Patent Description:
On one hand, with the development of wireless multimedia services, demands of people for high data rate and user experience are gradually increased and higher requirements are raised to system capacity and coverage of traditional cellular networks. On the other hand, application scenarios such as public security, social network, short-distance data share and local advertisement cause demands of people for Proximity Services (ProSe) such as understanding nearby people or things and communicating therewith to be gradually increased. Traditional cellular networks centered on base stations have obvious limitations in aspects such as high data rate and support of proximity services, and a Device-to-Device (D2D) technology, which represents a new development direction of future communication technologies, emerges at the right moment under the background of these demands. The application of the D2D technology can reduce the burden of the cellular networks, decrease the battery power consumption of the user equipment, improve data rate, improve the robustness of network infrastructure and very well satisfy the requirements on the high data rate and proximity services. Current D2D is also called as ProSe or Sidelink Transmission.

The D2D technology can work on licensed bands or unlicensed bands and allow a plurality of user equipment supporting D2D functions, i.e., D2D User Equipment (D2D UE, also called as ProSe enabled UE) to perform direct discovery/direct communication under a situation that there is network infrastructure or there is no network infrastructure. Application scenarios of D2D mainly include three scenarios. <FIG> illustrates a schematic view of related D2D application scenarios. As illustrated in <FIG>, in scenario <NUM>, user equipment perform data interaction under the coverage of a cellular network and user plane data do not pass through network infrastructure; in scenario <NUM>, UE in areas with weak/no coverage perform relay transmission, user equipment (such as UE4 illustrated in <FIG>) with poor signal quality is allowed to communicate with a network through other adjacent user equipment (such as UE3) under network coverage, thereby operators are helped to expand the coverage and improve the capacity; and in scenario <NUM>, devices directly communicate with one another, it mainly applied to situations such as earthquakes or emergencies when the cellular network cannot work normally, and for example, control planes and user planes between UE5, UE6 and UE7 perform one-hop or multi-hop data communication without passing through network infrastructure.

The D2D technology usually includes a D2D discovery technology and a D2D communication technology, herein the D2D discovery technology refers to a technology which is used for judging/determining whether user equipment are proximal. For related methods, D2D user equipment in scenario <NUM> discover each other mainly by sending or receiving discovery signals/information, and in scenario <NUM> and scenario <NUM>, no corresponding solution is determined, i.e., no relay node selection solution is given. A technical literature <NPL>, discusses about relay for public safety ProSe. <CIT> introduces about a method for D2D relay link selection in a LTE based access network. A technical literature <NPL>, discusses about relaying for D2D proximity services.

The following is a summary of a subject described in detail in this text. However, the summary is not used for limiting the protection scope of the claims.

As compared with the related art, the technical solution provided by an embodiment of the present invention includes that: a network control node receives relay-related information sent by user equipment and determines a relay node; and the network control node sends device-to-device communication relay configuration information to the determined relay node. According to the embodiment of the present invention, by sending the relay-related information in a network to perform selection or configuration of a relay node, a corresponding solution is provided for a scenario for which relay selection is not provided, and thereby the selection of the relay node is realized.

After reading and understanding the drawings and the detailed description, other aspects may be understood.

An embodiment of the present application will be described below in detail with reference to the drawings. It needs to be stated that embodiments in the present application and the features in an embodiment may be mutually and freely combined under a situation of no conflict.

<FIG> illustrates a flowchart of a method for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the method includes the following steps:
In step <NUM>, the user equipment sends relay-related information used for determining a relay node to a network control node.

In this step, the relay-related information includes:.

In an embodiment of the present invention, the network control node includes: a base station and/or a network element having a ProSe function and/or other network elements executing a device-to-device communication relay selection function.

When the relay-related information includes the relay usable time period of the user equipment, the relay usable time period of the user equipment includes: a time period at which the user equipment is usable for device-to-device communication relay;.

When the relay-related information includes the relay seeking information sent by user equipment seeking the relay node monitored by the user equipment,
the relay seeking information sent by user equipment seeking the relay node monitored by the user equipment includes:.

Alternatively, when the relay-related information includes the type of the user equipment seeking the relay node,.

When the relay-related information includes the traffic and service quality demands of the user equipment seeking the relay node, the relay-related information further includes:
a guaranteed bitrate, and/or guaranteed maximum bitrate, and/or guaranteed average bitrate, and/or overall traffic, and/or service quality type indication and/or priority corresponding to a service flow which needs to be relay-forwarded by the user equipment seeking the relay node.

Before this step, the method further includes the following step,.

The user equipment receives request information, sent by the network control node, of the relay-related information or report configuration information of the relay-related information, and the user equipment sends the relay-related information according to the request information of the relay-related information or the report configuration information of the relay-related information.

In step <NUM>, if the user equipment is determined as a relay node, the user equipment receives device-to-device communication relay configuration information sent by the network control node.

In this step, the device-to-device communication relay configuration information includes:.

Before the user equipment sends the relay-related information to the network control node, the method provided by an embodiment of the present invention further includes the following steps:.

After the user equipment determined as a relay node receives the device-to-device communication relay configuration information sent by the network control node, the method provided by an embodiment of the present invention further includes the following steps.

The user equipment executes activation and/or setup, release and/or deactivation or modification of a relay function of the determined relay node according to the device-to-device communication relay configuration information.

<FIG> illustrates a flowchart of another method for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the method includes the following steps.

In step <NUM>, a network control node receives relay-related information sent by user equipment and determines a relay node.

In this step, the operation of determining a relay node includes the following operation.

The network control node performs the relay node selection or configuration according to the relay-related information and determines user equipment which is selected or configured as a relay node as the relay node.

Alternatively, when the relay-related information includes the relay usable time period of the user equipment, the relay usable time period of the user equipment includes: a time period at which the user equipment is usable for device-to-device communication relay;.

It needs to be stated that the moving speed indication generally includes high, medium, low and other graded moving speed indications set according to experience of one skilled in the art, and specific grades may be set according to the actual situations.

When the relay-related information includes the relay transmitting-receiving capability of the user equipment,.

It needs to be stated that the relay forwarding load indication of the user equipment here refers to high, medium, low and other load indications determined according to experience of one skilled in the art and defined according to load standards.

When the relay-related information includes the relay information sent by the relay node monitored by the user equipment, the relay information sent by the relay node monitored by the user equipment includes:.

When the relay-related information includes the type of the user equipment seeking the relay node,.

Before the network control node receives the relay-related information sent by the user equipment, the method provided by an embodiment of the present invention further includes the following step:
the network control node sends request information of the relay-related information or report configuration information of the relay-related information to the user equipment.

The report configuration information of the relay-related information includes that: the report of the relay-related information is event report or periodic report and one or more relay-related information needs to be reported.

In step <NUM>, the network control node sends device-to-device communication relay configuration information to the user equipment determined as the relay node.

After the network control nodes sends the device-to-device communication relay configuration information to the user equipment selected as the relay node, the method provided by an embodiment of the present invention further includes the following steps:.

Before the network control node receives the relay-related information sent by the user equipment, the method provided by an embodiment of the present invention further includes the following steps.

The user equipment receives a relay reception resource pool sent or preconfigured by the network control node through broadcasting; and
the user equipment monitors the relay reception resource pool and receives relay information sent by adjacent relay nodes or relay node seeking information sent by adjacent user equipment.

Before the network control node receives the relay-related information sent by the user equipment, the method provided by an embodiment of the present invention further includes the following step:.

After the network control node receives the relay-related information sent by the user equipment, the method provided by an embodiment of the present invention further includes the following steps.

The network control node randomly selects or releases a relay node from user equipment supporting device-to-device communication relay; or.

It needs to be stated that the change of relay-related information refers to change in the relay-related information, such as change in the relay load state, and/or the monitored information of the user equipment seeking the relay, the mobility state reported by the user equipment configured as the device-to-device communication relay node, and/or the remaining power level.

In step <NUM>, user equipment receives relay-related information.

Before the user equipment receives relay-related information, the method provided by an embodiment of the present invention further includes the following steps.

The user equipment receives a relay reception resource pool and/or relay threshold information sent or preconfigured by a network control node through broadcasting; and.

In step <NUM>, the user equipment selects or configures the user equipment as a relay node.

It needs to be stated that selecting or configuring as a relay node is actually determining as a relay node.

In this step, the operation of selecting or configuring the user equipment as a relay node includes the following operations.

The user equipment monitors the relay reception resource pool and judges whether there is relay-related information sent by adjacent relay nodes; and if there is the relay-related information, it receives the relay-related information sent by adjacent relay nodes; and.

When the user equipment receives the relay-related information, the method provided by an embodiment of the present invention further includes the following steps.

The user equipment monitors the relay reception resource pool and judges whether there is relay seeking information sent by adjacent user equipment; and if there is relay seeking information, it receives relay node seeking information sent by adjacent user equipment; and the user equipment selects or configures the user equipment as a relay node according to the monitored relay node seeking information sent by the adjacent user equipment.

If the user equipment selects or configures the user equipment as a relay node, the method provided by an embodiment of the present invention further includes the following steps.

The user equipment selects or releases a relay function of the user equipment according to a predefined rule and the received relay-related information,
herein the predefined rule includes that:.

Before the user equipment configures or releases the relay function of the user equipment, the method provided by an embodiment of the present invention further includes the following steps.

A network control node sends the relay judgment information as the predefined rule to the user equipment through broadcasting or dedicated signaling,.

It needs to be stated that determining the geographical location requirement according to whether a measurement value of measurement performed by the user equipment to the RSRP of the serving cell and/or the adjacent cell satisfies a given threshold is one of determination methods, and other methods which can be used for determining the geographical location requirement may also be applied to an embodiment of the present invention.

After the user equipment selects or configures a relay node, the method provided by an embodiment of the present invention further includes the following step: a relay configuration performed by a network control node to the user equipment is capable of overlaying an autonomous relay configuration of the user equipment.

In step <NUM>, the user equipment sends an access relay request containing relay-related information to a network control node.

In an embodiment of the present invention, the access relay includes: a device-to-device communication relay device having a relay function and capable of forwarding data for the user equipment.

The access relay request includes: an access relay node configuration request, and/or an access relay node release request and/or an access relay node update request.

The access relay request includes:
a requested relay type, the requested number of access relay nodes, a device-to-device communication group to which the user equipment belongs, a geographical location of the user equipment, and relay-related information, sent by a monitored relay node, of the relay node.

When the access relay request is an access relay node release request or an access relay node update request,
the access relay request further includes configured access relay node identification information.

When the relay-related information is obtained by monitoring information sent by a relay node,
the relay-related information sent by the relay node includes:.

The operation of obtaining the relay-related information by monitoring information sent by the relay node includes the following operations.

The user equipment receives a relay reception resource pool sent or preconfigured by the network control node through broadcasting or dedicated signaling; and
the user equipment monitors the relay reception resource pool and acquires the relay-related information sent by the relay node.

When the user equipment is not capable of acquiring the relay-related information sent by the relay node by monitoring the relay reception resource pool, the method provided by an embodiment of the present invention further includes the following steps.

In step <NUM>, the user equipment receives an access relay configuration sent by the network control node.

The access relay configuration includes: a relay identification of the access relay node, and configuration of activation and/or setup, release and/or deactivation or modification of the access relay node.

After the user equipment receives the access relay configuration sent by the network control node, the method further includes the following step.

The user equipment executes configured activation and/or setup, release and/or deactivation or modification of the access relay node according to the access relay configuration.

In step <NUM>, a network control node receives an access relay request containing relay-related information sent by user equipment.

In this step, the access relay request includes:
an access relay node configuration request, and/or an access relay node release request and/or an access relay node update request.

The access relay request includes:
a requested relay type, and/or the requested number of access relay nodes, and/or a device-to-device communication group to which the user equipment belongs, and/or a geographical location of the user equipment, and/or relay-related information, sent by a monitored relay node, of the relay node.

When the access relay request is an access relay node release request or an access relay node update request,
the access relay request further includes: configured access relay node identification information.

When the relay-related information is obtained by monitoring information sent by a relay node,
the relay-related information includes:.

When the user equipment is not capable of acquiring the relay-related information sent by the relay node through broadcasting by monitoring the relay reception resource pool, the method further includes the following steps.

The user equipment sends a relay discovery message through broadcasting; and
after an adjacent relay node monitors the relay discovery message, the relay-related information is sent to the user equipment.

In step <NUM>, the network control node sends an access relay configuration to the user equipment.

In this step, the access relay includes: a device-to-device communication relay device having a relay function and capable of forwarding data for the user equipment.

The access relay configuration includes: a relay identification of the access relay node, configuration of activation and/or setup, release and/or deactivation or modification of the access relay node, and/or device-to-device communication transmission and reception resource configuration.

After the network control node sends the configuration of the access relay node to the user equipment, the method provided by an embodiment of the present invention further includes the following step.

The user equipment executes configured activation and/or setup, release and/or deactivation or modification of the access relay node according to the access relay node configuration.

Before this step, the method provided by an embodiment of the present invention further includes the following step:
the network control node judges a relay node adjacent to the user equipment according to the geographical location of the user equipment and acquires the relay-related information corresponding to the adjacent relay node.

The operation of acquiring the relay-related information corresponding to the adjacent relay node includes the following operation.

The network control node requests the relay node to send the relay-related information through broadcasting or send the relay-related information through dedicated signaling, such that the network control node acquires the relay-related information corresponding to the adjacent relay node.

Before the network control node sends the access relay node configuration to the user equipment, the method provided by an embodiment of the present invention further includes the following step.

The network control node selects or configures an access relay node for the user equipment according to the relay-related information.

The operation that the network control node selects or configures an access relay node for the user equipment according to the relay-related information includes the following operations.

When the access relay request received by the network control node and sent by the user equipment is a relay release request, the network control node releases the access relay configuration of the user equipment; and
when the access relay request received by the network control node and sent by the user equipment is a relay update request, a relay type requested by the user equipment is judged, a set of relay nodes corresponding to the relay type and adjacent to the user equipment is found out, and an access relay node is randomly selected for the user equipment; or the network control node configures or reconfigures one or more access relay nodes for the user equipment according to a predefined rule and relay-related information of the relay node.

It needs to be stated that the predefined rule refers to a rule predefined according to experience of one skilled in the art, such as that the remaining power level is high, and/or the mobility state is low; and/or the geographical location is adjacent to the user equipment; and/or the processing capability is strong/the charging requirement is low, and/or the cellular and device-to-device communication service traffic is low, and/or the relay load is low, and/or the relay access forbidden state is a non-forbidden state, and/or the relay node has a PLMN/D2D group consistent with the user equipment.

<FIG> illustrates a flowchart of another method for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the method includes the following steps:
In step <NUM>, the user equipment receives relay-related information sent by an adjacent relay node.

Before this step, the method further includes the following steps.

The user equipment receives a relay reception resource pool and/or a relay selection threshold sent or preconfigured by a network control node through broadcasting or dedicated signaling,.

When the user equipment is not capable of receiving the relay-related information sent by the relay node by monitoring the relay reception resource pool, the method provided by an embodiment of the present invention further includes the following steps.

In step <NUM>, the user equipment selects or configures an access relay node.

Before this step, the method provided by an embodiment of the present invention further includes the following step:
the user equipment selects or configures an access relay node according to the relay-related information.

The operation that the user equipment selects or configures an access relay node includes the following operation.

The user equipment configures/reconfigures one or more relay access nodes according to a predefined rule and acquired relay-related information.

Alternatively, when the user equipment has not selected an access relay node, the user equipment judges whether a measurement result of the relay-related information sent to the relay node is greater than a relay selection minimum device-to-device communication link quality threshold, and if the measurement result is less than the relay selection minimum device-to-device communication link quality threshold, the relay node is excluded; and
when the user equipment has already selected an access relay node, the user equipment adds a relay reselection hysteresis value to the measurement value of the selected access relay node, then ranks the measurement value added with the relay reselection hysteresis value and measurement results of all other monitored relay nodes, and reselects a relay node ranked at the topmost place.

It needs to be stated that, if judgment is made according to a plurality of predefined rules, the judgment sequence may be set according to experience of one skilled in the art. For example, the user equipment having a device-to-device communication relay function and having a relay intention/interest/indication is set as a first judgment rule, the remaining power level being high or low is set as a second judgment rule, etc., and the specific rules may be added or adjusted according to the actual situations.

Before the user equipment configures or reconfigures the access relay node according to the predefined rule and the relay-related information of the user equipment, the method further includes the following step.

The network control node sends relay judgment information of access relay node to the user equipment through broadcasting or dedicated signaling to determine the predefined rule,
herein the relay judgment information includes: information about a remaining power level requirement of relay node, and/or a geographical location requirement of relay node, and/or a cellular link quality requirement of relay node , and/or a mobility state requirement of relay node, and/or a processing capability requirement, and/or a cellular and device-to-device communication service traffic requirement and/or a load requirement of relay node.

When the relay judgment information includes a cellular link quality requirement of relay node, the cellular link quality requirement of relay node is determined according to whether a signal measurement value of measurement performed by the relay node to a serving cell satisfies a given threshold.

When the relay judgment information includes a geographical location requirement of relay node, the geographical location requirement of relay node is determined according to whether a signal measurement value of measurement performed by the user equipment to the relay-related information of the relay node satisfies a given threshold.

After the user equipment selects or configures an access relay node according to the relay-related information of the user equipment, the method provided by an embodiment of the present invention further includes the following step.

An access relay node configuration performed by the network control node to the user equipment is capable of overlaying an access relay node configuration of the user equipment.

An embodiment of the present invention further provides a computer storage medium, storing computer-executable instructions used for executing the methods.

<FIG> illustrates a structural diagram of netwok control node for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>,.

The user equipment provided by an embodiment of the present invention further includes a second receiving unit configured to receive request information, sent by the network control node, of the relay-related information or report configuration information of the relay-related information, herein, when the request information of the relay-related information or the report configuration information of the relay-related information is received, the first sending unit sends the relay-related information.

The user equipment provided by an embodiment of the present invention further includes a resource pool monitoring unit configured to receive a relay reception resource pool sent or preconfigured by the network control node through broadcasting, monitor the relay reception resource pool and/or relay threshold and receive relay information sent by adjacent relay nodes or relay node seeking information sent by adjacent user equipment.

The user equipment provided by an embodiment of the present invention further includes a relay processing unit configured to execute activation and/or setup, release and/or deactivation or modification of a relay function of the determined relay node according to the device-to-device communication relay configuration information.

<FIG> illustrates a structural diagram of a network control node for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the network control node includes: a relay determination unit and a third sending unit, herein,.

The relay determination unit is configured to receive the relay-related information sent by the user equipment, perform the relay node selection or configuration according to the relay-related information and determine the user equipment selected or configured as a relay node as a relay node.

The network control node provided by an embodiment of the present invention further includes a fourth sending unit configured to, before the network control node receives the relay-related information sent by the user equipment, send request information or report configuration information of the relay-related information to the user equipment.

The network control node provided by an embodiment of the present invention further includes a resource pool unit configured to, before the relay determination unit receives the relay-related information sent by the user equipment,
send or preconfigure a relay reception resource pool and/or a relay threshold to the user equipment through broadcasting, such that the user equipment monitors the relay reception resource pool and receives relay advertisement information sent by other relay nodes or information sent by other user equipment about finding user equipment determined as a relay node.

The network control node provided by an embodiment of the present invention further includes a selection and release unit configured to, after the relay determination unit receives the relay-related information sent by the user equipment,.

<FIG> illustrates a structural diagram of another piece of user equipment for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the user equipment includes: a fifth receiving unit and a determination unit, herein,.

The user equipment further includes a resource pool monitoring unit configured to receive a relay reception resource pool and/or a relay threshold sent or preconfigured by a network control node through broadcasting, monitor the relay reception resource pool and receive relay information sent by adjacent relay nodes or the relay node seeking information sent by adjacent user equipment; and
the determination unit is configured to, when the monitoring unit does not receive the relay-related information sent by the adjacent user equipment or a received relay type sent by the adjacent user equipment is not a relay type supported by the user equipment, select or configure the user equipment as a relay node.

The resource pool monitoring unit is further configured to monitor the relay reception resource pool and judge whether there is relay user equipment finding information sent by adjacent user equipment; and
the determination unit is configured to, when the monitoring unit receives the relay node seeking information sent by the adjacent user equipment, select or configure the user equipment as a relay node; or configure the user equipment as a relay node according to a predefined rule and the received relay-related information.

The user equipment provided by an embodiment of the present invention further includes a relay processing unit configured to select or configure the user equipment as a relay node, and.

The user equipment provided by an embodiment of the present invention further includes a relay judgment receiving unit configured to, before the user equipment selects or releases the relay function of the user equipment, receive relay judgment information sent by the network control node through broadcasting or dedicated signaling and send the relay judgment information as the predefined rule to the relay processing unit,.

<FIG> illustrates a structural diagram of another piece of user equipment for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the user equipment includes:.

The user equipment provided by an embodiment of the present invention further includes a monitoring and acquisition unit configured to acquire relay-related information sent by a relay node by monitoring a relay reception resource pool; and
when the user equipment is not capable of acquiring the relay-related information sent by the relay node by monitoring the relay reception resource pool, send a relay discovery message, such that an adjacent relay node sends the relay-related information to the user equipment after the adjacent relay node monitors the relay discovery message.

The user equipment provided by an embodiment of the present invention further includes an access relay processing unit configured to execute configured activation and/or setup, release and/or deactivation or modification of an access relay node according to an access relay node configuration.

<FIG> illustrates a structural diagram of another network control node for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the network control node includes: a seventh receiving unit and a seventh sending unit, herein,.

The network control node provided by an embodiment of the present invention further includes a resource pool broadcasting unit configured to send or preconfigure a relay reception resource pool to the user equipment through broadcasting or dedicated signaling, such that the user equipment monitors the relay reception resource pool and/or acquires relay-related information sent by a relay node according to the relay selection threshold,
herein the relay configuration request includes relay-related information, sent by a monitored relay node, of the relay node.

The network control node provided by an embodiment of the present invention further includes an acquisition unit configured to judge a relay node adjacent to the user equipment according to a geographical location of the user equipment and acquire relay-related information corresponding to the adjacent relay node, so as to acquire the relay-related information of the adjacent relay node.

The network control node provided by an embodiment of the present invention further includes a relay determination unit configured to select or configure user equipment as an access relay node according to the relay-related information. The relay determination unit is further configured to, when the access relay request received by the sixth receiving unit and sent by the user equipment is a relay release request, release the access relay configuration of the user equipment; and.

<FIG> illustrates a structural diagram of another piece of user equipment for realizing device-to-device communication relay selection according to an embodiment of the present invention. As illustrated in <FIG>, the user equipment includes: an eighth receiving unit and a determination unit, herein,.

The user equipment provided by an embodiment of the present invention further includes a ninth receiving unit and a monitoring unit, herein,.

The user equipment provided by an embodiment of the present invention further includes a relay discovery unit configured to, when the sixth receiving unit is not capable of receiving the relay-related information sent by the relay node by monitoring the relay reception resource pool, send a relay discovery message through broadcasting, such that the user equipment monitors the relay-related information sent by the relay node.

The determination unit is configured to select or configure an access relay node according to the relay-related information.

The determination unit is configured to configure/reconfigure one or more relay access nodes according to the relay selection threshold, a predefined rule and acquired relay-related information.

The methods provided by the present invention will be clearly described below in detail through specific embodiments. An embodiment is not used for limiting the protection scope of the present invention. The technical problem to be solved by an embodiment of the present invention is a relay selection problem of UE-to-network relay and UE-to-UE relay in a device-to-device communication system. An embodiment gives specific possible relay and access relay node selection methods and related signaling processes.

Embodiment <NUM> to embodiment <NUM> describe processes that a base station and user equipment select a relay node or autonomously judge whether to become a relay node.

Officer A, B, C and D (Officer A, B, C and D generally refer to working personnel using user equipment) respectively use public security user equipment UE1, UE2, UE3 and UE4 having a D2D function. Officer A, B, C and D all subscribe to public security services. At a rescue place, UE1 and UE2 are in a state of being covered by a network and UE3 and UE4 are not covered by a network. In consideration of that an adjacent base station is damaged, UE1 and UE2 covered by a network both have an interest in becoming a relay node to provide relay services for UE3 and UE4. For example, UE1 and UE2 both are interested in becoming a UE-to-network relay.

At this moment, UE1 and UE2 may send D2D relay-related information to a network control node (hereunder description is made by taking a base station as the network control node), which includes a relay interest indication and a relay type expected to become (which may be UE-to-network relay and/or UE-to-UE relay), and may further includes a remaining power level of UE (if UE is a plug-in UE, the remaining power level may be indicated as infinite) and a current geographical location of UE. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, after the base station receives the D2D relay-related information sent by UE1 and UE2, if it is found that UE1 and UE2 are close according to geographical locations and there are no other usable relay nodes around UE1 and UE2, the base station may randomly select one from UE1 and UE2 as a UE-to-network relay node. Supposing that UE1 is selected as a relay node, the base station sends to UE1 a device-to-device communication relay configuration, which contains UE-to-network relay configuration setup information; and alternatively, it may contains fields of a relay identification, and/or a relay type, and/or a relay time length/relay time period, a relay sending and/or receiving resource and the like. Besides, the base station may also select or release a relay node according to a predefined rule and received relay-related information of UE. For example, UE1 is selected as a UE-to-network relay node according to that the remaining power level of UE1 is high and the geographical location is located at an edge of a cell. At the same time, if the base station receives a report of UE5 which has already been configured as a UE-to-network relay node and finds that the remaining power level of UE5 is low or UE5 moves to a center of the cell and UE5 has been not suitable for being used as a relay node, the base station may send to UE5 a device-to-device communication relay configuration, which contains UE-to-network relay configuration release information.

UE1 receives the device-to-device communication relay configuration sent by the base station and executes the setup of relay function according to the device-to-device communication relay configuration, and UE5 may execute the release of relay function according to the device-to-device communication relay configuration.

In addition to that UE actively send a user equipment interest to the base station, if the base station supports a device-to-device communication relay function, before the relay node selection is triggered, the request information of relay-related information may be firstly sent to UE having a relay capability or a report configuration of relay-related information is sent to UE having a relay capability, herein the report configuration of relay-related information includes the event report or periodic report, a relay-related information type which needs to be reported and the like, such that the base station can continuously receive updated state information of UE having a relay capability. If it is found that the relay-related information of UE changes, e.g., the change of the relay load state, the information of the monitored user equipment seeking relay, and the mobility state/remaining power level reported by user equipment which has already been configured as a device-to-device communication relay node exceeds a system preconfigured threshold, the base station may perform the release or reconfiguration of relay node.

In addition to the above-mentioned relay interest, the relay type expected to become, the remaining power level of UE and the current geographical location of UE, the D2D relay-related information sent by UE to the base station may further contain one or more information such as a device-to-device communication group to which UE belongs, a relay usable time period of UE, a mobility state indication of UE, a relay transmitting-receiving capability of UE, a processing capability of UE, a relay charging demand of UE, and a cellular and device-to-device communication service traffic of UE. For UE which has already been a relay node, when it is triggered periodically or by an event to report D2D relay state information to the base station, the relay load state of UE may also be reported. Herein, the relay usable time period of UE refers to a time period at which UE is usable for device-to-device communication relay; the mobility state indication of UE includes rapid, medium, slow and other different moving speed indications; the relay transmitting-receiving capability of UE refers to whether UE has dedicated transceiver hardware for relay transmitting-receiving; the processing capability of UE refers to a hardware configuration capability or capability level of user equipment, a difference reflecting the number of CPU and/or a main frequency and/or an internal memory of user equipment or data packet processing efficiency; the relay charging demand of UE refers to price compensation per data unit or time unit expected by user equipment for relay data forwarding; the current cellular service traffic of UE includes a current uplink and/or downlink cellular traffic of UE; the current device-to-device communication service traffic of UE includes a current device-to-device communication discovery and/or communication data traffic of UE; and the relay load state of UE may be a data traffic forwarded by UE as a relay and may also be a load indication relay-forwarded by UE, such as high, medium and low. The base station may comprehensively consider the above-mentioned information and select or release a relay node. For example, it is predetermined to select the following user equipment with the following relay-related information as a relay node: user equipment with a high remaining power level, and/or a low mobility state, and/or a good cellular link quality, and/or a geographical location at an edge of a non-covered area, and/or a geographic location at an edge of a cell, and/or a strong processing capability, and/or a low charging requirement and/or a low cellular and device-to-device communication service traffic; and it is predetermined to release the following relay node with the following features: user equipment with a low remaining power level, and/or a high mobility state, and/or a geographical location at a center of a cell, and/or a weak processing capability, and/or a high charging requirement and/or a high cellular and device-to-device communication service traffic.

Mary, John and Peter respectively hold UE1, UE2 and UE3 having D2D communication and relay functions. UE1 and UE2 each other are in a D2D communication range, UE2 and UE3 each other are in a D2D communication range and UE1 and UE3 each other are not in a D2D communication range. UE1, UE2 and UE3 may obtain D2D relay reception resource pool information through preconfiguration, and may also receive D2D relay resource pool information sent by a base station through broadcasting or dedicated signaling. Supposing that UE1 expects to send a data packet by means of relay to UE3 which is not in a D2D communication range, UE1 may use resources of a D2D relay resource pool to send a broadcast message for seeking D2D relay. Supposing that UE2 has an intention/interest/indication to become a relay node, UE2 may monitor the D2D relay resource pool and check whether there is a UE which is seeking a D2D relay.

Supposing that UE2 monitors D2D relay seeking information sent by UE1, UE2 may send D2D relay-related information to the base station. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, information of D2D relay finding UE1 monitored by UE2 includes one or more kinds of information of the number of monitored UE seeking the D2D relay, an identification of UE seeking D2D relay, a D2D relay type sought by UE, a communication target identification (identification of UE3) of UE1 seeking the D2D relay, whether UE2 and the communication target node UE3 of UE1 are capable of discovering each other, a measurement result of measurement performed by UE2 to UE1 seeking D2D relay (signal intensity measurement performed by UE2 to relay finding user equipment or measurement performed to a corresponding reference signal similar to RSRP/RSRQ), traffic and service quality demands of UE1 seeking D2D relay, a coverage state of UE1 seeking D2D relay, a serving cell identification of UE1 seeking D2D relay and the like. The above-mentioned information partially is obtained by UE2 by receiving D2D relay finding broadcast message sent by UE1, and partially is obtained through measurement performed by UE2.

After the base station receives the D2D relay-related information sent by UE2, if UE2 is capable of discovering the target communication node UE3 of UE1 seeking relay and at this moment there is only one candidate relay node UE2, the base station selects UE2 as a UE-to-UE relay node for D2D communication between UE1 and UE3. If the base station receives reports of a plurality of UE having a D2D relay capability and the plurality of UE all are capable of simultaneously discovering UE1 and UE3, the base station may randomly select one from these candidate user equipment as a UE-to-UE relay node. Supposing that UE2 is selected as a relay node, the base station sends to UE2 a device-to-device communication relay configuration, which contains UE-to-UE relay configuration setup information, and alternatively may contain fields of a relay identification, a relay type, a relay time length/relay time period, a relay resource configuration and the like. Besides, the base station may also select or release a relay node according to a predefined rule and received relay-related information of UE.

UE2 receives the device-to-device communication relay configuration sent by the base station and executes the setup of relay function according to the device-to-device communication relay configuration. Thereafter, relay forwarding of D2D data between UE1 and UE3 may be performed.

Officer A, B, C and D respectively use public security user equipment UE1, UE2, UE3 and UE4 having a D2D function. Officer A, B, C and D all subscribe to public security services. At a rescue place, UE1 and UE2 are in a state of being covered by a network and UE3 and UE4 are not covered by a network. In consideration of that an adjacent base station is damaged, UE1 and UE2 covered by a network both have an interest in becoming a relay node to provide relay services for UE not covered by a network. For example, UE1 and UE2 both are interested in becoming a UE-to-network relay.

UE1 and UE2 may send a measurement report of measurement performed to a serving cell and an adjacent cell to a base station, herein the measurement report includes measurement values of measurement performed to RSRP and RSRQ of the serving cell and the adjacent cell. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, after the base station receives the measurement report sent by UE1, a relative location of UE is judged according to the measurement result sent by UE1. If the measurement result performed by UE1 to RSRP of the serving cell is greater than a given threshold, the base station considers that UE1 has a basic condition of becoming a relay and the base station may select UE1 as a UE-to-network relay node and send to UE1 a device-to-device communication relay configuration, which contains UE-to-network relay configuration setup information; and alternatively it may contain fields of a relay identification, a relay type, a relay time length/relay time period, a relay resource configuration and the like. If the measurement result of measurement performed by UE1 to RSRP of the serving cell is less than the given threshold, the base station considers that UE1 is located at an edge of a cell; and if the measurement results of measurement performed by UE1 to RSRP of all adjacent cells are less than the given threshold or UE1 does not detect adjacent cells, the base station may further consider that UE1 is located at an edge of an area covered by a network, and the base station may preferentially select UE1 as a UE-to-network relay node and send to UE1 a device-to-device communication relay configuration, which contains UE-to-network relay configuration setup information; and alternatively, it may contain fields of a relay identification, a relay type, a relay time length/relay time period and the like.

Supposing that UE2 originally has already been selected as a UE-to-network relay node by the base station and the measurement result of measurement performed by UE2 to RSRP of the serving cell in the measurement report reported by UE2 is higher than the given threshold with the movement of UE2, the base station considers that UE2 is located at a center of a cell and has already been not suitable for being used as a UE-to-network relay node, and thus the base station sends to UE2 a device-to-device communication relay configuration, which contains UE-to-network relay configuration release information.

UE1 receives the device-to-device communication relay configuration sent by the base station, executes the setup of relay function according to the device-to-device communication relay configuration and starts sending D2D relay advertisement information through broadcasting, herein the D2D relay advertisement information may include one or more kinds of information of a relay identification, a relay type, a relay serving cell identification, a relay usable time period, an identification of a group to which the relay belongs, a relay mobility state indication, a relay charging demand, relay PLMN information, a relay forbidden state indication and the like.

Officer A, B, C and D respectively use public security user equipment UE1, UE2, UE3 and UE4 having a D2D function. Officer A, B, C and D all subscribe public security services. At a rescue place, UE1 and UE2 are in a state of being covered by a network and UE3 and UE4 are not covered by a network. In consideration of that an adjacent base station is damaged, UE1 and UE2 covered by a network both have an interest in becoming a relay node to provide relay services for UE not covered by a network. For example, UE1 and UE2 both are interested in becoming a UE-to-network relay.

UE1 and UE2 may obtain D2D relay resource pool information and relay selection threshold information through preconfiguration, and may also receive D2D relay resource pool information and relay selection threshold information sent by a base station through broadcasting. A relay threshold includes a serving cell link quality measurement minimum threshold, and/or a remaining power level threshold and/or a mobility state threshold. Supposing that UE1 is in an idle state, UE1 judges whether the relay threshold is satisfied according to a measurement result thereof, and starts to monitor a D2D relay reception resource pool if the relay threshold is satisfied. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, when UE1 monitors that there is no relay advertisement information sent by an adjacent D2D relay node through broadcasting, UE1 considers that there is no relay node around, and UE1 may wait for random time in a given time range, then execute a D2D relay function according to preconfiguration and starts sending a D2D relay advertisement message through broadcasting. For UE2, if at this moment UE2 monitors that there is a D2D relay advertisement message sent by an adjacent relay node through broadcasting, and UE2 further judges a relay type of an adjacent device-to-device communication relay user equipment and a measurement result of measurement performed to the received relay advertisement information. If UE2 is capable of detecting the relay advertisement information sent by UE1 through broadcasting but a signal measurement value of the corresponding relay advertisement information is lower than the given threshold, UE2 also configures UE2 as a relay node. If UE2 is not capable of detecting the relay advertisement information sent by UE1 through broadcasting or the signal measurement value of the corresponding advertisement information is higher than or equal to the given threshold although UE2 is capable of detecting the relay advertisement information sent by UE1 through broadcasting, UE2 does not configure UE2 as a relay node.

Besides, UE1 and UE2 may also configure or release their relay functions according to other predefined rules or relay-related information of user equipment. For example, it is predetermined to select the following user equipment with the following relay-related information as a relay node: user equipment with a high remaining power level, and/or a low mobility state, and/or a good cellular link quality, and/or a geographical location at an edge of a non-covered area, and/or a geographic location at an edge of a cell, and/or a strong processing capability, and/or a low charging requirement and/or a low cellular and device-to-device communication service traffic; and it is predetermined to release the relay function of the following relay node with the following features: user equipment with a low remaining power level, and/or a high mobility state, and/or a geographical location not at an edge of a non-covered area any longer, and/or a geographical location at a center of a cell, and/or a weak processing capability, and/or a high charging requirement and/or a high cellular and device-to-device communication service traffic.

After UE1 selects or configures UE1 as a relay node according to relay-related information of user equipment, if subsequently UE1 enters a connected state and receives a relay configuration performed by the base station to the user equipment, the relay configuration sent by the base station is capable of overlaying an autonomous relay configuration of the user equipment.

Officer A and B respectively use public security user equipment UE1 and UE2 having a D2D function. Officer A and B both subscribe to public security services. At a rescue place, UE1 is in a state of being covered by a network and UE2 is not covered by a network. UE1 covered by a network has an interest in becoming a relay node to provide relay services for UE not covered by a network, i.e., is interested in becoming a UE-to-network relay.

<FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, UE1 and UE2 may obtain D2D relay reception resource pool information through preconfiguration, and UE1 may also receive D2D relay reception resource pool information sent by a base station through broadcasting. UE1 which is interested in becoming a UE-to-network relay monitors a D2D relay reception resource pool. If D2D relay seeking information sent by UE2 through broadcasting is capable of being monitored, UE1 configures a relay function of UE1 according to preconfiguration and executes UE-to-network relay forwarding.

Embodiment <NUM> to embodiment <NUM> describe processes that a base station and user equipment select a relay node.

Officer A, B and C respectively use public security user equipment UE1, UE2 and UE3 having a D2D function. Officer A, B and C all subscribe to public security services. At a rescue place, UE1 is in a state of being not covered by a network and UE2 and UE3 both are in a state of being covered by a network. In consideration of that an adjacent base station is damaged, UE2 and UE3 covered by a network both have an interest in becoming a relay node to provide relay services for UE not covered by a network. For example, UE1 and UE2 both are interested in becoming a UE-to-network relay and have already been configured by a network as UE-to-network relay nodes.

UE1 monitors a relay reception resource pool according to the preconfigured relay reception resource pool and detects whether there is relay-related information sent by an adjacent node through broadcasting. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, the relay-related information may include one or more of the following information: a relay node identification, a relay node remaining power level, a device-to-device communication group to which a relay node belongs, a relay usable time period of a relay node, a relay type, a mobility state indication of a relay node, a relay transmitting-receiving capability of a relay node, a processing capability of a relay node, a relay charging demand of a relay node, a covering state of a relay node, a serving cell identification of a relay node, a minimum number of hops from a relay node to a network node, a relay load state of a relay node, an access forbidden state of a relay node, PLMN information of a relay node and the like. Herein, the relay usable time period refers to a time period at which a relay node executes a device-to-device communication relay function; the mobility state indication includes rapid, medium, slow and other different moving speed indications; the relay transmitting-receiving capability refers to whether UE has dedicated transceiver hardware for relay transmitting-receiving; the processing capability refers to a hardware configuration capability or capability level of user equipment, a difference reflecting a number of CPU and/or a main frequency and/or an internal memory of user equipment or data packet processing efficiency; the relay charging demand refers to price compensation per data unit or time unit expected by a relay node for relay data forwarding; and the relay load state may be a data traffic forwarded by UE as a relay and may also be a load indication relay-forwarded by UE, such as high, medium and low. Besides, the relay-related information further includes a result of measurement performed by UE1 to a signal of relay-related information sent by a relay node.

Supposing that UE1 monitors relay advertisement information sent by UE2 and UE3, UE1 acquires relay-related information contained therein. UE1 judges measurement results of measurement performed to UE2 and UE3 satisfy a relay selection minimum device-to-device communication link quality threshold according to a preconfigured relay selection threshold. If the threshold is not satisfied, UE1 continuously monitors whether there is relay discovery information sent by other UE around. If the threshold requirement is not satisfied, UE1 continuously selects a relay access node according to a predefined rule and the acquired relay-related information, e.g., selects a relay node with a high remaining power level, or a low mobility state, or a geographical location adjacent to the user equipment, or a strong processing capability, or a low cellular and device-to-device communication service traffic, or a low relay load, or a relay access forbidden state which is a non-forbidden state, or a PLMN/D2D group consistent with the user equipment, as an access relay node. The predefined rule may be preconfigured or sent by the base station through broadcasting or dedicated signaling, and includes a remaining power level requirement of relay node, or a geographical location requirement of relay node (which is determined according to whether a measurement value of measurement performed by user equipment to a signal of a relay node satisfies a given threshold), or a mobility state requirement of relay node, or a processing capability requirement, or a cellular and device-to-device communication service traffic requirement, or a load requirement of relay node or the like. Supposing that the preconfigured predefined rule is a geographical location requirement, it is required that UE selects a relay node with the largest measurement value of the signal of the relay node. Supposing that the signal intensity, measured by UE1, of the relay advertisement information sent by UE2 is higher than that of UE3, UE1 selects UE2 as a relay access node and starts accessing to perform D2D data forwarding.

Officer A, B, C and D respectively use public security user equipment UE1, UE2, UE3 and UE4 having a D2D function. Officer A, B, C and D all subscribe to public security services. At a rescue place, UE1, UE2, UE3 and UE4 all are in a state of being not covered by a network. UE1, UE2 and UE3 each other are in a D2D communication range, UE2, UE3 and UE4 each other are in a D2D communication range, and UE1 and UE4 each other are not in a D2D communication range. UE1, UE2, UE3 and UE4 not covered by a network all have an interest in becoming a UE-to-UE relay node to provide relay services for UE not covered by a network.

UE1 expects to perform relay-based D2D communication with UE4. Firstly UE1 monitors a relay reception resource pool according to preconfigured relay reception resource pool information and detects whether there is relay-related information sent by an adjacent node through broadcasting. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, if UE1 monitors no relay advertisement information sent by an adjacent node through broadcasting, UE1 sends a message for seeking D2D relay, i.e., a relay discovery message, through broadcasting on the relay reception resource pool. The broadcast message for seeking D2D relay may include an identification of UE1, a D2D relay type sought by UE1 (UE-to-UE relay), a communication target identification of UE1 (identification of UE4), traffic and service quality demands of UE1 and the like.

UE2 and UE3 which have an interest in becoming a UE-to-UE relay node monitor the relay reception resource pool according to the preconfigured relay reception resource pool information and detect whether there is relay-related information sent by an adjacent node through broadcasting. Supposing that UE2 and UE3 both receive the message for seeking D2D relay sent by UE1, and UE2 and UE3 both are capable of discovering UE4 and performing D2D communication with UE4, UE2 and UE3 send relay advertisement information containing relay-related information, which includes one or more information of a relay node identification, a relay node remaining power level, a device-to-device communication group to which a relay node belongs, a relay node usable time period of a relay node, a relay type, a mobility state indication of a relay node, a relay transmitting-receiving capability of a relay node, a processing capability of a relay node, a relay charging demand of a relay node, a coverage state of a relay node, a serving cell identification of a relay node, a minimum number of hops from a relay node to a network node, a relay load state of a relay node, an access forbidden state of a relay node, PLMN information of a relay node and the like. Herein, the relay usable time period refers to a time period at which a relay node executes a device-to-device communication relay function; the mobility state indication includes rapid, medium, slow like different moving speed indications; the relay transmitting-receiving capability refers to whether UE has dedicated transceiver hardware for relay transmitting-receiving; the processing capability refers to a hardware configuration capability or capability level of user equipment, a difference reflecting a number of CPU and/or a main frequency and/or an internal memory of user equipment or data packet processing efficiency; the relay charging demand refers to price compensation per data unit or time unit expected by a relay node for relay data forwarding; and the relay load state may be a data traffic forwarded by UE as a relay and may also be a load indication relay-forwarded by UE, such as high, medium and low. Besides, the relay-related information further includes a result of measurement performed by UE1 to a signal of relay-related information sent by a relay node.

Supposing that UE1 monitors relay advertisement information sent by UE2 and UE3, UE1 acquires relay-related information contained therein. Then, UE1 selects a relay access node according to a predefined rule and the acquired relay-related information, e.g., it selects a relay node with a high remaining power level, or a low mobility state, or a geographical location adjacent to the user equipment, or a strong processing capability, or a low cellular and device-to-device communication service traffic, or a low relay load, or a relay access forbidden state which is a non-forbidden state, or a PLMN/D2D group consistent with the user equipment, as an access relay node. The predefined rule may be preconfigured or sent by the base station through broadcasting or dedicated signaling, and includes a remaining power level requirement of relay node, a geographical location requirement of relay node (which is determined according to whether a measurement value of measurement performed by user equipment to a signal of a relay node satisfies a given threshold), a mobility state requirement of relay node, a processing capability requirement, a cellular and device-to-device communication service traffic requirement and a load requirement of relay node. Supposing that the preconfigured predefined rule is a mobility state requirement of relay node, it is required that UE selects a relay node with the slowest mobility state. Supposing that the mobility state of UE2 is slower than that of UE3, UE1 selects UE2 as a relay access node and starts accessing to perform D2D data forwarding.

Mary, John, Peter and Rose respectively hold UE1, UE2, UE3 and UE4 having D2D communication and relay functions. UE1, UE2 and UE3 each other are in a D2D communication range, UE2, UE3 and UE4 each other are in a D2D communication range, and UE1 and UE4 each other are not in a D2D communication range.

UE1 expects to perform a relay-based D2D communication with UE4. Firstly UE1 monitors preconfigured relay reception resource pool information and detects whether there is relay-related information sent by an adjacent node through broadcasting. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, it is supposed that at this moment UE2 and UE3 both are configured as a D2D relay node, support UE-to-UE relay and send D2D relay advertisement information. UE1 collects the D2D relay advertisement information sent by adjacent nodes UE2 and UE3 through broadcasting and performs measurement to D2D relay advertisement signals.

Thereafter, UE1 sends a relay request to eNB, which may include relay configuration request information; and alternatively, it may include a requested relay type, a D2D communication group to which UE1 belongs, a geographical location of UE1, and relay node related information sent by a monitored relay node through broadcasting.

After the relay request information sent by UE1, eNB judges an adjacent relay node according to the geographical location of UE1 and acquires relay-related information corresponding to the adjacent relay node. The relay-related information corresponding to the adjacent relay node may be reported by UE1 to eNB through a relay request; or UE1 only sends the monitored relay node identification, and eNB determines the related information of the corresponding relay node according to previous configuration thereof or requests the relay node to send the relay-related information to eNB through the dedicated signaling.

The eNB judges the relay type requested by the user equipment, finds out a set of relay nodes corresponding to the relay type and adjacent to the user equipment, and it may randomly select an access relay node for UE1, or eNB configures or reconfigures an access relay node for UE1 according to a predefined rule and relay-related information. For example, a relay node with a high remaining power level, and/or a low mobility state, and/or a geographical location adjacent to the user equipment, and/or a strong processing capability, and/or a low charging requirement, and/or a low cellular and device-to-device communication service traffic, and/or a low relay load, and/or a relay access forbidden state which is a non-forbidden state, and/or a PLMN/D2D group consistent with the user equipment, may be selected. Supporting that eNB finally selects UE2 as a UE-to-UE relay access node of UE1, eNB sends an access relay node configuration to UE1, herein the device-to-device communication relay access configuration may include configuration of setup, release or modification of the access relay node.

UE1 receives the access relay node configuration information sent by eNB, then executes the setup of the access relay node configuration according to the access relay node configuration, and starts accessing to the access relay node UE2 to perform D2D data forwarding communication.

UE1 expects to perform the relay-based D2D communication with UE4. Firstly UE1 monitors a relay reception resource pool according to preconfigured relay reception resource pool information and detects whether there is relay-related information sent by an adjacent node through broadcasting. <FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, supposing that UE1 does not detect any D2D relay advertisement information, UE1 sends to eNB a relay request, which may include relay configuration request information which may contains a requested relay type, a D2D communication group to which UE1 belongs, a geographical location of UE1 and the like.

After the relay request information of UE1 is received, eNB judges adj acent user equipment having a D2D relay capability according to the geographical location of UE1, and sends a relay information request to the UE having the relay capability or sends a report configuration of relay-related information to the UE having the relay capability, herein the report configuration of the relay-related information includes event report or periodic report, a type of relay-related information which needs to be reported and the like, such that eNB may continuously receive updated state information of the UE having the relay capability.

If the base station receives reports of a plurality of UEs having the D2D relay capability, the base station may randomly select one from these candidate nodes as a UE-to-UE relay node. Supposing that UE2 is selected as a relay node, the base station sends to UE2 a device-to-device communication relay configuration, which contains UE-to-UE relay configuration setup information; and it specifically may contain fields of a relay identification, a relay type, a relay time length/relay time period and the like. UE2 receives the device-to-device communication relay configuration and executes relay function setup according to the device-to-device communication relay configuration.

Then, eNB sends an access relay node configuration to UE1, and the device-to-device relay access configuration may include an setup configuration of the access relay node, which contains identification information of the relay access node UE2. UE1 receives the access relay node configuration information sent by eNB, then it executes the setup of the access relay node configuration according to the access relay node configuration, and starts accessing to the relay node UE2 to perform D2D data forwarding communication.

<FIG> illustrates a schematic diagram of information interaction for realizing device-to-device communication relay selection according to embodiment <NUM> of the present invention. As illustrated in <FIG>, UE1 has already selected relay UE2 and established a connection with UE2 to perform data forwarding. Subsequently UE1 detects that a link measurement result (S2) of measurement performed to relay UE2 is lower than a relay reselection device-to-device communication link threshold, the user equipment starts to monitor a preconfigured relay reception resource pool. Supposing that UE1 monitors no relay discovery information (i.e., relay seeking information) sent by other adjacent relay nodes through broadcasting, UE1 sends a message for seeking D2D relay through broadcasting on a relay sending resource pool. Supposing that UE1 monitors relay response information sent by relay UE3, UE1 acquires relay-related information contained therein and performs measurement to signal intensity thereof, herein a measurement result is S3. Thereafter, UE1 performs ranking to (S2+relay reselection hysteresis value) and S3. If S3 is higher, UE1 selects relay UE3 as an access relay node and starts trying to establish a connection to perform D2D data forwarding.

One skilled in the art can understand that all or partial steps in the above-mentioned methods may be completed by relevant hardware (such as a processor) instructed by a program, and the program may be stored in a computer readable storage medium such as a read-only memory, a magnetic disc or a compact disc. Optionally, all or partial steps in the above-mentioned embodiments may also be implemented by using one or more integrated circuits. Correspondingly, each module/unit in the above-mentioned embodiments may be implemented by means of hardware, e.g., a corresponding function thereof may be implemented through an integrated circuit, and it may also be implemented by means of a software function module, e.g., a corresponding function thereof may be implemented through a processor which executes a program/instruction stored in a memory. The present invention is not limited to combinations of hardware and software in any specific form.

Claim 1:
A method for realizing device-to-device communication relay selection, comprising:
receiving, by a user equipment, relay-related information sent by an adjacent relay node; and
selecting, by the user equipment, an access relay node;
the method further comprises: before the user equipment receives the relay-related information, receiving, by the user equipment, a relay reception resource pool and/or a relay selection threshold preconfigured or sent by a network control node through broadcasting or dedicated signaling;
wherein the relay selection threshold comprises: a relay selection minimum device-to-device communication link quality threshold, and/or a relay reselection device-to-device communication link threshold and/or a relay reselection hysteresis value;
characterized in that, the method further comprises: when the user equipment has not selected the access relay node, or the user equipment has already selected the access relay node but a measurement result of measurement performed by the user equipment to the relay-related information sent by the selected access relay node is less than the relay reselection device-to-device communication link threshold, the user equipment monitoring the relay reception resource pool and receiving the relay-related information sent by the adjacent relay node;
wherein the relay-related information comprises at least one of:
a relay type supported by the adjacent relay node;
a minimum number of hops from the adjacent relay node to a network node;
an access forbidden state of the adjacent relay node; or
Public Land Mobile Network PLMN information of the adjacent relay node.