Relay Selection in Sidelink Communication

Abstract

Disclosed are methods, apparatus, and systems for relay selection in communications. The method includes receiving, by a base station, one or more discovery messages communicated between a UE and one or more candidate relays, where the UE and the one or more candidate relays are attached to the base station; receiving, by the base station, one or more measurements related to one or more signals transmitted between the base station and the one or more candidate relays; determining, by the base station, based on at least one of the one or more discovery messages or the one or more measurements, whether the one or more candidate relays meet relay selection criteria; and selecting, by the base station and based on the determining, at least one relay from the one or more candidate relays for multipath transmission for the UE.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 482,128, filed January 30, 2023, entitled "SELECTION OF RELAY UES FOR MULTI-PATH SIDELINK RELAYING COMMUNICATION," the entire contents of which are incorporated herein by reference.

[0002] Apparatus and methods consistent with the present disclosure relate generally to communications, and more particularly to methods, systems, and devices for multipath transmission in communications. [Background technology]

[0003] A user equipment (UE) may employ multipath transmission to communicate with a base station to improve communication reliability and efficiency. The multipath transmission may include a direct path between the UE and the base station and one or more indirect paths between the UE and the base station via one or more selected relays. A relay may be one or more other UEs in communication. For an indirect path, communication between the UE and the base station includes a first link between the UE and the relay and a second link between the relay and the base station. Selecting a relay that can guarantee the communication quality of both links is important for the communication quality of the entire indirect path. However, relay selection (or reselection) is difficult because the communication characteristics of the first link between the UE and the relay are unknown to the base station, and the communication characteristics of the second link between the relay and the base station are unknown to the UE. That is, neither the UE nor the base station has global knowledge of the characteristics of both the first and second links, causing inaccuracies in relay selection and thereby degrading the quality of the indirect path. A system and method for reliable and accurate relay selection (or reselection) for multipath transmission is desired. Summary of the Invention

[0004] According to some embodiments of the present disclosure, a base station in a communication system is provided, the base station comprising: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: receive one or more discovery messages communicated between a UE and one or more candidate relays, where the UE and the one or more candidate relays are attached to the base station; receive one or more measurements on one or more signals transmitted between the base station and the one or more candidate relays; determine whether the one or more candidate relays meet a relay selection criterion based on at least one of the one or more discovery messages or the one or more measurements; and select at least one relay from the one or more candidate relays for multipath transmission for the UE.

[0005] According to some embodiments of the present disclosure, a UE for communication is provided, the UE comprising: a memory storing instructions; and a processor, the processor executing the instructions stored in the memory to receive one or more discovery messages from one or more candidate relays attached to a base station, the one or more discovery messages including at least one of (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission; transmit the one or more discovery messages to the base station; receive from the base station at least one relay selected from the one or more candidate relays; and trigger multipath transmission, the multipath transmission being a direct path between the UE and the base station. and an indirect path between the UE and the base station via the selected at least one relay.

[0006] According to some embodiments of the present disclosure, a UE for communication is provided, the UE comprising: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: send a relay selection request to a base station to be forwarded to one or more candidate relays attached to the base station; send one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receive from the base station at least one relay selected from the one or more candidate relays; and trigger multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the at least one selected relay.

[0007] According to some embodiments of the present disclosure, a relay for a UE in communication is provided, the relay comprising: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: send one or more discovery messages to the UE, the one or more discovery messages including at least one of (1) one or more link quality parameters for one or more links between the UE and the relay, (2) an attachment status parameter indicating attachment of the relay to a base station, or (3) an availability status parameter indicating availability of the relay for multipath transmission; and send one or more measurements to the base station regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating availability of the relay for multipath transmission.

[0008] According to some embodiments of the present disclosure, a relay for a UE in communication is provided, the relay comprising: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: receive a relay selection request from a base station; receive one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the relay; transmit the received one or more relay selection response messages to the base station; and transmit one or more measurements related to one or more signals transmitted between the base station and the relay to the base station, the one or more measurements including at least one of (1) one or more link quality parameters for the one or more links between the base station and the relay, or (2) one or more availability status parameters indicative of the availability of the relay for multipath transmissions.

[0009] According to some embodiments of the present disclosure, a method for selecting at least one relay for a UE in a communication system is provided. The method includes receiving, by a base station, one or more discovery messages communicated between the UE and one or more candidate relays, where the UE and the one or more candidate relays are attached to the base station; receiving, by the base station, one or more measurements related to one or more signals transmitted between the base station and the one or more candidate relays; determining, by the base station, based on at least one of the one or more discovery messages or the one or more measurements, whether the one or more candidate relays meet a relay selection criterion; and selecting, by the base station and based on the determining, at least one relay from the one or more candidate relays for multipath transmission for the UE.

[0010] According to some embodiments of the present disclosure, a method for a UE attached to a base station in a communication system is provided, the method including: receiving one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages including at least one of (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission; transmitting the one or more discovery messages to the base station; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; and triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the at least one selected relay.

[0011] According to some embodiments of the present disclosure, a method for a UE attached to a base station in a communication system is provided, the UE including: sending a relay selection request to a base station to be forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; and triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the at least one selected relay.

[0012] According to some embodiments of the present disclosure, a method for a relay for a UE in a communication system is provided, where the relay and the UE are attached to a base station. The method includes: transmitting one or more discovery messages to the UE, where the one or more discovery messages include at least one of (1) one or more link quality parameters for one or more links between the UE and the relay, (2) an attachment status parameter indicating attachment of the relay to the base station, or (3) an availability status parameter indicating availability of the relay for multipath transmission; and transmitting one or more measurements to the base station regarding one or more signals transmitted between the base station and the relay, where the one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating availability of the relay for multipath transmission.

[0013] According to some embodiments of the present disclosure, a method for a relay for a UE in a communication system is provided, where the relay and the UE are attached to a base station. The method includes receiving a relay selection request from the base station, receiving one or more relay selection response messages from the UE, where the one or more relay selection response messages include one or more link quality parameters for one or more links between the UE and the relay, transmitting the received one or more relay selection response messages to the base station, and transmitting one or more measurements related to one or more signals transmitted between the base station and the relay to the base station, where the one or more measurements include at least one of (1) one or more link quality parameters for the one or more links between the base station and the relay, or (2) one or more availability status parameters indicative of the availability of the relay for multipath transmission.

[0014] According to some embodiments of the present disclosure, one of the base stations in communication to perform the method A non-transitory computer-readable medium storing instructions executable by one or more processors is provided. The method includes receiving one or more discovery messages communicated between a UE and one or more candidate relays, where the UE and the one or more candidate relays are attached to a base station, receiving one or more measurements related to one or more signals transmitted between the base station and the one or more candidate relays, determining whether the one or more candidate relays meet a relay selection criterion based on at least one of the one or more discovery messages or the one or more measurements, and selecting at least one relay from the one or more candidate relays for multipath transmission for the UE based on the determining.

[0015] According to some embodiments of the present disclosure, a non-transitory computer-readable medium storing instructions executable by one or more processors of a UE in communication to perform a method is provided. The method includes receiving one or more discovery messages from one or more candidate relays attached to a base station, the one or more discovery messages including at least one of (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission; transmitting the one or more discovery messages to the base station; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; and triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the at least one selected relay.

[0016] According to some embodiments of the present disclosure, a non-transitory computer-readable medium storing instructions executable by one or more processors of a UE in communication to perform a method is provided, the method including: sending a relay selection request to a base station to be forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; and triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the at least one selected relay.

[0017] According to some embodiments of the present disclosure, a non-transitory computer-readable medium storing instructions executable by one or more processors of a relay for a UE in communication to perform a method is provided, the method including: transmitting one or more discovery messages to the UE, the one or more discovery messages including at least one of (1) one or more link quality parameters for one or more links between the UE and the relay, (2) an attachment status parameter indicating attachment of the relay to the base station, or (3) an availability status parameter indicating availability of the relay for multipath transmission; and transmitting one or more measurements to the base station regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating availability of the relay for multipath transmission.

[0018] According to some embodiments of the present disclosure, a UE in communication may receive a relay to perform the method. A non-transitory computer-readable medium storing instructions executable by one or more processors of a mobile station is provided. The method includes receiving a relay selection request from a base station, receiving one or more relay selection response messages from a UE, the one or more relay selection response messages including link quality parameters for one or more links between the UE and the relay, transmitting the received one or more relay selection response messages to the base station, and transmitting one or more measurements related to one or more signals transmitted between the base station and the relay to the base station, the one or more measurements including at least one of (1) one or more link quality parameters for the one or more links between the base station and the relay, or (2) one or more availability status parameters indicative of the availability of the relay for multipath transmission. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram illustrating multipath transmission in a communication system consistent with certain embodiments of the present disclosure. [Figure 2] FIG. 1 is a schematic diagram illustrating the challenges in relay selection (or reselection) for multipath transmission. [Figure 3] FIG. 1 is a schematic diagram illustrating a method for relay selection (or reselection), consistent with certain embodiments of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram illustrating a first approach for relay selection (or reselection), consistent with certain embodiments of the present disclosure. [Figure 5] FIG. 10 is a schematic diagram illustrating a second approach for relay selection (or reselection), consistent with certain embodiments of the present disclosure. [Figure 6] 1 is a schematic diagram illustrating a method for a base station for multipath communication consistent with certain embodiments of the present disclosure. [Figure 7] FIG. 1 is a schematic diagram illustrating a method for a UE for multipath communication, consistent with certain embodiments of the present disclosure. [Figure 8]FIG. 1 is a schematic diagram illustrating a method for a UE for multipath communication, consistent with certain embodiments of the present disclosure. [Figure 9] FIG. 1 is a schematic diagram illustrating a method for relaying for a UE in communication, consistent with certain embodiments of the present disclosure. [Figure 10] FIG. 1 is a schematic diagram illustrating a method for relaying for a UE in communication, consistent with certain embodiments of the present disclosure. [Figure 11] 1 is a block diagram of a UE consistent with certain embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0020] Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, in which like numbers in different drawings represent the same or similar elements unless otherwise stated. The implementations described in the following exemplary embodiments are not representative of all implementations consistent with the present disclosure. Rather, they are merely examples of systems, apparatus, and methods consistent with aspects related to the present disclosure, as set forth in the appended claims.

[0021] FIG. 1 is a schematic diagram illustrating multipath transmission in a communication system consistent with some embodiments of the present disclosure. Referring to FIG. 1, the communication system 100 includes a UE 102, a network 104, and a relay 106. The network may be a base station (e.g., a gNB). The relay 106 may be a UE-to-network (U2N) relay. The relay 106 may be another UE in the communication system attached to the network 104. As shown in FIG. 1, the UE 102 may be connected to the network 104 using a direct path (path #1) and an indirect path (path #2) via the relay 106 for multipath transmission. In some embodiments, multiple indirect paths via multiple relays may exist. possible.

[0022] Referring to FIG. 1 , when a relay 106 is attached to a network 104, for example, using a Uu interface, information about the link between the relay 106 and the network 104 is known to the network 104. The information about the link between the relay 106 and the network 104 may include, for example, the relay's Uu Quality of Service (QoS) characteristics (e.g., channel conditions) and availability status (e.g., network attachment, workload). The availability status may include, for example, information about whether the relay 106 is attached to the network 104 and / or whether the relay 106's workload allows the relay 106 to perform the function of a relay for the UE 102. The information about the link between the relay 106 and the network 104 would be useful in determining whether to select (or reselect) the relay 106 as a relay for multipath transmission for the UE 102. However, under existing technology, information about the link between the relay 106 and the network 104 is not known to the UE 102.

[0023] Also, when the UE 102 discovers and selects the relay 106 by itself, the UE 102 and the relay 106 form a link, for example, via a PC5 interface. Information about the link between the UE 102 and the relay 106 is known to the UE 102. The information about the link between the UE 102 and the relay 106 may include, for example, PC5 QoS characteristics, the availability status of the relay 106, etc. The availability status of the relay 106 may include, for example, information about network attachment (e.g., whether the relay 106 is attached to the network 104) and / or information about the workload of the relay 106. However, under existing technology, information about the link between the UE 102 and the relay 106 is not known to the network 104. As a result, the end-to-end quality of the indirect path (path #2) cannot be guaranteed, and the performance of the entire multipath transmission may be degraded.

[0024] Figure 2 is a schematic diagram illustrating challenges in relay selection (or reselection) for multipath transmission. Referring to Figure 2, the communication system includes a UE 202, two networks 204, 226, four U2N relays 206, 214, 216, 218, and three non-U2N relays 208, 210, 212. The two networks 204 and 226 may be base stations (e.g., gNBs). The non-U2N relays 208, 210, and 212 are not attached to any network. The communication system 200 includes two types of connections (links): UE-to-UE connections via a PC5 interface, indicated by circle 222, and UE-to-network connections via a Uu interface, indicated by circle 224 (Uu1 interface) and circle 220 (Uu2 interface). Of the four U2N relays, U2N relays 214, 216, and 218 are attached to network 204 via Uu1, and U2N relay 206 is attached to network 226 via Uu2. UE 202 is attached to network 204 via the Uu1 interface. Through the PC5 connection, UE 202 can find six candidate relays by itself: U2N relay 206, relay 208, relay 210, relay 212, U2N relay 216, and U2N relay 214. Of these six candidate relays, only three relays (214, 216, and 206) are attached to networks (204 or 226) and therefore can be any U2N relays, while the remaining three relays (208, 210, and 212) cannot be U2N relays. And, of the three U2N relays, U2N relay 206 is attached to network 226, which is not the same network as the network to which UE 202 is attached (network 204). Therefore, U2N relay 206 cannot be a candidate U2N relay for UE 202. That is, of the six relays that UE 202 finds, only two of them are This presents a challenge in selecting a relay that may be a candidate U2N relay for a UE 202. At least some embodiments of the present disclosure address the above challenge by providing a relay selection (or reselection) method with network assistance (or guidance) to facilitate end-to-end quality of the indirect path in a multipath transmission using U2N relays.

[0025] FIG. 3 is a schematic diagram illustrating a method for relay selection (or reselection) consistent with some embodiments of the present disclosure. Referring to FIG. 3 , a communication system 300 includes a UE 302, a network 304, and a relay 306. The UE 302 may be any device, such as a mobile phone, a wireless handheld device, a wireless personal device, a computer, a laptop computer, a vehicle, a vehicle-mounted component, or any other form. The network 304 may be any network, such as a base station. The base station may be any currently existing base station (e.g., eNB, gNB) for Long Term Evolution (LTE) or New Radio (NR), or a base station for a future generation (sixth generation (6G), or any other future generation) radio access technology (RAT). The relay 306 may be a U2N relay. In some embodiments, the U2N relay may be another UE. In some embodiments, the UE 302 is a vehicle in vehicle-to-everything (V2X) communications, and the U2N relay is a roadside unit. 3, the UE 302 may be connected to the network 304 using a direct path (path #1) and an indirect path (path #2) via a relay 306 for multipath transmission. In some embodiments, the UE 302 uses multiple indirect paths to communicate with a base station via multiple relays.

[0026] 3 , indirect path #2 includes two links: a first link between the UE 302 and the relay 306, e.g., via a PC5 interface, and a second link between the relay 306 and the network 304, e.g., via a Uu interface. Characteristics of the first link between the UE 302 and the relay 306 (e.g., link QoS parameters, attachment, availability, etc.) are known to the UE 302 but unknown to the network 304. Meanwhile, characteristics of the link between the relay 306 and the network 304 are known to the network 304 but unknown to the UE 302. At least some embodiments of the present disclosure are directed to combining a priori knowledge of the UE 302 and the network 304 and considering the end-to-end quality of indirect path #2 to assist in the selection (or reselection) of a suitable U2N relay, thereby improving communication reliability and accuracy.

[0027] FIG. 4 is a schematic diagram illustrating a first approach for relay selection (or reselection) consistent with some embodiments of the present disclosure. Referring to FIG. 4, a communication system 400 includes a UE 402, a network 404, and a relay 406. The UE 402, the network 404, and the relay 406 are similar to the UE 302, the network 304, and the relay 306, respectively, of FIG. 3. For brevity, detailed descriptions of the UE 402, the network 404, and the relay 406 are omitted here. The first approach is also referred to as a "UE-find-relay" approach. In the first approach, as shown in FIG. 4, at step 410, the UE 402 receives a relay selection response message from the relay 406. In some embodiments, the UE 402 may first send a relay selection request message to the relay 406 and receive a relay selection response message in response. The term "message" as used in this disclosure may be anything carried in a communication, such as information, signal(s), or data. Also, a "message" as used in this disclosure may be a single message or multiple messages. In some embodiments, at least one of a relay selection request message or a relay selection response message is sent during a device-to-device (D2D) discovery procedure between the UE 402 and the relay 406. In some embodiments, the relay selection response message may include at least one of: (1) one or more link quality parameters for the link between the UE 402 and the relay 406; (2) one or more attachment status parameters indicating the attachment of the relay 406 to the network 404; or (3) one or more availability status parameters indicating the availability of the relay 406 to be a relay for the UE 402. In some embodiments, the one or more link quality parameters for the link between the UE 402 and the relay 406 may include at least one of one or more sidelink reference signal received power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE 402 and the relay 406 or one or more sidelink discovery reference signal received power (SD-RSRP) values ​​measured on one or more discovery messages during the discovery procedure.

[0028] In step 412, the UE 402 sends a relay selection response message to the network 404 so that the network 404 has knowledge of the characteristics of the link between the UE 402 and the relay 406.

[0029] In step 414, the relay 406 transmits a measurement message to the network 404. The measurement message may be one or more measurement reports for one or more measurements performed by the relay 406 on signals (e.g., downlink signals) transmitted between the network 404 and the relay 406. In some embodiments, the one or more measurements include at least one of: (1) one or more link quality parameters for the link between the relay 406 and the network 404; or (2) one or more availability status parameters indicating the availability of the relay 406 for multipath transmissions. In some embodiments, the one or more link quality parameters for the link between the relay 406 and the network 404 may include at least one of one or more Reference Signal Received Power (RSRP) values ​​measured on one or more signals transmitted between the relay 406 and the network 404; or one or more Reference Signal Received Quality (RSRQ) values ​​measured on one or more signals transmitted between the relay 406 and the network 404.

[0030] In step 416, the network 404 determines whether the relay 406 meets the relay selection criteria based on at least one of the relay selection response message received from the UE 402 or the measurement message received from the relay 406. In some embodiments, the relay selection criteria may include at least one of: (1) one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE 402 and the relay 404 exceeding an SL-RSRP threshold; (2) one or more SD-RSRP values ​​measured on one or more discovery messages exceeding an SD-RSRP threshold; (3) RSRP values ​​measured on one or more signals transmitted between the relay 406 and the network 404 exceeding an RSRP threshold; or (4) RSRQ values ​​measured on one or more signals transmitted between the relay 406 and the network 404 exceeding an RSRQ threshold.

[0031] In step 418, based on the determination result in step 416, the network 404 selects the relay 406 as a relay for the UE 402 and transmits the selection result to the UE 402. The UE 402 may then trigger multipath transmission using the relay 406 as a U2N relay. In this manner, accuracy and reliability of the relay selection (or reselection) are ensured by providing the network 404 with both a relay selection response message containing characteristics of the link between the UE 402 and the relay 406 and a measurement message containing characteristics of the link between the relay 406 and the network 404.

[0032] FIG. 4 shows only one relay, namely, relay 406, as an exemplary candidate relay. In some embodiments, there are multiple candidate relays in the communication system, and the network 404 may select one or more relays from the multiple candidate relays. In this case, the UE 402 may communicate with the network 404 using a multipath transmission that includes one or more indirect paths through the selected one or more relays.

[0033] FIG. 5 is a schematic diagram illustrating a second approach for relay selection (or reselection) consistent with some embodiments of the present disclosure. Referring to FIG. 5, a communication system 500 includes a UE 502, a network 504, and a relay 506. The UE 502, the network 504, and the relay 506 are similar to the UE 302, the network 304, and the relay 306, respectively, of FIG. 3. For brevity, detailed descriptions of the UE 502, the network 504, and the relay 506 are omitted here. The second approach is also referred to as a "Relay-find-UE" approach. In this approach, as shown in FIG. 5, in step 510, the UE 502 sends a relay selection request message to the network 504. Then, in step 512, the network 504 forwards the received relay selection request message to the relay 506. The relay selection request message can provide information regarding the UE 502 or a transmission scheduled at the UE 502.

[0034] In step 514, the relay 506 receives a relay selection response message from the UE 502. In some embodiments, the relay selection response message is a discovery message sent during a D2D discovery procedure. In some embodiments, the relay selection response message may include one or more link quality parameters for the link between the UE 502 and the relay 506.

[0035] In step 516, the relay 506 forwards the received relay selection response message to the network 504. In addition, the relay 506 also transmits a measurement message to the network 504. The measurement message may be one or more measurement reports for measurements performed by the relay 506 on signals (e.g., downlink signals) transmitted between the relay 506 and the network 504. In some embodiments, the one or more measurements include at least one of: (1) one or more link quality parameters for the link between the relay 506 and the network 504, or (2) one or more availability status parameters indicating the availability of the relay 506 to be a relay in multipath transmissions. In some embodiments, the one or more link quality parameters for the link between the relay 506 and the network 504 may include at least one of one or more RSRP values ​​measured on one or more signals transmitted between the relay 506 and the network 504, or one or more RSRQ values ​​measured on one or more signals transmitted between the relay 506 and the network 504.

[0036] In step 518, the network 504 determines whether the relay 506 meets the relay selection criteria based on at least one of the relay selection response message or the measurement message received from the relay 506. In some embodiments, the relay selection criteria may include at least one of: (1) one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE 502 and the relay 504 exceeding an SL-RSRP threshold; (2) one or more SD-RSRP values ​​measured on one or more discovery messages exceeding an SD-RSRP threshold; (3) RSRP values ​​measured on one or more signals transmitted between the relay 506 and the network 504 exceeding an RSRP threshold; or (4) RSRQ values ​​measured on one or more signals transmitted between the relay 506 and the network 504 exceeding an RSRQ threshold.

[0037] In step 520, based on the determination result in step 518, 504 may select relay 506 as a relay for UE 502 and transmit the selection result to UE 502. UE 502 may then trigger multipath transmission using relay 506 as a U2N relay. In this way, accuracy and reliability of relay selection (or reselection) are ensured by providing network 504 with both a relay selection response message containing characteristics of the link between UE 502 and relay 506 and a measurement message containing characteristics of the link between relay 506 and network 504.

[0038] 5 shows only one relay, namely, relay 506, as an exemplary candidate relay, embodiments of the present disclosure are not so limited. In some embodiments, there are multiple candidate relays in the communication system, and the network 504 may select one or more relays from the multiple candidate relays. In this case, the UE 502 may communicate with the network 504 using a multipath transmission that includes one or more indirect paths through the selected one or more relays.

[0039] FIG. 6 is a schematic diagram illustrating a method for a base station for multipath communication, consistent with some embodiments of the present disclosure. The base station may be any currently existing base station (e.g., eNB, gNB) for LTE or NR, or a base station for a future generation (6G or any other future generation) RAT. For example, the base station may be network 404 of FIG. 4 or network 504 of FIG. 5. Referring to FIG. 6, method 600 includes step 602 of receiving, by the base station, one or more discovery messages communicated between a UE and one or more candidate relays, where the UE and the one or more candidate relays are attached to the base station. The one or more candidate relays may include at least one of one or more UEs different from the UE or one or more roadside units attached to the base station. The one or more discovery messages may include at least one of (1) one or more relay selection requests or (2) one or more relay selection response messages indicating one or more responses to the one or more relay selection requests. The one or more discovery messages may include at least one of: (1) one or more link quality parameters for one or more links between the UE and one or more candidate relays, (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission. The one or more link quality parameters for the one or more links between the UE and one or more candidate relays may include at least one of one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE and one or more candidate relays or one or more SD-RSRP values ​​measured on one or more discovery messages.

[0040] In a first embodiment, the base station is a base station such as network 404 in FIG. 4. The UE and one or more candidate relays are attached to the base station, for example, via a Uu interface. In this embodiment, the base station receives one or more discovery messages (e.g., relay selection response messages) from the UE that are communicated between the UE and one or more candidate relays. In this embodiment, the one or more discovery messages are obtained by the UE from one or more candidate relays and forwarded to the base station. The one or more discovery messages may be one or more selection response messages and may include at least one of (1) one or more link quality parameters for one or more links between the UE and one or more candidate relays, or (2) one or more attachment status parameters that indicate attachment of the one or more candidate relays to the base station.

[0041] In a second embodiment, the base station is a base station such as network 504 of FIG. 5. In this embodiment, the base station receives from one or more relays one or more discovery messages (e.g., relay selection response messages) communicated between the UE and one or more candidate relays. In this embodiment, the one or more discovery messages are received from the UE by one or more candidate relays. The one or more discovery messages may be one or more selection response messages and may include one or more link quality parameters for one or more links between the UE and one or more candidate relays.

[0042] The method 600 includes step 604 of receiving, by the base station, one or more measurements for one or more signals transmitted between the base station and one or more candidate relays. For example, in a first embodiment (e.g., FIG. 4), the base station receives one or more measurements for one or more signals transmitted between the base station and one or more candidate relays. In a second embodiment (e.g., FIG. 5), the base station also receives one or more measurements for one or more signals transmitted between the base station and one or more candidate relays. The one or more measurements may include at least one of (1) one or more link quality parameters for one or more links between the base station and one or more candidate relays, or (2) one or more availability status parameters indicative of the availability of the one or more candidate relays for multipath transmissions.

[0043] The method 600 includes step 606 of determining, by the base station, whether one or more candidate relays meet the relay selection criteria based on at least one of the one or more discovery messages or one or more measurements. For example, in a first embodiment (e.g., FIG. 4), the base station determines whether one or more candidate relays meet the relay selection criteria based on at least one of the one or more discovery messages received from the UE or one or more measurements received from the one or more candidate relays. In a second embodiment (e.g., FIG. 5), the base station determines whether one or more candidate relays meet the relay selection criteria based on at least one of the one or more discovery messages or one or more measurements received from the one or more candidate relays.

[0044] The method 600 includes step 608, by the base station, selecting at least one relay from the one or more candidate relays for multipath transmission for the UE based on the determining. In some embodiments, the base station may transmit a selection result to the UE so that the UE can trigger multipath transmission. The multipath transmission may include a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay. The relay selection criteria may include at least one of (1) one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays exceeding an SL-RSRP threshold, or (2) one or more SD-RSRP values ​​measured on one or more discovery messages exceeding an SD-RSRP threshold. Additionally or alternatively, the relay selection criteria may include at least one of (1) an RSRP value measured on one or more signals transmitted between the base station and the one or more candidate relays exceeding an RSRP threshold, or (2) an RSRQ value measured on one or more signals transmitted between the base station and the one or more candidate relays exceeding an RSRQ threshold.

[0045] FIG. 7 is a schematic diagram illustrating a method for a UE for multipath communication consistent with some embodiments of the present disclosure. For example, a UE, such as UE 402 of FIG. 4, is attached to a base station. Referring to FIG. 7, method 700 includes step 702 of receiving one or more discovery messages from one or more candidate relays attached to the base station. The one or more candidate relays may be at least one of one or more UEs different from the UE or one or more roadside units attached to the base station. In some embodiments, the one or more discovery messages may include at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission. In some embodiments, the one or more link quality parameters for one or more links between the UE and the one or more candidate relays may include at least one of: The data may include at least one of one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE and one or more candidate relays or one or more SD-RSRP values ​​measured on one or more discovery messages.

[0046] The method 700 includes transmitting one or more discovery messages to a base station 704. For example, the UE transmits the one or more discovery messages to the base station so that the base station can have knowledge of characteristics of links between the UE and one or more candidate relays.

[0047] The method 700 includes receiving, from the base station, information regarding at least one relay selected from the one or more candidate relays 706. For example, the base station selects at least one relay from the one or more candidate relays based on at least one of characteristics of links between the UE and the one or more candidate relays received from the UE or information regarding links between the base station and the one or more candidate relays, and transmits information about the selected at least one relay to the UE.

[0048] The method 700 includes triggering 708 a multipath transmission. For example, the UE may trigger a multipath transmission using the selected at least one relay. The multipath transmission may include a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0049] FIG. 8 is a schematic diagram illustrating a method for a UE for multipath communication consistent with some embodiments of the present disclosure. For example, a UE, such as UE 502 of FIG. 5, is attached to a base station. Referring to FIG. 8, method 800 includes step 802 of sending a relay selection request to a base station so that the relay selection request can be forwarded to one or more candidate relays attached to the base station. The one or more candidate relays may be one or more UEs different from the UE or one or more roadside units attached to the base station. For example, in some embodiments, the UE may send a relay selection request to the base station so that the relay selection request can be forwarded to one or more candidate relays attached to the base station. The relay selection request may include information about the UE or any scheduled transmissions from the UE.

[0050] The method 800 includes a step 804 of transmitting one or more relay selection response messages to the one or more candidate relays. For example, after transmitting the relay selection request, the UE may transmit the one or more relay selection response messages, e.g., during a D2D discovery procedure. The one or more relay selection response messages may include one or more link quality parameters for one or more links between the UE and the one or more candidate relays. The one or more link quality parameters for the one or more links between the UE and the one or more candidate relays may include at least one of one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays or one or more SD-RSRP values ​​measured on one or more discovery messages. The one or more candidate relays may further transmit the received one or more relay selection response messages to the base station along with measurements performed on signals transmitted between the one or more candidate relays and the base station.

[0051] The method 800 includes receiving 806, from the base station, information regarding at least one relay selected from the one or more candidate relays. For example, upon receiving the one or more relay selection response messages and the measurement results, the base station selects at least one relay from the one or more candidate relays and transmits information regarding the selected at least one relay to the UE.

[0052] The method 800 includes triggering 808 a multipath transmission based on the selected at least one relay. The multipath transmission may include a direct path between the UE and the base station and a selected relay. The method may include an indirect path between the UE and the base station via at least one selected relay.

[0053] FIG. 9 is a schematic diagram illustrating a method for relaying for multipath communication, consistent with some embodiments of the present disclosure. The relay may be a candidate U2N relay for a UE in communication. The relay and the UE may be attached to the same base station. For example, a relay (e.g., relay 406 in FIG. 4) is a candidate relay for a UE (e.g., UE 402 in FIG. 4) attached to the base station. Referring to FIG. 9, method 900 includes step 902 of transmitting one or more discovery messages to the UE. The one or more discovery messages may include at least one of: (1) one or more link quality parameters for one or more links between the UE and the relay; (2) an attachment status parameter indicating attachment of the relay to the base station; or (3) an availability status parameter indicating availability of the relay for multipath transmission. The UE may further transmit the received one or more discovery messages to the base station. The one or more link quality parameters for the one or more links between the UE and the one or more candidate relays may include at least one of one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays or one or more SD-RSRP values ​​measured on one or more discovery messages.

[0054] The method 900 includes transmitting 904 one or more measurements to the base station regarding one or more signals transmitted between the base station and the relay. The one or more measurements may include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating the availability of the relay for multipath transmission. In some embodiments, the one or more link quality parameters for the one or more links between the base station and the relay may include at least one of one or more RSRP values ​​measured on one or more signals transmitted between the base station and the relay or one or more RSRQ values ​​measured on one or more signals transmitted between the base station and the relay. Based on at least one of the one or more discovery messages received from the UE or the one or more measurements received from the relay, the base station can determine whether the relay is a preferred relay for the UE.

[0055] FIG. 10 is a schematic diagram illustrating a method for relaying for multipath communication, consistent with some embodiments of the present disclosure. The relay may be a candidate U2N relay for a UE in the communication. The relay and the UE may be attached to the same base station. For example, a relay (e.g., relay 506 in FIG. 5) is a candidate relay for a UE (e.g., UE 502 in FIG. 5) attached to the base station. Referring to FIG. 10, method 1000 includes step 1002 of receiving a relay selection request from a base station. For example, in some embodiments, the base station may receive the relay selection request from the UE and forward it to the relay. The relay selection request may include information about the UE or any scheduled transmissions from the UE.

[0056] The method 1000 includes step 1004 of receiving one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the relay. For example, the relay may receive one or more relay selection response messages from the UE during a D2D discovery procedure. The one or more relay selection response messages may include one or more link quality parameters for the links between the UE and the relay. The one or more link quality parameters may include at least one of one or more SL-RSRP values ​​measured on one or more sidelink signals transmitted between the UE and the relay or one or more SD-RSRP values ​​measured on one or more discovery messages.

[0057] The method 1000 includes transmitting one or more received relay selection response messages to a base station. Step 1006 is included. For example, the relay may further transmit the received one or more relay selection response messages to the base station.

[0058] The method 1000 includes transmitting 1008 to the base station one or more measurements related to one or more signals transmitted between the base station and the relay. The one or more measurements may include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission. Based on at least one of the one or more relay selection response messages or the one or more measurements received from the relay, the base station can determine whether the relay is a preferred relay for the UE.

[0059] The methods described in this disclosure may be applied to any communication, such as LTE or NR or future generation (e.g., 6G or any future generation) communication. The methods described in this disclosure may also be applied to communication involving any number of UEs. The methods described in this disclosure may also be applied to other systems, such as systems that comply with other standards (e.g., Institute of Electrical and Electronics Engineers (IEEE) standards), such as IEEE 802.11 technology.

[0060] FIG. 11 is a block diagram of a UE 1100 consistent with some embodiments of the present disclosure. For example, the UE 1100 may be the UE 402 of FIG. 4 or the UE 502 of FIG. 5 that triggers multipath transmission. Alternatively, the UE 1100 may be a relay UE (e.g., a U2N relay) that performs a relay function for another UE. For example, the UE 1100 may be the relay 406 of FIG. 4 or the relay 506 of FIG. 5. The UE 1100 may be mounted in a moving vehicle or a fixed location. The UE 1100 may take any form, including, but not limited to, a vehicle, a component mounted in a vehicle, a roadside unit, a laptop computer, a wireless terminal including a mobile phone, a wireless handheld device, or a wireless personal device, or any other form.

[0061] 11 , a UE 1100 may include an antenna 1102 that may be used for transmitting or receiving electromagnetic signals to / from a base station or other UEs. The antenna 1102 may include one or more antenna elements and may enable different input / output antenna configurations, such as a multiple-input multiple-output (MIMO) configuration, a multiple-input single-output (MISO) configuration, and a single-input multiple-output (SIMO) configuration. In some embodiments, the antenna 1102 may include multiple (e.g., tens or hundreds) antenna elements and may enable multi-antenna functions such as beamforming. In some embodiments, the antenna 1102 is a single antenna.

[0062] The UE 1100 may include a transceiver 1104 coupled to an antenna 1102. The transceiver 1104 may be a wireless transceiver in the UE 1100 and may communicate bidirectionally with a base station or another UE. For example, the transceiver 1104 may receive / transmit wireless signals to / from a base station via downlink / uplink communication. The transceiver 1104 may also receive / transmit wireless signals from / to another UE or roadside unit via sidelink communication. The transceiver 1104 may include a modem for modulating packets, providing the modulated packets to the antenna 1102 for transmission, and demodulating packets received from the antenna 1102.

[0063] The UE 1100 may include memory 1106. The memory 1106 may be any type of computer-readable storage medium, including volatile or non-volatile memory devices, or a combination thereof. Computer-readable storage media include, but are not limited to, non-transitory computer storage media. Non-transitory storage media may be accessed by a general-purpose or special-purpose computer. Examples of non-transitory storage media include portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable logic (PG), and the like. Non-transitory media may include, but are not limited to, programmable read-only memory (EPROM), electrically erasable programmable ROM (EEPROM), digital versatile disk (DVD), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, etc. Non-transitory media may be used to carry or store desired program code means (e.g., instructions and / or data structures) and may be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. In some examples, software / program code may be transmitted from a remote source (e.g., a website, server, etc.) using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave. In such examples, coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are within the definition of media. Combinations of the above examples are also within the scope of computer-readable media.

[0064] The memory 1106 may store information related to the identification of the UE 1100 and signals and / or data received by the antenna 1102. The memory 1106 may also store post-processed signals and / or data. The memory 1106 may also store computer-readable program instructions, mathematical models, and algorithms used in signal processing in the receiver 1104 and calculations in the processor 1108. The memory 1106 may further store computer-readable program instructions for execution by the processor 1108 to operate the UE 1100 to perform various functions described in this disclosure. In some examples, the memory 1106 may include a basic input / output system (BIOS) that may control basic hardware or software operations such as interaction with peripheral components or devices.

[0065] The computer-readable program instructions of the present disclosure may be assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​and conventional procedural programming languages. The computer-readable program instructions may be executed entirely on a computing device as a standalone software package, or may be executed partially on a first computing device and partially on a second computing device remote from the first computing device. In the latter scenario, the second, remote computing device may be connected to the first computing device via any type of network, including a local area network (LAN) or a wide area network (WAN).

[0066] The UE 1100 may include a processor 1108, which may include hardware devices having processing capabilities. The processor 1108 may include at least one of a general-purpose processor, a digital signal processor (DSP), a central processing unit (CPU), a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device, discrete gate or transistor logic components, discrete hardware components, or other programmable logic devices. Examples of general-purpose processors include, but are not limited to, a microprocessor, any conventional processor, controller, microcontroller, or state machine. In some embodiments, the processor 1108 may be implemented using a combination of 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). The processor 1108 receives downlink or sidelink signals from the transceiver 1104 and updates the signals. The processor 1108 may also receive data packets from the transceiver 1104 and further process the packets. In some embodiments, the processor 1108 may be configured to operate the memory using a memory controller. In some embodiments, the memory controller may be integrated into the processor 1108. The processor 1108 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1106) to cause the UE 1100 to perform various functions.

[0067] The UE 1100 may include a global positioning system (GPS) 1110. The GPS 1110 may be used to enable location-based services or other services based on the geographic position of the UE 1100 and / or synchronization between UEs. The GPS 1110 may receive global navigation satellite system (GNSS) signals from a single satellite signal or multiple satellite signals via the antenna 1102 and provide the geographic position of the UE 1100 (e.g., coordinates of the UE 1100). In some embodiments, the GPS 1110 is omitted. In some embodiments, a timer is included.

[0068] The UE 1100 may include input / output (I / O) devices 1112 that can be used to communicate the results of signal processing and calculations to a user or another device. The I / O devices 1112 may include a user interface including a display and input devices for sending user commands to the processor 1108. The display may be configured to display the status of signal reception at the UE 1100, data stored in the memory 1106, the status of signal processing, and the results of calculations. The display may include, but is not limited to, a cathode ray tube (CRT), a liquid crystal display (LCD), a light-emitting diode (LED), a gas plasma display, a touchscreen, or other image projection devices for displaying information to a user. The input devices may be any type of computer hardware equipment used to receive data and control signals from a user. The input devices may include, but are not limited to, a keyboard, a mouse, a scanner, a digital camera, a joystick, a trackball, cursor direction keys, a touchscreen monitor, an audio / video commander, or the like.

[0069] The UE 1100 may further include a machine interface 1114, such as an electrical bus, that connects the transceiver 1104, the memory 1106, the processor 1108, the GPS 1110, and the I / O device 1112.

[0070] In some embodiments, the UE 1100 may be a UE planning to perform multipath transmission in communication with a base station. The processor 1108 may be configured or programmed to execute instructions stored in the memory 1106 to: receive one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission; transmit the one or more discovery messages to the base station; receive from the base station information regarding at least one relay selected from the one or more candidate relays; and trigger multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the at least one selected relay.

[0071] In some embodiments, the UE 1100 may be a UE that plans to perform multipath transmission in communication with a base station. the UE may be configured or programmed to execute instructions to: send a relay selection request to a base station to be forwarded to one or more candidate relays attached to the base station; send one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receive from the base station information regarding at least one relay selected from the one or more candidate relays; and trigger multi-path transmission, the multi-path transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the at least one selected relay.

[0072] In some embodiments, the UE 1100 may be a candidate relay UE for another UE planning to communicate with a base station through multipath transmissions. The processor 1108 may be configured or programmed to execute instructions stored in the memory 1106 to: send one or more discovery messages to the UE, the one or more discovery messages including at least one of (1) one or more link quality parameters for one or more links between the UE and the relay, (2) an attachment status parameter indicating attachment of the relay to the base station, or (3) an availability status parameter indicating availability of the relay for multipath transmissions; and send one or more measurements to the base station regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating availability of the relay for multipath transmissions.

[0073] In some embodiments, the UE 1100 may be a candidate relay UE for another UE planning to communicate with a base station through multipath transmissions. The processor 1108 may be configured or programmed to execute instructions stored in the memory 1106 to: receive a relay selection request from a base station; receive one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the relay; transmit the received one or more relay selection response messages to the base station; and transmit one or more measurements related to one or more signals transmitted between the base station and the relay to the base station, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmissions.

[0074] As used in this disclosure, the use of the word "or" in a list of items indicates an inclusive list. The list of items may be prefaced by a phrase such as "at least one of" or "one or more of." For example, a list of at least one of A, B, or C includes A or B or C or AB (i.e., A and B) or AC or BC or ABC (i.e., A and B and C). Also, as used in this disclosure, prefacing a list of conditions with the phrase "based on" should not be construed as "based only on" the set of conditions, but rather as "based at least in part on" the set of conditions. For example, a result described as "based on condition A" could be based on both condition A and condition B without departing from the scope of this disclosure.

[0075] As used herein, the terms "comprise," "include," or "contain" may be used interchangeably, have the same meaning, and should be construed as being inclusive and open-ended. The terms "include," "contain," or "included" may be used before a list of elements to indicate that at least all of the listed elements in the list are present, but that other elements not in the list may also be present. For example, if A contains B and C, then both {B,C} and {B,C,D} are within the scope of A.

[0076] The present disclosure describes exemplary configurations in connection with the accompanying drawings, which do not represent all examples that may be implemented or all configurations within the scope of the present disclosure. The term "exemplary" should not be interpreted as "preferred" or "advantageous over other examples," but rather as "an example, instance, or example." By reading this disclosure, including the description of the embodiments and drawings, those skilled in the art will understand that the technology disclosed herein may be implemented using alternative embodiments. Those skilled in the art will understand that the embodiments described herein, or specific features of the embodiments, may be combined to arrive at yet other embodiments for implementing the technology described in this disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0077] The flowcharts and block diagrams in the figures illustrate example architecture, functionality, and operation of possible implementations of systems, methods, and devices according to various embodiments. It should be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the functionality involved. Likewise, additional steps may be included in methods consistent with various embodiments, and certain steps may be omitted or combined.

[0078] It is to be understood that the described embodiments are not mutually exclusive, and that elements, components, materials, or steps described in connection with one exemplary embodiment may be combined with or excluded from other embodiments in any suitable manner to achieve desired design objectives.

[0079] References herein to "some embodiments" or "some exemplary embodiments" mean that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment. The appearances of the phrases "one embodiment," "some embodiments," or "another embodiment" in various places in this disclosure do not necessarily all refer to the same embodiments, and separate or alternative embodiments are not necessarily mutually exclusive of other embodiments.

[0080] Furthermore, the articles "a" and "an," as used in this disclosure and the appended claims, should generally be construed to mean "one or more," unless otherwise specified or unless it is clear from the context that the singular form is intended.

[0081] Unless expressly stated otherwise, each numerical value and range should be construed as approximate, as if the word "about" or "approximately" preceded the value or range value.

[0082] Although elements in the following method claims, if any, are recited in a particular order, those elements are not necessarily intended to be limited to being implemented in that particular order, unless the recitation of a claim otherwise implies a particular order for implementing some or all of those elements.

[0083] It is to be appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Various features herein that are described in the context of a single embodiment for purposes of simplicity may also be provided separately or in any suitable subcombination, or as appropriate, in any other described embodiment herein. Particular features described in the context of various embodiments are not essential features of those embodiments, unless so described.

[0084] It will be further understood that various modifications, substitutions, and variations in the details, materials, and arrangements of parts described and illustrated to illustrate the nature of the described embodiments may be made by those skilled in the art without departing from the scope thereof, and therefore the following claims will encompass all such substitutions, modifications, and variations that fall within the terms of the claims.

[0085] Clause 1: A method for selecting at least one relay for a user equipment (UE) in a communication system, the method comprising: receiving, by a base station, one or more discovery messages communicated between the UE and one or more candidate relays, wherein the UE and the one or more candidate relays are attached to the base station; receiving, by the base station, one or more measurements regarding one or more signals transmitted between the base station and the one or more candidate relays; determining, by the base station, whether the one or more candidate relays meet a relay selection criterion based on at least one of the one or more discovery messages or the one or more measurements; selecting, by the base station and based on the determining, at least one relay from the one or more candidate relays for multipath transmission for the UE.

[0086] Clause 2: The method of clause 1, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE, or one or more roadside units attached to the base station.

[0087] Clause 3: The method of clause 1, wherein the one or more discovery messages include at least one of (1) one or more relay selection requests, or (2) one or more relay selection response messages indicating one or more responses to the one or more relay selection requests.

[0088] Clause 4: The method of clause 1, wherein the one or more discovery messages include at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission.

[0089] Clause 5: The method of clause 4, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays include at least one of one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays, or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

[0090] Clause 6: The relay selection criteria is one of: (1) the one or more SL-RSRP values ​​measured on the one or more sidelink signals transmitted between the UE and the one or more candidate relays exceed an SL-RSRP threshold; or (2) the one or more SD-RSRP values ​​measured on the one or more discovery messages exceed an SD-RSRP threshold. 6. The method of clause 5, comprising at least one

[0091] Clause 7: The method of clause 1, wherein the one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0092] Clause 8: The method of clause 7, wherein the one or more link quality parameters for the one or more links between the base station and the one or more candidate relays include at least one of one or more RSRP values ​​measured on one or more signals transmitted between the base station and the one or more candidate relays, or one or more RSRQ values ​​measured on the one or more signals transmitted between the base station and the one or more candidate relays.

[0093] Clause 9: The method of clause 8, wherein the relay selection criteria include at least one of (1) the RSRP value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRP threshold, or (2) the RSRQ value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRQ threshold.

[0094] Clause 10: Receiving the one or more discovery messages communicated between the UE and the one or more candidate relays includes: The method of clause 1 further includes receiving from the UE the one or more discovery messages obtained from the one or more candidate relays, the one or more discovery messages being one or more selection response messages and including at least one of (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, or (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station.

[0095] Clause 11: Receiving the one or more measurements on the one or more signals transmitted between the base station and the one or more candidate relays comprises: The method of clause 10, further comprising receiving the one or more measurements from the one or more candidate relays, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0096] Clause 12: Receiving the one or more discovery messages communicated between the UE and the one or more candidate relays includes: The method of clause 1, further comprising receiving from the one or more candidate relays the one or more discovery messages obtained from the UE, the one or more discovery messages being one or more selection response messages and including one or more link quality parameters for one or more links between the UE and the one or more candidate relays.

[0097] Clause 13: Receiving the one or more discovery messages communicated between the UE and the one or more candidate relays includes: forwarding one or more relay selection requests received from the UE to the one or more candidate relays; receiving, from the one or more candidate relays, one or more relay selection response messages obtained from the UE in response to the one or more relay selection requests. 12. The method according to claim 12.

[0098] Clause 14: Receiving the one or more measurements on the one or more signals transmitted between the base station and the one or more candidate relays comprises: 13. The method of claim 12, further comprising receiving the one or more measurements from the one or more candidate relays, the one or more measurements comprising at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0099] Clause 15: The method of clause 1, further comprising transmitting the selected at least one relay to the UE to trigger the multipath transmission at the UE, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0100] Clause 16: A method for a user equipment (UE), the UE being attached to a base station in a communication system, the method comprising: receiving one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission; transmitting the one or more discovery messages to the base station; receiving information from the base station regarding at least one relay selected from the one or more candidate relays; triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0101] Clause 17: The method of clause 16, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE, or one or more roadside units attached to the base station.

[0102] Clause 18: The method of clause 16, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays include at least one of one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays, or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

[0103] Clause 19: A method for a user equipment (UE), the UE being attached to a base station in a communication system, the method comprising: sending a relay selection request to the base station so that the relay selection request is forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving information from the base station regarding at least one relay selected from the one or more candidate relays; triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0104] Clause 20: The method of clause 19, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE, or one or more roadside units attached to the base station.

[0105] Clause 21: The method of clause 19, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays include at least one of one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays, or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

[0106] Clause 22: A method for a relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station, the method comprising: sending one or more discovery messages to the UE, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the relay; (2) an attachment status parameter indicating attachment of the relay to the base station; or (3) an availability status parameter indicating availability of the relay for multipath transmission; transmitting to the base station one or more measurements regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

[0107] Clause 23: A method for a relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station, the method comprising: receiving a relay selection request from the base station; receiving one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; transmitting to the base station one or more measurements relating to one or more signals transmitted between the base station and the relay; The method, wherein the one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission.

[0108] Clause 24: A base station in a communication system, the base station comprising: a memory for storing instructions; a processor, the processor executing the instructions stored in the memory to one or more discovery messages communicated between the UE and the one or more candidate relays. receiving, wherein the UE and the one or more candidate relays are attached to the base station; receiving one or more measurements on one or more signals transmitted between the base station and the one or more candidate relays; determining whether the one or more candidate relays meet relay selection criteria based on at least one of the one or more discovery messages or the one or more measurements; and selecting at least one relay from the one or more candidate relays for multipath transmission for the UE.

[0109] Clause 25: The base station of clause 24, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE, or one or more roadside units attached to the base station.

[0110] Clause 26: A base station as described in Clause 24, wherein the one or more discovery messages include at least one of (1) one or more relay selection requests, or (2) one or more relay selection response messages indicating one or more responses to the one or more relay selection requests.

[0111] Clause 27: The base station described in Clause 24, wherein the one or more discovery messages include at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission.

[0112] Clause 28: The base station described in Clause 27, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays include at least one of one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more signals transmitted between the UE and the one or more candidate relays, or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

[0113] Clause 29: The base station described in Clause 28, wherein the relay selection criteria include at least one of (1) the one or more SL-RSRP values ​​measured on the one or more sidelink signals transmitted between the UE and the one or more candidate relays exceeding an SL-RSRP threshold, or (2) the one or more SD-RSRP values ​​measured on the one or more discovery messages exceeding an SD-RSRP threshold.

[0114] Clause 30: The base station described in Clause 24, wherein the one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0115] Clause 31: The base station described in Clause 30, wherein the one or more link quality parameters for the one or more links between the base station and the one or more candidate relays include at least one of one or more RSRP values ​​measured on one or more signals transmitted between the base station and the one or more candidate relays, or one or more RSRQ values ​​measured on the one or more signals transmitted between the base station and the one or more candidate relays.

[0116] Clause 32: The base station described in Clause 31, wherein the relay selection criteria include at least one of (1) the RSRP value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRP threshold, or (2) the RSRQ value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRQ threshold.

[0117] Clause 33: The processor executes the instructions stored in the memory, The base station of clause 24, further configured to receive from the UE the one or more discovery messages obtained from the one or more candidate relays, the one or more discovery messages being one or more selection response messages and including at least one of (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, or (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station.

[0118] Clause 34: The processor executes the instructions stored in the memory. The base station of clause 33, further configured to receive the one or more measurements from the one or more candidate relays, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0119] Clause 35: The processor executes the instructions stored in the memory, The base station of clause 24, further configured to receive from the one or more candidate relays the one or more discovery messages obtained from the UE, the one or more discovery messages being one or more selection response messages and including one or more link quality parameters for one or more links between the UE and the one or more candidate relays.

[0120] Clause 36: The processor executes the instructions stored in the memory, forwarding one or more relay selection requests received from the UE to the one or more candidate relays; and receiving, from the one or more candidate relays, one or more relay selection response messages obtained from the UE in response to the one or more relay selection requests.

[0121] Clause 37: The processor executes the instructions stored in the memory. The base station of clause 35, further configured to receive the one or more measurements from the one or more candidate relays, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0122] Clause 38: The processor executes the instructions stored in the memory, The base station of clause 24, further comprising transmitting the selected at least one relay to the UE to trigger the multipath transmission at the UE, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0123] Clause 39: A user equipment (UE) for communication, the UE being attached to a base station, the UE comprising: a memory for storing instructions; a processor, the processor executing the instructions stored in the memory to receiving one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission; transmitting the one or more discovery messages to the base station; receiving information from the base station regarding at least one relay selected from the one or more candidate relays; and triggering a multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0124] Clause 40: The UE of clause 39, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

[0125] Clause 41: The UE described in Clause 39, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays include at least one of one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more signals transmitted between the UE and the one or more candidate relays, or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

[0126] Clause 42: A user equipment (UE) for communication, the UE being attached to a base station, the UE comprising: a memory for storing instructions; a processor, the processor executing the instructions stored in the memory to sending a relay selection request to the base station so that the relay selection request is forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving information from the base station regarding at least one relay selected from the one or more candidate relays; A UE, triggering a multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0127] Clause 43: The UE of clause 42, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

[0128] Clause 44: The one or more link quality parameters for the one or more links between the UE and the one or more candidate relays are 43. The UE of claim 42, wherein the UE comprises at least one of one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the UE, or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

[0129] Clause 45: A relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station, the relay comprising: a memory for storing instructions; a processor, the processor executing the instructions stored in the memory to sending one or more discovery messages to the UE, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the relay; (2) an attachment status parameter indicating attachment of the relay to the base station; or (3) an availability status parameter indicating availability of the relay for multipath transmission; a UE configured to: transmit to the base station one or more measurements regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

[0130] Clause 46: A relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station, the relay comprising: a memory for storing instructions; a processor, the processor executing the instructions stored in the memory to receiving a relay selection request from the base station; receiving one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; transmitting to the base station one or more measurements relating to one or more signals transmitted between the base station and the relay; The UE, wherein the one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission.

[0131] Clause 47: A non-transitory computer-readable medium storing instructions executable by one or more processors of a base station for communication to perform a method for relay selection, the method comprising: receiving one or more discovery messages communicated between the UE and one or more candidate relays, wherein the UE and the one or more candidate relays are attached to the base station; and receiving one or more measurements on one or more signals transmitted between the base station and the one or more candidate relays; determining whether the one or more candidate relays meet relay selection criteria based on at least one of the one or more discovery messages or the one or more measurements. and, and selecting at least one relay from the one or more candidate relays for multipath transmission for the UE based on the determining.

[0132] Clause 48: A non-transitory computer-readable medium storing instructions executable by one or more processors of a user equipment (UE) for communication to perform a method, the method comprising: receiving one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission; transmitting the one or more discovery messages to the base station; receiving information from the base station regarding at least one relay selected from the one or more candidate relays; and triggering a multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0133] Clause 49: A non-transitory computer-readable medium storing instructions executable by one or more processors of a user equipment (UE) for communication to perform a method, the method comprising: sending a relay selection request to the base station so that the relay selection request is forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving information from the base station regarding at least one relay selected from the one or more candidate relays; Triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

[0134] Clause 50: A non-transitory computer-readable medium storing instructions executable by one or more processors of a relay for a user equipment (UE) in a communication to perform a method, the method comprising: sending one or more discovery messages to the UE, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the relay; (2) an attachment status parameter indicating attachment of the relay to the base station; or (3) an availability status parameter indicating availability of the relay for multipath transmission; transmitting to the base station one or more measurements relating to one or more signals transmitted between the base station and the relay, the one or more measurements being (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) ) including at least one of availability status parameters indicating the availability of the relay for the multipath transmission.

[0135] Clause 51: A non-transitory computer-readable medium storing instructions executable by one or more processors of a relay for a user equipment (UE) in a communication to perform a method, the method comprising: receiving a relay selection request from the base station; receiving one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for a link between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; transmitting to the base station one or more measurements relating to one or more signals transmitted between the base station and the relay; The one or more measurements include at least one of: (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicative of the availability of the relay for multipath transmission.

Claims

1. 1. A method for selecting at least one relay for a user equipment (UE) in a communication system, comprising: receiving, by a base station, one or more discovery messages communicated between the UE and one or more candidate relays, wherein the UE and the one or more candidate relays are attached to the base station; receiving, by the base station, one or more measurements regarding one or more signals transmitted between the base station and the one or more candidate relays; determining, by the base station, whether the one or more candidate relays satisfy a relay selection criterion based on at least one of the one or more discovery messages or the one or more measurements; selecting, by the base station and based on the determining, at least one relay from the one or more candidate relays for multipath transmission for the UE.

2. The method of claim 1 , wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

3. 2. The method of claim 1, wherein the one or more discovery messages include at least one of: (1) one or more relay selection requests; or (2) one or more relay selection response messages indicating one or more responses to the one or more relay selection requests.

4. 2. The method of claim 1, wherein the one or more discovery messages include at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission.

5. 5. The method of claim 4, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays comprise at least one of: one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays; or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

6. 6. The method of claim 5, wherein the relay selection criteria include at least one of: (1) the one or more SL-RSRP values ​​measured on the one or more sidelink signals transmitted between the UE and the one or more candidate relays exceed an SL-RSRP threshold; or (2) the one or more SD-RSRP values ​​measured on the one or more discovery messages exceed an SD-RSRP threshold.

7. 2. The method of claim 1, wherein the one or more measurements include at least one of: (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays; or (2) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission.

8. for the one or more links between the base station and the one or more candidate relays.

8. The method of claim 7, wherein the one or more link quality parameters include at least one of one or more RSRP values ​​measured on one or more signals transmitted between the base station and the one or more candidate relays or one or more RSRQ values ​​measured on the one or more signals transmitted between the base station and the one or more candidate relays.

9. 9. The method of claim 8, wherein the relay selection criteria include at least one of: (1) the RSRP value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRP threshold; or (2) the RSRQ value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRQ threshold.

10. receiving the one or more discovery messages communicated between the UE and the one or more candidate relays; 2. The method of claim 1, further comprising receiving from the UE the one or more discovery messages obtained from the one or more candidate relays, the one or more discovery messages being one or more selection response messages and including at least one of (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, or (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station.

11. Receiving the one or more measurements on the one or more signals transmitted between the base station and the one or more candidate relays includes:

11. The method of claim 10, further comprising receiving the one or more measurements from the one or more candidate relays, the one or more measurements comprising at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicative of availability of the one or more candidate relays for the multipath transmission.

12. receiving the one or more discovery messages communicated between the UE and the one or more candidate relays; 2. The method of claim 1, further comprising receiving, from the one or more candidate relays, the one or more discovery messages obtained from the UE, wherein the one or more discovery messages are one or more selection response messages and include one or more link quality parameters for one or more links between the UE and the one or more candidate relays.

13. receiving the one or more discovery messages communicated between the UE and the one or more candidate relays; forwarding one or more relay selection requests received from the UE to the one or more candidate relays; 13. The method of claim 12, further comprising: receiving, from the one or more candidate relays, one or more relay selection response messages obtained from the UE in response to the one or more relay selection requests.

14. Receiving the one or more measurements on the one or more signals transmitted between the base station and the one or more candidate relays includes:

13. The method of claim 12, further comprising receiving the one or more measurements from the one or more candidate relays, the one or more measurements comprising at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicative of availability of the one or more candidate relays for the multipath transmission.

15. 2. The method of claim 1, further comprising: transmitting the selected at least one relay to the UE to trigger the multipath transmission at the UE, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

16. 1. A method for a user equipment (UE) attached to a base station in a communication system, comprising: receiving one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission; transmitting the one or more discovery messages to the base station; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; triggering the multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

17. The method of claim 16 , wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

18. 17. The method of claim 16, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays comprise at least one of: one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays; or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

19. 1. A method for a user equipment (UE) attached to a base station in a communication system, comprising: sending a relay selection request to the base station so that the relay selection request is forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; triggering a multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

20. 20. The method of claim 19, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

21. 20. The method of claim 19, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays comprise at least one of: one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays; or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

22. 1. A method for a relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station; sending one or more discovery messages to the UE, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the relay; (2) an attachment status parameter indicating attachment of the relay to the base station; or (3) an availability status parameter indicating availability of the relay for multipath transmission; transmitting to the base station one or more measurements regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

23. 1. A method for a relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station; receiving a relay selection request from the base station; receiving one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; transmitting to the base station one or more measurements relating to one or more signals transmitted between the base station and the relay; The method, wherein the one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission.

24. A base station in a communication system, comprising: a memory for storing instructions; a processor, The processor executes the instructions stored in the memory to receiving one or more discovery messages communicated between the UE and the one or more candidate relays, the UE and the one or more candidate relays being attached to the base station; and receiving one or more measurements on one or more signals transmitted between the base station and the one or more candidate relays; determining whether the one or more candidate relays meet relay selection criteria based on at least one of the one or more discovery messages or the one or more measurements; selecting at least one relay from the one or more candidate relays for multipath transmission for the UE.

25. 25. The base station of claim 24, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

26. 25. The base station of claim 24, wherein the one or more discovery messages include at least one of: (1) one or more relay selection requests; or (2) one or more relay selection response messages indicating one or more responses to the one or more relay selection requests.

27. 25. The base station of claim 24, wherein the one or more discovery messages include at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for the multipath transmission.

28. 28. The base station of claim 27, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays comprise at least one of: one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more signals transmitted between the UE and the one or more candidate relays; or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

29. 29. The base station of claim 28, wherein the relay selection criteria include at least one of: (1) the one or more SL-RSRP values ​​measured on the one or more sidelink signals transmitted between the UE and the one or more candidate relays exceed an SL-RSRP threshold; or (2) the one or more SD-RSRP values ​​measured on the one or more discovery messages exceed an SD-RSRP threshold.

30. 25. The base station of claim 24, wherein the one or more measurements include at least one of: (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays; or (2) one or more availability status parameters indicative of availability of the one or more candidate relays for the multipath transmission.

31. 31. The base station of claim 30, wherein the one or more link quality parameters for the one or more links between the base station and the one or more candidate relays include at least one of one or more RSRP values ​​measured on one or more signals transmitted between the base station and the one or more candidate relays or one or more RSRQ values ​​measured on the one or more signals transmitted between the base station and the one or more candidate relays.

32. 32. The base station of claim 31 , wherein the relay selection criteria include at least one of: (1) the RSRP value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRP threshold; or (2) the RSRQ value measured on the one or more signals transmitted between the base station and the one or more candidate relays exceeds an RSRQ threshold.

33. The processor executes the instructions stored in the memory to and (2) receiving from the UE the one or more discovery messages obtained from the one or more candidate relays, the one or more discovery messages being one or more selection response messages, the one or more discovery messages including (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays, or (2) one or more link quality parameters for one or more links between the UE and the one or more candidate relays to the base station.

25. The base station of claim 24, further comprising at least one of one or more attachment status parameters indicative of attachment of a candidate relay to the base station.

34. The processor executes the instructions stored in the memory.

34. The base station of claim 33, further configured to receive the one or more measurements from the one or more candidate relays, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicative of availability of the one or more candidate relays for the multipath transmission.

35. The processor executes the instructions stored in the memory to 25. The base station of claim 24, further configured to receive, from the one or more candidate relays, the one or more discovery messages obtained from the UE, the one or more discovery messages being one or more selection response messages and including one or more link quality parameters for one or more links between the UE and the one or more candidate relays.

36. The processor executes the instructions stored in the memory to forwarding one or more relay selection requests received from the UE to the one or more candidate relays; 36. The base station of claim 35, further configured to: receive, from the one or more candidate relays, one or more relay selection response messages obtained from the UE in response to the one or more relay selection requests.

37. The processor executes the instructions stored in the memory.

36. The base station of claim 35, further configured to receive the one or more measurements from the one or more candidate relays, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the one or more candidate relays, or (2) one or more availability status parameters indicative of availability of the one or more candidate relays for the multipath transmission.

38. The processor executes the instructions stored in the memory to 25. The base station of claim 24, further comprising: transmitting the selected at least one relay to the UE to trigger the multipath transmission at the UE, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

39. A user equipment (UE) for communication attached to a base station, comprising: a memory for storing instructions; a processor, The processor executes the instructions stored in the memory to receiving one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more availability status parameters indicating availability of the one or more candidate relays for multipath transmission; transmitting the one or more discovery messages to the base station; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; and triggering the multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

40. 40. The UE of claim 39, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

41. 40. The UE of claim 39, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays comprise at least one of: one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more signals transmitted between the UE and the one or more candidate relays; or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

42. A user equipment (UE) for communication attached to a base station, comprising: a memory for storing instructions; a processor, The processor executes the instructions stored in the memory to sending a relay selection request to the base station so that the relay selection request is forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; A UE that triggers multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

43. 43. The UE of claim 42, wherein the one or more candidate relays comprise at least one of one or more UEs different from the UE or one or more roadside units attached to the base station.

44. 43. The UE of claim 42, wherein the one or more link quality parameters for the one or more links between the UE and the one or more candidate relays comprise at least one of: one or more Sidelink Reference Signal Received Power (SL-RSRP) values ​​measured on one or more sidelink signals transmitted between the UE and the one or more candidate relays; or one or more Sidelink Discovery Reference Signal Received Power (SD-RSRP) values ​​measured on the one or more discovery messages.

45. A relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station, the relay comprising: a memory for storing instructions; a processor, the processor executing the instructions stored in the memory to transmitting one or more discovery messages to the UE, the one or more discovery messages including: (1) one or more link quality parameters for one or more links between the UE and the relay; (2) an address indicating attachment of the relay to the base station; or (3) an availability status parameter indicating the availability of the relay for multipath transmission; a UE configured to: transmit to the base station one or more measurements regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

46. A relay for a user equipment (UE) in communication, the relay and the UE being attached to a base station, the relay comprising: a memory for storing instructions; a processor, the processor executing the instructions stored in the memory to receiving a relay selection request from the base station; receiving one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; transmitting to the base station one or more measurements relating to one or more signals transmitted between the base station and the relay; The one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission, to the UE.

47. 1. A non-transitory computer-readable medium storing instructions executable by one or more processors of a base station for communication to perform a method for relay selection, the method comprising: receiving one or more discovery messages communicated between the UE and one or more candidate relays, the UE and the one or more candidate relays being attached to the base station; and receiving one or more measurements on one or more signals transmitted between the base station and the one or more candidate relays; determining whether the one or more candidate relays meet relay selection criteria based on at least one of the one or more discovery messages or the one or more measurements; and selecting at least one relay from the one or more candidate relays for multipath transmission for the UE based on the determining.

48. 1. A non-transitory computer-readable medium storing instructions executable by one or more processors of a user equipment (UE) for communication to perform a method, the method comprising: receiving one or more discovery messages from one or more candidate relays attached to a base station, the one or more discovery messages including: (1) one or more link quality parameters for one or more links between the UE and the one or more candidate relays; (2) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station; or (3) one or more attachment status parameters indicating attachment of the one or more candidate relays to the base station for multipath transmission; at least one of one or more availability status parameters indicating availability of the receiver; transmitting the one or more discovery messages to the base station; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; and triggering the multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

49. 1. A non-transitory computer-readable medium storing instructions executable by one or more processors of a user equipment (UE) for communication to perform a method, the method comprising: sending a relay selection request to a base station so that the relay selection request is forwarded to one or more candidate relays attached to the base station; sending one or more relay selection response messages to the one or more candidate relays, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and the one or more candidate relays; receiving from the base station information regarding at least one relay selected from the one or more candidate relays; Triggering multipath transmission, the multipath transmission including a direct path between the UE and the base station and an indirect path between the UE and the base station via the selected at least one relay.

50. 1. A non-transitory computer-readable medium storing instructions executable by one or more processors of a relay for a user equipment (UE) in a communication to perform a method, the method comprising: sending one or more discovery messages to the UE, the one or more discovery messages including at least one of: (1) one or more link quality parameters for one or more links between the UE and the relay; (2) an attachment status parameter indicating attachment of the relay to a base station; or (3) an availability status parameter indicating availability of the relay for multipath transmission; and transmitting to the base station one or more measurements regarding one or more signals transmitted between the base station and the relay, the one or more measurements including at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

51. 1. A non-transitory computer-readable medium storing instructions executable by one or more processors of a relay for a user equipment (UE) in a communication to perform a method, the method comprising: receiving a relay selection request from a base station; receiving one or more relay selection response messages from the UE, the one or more relay selection response messages including one or more link quality parameters for a link between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; One or more measurements on one or more signals transmitted between the base station and the relay. and transmitting the signal to the base station; The one or more measurements include at least one of (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) one or more availability status parameters indicative of the availability of the relay for multipath transmission.

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