Research On Power Allocation And Relay Selection Based On Relay Technique Algorithms In D2D System

D2D(Device to Device)communication system is a short distance communication mode that allows the signal to be transmitted directly between the transmitter and the receiver.D2 D communication can not only improve the spectrum utilization of the whole system by flexible wireless resource reuse,but also reduce the load of the base station and obtain better communication performance.Furthermore,adding relay nodes in D2 D system can not only avoid communication outage between users in deep fading channels,but also expand the communication coverage of D2 D.Because of wireless resource sharing between D2 D users and traditional cellular users,co-channel interference in D2 D link and cellular link should be considered when selecting relay nodes and allocating resource.Thus,efficient algorithms of relay selection,power allocation and resource allocation are important in D2 D communication system.This paper focuses on the power allocation and relay selection algorithms in the one-way relay D2 D transmission system and the two-way relay D2 D system.For the one-way relay D2 D transmission scenario,a power allocation and relay selection algorithm in the one-way relay D2 D systems is proposed.This algorithm ensures the communication quality of the original cellular users and the communication quality of the D2 D users.Aiming at minimizing the total transmitted power of the hybrid network,the power between the cellular link and the D2 D link is allocated and the best relay node is selected.Simulation results show that compared with the random selection algorithm,the proposed algorithm can significantly reduce the total power consumed by the hybrid network.For the two-way relay D2 D transmission scenario,D2 D communication,network coding and relay technology are combined,and a two-way relay D2 D communication system model with multiple alternative relays is established using non-orthogonal wireless resource reuse mode under the centralized control of base station.An optimal power allocation and best relay node selection algorithm based on network coding is proposed.Fixing the total power of the D2 D link to transmit,this algorithm optimizes the transmission power of each node,and selects the relay node which can maximize the channel capacity of D2 D link as the best relay node.Simulation results show that compared with other protocols,the proposed protocol can significantly improve the channel capacity of D2 D link.