Methods and terminal devices for an enhanced discovery procedure

Abstract

The present disclosure provides a method (300) at a first terminal device. The method (300) includes the step (310) of transmitting a first message to a second terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

Description

Technology Field

[0001] The present disclosure relates to communication technology, and more specifically, to methods and terminal devices for an enhanced discovery procedure. Background Technology

[0002] 3rd Generation Partnership Project (3 rd In Generation Partnership Project (3GPP) Releases 14 and 15, Device-to-Device (D2D) communication was extended to support Vehicle-to-Everything (V2X) communication, which includes any combination of direct communication between vehicles, pedestrians, and infrastructure. V2X communication may utilize network infrastructure when available, but at least basic V2X connectivity must be possible even when network infrastructure coverage is lacking.

[0003] Figure 1 illustrates V2X scenarios using Long Term Evolution (LTE)-based network infrastructure. Providing an LTE-based V2X interface can be economically advantageous due to the economies of scale of LTE and can enable tighter integration between communications with network infrastructure (Vehicle-to-Infrastructure / Network or V2I / N), pedestrians (Vehicle-to-Pedestrian or V2P), and other vehicles (Vehicle-to-Vehicle or V2V) compared to using dedicated V2X technology (e.g., IEEE 802.11p).

[0004] V2X communications can carry non-safety and / or safety information. Applications and / or services may be associated with specific sets of requirements in terms of, for example, latency, reliability, and data rate. Several different use cases defined for V2X include the following:

[0005] - V2V: Covers LTE-based communication between vehicles via a cellular interface (known as Uu) or a sidelink interface (known as PC5);

[0006] - V2P: Covers LTE-based communication between a vehicle and a device carried by an individual (e.g., a handheld terminal carried by a pedestrian, cyclist, driver, or passenger) via Uu or Sidelink (PC5); and

[0007] - V2I / N: Covers LTE-based communication between a vehicle and an RSU (Roadside unit) or network. An RSU is a transportation infrastructure entity (e.g., an entity transmitting speed alerts) that communicates with V2X-enabled user devices (UEs) via a sidelink (PC5) or a Uu. In the case of V2N, communication is performed via a Uu.

[0008] The 3GPP System Architecture 1 (SA1) Working Group completed new service requirements for future V2X services in FS_eV2X (future study on enhancement of V2X). The SA1 Working Group identified 25 use cases for advanced V2X services to be used in 5th generation (5G) systems, namely LTE and New Radio (NR). These use cases are categorized into four use case groups: vehicles platooning, extended sensors, advanced driving, and remote driving. For some use cases, such as platooning, cooperative driving, and dynamic ride sharing, direct unicast transmission over sidelinks will be required. For these advanced applications, the expected requirements to meet the necessary data rates, capacity, reliability, latency, communication range, and speed are more stringent. The integration requirements for each use case group are captured in 3GPP Technical Report (TR) 22.886, V16.2.0.

[0009] In 3GPP Release 17, National Security and Public Safety (NSPS) is considered a significant use case that can benefit from the NR sidelink features already developed in Release 16. Therefore, 3GPP is likely to specify enhancements related to NSPS use cases that take NR Release 16 sidelinks as a baseline. Furthermore, in some scenarios, NSPS services such as indoor firefighting, wildfire suppression, earthquake rescue, and maritime rescue need to operate when network coverage is partial or even non-existent—for example, when infrastructure is (partially) destroyed or unavailable. Therefore, coverage extension is a critical enabler for NSPS services, both for those communicating between UEs and cellular networks and for those communicating between UEs via sidelinks. In Release 17, a new Study Item Description (SID) for the NR Sidelink Relay (RP-193253) was launched with the goal of further exploring coverage extensions for sidelink-based communication, including both UE-to-network relays for cellular coverage extension and UE-to-UE relays for sidelink coverage extension.

[0010] Sidelink transmissions are associated with a source Layer 1 (L1) / Layer 2 (L2) identifier (ID) and a destination L1 / L2 ID. For sidelink unicast transmissions, the source L1 / L2 ID represents the transmitter UE ID, which will become the service type and / or destination L1 / L2 ID for the peer UE. A sidelink unicast link is identified by a combination of the source L1 / L2 ID and the destination L1 / L2 ID. For sidelink groupcast transmissions, the source L1 / L2 ID represents the transmitter UE ID, and the destination L1 / L2 ID represents the group identifier provided by the upper layer or service type. For sidelink broadcast transmissions, the source L1 / L2 ID represents the transmitter UE ID, and the destination L1 / L2 ID represents the service type. The connected UE will report the destination L2 ID to its serving cell or network node.

[0011] As described in Section 6.1 of TR 23.752, V0.3.0, which is incorporated herein by reference in its entirety, the discovery procedure being studied for NR Release 17 is based on a 5G Core (5GC) architecture that includes authorization and provisioning, announcing and monitoring procedures, and discovery procedures, as described in detail in Section 6.1.2 of TR 23.752. In the Evolved Packet System (EPS), there are two types of Proximity Service (ProSe) Direct Discovery: open and restricted. Open discovery occurs when explicit permission from the UE being discovered is not required, whereas restricted discovery occurs only upon explicit permission from the UE being discovered. In addition, EPS has two models for ProSe direct discovery, namely Model A and Model B, defined in Section 5.3.1.2 of TS 23.303, V16.0.0, which is incorporated herein by reference in its entirety.

[0012] For direct discovery authorization and provisioning of a UE, an Application Function (AF) may provide group and / or service information to a Policy Control Function (PCF) via a Network Exposure Function (NEF), and the PCF may provide authorization to the UE based on the information received from the AF. The authorization and provisioning procedures in sections 6.2.2 and 6.2.5 of TS 23.287, V16.3.0 are reused to provide at least the following configurations:

[0013] 1) AF requests transmitted to the PCF (or via the NEF) include the following information:

[0014] - Service information discovered directly through the PC5 interface (service information may include, for example, an application identifier);

[0015] - Group information directly discovered through the PC5 interface (e.g., external group identifier);

[0016] - Information per announcing and monitoring direction for Model A, or per discoverer UE and discoveree UE for Model B;

[0017] - Area information, for example, geographical information (longitude / latitude, zip code, etc.).

[0018] 2) Provisioning from PCF to UE includes the following information based on local policies and information received from AF:

[0019] - Service information discovered directly through the PC5 interface (service information may include, for example, an application identifier);

[0020] - Group information directly discovered through the PC5 interface (e.g., external group identifier);

[0021] - Area information used for direct discovery via the PC5 interface (area information may be a list of Tracking Areas (TAs); the PCF is expected to map the area information provided by the AF to the list of TAs);

[0022] - Security parameters used for direct discovery via PC5.

[0023] If the Access and Mobility Management Function (AMF) determines that the UE is authorized to use direct discovery based on authorized area information, the AMF indicates to the corresponding Next Generation Radio Access Network (NG-RAN) during N2 establishment for the UE that the UE is authorized to use direct discovery through the PC5 interface.

[0024] FIG. 2 illustrates an example of a discovery procedure. In 2.0, the user may obtain a ProSe application user ID and a ProSe application code for ProSe direct discovery using application layer mechanisms. The application layer of the UE provides the application user ID and the application identifier to the ProSe application function. The ProSe application function assigns the ProSe application user ID and the ProSe application code to the application layer of the UE. In 2.1, the UE obtains authorization and provisioning to announce the discovery and / or monitor / solicitation the discovery as defined in sections 6.2.2 and 6.2.5 of TS 23.287, which are incorporated herein by reference in their entirety.

[0025] For Model A, in 2.2a, when an announcing UE is triggered by a higher-level application to announce availability for groups of interest and / or applications of interest, for example, if the UE is authorized to perform the announcing UE procedure for groups of interest and / or applications of interest in step 2.1, the UE shall generate a PC5 direct discovery message for announcement and include the following information in this message. The announcing UE calculates a security protection factor (for example, for integrity protection) and attaches it to the PC5 message:

[0026] 1) ProSe UE ID, e.g., ProSe application user ID, Layer 2 ID;

[0027] 2) Group ID(s) provided by the application layer; and

[0028] 3) Application ID(s) or ProSe application code(s) provided by the application layer.

[0029] For example, when a monitoring UE is triggered by a higher-tier application or a user to monitor the proximity of other UEs to group(s) and / or applications of interest, and when the UE is authorized to perform monitoring procedures for the group(s) and / or applications, the UE monitors discovery messages. The monitoring UE identifies security protection factors using provisioned security parameters corresponding to the application. If the identification of security protection factors is satisfactory, the service is successfully discovered by the monitoring UE. Then, the monitoring UE can use the results of the discovery to notify the application layer.

[0030] For Model B, in 2.2b, when a discoverer UE is triggered by a higher-level application or by a user to discover other UEs for group(s) and / or applications of interest, for example, and when the UE is authorized to perform a discovery solicitation procedure for group(s) and / or applications in step 2.1, the UE transmits a solicitation message using information of the discoverer ProSe UE ID, application ID(s) or ProSe application code(s), and group ID(s). The discoverer UE calculates a security protection factor (for example, for integrity protection) and attaches it to a PC5 message. If the discoveree UE can respond to the discovery solicitation based on the information received in the solicitation message and is authorized to respond, it responds to the discovery message using the discoveree ProSe UE ID, supported application ID(s) or ProSe application code(s), and group ID(s).

[0031] In 2.3a, if the monitoring UE / discoverer UE wishes to request metadata corresponding to the service discovered in step 2.2a or 2.2b, the monitoring UE / discoverer UE may send a unicast metadata request message to request discovery metadata. The monitoring UE / discoverer UE may send a metadata request message using the Layer 2 ID of the announcing UE / discovered UE (received in step 2.2a or 2.2b). In 2.3b, the announcing UE / discovered UE responds with a metadata response message. The announcing UE / discovered UE includes metadata information in the metadata response message.

[0032] It was agreed that Model A and Model B discovery procedures standardized in LTE Release 12 / Release 13 can be reused for sidelink UE-to-network and UE-to-UE relay in Release 17.

[0033] However, NR sidelinks are fundamentally different from LTE V2X. To meet the requirements for V2X and public safety scenarios, currently standardized discovery procedures need to be improved. These requirements include power saving, low latency, and reliability. Furthermore, existing discovery procedures are not optimized in terms of signaling overhead and require the UE to perform a discovery procedure whenever a new relay path needs to be selected or re-selected.

[0034] The purpose of the present disclosure is to provide terminal devices and methods therein that can solve or alleviate at least one of the above problems.

[0035] According to a first aspect of the present disclosure, a method at a first terminal device is provided. The method comprises the step of transmitting a first message to a second terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0036] In an embodiment, the first message may further include a first validity timer that indicates the duration for which information associated with the first terminal device is valid.

[0037] In an embodiment, the first application or traffic-related information may include a Quality of Service (QoS) profile of the application or traffic that the first terminal device may request or provide.

[0038] In the embodiments, the QoS profile may include the type of application or traffic, priority, and / or QoS requirements.

[0039] In an embodiment, the first location or mobility-related information may include one or more of the following: location information of the first terminal device, information about an area or proximity where the first terminal device can request or provide an application or traffic, or mobility information of the first terminal device.

[0040] In an embodiment, the mobility information of the first terminal device may indicate whether the first terminal device is static or moving.

[0041] In an embodiment, the first connectivity-related information may include a serving network node of the first terminal device, an indication of whether the first terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the first terminal device, the load or congestion status of the PC5 or Uu link, the Radio Access Technology (RAT) of the PC5 or Uu link, an indication of the type of relay that the first terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the first terminal device can request or provide.

[0042] In an embodiment, the method may further include the step of receiving a second message from a second terminal device as a response to a first message. The second message includes one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information.

[0043] In an embodiment, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device, and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0044] In an embodiment, the second application or traffic-related information may include a QoS profile of an application or traffic that the second terminal device may request or provide.

[0045] In an embodiment, the QoS profile may include the type of application or traffic that the second terminal device may request or provide, priority, and / or QoS requirements.

[0046] In an embodiment, the second location or mobility-related information may include one or more of the location information of the second terminal device, information about an area or proximity where the second terminal device can request or provide an application or traffic, or mobility information of the second terminal device.

[0047] In an embodiment, the mobility information of the second terminal device may indicate whether the second terminal device is in a stationary state or is moving.

[0048] In an embodiment, the second connectivity-related information may include a serving network node of the second terminal device, an indication of whether the second terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the second terminal device, the load or congestion status of the PC5 or Uu link, the radio access technology (RAT) of the PC5 or Uu link, an indication of the type of relay that the second terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the second terminal device can request or provide.

[0049] In an embodiment, the method may further include: obtaining a set of relay candidates including a second terminal device based on at least a second message; selecting the second terminal device as a relay between a first terminal device and a network node or a third terminal device based on second application or traffic-related information, second location or mobility-related information, and / or second connectivity-related information from the set of relay candidates; and establishing a relay path from the first terminal device to the network node or the third terminal device via the second terminal device.

[0050] In an embodiment, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid, and the selecting operation may be based on the second validity timer.

[0051] In an embodiment, the method may further include: selecting, in response to a failure of a relay path, from a set of relay candidates, a fourth terminal device as a relay between a first terminal device and a network node or a third terminal device based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device; and establishing a relay path from the first terminal device to the network node or the third terminal device via the fourth terminal device.

[0052] In an embodiment, the operation of selecting a fourth terminal may be based on a validity timer that indicates the duration for which information associated with the fourth terminal device is valid.

[0053] In an embodiment, the method may further include the step of initiating another discovery procedure through a sidelink when all relay candidates in the set have their individual validity timers expired.

[0054] In an embodiment, the first message may further include a measurement configuration for the second terminal device to measure a PC5 link toward a third terminal device or a fifth terminal device, or a Uu link toward a network node, and the second message may further include a measurement report for the PC5 link or the Uu link.

[0055] In an embodiment, the method may further include the step of receiving a measurement configuration from a network node.

[0056] In an embodiment, the method may further include the step of receiving authorization from a network node to initiate a discovery procedure.

[0057] In an embodiment, first location or mobility-related information and / or first connectivity-related information may be explicitly transmitted in one or more fields of the first message or included in a container of the first message.

[0058] In an embodiment, second location or mobility-related information and / or second connectivity-related information may be explicitly received in one or more fields of the second message or included in a container of the second message.

[0059] According to a second aspect of the present disclosure, a first terminal device is provided. The first terminal device includes a transmitting unit configured to transmit a first message to a second terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0060] The individual embodiments and features described above in relation to the first embodiment also apply to the second embodiment.

[0061] According to a third aspect of the present disclosure, a first terminal device is provided. The first terminal device includes a transceiver, a processor, and a memory. The memory includes instructions executable by the processor, thereby enabling the first terminal device to operate to perform the method according to the first aspect.

[0062] According to a fourth aspect of the present disclosure, a computer-readable storage medium is provided. The computer-readable storage medium stores computer program instructions. When the computer program instructions are executed by a processor of a first terminal device, the first terminal device causes the first terminal device to perform the method according to the first aspect.

[0063] According to a fifth aspect of the present disclosure, a method at a second terminal device is provided. The method comprises receiving a first message from a first terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0064] In an embodiment, the first application or traffic-related information may include a QoS profile of an application or traffic that the first terminal device may request or provide.

[0065] In the embodiments, the QoS profile may include the type of application or traffic, priority, and / or QoS requirements.

[0066] In an embodiment, the first location or mobility-related information may include one or more of the location information of the first terminal device, information about an area or proximity where the first terminal device can request or provide an application or traffic, or mobility information of the first terminal device.

[0067] In an embodiment, the mobility information of the first terminal device may indicate whether the first terminal device is in a stationary state or is moving.

[0068] In an embodiment, the first connectivity-related information may include a serving network node of the first terminal device, an indication of whether the first terminal device can request or provide a relay path toward the network node or the terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the first terminal device, the load or congestion status of the PC5 or Uu link, the RAT of the PC5 or Uu link, an indication of the type of relay that the first terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the first terminal device can request or provide.

[0069] In an embodiment, the method may further include: obtaining a set of relay candidates including a first terminal device based on at least a first message; selecting the first terminal device as a relay between a second terminal device and a network node or a third terminal device based on first application or traffic-related information, first location or mobility-related information, and / or first connectivity-related information from the set of relay candidates; and establishing a relay path from the second terminal device to the network node or the third terminal device via the first terminal device.

[0070] In an embodiment, the first message may further include a first validity timer indicating the duration for which information associated with the first terminal device is valid, and the selecting operation may be based on the first validity timer.

[0071] In an embodiment, the method may further include: selecting, in response to a failure of a relay path, from a set of relay candidates, a fourth terminal device as a relay between a second terminal device and a network node or a third terminal device based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device; and establishing a relay path from the second terminal device to the network node or the third terminal device via the fourth terminal device.

[0072] In an embodiment, the operation of selecting a fourth terminal may be based on a validity timer that indicates the duration for which information associated with the fourth terminal device is valid.

[0073] In an embodiment, the method may further include the step of initiating another discovery procedure through a sidelink when all relay candidates in the set have their individual validity timers expired.

[0074] In an embodiment, the method may further include the step of transmitting a second message to a first terminal device as a response to a first message. The second message may include one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information.

[0075] In an embodiment, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid.

[0076] In an embodiment, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device, and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0077] In an embodiment, the second application or traffic-related information may include a QoS profile of an application or traffic that the second terminal device may request or provide.

[0078] In an embodiment, the QoS profile may include the type of application or traffic that the second terminal device may request or provide, priority, and / or QoS requirements.

[0079] In an embodiment, the second location or mobility-related information may include one or more of the location information of the second terminal device, information about an area or proximity where the second terminal device can request or provide an application or traffic, or mobility information of the second terminal device.

[0080] In an embodiment, the mobility information of the second terminal device may indicate whether the second terminal device is in a stationary state or is moving.

[0081] In an embodiment, the second connectivity-related information may include a serving network node of the second terminal device, an indication of whether the second terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the second terminal device, the load or congestion status of the PC5 or Uu link, the RAT of the PC5 or Uu link, an indication of the type of relay that the second terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the second terminal device can request or provide.

[0082] In an embodiment, the first message may further include a measurement configuration for the second terminal device to measure a PC5 link toward a third terminal device or a fifth terminal device, or a Uu link toward a network node, and the second message may further include a measurement report for the PC5 link or the Uu link.

[0083] In an embodiment, the method may further include the step of receiving a measurement configuration from a network node.

[0084] In an embodiment, the method may further include the step of receiving authorization from a network node to engage in a discovery procedure.

[0085] In an embodiment, first location or mobility-related information and / or first connectivity-related information may be explicitly received in one or more fields of the first message or included in a container of the first message.

[0086] In an embodiment, second location or mobility-related information and / or second connectivity-related information may be explicitly transmitted in one or more fields of the second message or included in a container of the second message.

[0087] According to a sixth aspect of the present disclosure, a second terminal device is provided. The second terminal device includes a receiving unit configured to receive a first message from a first terminal device for initiating a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0088] The individual embodiments and features described above in relation to the fifth embodiment also apply to the sixth embodiment.

[0089] According to a seventh aspect of the present disclosure, a second terminal device is provided. The second terminal device includes a transceiver, a processor, and a memory. The memory includes instructions executable by the processor, thereby enabling the second terminal device to operate to perform a method according to a fifth aspect.

[0090] According to the eighth aspect of the present disclosure, a computer-readable storage medium is provided. The computer-readable storage medium stores computer program instructions. When the computer program instructions are executed by a processor of a second terminal device, the second terminal device causes the second terminal device to perform the method according to the fifth aspect.

[0091] According to a ninth aspect of the present disclosure, a method at a network node is provided. The method comprises: transmitting to a terminal device an authorization to initiate a discovery procedure or to participate in a discovery procedure; and transmitting to the terminal device a measurement configuration for the terminal device to measure a PC5 link or a Uu link toward a network node or another terminal device.

[0092] In an embodiment, the authorization and / or measurement configuration may be transmitted via System Information Block (SIB) or Radio Resource Control (RRC) signaling.

[0093] According to the tenth aspect of the present disclosure, a network node is provided. The network device comprises: transmitting to a terminal device an authorization to initiate a discovery procedure or to participate in a discovery procedure; and transmitting to the terminal device a measurement configuration for the terminal device to measure a PC5 link or a Uu link toward the network node or another terminal device.

[0094] The individual embodiments and features described above in relation to the ninth aspect also apply to the tenth aspect.

[0095] According to the first aspect of the present disclosure, a network node is provided. The network node comprises a transceiver, a processor, and a memory. The memory comprises instructions executable by the processor, thereby enabling the network node to operate to perform the method according to the ninth aspect.

[0096] According to a 12th aspect of the present disclosure, a computer-readable storage medium is provided. The computer-readable storage medium stores computer program instructions. When the computer program instructions are executed by a processor of a network node, the network node causes the network node to perform the method according to the 9th aspect.

[0097] According to embodiments of the present disclosure, one or more messages of a discovery procedure may be enhanced by additional information. For example, a message for initiating a discovery procedure via a sidelink may include application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the terminal device transmitting the message. By such information, the efficiency of the discovery procedure for establishing a UE-to-network or UE-to-UE relay path may be improved. Brief explanation of the drawing

[0098] The above and other purposes, features, and advantages will become more apparent from the following description of embodiments with reference to the drawings. Figure 1 is a schematic diagram illustrating V2X scenarios using LTE-based network infrastructure. Figure 2 is a schematic diagram illustrating an example of a discovery procedure. FIG. 3 is a flowchart illustrating a method in a first terminal device according to an embodiment of the present disclosure. FIG. 4 is a flowchart illustrating a method in a second terminal device according to an embodiment of the present disclosure. FIG. 5 is a flowchart illustrating a method at a network node according to an embodiment of the present disclosure. FIG. 6 is a block diagram of a first terminal device according to an embodiment of the present disclosure. FIG. 7 is a block diagram of a first terminal device according to another embodiment of the present disclosure. FIG. 8 is a block diagram of a second terminal device according to an embodiment of the present disclosure. FIG. 9 is a block diagram of a second terminal device according to another embodiment of the present disclosure. FIG. 10 is a block diagram of a network node according to an embodiment of the present disclosure. FIG. 11 is a block diagram of a network node according to another embodiment of the present disclosure. Figure 12 schematically illustrates a telecommunications network connected to a host computer via an intermediate network. FIG. 13 is a generalized block diagram of a host computer communicating with user equipment via a base station through a partial wireless connection. FIGS. 14 through 17 are flowcharts illustrating methods implemented in a communication system including a host computer, a base station, and user equipment. Specific details for implementing the invention

[0099] As used herein, the term “wireless communication network” refers to a network conforming to any suitable communication standard such as NR, LTE-A (LTE-Advanced), LTE, WCDMA (Wideband Code Division Multiple Access), HSPA (High-Speed ​​Packet Access), etc. Additionally, communications between a terminal device and a network node of a wireless communication network include, but are not limited to, any suitable generation of communication protocols including, but not limited to, GSM (Global System for Mobile Communications), UMTS (Universal Mobile Telecommunications System), LTE (Long Term Evolution), and / or other suitable 1G (Generation 1), 2G (Generation 2), 2.5G, 2.75G, 3G (Generation 3), 4G (Generation 4), 4.5G, and 5G (Generation 5) communication protocols, wireless local area network (WLAN) standards, such as IEEE 802.11 standards; and / or may be carried out according to any other suitable wireless communication standards, such as WiMAX (Worldwide Interoperability for Microwave Access), Bluetooth, and / or ZigBee standards, and / or any other protocols currently known or to be developed in the future.

[0100] The terms “network node” or “network device” refer to a device in a wireless communication network to which a terminal device accesses the network and receives services from it. A network node or network node refers to a base station (BS), an access point (AP), or any other suitable device in a wireless communication network. A BS may be, for example, a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), or a (next) generation (gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low-power node, such as a femto, pico, etc. Other examples of network nodes may include multi-standard radio (MSR) equipment, such as MSR BSs, network controllers, such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmitting points, and transmitting nodes. However, more generally, a network node may represent any suitable device (or group of devices) configured, arranged, and / or operable to enable and / or provide terminal device access to a wireless communication network or to provide some services to a terminal device accessing the wireless communication network.

[0101] The term "terminal device" refers to any end device capable of accessing a wireless communication network and receiving services therefrom. By example, but not by limitation, a terminal device refers to a mobile terminal, user equipment (UE), or other appropriate device. A UE may be, for example, a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). Terminal devices may include, but are not limited to, portable computers, desktop computers, image capture terminal devices, such as digital cameras, game terminal devices, music storage and playback devices, mobile phones, cellular phones, smartphones, VoIP (voice over IP) phones, wireless local loop phones, tablets, PDAs (personal digital assistants), wearable terminal devices, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, LEE (laptop-embedded equipment), LME (laptop-mounted equipment), USB dongles, smart devices, wireless CPE (customer-premises equipment), etc. In the following description, the terms "terminal device," "terminal," "user equipment," and "UE" may be used interchangeably. As an example, a terminal device may represent a UE configured for communication according to one or more communication standards published by the 3rd Generation Partnership Project (3GPP), such as 3GPP's GSM, UMTS, LTE, and / or 5G standards.As used herein, "user equipment" or "UE" may not necessarily have a "user" in the sense of a human user who owns and / or operates the relevant device. In some embodiments, the terminal device may be configured to transmit and / or receive information without direct human interaction. For example, the terminal device may be designed to transmit information to a network on a predetermined schedule when triggered by an internal or external event, or in response to requests from a wireless communication network. Instead, the UE may represent a device intended for sale to a human user or for operation by a human user, but which may not initially be associated with a specific human user.

[0102] A terminal device can support device-to-device (D2D) communication by implementing, for example, 3GPP standards for sidelink communication, and in this case, it may be referred to as a D2D communication device.

[0103] As another example, in an Internet of Things (IoT) scenario, a terminal device may represent a machine or other device that performs monitoring and / or measurements and transmits the results of such monitoring and / or measurements to other terminal devices and / or network equipment. In this case, the terminal device may be a machine-to-machine (M2M) device, which may be referred to as a machine-type communication (MTC) device in the context of 3GPP. As one specific example, the terminal device may be a UE implementing the 3GPP narrow band Internet of Things (NB-IoT) standard. Specific examples of such machines or devices include sensors, metering devices, such as power meters, industrial machinery, or household or personal devices, such as refrigerators, televisions, and personal wearables, such as watches. In other scenarios, the terminal device may represent a vehicle or other equipment capable of monitoring its operating status or other functions associated with its operation and / or reporting thereon.

[0104] As used herein, downlink transmission refers to transmission from a network node to a terminal device, and uplink transmission refers to transmission in the opposite direction.

[0105] References to "one embodiment," "an embodiment," "an exemplary embodiment," etc., in the specification indicate that while the described embodiment may include a specific feature, structure, or characteristic, not all embodiments are required to include that specific feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, or characteristic is described in relation to an embodiment, it is suggested that the influence of such feature, structure, or characteristic in relation to other embodiments, whether explicitly described or not, is within the knowledge of a person skilled in the art.

[0106] It should be understood that while terms such as “first” and “second” may be used in this specification to describe various elements, these elements should not be limited by these terms. These terms are used solely to distinguish one element from another. For example, without departing from the scope of exemplary embodiments, the first element may be named the second element, and similarly, the second element may be named the first element. As used in this specification, the term “and / or” includes any one or more of the associated enumerated terms and all combinations thereof. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit exemplary embodiments. As used in this specification, singular forms (“a,” “an,” and “the”) are intended to include plural forms unless the context clearly indicates otherwise. It will be further understood that as used herein, the terms “comprises,” “comprising,” “has,” “having,” “includes,” and / or “including” specify the existence of the mentioned features, elements, and / or components, but do not exclude the existence or addition of one or more other features, elements, components, and / or combinations thereof.

[0107] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by a person skilled in the art to which this disclosure pertains.

[0108] FIG. 3 is a flowchart illustrating a method (300) according to an embodiment of the present disclosure. The method (300) may be performed at a first terminal device, which may be an announcing UE of Model A or a discoverer UE of Model B. The first terminal device may initiate a discovery procedure with a second terminal device via a side link (or PC5 interface) to establish communication between the first terminal device and the second terminal device. The side link or PC5 communication may serve as a segment of a relay path between a remote UE (hereinafter referred to as "RM UE") and another entity (which may be a network node in the case of a UE-to-network relay, or another UE in the case of a UE-to-UE relay) via a relay UE (hereinafter referred to as "RL UE"). In this case, the first terminal device may be an RM UE and the second terminal device may be an RL UE, or alternatively, the first terminal device may be an RL UE and the second terminal device may be an RM UE.

[0109] In block (310), the first terminal device transmits a first message to the second terminal device to initiate a discovery procedure via a sidelink. Here, the first message may be, for example, the discovery message in 2.2a of FIG. 2, or the discovery invitation in 2.2b of FIG. 2. In the example, prior to block (310), the first terminal device may receive authorization to initiate a discovery procedure from a network node, for example, its serving gNB.

[0110] The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information. Additionally, the first message may include, as described above, 1) a ProSe UE ID, e.g., a ProSe application user ID, a Layer 2 ID; 2) group ID(s) provided by the application layer; and 3) application ID(s) or ProSe application code(s) provided by the application layer.

[0111] In the example, the first message may further include a first validity timer indicating the duration for which information associated with the first terminal device is valid.

[0112] In the example, the first application or traffic-related information may include a QoS profile of the application or traffic that the first terminal device may request or provide. Here, the QoS profile may include the type, priority, and / or QoS requirements of the application or traffic.

[0113] In the example, the first location or mobility-related information may include one or more of the location information of the first terminal device (e.g., Global Positioning System (GPS) coordinates), information about the area or proximity where the first terminal device may request or provide an application or traffic, or mobility information of the first terminal device. Here, the mobility information of the first terminal device may indicate whether the first terminal device is stationary or moving, and / or the type of mobility, e.g., pedestrian or vehicle.

[0114] In the example, the first connectivity-related information is,

[0115] Serving network node of the first terminal device,

[0116] An indication of whether the first terminal device can request or provide a relay path toward a network node or peer terminal device (e.g., ID of the network node or peer terminal device),

[0117] A list of terminal device IDs obtained in the previous discovery procedure,

[0118] Radio quality indication of the PC5 or Uu link currently possessed by the first terminal device,

[0119] Load or congestion status of PC5 or Uu link,

[0120] PC5 or Uu link RAT (e.g., LTE or NR),

[0121] An indication of the type of relay (e.g., UE-to-Network or UE-to-UE) that the first terminal device may request or provide, or

[0122] The number of hops along a relay path or the maximum number of hops that the first terminal device can request or provide

[0123] It may include one or more of the following.

[0124] Here, any of the above IDs may be a temporary ID used only for the discovery procedure, and becomes invalid when the discovery procedure is completed.

[0125] In the example, the Access Stratum (AS) configuration / information of the first message, e.g., first location or mobility-related information and / or first connectivity-related information, may be explicitly transmitted in one or more fields of the first message or may be included in a container of the first message (e.g., OCTET STRING). The container may function, for example, as a pointer to a part of the RRC specification to which the AS configuration / information is standardized.

[0126] In the example, the first terminal device may receive a second message from the second terminal device as a response to the first message. Here, the second message may be, for example, a response to the discovery message in 2.2a of FIG. 2 (not shown), or the discovery message in 2.2b of FIG. 2.

[0127] The second message includes one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information.

[0128] In the example, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device (e.g., used only for the discovery procedure), and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0129] In the example, the second application or traffic-related information may include a QoS profile of the application or traffic that the second terminal device may request or provide. Here, the QoS profile may include the type, priority, and / or QoS requirements of the application or traffic that the second terminal device may request or provide.

[0130] In the example, the second location or mobility-related information may include one or more of the following: location information of the second terminal device (e.g., GPS coordinates), information about an area or proximity where the second terminal device may request or provide an application or traffic, or mobility information of the second terminal device. Here, the mobility information of the second terminal device may indicate whether the second terminal device is stationary or moving, and / or the type of mobility, e.g., pedestrian or vehicle.

[0131] In the example, the second connectivity-related information is,

[0132] Serving network node of the second terminal device,

[0133] Indication of whether the second terminal device can request or provide a relay path toward a network node or peer terminal device (e.g., ID of the network node or peer terminal device),

[0134] A list of terminal device IDs obtained in the previous discovery procedure,

[0135] Radio quality indication of the PC5 or Uu link currently possessed by the second terminal device,

[0136] Load or congestion status of PC5 or Uu link,

[0137] PC5 or Uu link RAT (e.g., LTE or NR),

[0138] An indication of the type of relay (e.g., UE-to-Network or UE-to-UE) that the second terminal device may request or provide, or

[0139] The number of hops along the relay path or the maximum number of hops that the second terminal device can request or provide

[0140] It may include.

[0141] In the example, the AS configuration / information of the second message, e.g., second location or mobility-related information and / or second connectivity-related information, may be explicitly received in one or more fields of the second message or may be included in a container of the second message (e.g., OCTET STRING). The container may function, for example, as a pointer to a part of the RRC specification to which the AS configuration / information is standardized.

[0142] In an example where the first terminal device operates as an RM UE, it may obtain a set of relay candidates including the second terminal device based at least on the second message. For example, the first terminal device may obtain a set of relay candidates by receiving a message similar to the second message from each of the relay candidates. Next, the first terminal device may select the second terminal device as a relay (RL UE) between the first terminal device and a network node or peer terminal device (e.g., referred to as the third terminal device) from the set of relay candidates based on second application or traffic-related information, second location or mobility-related information, and / or second connectivity-related information. Here, the first terminal device may sort the relay candidates within the set according to specific criteria and select the "best" relay candidate as the RL UE. For example, the first terminal device, as an RL UE, can select a relay candidate capable of providing a specific application or traffic of interest at a desired QoS in a specific area (e.g., a relay candidate connected to a network node or peer terminal device capable of providing a specific application or traffic at a desired QoS in a specific area). The first terminal device can prioritize a relay candidate capable of providing a UE-to-network relay over a relay candidate capable of providing a UE-to-UE relay. The first terminal device can prioritize a relay candidate having a PC5 or Uu link with better radio quality and / or lower load over a relay candidate having a PC5 or Uu link with worse radio quality and / or higher load. The first terminal device can prioritize a relay candidate having an NR PC5 or Uu link over a relay candidate having an LTE PC5 or Uu link.Then, the first terminal device can establish a relay path from the first terminal device to a network node or a third terminal device via a (selected) second terminal device.

[0143] In the example, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid. The second terminal device may be selected as an RL UE based on the second validity timer only when, for example, the second validity timer has not expired.

[0144] When the above establishment of the relay path is successful, the discovery procedure is terminated, and the first terminal device can clear the set of relay candidates from its memory. Alternatively, the first terminal device may maintain the set of relay candidates and remove a relay candidate from the set only when its associated validity timer expires, or the first terminal device may maintain the set of relay candidates until a new discovery procedure is triggered.

[0145] When the establishment of the relay path fails, the first terminal device may select another (e.g., a second best) relay candidate from the set as an RL UE, and, provided its associated validity timer has not expired, establish a relay path from the first terminal device to a network node or a third terminal device via the newly selected RL UE. When the establishment fails again, the first terminal device may try another relay candidate. If all relay candidates in the set have been tried but the establishment continues to fail, a new discovery procedure may be initiated.

[0146] For example, when an established relay path fails due to, for example, a degradation of link quality between a first terminal device (RM UE) and an RL UE, the first terminal device may, in response to the failure of the relay path, select from a set of relay candidates another terminal device (e.g., referred to as a fourth terminal device) as a relay (RL UE) between the first terminal device and a network node or a third terminal device, based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device. For example, the fourth terminal device may be selected based on a validity timer indicating the duration for which information associated with the fourth terminal device is valid, for example, when the validity timer has not expired. Then, the first terminal device may establish a relay path from the first terminal device to the network node or the third terminal device via the fourth terminal device.

[0147] In the example, the first terminal device can initiate another discovery procedure through a sidelink when all relay candidates in the set have their individual validity timers expired.

[0148] In an example where the first terminal device operates as an RM UE, the first message may further include a measurement configuration for the second terminal device (which is a relay candidate) to measure a PC5 link toward a peer terminal device (e.g., the third terminal device or another terminal device) or a Uu link toward a network node. The measurement configuration may include, for example, time-frequency resources to be measured and / or quantities to be measured (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or Signal to Interference plus Noise Ratio (SINR)). The first terminal device may receive the measurement configuration from a network node, for example, its serving gNB, via SIB or dedicated RRC signaling when it is within coverage. The second message may further include a measurement report for the PC5 link or Uu link, including quantities measured by the second terminal device according to the measurement report.

[0149] FIG. 4 is a flowchart illustrating a method (400) according to an embodiment of the present disclosure. The method (400) may be performed at a second terminal device, which may be a monitoring UE of Model A or a discoverer UE of Model B. The second terminal device may establish communication between the first terminal device and the second terminal device in response to a discovery procedure initiated by the first terminal device via a side link (or PC5 interface). The side link or PC5 communication may serve as a segment of a relay path between an RM UE and another entity (which may be a network node in the case of a UE-to-network relay, or another UE in the case of a UE-to-UE relay) via an RL UE. In this case, the first terminal device may be an RM UE and the second terminal device may be an RL UE, or alternatively, the first terminal device may be an RL UE and the second terminal device may be an RM UE.

[0150] In block (410), the second terminal device receives a first message from the first terminal device to initiate a discovery procedure via a side link. Here, the first message may be, for example, the discovery message in 2.2a of FIG. 2, or the discovery invitation in 2.2b of FIG. 2.

[0151] The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information. Additionally, the first message may include, as described above, 1) a ProSe UE ID, e.g., a ProSe application user ID, a Layer 2 ID; 2) group ID(s) provided by the application layer; and 3) application ID(s) or ProSe application code(s) provided by the application layer.

[0152] In the example, the first application or traffic-related information may include a QoS profile of the application or traffic that the first terminal device may request or provide. Here, the QoS profile may include the type, priority, and / or QoS requirements of the application or traffic.

[0153] In the example, the first location or mobility-related information may include one or more of the location information of the first terminal device (e.g., GPS coordinates), information about an area or proximity where the first terminal device may request or provide an application or traffic, or mobility information of the first terminal device. Here, the mobility information of the first terminal device may indicate whether the first terminal device is stationary or moving, and / or the type of mobility, e.g., pedestrian or vehicle.

[0154] In the example, the first connectivity-related information is,

[0155] Serving network node of the first terminal device,

[0156] An indication of whether the first terminal device can request or provide a relay path toward a network node or peer terminal device (e.g., ID of the network node or peer terminal device),

[0157] A list of terminal device IDs obtained in the previous discovery procedure,

[0158] Radio quality indication of the PC5 or Uu link currently possessed by the first terminal device,

[0159] Load or congestion status of PC5 or Uu link,

[0160] PC5 or Uu link RAT (e.g., LTE or NR),

[0161] An indication of the type of relay (e.g., UE-to-Network or UE-to-UE) that the first terminal device may request or provide, or

[0162] The number of hops along a relay path or the maximum number of hops that the first terminal device can request or provide

[0163] It may include one or more of the following.

[0164] Here, any of the above IDs may be a temporary ID used only for the discovery procedure, and it becomes invalid once the discovery procedure is completed.

[0165] In the example, the AS configuration / information of the first message, e.g., first location or mobility-related information and / or first connectivity-related information, may be explicitly received in one or more fields of the first message or may be included in a container of the first message (e.g., OCTET STRING). The container may function, for example, as a pointer to a part of the RRC specification to which the AS configuration / information is standardized.

[0166] In an example where the second terminal device operates as an RM UE, it may obtain a set of relay candidates including the first terminal device based on at least a first message. For example, the second terminal device may obtain a set of relay candidates by receiving a message similar to the first message from each of the relay candidates. Next, the second terminal device may select the first terminal device as a relay (RL UE) between the second terminal device and a network node or peer terminal device (e.g., referred to as the third terminal device) from the set of relay candidates based on first application or traffic-related information, first location or mobility-related information, and / or first connectivity-related information. Here, the second terminal device may sort the relay candidates within the set according to specific criteria and select the "best" relay candidate as the RL UE. For example, the second terminal device, as an RL UE, can select a relay candidate capable of providing a specific application or traffic of interest at a desired QoS in a specific area (e.g., a relay candidate connected to a network node or peer terminal device capable of providing a specific application or traffic at a desired QoS in a specific area). The second terminal device can prioritize a relay candidate capable of providing a UE-to-network relay over a relay candidate capable of providing a UE-to-UE relay. The second terminal device can prioritize a relay candidate with a PC5 or Uu link having better radio quality and / or lower load over a relay candidate with a PC5 or Uu link having worse radio quality and / or higher load. The second terminal device can prioritize a relay candidate with an NR PC5 or Uu link over a relay candidate with an LTE PC5 or Uu link.Then, the second terminal device can establish a relay path from the second terminal device to a network node or a third terminal device via the (selected) first terminal device.

[0167] In the example, the first message may further include a first validity timer indicating the duration for which information associated with the first terminal device is valid. The first terminal device may be selected as an RL UE based on a second validity timer only when, for example, the first validity timer has not expired.

[0168] When the above establishment of the relay path is successful, the discovery procedure is terminated, and the second terminal device can clear the set of relay candidates from its memory. Alternatively, the second terminal device may maintain the set of relay candidates and remove a relay candidate from the set only when its associated validity timer expires, or the second terminal device may maintain the set of relay candidates until a new discovery procedure is triggered.

[0169] When the establishment of the relay path fails, the second terminal device may select another (e.g., a second best) relay candidate from the set as an RL UE, and, provided its associated validity timer has not expired, establish a relay path from the second terminal device to a network node or a third terminal device via the newly selected RL UE. When the establishment fails again, the second terminal device may try another relay candidate. If all relay candidates in the set have been tried but the establishment continues to fail, a new discovery procedure may be initiated.

[0170] For example, when an established relay path fails due to, for example, a deterioration in link quality between a second terminal device (RM UE) and an RL UE, the second terminal device may, in response to the failure of the relay path, select from a set of relay candidates another terminal device (e.g., referred to as a fourth terminal device) as a relay (RL UE) between the second terminal device and a network node or a third terminal device, based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device. For example, the fourth terminal device may be selected based on a validity timer indicating the duration for which information associated with the fourth terminal device is valid, for example, when the validity timer has not expired. Then, the second terminal device may establish a relay path from the second terminal device to the network node or the third terminal device via the fourth terminal device.

[0171] In the example, the second terminal device can initiate another discovery procedure through the sidelink when all relay candidates in the set have their individual validity timers expired.

[0172] In the example, the second terminal device may transmit a second message to the first terminal device as a response to the first message. Here, the second message may be, for example, a response to the discovery message in 2.2a of FIG. 2 (not shown), or the discovery message in 2.2b of FIG. 2.

[0173] The second message includes one or more of the following information associated with the second terminal device: identifier information, information related to the second application or traffic, information related to the second location or mobility, or information related to the second connectivity. In the example, before transmitting the second message, the second terminal device may receive authorization to engage in a discovery procedure from a network node, e.g., its serving gNB (e.g., by responding to the first message).

[0174] In the example, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid.

[0175] In the example, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device (e.g., used only for the discovery procedure), and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0176] In the example, the second application or traffic-related information may include a QoS profile of the application or traffic that the second terminal device may request or provide. Here, the QoS profile may include the type, priority, and / or QoS requirements of the application or traffic that the second terminal device may request or provide.

[0177] In the example, the second location or mobility-related information may include one or more of the following: location information of the second terminal device (e.g., GPS coordinates), information about an area or proximity where the second terminal device may request or provide an application or traffic, or mobility information of the second terminal device. Here, the mobility information of the second terminal device may indicate whether the second terminal device is stationary or moving, and / or the type of mobility, e.g., pedestrian or vehicle.

[0178] In the example, the second connectivity-related information is,

[0179] Serving network node of the second terminal device,

[0180] Indication of whether the second terminal device can request or provide a relay path toward a network node or peer terminal device (e.g., ID of the network node or peer terminal device),

[0181] A list of terminal device IDs obtained in the previous discovery procedure,

[0182] Radio quality indication of the PC5 or Uu link currently possessed by the second terminal device,

[0183] Load or congestion status of PC5 or Uu link,

[0184] PC5 or Uu link RAT (e.g., LTE or NR),

[0185] An indication of the type of relay (e.g., UE-to-Network or UE-to-UE) that the second terminal device may request or provide, or

[0186] The number of hops along the relay path or the maximum number of hops that the second terminal device can request or provide

[0187] It may include.

[0188] In the example, the AS configuration / information of the second message, e.g., second location or mobility-related information and / or second connectivity-related information, may be explicitly transmitted in one or more fields of the second message or may be included in a container of the second message (e.g., OCTET STRING). The container may function, for example, as a pointer to a part of the RRC specification to which the AS configuration / information is standardized.

[0189] In an example where the first terminal device operates as an RM UE, the first message may further include a measurement configuration for the second terminal device (which is a relay candidate) to measure a PC5 link toward a peer terminal device (e.g., the third terminal device or another terminal device) or a Uu link toward a network node. The measurement configuration may include, for example, time-frequency resources to be measured and / or quantities to be measured (e.g., RSRP, RSRQ, or SINR). The second terminal device may also receive a measurement configuration from a network node, for example, its serving gNB, via SIB or dedicated RRC signaling. The second terminal device may perform measurements on the PC5 link or Uu link using the measurement configuration from the first terminal device, or using the measurement configuration from the network node, or using a predefined measurement configuration. The second message may further include a measurement report on the PC5 link or Uu link, which includes quantities measured by the second terminal device according to the measurement report.

[0190] FIG. 5 is a flowchart illustrating a method (500) according to an embodiment of the present disclosure. The method (500) may be performed at a network node, for example, at a serving network node of the first or second terminal device.

[0191] In block (510), the network node transmits authorization to a terminal device (e.g., the first or second terminal device) to initiate a discovery procedure or to participate in a discovery procedure.

[0192] In block (520), the network node transmits to the terminal device a measurement configuration for the terminal device to measure the PC5 link or Uu link toward the network node or another (peer) terminal device.

[0193] In the example, authorization and / or measurement configurations can be transmitted via SIB or (dedicated) RRC signaling.

[0194] Corresponding to the method (300) described above, a first terminal device is provided. FIG. 6 is a block diagram of a first terminal device (600) according to an embodiment of the present disclosure. The first terminal device (600) may be, for example, an announcing UE of Model A or a discoverer UE of Model B. The first terminal device (600) may function as an RM UE or an RL UE.

[0195] The first terminal device (600) may be configured to perform the method (300) as described above in relation to FIG. 3. As illustrated in FIG. 6, the first terminal device (600) includes a transmitting unit (610) configured to transmit a first message to a second terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0196] In an embodiment, the first message may further include a first validity timer indicating the duration for which information associated with the first terminal device is valid.

[0197] In an embodiment, the first application or traffic-related information may include a Quality of Service (QoS) profile of the application or traffic that the first terminal device may request or provide.

[0198] In the embodiments, the QoS profile may include the type of application or traffic, priority, and / or QoS requirements.

[0199] In an embodiment, the first location or mobility-related information may include one or more of the location information of the first terminal device, information about an area or proximity where the first terminal device can request or provide an application or traffic, or mobility information of the first terminal device.

[0200] In an embodiment, the mobility information of the first terminal device may indicate whether the first terminal device is in a stationary state or is moving.

[0201] In an embodiment, the first connectivity-related information may include a serving network node of the first terminal device, an indication of whether the first terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the first terminal device, the load or congestion status of the PC5 or Uu link, the radio access technology (RAT) of the PC5 or Uu link, an indication of the type of relay that the first terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the first terminal device can request or provide.

[0202] In an embodiment, the first terminal device (600) may further include a receiving unit configured to receive a second message from the second terminal device as a response to a first message. The second message includes one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information.

[0203] In an embodiment, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device, and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0204] In an embodiment, the second application or traffic-related information may include a QoS profile of an application or traffic that the second terminal device may request or provide.

[0205] In an embodiment, the QoS profile may include the type of application or traffic that the second terminal device may request or provide, priority, and / or QoS requirements.

[0206] In an embodiment, the second location or mobility-related information may include one or more of the location information of the second terminal device, information about an area or proximity where the second terminal device can request or provide an application or traffic, or mobility information of the second terminal device.

[0207] In an embodiment, the mobility information of the second terminal device may indicate whether the second terminal device is in a stationary state or is moving.

[0208] In an embodiment, the second connectivity-related information may include a serving network node of the second terminal device, an indication of whether the second terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the second terminal device, the load or congestion status of the PC5 or Uu link, the radio access technology (RAT) of the PC5 or Uu link, an indication of the type of relay that the second terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the second terminal device can request or provide.

[0209] In an embodiment, the first terminal device (600) may further include: an acquisition unit configured to acquire a set of relay candidates including a second terminal device based on at least a second message; a selection unit configured to select the second terminal device as a relay between the first terminal device and a network node or a third terminal device based on second application or traffic-related information, second location or mobility-related information, and / or second connectivity-related information from the set of relay candidates; and an establishment unit configured to establish a relay path from the first terminal device to the network node or a third terminal device via the second terminal device.

[0210] In an embodiment, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid, and the second terminal device may be selected based on the second validity timer.

[0211] In an embodiment, the selection unit may be further configured to select, in response to a failure of the relay path, from a set of relay candidates, the fourth terminal device as a relay between the first terminal device and the network node or the third terminal device based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device. The establishment unit may be further configured to establish a relay path from the first terminal device to the network node or the third terminal device via the fourth terminal device.

[0212] In an embodiment, the fourth terminal may be selected based on a validity timer that indicates the duration for which information associated with the fourth terminal device is valid.

[0213] In an embodiment, the first terminal device (600) may further include an initiation unit configured to initiate another discovery procedure via a side link when all relay candidates of the set have their individual validity timers expired.

[0214] In an embodiment, the first message may further include a measurement configuration for the second terminal device to measure a PC5 link toward a third terminal device or a fifth terminal device, or a Uu link toward a network node, and the second message may further include a measurement report for the PC5 link or the Uu link.

[0215] In an embodiment, the first terminal device (600) may further include a receiving unit configured to receive a measurement configuration from a network node.

[0216] In an embodiment, the first terminal device (600) may further include a receiving unit configured to receive authorization to initiate a discovery procedure from a network node.

[0217] In an embodiment, first location or mobility-related information and / or first connectivity-related information may be explicitly transmitted in one or more fields of the first message or included in a container of the first message.

[0218] In an embodiment, second location or mobility-related information and / or second connectivity-related information may be explicitly received in one or more fields of the second message or included in a container of the second message.

[0219] The unit (610) may be implemented as a pure hardware solution or as a combination of software and hardware, for example, by a processor or microprocessor and suitable software and memory for storing software, a Programmable Logic Device (PLD), or one or more of other electronic components or processing circuits configured to perform the actions described above, for example, illustrated in FIG. 3.

[0220] FIG. 7 is a block diagram of a first terminal device (700) according to another embodiment of the present disclosure. The first terminal device (700) may be, for example, an announcing UE of Model A or a discoverer UE of Model B. The first terminal device (700) may function as an RM UE or an RL UE.

[0221] The first terminal device (700) includes a transceiver (710), a processor (720), and a memory (730). The memory (730) includes instructions executable by the processor (720), thereby enabling the first terminal device (700) to operate to perform actions of the procedure described above, for example, in relation to FIG. 3. In particular, the memory (730) may include instructions executable by the processor (720), thereby enabling the first terminal device (700) to operate to transmit a first message to the second terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0222] In an embodiment, the first message may further include a first validity timer indicating the duration for which information associated with the first terminal device is valid.

[0223] In an embodiment, the first application or traffic-related information may include a Quality of Service (QoS) profile of the application or traffic that the first terminal device may request or provide.

[0224] In the embodiments, the QoS profile may include the type of application or traffic, priority, and / or QoS requirements.

[0225] In an embodiment, the first location or mobility-related information may include one or more of the location information of the first terminal device, information about an area or proximity where the first terminal device can request or provide an application or traffic, or mobility information of the first terminal device.

[0226] In an embodiment, the mobility information of the first terminal device may indicate whether the first terminal device is in a stationary state or is moving.

[0227] In an embodiment, the first connectivity-related information may include a serving network node of the first terminal device, an indication of whether the first terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the first terminal device, the load or congestion status of the PC5 or Uu link, the radio access technology (RAT) of the PC5 or Uu link, an indication of the type of relay that the first terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the first terminal device can request or provide.

[0228] In an embodiment, the memory (730) may further include instructions executable by the processor (720), thereby enabling the first terminal device (700) to operate to receive a second message from the second terminal device as a response to a first message. The second message includes one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information.

[0229] In an embodiment, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device, and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0230] In an embodiment, the second application or traffic-related information may include a QoS profile of an application or traffic that the second terminal device may request or provide.

[0231] In an embodiment, the QoS profile may include the type of application or traffic that the second terminal device may request or provide, priority, and / or QoS requirements.

[0232] In an embodiment, the second location or mobility-related information may include one or more of the location information of the second terminal device, information about an area or proximity where the second terminal device can request or provide an application or traffic, or mobility information of the second terminal device.

[0233] In an embodiment, the mobility information of the second terminal device may indicate whether the second terminal device is in a stationary state or is moving.

[0234] In an embodiment, the second connectivity-related information may include a serving network node of the second terminal device, an indication of whether the second terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the second terminal device, the load or congestion status of the PC5 or Uu link, the radio access technology (RAT) of the PC5 or Uu link, an indication of the type of relay that the second terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the second terminal device can request or provide.

[0235] In an embodiment, the memory (730) may further include instructions executable by the processor (720), thereby the first terminal device (700) operates to: obtain a set of relay candidates including a second terminal device based on at least a second message; select the second terminal device as a relay between the first terminal device and a network node or a third terminal device based on second application or traffic-related information, second location or mobility-related information, and / or second connectivity-related information from the set of relay candidates; and establish a relay path from the first terminal device to the network node or a third terminal device via the second terminal device.

[0236] In an embodiment, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid, and the selecting operation may be based on the second validity timer.

[0237] In an embodiment, the memory (730) may further include instructions executable by the processor (720), thereby allowing the first terminal device (700) to: select, from a set of relay candidates, a fourth terminal device as a relay between the first terminal device and a network node or a third terminal device in response to a failure of the relay path, based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device; and operate to establish a relay path from the first terminal device to the network node or a third terminal device via the fourth terminal device.

[0238] In an embodiment, the operation of selecting a fourth terminal may be based on a validity timer that indicates the duration for which information associated with the fourth terminal device is valid.

[0239] In an embodiment, the method may further include the step of initiating another discovery procedure through a sidelink when all relay candidates in the set have their individual validity timers expired.

[0240] In an embodiment, the first message may further include a measurement configuration for the second terminal device to measure a PC5 link toward a third terminal device or a fifth terminal device, or a Uu link toward a network node, and the second message may further include a measurement report for the PC5 link or the Uu link.

[0241] In an embodiment, the memory (730) may further include instructions executable by the processor (720), thereby enabling the first terminal device (700) to operate to receive a measurement configuration from a network node.

[0242] In an embodiment, the memory (730) may further include instructions executable by the processor (720), thereby enabling the first terminal device (700) to operate to receive authorization from a network node to initiate a discovery procedure.

[0243] In an embodiment, first location or mobility-related information and / or first connectivity-related information may be explicitly transmitted in one or more fields of the first message or included in a container of the first message.

[0244] In an embodiment, second location or mobility-related information and / or second connectivity-related information may be explicitly received in one or more fields of the second message or included in a container of the second message.

[0245] Corresponding to the method (400) described above, a second terminal device is provided. FIG. 8 is a block diagram of a second terminal device (800) according to an embodiment of the present disclosure. The second terminal device (800) may be, for example, a monitoring UE of Model A or a discoverer UE of Model B. The second terminal device (800) may function as an RM UE or an RL UE.

[0246] The second terminal device (800) may be configured to perform the method (400) as described above in relation to FIG. 4. As illustrated in FIG. 8, the second terminal device (800) includes a receiving unit (810) configured to receive a first message from the first terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0247] In an embodiment, the first application or traffic-related information may include a QoS profile of an application or traffic that the first terminal device may request or provide.

[0248] In the embodiments, the QoS profile may include the type of application or traffic, priority, and / or QoS requirements.

[0249] In an embodiment, the first location or mobility-related information may include one or more of the location information of the first terminal device, information about an area or proximity where the first terminal device can request or provide an application or traffic, or mobility information of the first terminal device.

[0250] In an embodiment, the mobility information of the first terminal device may indicate whether the first terminal device is in a stationary state or is moving.

[0251] In an embodiment, the first connectivity-related information may include a serving network node of the first terminal device, an indication of whether the first terminal device can request or provide a relay path toward the network node or the terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the first terminal device, the load or congestion status of the PC5 or Uu link, the RAT of the PC5 or Uu link, an indication of the type of relay that the first terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the first terminal device can request or provide.

[0252] In an embodiment, the second terminal device (800) may further include: an acquisition unit configured to acquire a set of relay candidates including the first terminal device based on at least a first message; a selection unit configured to select the first terminal device as a relay between the second terminal device and a network node or a third terminal device based on first application or traffic-related information, first location or mobility-related information, and / or first connectivity-related information from the set of relay candidates; and an establishment unit configured to establish a relay path from the second terminal device to the network node or a third terminal device via the first terminal device.

[0253] In an embodiment, the first message may further include a first validity timer indicating a valid duration for information associated with the first terminal device, and the first terminal device may be selected based on the first validity timer.

[0254] In an embodiment, the selection unit may be further configured to select, in response to a failure of the relay path, from a set of relay candidates, the fourth terminal device as a relay between the second terminal device and the network node or the third terminal device based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device. The establishment unit may be further configured to establish a relay path from the second terminal device to the network node or the third terminal device via the fourth terminal device.

[0255] In an embodiment, the fourth terminal may be selected based on a validity timer that indicates the duration for which information associated with the fourth terminal device is valid.

[0256] In an embodiment, the second terminal device (800) may further include an initiation unit configured to initiate another discovery procedure via a sidelink when all relay candidates of the set have their individual validity timers expired.

[0257] In an embodiment, the second terminal device (800) may further include a transmitting unit configured to transmit a second message to the first terminal device in response to a first message. The second message may include one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information.

[0258] In an embodiment, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid.

[0259] In an embodiment, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device, and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0260] In an embodiment, the second application or traffic-related information may include a QoS profile of an application or traffic that the second terminal device may request or provide.

[0261] In an embodiment, the QoS profile may include the type of application or traffic that the second terminal device may request or provide, priority, and / or QoS requirements.

[0262] In an embodiment, the second location or mobility-related information may include one or more of the location information of the second terminal device, information about an area or proximity where the second terminal device can request or provide an application or traffic, or mobility information of the second terminal device.

[0263] In an embodiment, the mobility information of the second terminal device may indicate whether the second terminal device is in a stationary state or is moving.

[0264] In an embodiment, the second connectivity-related information may include a serving network node of the second terminal device, an indication of whether the second terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the second terminal device, the load or congestion status of the PC5 or Uu link, the RAT of the PC5 or Uu link, an indication of the type of relay that the second terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the second terminal device can request or provide.

[0265] In an embodiment, the first message may further include a measurement configuration for the second terminal device to measure a PC5 link toward a third terminal device or a fifth terminal device, or a Uu link toward a network node, and the second message may further include a measurement report for the PC5 link or the Uu link.

[0266] In an embodiment, the receiving unit (810) may be additionally configured to receive a measurement configuration from a network node.

[0267] In an embodiment, the receiving unit (810) may be further configured to receive authorization from a network node to participate in the discovery procedure.

[0268] In an embodiment, first location or mobility-related information and / or first connectivity-related information may be explicitly received in one or more fields of the first message or included in a container of the first message.

[0269] In an embodiment, second location or mobility-related information and / or second connectivity-related information may be explicitly transmitted in one or more fields of the second message or included in a container of the second message.

[0270] The above unit (810) may be implemented as a pure hardware solution or as a combination of software and hardware, for example, by a processor or microprocessor and suitable software and memory for storing software, a programmable logic device (PLD), or one or more of other electronic components or processing circuits configured to perform the actions described above, for example, illustrated in FIG. 4.

[0271] FIG. 9 is a block diagram of a second terminal device (900) according to another embodiment of the present disclosure. The second terminal device (900) may be, for example, a monitoring UE of Model A or a discoverer UE of Model B. The second terminal device (900) may function as an RM UE or an RL UE.

[0272] The second terminal device (900) includes a transceiver (910), a processor (920), and a memory (930). The memory (930) includes instructions executable by the processor (920), thereby enabling the second terminal device (900) to operate to perform actions of the procedure described above, for example, in relation to FIG. 4. In particular, the memory (930) may include instructions executable by the processor (920), thereby enabling the second terminal device (900) to operate to receive a first message from the first terminal device to initiate a discovery procedure via a sidelink. The first message includes one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information.

[0273] In an embodiment, the first application or traffic-related information may include a QoS profile of an application or traffic that the first terminal device may request or provide.

[0274] In the embodiments, the QoS profile may include the type of application or traffic, priority, and / or QoS requirements.

[0275] In an embodiment, the first location or mobility-related information may include one or more of the location information of the first terminal device, information about an area or proximity where the first terminal device can request or provide an application or traffic, or mobility information of the first terminal device.

[0276] In an embodiment, the mobility information of the first terminal device may indicate whether the first terminal device is in a stationary state or is moving.

[0277] In an embodiment, the first connectivity-related information may include a serving network node of the first terminal device, an indication of whether the first terminal device can request or provide a relay path toward the network node or the terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the first terminal device, the load or congestion status of the PC5 or Uu link, the RAT of the PC5 or Uu link, an indication of the type of relay that the first terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the first terminal device can request or provide.

[0278] In an embodiment, the memory (930) may further include instructions executable by the processor (920), thereby the second terminal device (900) operates to: obtain a set of relay candidates including the first terminal device based on at least a first message; select the first terminal device as a relay between the second terminal device and a network node or a third terminal device based on the set of relay candidates, first application or traffic-related information, first location or mobility-related information, and / or first connectivity-related information; and establish a relay path from the second terminal device to the network node or a third terminal device via the first terminal device.

[0279] In an embodiment, the first message may further include a first validity timer indicating the duration for which information associated with the first terminal device is valid, and the selecting operation may be based on the first validity timer.

[0280] In an embodiment, the memory (930) may further include instructions executable by the processor (920), thereby allowing the second terminal device (900) to: select, from a set of relay candidates, a fourth terminal device as a relay between the second terminal device and a network node or a third terminal device in response to a failure of a relay path, based on application or traffic-related information, location or mobility-related information, and / or connectivity-related information associated with the fourth terminal device; and operate to establish a relay path from the second terminal device to the network node or a third terminal device via the fourth terminal device.

[0281] In an embodiment, the operation of selecting a fourth terminal may be based on a validity timer that indicates the duration for which information associated with the fourth terminal device is valid.

[0282] In an embodiment, the memory (930) may further include instructions executable by the processor (920), thereby causing the second terminal device (900) to operate so that when all relay candidates in the set have their individual validity timers expire, another discovery procedure is initiated via a sidelink.

[0283] In an embodiment, the memory (930) may further include instructions executable by the processor (920), thereby enabling the second terminal device (900) to operate to transmit a second message to the first terminal device in response to a first message. The second message may include one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information.

[0284] In an embodiment, the second message may further include a second validity timer indicating the duration for which information associated with the second terminal device is valid.

[0285] In an embodiment, the identifier information may include one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device, and / or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device.

[0286] In an embodiment, the second application or traffic-related information may include a QoS profile of an application or traffic that the second terminal device may request or provide.

[0287] In an embodiment, the QoS profile may include the type of application or traffic that the second terminal device may request or provide, priority, and / or QoS requirements.

[0288] In an embodiment, the second location or mobility-related information may include one or more of the location information of the second terminal device, information about an area or proximity where the second terminal device can request or provide an application or traffic, or mobility information of the second terminal device.

[0289] In an embodiment, the mobility information of the second terminal device may indicate whether the second terminal device is in a stationary state or is moving.

[0290] In an embodiment, the second connectivity-related information may include a serving network node of the second terminal device, an indication of whether the second terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the second terminal device, the load or congestion status of the PC5 or Uu link, the RAT of the PC5 or Uu link, an indication of the type of relay that the second terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the second terminal device can request or provide.

[0291] In an embodiment, the first message may further include a measurement configuration for the second terminal device to measure a PC5 link toward a third terminal device or a fifth terminal device, or a Uu link toward a network node, and the second message may further include a measurement report for the PC5 link or the Uu link.

[0292] In an embodiment, the memory (930) may further include instructions executable by the processor (920), thereby enabling the second terminal device (900) to operate to receive a measurement configuration from a network node.

[0293] In an embodiment, the memory (930) may further include instructions executable by the processor (920), thereby enabling the second terminal device (900) to operate to receive authorization from a network node to participate in a discovery procedure.

[0294] In an embodiment, first location or mobility-related information and / or first connectivity-related information may be explicitly received in one or more fields of the first message or included in a container of the first message.

[0295] In an embodiment, second location or mobility-related information and / or second connectivity-related information may be explicitly transmitted in one or more fields of the second message or included in a container of the second message.

[0296] Corresponding to the method (500) described above, a network node is provided. FIG. 10 is a block diagram of a network node (1000) according to an embodiment of the present disclosure. The network node (1000) may be, for example, a serving network node of the first or second terminal device.

[0297] A network node (1000) may be configured to perform the method (500) described above in relation to FIG. 5. As illustrated in FIG. 10, the network node (1000) includes a transmission unit (1010) configured to transmit to a terminal device an authorization to initiate a discovery procedure or to participate in a discovery procedure; and to transmit to the terminal device a measurement configuration for the terminal device to measure a PC5 link or a Uu link toward the network node or another terminal device.

[0298] In the embodiments, authorization and / or measurement configurations may be transmitted via SIB or RRC signaling.

[0299] The above unit (1010) may be implemented as a pure hardware solution or as a combination of software and hardware, for example, by a processor or microprocessor and suitable software and memory for storing software, a programmable logic device (PLD), or one or more of other electronic components or processing circuits configured to perform the actions described above, for example, illustrated in FIG. 5.

[0300] FIG. 11 is a block diagram of a network node (1100) according to another embodiment of the present disclosure. The network node (1100) may be, for example, a serving network node of the first or second terminal device.

[0301] A network node (1100) includes a transceiver (1110), a processor (1120), and a memory (1130). The memory (1130) includes instructions executable by the processor (1120), thereby enabling the network node (1100) to operate to perform actions of the procedure described above, for example, in relation to FIG. 5. In particular, the memory (1130) may include instructions executable by the processor (1120), thereby enabling the network node (1100) to: transmit to a terminal device an authorization to initiate a discovery procedure or to participate in a discovery procedure; and transmit to a terminal device a measurement configuration for the terminal device to measure a PC5 link or a Uu link toward the network node or another terminal device.

[0302] In the embodiments, authorization and / or measurement configurations may be transmitted via SIB or RRC signaling.

[0303] The present disclosure also provides at least one computer program product in the form of a non-volatile or volatile memory, e.g., a non-transient computer-readable storage medium, an electrically eraseable programmable read-only memory (EEPROM), a flash memory, and a hard drive. The computer program product includes a computer program. The computer program includes code / computer-readable instructions that, when executed by a processor (720), cause a first terminal device (700) to perform actions of a procedure previously described, e.g., in relation to FIG. 3, or code / computer-readable instructions that, when executed by a processor (920), cause a second terminal device (900) to perform actions of a procedure previously described, e.g., in relation to FIG. 4, or code / computer-readable instructions that, when executed by a processor (1120), cause a network node (1100) to perform actions of a procedure previously described, e.g., in relation to FIG. 5.

[0304] A computer program product may be composed of computer program code structured into computer program modules. The computer program modules may essentially perform the actions of the flow exemplified in FIG. 3, FIG. 4, or FIG. 5.

[0305] The processor may be a single CPU (Central Processing Unit), but may include two or more processing units. For example, the processor may include general-purpose microprocessors; instruction set processors and / or related sets of chips and / or special-purpose microprocessors, such as Application Specific Integrated Circuits (ASICs). The processor may include board memory for caching purposes. A computer program may be carried by a computer program product connected to the processor. The computer program product may include a non-transient computer-readable storage medium in which the computer program is stored. For example, the computer program product may be flash memory, Random-Access Memory (RAM), Read-Only Memory (ROM), or EEPROM, and the computer program modules described above may be distributed among different computer program products in the form of memories in alternative embodiments.

[0306] Referring to FIG. 12, according to an embodiment, the communication system includes a telecommunication network (1210), such as a 3GPP-type cellular network, comprising an access network (1211), such as a radio access network, and a core network (1214). The access network (1211) includes a plurality of base stations (1212a, 1212b, 1212c), such as NBs, eNBs, gNBs, or other types of wireless access points, each of which defines a corresponding coverage area (1213a, 1213b, 1213c). Each base station (1212a, 1212b, 1212c) can be connected to the core network (1214) via a wired or wireless connection (1215). A first UE (1291) located in a coverage area (1213c) is configured to be wirelessly connected to or paginated by a corresponding base station (1212c). A second UE (1292) located in a coverage area (1213a) can be wirelessly connected to a corresponding base station (1212a). Although multiple UEs (1291, 1292) are illustrated in this example, the disclosed embodiments are equally applicable to situations where a single UE is in a coverage area or a single UE is connected to a corresponding base station (1212).

[0307] The telecommunication network (1210) itself is connected to a host computer (1230) which may be implemented as hardware and / or software of a standalone server, a cloud-implemented server, or a distributed server, or as processing resources of a server farm. The host computer (1230) may be owned or controlled by a service provider, or may be operated by or on behalf of a service provider. Connections (1221 and 1222) between the telecommunication network (1210) and the host computer (1230) may extend directly from the core network (1214) to the host computer (1230), or may pass through an optional intermediate network (1220). The intermediate network (1220) may be one of a public, private, or host network, or a combination of more than one of these; the intermediate network (1220) (if any) may be a backbone network or the Internet; In particular, the intermediate network (1220) may include two or more sub-networks (not shown).

[0308] The communication system of FIG. 12 enables connectivity between connected UEs (1291, 1292) and a host computer (1230) in its entirety. Connectivity can be described as an over-the-top (OTT) connection (1250). The host computer (1230) and the connected UEs (1291, 1292) are configured to communicate data and / or signaling via the OTT connection (1250), using an access network (1211), a core network (1214), any intermediate network (1220), and possible additional infrastructure (not shown) as intermediaries. The OTT connection (1250) may be transparent in that the participating communication devices through which the OTT connection (1250) passes do not know the routing of the uplink and downlink communications. For example, the base station (1212) may not be notified, or does not need to be notified, of past routing of incoming downlink communication having data originating from the host computer (1230) to be forwarded (e.g., handover) to the connected UE (1291). Similarly, the base station (1212) does not need to know of future routing of outgoing uplink communication originating from the UE (1291) toward the host computer (1230).

[0309] Exemplary implementations according to embodiments of the UE, base station, and host computer discussed in previous paragraphs will now be described with reference to FIG. 13. In a communication system (1300), a host computer (1310) includes hardware (1315) comprising a communication interface (1316) configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system (1300). The host computer (1310) further includes a processing circuit (1318) capable of having storage and / or processing capabilities. In particular, the processing circuit (1318) may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) adapted to execute instructions. The host computer (1310) further includes software (1311) stored in the host computer (1310), accessible by the host computer (1310), and executable by the processing circuit (1318). The software (1311) includes a host application (1312). The host application (1312) may be operable to provide services to a remote user, such as a UE (1330), connected via an OTT connection (1350) that terminates at the UE (1330) and the host computer (1310). In providing services to the remote user, the host application (1312) may provide user data transmitted using the OTT connection (1350).

[0310] The communication system (1300) further includes a base station (1320) which is provided to the telecommunication system and includes hardware (1325) that enables communication with a host computer (1310) and a UE (1330). The hardware (1325) may include a communication interface (1326) for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system (1300), as well as a radio interface (1327) for setting up and maintaining a wireless connection (1370) with a UE (1330) located in a coverage area (not shown in FIG. 13) served by at least the base station (1320). The communication interface (1326) may be configured to facilitate a connection (1360) to the host computer (1310). The connection (1360) may be direct or pass through a core network of the telecommunication system (not shown in FIG. 13) and / or pass through one or more intermediate networks outside the telecommunication system. In the illustrated embodiment, the hardware (1325) of the base station (1320) further includes a processing circuit section (1328) which may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) adapted to execute instructions. The base station (1320) further has software (1321) stored internally or accessible via an external connection.

[0311] The communication system (1300) further includes the previously mentioned UE (1330). Its hardware (1335) may include a radio interface (1337) configured to set up and maintain a radio connection (1370) with a base station serving the coverage area where the UE (1330) is currently located. The hardware (1335) of the UE (1330) further includes a processing circuit (1338) which may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) adapted to execute instructions. The UE (1330) further includes software (1331) stored in the UE (1330) or accessible by the UE (1330) and executable by the processing circuit (1338). The software (1331) includes a client application (1332). A client application (1332) may be able to operate to provide services to a human or non-human user via a UE (1330) with the support of a host computer (1310). On the host computer (1310), a host application (1312) running may communicate with a client application (1332) running via an OTT connection (1350) that terminates on the UE (1330) and the host computer (1310). In providing services to a user, the client application (1332) may receive request data from the host application (1312) and provide user data in response to the request data. The OTT connection (1350) may transmit both the request data and the user data. The client application (1332) may interact with the user to generate the user data it provides.

[0312] Note that the host computer (1310), base station (1320), and UE (1330) exemplified in FIG. 13 may be similar or identical to the host computer (1930), one of the base stations (1912a, 1912b, 1912c), and one of the UEs (1991, 1992) of FIG. 12, respectively. That is, the internal operations of these entities may be the same as those shown in FIG. 13, and independently thereof, the peripheral network topology may be that of FIG. 12.

[0313] In FIG. 13, the OTT connection (1350) is illustrated abstractly to exemplify communication between a host computer (1310) and a UE (1330) via a base station (1320) without explicit mention of any intermediary devices and the exact routing of messages passing through these devices. The network infrastructure may determine routing, which may be configured to be hidden from the UE (1330), from the service provider operating the host computer (1310), or from both. While the OTT connection (1350) is active, the network infrastructure may make further decisions to dynamically change routing (e.g., based on network load balancing considerations or reconfiguration).

[0314] The wireless connection (1370) between the UE (1330) and the base station (1320) follows the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE (1330) by using an OTT connection (1350) in which the wireless connection (1370) forms the final segment. More precisely, the teachings of these embodiments can improve communication quality and efficiency, thereby providing benefits such as reduced user waiting time.

[0315] A measurement procedure may be provided for the purpose of monitoring data rates, latency, and other factors improved by one or more embodiments. In response to changes in the measurement results, there may be additional optional network functionality for reconfiguring the OTT connection (1350) between the host computer (1310) and the UE (1330). The measurement procedure and / or network functionality for reconfiguring the OTT connection (1350) may be implemented in the software (1311) and hardware (1315) of the host computer (1310) or in the software (1331) and hardware (1335) of the UE (1330), or in both. In embodiments, sensors (not shown) may be deployed to or associated with communication devices through which the OTT connection (1350) passes; Sensors may participate in the measurement procedure by supplying values ​​of the monitored quantities exemplified above, or by supplying values ​​of other physical quantities that allow the software (1311, 1331) to calculate or estimate the monitored quantities. Reconfiguration of the OTT connection (1350) may include message formats, retransmission settings, preferred routing, etc.; reconfiguration does not need to affect the base station (1320), which may not be known or perceptible to the base station (1320). Such procedures and functionalities are known in the art and may be implemented. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of the throughput, propagation times, latency, etc. of the host computer (1310). Measurements may be implemented in such a way that while monitoring propagation times, errors, etc., the software (1311 and 1331) uses the OTT connection (1350) to transmit messages, particularly empty or 'dummy' messages.

[0316] FIG. 14 is a flowchart illustrating a method implemented in a communication system according to an embodiment. The communication system includes a host computer, a base station, and a UE, which may be those described with reference to FIG. 12 and FIG. 13. For the sake of simplification of the disclosure, only references to FIG. 14 will be included in this section. In step (1410), the host computer provides user data. In a substep (1411) of step (1410) (which may be optional), the host computer provides user data by executing a host application. In step (1420), the host computer initiates a transmission carrying user data to the UE. In step (1430) (which may be optional), the base station transmits the user data carried in the transmission initiated by the host computer to the UE, in accordance with the teachings of the embodiments described throughout the disclosure. In step (1440) (which may also be optional), the UE executes a client application associated with the host application executed by the host computer.

[0317] FIG. 15 is a flowchart illustrating a method implemented in a communication system according to an embodiment. The communication system includes a host computer, a base station, and a UE, which may be those described with reference to FIG. 12 and FIG. 13. For the sake of simplification of the disclosure, only references to FIG. 15 will be included in this section. In step (1510) of the method, the host computer provides user data. In an optional sub-step (not shown), the host computer provides user data by running a host application. In step (1520), the host computer initiates a transmission carrying user data to the UE. The transmission may pass through a base station, in accordance with the teachings of the embodiments described throughout the disclosure. In step (1530) (which may be optional), the UE receives the user data carried in the transmission.

[0318] FIG. 16 is a flowchart illustrating a method implemented in a communication system according to an embodiment. The communication system includes a host computer, a base station, and a UE, which may be those described with reference to FIG. 12 and FIG. 13. For the sake of simplification of the disclosure, only references to FIG. 16 will be included in this section. In step (1610) (which may be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step (1620), the UE provides user data. In a substep (which may be optional) of step (1620) (1621), the UE provides user data by executing a client application. In a substep (1611) of step (1610) (which may be optional), the UE executes a client application that provides user data in response to the received input data provided by the host computer. In providing user data, the executed client application may further consider user input received from the user. Regardless of the specific method in which user data is provided, the UE initiates the transmission of user data to a host computer in a sub-step (1630) (which may be optional). In step (1640) of the method, the host computer receives user data transmitted from the UE in accordance with the teachings of the embodiments described throughout this disclosure.

[0319] FIG. 17 is a flowchart illustrating a method implemented in a communication system according to an embodiment. The communication system includes a host computer, a base station, and a UE, which may be those described with reference to FIG. 12 and FIG. 13. For the sake of simplification of the disclosure, only references to FIG. 17 will be included in this section. In step (1710) (which may be optional), according to the teachings of the embodiments described throughout the disclosure, the base station receives user data from the UE. In step (1720) (which may be optional), the base station initiates the transmission of the received user data to the host computer. In step (1730) (which may be optional), the host computer receives the user data carried in the transmission initiated by the base station.

[0320] The present disclosure has been described above with reference to the embodiments. It should be understood that various modifications, changes, and additions may be made by those skilled in the art without departing from the spirit and scope of the present disclosure. Accordingly, the scope of the present disclosure is not limited to the specific embodiments described above but is defined only by the appended claims.

[0321] Below, the solutions will be further explained as follows.

[0322] The methods and solutions disclosed in this disclosure are based on the following novel aspects:

[0323] · Sidelink discovery announcements and response messages are enhanced with additional information regarding, for example, the following (but not limited to).

[0324] o Types of traffic that a remote UE needs to transmit toward a network or another remote UE,

[0325] o Requirements are expected to be met

[0326] o Channel quality of the relay UE toward the NW or other remote UE

[0327] o The number of remote UEs for which the relay UE currently has an established relay path.

[0328] · When a relay UE transmits a discovery announcement or response message, it includes a timer to inform the remote UE of how long the received information is valid. Alternatively, this validity timer may be configured by the network or fixed in the specification (e.g., a validity timer unique to all relay UEs).

[0329] When the remote UE receives all discovery announcements or responses from nearby relay UEs, it creates a list by sorting the relay UEs according to specific criteria (e.g., the type of traffic the relay UE can provide, the current channel states of the relay UE toward the NW or other remote UEs, the number of remote UEs that the relay UE has a relay path to).

[0330] o When the list is constructed, the remote UE attempts to establish a relay path with the first relay UE in the list. However, if the relay path establishment fails, the remote UE may avoid performing the discovery procedure again by selecting the second relay UE in the list (unless the discovery validity timer for the given remote UE has expired). The procedure will continue until a suitable relay UE is found or a new discovery procedure needs to be triggered (i.e., this means that the discovery validity timers for all relay UEs in the list have expired).

[0331] According to the methods and solutions disclosed in this disclosure, latency, power consumption, and signaling overhead are improved when performing discovery procedures in UE-to-NW and UE-to-UE relay scenarios.

[0332] This will be particularly important when requirements for public safety and V2X use cases need to be met.

[0333] The methods and solutions disclosed below refer to NR RATs but are applicable to LTE RATs and any other RATs, enabling transmission from two peripheral devices without any loss of semantics.

[0334] In addition, the RM UE is referred to as a remote UE that needs to send / receive packets from / to a gNB or another UE (referred to as the receiver remote UE) via an intermediate network node / mobile terminal (relay) referred to as the RL UE.

[0335] The proposed methods and solutions can be applied to UE-to-NW and UE-to-UE scenarios and L2 and L3 architectures (and any combination thereof) without any loss of semantics.

[0336] The embodiments use the terms "announcement message" or "solicitation message" to denote a first message regarding the discovery procedure. The embodiments use the terms "response" or "report" to denote a second message regarding the discovery procedure. The embodiments are not limited by any of the terms. Any similar terms are interchangeably applicable.

[0337] The embodiments are applicable to both Discovery Model A and Discovery Model B.

[0338] initiation UE Examples (Initiating the discovery procedure UE )

[0339] In the first embodiment, before establishing a relay path connection between the remote UE and the relay UE, the initiating UE (the remote UE or the relay UE) initiates a discovery procedure. The content of the information captured in Section 6.1.2.2 of TR 23.752, namely,

[0340] 1) ProSe UE ID, e.g., ProSe Application User ID, Layer 2 ID.

[0341] 2) Group ID(s) provided by the application layer.

[0342] 3) Application ID(s) or ProSe application code(s) that provided the application layer

[0343] In addition, the first message of PC5 may also include at least one of the following information (but not limited thereto):

[0344] · QoS profile of traffic or application of interest

[0345] o For example, the type of traffic or application of interest, priority index, QoS requirements

[0346] · Location information or proximity or area of ​​interest where traffic or applications of the initiating UE or UEs of interest will occur

[0347] · Mobility information of the initiating UE or UEs of interest

[0348] o (whether the UE is stationary or moving, and the type of mobility, e.g., pedestrian, vehicle)

[0349] · Validity timer for how long the provided information is valid

[0350] · Serving gNB for initiating UEs or UEs of interest

[0351] · Destination ID (this may only indicate whether the ID or the endpoint of the traffic is a cellular NW or another UE)

[0352] · IDs of adjacent UEs (if already found); this information may be used to assist the discovery process.

[0353] · Radio channel quality indicators of related PC5 links or Uu links, these links are connected directly or indirectly to a relay path

[0354] · Load measurement or congestion status of related PC5 links or Uu links, these links are connected directly or indirectly to the relay path

[0355] · RAT type of related PC5 links or Uu links, these links are connected directly or indirectly to a relay path

[0356] · Relay type (UE to network relay or UE to UE relay)

[0357] · Number of hops in the entire relay path or the maximum number of hops in the entire relay path

[0358] In addition, for any ID above, the ID may be a temporary ID, which means that the ID can be used only for the discovery procedure. After the discovery procedure, the ID becomes invalid.

[0359] In the second embodiment, upon receiving the first discovery message, the receiving UE (e.g., relay or remote UE) may build a list of UEs capable of selecting one or more UEs (i.e., initiating the discovery procedure) and begin establishing a relay path between the receiving UE and them. The method of selecting candidate UEs and sorting candidate UEs in the list may consider one or more of the information elements described in the first embodiment.

[0360] In the third embodiment, when the remote UE sorts candidate relay UEs in a list (according to a specific criterion), the remote UE triggers the establishment of a relay path toward the first relay UE in the list (i.e., in the first position).

[0361] · If the relay path establishment with the selected relay UE is successful, the discovery procedure is terminated, and the remote UE clears the list containing the discovered relay UEs from its memory. Alternatively, if the relay path establishment is successful, the remote UE maintains a list of candidate relay UEs in its memory and removes one (or more) relay UEs from this list only when the discovery validity timer for a given UE(s) expires. Also, in another alternative, if the relay path establishment is successful, the remote UE maintains a list of candidate relay UEs in its memory until a new discovery procedure is triggered.

[0362] · If relay path establishment with the selected relay UE fails, the remote UE triggers relay path establishment with the relay UE in the second position, provided that the discovery validity timer linked to this relay UE has not expired. The remote UE will continue scrolling through the list of relay UEs until the relay path establishment procedure succeeds or all relay UEs in the list have been tried.

[0363] In the fourth embodiment, for example, when the link quality between the remote UE and the relay UE deteriorates and the current relay path becomes unavailable, the remote UE may trigger path switching and path establishment with an available relay UE in a stored list of candidate relay UEs without first performing discovery, wherein an available relay UE means that the discovery validity timer linked to the relay UE has not expired. If relay path establishment fails for all available relay UEs in the list of candidate relay UEs, the discovery procedure may be initialized.

[0364] In the fifth embodiment, if the remote UE wants to know about the channel conditions that the relay UE has toward the destination of the relay path (e.g., a gNB or one or more destination UEs), the remote UE includes a measurement configuration within the discovery announcement message. The measurement configuration may also be provided by or pre-configured by the NW. Alternatively, the remote UE may include an interest in receiving measurements from the relay UE (which may be just a bit that the remote UE needs to tick).

[0365] response UE Examples (Responding to discovery requests UE - Discovery response).

[0366] In the sixth embodiment, at least one of the following information may be included in the second discovery message from the receiving UE (a relay or remote UE depending on whether Model A or Model B is applied) (but is not limited thereto):

[0367] ·UE Identity (Global)

[0368] · Relay UE ID (used only for relay communications)

[0369] · Temporary UE ID (can only be used for discovery procedures)

[0370] · Types of traffic that can be handled

[0371] · Channel measurements toward the destination of the relay path (e.g., gNB or other / multiple UEs)

[0372] · Location information.

[0373] · Traffic load from relay UEs via Uu and / or SL.

[0374] · Bearer / LCH that is allowed to be configured via supported QoS or Uu and / or SL.

[0375] · Mobility information (whether the relay UE is stationary or moving, and the type of mobility, e.g., pedestrian, vehicle)

[0376] · Serving gNB (if UE is in coverage)

[0377] · IDs of nearby UEs (if already found)

[0378] o This provides the IDs of the UEs connected / discovered by the relay UE in the case of a discovery announcement from the relay UE.

[0379] o This, in the case of a discovery response from a relay UE, indicates the destination UEs of the remote UE and the IDs of the UEs connected / discovered by the relay UE.

[0380] o Discovery announcements may include only the IDs of nearby UEs that have good channel quality for the relay UE. A threshold may be (pre)configured to determine whether the channel quality is sufficiently good.

[0381] · Validity timer advertising how long the provided information is valid

[0382] · Relay type (this indicates whether the endpoint of the possible relay path is a gNB (i.e., UE to NW relay) or another UE (UE to UE relay).

[0383] In the seventh embodiment, when measurements (toward, for, gNB or other / multiple UEs) are included in a discovery announcement / response message, the relay UE aligns these measurements based on the destination (e.g., gNB or one or multiple UEs) and based on RSRP, RSRQ, or SINR.

[0384] Additionally, if there are no available measurements at the time the relay UE transmits the discovery announcement / response, the relay UE first performs the measurements and then includes them in the discovery announcement / response message. When performing the measurements, the relay UE may use the configuration provided by the serving gNB (via the SIB or dedicated RRC signaling), or the configuration provided by the remote UE in the discovery request message, or a pre-configuration.

[0385] different Examples (NW Examples and implementation Examples )

[0386] In the eighth embodiment, the NW configures whether a UE is allowed to transmit discovery announcement / response messages within its coverage. The way the network configures its UEs can be through system information (SIB) or through dedicated RRC signaling. If the network allows one or more UEs to perform a discovery procedure, a measurement configuration to be used during the discovery procedure is also transmitted (the relay UE uses this measurement configuration when performing measurements before transmitting the discovery announcement / response).

[0387] In the ninth embodiment, if the remote / relay UE needs to include AS configuration / information within discovery messages, this is done explicitly within the discovery announcement or response message (meaning that AS-related fields are simply provided as "fields" within the discovery messages). Alternatively, instead of explicitly including this information as fields, AS-related configuration / parameters may be included in a container (OCTET STRING) within the discovery messages (meaning that the container will act as a pointer to part of the specification to which these AS-related configuration / parameters are standardized).

Claims

Claim 1 A method (300) at a first terminal device, comprising the step (310) of transmitting a first message to a second terminal device to initiate a discovery procedure via a side link, wherein the first message comprises one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information, and the first message further comprises a first validity timer indicating the duration for which the information associated with the first terminal device is valid. Claim 2 In claim 1, the method (300) comprises the first application or traffic-related information including a Quality of Service (QoS) profile of the application or traffic that the first terminal device may request or provide. Claim 3 Method (300), wherein, in claim 1 or 2, the first connectivity-related information comprises: a serving network node of the first terminal device; an indication of whether the first terminal device can request or provide a relay path toward the network node or terminal device; a list of identifiers of terminal devices obtained in a previous discovery procedure; an indication of the radio quality of the PC5 or Uu link currently possessed by the first terminal device; the load or congestion status of the PC5 or Uu link; the Radio Access Technology (RAT) of the PC5 or Uu link; an indication of the type of relay that the first terminal device can request or provide; or the number of hops or the maximum number of hops along the relay path that the first terminal device can request or provide. Claim 4 A method (300) according to claim 1 or 2, further comprising the step of receiving a second message from the second terminal device as a response to the first message, wherein the second message comprises one or more of the following information associated with the second terminal device: identifier information, second application or traffic-related information, second location or mobility-related information, or second connectivity-related information. Claim 5 In paragraph 4, the identifier information comprises one or more of the global identifier of the second terminal device, the temporary identifier of the second terminal device, or the identifier of the second terminal device used only when the second terminal device serves as a relay to the first terminal device, method (300). Claim 6 In paragraph 4, the second connectivity-related information comprises a serving network node of the second terminal device, an indication of whether the second terminal device can request or provide a relay path toward the network node or terminal device, a list of identifiers of terminal devices obtained in a previous discovery procedure, an indication of the radio quality of the PC5 or Uu link currently possessed by the second terminal device, the load or congestion status of the PC5 or Uu link, the radio access technology (RAT) of the PC5 or Uu link, an indication of the type of relay that the second terminal device can request or provide, or the number of hops or the maximum number of hops along the relay path that the second terminal device can request or provide. Method (300). Claim 7 A method (300) further comprising, in paragraph 4, the step of obtaining a set of relay candidates including the second terminal device based at least on the second message; the step of selecting the second terminal device as a relay between the first terminal device and the network node or the third terminal device based on the second application or traffic-related information, the second location or mobility-related information, or the second connectivity-related information from the set of relay candidates; and the step of establishing a relay path from the first terminal device to the network node or the third terminal device via the second terminal device. Claim 8 The method (300) of claim 7 further comprises: a step of, in response to a failure of the relay path, selecting from a set of relay candidates a fourth terminal device as a relay between the first terminal device and the network node or the third terminal device based on application or traffic-related information, location or mobility-related information, or connectivity-related information associated with the fourth terminal device; and a step of establishing a relay path from the first terminal device to the network node or the third terminal device via the fourth terminal device. Claim 9 A method (300) according to claim 7, further comprising the step of initiating another discovery procedure through the side link when all relay candidates of the set have their individual validity timers expired. Claim 10 In claim 7, the first message further includes a measurement configuration for the second terminal device to measure a PC5 link toward the third terminal device or the fifth terminal device, or a Uu link toward the network node, and the second message further includes a measurement report for the PC5 link or the Uu link, method (300). Claim 11 A method (300) in which, in claim 1 or 2, the first location or mobility-related information and / or the first connectivity-related information is explicitly transmitted in one or more fields of the first message or included in a container of the first message. Claim 12 A method (300) in which the second location or mobility-related information and / or the second connectivity-related information is explicitly received in one or more fields of the second message or included in a container of the second message. Claim 13 A method (400) at a second terminal device, comprising the step (410) of receiving a first message from a first terminal device to initiate a discovery procedure via a side link, wherein the first message comprises one or more of the following information associated with the first terminal device: first application or traffic-related information, first location or mobility-related information, or first connectivity-related information, and the first message further comprises a first validity timer indicating the duration for which the information associated with the first terminal device is valid. Claim 14 A first terminal device (700) comprising a transceiver (710), a processor (720), and a memory (730), wherein the memory (730) comprises instructions executable by the processor (720), and thereby the first terminal device (700) operates to perform the method of claim 1 or 2. Claim 15 A second terminal device (900) comprising a transceiver (910), a processor (920), and a memory (930), wherein the memory (930) comprises instructions executable by the processor (920), and thereby the second terminal device (900) operates to perform the method of claim 13. Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete Claim 21 delete Claim 22 delete Claim 23 delete Claim 24 delete Claim 25 delete Claim 26 delete Claim 27 delete Claim 28 delete Claim 29 delete Claim 30 delete Claim 31 delete Claim 32 delete Claim 33 delete Claim 34 delete Claim 35 delete Claim 36 delete Claim 37 delete Claim 38 delete Claim 39 delete Claim 40 delete Claim 41 delete Claim 42 delete Claim 43 delete Claim 44 delete Claim 45 delete Claim 46 delete Claim 47 delete Claim 48 delete Claim 49 delete Claim 50 delete Claim 51 delete Claim 52 delete Claim 53 delete Claim 54 delete Claim 55 delete Claim 56 delete

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