Multiple Sets Of Multi-user Two-way Relay Technology In Wireless Communication Research

Two-way relay network has been drawing increasing attention of both the academic and industry recently for its potential in expanding coverage and improving spectral efficiency. Multi-group multiuser two-way relay network (MGMUTWRN), where users of each group performs bidirectional commu-nications via the assistance of the relay node, is a quite practical communica-tion scenario. Two kinds of interferences, namely intra-group interference and inter-group interference, which severely degrade the system performance, exist in the addressed scenario. How to deal with these two kinds of interference to alleviate the performance deterioration is a challenging issue. This thesis fo-cuses on interference treatment in MGMUTWRN composed of single-antenna users and multi-antenna relay node. The main contributions of the thesis are summarized as follows.First we investigate how to combat interferences in a MGMUTWRN con-sisting of two single-antenna users and a relay node which is equipped with two antennas. For the reason that the antenna number of the relay node is only half the total number of single-antenna users which means the antenna num-ber of the relay node is less than the total number of users, beamforming at cancelling intra-group interference is no longer applicable. Thus, we propose a scheme integrating physical layer network coding (PNC) and superposition coding (SC) to combat interferences. PNC is employed to cancel intra-group interference while SC is deployed to cope with inter-group interference. To make full utilization of the two antennas of the relay node, Space-Time Coding is adopted to achieve spatial diversity. In order to evaluate the performance of the proposed scheme, we choose average sum rate and outage probability as the metrics and explicit analysis is presented as well. Simulation results match well with theoretical analysis and show that the performance of the proposed scheme outperforms that of other existing ones.Then we analyze the applicability of the scheme to the general MG-MUTWRN with any group number. When the number of user group becomes larger, inter-group interference increases as well. It’s still of great importance to develop interference-combatting schemes in order to improve system perfor-mance. To find out whether the proposed scheme is applicable to the general MGMUTWRN, average sum rate and outage probability are still chosen as the performance metrics. Theoretical analysis and simulation results shows that the proposed scheme still works in the general MGMUTWRN and can obtain better performance than the existing approach.Finally, the thesis is summarized and possible research directions are dis-cussed.