A device to device (D2D) discovery process is a process of determining whether a D2D-enabled user equipment (UE) is in a proximity of other D2D-enabled UE. A discovering D2D-enabled UE determines whether other D2D-enabled UE is of interest to the discovering D2D-enabled UE based on the D2D discovery process. The other D2D-enabled UE is of interest to the discovering D2D-enabled UE if proximity of the other D2D-enabled UE needs to be known by one or more authorized applications on the discovering D2D-enabled UE. For example, a social networking application may be enabled to use a D2D discovery feature. The D2D discovery process enables a D2D-enabled UE of a given user of a social networking application to discover D2D-enabled UEs of friends of the given user of the social networking application, or to be discoverable by the D2D-enabled UEs of the friends of the given user of the social networking application. In another example, the D2D discovery process may enable the D2D-enabled UE of a given user of a search application to discover stores/restaurants, and the like of interest of the D2D-enabled UE of the given user of the search application in proximity of the D2D-enabled UE of the given user of the search application.
Discovery information transmitted during a D2D direct discovery process may be used below.
Firstly, the discovery information may be used as D2D application user identification. That is, in the D2D direct discovery process, a D2D-enabled application may detect a D2D-enabled UE for other user which is in proximity of the D2D-enabled application based on the discovery information.
Secondly, the discovery information may be used as interest information. That is, in the D2D direct discovery process, a user of a D2D-enabled application may discover another user of its interest in its proximity.
After discovering the user to which the discovering UE is of interest, the discovering UE may establish a dedicated connection with the discovered user in order to perform a communication between the discovering user and the discovered user. In order to establish the dedicated connection, there is a need for a UE identifier (ID) of the discovered UE. Here, in the communication network, the UE is identified based on the UE ID. The UE ID is needed to locate the UE in the communication network. The UE ID is needed to identity a UE corresponding to the application user by the communication network. It is noted that the application user is discovered during the direct D2D discovery process. Meanwhile, a scheme of determining the UE ID is a scheme of transmitting the UE ID in the discovery information. A size of a discovery channel is generally very small, and a size of the UE ID is relatively large. For example, the size of the UE ID may be maximum 80 bits. So, it is not feasible to transmit the UE ID through the discovery channel due to the size of the UE ID. Also, it is not advisable to transmit the UE ID through the discovery channel due to security reasons.
A network authorized direct connection establishment process in a communication system supporting a D2D scheme of the related art will be described with reference to FIG. 1.
FIG. 1 schematically illustrates a network authorized direct connection establishment process in a communication system supporting a D2D scheme according to the related art.
Referring to FIG. 1, the communication system includes a UE #1 111, an evolved node B (eNB)#1 113, a mobility management entity (MME) 115, an eNB #2 117, and a UE #2 119.
The UE #1 111 discovers the UE #2 119, and determines to establish a connection with the UE #2 119 at operation 121. During the discovery process, the UE #1 111 receives a discovery code for an application user of the UE #2 119. The discovery code is an alias for the application user. During the discovery process, a UE ID of the UE #2 119 is not transmitted by the UE #2 119. In order to establish a direct connection with the UE #2 119, the UE #1 111 transmits a direct connection request message to an eNB for a camped cell of the UE #1 111, e.g., the eNB #1 113 at operation 123. The direct connection request message includes a discovery code for the application user which is received by the UE #1 111 during the discovery process. After receiving the direct connection request message from the UE #1 111, the eNB #1 113 transmits the direct connection request message to the MME 115 at operation 125. After receiving the direct connection request message from the eNB #1 113, the MME 115 transmits a paging message including a direct connection indication parameter to the eNB #2 117 at operation 127. After receiving the paging message from the MME 115, the eNB #2 117 transmits the paging message to the UE #2 119 at operation 129. After receiving the paging message from the eNB #2 117, the UE #2 119 transmits a direct connection request message to the eNB #2 117 in response to the paging message at operation 131. After receiving the direct connection request message from the UE #2 119, the eNB #2 117 transmits the direct connection request message to the MME 115 at operation 133. After receiving the direct connection request message from the eNB #2 117, the MME 115 establishes a radio resource control (RRC) connection with the UE #1 111 through the eNB #1 113 at operation 135. That is, an RRC connection establishment process is performed among the UE #1 111, the eNB #1 113, and the MME 115. The MME 115 establishes an RRC connection with the UE #2 119 through the eNB #2 117 at operation 137. That is, an RRC connection establishment process is performed among the MME 115, the eNB #2 117, and the UE #2 119. So, an RRC connection is established between the UE #1 111 and the eNB #1 113, and an RRC connection is established between the UE #2 119 and the eNB #2 117. After the RRC connection is established, a direct connection signaling process is performed between the UE #1 111 and the UE #2 119 at operation 139. During the direct connection signaling process, direct connection parameters may be set up between the UE #1 111 and the UE #2 119. If there are no direct connection parameters to be set up, the process of setting up the direct connection parameters is not performed.
As described in FIG. 1, in a network authorized direct connection establishment process in a communication system supporting a conventional D2D scheme, it is not specified how the MME 115 determines the UE ID of the UE #2 119 from the discovery code of the UE #2 119. As described in FIG. 1, in a network authorized direct connection establishment process in a communication system supporting a conventional D2D scheme, it is not specified how the MME 115 determines location of the UE #2 119. The UE #2 119 may be associated with the same MME, other MME, or an MME which is included in other public land mobile network (PLMN). However, in order to establish a network authorized direct connection between the two UEs, there is a need for specifying how the MME 115 determines the UE ID of the UE #2 119 from the discovery code and how the MME 115 determines location of the UE #2 119.
So, there is a need for a scheme of determining an ID and location of a UE in order to establish a network controlled direct connection in a communication system supporting a D2D scheme.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.