CN115707061A

CN115707061A - Relay selection method and device

Info

Publication number: CN115707061A
Application number: CN202110935416.2A
Authority: CN
Inventors: 邢玮俊; 李文正; 吴问付
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-08-16
Filing date: 2021-08-16
Publication date: 2023-02-17
Also published as: WO2023020297A1

Abstract

The application provides a relay selection method and a relay selection device, wherein the method comprises the following steps: the first terminal device determines a first relay selection policy applicable to the first relay device. And the first terminal equipment determines whether to establish side link connection with the first relay equipment according to the first relay selection strategy. According to the scheme of the application, before the terminal device judges whether the terminal device can access the network through a certain relay device, the relay selection strategy applicable to the relay device is firstly determined. In contrast, if the relay selection policy used by the terminal device is not applicable to the relay device, even if a sidelink connection is established between the terminal device and the relay device, the communication quality of the sidelink connection may not be as good as expected. Therefore, by adopting the scheme of the application, after the side link connection is established between the terminal equipment and the relay equipment, the communication quality between the terminal equipment and the relay equipment can achieve the expected effect, and a user can have better experience.

Description

Relay selection method and device

Technical Field

The present application relates to the field of communications technologies, and in particular, to a relay selection method and apparatus.

Background

To improve wireless spectrum utilization, cellular communication networks have introduced proximity-based services (ProSe) communications. When the terminal device is out of network coverage or the communication quality between the terminal device and the access network device is poor, the terminal device can perform auxiliary communication through the relay device. That is, the terminal device communicates with the relay device, and the relay device communicates with the access network device, so that the terminal device can access the network to obtain a corresponding service. However, when the terminal device selects the relay device, the selected relay device may not be suitable, so that the communication quality between the terminal device and the relay device may not achieve the expected effect, and the user experience may be affected. Therefore, how to select a suitable relay device by the terminal device when performing ProSe communication is an urgent problem to be solved.

Disclosure of Invention

The application provides a relay selection method and a relay selection device.

In a first aspect, a relay selection method is provided, including:

the first terminal device determines a first relay selection policy applicable to the first relay device. And the first terminal equipment determines whether to establish side link connection with the first relay equipment according to the first relay selection strategy.

According to the scheme of the application, before the terminal device judges whether the terminal device can access the network through a certain relay device, the relay selection strategy applicable to the relay device is firstly determined. In contrast, if the relay selection policy used by the terminal device is not applicable to the relay device, even if a sidelink connection is established between the terminal device and the relay device, the communication quality of the sidelink connection may not achieve the expected effect, which may affect the user experience on the one hand, and also cause a certain signaling waste (the sidelink connection may need to be reestablished) on the other hand. Therefore, by adopting the scheme of the application, after the side link connection is established between the terminal equipment and the relay equipment, the communication quality between the terminal equipment and the relay equipment can achieve the expected effect, so that a user can have better experience, and the signaling overhead can be saved to a certain extent.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes:

the first terminal equipment acquires first information, the first information indicates N relay selection strategies and N application ranges, the N application ranges correspond to the N relay selection strategies one to one, and N is a positive integer. The first terminal device acquires second information from the first relay device, the second information including position information of the first relay device.

The first terminal device determines a first relay selection strategy applicable to the first relay device, and the method comprises the following steps:

and the first terminal equipment determines a first relay selection strategy in the N relay selection strategies according to the second information, wherein the position of the first relay equipment is in an application range corresponding to the first relay selection strategy.

According to the scheme of the application, the terminal equipment can obtain a plurality of relay selection strategies and the application range of each relay selection strategy. On this basis, when the terminal device receives a discovery message of a certain relay device, a relay selection policy applicable to the relay device can be selected from a plurality of relay selection policies according to the location information of the relay device included in the discovery message.

the first terminal equipment acquires first indication information from the first relay equipment, wherein the first indication information comprises information of a first relay selection strategy.

and the first terminal equipment determines a first relay selection strategy according to the first indication information.

According to the scheme of the application, the discovery message sent by the relay device can carry the relay selection strategy applicable to the relay device. On this basis, when the terminal device receives the discovery message sent by the relay device, the relay selection strategy applicable to the relay device can be determined from the discovery message.

the first terminal device determines a second relay selection policy applicable to the second relay device. And the first terminal equipment determines whether to establish side link connection with the second relay equipment according to the second relay selection strategy.

With reference to the first aspect, in some implementations of the first aspect, the first relay selection policy includes a first threshold value, and the second relay selection policy includes a second threshold value. The method further comprises the following steps:

the first terminal device receives a first discovery message from the first relay device and a second discovery message from the second relay device.

The determining whether to establish a sidelink connection with the first relay device and the determining whether to establish a sidelink connection with the second relay device include:

and when the receiving power of the first discovery message is greater than a first threshold value and the receiving power of the second discovery message is less than or equal to a second threshold value, the first terminal equipment determines to establish a side link connection with the first relay equipment. And when the receiving power of the first discovery message is smaller than or equal to a first threshold value and the receiving power of the second discovery message is larger than a second threshold value, the first terminal equipment determines to establish a side link connection with the second relay equipment.

With reference to the first aspect, in some implementations of the first aspect, the first relay selection policy further includes a first priority, and the second relay selection policy further includes a second priority.

And under the condition that the receiving power of the first discovery message is greater than a first threshold value and the receiving power of the second discovery message is greater than a second threshold value, when the first priority is higher than the second priority, the first terminal equipment determines to establish a side link connection with the first relay equipment. When the first priority is lower than the second priority, the first terminal device determines to establish a sidelink connection with the second relay device.

According to the scheme of the application, when the appropriate relay equipment cannot be determined according to the first threshold value and the second threshold value, the appropriate relay equipment can be selected continuously according to the first priority and the second priority.

With reference to the first aspect, in certain implementations of the first aspect, the first priority is associated with a load of the first access network device and the second priority is associated with a load of the second access network device.

Wherein the first relay device is within the service range of the first access network device and the second relay device is within the service range of the second access network device.

It should be appreciated that the first priority is lower when the load of the first access network device is higher. The first priority is higher when the load of the first access network device is lower. Similarly, the second priority is lower when the load of the second access network device is higher. The second priority is higher when the load of the second access network device is lower.

In a second aspect, a relay selection method is provided, including:

the first terminal equipment acquires first information, the first information indicates N relay selection strategies and N application ranges, the N application ranges correspond to the N relay selection strategies one by one, and N is a positive integer. The first terminal device acquires second information from the first relay device, the second information including position information of the first relay device. And the first terminal equipment determines that the first relay equipment is applicable to a first relay selection strategy in the N relay selection strategies according to the second information, wherein the position of the first relay equipment is in an application range corresponding to the first relay selection strategy.

In a possible implementation manner, the N relay selection policies may be relay selection policies of a cell in which the first terminal device is located and of neighboring cells.

In another possible implementation manner, a cell in which the first terminal device is located may be further divided into N regions, and the N relay selection policies are in one-to-one correspondence with the N regions.

According to the scheme of the application, the terminal equipment can obtain a plurality of relay selection strategies and the application range of each relay selection strategy. On this basis, when the terminal device receives a discovery message of a certain relay device, a relay selection policy applicable to the relay device can be selected from a plurality of relay selection policies according to the location information of the relay device included in the discovery message. In contrast, if the relay selection policy used by the terminal device is not applicable to the relay device, even if a sidelink connection is established between the terminal device and the relay device, the communication quality of the sidelink connection may not achieve an expected effect, which may affect the user experience on the one hand and cause a certain signaling waste on the other hand (the sidelink connection may need to be reestablished). Therefore, by adopting the scheme of the application, after the side link connection is established between the terminal equipment and the relay equipment, the communication quality between the terminal equipment and the relay equipment can achieve the expected effect, so that a user can have better experience, and the signaling overhead can be saved to a certain extent.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes:

the first terminal device acquires third information from the second relay device, the third information including position information of the second relay device. And the first terminal equipment determines that the second relay equipment is suitable for a second relay selection strategy in the N relay selection strategies according to the third information, wherein the position of the second relay equipment is in an application range corresponding to the second relay selection strategy.

With reference to the second aspect, in some implementation manners of the second aspect, the first relay selection policy includes a first threshold, the second information is carried in the first discovery message, the second relay selection policy includes a second threshold, and the third information is carried in the second discovery message. The method further comprises the following steps:

With reference to the second aspect, in some implementations of the second aspect, the first relay selection policy further includes a first priority, and the second relay selection policy further includes a second priority. And under the condition that the receiving power of the first discovery message is greater than a first threshold value and the receiving power of the second discovery message is greater than a second threshold value, when the first priority is higher than the second priority, the first terminal equipment determines to establish a side link connection with the first relay equipment. When the first priority is lower than the second priority, the first terminal device determines to establish a sidelink connection with the second relay device.

In some implementations of the second facet in combination with the second aspect, the first priority is associated with a load of the first access network device and the second priority is associated with a load of the second access network device. Wherein the first relay device is within the service range of the first access network device and the second relay device is within the service range of the second access network device.

With reference to the second aspect, in some implementation manners of the second aspect, the first discovery message further includes third priority information, the second discovery message further includes fourth priority information, and when the third priority is higher than the fourth priority, the first terminal device determines to establish a sidelink connection with the first relay device, where the received power of the first discovery message is greater than a first threshold and the received power of the second discovery message is greater than a second threshold. And when the third priority is lower than the fourth priority, the first terminal equipment determines to establish the side link connection with the second relay equipment.

Wherein the third priority is associated with a load of the first relay device and the fourth priority is associated with a load of the second relay device.

In a third aspect, a relay selection method is provided, including:

the first terminal device obtains first indication information from the first relay device, wherein the first indication information comprises information of a first relay selection strategy, and the first relay selection strategy is a relay selection strategy applicable to the first relay device. And the first terminal equipment determines whether to establish side link connection with the first relay equipment according to the first relay selection strategy.

According to the scheme of the application, the discovery message sent by the relay device can carry the relay selection strategy applicable to the relay device. On this basis, when the terminal device receives the discovery message sent by the relay device, the relay selection strategy applicable to the relay device can be determined from the discovery message. In contrast, if the relay selection policy used by the terminal device is not applicable to the relay device, even if a sidelink connection is established between the terminal device and the relay device, the communication quality of the sidelink connection may not achieve an expected effect, which may affect the user experience on the one hand and cause a certain signaling waste on the other hand (the sidelink connection may need to be reestablished). Therefore, by adopting the scheme of the application, after the side link connection is established between the terminal equipment and the relay equipment, the communication quality between the terminal equipment and the relay equipment can achieve the expected effect, so that a user can have better experience, and the signaling overhead can be saved to a certain extent.

With reference to the third aspect, in certain implementations of the third aspect, the method further includes:

the first terminal device obtains second indication information from the second relay device, wherein the second indication information includes information of a second relay selection policy, and the second relay selection policy is a relay selection policy applicable to the second relay device. And the first terminal equipment determines whether to establish side link connection with the second relay equipment according to the second relay selection strategy.

With reference to the third aspect, in some implementation manners of the third aspect, the first relay selection policy includes a first threshold, the first indication information is carried in the first discovery message, the second relay selection policy includes a second threshold, and the second indication information is carried in the second discovery message.

and when the receiving power of the first discovery message is greater than a first threshold value and the receiving power of the second discovery message is less than or equal to a second threshold value, the first terminal equipment determines to establish a side link connection with the first relay equipment. And when the receiving power of the first discovery message is smaller than or equal to a first threshold value and the receiving power of the second discovery message is larger than a second threshold value, the first terminal equipment determines to establish side link connection with the second relay equipment.

With reference to the third aspect, in some implementations of the third aspect, the first relay selection policy further includes a first priority, and the second relay selection policy further includes a second priority. And under the condition that the receiving power of the first discovery message is greater than a first threshold value and the receiving power of the second discovery message is greater than a second threshold value, when the first priority is higher than the second priority, the first terminal equipment determines to establish a side link connection with the first relay equipment. When the first priority is lower than the second priority, the first terminal device determines to establish a sidelink connection with the second relay device.

With reference to the third aspect, in certain implementations of the third aspect, the first priority is associated with a load of the first access network device and the second priority is associated with a load of the second access network device. Wherein the first relay device is within service range of the first access network device and the second relay device is within service range of the second access network device.

With reference to the third aspect, in some implementation manners of the third aspect, the first relay selection policy further includes third priority information, the second relay selection policy further includes fourth priority information, and when the third priority is higher than the fourth priority, the first terminal device determines to establish a sidelink connection with the first relay device, where the received power of the first discovery message is greater than a first threshold and the received power of the second discovery message is greater than a second threshold. And when the third priority is lower than the fourth priority, the first terminal equipment determines to establish the side link connection with the second relay equipment. Wherein the third priority is associated with a load of the first relay device and the fourth priority is associated with a load of the second relay device.

In a fourth aspect, a relay selection method is provided, including:

the first access network equipment acquires a relay selection strategy of the adjacent cell access network equipment and an application range corresponding to the relay selection strategy of the adjacent cell access network equipment.

The first access network equipment sends first information, the first information indicates N relay selection strategies and N application ranges, the N application ranges are in one-to-one correspondence with the N relay selection strategies, and N is a positive integer.

The N relay selection strategies comprise a relay selection strategy of the first access network equipment and a relay selection strategy of the adjacent cell access network equipment.

In a fifth aspect, a relay selection method is provided, including:

the first relay device determines a first relay selection policy, the first relay selection policy being applicable to the first relay device.

The first relay equipment sends first indication information, and the first indication information comprises information of a first relay selection strategy.

In a sixth aspect, a communication device is provided, which includes means or units for performing the method of any one of the possible implementations of the first to fifth aspects.

In a seventh aspect, a communications apparatus is provided that includes at least one processor. The memory is used for storing a computer program, and when the communication device is running, the processor executes the computer program or instructions stored by the memory, so that the communication device executes the method in any one of the possible implementation manners of the first aspect to the fifth aspect.

In an eighth aspect, a computer-readable storage medium is provided, which comprises a computer program, which, when run on a computer, causes the computer to perform the method of any one of the possible implementations of the first aspect to the fifth aspect.

In a ninth aspect, a chip is provided, on which processing circuitry is arranged, the processing circuitry being configured to perform the method of any one of the possible implementations of the first aspect to the fifth aspect.

In a tenth aspect, there is provided a computer program product comprising: computer program (also called code, or instructions), which when executed, causes a computer to perform the method of any of the possible implementations of the first to fifth aspects

Drawings

Fig. 1 shows an architecture of a system to which an embodiment of the present application is applicable.

Fig. 2 shows an example of a schematic interaction diagram of the method proposed in the present application.

Fig. 3 shows an exemplary schematic interaction diagram of the method proposed by the present application.

Fig. 4 shows a schematic block diagram of a communication device as provided herein.

Fig. 5 shows another schematic block diagram of a communication device as provided herein.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

Fig. 1 shows an architecture of a communication system to which an embodiment of the present application is applicable.

Some terms referred to in this application are described below in conjunction with fig. 1.

1. Core network

The core network includes, but is not limited to, a data storage management network element, a mobility management network element, a network open network element, a user plane function network element, a session management network element, and the like.

The data storage management network element is a network element for storing and managing data of the terminal device, for example, in a 5G network, the network element may be a Unified Data Management (UDM) network element. In a future communication system, the network element with the unified data management function may still be a UDM network element, or may also have another name, which is not limited in this application.

A mobility management network element is a network element for managing mobility of a terminal device, for example, in a 4G network, a Mobility Management Entity (MME) may be used, and in a 5G network, an access and mobility management function (AMF) network element may be used. In a future communication system, the access and mobility management function network element may still be an AMF network element, or may also have another name, which is not limited in this application.

The network open network element is responsible for providing a function of a network to a third party application, for example, in a 5G network, the network open network element may be a network open function (NEF) network element. In future communication systems, the network element with the network open function may still be an NEF network element, or may also have another name, which is not limited in this application.

The user plane function network element is responsible for forwarding and receiving user data, and for example, in a 5G network, the user plane function network element may be a User Plane Function (UPF) network element. In a future communication system, the user plane function network element may still be a UPF network element, or may also have another name, which is not limited in this application.

The session management network element is responsible for selection of a user plane network element, internet Protocol (IP) address allocation, establishment, modification, release and the like of a session. For example, in a 5G network, it may be a Session Management Function (SMF) network element. In a future communication system, the session management function network element may still be an SMF network element, or may also have another name, which is not limited in this application.

2. Access network device

The access network device is a device providing a wireless communication function for a terminal device, and may be, for example, an Access Point (AP) in a WLAN, a base station (BTS) in GSM or CDMA, a base station (nodeB, NB) in WCDMA, or a gNB in a new radio system (NR) system, an evolved node B (eNB, or eNodeB) in LTE, or a radio access network device (RAN) in a 5G network.

3. Terminal device

A terminal device may refer to a User Equipment (UE), an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote terminal, a mobile device, a user terminal, a wireless communication device, a user agent, or a user equipment. The terminal device may also be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with wireless communication function, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a future 5G network or a terminal device in a future evolved Public Land Mobile Network (PLMN), and the like, which are not limited in this embodiment.

It should be understood that the terminal device in the present application supports proximity-based services (ProSe) communication. That is, the terminal device may establish a side link (side link) connection with the relay device, and access the network through the relay device. The terminal device and the relay device communicate with each other through a PC5 interface. When a terminal device accesses a network through a relay device, the terminal device may also be referred to as a remote UE (remote UE).

4. Relay device

The relay equipment also supports ProSe communication, the relay equipment communicates with the remote UE through a PC5 interface, and the relay equipment communicates with the access network equipment through a Uu interface. The relay device may be a terminal device or a wireless access device (e.g., an operator-deployed access device).

The scheme proposed in the present application is described in detail below with reference to fig. 2, and the scheme shown in fig. 2 can be applied to the communication system shown in fig. 1.

S201, an access network device #1 (an example of a first access network device) obtains a relay selection policy of an access network device in a neighboring cell and application range information corresponding to the relay selection policy.

Next, the application range information corresponding to the relay selection policy will be described in each case.

Case 1:

the applicable scope includes the scope of the access network equipment to which the relay selection policy is applicable.

For example, the applicable range includes identification information of the access network device to which the relay selection policy is applicable.

Case 2:

the applicable range includes a cell range to which the relay selection strategy is applicable.

For example, the applicable range includes identification (cell ID) information of a cell to which the relay selection policy is applicable.

Case 3:

the applicable scope includes a Public Land Mobile Network (PLMN) scope to which the relay selection policy is applicable.

For example, the applicable range includes identification (PLMN ID) information of a PLMN to which the relay selection policy is applicable.

Case 4:

the applicable range includes a geographical location range to which the relay selection policy is applicable.

For example, the applicable range includes an absolute position range determined by Global Positioning System (GPS) coordinates to which the relay selection policy is applicable. In one possible implementation, the applicable range may be a GPS coordinate range composed of a plurality of GPS coordinates.

For another example, the applicable range includes Tracking Area Identity (TAI) information of a Tracking Area (TA) to which the relay selection policy is applicable.

For another example, the applicable range includes identification (zone ID) information of an area to which the relay selection policy is applicable.

It should be understood that the applicability information may be any one of the above cases 1 to 4, or may be different combinations of the above cases 1 to 4, for example, a combination of the case 1 and the case 2, which is not limited in this application.

For the sake of convenience of description, the access network device #2 (an example of the second access network device) is an access network device adjacent to the access network device #1. Hereinafter, the relay selection policy corresponding to the access network device #1 is referred to as a relay selection policy #1, the application range information corresponding to the relay selection policy #1 is referred to as an application range #1, the relay selection policy corresponding to the access network device #2 is referred to as a relay selection policy #2, and the application range information corresponding to the relay selection policy #2 is referred to as an application range #2.

The following describes a manner in which the access network device #1 acquires the relay selection policy #2 and the applicable range #2.

Mode 1:

access network device #2 transmits relay selection policy #2 and application range #2 to access network device #1. Accordingly, the access network device #1 receives the relay selection policy #2 and the applicable range #2.

It should be understood that access network device #1 and access network device #2 may communicate directly, e.g., via wired or wireless means.

Mode 2:

the access network device #1 and the access network device #2 have a common management device.

The access network device #2 may transmit the relay selection policy #2 and the application range #2 to the management device, and the management device may transmit the relay selection policy #2 and the application range #2 to the access network device #1. Accordingly, the access network device #1 receives the relay selection policy #2 and the applicable range #2.

Mode 3:

the access network device #1 and the access network device #2 have a common management device. Relay selection policy #1 and application range #1 corresponding to access network device #1, and relay selection policy #2 and application range #2 corresponding to access network device #2 are preconfigured or generated in the management device.

In a possible implementation manner, the management device may generate a relay selection policy corresponding to each access network device according to information such as a location or a coverage of each access network device.

The management device transmits the relay selection policy #2 and the applicable range #2 to the access network device #1.

Mode 4:

a relay selection policy #2 and an applicable range #2 are preconfigured in the access network device #1.

In one possible implementation, the provisioning may be performed by an operator at the time of installation of the access network device #1 or at the time of factory configuration of the access network device #1.

It should be understood that, when the neighboring access network device of access network device #1 further includes other access network devices, the relay selection policy and the corresponding application range information of the other neighboring access network devices may be obtained in a manner similar to the manner 1-4 described above.

S202, the access network device #1 transmits first information including the relay selection policy #1 and the application range #1, the relay selection policy #2 and the application range #2, and first threshold information to the terminal device #1 (an example of a first terminal device) within its service range.

In one possible implementation, the access network device #1 may obtain the information of the relay selection policy #1, the applicable range #1, and the first threshold through the management device. Alternatively, the information of the relay selection policy #1, the application range #1, and the first threshold may be preconfigured in the access network device #1. This is not a limitation of the present application.

It will be appreciated that the first threshold acts as: when the power of the third reference signal sent by the access network device #1 received by a certain terminal device within the service range of the access network device #1 is smaller than the first threshold, the terminal device may initiate a process of selecting a relay device.

The following describes a manner of sending the first information by the access network device # 1:

mode 1:

the access network device #1 may transmit the first information to the terminal device #1 in a broadcast manner.

Mode 2:

when Radio Resource Control (RRC) connection is established between the terminal apparatus #1 and the access network apparatus #1, the access network apparatus #1 may transmit the first information to the terminal apparatus #1 through RRC signaling.

In one possible implementation, the method further includes: s203, the relay device #1 (an example of the first relay device) in the service range of the access network device #1 acquires the second information. The second information indicates the location of the relay apparatus #1. The relay device #2 (an example of the second relay device) within the service range of the access network device #2 acquires the third information. The third information indicates the location of the relay apparatus #2.

The second information and the third information can be classified into the following cases.

Case 1:

corresponding to case 1 in S201, the second information indicates the identity of access network device #1. The third information indicates the identity of access network device #2.

Case 2:

corresponding to case 2 in S201, the second information indicates the identity of the cell in which the relay apparatus #1 is located. The third information indicates the identity of the cell in which relay device #2 is located.

Case 3:

corresponding to case 3 in S201, the second information indicates the identity of the PLMN in which the relay apparatus #1 is located. The third information indicates the identity of the PLMN in which the relay device #2 is located.

Case 4:

corresponding to case 4 in S201, the second information indicates the geographical position where the relay apparatus #1 is located. The third information indicates the geographical location where the relay apparatus #2 is located.

For example, the second information indicates the GPS coordinates at which the relay apparatus #1 is located, or the second information indicates the identification of the tracking area at which the relay apparatus #1 is located, or the second information indicates the identification of the area at which the relay apparatus #1 is located. The third information indicates the GPS coordinates where the relay apparatus #2 is located, or the third information indicates the identification of the tracking area where the relay apparatus #2 is located, or the third information indicates the identification of the area where the relay apparatus #2 is located.

It should be understood that the location of the relay device #1 and the relay device #2 indicated by the identity of the access network device, the identity of the cell, the identity of the PLMN in case 1-case 3 above, and the identity of the tracking area, the identity of the area in case 4 may be inaccurate; the positions of the relay apparatus #1 and the relay apparatus #2 indicated by the GPS coordinates in case 4 may be accurate.

The manner in which the relay apparatus #1 acquires the second information and the relay apparatus #2 acquires the third information is described below:

mode 1:

the relay apparatus #1 acquires the second information from the access network apparatus #1, and the relay apparatus #2 acquires the third information from the access network apparatus #2. Specifically, the access network device #1 may transmit the second information to the relay device #1. The access network device #2 may transmit the third information to the relay device #2.

Mode 2:

the second information and the third information are preconfigured. That is, the second information is preconfigured in the relay apparatus #1, and the third information is preconfigured in the relay apparatus #2.

S204, the relay device #1 transmits a first discovery message including the second information. The relay device #2 transmits a second discovery message including the third information therein.

In a possible implementation manner, the first discovery message may include a first reference signal, and the second discovery message may include a second reference signal.

In a possible implementation manner, the first discovery message may further include third priority information, and the third priority information is associated with the load of the relay device #1. When the load of the relay apparatus #1 is high, the third priority is low; when the load of the relay apparatus #1 is low, the third priority is high.

Similarly, fourth priority information associated with the load of the relay apparatus #2 may be further included in the second discovery message. When the load of the relay apparatus #2 is high, the fourth priority is low; when the load of the relay apparatus #2 is low, the fourth priority is high.

In one possible implementation, the relay device may send the discovery message in a broadcast manner. That is, the relay apparatus #1 transmits the first discovery message by way of broadcasting. Relay device #2 transmits the second discovery message by way of broadcasting.

S205, when the power of the third reference signal transmitted by the access network device #1 received by the terminal device #1 is smaller than the first threshold, the terminal device #1 may initiate a process of selecting a relay device.

The following describes a procedure in which the terminal apparatus #1 selects a relay apparatus.

In S202, the terminal apparatus #1 has acquired first information including information of the relay selection policy #1 and the applicable range #1, the relay selection policy #2, and the applicable range #2.

The relay selection policy #1 includes a first threshold value. In one possible implementation, the relay selection policy #1 further includes first priority information, and the first priority information is associated with a load condition of the access network device #1. That is, when the load of the access network device #1 is relatively high, the first priority may be relatively low. When the load of the access network device #1 is relatively low, the first priority may be relatively high.

The relay selection policy #2 includes a second threshold value. In one possible implementation, the relay selection policy #2 further includes second priority information, and the second priority information is associated with a load condition of the access network device #2. That is, when the load of the access network device #2 is relatively high, the second priority may be relatively low. When the load of the access network device #2 is relatively low, the second priority may be relatively high.

Terminal apparatus #1 has received the first discovery message transmitted by relay apparatus #1 and the second discovery message transmitted by relay apparatus #2. Wherein, the first discovery message includes the second information, and the second discovery message includes the third information.

The terminal apparatus #1 determines, based on the second information, that the relay apparatus #1 is suitable for the relay selection policy #1. Wherein the second information indicates a location of relay apparatus #1, and the location of relay apparatus #1 is within application range #1 corresponding to relay selection policy #1.

Several cases in which the terminal apparatus #1 determines that the relay apparatus #1 is suitable for the relay selection policy #1 based on the second information are described below:

case 1:

corresponding to case 1 in S203, the second information indicates the identity of access network device #1. The application range #1 corresponding to the relay selection policy #1 includes the identifier of the access network device #1, and the application range #2 corresponding to the relay selection policy #2 does not include the identifier of the access network device #1. Terminal apparatus #1 determines that relay apparatus #1 is suitable for relay selection policy #1.

Case 2:

corresponding to case 2 in S203, the second information indicates the identity of cell #1 in which relay apparatus #1 is located. The application range #1 corresponding to the relay selection policy #1 includes the identifier of the cell #1, and the application range #2 corresponding to the relay selection policy #2 does not include the identifier of the cell #1. Terminal apparatus #1 determines that relay apparatus #1 is suitable for relay selection policy #1.

Case 3:

corresponding to case 3 in S203, the second information indicates the identity of PLMN #1 in which relay apparatus #1 is located. The application range #1 corresponding to the relay selection policy #1 includes the identifier of the PLMN #1, and the application range #2 corresponding to the relay selection policy #2 does not include the identifier of the PLMN #1. Terminal apparatus #1 determines that relay apparatus #1 is suitable for relay selection policy #1.

Case 4:

corresponding to case 4 in S203, the second information indicates the geographical location where the relay apparatus #1 is located.

For example, the second information indicates the first GPS coordinate at which relay device #1 is located, application range #1 corresponding to relay selection policy #1 is GPS coordinate range #1 composed of a plurality of GPS coordinates, and application range #2 corresponding to relay selection policy #2 is GPS coordinate range #2 composed of a plurality of GPS coordinates. The first GPS coordinate is located within the GPS coordinate range #1 and outside the GPS coordinate range #2, and the terminal apparatus #1 determines that the relay apparatus #1 is suitable for the relay selection policy #1.

For another example, the second information indicates an identifier of the tracking area #1 in which the relay device #1 is located, the identifier of the tracking area #1 is included in the application range #1 corresponding to the relay selection policy #1, and the identifier of the tracking area #1 is not included in the application range #2 corresponding to the relay selection policy #2. Terminal apparatus #1 determines that relay apparatus #1 is suitable for relay selection policy #1.

For another example, the second information indicates an identifier of area #1 in which relay device #1 is located, the identifier of area #1 is included in application range #1 corresponding to relay selection policy #1, and the identifier of area #1 is not included in application range #2 corresponding to relay selection policy #2. Terminal apparatus #1 determines that relay apparatus #1 is suitable for relay selection policy #1.

The terminal apparatus #1 determines that the relay apparatus #2 is suitable for the relay selection policy #2 based on the third information. This procedure is similar to the determination by the terminal apparatus #1 that the relay apparatus #1 is suitable for the relay selection policy #1 based on the second information, and a description thereof will not be provided.

Terminal apparatus #1 measures received power #1 of the first discovery message, and measures received power #2 of the second discovery message. It should be understood that, when the first reference signal is included in the first discovery message and the second reference signal is included in the second discovery message, the received power #1 may be the received power of the first reference signal and the received power #2 may be the received power of the second reference signal.

Terminal apparatus #1 determines whether received power #1 is greater than a first threshold value and received power #2 is greater than a second threshold value.

When the received power #1 is greater than the first threshold value and the received power #2 is less than or equal to the second threshold value, the terminal device may establish a sidelink connection with the relay device #1.

When the received power #1 is less than or equal to the first threshold value and the received power #2 is greater than the second threshold value, the terminal apparatus may establish a sidelink connection with the relay apparatus #2.

In the case where the received power #1 is greater than the first threshold and the received power #2 is greater than the second threshold, the terminal device may select an appropriate relay device to establish a sidelink connection according to the first priority to the fourth priority.

Specifically, when the first priority is higher than the second priority, the terminal apparatus may establish a sidelink connection with the relay apparatus #1. When the first priority is lower than the second priority, the terminal apparatus may establish a sidelink connection with the relay apparatus #2.

Alternatively, when the third priority is higher than the fourth priority, the terminal apparatus may establish a sidelink connection with the relay apparatus #1. When the third priority is lower than the fourth priority, the terminal apparatus may establish a sidelink connection with the relay apparatus #2.

Alternatively, when the first priority is equal to the second priority, the terminal device may continue to select an appropriate relay device according to the level of the third priority and the level of the fourth priority.

Alternatively, when the third priority is equal to the fourth priority, the terminal device may continue to select an appropriate relay device according to the level of the first priority and the second priority.

In one possible implementation, the terminal apparatus #1 may acquire the first priority information to the fourth priority information. When the terminal device #1 determines to reduce the load of the access network device, the terminal device #1 may preferentially select the relay device according to the first priority information and the second priority information, and select the relay device according to the third priority information and the fourth priority information when a suitable relay device cannot be selected according to the first priority information and the second priority information; when the terminal apparatus #1 determines to reduce the load of the relay apparatus, the terminal apparatus #1 may preferentially select the relay apparatus according to the third priority information and the fourth priority information, and perform selection according to the first priority information and the second priority information in a case where a suitable relay apparatus cannot be selected according to the third priority information and the fourth priority information.

In addition, when the suitable relay device cannot be determined according to the first threshold value and the second threshold value, the suitable relay device may continue to be selected according to the first priority level to the fourth priority level.

The scheme proposed in the present application is described in detail below with reference to fig. 3, and the scheme shown in fig. 3 can be applied to the communication system shown in fig. 1.

S301, the access network device #1 transmits fourth information to the relay device #1 within its service range, where the fourth information indicates the relay selection policy #1 corresponding to the access network device #1. Accordingly, the relay apparatus #1 receives the fourth information.

The access network apparatus #2 transmits, to the relay apparatus #2 within its service range, fifth information indicating the relay selection policy #2 corresponding to the access network apparatus #2. Accordingly, the relay apparatus #2 receives the fifth information.

In one possible implementation, the access network apparatus #1 may transmit the fourth information to the relay apparatus #1 by broadcasting. The access network device #2 may transmit the fifth information to the relay device #2 in a broadcast manner.

In another possible implementation manner, when the relay device #1 and the access network device #1 are in an RRC connected state, the access network device #1 may send the fourth information to the relay device #1 through RRC signaling. When the relay device #2 and the access network device #2 are in the RRC connected state, the access network device #2 may transmit the fifth information to the relay device #2 through RRC signaling.

The relay selection policy #1 and the relay selection policy #2 will be explained below.

Case 1:

the relay selection policy #1 applies to all relay devices within the service range of the access network device #1. The relay selection policy #2 applies to all relay devices within the service range of the access network device #2.

Case 2:

relay selection policy #1 includes M relay selection policies, and geographical location range information to which each relay selection policy applies. It should be understood that the area served by access network equipment #1 may be divided into M geographical location ranges, each having its corresponding relay selection policy, M being greater than or equal to 2.

For example, relay selection policy #1 includes the information in table 1.

TABLE 1

Relay selection policy #11	Geographic location Range #11
		Relay selection strategy #12	Geographic location Range #12
Relay selection strategy #13	Geographic location Range #13

Similarly, relay selection policy #2 includes M relay selection policies, and geographical location range information to which each relay selection policy applies.

For example, relay selection policy #2 includes the information in table 2.

TABLE 2

Relay selection strategy #21	Geographic location Range #21
		Relay selection strategy #22	Geographic location Range #22
Relay selection policy #23	Geographic location Range #23

Case 3:

the access network device #1 determines the geographical position of the relay device #1, and transmits a relay selection policy to be applied to the relay device #1.

For example, as shown in table 1, the access network device #1 determines that the geographical position of the relay device #1 is within the geographical position range #11, and the access network device #1 transmits the relay selection policy #11 to the relay device #1.

Similarly, access network device #2 determines the geographical location of relay device #2, and transmits to relay device #2 the relay selection policy applicable by relay device #2.

For example, as shown in table 2, the access network device #2 determines that the geographical position of the relay device #2 is within the geographical position range #21, and the access network device #2 transmits the relay selection policy #21 to the relay device #2.

S302, the access network device #1 sends the first threshold information to the first terminal device within its service range. Accordingly, the first terminal device receives the first threshold information.

It should be understood that the function of the first threshold is as described above and will not be described in detail herein.

In one possible implementation, when the step S301 is performed according to the case 2, the method further includes: s303, the relay device #1 determines a relay selection policy to be applied to the relay device #1, according to the geographical location of the relay device #1.

Relay device #2 determines a relay selection policy to be applied by relay device #2, based on the geographical location of relay device #2.

S304, the relay device #1 transmits a first discovery message including the first indication information. The first indication information indicates a relay selection policy applicable by the relay device #1, the relay selection policy including a first threshold value. In one possible implementation, the relay selection policy may further include the first priority and/or the third priority.

The relay device #2 transmits a second discovery message including the second indication information. The second indication information indicates a relay selection policy applicable by the relay apparatus #2, the relay selection policy including a second threshold value. In one possible implementation, the relay selection policy may further include a second priority and/or a fourth priority.

The first priority to the fourth priority, the first threshold value and the second threshold value are as described above, and a description thereof will not be provided.

In one possible implementation, the first discovery message may include a first reference signal, and the second discovery message may include a second reference signal.

S305, when the power of the third reference signal transmitted by the access network device #1 received by the terminal device #1 is smaller than the first threshold, the terminal device #1 may initiate a process of selecting a relay device.

Terminal apparatus #1 has received the first discovery message transmitted by relay apparatus #1 and the second discovery message transmitted by relay apparatus #2. The first discovery message includes first indication information, and the second discovery message includes second indication information.

When the received power #1 is smaller than or equal to the first threshold value and the received power #2 is larger than the second threshold value, the terminal device may establish a sidelink connection with the relay device #2.

According to the scheme of the application, before judging whether the terminal equipment can be accessed to the network through a certain relay equipment, the terminal equipment firstly determines the relay selection strategy applicable to the relay equipment. In contrast, if the relay selection policy used by the terminal device is not applicable to the relay device, even if a sidelink connection is established between the terminal device and the relay device, the communication quality of the sidelink connection may not achieve the expected effect, which may affect the user experience on the one hand, and also cause a certain signaling waste (the sidelink connection may need to be reestablished) on the other hand. Therefore, by adopting the scheme of the application, after the side link connection is established between the terminal equipment and the relay equipment, the communication quality between the terminal equipment and the relay equipment can achieve the expected effect, so that a user can have better experience, and the signaling overhead can be saved to a certain extent.

According to the foregoing method, fig. 4 is a communication device provided in this embodiment, where the communication device includes a transceiving unit 401 and a processing unit 402. The transceiving unit 401 may be used to implement the receiving and transmitting functions in the method embodiments. Other functions in method embodiments may be implemented by the processing unit 402. The transceiving unit can be realized by an input interface and an output interface in the data processing chip, and the sending and receiving in the method embodiment respectively correspond to the output and the input in the chip. The transceiver unit 401 may also be split into a receiving unit and a sending unit, where the receiving unit may be configured to implement the receiving function in the method embodiment, and the sending unit may be configured to implement the sending function in the method embodiment. The receiving unit may be implemented by an output interface in the data processing chip, and the transmitting unit may be implemented by an input interface of the data processing chip. In addition, the transceiver and the processing unit may be implemented by the same chip, and the present application is not limited herein. It should be understood that the transceiver unit 401 in the embodiment of the present application may also be implemented by a transceiver (including a transmitter and a receiver) or a transceiver-related circuit component, and the processing unit 402 may also be implemented by a processor or a processor-related circuit component (or referred to as a processing circuit).

Illustratively, when the communication device is a terminal device, the transceiving unit 401 and the processing unit 402 can support the actions performed by the terminal device in the above method examples. For example, the transceiver 401 may perform the receiving of the first information in the above method embodiment, and other processes in the technical solutions described herein; processing unit 402 may perform the process of initiating selection of a relay device, as well as other processes in the aspects described herein.

Illustratively, when the communication device is an access network device, the transceiving unit 401 and the processing unit 402 can support the actions performed by the access network device in the above method example. For example, the transceiver unit 401 may complete the obtaining of the relay selection policy and the corresponding application range of the neighboring access network device in the foregoing method embodiment, and other processes in the technical solution described herein.

Illustratively, when the communication device is a relay device, the transceiving unit 401 and the processing unit 402 can support the actions performed by the relay device in the above method example. For example, the transceiver 401 may complete the first discovery message, the second discovery message, and other processes in the technical solutions described herein in the above method embodiments; processing unit 402 may perform the determination of applicable relay selection strategies, as well as other processes in the solutions described herein.

An embodiment of the present application further provides a communication apparatus, as shown in fig. 5, including: a processor 501, a communication interface 502, and a memory 503. The processor 501, the communication interface 502, and the memory 503 may be connected to each other through a bus 505; the bus 505 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus 505 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in FIG. 5, but this is not intended to represent only one bus or type of bus. The processor 501 may be a Central Processing Unit (CPU), a Network Processor (NP), or a combination of a CPU and an NP. The processor may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a Programmable Logic Device (PLD), or a combination thereof. The PLD may be a Complex Programmable Logic Device (CPLD), a field-programmable gate array (FPGA), a General Array Logic (GAL), or any combination thereof. The memory 503 may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The non-volatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. Volatile memory can be Random Access Memory (RAM), which acts as external cache memory.

The processor 501 is used to implement data processing operations of the communication apparatus. The communication interface 502 is used to implement a transceiving operation of the communication apparatus.

Illustratively, when the communication device is a terminal device, the processor 501, the communication interface 502, and the memory 503 can support the actions performed by the terminal device in the above method examples. For example, the communication interface 502 may perform the receiving of the first information in the above method embodiments, and other processes in the technical solutions described herein; processor 501 may perform the process of initiating selection of a relay device, as well as other processes in the solutions described herein.

Illustratively, when the communication device is an access network device, the processor 501, the communication interface 502, and the memory 503 can support the actions performed by the access network device in the above method examples. For example, the communication interface 502 may complete the obtaining of the relay selection policy and the corresponding application range of the neighboring access network device in the foregoing method embodiment, as well as other processes in the technical solutions described herein.

Illustratively, when the communication device is a relay device, the processor 501, the communication interface 502, and the memory 503 can support the actions performed by the relay device in the above-described method examples. For example, the communication interface 502 may perform the above method embodiments to transmit the first discovery message, the second discovery message, and other processes in the technical solutions described herein; the processor 501 may perform the determination of an applicable relay selection policy, as well as other processes within the teachings described herein.

The technical scheme of the embodiment of the application can be applied to various communication systems, for example: a global system for mobile communication (GSM) system, a Code Division Multiple Access (CDMA) system, a Wideband Code Division Multiple Access (WCDMA) system, a General Packet Radio Service (GPRS), a long term evolution (long term evolution, LTE) system, a LTE Frequency Division Duplex (FDD) system, a LTE Time Division Duplex (TDD) system, a universal mobile telecommunication system (universal mobile telecommunication system, UMTS), a Worldwide Interoperability for Microwave Access (WiMAX) communication system, a future fifth generation (5, g) system, or a new radio Network (NR), etc.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A relay selection method, comprising:

the first terminal equipment determines a first relay selection strategy applicable to the first relay equipment;

and the first terminal equipment determines whether to establish side link connection with the first relay equipment according to the first relay selection strategy.

2. The method of claim 1,

the method further comprises the following steps:

the first terminal equipment acquires first information, wherein the first information indicates N relay selection strategies and N application ranges, the N application ranges correspond to the N relay selection strategies one by one, and N is a positive integer;

the first terminal equipment acquires second information from the first relay equipment, wherein the second information comprises position information of the first relay equipment;

the first terminal device determines a first relay selection strategy applicable to a first relay device, and the method comprises the following steps:

and the first terminal equipment determines the first relay selection strategy in the N relay selection strategies according to the second information, wherein the position of the first relay equipment is within an application range corresponding to the first relay selection strategy.

3. The method of claim 1,

the method further comprises the following steps:

the first terminal equipment acquires first indication information from the first relay equipment, wherein the first indication information comprises information of the first relay selection strategy;

and the first terminal equipment determines the first relay selection strategy according to the first indication information.

4. The method according to any one of claims 1 to 3,

the method further comprises the following steps:

the first terminal equipment determines a second relay selection strategy applicable to second relay equipment;

and the first terminal equipment determines whether to establish side link connection with the second relay equipment according to the second relay selection strategy.

5. The method of claim 4,

the first relay selection strategy comprises a first threshold value, and the second relay selection strategy comprises a second threshold value;

the method further comprises the following steps:

the first terminal device receiving a first discovery message from the first relay device and a second discovery message from the second relay device;

the determining whether to establish a sidelink connection with the first relay device and the determining whether to establish a sidelink connection with the second relay device includes:

when the received power of the first discovery message is greater than the first threshold value and the received power of the second discovery message is less than or equal to the second threshold value, the first terminal device determines to establish a side link connection with the first relay device;

and when the receiving power of the first discovery message is smaller than or equal to the first threshold value and the receiving power of the second discovery message is larger than the second threshold value, the first terminal equipment determines to establish a side link connection with the second relay equipment.

6. The method of claim 5,

the first relay selection policy further comprises a first priority, and the second relay selection policy further comprises a second priority;

in case the received power of the first discovery message is greater than the first threshold value and the received power of the second discovery message is greater than the second threshold value,

when the first priority is higher than the second priority, the first terminal device determines to establish a sidelink connection with the first relay device;

and when the first priority is lower than the second priority, the first terminal equipment determines to establish a side link connection with the second relay equipment.

7. The method of claim 6,

the first priority is associated with a load of a first access network device and the second priority is associated with a load of a second access network device;

wherein the first relay device is within a service range of the first access network device and the second relay device is within a service range of the second access network device.

8. A terminal device, comprising:

a transceiving unit and a processing unit;

the processing unit is used for determining a first relay selection strategy applicable to the first relay equipment;

the processing unit is further configured to determine whether to establish a sidelink connection with the first relay device according to the first relay selection policy.

9. The apparatus of claim 8,

the receiving and sending unit is configured to acquire first information, where the first information indicates N relay selection policies and N application ranges, where the N application ranges correspond to the N relay selection policies one to one, and N is a positive integer;

the transceiver unit is further configured to acquire second information from the first relay device, where the second information includes location information of the first relay device;

the processing unit is configured to determine a first relay selection policy applicable to a first relay device, and includes:

the processing unit determines the first relay selection strategy from the N relay selection strategies according to the second information, wherein the position of the first relay device is within an application range corresponding to the first relay selection strategy.

10. The apparatus of claim 8,

the transceiver unit is configured to acquire first indication information from the first relay device, where the first indication information includes information of the first relay selection policy;

the processing unit determines the first relay selection strategy according to the first indication information.

11. The apparatus according to any one of claims 8-10,

the processing unit is further configured to determine a second relay selection policy applicable to a second relay device;

the processing unit is further configured to determine whether to establish a sidelink connection with the second relay device according to the second relay selection policy.

12. The apparatus of claim 11,

the transceiver unit is further configured to receive a first discovery message from the first relay device and a second discovery message from the second relay device;

when the received power of the first discovery message is greater than the first threshold value and the received power of the second discovery message is less than or equal to the second threshold value, the processing unit determines to establish a sidelink connection with the first relay device;

when the received power of the first discovery message is smaller than or equal to the first threshold and the received power of the second discovery message is larger than the second threshold, the processing unit determines to establish a sidelink connection with the second relay device.

13. The apparatus of claim 12,

when the first priority is higher than the second priority, the processing unit determines to establish a sidelink connection with the first relay apparatus;

when the first priority is lower than the second priority, the processing unit determines to establish a sidelink connection with the second relay apparatus.

14. The apparatus of claim 13,

15. A communication device, comprising: a processor and memory, the processor for executing computer programs or instructions stored in the memory to cause the communication device to perform the method of any of claims 1-7.

16. A computer-readable storage medium comprising a computer program or instructions which, when run on a computer, cause the computer to carry out the method of any one of claims 1 to 7.

17. A chip system, comprising: at least one processor for executing a computer program or instructions in a memory such that the method of any of claims 1-7 is implemented.