Full Duplex Relay Key Technology Research

Cooperative communication employing relays has attracted a lot of attention for its potential of improving the performance of the wireless communication. Relay is essential to provide reliable transmission, high throughput and wide-ranging for wireless network. There are two types of relay schemes, half-duplex (HD) relay and full-duplex (FD) relay. Most systems apply HD relay due to the difficulty in implementing FD relay in practice. The HD relay uses two (or more) orthogonal time or frequency slots to transmit and receive signal, which leads to50%or more loss in spectral efficiency. The FD relay transmits and receives simultaneously at the same frequency band, resulting no spectral efficiecy loss. However, the huge power differences of relay’s transmitted and received signals cause self-interference at the relay’s receiver front-end, resulting in reduced channel capacity. The interference cancellation thus becomes crucial in the FD relay system which must be carefully addressed. In this paper, we study three FD relay systems which suffer from the interference, the interference cancellation algorithm is proposed to fully remove the interference. At the same time, the transmission beamforming matrix at the source and the relay are also jiontly optimized to maximize the capacity. Numerical results show the performance of the FD relay system.The paper is organized as follows. Chapter1introduces the background of the relay system, the main controbutions of this paper, and the structure arrangements. Chapter2study the performance analysis of a FD relay system that suffers from self-interference for both decode-and-forward (DF) and amplify-and-forward (AF), where all nodes are euqipped with multiple antennas. Chapter3introdudes the two-path successive SISO relay system, and a interference cancellation approach is introduced to fully remove the inter-relay interference at the destionation. Chapter4study the inter-interference cancellation in the two-path relay system with nodes having multiple antennas, a new interference cancellation algorithm is porposed to fully remove the IRI at the relays, where the IRI cancellation is divided between two relays, leading to a flexible system. the transmission beamforming matrix at the source and the amplifying matrices at the relays are jointly designed to maximize the capacity under the power constraint. Chapter5summarizes the contributions of this paper and give some interesting further research.