Technology Research On Full-duplex Relay Selection

The full duplex technology is able to achieve a goal that signals can transmit and receive at the same time-frequency. Compared to the traditional half duplex system, the full duplex technology can obtain a doubling of the spectral efficiency theoretically. However, it will introduce self-interference at the same time, which suppresses the system performance that full duplex has brought. It means that the degree of self-interference will directly affect the performance of the whole system.In recent years, the ability of self-interference cancellation is greatly improved; so that the application of full duplex technoloty in relay system is becoming possible.Relay technology has been widely used in traditional half duplex relay system to enhance the communication link capacity of the system. After the introduction of full duplex technology,whether the traditional relay selection strategies are suitable or not needs further analysis due to the presence of the self-interference. Therefore, it has important theoretical and application value to carry out the research of relay selection technology in full duplex relay systems.In this paper,we mainly study the relay selection and power allocation algorithms in the full duplex relay system. The contributions and innovations are as follows:(1) For decode-and-forward full duplex relay system model,including full duplex relay nodes and a pair of half duplex source and destination node, assuming that all or part of the channel state information has already been known. This thesis proposes an analysis method of outage probability for different relay selection stratigies in relay-oriented system. Then, the outage probability of the optimal relay selection scheme, the Max-Min relay selection scheme, the partial relay selection scheme and the relay selection scheme are derived respectively.In addition, this thesis analyzed the impact of the residual self-interference, the number of relay and the wireless channel environment on the outage probability. The correctness of the theoritical analysis is verified by Monte-Carlo simulations, which provides a reference for the application of full duplex technology in the relay system.(2) For a two-hop amplify-and-forward relay cooperative communication system that is made up of a full duplex node and a pair of half duplex source and destination node. A power allocation algorithm with joint independent power constraint and total power constraint is proposed in this thesis to perform power allocation for the source and relay nodes, which takes maximizing the system capacity as the objective.The proposed algotithm solves the optimal power allocation problem by analyzing the boundary conditions under the joint power constraint, and compares the capacity performance of the joint algotithm and the traditional algotithm. Simulation results show that the joint algorithm can balance the transmission power and link capacity better.