources for the relay UE 210. The downlink control information can include an indicator regarding the scheduled resource being used for discovery instead of normal sidelink operation.

[0137] Figure 3 An example of a process flow 300 is shown that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure. In some examples, the process flow 300 can implement aspects of the wireless communication system 100. The process flow 300 can include a base station 305, a UE 310, and a UE 315. The base station 305 can be an example of the base station 105 or 205 as described with reference to Figure 1 and Figure 2 described. In some cases, the base station �05 can be connected to the ProSe function via the core network, for example. The UE310 and UE 315 can each be an example of the UE 115 as described with reference to Figure 1 and Figure 2 described. In some cases, the UE 310 can provide a relay sidelink for the UE 315, or the UE 310 can be a relay candidate for providing a relay sidelink for the UE 310.

[0138] UE 310 may be attached to a wireless communication network including base station 305. UE 310 may be authorized and configured for UE-to-network relay operation. In some cases, the MME of the core network may assist in attaching UE 310 and authorize UE 310 as a relay UE. At 320, UE 310 and base station 305 may establish an RRC connection. UE 310 may send sidelink UE information to base station 305. In some cases, UE 310 may receive an RRC reconfiguration message from base station 305, and in response, UE 310 may send an RRC reconfiguration complete message. In some cases, UE 310 may be configured with parameters for relay communication via an RRC message or during RRC connection establishment.

[0139] At 325, UE 310 may determine to operate as a relay UE based on a set of thresholds configured for UE 310. For example, UE 310 may receive an RRC message (e.g., at 320) from base station 305 that indicates a plurality of sets of thresholds including at least the set of thresholds. In some cases, the plurality of sets of thresholds may include two sets of thresholds. The first set of thresholds may be used when UE 310 does not have any attached remote UEs, and the second set of thresholds may be used when UE 320 has at least one attached remote UE.

[0140] At 330, UE 310 may send a discovery announcement request to the ProSe function, which includes the quality of service level supported by UE 310 for relay communication. In some cases, the discovery announcement request may include an application ID that indicates that the request is for UE 310 to act as a repeater. In some cases, the discovery announcement request may be sent to the ProSe function via base station 305. At 335, UE 310 may receive a relay discovery announcement response to the relay discovery announcement request. The relay discovery announcement response may include an application code based on the request for UE 310 to act as a repeater. At 340, UE 310 and base station 305 may determine a destination L2 ID and an application code for reception.

[0141] In some cases, UE 310 may be configured with a set of resources for sending a relay discovery announcement. For example, UE 310 may be configured with a set of periodic resources on a sidelink communication channel that are configured for relay discovery. In some cases, a resource pool for discovery may be configured via RRC. In some cases, the RRC-configured discovery resource pool may be used for dynamic as well as type 1 and type 2 configured authorized communication. In some cases, downlink control information may schedule sidelink resources, and an indicator in the downlink control information may indicate that the scheduled sidelink resources are for transmitting discovery messages.

[0142] At 345, the UE 310 may send a relay discovery announcement on the sidelink channel based at least in part on a determination to operate as a relay UE, which indicates support for relay communication. The relay discovery announcement may be sent on a sidelink communication channel (such as the PSSCH or PSCCH). In some cases, the relay announcement may be broadcast via the PC5 interface. In some cases, an indication message for relay discovery may be included at the Packet Data Convergence Protocol (PDCP) layer. The UE 315 may distinguish whether a received message is a discovery message based on the indication in the PDCP. In some cases, the relay discovery announcement may include an indicator of the QoS level supported by the UE 310, the load of the UE 310, the battery level of the UE 310, or a combination thereof.

[0143] The UE 315 may monitor the relay discovery announcement on the sidelink channel to establish relay communication with the relay UE. The UE 315 may receive the relay discovery announcement via broadcast on the sidelink channel. In some cases, the relay discovery announcement may indicate that the UE 310 supports at least the QoS level of the traffic of the UE 315. In some cases, the UE 315 may identify a candidate relay UE based on the broadcast relay discovery announcement. The UE 315 may identify a suitable candidate UE based on the following: the suitable candidate UE is configured with a resource pool, the sidelink radio quality towards the candidate is higher than a threshold, the supported QoS meets the QoS requirements of the sidelink traffic, the load of the candidate UE is lower than a load threshold, the battery of the candidate UE is higher than a battery threshold, or any combination thereof.

[0144] The UE 315 may determine that the UE 310 meets the criteria for being a suitable relay UE candidate. The UE 315 may determine that the UE 310 has the highest sidelink radio quality among the candidate relay UEs, and the UE 315 may select the UE 310 to act as a relay UE at 350. In some cases, the UE 315 may measure the sidelink discovery RSRP of the sidelink to the UE 310. The UE 315 may apply L3 filtering to the UE 310 to determine the RSRP measurement for the UE 310.

[0145] At 355, UE 315 and UE 310 may establish relay sidelink communication. For example, UE 315 may send a direct communication request to UE 310, and in response, UE 310 may send a direct security mode command. UE 315 may send a direct security mode complete to UE 310, and in response, receive a direct communication acceptance to establish direct (e.g., D2D) relay sidelink communication between UE 310 and UE 315. At 360, UE 315 may communicate with base station 305 via UE 310 acting as a relay UE.

[0146] Figure 4 An example of a process flow 400 that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure is shown. In some examples, process flow 400 may implement aspects of wireless communication system 100. Process flow 400 may include base station 405, UE 410, and UE 415. Base station 405 may be an example of base station 105 or 205 as described with reference to Figure 1 and Figure 2 In some cases, base station 405 may be connected to a ProSe function via a core network, for example. UE 410 and UE 415 may each be an example of UE 115 as described with reference to Figure 1 and Figure 2 In some cases, UE 410 may provide a relay sidelink for UE 415, or UE 410 may be a relay candidate for providing a relay sidelink for UE 415.

[0147] UE 410 may attach to a wireless communication network that includes base station 405. UE 410 may be authorized and configured for UE-to-network relay operation. In some cases, the MME of the core network may assist in attaching UE 410 and authorizing UE 410. At 420, UE 410 and base station 405 may establish an RRC connection. UE 410 may send sidelink UE information to base station 405. In some cases, UE 410 may receive an RRC reconfiguration message from base station 405, and in response, UE 410 may send an RRC reconfiguration complete message. In some cases, UE 410 may be configured with parameters for relay communication via an RRC message or during RRC connection establishment.

[0148] UE 415 can determine a relay connection to the base station 405 via a relay UE. At 425, UE 415 can send a discovery announcement request to the ProSe function, which includes the quality of service level required by UE 410 for relay communication. In some cases, the discovery announcement request can include an application ID, which indicates that the request is for connecting UE 415 to the relay UE. In some cases, the discovery announcement request can be sent to the ProSe function via the base station 405. At 430, UE 415 can receive a relay discovery announcement response to the relay discovery announcement request. The relay discovery announcement response can include an application code based on the request for connecting UE 415 to the relay UE. At 435, the base station 405 can identify a sidelink configuration for UEs (e.g., including UE 410) near UE 415, and determine a destination L2 ID and application code for reception.

[0149] At 440, UE 415 can send a relay request on the sidelink channel. In some cases, the relay request can be broadcast via the PC5 interface. In some cases, the relay request can be sent on a sidelink communication channel (such as the PSSCH or PSCCH). In some cases, an indication message can be included at the PDCP layer for indicating relay discovery. UE 410 can distinguish whether the received message is a discovery message based on the indication in the PDCP.

[0150] In some cases, UE 415 can be configured with a set of resources for sending the relay request. For example, UE 415 can be configured with a periodic set of resources on the sidelink communication channel, which is configured for relay discovery. In some cases, the resource pool for discovery can be indicated via RRC configuration or via SIB. In some examples, UE 415 can be pre-configured with a set of resources for sending the relay request on the communication sidelink channel. In some cases, the RRC-configured discovery resource pool can be used for dynamic and type 1 and type 2 configured authorized communication. In some cases, the downlink control information can schedule the sidelink resources, and an indicator in the downlink control information can indicate that the scheduled sidelink resources are for transmitting discovery messages.

[0151] At 445, UE 410 can determine to operate as a relay UE based on receiving the relay request and a set of thresholds configured for UE 410. For example, UE 410 can receive an RRC message (e.g., at 420) from the base station 405 indicating multiple sets of thresholds. In some cases, the relay request can indicate the requested QoS level, and UE 410 can determine to operate as a relay UE based on being able to support the requested QoS level.

[0152] At 450, the UE 410 may send a relay discovery announcement on the sidelink channel based on a determination to operate as a relay UE, which indicates support for relay communication. In some cases, the relay discovery announcement may be sent based on receiving a relay request. The relay discovery announcement may be sent on a sidelink communication channel such as the PSSCH or PSCCH. In some cases, the relay announcement may be broadcast via the PC5 interface. In some cases, an indication message for relay discovery may be included at the PDCP layer. The UE 415 may distinguish whether a received message is a discovery message based on the indication in the PDCP. In some cases, the UE 410 may be configured with a set of resources for sending the relay discovery announcement.

[0153] The UE 415 may monitor the relay discovery announcement on the sidelink channel to establish relay communication with the relay UE. The UE 415 may receive the relay discovery announcement via broadcast on the sidelink channel. In some cases, the relay discovery announcement may indicate that the UE 410 supports at least the QoS level of the services of the UE 415. In some cases, the UE 415 may identify candidate relay UEs based on the broadcast relay discovery announcement. The UE 415 may identify a suitable candidate UE based on: the suitable candidate UE is configured with a resource pool, the sidelink radio quality towards the candidate is higher than a threshold, the supported QoS meets the QoS requirements of the sidelink service, the load of the candidate UE is lower than a load threshold, the battery of the candidate UE is higher than a battery threshold, or any combination thereof.

[0154] The UE 415 may determine that the UE 410 meets the criteria for being a suitable candidate relay UE. The UE 415 may determine that the UE 410 has the highest sidelink radio quality among the candidate relay UEs, and the UE 415 may select the UE 410 to act as a relay UE at 455. In some cases, the UE 415 may measure the sidelink discovery RSRP of the sidelink to the UE 410. The UE 415 may apply L3 filtering to the UE 410 to determine the RSRP measurement for the UE 410.

[0155] At 460, the UE 415 and the UE 410 may establish relay sidelink communication. For example, the UE 415 may send a direct communication request to the UE 410, and in response, the UE 410 may send a direct security mode command. The UE 415 may send a direct security mode complete to the UE 410, and in response, receive a direct communication acceptance to establish direct (e.g., D2D) relay sidelink communication between the UE 410 and the UE 415. At 465, the UE 415 may communicate with the base station 405 via the UE 410 acting as a relay UE.

[0156] Figure 5 FIG. 500 is a block diagram of a device 505 that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure. The device 505 may be an example of aspects of a UE 115 as described herein. The device 505 may include a receiver 510, a communication manager 515, and a transmitter 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).

[0157] The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to techniques for selecting and reselecting sidelink repeaters, etc.). The information may be passed to other components of the device 505. The receiver 510 may be an example of aspects of the transceiver 820 described with reference to Figure 8 FIG. The receiver 510 may utilize a single antenna or a set of antennas.

[0158] The communication manager 515 may perform operations including: determining to operate as a relay UE based on a set of thresholds configured for a first UE; sending, on a sidelink channel, a relay discovery announcement indicating support for relay communication based on the determination to operate as a relay UE; and establishing relay communication with a second UE based on the sending of the relay discovery announcement on the sidelink channel. The communication manager 515 may also perform operations including: monitoring relay discovery announcements on the sidelink channel to establish relay communication with a first UE operating as a relay UE, where the relay communication is associated with a quality of service level; receiving, via broadcast on the sidelink channel, a relay discovery announcement from the first UE, where the first UE supports a quality of service level for relay communication; and establishing relay communication with the first UE based on receiving the relay discovery announcement. The communication manager 515 may be an example of aspects of the communication manager 810 described herein.

[0159] The communication manager 515 or its sub-components may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 515 or its sub-components may be executed by a general-purpose processor, a DSP, an application specific integrated circuit (ASIC), an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

[0160] The communication manager 515 or its sub-components may be physically located at various locations, including being distributed such that some of the functions are implemented by one or more physical components at different physical locations. In some examples, in accordance with various aspects of the present disclosure, the communication manager 515 or its sub-components may be separate and distinct components. In some examples, in accordance with various aspects of the present disclosure, the communication manager 515 or its sub-components may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in the present disclosure, or combinations thereof.

[0161] The transmitter 520 may send signals generated by other components of the device 505. In some examples, the transmitter 520 may be co-located with the receiver 510 in a transceiver module. For example, the transmitter 520 may be an example of aspects of the transceiver 820 described with reference to Figure 8 The transmitter 520 may utilize a single antenna or a set of antennas.

[0162] Figure 6 Block diagram 600 of a device 605 is shown that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The device 605 may be an example of aspects of the device 505 or the UE 115 described herein. The device 605 may include a receiver 610, a communication manager 615, and a transmitter 645. The device 605 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0163] The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to techniques for selecting and reselecting a sidelink repeater, etc.). The information may be passed to other components of the device 605. The receiver 610 may be an example of aspects of the transceiver 820 described with reference to Figure 8 The receiver 610 may utilize a single antenna or a set of antennas.

[0164] The communication manager 615 may be an example of aspects of the communication manager 515 described herein. The communication manager 615 may include a relay operation determination component 620, a discovery announcement sending component 625, a relay communication establishment component 630, a discovery announcement monitoring component 635, and a discovery announcement receiving component 640. The communication manager 615 may be an example of aspects of the communication manager 810 described herein.

[0165] The relay operation determination component 620 may determine to operate as a relay UE based on a set of thresholds configured for the first UE. The discovery announcement sending component 625 may send, on a sidelink channel, a relay discovery announcement indicating support for relay communication based on the determination to operate as a relay UE. The relay communication establishment component 630 may establish relay communication with a second UE based on the sending of the relay discovery announcement on the sidelink channel.

[0166] The discovery announcement monitoring component 635 may monitor relay discovery announcements on a sidelink channel to establish relay communication with the first UE operating as a relay UE, where the relay communication is associated with a quality of service level. The discovery announcement receiving component 640 may receive, via broadcast on the sidelink channel, a relay discovery announcement from the first UE, where the first UE supports the quality of service level for relay communication. The relay communication establishment component 630 may establish relay communication with the first UE based on receiving the relay discovery announcement.

[0167] The transmitter 645 may send signals generated by other components of the device 605. In some examples, the transmitter 645 may be co-located with the receiver 610 in a transceiver module. For example, the transmitter 645 may be an example of aspects of the transceiver 820 described with reference to Figure 8 The transmitter 645 may utilize a single antenna or a set of antennas.

[0168] Figure 7 FIG. 700 is a block diagram illustrating a communication manager 705 that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The communication manager 705 may be an example of aspects of the communication manager 515, communication manager 615, or communication manager 810 described herein. The communication manager 705 may include a relay operation determination component 710, a discovery announcement sending component 715, a relay communication establishment component 720, a relay request receiving component 725, a relay operation condition reporting component 730, a relay discovery resource component 735, a relay communication measurement component 740, a discovery announcement monitoring component 745, a discovery announcement receiving component 750, a relay request sending component 755, and a relay selection component 760. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0169] The relay operation determination component 710 may determine to operate as a relay UE based on a set of thresholds configured for the first UE. In some examples, the relay operation determination component 710 may receive a radio resource control message from a base station, the radio resource control message indicating a set of multiple sets of thresholds including the set of thresholds. In some examples, the relay operation determination component 710 may receive a set of quality of service levels from the base station, wherein the relay discovery announcement is sent on a sidelink channel based on the set of quality of service levels including a quality of service level for relay communication.

[0170] In some examples, the relay operation determination component 710 may receive a radio resource control configuration of a set of resources for sending a relay discovery announcement on a sidelink channel from the base station. In some examples, the relay operation determination component 710 may send a relay discovery announcement request to the base station, the relay discovery announcement request including a quality of service level supported by the first UE for relay communication. In some examples, the relay operation determination component 710 may receive a relay discovery announcement response to the relay discovery announcement request from the base station, wherein the sending of the relay discovery announcement is based on receiving the relay discovery announcement response.

[0171] In some cases, the set of multiple sets of thresholds includes a first set of thresholds used when the first UE is not connected to a remote UE and a second set of thresholds used when the first UE is connected to at least one remote UE. In some cases, the difference between the high threshold and the low threshold in the first set of thresholds is less than the difference between the high threshold and the low threshold in the second set of thresholds. In some cases, the determination of operating as a relay UE is also based on the mobility state of the first UE.

[0172] The discovery announcement sending component 715 may send a relay discovery announcement indicating support for relay communication on a sidelink channel based on the determination of operating as a relay UE. In some examples, the discovery announcement sending component 715 may indicate to a second UE a quality of service level supported by the first UE for relay communication based on the sending of the relay discovery announcement. In some examples, the discovery announcement sending component 715 may include an indicator associated with the relay discovery in the PDCP packet of the relay discovery announcement. In some cases, the quality of service level is indicated by a media access control element or by an application code associated with the discovery announcement message.

[0173] The relay communication establishment component 720 may establish relay communication with a second UE based on the sending of the relay discovery announcement on a sidelink channel. In some examples, the relay communication establishment component 720 may establish relay communication with the first UE based on receiving the relay discovery announcement.

[0174] It is found that the discovery announcement monitoring component 745 can monitor relay discovery announcements on the sidelink channel to establish relay communication with a first UE operating as a relay UE, where the relay communication is associated with a quality of service level. The discovery announcement receiving component 750 can receive a relay discovery announcement from the first UE via broadcast on the sidelink channel, where the first UE supports the quality of service level for the relay communication. In some examples, the discovery announcement receiving component 750 can identify an indicator in the PDCP packet of the relay discovery announcement that is associated with the relay discovery for the relay discovery announcement.

[0175] The relay request receiving component 725 can receive a relay request on the sidelink channel from a second UE for operating as a relay UE for the second UE, where the determination of operating as a relay UE is based on the received relay request. In some examples, the relay request receiving component 725 can indicate load information for the first UE, battery information for the first UE, the quality of service level supported for the relay communication, or a combination thereof to the second UE, where the relay request is received based on the indication. The relay operation condition reporting component 730 can report reference signal measurements, load information for the first UE, battery information for the first UE, or any combination thereof to the base station. In some examples, the relay operation condition reporting component 730 can receive an indication for sending a relay discovery announcement from the base station based on the report. In some cases, the load information includes the channel busy rate for the sidelink channel for the first UE. In some cases, the reference signal measurements, load information, battery information, or any combination thereof are sent in a measurement report for radio resource management.

[0176] The relay discovery resource component 735 can receive downlink control information from the base station, and the downlink control information schedules a resource set for the first UE to send a relay discovery announcement on the sidelink channel. The relay communication measurement component 740 can receive a measurement report of the sidelink channel from the second UE on the sidelink channel based on L3 filtering of the reference signal measurement. In some examples, the relay communication measurement component 740 can measure the reference signal received from the first UE. In some examples, the relay communication measurement component 740 can filter the reference signal based on the identifier of the first UE. In some examples, the relay communication measurement component 740 can send a measurement report for the reference signal to the first UE based on the filtering.

[0177] The relay request sending component 755 may determine to establish relay communication with a base station. In some examples, the relay request sending component 755 may send a relay discovery announcement request including a quality of service level for the relay communication. In some examples, the relay request sending component 755 may receive a relay discovery announcement response based on sending the relay discovery announcement request. In some examples, the relay request sending component 755 may send a relay request for the first UE to operate as a relay UE on a sidelink channel based on the relay discovery announcement response, where the relay discovery announcement is received based on sending the relay request.

[0178] The relay selection component 760 may receive an indication that the first UE supports a quality of service level for relay communication. In some examples, the relay selection component 760 may select the first UE as a relay UE for relay communication. In some examples, the relay selection component 760 may receive an indication that the first UE supports a quality of service level for relay communication, where the selection is based on the indication. In some examples, the relay selection component 760 may receive an indication of the load of the first UE, where the first UE is selected based on the load of the first UE being lower than a load threshold.

[0179] In some examples, the relay selection component 760 may receive a system information block including a load threshold. In some examples, the relay selection component 760 may receive an indication of the battery level of the first UE, where the first UE is selected based on the battery level being higher than a battery threshold. In some examples, the relay selection component 760 may receive a system information block including a battery threshold. In some examples, the relay selection component 760 may determine that a third UE cannot support a quality of service level for relay communication, where the relay communication is established with the first UE based on the determination. In some cases, the indication is received via a media access control element or through application code associated with a relay discovery message. In some cases, the relay communication is established with the first UE based on: the first UE providing a quality of service level for relay communication, the load of the first UE meeting the load threshold, the battery level of the first UE meeting the battery threshold, or a combination thereof.

[0180] Figure 8FIG. shows a system 800 including a device 805 that supports techniques for selecting and reselecting a sidelink repeater, in accordance with aspects of the present disclosure. The device 805 may be an example of the device 505, the device 605, or the UE 115 described herein, or may include components of the device 505, the device 605, or the UE 115. The device 805 may include components for two-way voice and data communication, including components for sending and receiving communications, including a communication manager 810, an I / O controller 815, a transceiver 820, an antenna 825, a memory 830, and a processor 840. These components may communicate electronically via one or more buses (e.g., bus 845).

[0181] The communication manager 810 may perform the following operations: determine to operate as a relay UE based on a set of thresholds configured for a first UE; send a relay discovery announcement indicating support for relay communication on a sidelink channel based on the determination to operate as a relay UE; and establish relay communication with a second UE based on the sending of the relay discovery announcement on the sidelink channel. The communication manager 810 may also perform the following operations: monitor relay discovery announcements on the sidelink channel to establish relay communication with a first UE operating as a relay UE, where the relay communication is associated with a quality of service level; receive a relay discovery announcement from the first UE via broadcast on the sidelink channel, where the first UE supports the quality of service level for relay communication; and establish relay communication with the first UE based on receiving the relay discovery announcement.

[0182] The I / O controller 815 may manage input and output signals for the device 805. The I / O controller 815 may also manage peripheral devices not integrated into the device 805. In some cases, the I / O controller 815 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 815 may utilize an operating system such as MS- MS- OS / or another known operating system. In other cases, the I / O controller 815 may represent a modem, a keyboard, a RAT label, a touch screen, or a similar device or interact with the above devices. In some cases, the I / O controller 815 may be implemented as part of a processor. In some cases, a user may interact with the device 805 via the I / O controller 815 or via hardware components controlled by the I / O controller 815.

[0183] The transceiver 820 can communicate bidirectionally via one or more antennas, wired or wireless links as described above. For example, the transceiver 820 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 820 can also include a modem for modulating packets and providing the modulated packets to the antenna for transmission, and demodulating packets received from the antenna.

[0184] In some cases, the wireless device can include a single antenna 825. However, in some cases, the device can have more than one antenna 825 capable of simultaneously transmitting or receiving multiple wireless transmissions.

[0185] The memory 830 can include RAM and ROM. The memory 830 can store computer-readable, computer-executable code 835 that includes instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, in addition, the memory 830 can also contain a BIOS that can control basic hardware or software operations, such as interactions with peripheral components or devices.

[0186] The processor 840 can include intelligent hardware devices (e.g., general-purpose processors, DSPs, 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 can be configured to operate a memory array using a memory controller. In other cases, the memory controller can be integrated into the processor 840. The processor 840 can be configured to execute computer-readable instructions stored in a memory (e.g., memory 830) to cause the device 805 to perform various functions (e.g., functions or tasks supporting techniques for selecting and reselecting sidelink repeaters).

[0187] The code 835 can include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communication. The code 835 can be stored in a non-transitory computer-readable medium (e.g., system memory or other types of memory). In some cases, the code 835 may not be directly executable by the processor 840, but can cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0188] Figure 9FIG. 900 is a block diagram of an apparatus 905 supporting techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The apparatus 905 may be an example of aspects of a base station 105 as described herein. The apparatus 905 may include a receiver 910, a communication manager 915, and a transmitter 920. The apparatus 905 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0189] The receiver 910 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to techniques for selecting and reselecting a sidelink repeater, etc.). The information may be passed to other components of the apparatus 905. The receiver 910 may be an example of aspects of the transceiver 1220 described in Figure 12 reference. The receiver 910 may utilize a single antenna or a set of antennas.

[0190] The communication manager 915 may perform operations including: receiving a relay discovery request message including a quality of service level for relay communication between a first UE and a second UE; sending a relay discovery response message including an application code for relay discovery based on the quality of service level for the relay communication; configuring a first UE with a resource set for relay discovery advertisement on a sidelink channel; and receiving data for a second UE from the first UE based on the relay communication between the first UE and the second UE. The communication manager 915 may be an example of aspects of the communication manager 1210 described herein.

[0191] The communication manager 915 or its subcomponents may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 915 or its subcomponents may be executed by a general-purpose processor, a DSP, an application specific integrated circuit (ASIC), an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

[0192] The communication manager 915 or its sub-components may be physically located at various locations, including being distributed such that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, in accordance with aspects of the present disclosure, the communication manager 915 or its sub-components may be separate and distinct components. In some examples, in accordance with aspects of the present disclosure, the communication manager 915 or its sub-components may be combined with one or more other hardware components, including but not limited to input / output (I / O) components, transceivers, network servers, another computing device, one or more other components described in the present disclosure, or combinations thereof.

[0193] The transmitter 920 may transmit signals generated by other components of the device 905. In some examples, the transmitter 920 may be co-located with the receiver 910 in a transceiver module. For example, the transmitter 920 may be an example of aspects of the transceiver 1220 described with reference to Figure 12 The transmitter 910 may utilize a single antenna or a set of antennas.

[0194] Figure 10 FIG. 1000 is a block diagram illustrating a device 1005 that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The device 1005 may be an example of aspects of the device 905 or the base station 105 described herein. The device 1005 may include a receiver 1010, a communication manager 1015, and a transmitter 1040. The device 1005 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0195] The receiver 1010 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to techniques for selecting and reselecting a sidelink repeater, etc.). The information may be passed to other components of the device 1005. The receiver 1010 may be an example of aspects of the transceiver 1220 described with reference to Figure 12 The receiver 1010 may utilize a single antenna or a set of antennas.

[0196] The communication manager 1015 may be an example of aspects of the communication manager 915 described herein. The communication manager 1015 may include a discovery request message component 1020, a discovery response message component 1025, a relay resource configuration component 1030, and a relay data reception component 1035. The communication manager 1015 may be an example of aspects of the communication manager 1210 described herein.

[0197] The discovery request message component 1020 may receive a relay discovery request message that includes a quality of service level for relay communication between a first UE and a second UE. The discovery response message component 1025 may send a relay discovery response message that includes application code for relay discovery based on the quality of service level for the relay communication. The relay resource configuration component 1030 may configure the first UE with a set of resources for relay discovery announcements on a sidelink channel on the sidelink channel.

[0198] The relay data receiving component 1035 may receive data for the second UE from the first UE based on relay communication between the first UE and the second UE.

[0199] The transmitter 1040 may send signals generated by other components of the device 1005. In some examples, the transmitter 1040 may be co-located with the receiver 1010 in a transceiver module. For example, the transmitter 1040 may be an example of aspects of the transceiver 1220 described with reference to Figure 12 The transmitter 1040 may utilize a single antenna or a group of antennas.

[0200] Figure 11 Block diagram 1100 shows a communication manager 1105 that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The communication manager 1105 may be an example of aspects of the communication manager 915, the communication manager 1015, or the communication manager 1210 described herein. The communication manager 1105 may include a discovery request message component 1110, a discovery response message component 1115, a relay resource configuration component 1120, a relay data receiving component 1125, a relay operating condition configuration component 1130, and a relay condition report receiving component 1135. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0201] The discovery request message component 1110 may receive a relay discovery request message that includes a quality of service level for relay communication between a first UE and a second UE. The discovery response message component 1115 may send a relay discovery response message that includes application code for relay discovery based on the quality of service level for the relay communication. In some examples, the discovery response message component 1115 may indicate the quality of service level for the relay communication based on the application code for relay discovery. In some cases, the relay discovery request message is received from the first UE and the relay discovery response message is sent to the first UE. In some cases, the relay discovery request message is received from the second UE and the relay discovery response message is sent to the second UE.

[0202] The relay resource configuration component 1120 may configure a first UE with a set of resources for relay discovery announcements on a sidelink channel. In some examples, the relay resource configuration component 1120 may send an indication via downlink control information that the set of resources is configured for discovery signaling. In some examples, the relay resource configuration component 1120 may send an indication via radio resource control signaling that the set of resources is configured for discovery signaling.

[0203] The relay data receiving component 1125 may receive data for a second UE from the first UE based on relay communication between the first UE and the second UE. The relay operation condition configuration component 1130 may send a radio resource control message to the first UE indicating a set of several threshold sets. In some examples, the relay operation condition configuration component 1130 may configure the first UE with a set of quality of service levels, where the first UE is configured to perform discovery for relay communication based on the set of quality of service levels including the quality of service level of the relay communication. In some cases, the set of several threshold sets includes a first threshold set used when the first UE is not connected to a remote UE and a second threshold set used when the first UE is connected to at least one remote UE. In some cases, the difference between the high threshold and the low threshold in the first threshold set is less than the difference between the high threshold and the low threshold in the second threshold set.

[0204] The relay condition report receiving component 1135 may receive reference signal measurements, load information for the first UE, battery information for the first UE, or any combination thereof from the first UE. In some examples, the relay condition report receiving component 1135 may send an indication to broadcast a relay discovery announcement for the first UE based on the report. In some cases, the load information includes the channel busy rate for the sidelink channel for the first UE. In some cases, the reference signal measurements, load information, or battery information, or any combination thereof, are received in a measurement report for radio resource management.

[0205] Figure 12 FIG. shows a system 1200 including a device 1205 that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The device 1205 may be an example of a device 905, a device 1005, or a base station 105 as described herein or include components of the device 905, the device 1005, or the base station 105. The device 1205 may include components for two-way voice and data communication, including components for sending and receiving communication, including a communication manager 1210, a network communication manager 1215, a transceiver 1220, an antenna 1225, a memory 1230, a processor 1240, and an inter-station communication manager 1245. These components may communicate electronically via one or more buses (e.g., bus 1250).

[0206] The communication manager 1210 may perform the following operations: receive a relay discovery request message including a quality of service level for relay communication between a first UE and a second UE; send a relay discovery response message including an application code for relay discovery based on the quality of service level for the relay communication; configure the first UE with a resource set for relay discovery advertisement on a sidelink channel; and receive data for the second UE from the first UE based on the relay communication between the first UE and the second UE.

[0207] The network communication manager 1215 may manage communication with the core network (e.g., via one or more wired backhaul links). For example, the network communication manager 1215 may manage the transmission of data communication for client devices (e.g., one or more UEs 115).

[0208] The transceiver 1220 may communicate bidirectionally via one or more antennas, wired or wireless links as described above. For example, the transceiver 1220 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 1220 may also include a modem for modulating packets and providing the modulated packets to the antenna for transmission, and demodulating packets received from the antenna.

[0209] In some cases, the wireless device may include a single antenna 1225. However, in some cases, the device may have more than one antenna 1225, which are capable of simultaneously transmitting or receiving multiple wireless transmissions.

[0210] The memory 1230 may include RAM, ROM, or a combination thereof. The memory 1230 may store computer-readable code 1235, which includes instructions that, when executed by a processor (e.g., processor 1240), cause the device to perform the various functions described herein. In some cases, in addition, the memory 1230 may further contain a BIOS, which may control basic hardware or software operations, such as interactions with peripheral components or devices.

[0211] The processor 1240 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, 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 1240 may be configured to operate a memory array using a memory controller. In some cases, the memory controller may be integrated into the processor 1240. The processor 1240 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1230) to cause the device 1205 to perform various functions (e.g., functions or tasks supporting techniques for selecting and reselecting sidelink repeaters).

[0212] The inter-station communication manager 1245 may manage communication with other base stations 105 and may include a controller or scheduler for collaboratively controlling communication with the UE 115 with other base stations 105. For example, the inter-station communication manager 1245 may coordinate the scheduling of transmissions to the UE 115 to implement various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-station communication manager 1245 may provide an X2 interface within the LTE / LTE-A wireless communication network technology to provide communication between the base stations 105.

[0213] The code 1235 may include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communication. The code 1235 may be stored in a non-transitory computer-readable medium (e.g., system memory or other types of memory). In some cases, the code 1235 may not be directly executable by the processor 1240, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0214] Figure 13 A flowchart illustrating a method 1300 for supporting techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure is shown. Operations of the method 1300 may be implemented by the UE 115 or its components as described herein. For example, operations of the method 1300 may be performed by a communication manager as described with reference to Figures 5 to 8 described. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0215] At 1305, the UE may determine to operate as a relay UE based on a set of thresholds configured for the first UE. The operation of 1305 may be performed according to the methods described herein. In some examples, aspects of the operation of 1305 may be performed by a relay operation determination component as described with reference to Figures 5 to 8 described.

[0216] At 1310, the UE may send, on the sidelink channel, a relay discovery announcement indicating support for relay communication based on a determination to operate as a relay UE. The operation of 1310 may be performed according to the methods described herein. In some examples, aspects of the operation of 1310 may be performed by a discovery announcement sending component as described with reference to Figures 5 to 8 the discovery announcement sending component described.

[0217] At 1315, the UE may establish relay communication with a second UE based on the sending of the relay discovery announcement on the sidelink channel. The operation of 1315 may be performed according to the methods described herein. In some examples, aspects of the operation of 1315 may be performed by a relay communication establishment component as described with reference to Figures 5 to 8 the relay communication establishment component described.

[0218] Figure 14 FIG. 1400 is a flow diagram illustrating a method 1400 for supporting techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The operations of method 1400 may be implemented by a UE 115 or components thereof as described herein. For example, the operations of method 1400 may be performed by a communication manager as described with reference to Figures 5 to 8 the communication manager described. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0219] At 1405, the UE may receive, on the sidelink channel, a relay request for operating as a relay UE for a second UE, wherein the determination to operate as a relay UE is based on receiving the relay request. The operation of 1405 may be performed according to the methods described herein. In some examples, aspects of the operation of 1405 may be performed by a relay request receiving component as described with reference to Figures 5 to 8 the relay request receiving component described.

[0220] At 1410, the UE may determine to operate as a relay UE based on a set of thresholds configured for the first UE. The operation of 1410 may be performed according to the methods described herein. In some examples, aspects of the operation of 1410 may be performed by a relay operation determination component as described with reference to Figures 5 to 8 the relay operation determination component described.

[0221] At 1415, the UE may send, on the sidelink channel, a relay discovery announcement indicating support for relay communication based on the determination to operate as a relay UE. The operation of 1415 may be performed according to the methods described herein. In some examples, aspects of the operation of 1415 may be performed by a discovery announcement sending component as described with reference to Figures 5 to 8 the discovery announcement sending component described.

[0222] At 1420, the UE may establish relay communication with a second UE based on sending a relay discovery announcement on the sidelink channel. The operation of 1420 may be performed according to the methods described herein. In some examples, aspects of the operation of 1420 may be performed by a relay communication establishment component as described with reference to Figures 5 to 8 the description.

[0223] Figure 15 FIG. 1500 is a flow diagram illustrating a method 1500 for supporting techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. The operations of method 1500 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1500 may be performed by a communication manager as described with reference to Figures 5 to 8 the description. In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0224] At 1505, the UE may receive a radio resource control message from a base station, the radio resource control message indicating a set of threshold sets including the set of thresholds. The operation of 1505 may be performed according to the methods described herein. In some examples, aspects of the operation of 1505 may be performed by a relay operation determination component as described with reference to Figures 5 to 8 the description.

[0225] At 1510, the UE may determine to operate as a relay UE based on the set of thresholds configured for the first UE. The operation of 1510 may be performed according to the methods described herein. In some examples, aspects of the operation of 1510 may be performed by a relay operation determination component as described with reference to Figures 5 to 8 the description.

[0226] At 1515, the UE may send a relay discovery announcement on the sidelink channel indicating support for relay communication based on the determination to operate as a relay UE. The operation of 1515 may be performed according to the methods described herein. In some examples, aspects of the operation of 1515 may be performed by a discovery announcement sending component as described with reference to Figures 5 to 8 the description.

[0227] At 1520, the UE may establish relay communication with a second UE based on the sending of the relay discovery announcement on the sidelink channel. The operation of 1520 may be performed according to the methods described herein. In some examples, aspects of the operation of 1520 may be performed by a relay communication establishment component as described with reference to Figures 5 to 8 the description.

[0228] Figure 16 FIG. 1600 is a flow chart illustrating a method 1600 that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure. Operations of method 1600 may be implemented by a UE 115 or components thereof as described herein. For example, operations of method 1600 may be performed by a communication manager as described with reference to Figures 5 to 8 described. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0229] At 1605, the UE may monitor a relay discovery announcement on a sidelink channel to establish relay communication with a first UE operating as a relay UE, where the relay communication is associated with a quality of service level. The operation at 1605 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1605 may be performed by a discovery announcement monitoring component as described with reference to Figures 5 to 8 described.

[0230] At 1610, the UE may receive, via broadcast on the sidelink channel, a relay discovery announcement from the first UE, where the first UE supports a quality of service level for the relay communication. The operation at 1610 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1610 may be performed by a discovery announcement receiving component as described with reference to Figures 5 to 8 described.

[0231] At 1615, the UE may establish relay communication with the first UE based on receiving the relay discovery announcement. The operation at 1615 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1615 may be performed by a relay communication establishment component as described with reference to Figures 5 to 8 described.

[0232] Figure 17 FIG. 1700 is a flow chart illustrating a method 1700 that supports techniques for selecting and reselecting sidelink repeaters in accordance with aspects of the present disclosure. Operations of method 1700 may be implemented by a UE 115 or components thereof as described herein. For example, operations of method 1700 may be performed by a communication manager as described with reference to Figures 5 to 8 described. In some examples, the UE may execute an instruction set to control functional units of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0233] At 1705, the UE may determine to establish relay communication with a base station. The operation at 1705 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1705 may be performed by a component as described with reference toFigures 5 to 8 The described relay request sending component is to execute.

[0234] At 1710, the UE may send a relay discovery announcement request including a quality of service level for relay communication. The operation of 1710 may be performed according to the methods described herein. In some examples, aspects of the operation of 1710 may be performed by a relay request sending component as described with reference to Figures 5 to 8 The described relay request sending component is to execute.

[0235] At 1715, the UE may receive a relay discovery announcement response based on sending the relay discovery announcement request. The operation of 1715 may be performed according to the methods described herein. In some examples, aspects of the operation of 1715 may be performed by a relay request sending component as described with reference to Figures 5 to 8 The described relay request sending component is to execute.

[0236] At 1720, the UE may send a relay request for the first UE to operate as a relay UE on a sidelink channel based on the relay discovery announcement response, wherein the relay discovery announcement is received based on sending the relay request. The operation of 1720 may be performed according to the methods described herein. In some examples, aspects of the operation of 1720 may be performed by a relay request sending component as described with reference to Figures 5 to 8 The described relay request sending component is to execute.

[0237] At 1725, the UE may monitor the relay discovery announcement on the sidelink channel to establish relay communication with the first UE operating as a relay UE, wherein the relay communication is associated with a quality of service level. The operation of 1725 may be performed according to the methods described herein. In some examples, aspects of the operation of 1725 may be performed by a discovery announcement monitoring component as described with reference to Figures 5 to 8 The described discovery announcement monitoring component is to execute.

[0238] At 1730, the UE may receive a relay discovery announcement via broadcast on the sidelink channel from the first UE, wherein the first UE supports a quality of service level for relay communication. The operation of 1730 may be performed according to the methods described herein. In some examples, aspects of the operation of 1730 may be performed by a discovery announcement receiving component as described with reference to Figures 5 to 8 The described discovery announcement receiving component is to execute.

[0239] At 1735, the UE may establish relay communication with the first UE based on receiving the relay discovery announcement. The operation of 1735 may be performed according to the methods described herein. In some examples, aspects of the operation of 1735 may be performed by a relay communication establishment component as described with reference to Figures 5 to 8 The described relay communication establishment component is to execute.

[0240] Figure 18FIG. 1800 is a flow chart illustrating a method 1800 that describes techniques for supporting the selection and reselection of a sidelink repeater in accordance with aspects of the present disclosure. Operations of method 1800 may be implemented by a UE 115 or components thereof as described herein. For example, the operations of method 1800 may be performed by a communication manager as described with reference to Figures 5 to 8 In some examples, the UE may execute an instruction set to control functional units of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

[0241] At 1805, the UE may receive an indication that a first UE supports a quality of service level for relay communication, wherein the selection is based on the indication. The operation of 1805 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1805 may be performed by a relay selection component as described with reference to Figures 5 to 8 described.

[0242] At 1810, the UE may select the first UE as a relay UE for relay communication. The operation of 1810 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1810 may be performed by a relay selection component as described with reference to Figures 5 to 8 described.

[0243] At 1815, the UE may monitor relay discovery announcements on the sidelink channel to establish relay communication with the first UE operating as a relay UE, wherein the relay communication is associated with the quality of service level. The operation of 1815 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1815 may be performed by a discovery announcement monitoring component as described with reference to Figures 5 to 8 described.

[0244] At 1820, the UE may receive, via broadcast on the sidelink channel, a relay discovery announcement from the first UE, wherein the first UE supports a quality of service level for relay communication. The operation of 1820 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1820 may be performed by a discovery announcement receiving component as described with reference to Figures 5 to 8 described.

[0245] At 1825, the UE may establish relay communication with the first UE based on receiving the relay discovery announcement. The operation of 1825 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1825 may be performed by a relay communication establishment component as described with reference to Figures 5 to 8 described.

[0246] Figure 19FIG. 1900 is a flow chart illustrating a method 1900 that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. Operations of method 1900 may be implemented by a base station 105 or components thereof as described herein. For example, operations of method 1900 may be performed by a communication manager as described with reference to Figures 9 to 12 described. In some examples, the base station may execute an instruction set to control functional units of the base station to perform the functions described below. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functions described below.

[0247] At 1905, the base station may receive a relay discovery request message that includes a quality of service level for relay communication between a first UE and a second UE. The operation at 1905 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1905 may be performed by a discovery request message component as described with reference to Figures 9 to 12 described.

[0248] At 1910, the base station may send a relay discovery response message that includes an application code for relay discovery based on the quality of service level for the relay communication. The operation at 1910 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1910 may be performed by a discovery response message component as described with reference to Figures 9 to 12 described.

[0249] At 1915, the base station may configure a first UE with a resource set for relay discovery advertisement on a sidelink channel. The operation at 1915 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1915 may be performed by a relay resource configuration component as described with reference to Figures 9 to 12 described.

[0250] At 1920, the base station may receive data for a second UE from the first UE based on the relay communication between the first UE and the second UE. The operation at 1920 may be performed in accordance with methods described herein. In some examples, aspects of the operation at 1920 may be performed by a relay data reception component as described with reference to Figures 9 to 12 described.

[0251] Figure 20 FIG. 2000 is a flow chart illustrating a method 2000 that supports techniques for selecting and reselecting a sidelink repeater in accordance with aspects of the present disclosure. Operations of method 2000 may be implemented by a base station 105 or components thereof as described herein. For example, operations of method 2000 may be performed by a communication manager as described with reference to Figures 9 to 12performed by the described communication manager. In some examples, the base station may execute an instruction set to control the functional units of the base station to perform the functions described below. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functions described below.

[0252] At 2005, the base station may configure a first UE with a set of quality of service levels, where the first UE is configured to perform discovery for relay communication based on the set of quality of service levels including the quality of service level for relay communication. The operation of 2005 may be performed according to the methods described herein. In some examples, aspects of the operation of 2005 may be performed by a relay operation condition configuration component as described with reference to Figures 9 to 12 description.

[0253] At 2010, the base station may receive a relay discovery request message including a quality of service level for relay communication between a first UE and a second UE. The operation of 2010 may be performed according to the methods described herein. In some examples, aspects of the operation of 2010 may be performed by a discovery request message component as described with reference to Figures 9 to 12 description.

[0254] At 2015, the base station may send a relay discovery response message including application code for relay discovery based on the quality of service level for relay communication. The operation of 2015 may be performed according to the methods described herein. In some examples, aspects of the operation of 2015 may be performed by a discovery response message component as described with reference to Figures 9 to 12 description.

[0255] At 2020, the base station may configure the first UE on a sidelink channel with a set of resources for relay discovery announcements on the sidelink channel. The operation of 2020 may be performed according to the methods described herein. In some examples, aspects of the operation of 2020 may be performed by a relay resource configuration component as described with reference to Figures 9 to 12 description.

[0256] At 2025, the base station may receive data for the second UE from the first UE based on relay communication between the first UE and the second UE. The operation of 2025 may be performed according to the methods described herein. In some examples, aspects of the operation of the 2025 may be performed by a relay data reception component as described with reference to Figures 9 to 12 description.

[0257] It should be noted that the methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise modified, and other implementations are possible. Additionally, aspects from two or more methods may be combined.

[0258] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for purposes of illustration and the LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein apply beyond the scope of LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may apply 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.

[0259] The information and signals described herein can be represented using any of a variety of different technologies and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0260] Various illustrative blocks and components described in connection with the disclosure herein can be implemented or performed using a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. The processor can also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0261] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of the present disclosure and the 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 of these items. The features implementing the functions can also be physically located at various positions, including being distributed such that portions of the functions are implemented at different physical locations.

[0262] A computer-readable medium includes both a non-transitory computer storage medium and a communication medium, where the communication medium includes any medium that facilitates transfer of a computer program from one place to another. The non-transitory storage medium can be any available medium that can be accessed by a general purpose computer or a special purpose computer. By way of example and not limitation, the non-transitory computer-readable medium can include random access memory (RAM), read only memory (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 is properly termed a computer-readable medium. For 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 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 reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable medium.

[0263] As used herein (including in the claims), the "or" as used in a list of items (e.g., a list of items 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, for example, at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Additionally, as used herein, the phrase "based on" should not be construed as a reference to a closed set of conditions. For example, an example step described as "based on condition A" can be based on both 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".

[0264] In the figures, similar components or features may have the same reference numeral. Additionally, various components of the same type can be distinguished by following the reference numeral with a dash and a second numeral, which is used to distinguish among similar components. If only the first reference numeral is used in the specification, the description applies to any one of the similar components having the same first reference numeral, regardless of the second numeral or any other subsequent numerals.

[0265] The description of example configurations is set forth in this text in conjunction with the illustrations described herein, and does not represent all examples that can be implemented or are within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration", rather than "preferred" or "advantageous over other examples". For the purpose of providing an understanding of the described technology, the detailed description includes specific details. However, the technologies may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0266] The description herein is provided to enable a person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but is accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a first user equipment (UE), comprising: Determining to operate as a relay UE at least in part based on a set of thresholds configured for the first UE, wherein the set of thresholds includes a pair of reference signal received power (RSRP) thresholds and is indicated by a radio resource control message from a base station; Receiving, from the base station, a relay configuration including a quality of service level for relay communication; Transmitting, on a sidelink channel, a relay discovery announcement indicating support for relay communication at least in part based on the determination to operate as the relay UE, wherein the relay discovery announcement is transmitted on the sidelink channel at least in part based on the quality of service level for the relay communication included in the relay configuration; and Establishing the relay communication with a second UE at least in part based on the transmission of the relay discovery announcement on the sidelink channel.

2. The method according to claim 1, further comprising: Receiving, on the sidelink channel, from the second UE a relay request to operate as the relay UE for the second UE, wherein the determination to operate as the relay UE is at least in part based on receiving the relay request.

3. The method according to claim 2, further comprising: Indicating to the second UE load information for the first UE, battery information for the first UE, the quality of service level supported for the relay communication, or a combination thereof, wherein the relay request is received at least in part based on the indication.

4. The method according to claim 1, wherein Determining to operate as a relay UE includes determining that the first UE meets the pair of RSRP thresholds.

5. The method according to claim 1, wherein, The radio resource control message indicates a plurality of sets of thresholds including the set of thresholds, and wherein the plurality of sets of thresholds includes a first set of thresholds used when the first UE is not connected to a remote UE and a second set of thresholds used when the first UE is connected to at least one remote UE.

6. The method according to claim 5, wherein The difference between the high threshold and the low threshold in the first set of thresholds is less than the difference between the high threshold and the low threshold in the second set of thresholds.

7. The method according to claim 1, wherein, The determination to operate as the relay UE is also at least in part based on the mobility state of the first UE.

8. The method according to claim 1, further comprising: Reporting to the base station reference signal measurements, load information for the first UE, battery information for the first UE, or any combination thereof; And Receiving, from the base station, an indication to transmit the relay discovery announcement at least in part based on the report.

9. The method according to claim 8, wherein The load information includes a channel busy rate for the sidelink channel for the first UE.

10. The method according to claim 8, wherein, The reference signal measurements, the load information, the battery information, or any combination thereof are transmitted in a measurement report for radio resource management.

11. The method according to claim 1, further comprising: Indicating to the second UE, at least in part based on the sending of the relay discovery announcement, a quality of service level supported by the first UE for the relay communication, wherein the quality of service level is indicated by a media access control element or by an application code associated with the discovery announcement message.

12. The method according to claim 1, further comprising: Receiving a set of quality of service levels from a base station, wherein the relay discovery announcement is sent on the sidelink channel at least in part based on the set of quality of service levels including the quality of service level for the relay communication included in the relay configuration.

13. The method according to claim 1, further comprising: Receiving a radio resource control configuration of a set of resources for sending the relay discovery announcement on the sidelink channel from a base station.

14. The method according to claim 1, further comprising: Receiving downlink control information from a base station, the downlink control information scheduling for the first UE a set of resources for sending the relay discovery announcement on the sidelink channel.

15. The method according to claim 1, further comprising: Sending a relay discovery announcement request to a base station, the relay discovery announcement request including the quality of service level supported by the first UE for the relay communication; And Receiving a relay discovery announcement response to the relay discovery announcement request from the base station, wherein the sending of the relay discovery announcement is at least in part based on receiving the relay discovery announcement response.

16. The method according to claim 1, further comprising: Including in a packet data convergence protocol (PDCP) packet of the relay discovery announcement an indicator associated with the relay discovery for the relay discovery announcement.

17. The method according to claim 1, further comprising: Receiving a measurement report of the sidelink channel from the second UE on the sidelink channel at least in part based on L3 filtering of reference signal measurements.

18. A method for wireless communication at a second user equipment (UE), comprising: Monitoring a relay discovery announcement on a sidelink channel to establish relay communication with a first UE operating as a relay UE, wherein the relay communication is associated with a quality of service level configured by a base station for the relay communication; Receiving the relay discovery announcement from the first UE via broadcast on the sidelink channel, wherein the first UE supports the quality of service level for the relay communication, wherein the relay discovery announcement is received at least in part based on the first UE determining to operate as a relay UE and the quality of service level configured by the base station for the relay communication, and the first UE determining to operate as a relay UE is at least in part based on a set of thresholds indicated by a radio resource control message from the base station; and Establishing the relay communication with the first UE at least in part based on receiving the relay discovery announcement.

19. The method according to claim 18, further comprising: Determining to establish relay communication with the base station; Send a relay discovery announcement request including a quality of service level for the relay communication; Receive a relay discovery announcement response at least in part based on sending the relay discovery announcement request; and Send a relay request for the first UE to operate as the relay UE on the sidelink channel at least in part based on the relay discovery announcement response, wherein the relay discovery announcement is received at least in part based on sending the relay request.

20. The method according to claim 18, further comprising: Receive an indication that the first UE supports the quality of service level for the relay communication.

21. The method according to claim 20, wherein, The indication is received via a media access control element or through application code associated with the relay discovery message.

22. The method according to claim 18, further comprising: Select the first UE as the relay UE for the relay communication.

23. The method according to claim 22, further comprising: Receive an indication of the load of the first UE, wherein the first UE is selected at least in part based on the load of the first UE being below a load threshold.

24. The method according to claim 22, further comprising: Receive an indication of the battery level of the first UE, wherein the first UE is selected at least in part based on the battery level being above a battery threshold.

25. The method according to claim 18, wherein The second UE is connected to a third UE for the relay communication, and the method further comprises: Determine that the third UE cannot support the quality of service level for the relay communication, wherein the relay communication is established with the first UE at least in part based on the determination.

26. The method according to claim 25, wherein The relay communication is established with the first UE at least in part based on: the first UE providing the quality of service level for the relay communication, the load of the first UE meeting the load threshold, the battery level of the first UE meeting the battery threshold, or a combination thereof.

27. The method according to claim 18, further comprising: Measure a reference signal received from the first UE; Filter the reference signal at least in part based on an identifier of the first UE; And Send a measurement report for the reference signal to the first UE at least in part based on the filtering.

28. A method for wireless communication at a base station, comprising: Receive a relay discovery request message including a quality of service level for relay communication between a first user equipment (UE) and a second UE; Send a relay discovery response message including application code for relay discovery at least in part based on the quality of service level for the relay communication; Send a radio resource control message to the first UE, the radio resource control message indicating a set of thresholds for the first UE to determine whether to operate as a relay UE, the set of thresholds including a pair of reference signal received power (RSRP) thresholds; Configure the first UE on a sidelink channel with a set of resources for relay discovery announcements on the sidelink channel; Configure a set of quality of service levels for the first UE, where the first UE is configured to perform discovery for the relay communication at least partially based on the set of quality of service levels including the quality of service level for the relay communication; and Receive data for the second UE from the first UE at least partially based on the relay communication between the first UE and the second UE.

29. The method according to claim 28, wherein, The radio resource control message indicates a plurality of sets of thresholds, the plurality of sets of thresholds including a first set of thresholds used when the first UE is not connected to a remote UE and a second set of thresholds used when the first UE is connected to at least one remote UE.

30. The method according to claim 28, further comprising: Receive a report of reference signal measurements, load information for the first UE, battery information for the first UE, or any combination thereof from the first UE; And Send an indication to broadcast the relay discovery announcement for the first UE at least partially based on the report.

31. The method according to claim 30, wherein, The load information includes a channel busy rate for the sidelink channel for the first UE.

32. The method according to claim 30, wherein, The reference signal measurements, the load information, the battery information, or any combination thereof are received in a measurement report for radio resource management.

33. The method according to claim 28, further comprising: Indicate the quality of service level for the relay communication at least partially based on the application code for the relay discovery.

34. An apparatus for wireless communication at a first user equipment (UE), comprising: A memory; One or more processors, wherein the one or more processors are configured to cause the UE to: Determine to operate as a relay UE at least partially based on a set of thresholds configured for the first UE, wherein the set of thresholds includes a pair of reference signal received power (RSRP) thresholds and is indicated by a radio resource control message from a base station; Receive a relay configuration from the base station including a quality of service level for the relay communication; Send a relay discovery announcement indicating support for the relay communication on a sidelink channel at least partially based on the determination to operate as the relay UE, wherein the relay discovery announcement is sent on the sidelink channel at least partially based on the quality of service level for the relay communication included in the relay configuration; and Establish the relay communication with a second UE at least partially based on the sending of the relay discovery announcement on the sidelink channel.

35. The apparatus according to claim 34, wherein The one or more processors are further configured to cause the UE to: Receive a relay request on the sidelink channel from the second UE to operate as the relay UE for the second UE, wherein the determination to operate as the relay UE is at least partially based on receiving the relay request.

36. The apparatus according to claim 35, wherein, The one or more processors are further configured to cause the UE to: Indicate to the second UE load information for the first UE, battery information for the first UE, a quality of service level supported for the relay communication, or a combination thereof, wherein the relay request is received at least in part based on the indication.

37. The apparatus according to claim 34, wherein, Determining to operate as a relay UE includes determining that the first UE meets the pair of RSRP thresholds.

38. The apparatus according to claim 34, wherein, The radio resource control message indicates a plurality of threshold sets including the set of thresholds, and wherein the plurality of threshold sets includes a first threshold set used when the first UE is not connected to a remote UE and a second threshold set used when the first UE is connected to at least one remote UE.

39. The apparatus according to claim 38, wherein, The difference between the high threshold and the low threshold in the first threshold set is less than the difference between the high threshold and the low threshold in the second threshold set.

40. The apparatus according to claim 34, wherein, The determination to operate as the relay UE is also at least in part based on the mobility state of the first UE.

41. The apparatus according to claim 34, wherein, The one or more processors are further configured to cause the UE to: Report reference signal measurements, load information for the first UE, battery information for the first UE, or any combination thereof to the base station; and Receive an indication from the base station to send the relay discovery announcement at least in part based on the report.

42. The apparatus according to claim 41, wherein, The load information includes the channel busy rate for the sidelink channel for the first UE.

43. The device according to claim 41, wherein, The reference signal measurements, the load information, the battery information, or any combination thereof are sent in a measurement report for radio resource management.

44. The apparatus according to claim 34, wherein, The one or more processors are further configured to cause the UE to: Indicate to the second UE the quality of service level supported by the first UE for the relay communication at least in part based on the sending of the relay discovery announcement, wherein the quality of service level is indicated by a media access control element or by an application code associated with the discovery announcement message.

45. The apparatus according to claim 34, wherein, The one or more processors are further configured to cause the UE to: Receive a set of quality of service levels from the base station, wherein the relay discovery announcement is sent on the sidelink channel at least in part based on the set of quality of service levels including the quality of service level for the relay communication included in the relay configuration.

46. The apparatus according to claim 34, wherein, The one or more processors are further configured to cause the UE to: Receive a radio resource control configuration of a set of resources for sending the relay discovery announcement on the sidelink channel from the base station.

47. The apparatus according to claim 34, wherein The one or more processors are further configured to cause the UE to: Receive downlink control information from the base station, the downlink control information scheduling a set of resources for the first UE to send the relay discovery announcement on the sidelink channel.

48. The apparatus according to claim 34, wherein, The one or more processors are further configured to cause the UE to: Send a relay discovery announcement request to the base station, the relay discovery announcement request including the quality of service level supported by the first UE for the relay communication; and Receive a relay discovery advertisement response for the relay discovery advertisement request from the base station, wherein the transmission of the relay discovery advertisement is at least partially based on receiving the relay discovery advertisement response.

49. The device according to claim 34, wherein, The one or more processors are further configured to cause the UE to: Include an indicator in the packet data convergence protocol (PDCP) packet of the relay discovery advertisement that the relay discovery advertisement is associated with relay discovery.

50. The apparatus according to claim 34, wherein, The one or more processors are further configured to cause the UE to: Receive a measurement report of the sidelink channel from the second UE on the sidelink channel at least partially based on L3 filtering of reference signal measurements.

Images