The Research Of Full-duplex Relays And Bi-directional Transmission Technology

With the continuous development of mobile communication technology and people’sincreasingly growing demand for communications networks in recent years, single-channelFull-duplex (FD) relaying technology is ushering in a new development opportunity. FD relayscould enhance system capacity, so it has high theoretical and practical significance to study FDrelaying technology. This thesis studies the sum rate performance in FD relaying systems under thecircumstance of single-input single-output (SISO) and multiple-input multiple-output (MIMO) linkand the transmission strategy of FD relays. The main work includes:(1) It summarizes the theoretical research status, some of the basic principles and some keytechnologies of FD relaying systems, and then it introduces precoding technology of MIMO relays.(2) Aiming at the self-interference problem caused by FD relays, the feasibility of FD relayshas been studied, i.e. there exists a self-interference threshold under which the performance of FDrelays is superior than that of half-duplex (HD) relays. Meanwhile a two-hop low-altitude relayingcommunication system suitable for emergency communication has been studied in place of directtransmission link. Finally, the interference problem between multiple linear low-altitude relays hasbeen studied.(3) Two optimization processing schemes of FD relays’ sum rate performance under thecircumstance of SISO link has been studied. Scheme1jointly designs the FD relays transmissionmatrix and the precoding matrix of the source, which using amplify-and-forward (AF) protocol,obtaining higher sum rate than that of HD relays. In scheme2the FD relay using the receiving filterto receive and transmit, optimizing the end-to-end signal to interference and noise ratio (SINR) ofAF and decode-and-forward (DF) protocols, to enhance system sum rate performance.(4) One transmission strategy design of multi-user MIMO FD relaying systems has beenstudied under the circumstance of MIMO link. To enhance the uplink sum rate, a downlink userselection scheme has been studied, whose core idea is to turn off data streams of users whose normof downlink channel matrix is relatively smaller, and thereby improves the uplink sum rate.