Research On Device To Device Relay Selection Strategy In LTE-Advanced Network

In recent years, with the rapid progress of the Internet of Things and the Social Network Services, the network topology is more and more flat as well as the demand of device to device communication becomes even more frequently. In that condition, the D2 D technology is popularly spreading. The mobile internet also gets a great development now days from the third generation to the fourth generation which has higher transmission rate. However, the traditional cellular network is not so satisfied for people’s communication requirement since the swift growth of mobile users and the life dependence heavily to the mobile network. Hence, even more researchers devote to the research on D2 D technique in cellular network. As a key technology in D2 D communication, D2 D relay technology can expand expand the communication radius of D2 D communication and improve the D2 D communication link quality and stability.The most critical step for D2 D relay communication is the selection of D2 D relay nodes, which can effectively improve the performance of relay communication and reduce the mutual interference between cellular network and D2 D network by selecting the optimal relay node. However previous studies less consideration D2 D frequency resource allocation, only considers the relay selection algorithm when the position and power of the interference are fixed, while ignoring the influence of the location and the power of interference on the relay communication. Previous studies typically consider the relay selection problem for only one pair of D2 D users, while ignoring the condition of multiple pairs of D2 D users and multiple relay nodes participating the D2 D relay selection strategy at the same time, which make no sense when there have large amount of D2 D users who need relay service.To solve the above two problems, this thesis designs a D2 D relay selection scheme based on the location information, which will divide the D2 D relay selection into two steps: D2 D frequency resource allocation and D2 D relay node selection. Firstly, this thesis designs a resource allocation scheme based on the location information in the condition of multiplexing the uplink frequency resource of the cellular users. Under the premise of satisfying the SINR of the eNB, the scheme will choose the cellular user which can maximize SINR of the D2 D users as the resource reuse object. At the same time, the transmit power of the cellular user and D2 D users will be adopted. Then this thesis designs a two-way D2 D relay selection strategy based on the position and CSI information. The relay users will first screen the D2 D users by their location information, thus the scheme can divide the relay nodes and D2 D users into groups so that the relay section processing can be accomplished at the same time. Then D2 D users will choose the best relay node based on CSI information through the channel measuring. The proposed scheme can effectively solve the problem of relay selection when there exists multiple D2 D users and multiple relay users, which can reduce the conflict of channel measurement, and also reduce the number of interactions in the processing of relay selection.