Selection of relays in sidelink communications

Abstract

Methods, apparatus, and systems for relay selection in communications are disclosed. The method includes receiving, by a base station, one or more discovery messages communicating between a UE and one or more candidate relays, the UE and the one or more candidate relays attached to the base station; receiving, by the base station, one or more measurements of 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 relay selection criteria based on at least one of: the one or more discovery messages, or the one or more measurements; and selecting, by the base station and based on the determination, at least one relay from the one or more candidate relays for multipath transmission of the UE.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 482,128, filed on January 30, 2023, entitled “SELECTION OF RELAY UES FORMULTI-PATH SIDELINK RELAYING COMMUNICATION,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] Apparatuses 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 Art

[0003] User Equipment (UE) can communicate with a base station using multipath transmission to improve the reliability and efficiency of communication. Multipath transmission can 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. The relay can be one or more other UEs in communication. For an indirect path, the 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 ensure the communication quality of these two links is important for the overall communication quality of the indirect path. However, relay selection (or reselection) is challenging 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 overall knowledge of the characteristics of both the first link and the second link, resulting in inaccuracy in relay selection, thereby reducing the quality of the indirect path. A system and method for reliable and accurate relay selection (or reselection) for multipath transmission is needed. 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 includes 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, the UE and the one or more candidate relays being attached to the base station; receive one or more measurements of 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 relay selection criteria based on at least one of the following: 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 of the UE.

[0005] According to some embodiments of the present disclosure, a UE for communication is provided. The UE includes a memory storing instructions; and a processor configured to execute the instructions stored in the memory 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 the following: (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 state parameters indicating the attachment of the one or more candidate relays to the base station, or (3) one or more availability state parameters indicating the availability of the one or more candidate relays for the multipath transmission; transmit the one or more discovery messages to the base station; receive at least one relay selected from the one or more candidate relays from the base station; 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 selected at least one relay.

[0006] According to some embodiments of the present disclosure, a UE for communication is provided. The UE includes: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: transmit 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; transmit 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 at least one relay selected from the one or more candidate relays from the base station; 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 selected at least one relay.

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

[0008] According to some embodiments of the present disclosure, a relay for a UE in communication is provided. The relay includes a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: receive a relay selection request from the 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 of 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 the following: (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.

[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, the UE and the one or more candidate relays being attached to the base station; receiving, by the base station, one or more measurements of 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 relay selection criteria based on at least one of the following: the one or more discovery messages or the one or more measurements; and selecting, by the base station and based on the determination, at least one relay from the one or more candidate relays for multipath transmission of the UE.

[0010] According to some embodiments of the present disclosure, a method for a UE is provided, wherein the UE is attached to a base station in a communication system. The method comprises: receiving one or more discovery messages from one or more candidate relays attached to the base station, the one or more discovery messages comprising at least one of the following: (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 state parameters indicating the attachment of the one or more candidate relays to the base station, or (3) one or more availability state parameters indicating the 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 about at least one relay selected from the one or more candidate relays from the base station; and triggering multipath transmission, wherein the multipath transmission comprises 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.

[0011] According to some embodiments of the present disclosure, a method for a UE is provided, wherein the UE is attached to a base station in a communication system. The method comprises: transmitting 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; transmitting 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 about at least one relay selected from the one or more candidate relays from the base station; and triggering multipath transmission, wherein the multipath transmission includes 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.

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

[0013] According to some embodiments of the present disclosure, a method for a relay of a UE in a communication system is provided, wherein the relay and the UE are attached to a base station. The method comprises: 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; and transmitting one or more measurements of 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 the following: (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.

[0014] According to some embodiments of the present disclosure, a non-transitory computer-readable medium is provided that stores instructions that are executable by one or more processors of a base station in communication to perform a method. The method includes: receiving one or more discovery messages communicated between a UE and one or more candidate relays, the UE and the one or more candidate relays being attached to the base station; receiving one or more measurements of 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 following: 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 of the UE based on the determination.

[0015] According to some embodiments of the present disclosure, a non-transitory computer-readable medium is provided, which stores instructions that can be executed by one or more processors of a UE in communication to perform a method. The method includes: 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 the following: (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 the attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating the 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 about at least one relay selected from the one or more candidate relays from the base station; 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 selected at least one relay.

[0016] According to some embodiments of the present disclosure, a non-transitory computer-readable medium is provided, which stores instructions that can be executed by one or more processors of a UE in communication to perform a method. The method includes: transmitting 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; transmitting 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 about at least one relay selected from the one or more candidate relays from the base station; 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 selected at least one relay.

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

[0018] According to some embodiments of the present disclosure, a non-transitory computer-readable medium is provided that stores instructions that can be executed by one or more processors of a relay for a UE in communication to perform a method. The method includes: 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; and transmitting one or more measurements of one or more signals transmitted between the base station and the relay to the base station, 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 relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0021] Figure 1 is a schematic diagram illustrating multipath transmission in a communication system consistent with some embodiments of the present disclosure. Figure 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 attached to the network 104 in the communication system. Figure 1As shown, UE 102 may connect to network 104 using a direct path (path #1) and an indirect path (path #2) via relay 106 for multipath transmission. In some embodiments, there may be multiple indirect paths via multiple relays.

[0022] Reference Figure 1 When relay 106 is attached to network 104, for example, using a Uu interface, network 104 knows information about the link between relay 106 and network 104. The information about the link between relay 106 and network 104 may include, for example, Uu quality of service (QoS) characteristics (e.g., channel conditions) and the availability status of the relay (e.g., network attachment, workload). The availability status may include, for example, information about whether relay 106 is attached to network 104 and / or whether the workload of relay 106 allows relay 106 to perform the function of a relay for UE 102. Information about the link between relay 106 and network 104 may be helpful in determining whether to select (or reselect) relay 106 as a relay for multipath transmission for UE 102. However, in the prior art, information about the link between relay 106 and network 104 is unknown to UE 102.

[0023] Furthermore, when UE 102 discovers and selects relay 106, UE 102 and relay 106 form a link, for example, via a PC5 interface. Information about the link between UE 102 and relay 106 is known to UE 102. Information about the link between UE 102 and relay 106 may include, for example, PC5 QoS characteristics, the availability status of relay 106, and the like. The availability status of relay 106 may include, for example, information about network attachment (e.g., whether relay 106 is attached to network 104) and / or information about the workload of relay 106. However, in the prior art, information about the link between UE 102 and relay 106 is unknown to network 104. Therefore, the end-to-end quality of the indirect path (#2) cannot be ensured, thereby reducing the overall performance of multipath transmission.

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

[0025] Figure 3 is a schematic diagram illustrating a method for relay selection (or reselection) consistent with some embodiments of the present disclosure. Figure 3, the communication system 300 includes a UE 302, a network 304, and a relay 306. The UE 302 can be any device, such as a mobile phone, a wireless handheld device, a wireless personal device, a computer, a laptop, a vehicle, a component installed in a vehicle, or any other form. The network 304 can be any network, such as a base station. The base station can 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 (6th generation (6G) or any other future generation) of Radio Access Technology (RAT). The relay 306 can be a U2N relay. In some embodiments, the U2N relay can be another UE. In some embodiments, the UE 302 is a vehicle in Vehicle-To-Everything (V2X) communication, and the U2N relay is a roadside unit. As Figure 3 As shown, UE 302 can connect to network 304 using a direct path (path #1) and an indirect path (path #2) via relay 306 for multipath transmission. In some embodiments, UE 302 communicates with a base station via multiple relays using multiple indirect paths.

[0026] refer to Figure 3 , indirect path #2 includes two links: a first link between UE 302 and relay 306 (e.g., via a PC5 interface), and a second link between relay 306 and network 304 (e.g., via a Uu interface). The characteristics of the first link between UE 302 and relay 306 (e.g., link QoS parameters, attachment, availability, etc.) are known to UE 302, but unknown to network 304. On the other hand, the characteristics of the link between relay 306 and network 304 are known to network 304, but unknown to UE 302. At least some embodiments of the present disclosure are directed to combining a priori knowledge of UE 302 and 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 the reliability and accuracy of communications.

[0027] Figure 4 is a schematic diagram illustrating a first method for relay selection (or reselection) consistent with some embodiments of the present disclosure. Figure 4 , the 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 Figure 3UE 302, network 304 and relay 306 in. For the sake of brevity, detailed description of UE 402, network 404 and relay 406 is omitted here. The first method is also called "UE finds relay" ("UE-find-relay") method. In the first method, as Figure 4 As shown, in step 410, UE 402 receives a relay selection response message from relay 406. In some embodiments, UE 402 may first transmit a relay selection request message to relay 406 and, in response, receive a relay selection response message. The term "message" as used in this disclosure may be anything conveyed in a communication, such as information, (one or more) signals, or data. In addition, a "message" as used in this disclosure may be a single message or multiple messages. In some embodiments, at least one of the relay selection request message or the relay selection response message is a discovery message transmitted during a device-to-device (D2D) discovery process between UE 402 and 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 state parameters indicating the attachment of the relay 406 to the network 404, or (3) one or more availability state parameters indicating the availability of the relay 406 as 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 for 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 for one or more discovery messages during a discovery process.

[0028] At step 412 , UE 402 transmits a relay selection response message to network 404 so that network 404 knows the characteristics of the link between UE 402 and relay 406 .

[0029] At 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 transmission. 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 for the one or more signals transmitted between the relay 406 and the network 404, or one or more Reference Signal Received Quality (RSRQ) values ​​measured for the 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 satisfies the relay selection criteria based on at least one of: a relay selection response message received from the UE 402, or a 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 for one or more sidelink signals transmitted between the UE 402 and the relay 404 exceeding a SL-RSRP threshold; (2) one or more SD-RSRP values ​​measured for one or more discovery messages exceeding a SD-RSRP threshold; (3) an RSRP value measured for one or more signals transmitted between the relay 406 and the network 404 exceeding a RSRP threshold; or (4) an RSRQ value measured for one or more signals transmitted between the relay 406 and the network 404 exceeding a RSRQ threshold.

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

[0032] although Figure 4Only one relay (i.e., relay 406) is shown as an example candidate relay, but embodiments of the present disclosure are not limited thereto. In some embodiments, there are multiple candidate relays in the communication system, and network 404 can select one or more relays from the multiple candidate relays. In this case, UE 402 can communicate with network 404 using multipath transmission including one or more indirect paths via the selected one or more relays.

[0033] Figure 5 is a schematic diagram illustrating a second method for relay selection (or reselection) consistent with some embodiments of the present disclosure. Figure 5 , the 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 Figure 3 UE 302, network 304 and relay 306. For the sake of brevity, detailed descriptions of UE 502, network 504 and relay 506 are omitted here. The second method is also called "Relay-find-UE" method. In this method, Figure 5 As shown, at step 510, UE 502 transmits a relay selection request message to network 504. And, at step 512, network 504 forwards the received relay selection request message to relay 506. The relay selection request message may provide information about UE 502 or a transmission scheduled at UE 502.

[0034] At step 514, relay 506 receives a relay selection response message from UE 502. In some embodiments, the relay selection response message is a discovery message transmitted during a D2D discovery process. In some embodiments, the relay selection response message may include one or more link quality parameters for the link between UE 502 and 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 can 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 the following: (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 as a relay in multipath transmission. In some embodiments, the one or more link quality parameters for the link between the relay 506 and the network 504 can include at least one of the following: one or more RSRP values ​​measured for one or more signals transmitted between the relay 506 and the network 504, or one or more RSRQ values ​​measured for one or more signals transmitted between the relay 506 and the network 504.

[0036] At step 518, the network 504 determines whether the relay 506 satisfies 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 the following: (1) one or more SL-RSRP values ​​measured for one or more sidelink signals transmitted between the UE 502 and the relay 504 exceed a SL-RSRP threshold; (2) one or more SD-RSRP values ​​measured for one or more discovery messages exceed a SD-RSRP threshold, (3) an RSRP value measured for one or more signals transmitted between the relay 506 and the network 504 exceeds an RSRP threshold, or (4) an RSRQ value measured for one or more signals transmitted between the relay 506 and the network 504 exceeds an RSRQ threshold.

[0037] At step 520, based on the determination result of step 518, network 504 may select relay 506 as the 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 manner, by providing network 504 with both a relay selection response message including characteristics of the link between UE 502 and relay 506 and a measurement message including characteristics of the link between relay 506 and network 504, accuracy and reliability of relay selection (or reselection) are ensured.

[0038] although Figure 5Only one relay (i.e., relay 506) is shown as an example candidate relay, but embodiments of the present disclosure are not limited thereto. In some embodiments, there are multiple candidate relays in the communication system, and the network 504 can select one or more relays from the multiple candidate relays. In this case, the UE 502 can communicate with the network 504 using multipath transmission including one or more indirect paths via the selected one or more relays.

[0039] Figure 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 Figure 4 Network 404 or Figure 5 Network 504. Reference Figure 6 , method 600 includes: step 602, receiving, by a base station, one or more discovery messages communicated between a UE and one or more candidate relays, the UE and the one or more candidate relays being attached to the base station. The one or more candidate relays may include at least one of the following: 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 the following: (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 the following: (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 the attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating the 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 the one or more candidate relays may include at least one of the following: one or more SL-RSRP values ​​measured for one or more sidelink signals transmitted between the UE and the one or more candidate relays, or one or more SD-RSRP values ​​measured for the one or more discovery messages.

[0040] In a first embodiment, the base station is such as Figure 4A base station of a network 404. 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) communicated between the UE and the one or more candidate relays from the UE. In this embodiment, the one or more discovery messages are obtained by the UE from the 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 the following: (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 state parameters indicating the attachment of the one or more candidate relays to the base station.

[0041] In a second embodiment, the base station is such as Figure 5 In one embodiment, the base station receives one or more discovery messages (e.g., relay selection response messages) from one or more relays, which are communicated between the UE and one or more candidate relays. In one embodiment, the one or more discovery messages are obtained from the UE by the 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 one or more link quality parameters for one or more links between the UE and the one or more candidate relays.

[0042] The method 600 includes: step 604, receiving, by the base station, one or more measurements of one or more signals transmitted between the base station and one or more candidate relays. For example, in the first embodiment (eg, Figure 4 ), the base station receives one or more measurements of one or more signals transmitted between the base station and one or more candidate relays. Figure 5 ), the base station also receives one or more measurements of 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 the following: (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 multipath transmission.

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

[0044] Method 600 includes: step 608, selecting, by the base station and based on the determination, at least one relay from one or more candidate relays for multipath transmission of the UE. In some embodiments, the base station may transmit the 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 the following: (1) one or more SL-RSRP values ​​measured for one or more sidelink signals transmitted between the UE and one or more candidate relays exceed an SL-RSRP threshold, or (2) one or more SD-RSRP values ​​measured for one or more discovery messages exceed an SD-RSRP threshold. Additionally or alternatively, the relay selection criteria may include at least one of the following: (1) an RSRP value measured for one or more signals transmitted between the base station and one or more candidate relays exceeds an RSRP threshold, or (2) an RSRQ value measured for one or more signals transmitted between the base station and one or more candidate relays exceeds an RSRQ threshold.

[0045] Figure 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 Figure 4 UE 402) is attached to the base station. Figure 7 , method 700 includes: step 702, 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 the following: one or more UEs different from the UE, or one or more road side units attached to the base station. In some embodiments, the one or more discovery messages may include at least one of the following: (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 state parameters indicating the attachment of the one or more candidate relays to the base station, or (3) one or more availability state parameters indicating the availability of the one or more candidate relays for multipath transmission. In some embodiments, 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 the following: one or more SL-RSRP values ​​measured for one or more sidelink signals transmitted between the UE and the one or more candidate relays, or one or more SD-RSRP values ​​measured for one or more discovery messages.

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

[0047] Method 700 includes receiving information about at least one relay selected from one or more candidate relays from a base station in step 706. For example, the base station selects the at least one relay from the one or more candidate relays based on at least one of the following: characteristics of a link between the UE and the one or more candidate relays received from the UE, or information about the link between the base station and the one or more candidate relays, and transmits the information about the selected at least one relay to the UE.

[0048] Method 700 includes: Step 708: Triggering multipath transmission. For example, the UE may trigger 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] Figure 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 Figure 5 UE 502) is attached to the base station. Figure 8 , method 800 includes: step 802, transmitting 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. 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 transmit a relay selection request to the base station, so that the relay selection request may 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] Method 800 includes: step 804, transmitting one or more relay selection response messages to one or more candidate relays. For example, after transmitting the relay selection request, the UE may transmit one or more relay selection response messages, for example during the D2D discovery process. 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 one or more links between the UE and the one or more candidate relays may include at least one of the following: one or more SL-RSRP values ​​measured for one or more sidelink signals transmitted between the UE and the one or more candidate relays, or one or more SD-RSRP values ​​measured for one or more discovery messages. The one or more candidate relays may also transmit the received one or more relay selection response messages together with the measurements performed on the signals transmitted between the one or more candidate relays and the base station to the base station.

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

[0052] The method 800 includes: triggering multipath transmission based on the selected at least one relay at step 808. 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.

[0053] Figure 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, the relay (e.g., Figure 4 The relay 406 in is used for UEs attached to the base station (e.g., Figure 4 UE 402) is a candidate relay. Figure 9, method 900 includes: step 902, transmitting one or more discovery messages to the UE. The one or more discovery messages may include at least one of the following: (1) one or more link quality parameters for one or more links between the UE and the relay, (2) an attachment state parameter indicating the attachment of the relay to the base station, or (3) an availability state parameter indicating the availability of the relay for multipath transmission. The UE may also transmit the received one or more discovery messages to the base station. The one or more link quality parameters for 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 for one or more sidelink signals transmitted between the UE and the one or more candidate relays, or one or more SD-RSRP values ​​measured for one or more discovery messages.

[0054] Method 900 includes: step 904, transmitting one or more measurements of one or more signals transmitted between the base station and the relay to the base station. The one or more measurements may include at least one of the following: (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 one or more links between the base station and the relay may include at least one of the following: one or more RSRP values ​​measured for one or more signals transmitted between the base station and the relay, or one or more RSRQ values ​​measured for one or more signals transmitted between the base station and the relay. The base station may determine whether the relay is a suitable relay for the UE based on at least one of the following: one or more discovery messages received from the UE, or one or more measurements received from the relay.

[0055] Figure 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 communication. The relay and the UE may be attached to the same base station. For example, the relay (e.g., Figure 5 The relay 506 in is used for UEs attached to the base station (e.g., Figure 5 Candidate relays for UE 502). Figure 10 Method 1000 includes: Step 1002, 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] Method 1000 includes receiving one or more relay selection response messages from a UE at step 1004, the one or more relay selection response messages including one or more link quality parameters for one or more links between the UE and a relay. For example, the relay may receive one or more relay selection response messages from the UE during a D2D discovery process. The one or more relay selection response messages may include one or more link quality parameters for the link between the UE and the relay. The one or more link quality parameters may include at least one of the following: one or more SL-RSRP values ​​measured for one or more sidelink signals transmitted between the UE and the relay, or one or more SD-RSRP values ​​measured for one or more discovery messages.

[0057] The method 1000 includes: step 1006, transmitting the received one or more relay selection response messages to the base station. For example, the relay may also transmit the received one or more relay selection response messages to the base station.

[0058] The method 1000 includes transmitting, to a base station, one or more measurements of one or more signals transmitted between the base station and the relay at step 1008. 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. The base station may determine whether the relay is a suitable relay for the UE based on at least one of: one or more relay selection response messages, or one or more measurements received from the relay.

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

[0060] Figure 11 is a block diagram of a UE 1100 consistent with some embodiments of the present disclosure. For example, the UE 1100 may be a UE that triggers multipath transmission. Figure 4 UE 402 or Figure 5 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 Figure 4Relay 406 or Figure 5 UE 1100 may be installed in a mobile vehicle or in a fixed location. UE 1100 may take any form, including but not limited to a vehicle, a component installed 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] Reference Figure 11 UE 1100 may include an antenna 1102, which may be used to transmit electromagnetic signals to / from a base station or other UEs. Antenna 1102 may include one or more antenna elements and may implement 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, antenna 1102 may include multiple (e.g., dozens or hundreds) of antenna elements and may implement multi-antenna functions, such as beamforming. In some embodiments, antenna 1102 is a single antenna.

[0062] UE 1100 may include a transceiver 1104 coupled to an antenna 1102. Transceiver 1104 may be a wireless transceiver at UE 1100 and may communicate bidirectionally with a base station or other UEs. For example, transceiver 1104 may receive or transmit wireless signals from or to a base station via downlink or uplink communications. Transceiver 1104 may also receive or transmit wireless signals from or to another UE or roadside unit via sidelink communications. Transceiver 1104 may include a modem that modulates packets and provides the modulated packets to antenna 1102 for transmission, and demodulates packets received from antenna 1102.

[0063] UE 1100 may include memory 1106. 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 can be accessed by general-purpose or special-purpose computers. Examples of non-transitory storage media include, but are not limited to, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable 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 devices, magnetic disk storage devices or other magnetic storage devices, and the like. Non-transitory media can be used to carry or store desired program code means (e.g., instructions and / or data structures) and can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. In some examples, software / program code can be transmitted from a remote source (e.g., a website, a server, etc.) using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves. In such examples, coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are within the scope of the definition of medium. Combinations of the above examples are also within the scope of computer-readable media.

[0064] The memory 1106 may store information related to the identity of the UE 1100 and the 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 for signal processing in the receiver 1104 and calculations in the processor 1108. The memory 1106 may also store computer-readable program instructions for execution by the processor 1108 to operate the UE 1100 to perform the various functions described in this disclosure. In some examples, the memory 1106 may include a basic input / output system (BIOS), which 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 can be assembly instructions, instruction set architecture (Instruction-Set-Architecture, ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data or source code or object code written in any combination of one or more programming languages, these programming languages ​​include object-oriented programming languages ​​and conventional process programming languages. The computer readable program instructions can be executed completely on a computing device as an independent software package, or partially on a first computing device and partially on a second computing device away from the first computing device. In the latter case, the second remote computing device can be connected to the first computing device through any type of network (including a local area network (LAN) or a wide area network (WAN)).

[0066] UE 1100 may include a processor 1108, which may include a hardware device with processing capabilities. Processor 1108 may include at least one of the following: 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, a controller, a microcontroller, or a state machine. In some embodiments, 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 combination with a DSP core, or any other such configuration). Processor 1108 may receive downlink signals or sidelink signals from transceiver 1104 and further process the signals. Processor 1108 may also receive data packets from 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., memory 1106) to enable the UE 1100 to perform different functions.

[0067] UE 1100 may include a Global Positioning System (GPS) 1110. GPS 1110 may be used to implement location-based services or other services based on the geographic location of UE 1100 and / or synchronization between UEs. GPS 1110 may receive Global Navigation Satellite System (GNSS) signals from a single satellite or multiple satellite signals via antenna 1102 and provide the geographic location of UE 1100 (e.g., coordinates of UE 1100). In some embodiments, GPS 1110 is omitted. In some embodiments, a timer is included.

[0068] UE 1100 may include an input / output (I / O) device 1112, which may be used to communicate the results of signal processing and calculations to a user or another device. I / O device 1112 may include a user interface, which includes a display and an input device for transmitting user commands to processor 1108. The display may be configured to display the status of signal reception at UE 1100, data stored in memory 1106, the status of signal processing, and calculation results. 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 touch screen, or other image projection device for displaying information to a user. The input device may be any type of computer hardware device for receiving data and control signals from a user. The input device may include, but is not limited to, a keyboard, a mouse, a scanner, a digital camera, a joystick, a trackball, cursor direction keys, a touch screen monitor, or audio / video commands.

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

[0070] In some embodiments, the UE 1100 may be a UE that plans to perform multipath transmission with a base station in communication. 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 the following: (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 state parameters indicating the attachment of the one or more candidate relays to the base station, or (3) one or more availability state parameters indicating the availability of the one or more candidate relays for multipath transmission; transmit the one or more discovery messages to the base station; receive information about at least one relay selected from the one or more candidate relays from the base station; 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 selected at least one relay.

[0071] In some embodiments, UE 1100 may be a UE that plans to perform multipath transmission with a base station in communication. Processor 1108 may be configured or programmed to execute instructions stored in memory 1106 to transmit 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; transmit 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 information about at least one relay selected from the one or more candidate relays from the base station; and trigger multipath transmission, wherein the multipath transmission includes 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.

[0072] In some embodiments, UE 1100 may be a candidate relay UE for another UE that plans to perform multipath transmission with a base station in communication. Processor 1108 may be configured or programmed to execute instructions stored in memory 1106 to transmit one or more discovery messages to the UE, the one or more discovery messages including at least one of the following: (1) one or more link quality parameters for one or more links between the UE and the relay, (2) an attachment state parameter indicating attachment of the relay to the base station, or (3) an availability state parameter indicating the availability of the relay for multipath transmission; and transmit one or more measurements of 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 the following: (1) one or more link quality parameters for one or more links between the base station and the relay, or (2) an availability state parameter indicating the availability of the relay for multipath transmission.

[0073] In some embodiments, UE 1100 may be a candidate relay UE for another UE that plans to perform multipath transmission with a base station in communication. Processor 1108 may be configured or programmed to execute instructions stored in memory 1106 to receive a relay selection request from the 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 of 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 the following: (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.

[0074] As used in this disclosure, the term "or" is used in a list of items to indicate an inclusive list. A list of items can begin with a phrase such as "at least one" or "one or more." 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). In addition, as used in this disclosure, pre-naming a list of conditions with the phrase "based on" should not be interpreted as "based only on" the set of conditions, but should be interpreted as "based at least in part on" the set of conditions. For example, a result described as "based on condition A" can be based on both condition A and condition B without departing from the scope of this disclosure.

[0075] In this specification, the terms "comprise," "includes," or "contain" are used interchangeably and have the same meaning and are to be interpreted as inclusive and open-ended. The terms "comprise," "include," or "contain" may precede a list of elements and indicate that at least all of the listed elements are present within the list, but additional elements not in the list may also be present. For example, if A includes B and C, both {B, C} and {B, C, D} are within the scope of A.

[0076] The present disclosure, in conjunction with the accompanying drawings, describes example configurations that are not representative of 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 embodiments," but rather as "an illustration, instance, or example." By reading this disclosure, including the description of the embodiments and the accompanying drawings, one of ordinary skill in the art will understand that the technology disclosed herein can be implemented using alternative embodiments. One of ordinary skill in the art will recognize that these embodiments, or certain features of the embodiments described herein, can be combined to obtain yet further embodiments for practicing 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 accompanying drawings illustrate examples of the architecture, functions, and operations of possible implementations of the systems, methods, and devices according to different embodiments. It should be noted that in some alternative embodiments, the functions indicated in the blocks may not occur in the order indicated in the figures. For example, depending on the functions involved, two blocks shown in succession may actually be performed substantially simultaneously, or these blocks may sometimes be performed in reverse order. Similarly, in methods consistent with different embodiments, additional steps may be included in such methods, and some steps may be omitted or combined.

[0078] It should be understood that the described embodiments are not mutually exclusive, and elements, components, materials, or steps described in conjunction with one exemplary embodiment may be combined with or eliminated from other embodiments in a suitable manner to achieve desired design goals.

[0079] References herein to "some embodiments" or "some exemplary embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment. The appearances of the phrases "one embodiment," "some embodiments," or "another embodiment" in various places throughout this disclosure do not necessarily all refer to the same embodiment, nor do they necessarily refer to separate or alternative embodiments that are mutually exclusive of other embodiments.

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

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

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

[0083] It should be understood that certain features of the present disclosure that are described in the context of separate embodiments for the sake of clarity may also be provided in combination in a single embodiment. Conversely, various features of this specification that are described in the context of a single embodiment for the sake of brevity may also be provided individually or in any suitable subcombination, or as appropriate in any other described embodiment of this specification. Certain features described in the context of various embodiments are not essential features of those embodiments unless so indicated.

[0084] It will be further understood that, without departing from the scope, those skilled in the art may make various modifications, substitutions and changes to the details, materials and arrangements of the components described and illustrated to explain the nature of the described embodiments. Therefore, the following claims cover all such substitutions, modifications and changes 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, the UE and the one or more candidate relays being attached to the base station; receiving, by the base station, one or more measurements of 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 relay selection criteria based on at least one of: the one or more discovery messages, or the one or more measurements; and At least one relay is selected, by the base station and based on the determination, 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 include 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: A method according to clause 1, wherein the one or more discovery messages include at least one of the following: (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: A method according to clause 1, wherein the one or more discovery messages include at least one of the following: (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 the attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0089] Clause 5: A method according to 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 the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

[0090] Clause 6: A method according to clause 5, wherein the relay selection criteria include at least one of the following: (1) the one or more SL-RSRP values ​​measured for 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 for the one or more discovery messages exceed an SD-RSRP threshold.

[0091] Clause 7: A method according to clause 1, wherein the one or more measurements include at least one of the following: (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: A method according to 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 the following: one or more RSRP values ​​measured for one or more signals transmitted between the base station and the one or more candidate relays, or one or more RSRQ values ​​measured for the one or more signals transmitted between the base station and the one or more candidate relays.

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

[0094] Clause 10: The method of clause 1, wherein receiving the one or more discovery messages communicated between the UE and the one or more candidate relays further comprises: The one or more discovery messages obtained from the one or more candidate relays are received from the UE, 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 state parameters indicating attachment of the one or more candidate relays to the base station.

[0095] Clause 11: The method of clause 10, wherein receiving the one or more measurements of the one or more signals transmitted between the base station and the one or more candidate relays further comprises: The one or more measurements are received 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 availability of the one or more candidate relays for the multipath transmission.

[0096] Clause 12: The method of clause 1, wherein receiving the one or more discovery messages communicated between the UE and the one or more candidate relays further comprises: The one or more discovery messages obtained from the UE are received from the one or more candidate relays, 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: The method of clause 12, wherein receiving the one or more discovery messages communicated between the UE and the one or more candidate relays further comprises: forwarding one or more relay selection requests received from the UE to the one or more candidate relays; and In response to the one or more relay selection requests, one or more relay selection response messages obtained from the UE are received from the one or more candidate relays.

[0098] Clause 14: The method of clause 12, wherein receiving the one or more measurements of the one or more signals transmitted between the base station and the one or more candidate relays further comprises: The one or more measurements are received from the one or more candidate relays, the one or more measurements comprising at least one of: 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: The selected at least one relay is transmitted to the UE to trigger 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, from the base station, information about at least one relay selected from the one or more candidate relays; and Multipath transmission is triggered, where the multipath transmission includes 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 include 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: A method according to 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 the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for 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: transmitting a relay selection request to the base station such that the relay selection request is forwarded to one or more candidate relays attached to the base station; transmitting 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 about at least one relay selected from the one or more candidate relays; and Multipath transmission is triggered, where the multipath transmission includes 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 include 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: A method according to 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 the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

[0106] Clause 22: A method for a relay of a user equipment (UE) in communication, the relay and the UE being attached to a base station, the method comprising: 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 state parameter indicating attachment of the relay to the base station, or (3) an availability state parameter indicating availability of the relay for multipath transmission; and One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 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 of 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; and One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 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 communications system, the base station comprising: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: receiving one or more discovery messages communicated between a UE and one or more candidate relays, the UE and the one or more candidate relays being attached to the base station; receiving one or more measurements of one or more signals transmitted between the base station and the one or more candidate relays; determining whether the one or more candidate relays satisfy relay selection criteria based on at least one of: the one or more discovery messages, or the one or more measurements; and At least one relay is selected from the one or more candidate relays for multipath transmission of the UE.

[0109] Clause 25: A base station as described in clause 24, wherein the one or more candidate relays include 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 according to clause 24, wherein the one or more discovery messages include at least one of the following: (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: A base station according to clause 24, wherein the one or more discovery messages include at least one of the following: (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 the attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

[0112] Clause 28: A base station according to 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 the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

[0113] Clause 29: A base station according to clause 28, wherein the relay selection criteria include at least one of the following: (1) the one or more SL-RSRP values ​​measured for 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 for the one or more discovery messages exceed an SD-RSRP threshold.

[0114] Clause 30: A base station according to 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: A base station according to 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 the following: one or more RSRP values ​​measured for one or more signals transmitted between the base station and the one or more candidate relays, or one or more RSRQ values ​​measured for the one or more signals transmitted between the base station and the one or more candidate relays.

[0116] Clause 32: A base station according to clause 31, wherein the relay selection criteria include at least one of the following: (1) the RSRP value measured for 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 for 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 base station of clause 24, wherein the processor is further configured to execute the instructions stored in the memory to: The one or more discovery messages obtained from the one or more candidate relays are received from the UE, 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 state parameters indicating attachment of the one or more candidate relays to the base station.

[0118] Clause 34: The base station of clause 33, wherein the processor is further configured to execute the instructions stored in the memory to: The one or more measurements are received 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 availability of the one or more candidate relays for the multipath transmission.

[0119] Clause 35: The base station of clause 24, wherein the processor is further configured to execute the instructions stored in the memory to: The one or more discovery messages obtained from the UE are received from the one or more candidate relays, 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 base station of clause 35, wherein the processor is further configured to execute 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; and In response to the one or more relay selection requests, one or more relay selection response messages obtained from the UE are received from the one or more candidate relays.

[0121] Clause 37: The base station of clause 35, wherein the processor is further configured to execute the instructions stored in the memory to: The one or more measurements are received from the one or more candidate relays, the one or more measurements comprising at least one of: 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 base station of clause 24, wherein the processor is further configured to execute the instructions stored in the memory to: The selected at least one relay is transmitted to the UE to trigger 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: User equipment (UE) for communication, the UE being attached to a base station, the UE comprising: a memory storing instructions; and a processor configured to execute 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, from the base station, information about at least one relay selected from the one or more candidate relays; and Multipath transmission is triggered, where the multipath transmission includes 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: A UE as described in clause 39, wherein the one or more candidate relays include 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: A UE according to 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 the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

[0126] Clause 42: User equipment (UE) for communication, the UE being attached to a base station, the UE comprising: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: transmitting a relay selection request to the base station such that the relay selection request is forwarded to one or more candidate relays attached to the base station; transmitting 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 about at least one relay selected from the one or more candidate relays; and Multipath transmission is triggered, where the multipath transmission includes 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: A UE as described in clause 42, wherein the one or more candidate relays include 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: A UE according to clause 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 include at least one of the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

[0129] Clause 45: A relay for a communicating user equipment (UE), the relay and the UE being attached to a base station, the relay comprising: a memory storing instructions; and a processor configured to execute the instructions stored in the memory to: 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 state parameter indicating attachment of the relay to the base station, or (3) an availability state parameter indicating availability of the relay for multipath transmission; and One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

[0130] Clause 46: A relay for a communicating user equipment (UE), the relay and the UE being attached to a base station, the relay comprising: a memory storing instructions; and a processor configured to execute 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; and One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 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 communications to perform a method for relay selection, the method comprising: receiving one or more discovery messages communicated between a UE and one or more candidate relays, the UE and the one or more candidate relays being attached to the base station; receiving one or more measurements of one or more signals transmitted between the base station and the one or more candidate relays; determining whether the one or more candidate relays satisfy relay selection criteria based on at least one of: the one or more discovery messages, or the one or more measurements; and Based on the determination, at least one relay is selected from the one or more candidate relays for multipath transmission of the UE.

[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 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, from the base station, information about at least one relay selected from the one or more candidate relays; and Multipath transmission is triggered, where the multipath transmission includes 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 comprising: transmitting a relay selection request to a base station such that the relay selection request is forwarded to one or more candidate relays attached to the base station; transmitting 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 about at least one relay selected from the one or more candidate relays; and Multipath transmission is triggered, where the multipath transmission includes 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 communication to perform a method comprising: 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 state parameter indicating attachment of the relay to the base station, or (3) an availability state parameter indicating availability of the relay for multipath transmission; and One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 relay, or (2) an availability status parameter 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 communication to perform a 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; and One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission.

Claims

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, the UE and the one or more candidate relays being attached to the base station; receiving, by the base station, one or more measurements of 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; as well as At least one relay is selected, by the base station and based on the determination, from the one or more candidate relays for multipath transmission for the UE.

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

3. The method according to 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. The method according to claim 1, wherein The one or more discovery messages include at least one of the following: (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 the attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

5. The method according to 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 include at least one of the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

6. The method according to claim 5, wherein: The relay selection criteria include at least one of the following: (1) the one or more SL-RSRP values ​​measured for 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 for the one or more discovery messages exceed an SD-RSRP threshold.

7. The method according to 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 the availability of the one or more candidate relays for the multipath transmission.

8. The method according to claim 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 the following: one or more RSRP values ​​measured for one or more signals transmitted between the base station and the one or more candidate relays, or one or more reference signal received quality (RSRQ) values ​​measured for the one or more signals transmitted between the base station and the one or more candidate relays.

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

10. The method according to claim 1, wherein Receiving the one or more discovery messages communicated between the UE and the one or more candidate relays further includes: The one or more discovery messages obtained from the one or more candidate relays are received from the UE, 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 state parameters indicating attachment of the one or more candidate relays to the base station.

11. The method according to claim 10, wherein: Receiving the one or more measurements of the one or more signals transmitted between the base station and the one or more candidate relays further comprises: The one or more measurements are received 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 availability of the one or more candidate relays for the multipath transmission.

12. The method according to claim 1, wherein Receiving the one or more discovery messages communicated between the UE and the one or more candidate relays further includes: The one or more discovery messages obtained from the UE are received from the one or more candidate relays, 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.

13. The method according to claim 12, wherein: Receiving the one or more discovery messages communicated between the UE and the one or more candidate relays further includes: forwarding one or more relay selection requests received from the UE to the one or more candidate relays; and In response to the one or more relay selection requests, one or more relay selection response messages obtained from the UE are received from the one or more candidate relays.

14. The method according to claim 12, wherein: Receiving the one or more measurements of the one or more signals transmitted between the base station and the one or more candidate relays further comprises: The one or more measurements are received from the one or more candidate relays, the one or more measurements comprising at least one of: 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.

15. The method according to claim 1, further comprising: The selected at least one relay is transmitted to the UE to trigger 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. 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, from the base station, information about at least one relay selected from the one or more candidate relays; as well as Multipath transmission is triggered, where the multipath transmission includes 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 according to claim 16, wherein: The one or more candidate relays include at least one of the following: one or more UEs different from the UE, or one or more roadside units attached to the base station.

18. The method according to 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 include at least one of the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

19. A method for a user equipment (UE), the UE being attached to a base station in a communication system, the method comprising: transmitting a relay selection request to the base station such that the relay selection request is forwarded to one or more candidate relays attached to the base station; transmitting 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 about at least one relay selected from the one or more candidate relays; as well as Multipath transmission is triggered, where the multipath transmission includes 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. The method according to claim 19, wherein The one or more candidate relays include at least one of the following: one or more UEs different from the UE, or one or more roadside units attached to the base station.

21. The method according to 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 include at least one of the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

22. A method for a relay of a user equipment (UE) in communication, the relay and the UE being attached to a base station, the method comprising: 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 state parameter indicating attachment of the relay to the base station, or (3) an availability state parameter indicating availability of the relay for multipath transmission; as well as One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

23. A method for a relay of 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 a link between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; as well as One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, the one or more measurements comprising at least one of: (1) one or more link quality parameters for a link 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, the base station comprising: a memory that stores instructions; as well as a processor configured to execute the instructions stored in the memory to: receiving one or more discovery messages communicated between a UE and one or more candidate relays, the UE and the one or more candidate relays being attached to the base station; receiving one or more measurements of one or more signals transmitted between the base station and the one or more candidate relays; determining whether the one or more candidate relays satisfy relay selection criteria based on at least one of: the one or more discovery messages, or the one or more measurements; as well as At least one relay is selected from the one or more candidate relays for multipath transmission of the UE.

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

26. The base station according to 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. The base station according to claim 24, wherein The one or more discovery messages include at least one of the following: (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 the attachment of the one or more candidate relays to the base station, or (3) one or more availability status parameters indicating the availability of the one or more candidate relays for the multipath transmission.

28. The base station according to 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 include at least one of the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

29. The base station according to claim 28, wherein The relay selection criteria include at least one of the following: (1) the one or more SL-RSRP values ​​measured for 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 for the one or more discovery messages exceed an SD-RSRP threshold.

30. The base station according to 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 indicating the availability of the one or more candidate relays for the multipath transmission.

31. The base station according to 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 the following: one or more RSRP values ​​measured for one or more signals transmitted between the base station and the one or more candidate relays, or one or more RSRQ values ​​measured for the one or more signals transmitted between the base station and the one or more candidate relays.

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

33. The base station according to claim 24, wherein The processor is further configured to execute the instructions stored in the memory to: The one or more discovery messages obtained from the one or more candidate relays are received from the UE, 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 state parameters indicating attachment of the one or more candidate relays to the base station.

34. The base station according to claim 33, wherein The processor is further configured to execute the instructions stored in the memory to: The one or more measurements are received 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 availability of the one or more candidate relays for the multipath transmission.

35. The base station according to claim 24, wherein The processor is further configured to execute the instructions stored in the memory to: The one or more discovery messages obtained from the UE are received from the one or more candidate relays, 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 base station of claim 35, wherein the processor is further configured to execute 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; and In response to the one or more relay selection requests, one or more relay selection response messages obtained from the UE are received from the one or more candidate relays.

37. The base station according to claim 35, wherein The processor is further configured to execute the instructions stored in the memory to: The one or more measurements are received from the one or more candidate relays, the one or more measurements comprising at least one of: 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.

38. The base station according to claim 24, wherein The processor is further configured to execute the instructions stored in the memory to: The selected at least one relay is transmitted to the UE to trigger 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, the UE being attached to a base station, the UE comprising: a memory that stores instructions; as well as a processor configured to execute 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, from the base station, information about at least one relay selected from the one or more candidate relays; as well as Multipath transmission is triggered, where the multipath transmission includes 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. The UE according to claim 39, wherein The one or more candidate relays include at least one of the following: one or more UEs different from the UE, or one or more roadside units attached to the base station.

41. The UE according to 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 include at least one of the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

42. A user equipment (UE) for communication, the UE being attached to a base station, the UE comprising: a memory that stores instructions; as well as a processor configured to execute the instructions stored in the memory to: transmitting a relay selection request to the base station such that the relay selection request is forwarded to one or more candidate relays attached to the base station; transmitting 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 about at least one relay selected from the one or more candidate relays; as well as Multipath transmission is triggered, where the multipath transmission includes 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. The UE according to claim 42, wherein: The one or more candidate relays include at least one of the following: one or more UEs different from the UE, or one or more roadside units attached to the base station.

44. The UE according to 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 include at least one of the following: one or more sidelink reference signal received power (SL-RSRP) values ​​measured for 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 for the one or more discovery messages.

45. A relay for a communicating user equipment (UE), the relay and the UE being attached to a base station, the relay comprising: a memory that stores instructions; as well as a processor configured to execute the instructions stored in the memory to: 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 state parameter indicating attachment of the relay to the base station, or (3) an availability state parameter indicating availability of the relay for multipath transmission; as well as One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

46. ​​A relay for a communicating user equipment (UE), the relay and the UE being attached to a base station, the relay comprising: a memory that stores instructions; as well as a processor configured to execute 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 a link between the UE and the relay; transmitting the received one or more relay selection response messages to the base station; as well as One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, the one or more measurements comprising at least one of: (1) one or more link quality parameters for a link between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission.

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

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 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, from the base station, information about at least one relay selected from the one or more candidate relays; as well as Multipath transmission is triggered, where the multipath transmission includes 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. 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 comprising: transmitting a relay selection request to a base station such that the relay selection request is forwarded to one or more candidate relays attached to the base station; transmitting 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 about at least one relay selected from the one or more candidate relays; as well as Multipath transmission is triggered, where the multipath transmission includes 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. A non-transitory computer-readable medium storing instructions executable by one or more processors of a relay for a communicating user equipment (UE) to perform a method comprising: 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 state parameter indicating attachment of the relay to the base station, or (3) an availability state parameter indicating availability of the relay for multipath transmission; as well as One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, 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 relay, or (2) an availability status parameter indicating the availability of the relay for the multipath transmission.

51. A non-transitory computer-readable medium storing instructions executable by one or more processors of a relay for a user equipment (UE) in communication to perform a 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; as well as One or more measurements of one or more signals transmitted between the base station and the relay are transmitted to the base station, the one or more measurements comprising at least one of: (1) one or more link quality parameters for a link between the base station and the relay, or (2) one or more availability status parameters indicating the availability of the relay for multipath transmission.

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