Study on D2D Relay Transmission Algorithm in Cellular Networks

The introduction of Device-to-Device (D2D) communication technology can effectively improve the utilization ratio of spectrum resources of cellular networks. However, when D2D communication multiplexes cellular spectrum resources, the cellular signal and D2D signal would not be obtained by cellular user or D2D receiver due to the interference between cellular signal and D2D signal. To solve this problem, a D2D relay transmission algorithm based on complex field network coding (CFNC) is proposed in this paper. Specifically, as CFNC is adopted in the relay node to encode the received cellular signal and D2D signal, cellular signal and D2D signal are recovered respectively by the D2D receiver and the cellular user with maximum likelihood detection. Performance analyses and simulation results show that, compared with the traditional D2D transmission algorithm, the proposed algorithm can significantly improve the system achievable rate, and moreover reduce the outage probability. Introduction As a key technique of 4G communication, Device-to-Device (D2D) communication improves the utilization ratio of cellular spectrum resources by multiplexing the spectrum resources of cellular networks. The transmission power of the terminal user can be reduced due to the short communication distance. Consequently, D2D communication has aroused researchers’ widespread concerns. In [1], D2D communication underlaying a 3GPP LTE-Advanced cellular network is studied, showing that D2D communication can increase the total throughput observed in the cell area. From the perspective of practical application, Cui et al. point out that the application of D2D technology in LTE-A system can increase the throughput of cellular system, but it will causes signal interference at the same time [2]. When D2D communication multiplexes the spectrum resources of cellular networks, cellular user and D2D receiver cannot correctly recover the corresponding cellular signal and D2D signal because of the mutual interference between cellular signal and D2D signal. Towards the problem above, there are several methods of resource management and power control proposed to solve the signal interference [3-5]. A resource allocation algorithm based on interference-aware in D2D communication is proposed in [6], in which the base station adjusts the transmission power of D2D communication to control the interference, but resource utilization ratio is low. Zulhasnine et al. proposed an efficient resource allocation scheme for D2D communication to maximize the throughput of D2D communication link, but this scheme could not guarantee the reliable transmission of D2D links [7]. Resource reusing and interference coordination scheme is studied in [8], nevertheless in which the authors only consider individual interference and ignore the whole system. In the aspect of power control, Gu et al. proposed a dynamic power control mechanism, which can dynamically adjust the D2D transmit power, but cannot distinguish the uplink and downlink mode of multiplexing resource [9]. According to the minimum signal to noise ratio (SNR) of the cellular users and the D2D users as well as the maximum transmission power of the user