Communication Schemes for Gaussian Two-way Relay Networks

Student thesis: Master Thesis and HD Thesis

  • Kasper Fløe Trillingsgaard
Relaying is a transmission technique that promises coverage extension and an increased spectral efficiency. The advent of two-way relaying based on network coding opened a large design space in wireless networks. Two related topics are addressed in this thesis: interactive two-way relaying and extension of the wireless network coding principle to larger networks. The first part attempts to increase the achievable rates of the amplify-and-forward scheme for the traditional two-way relay channel using interaction. Two extended amplify-and-forward schemes are put forth, and the achievable rates are computed. Simulation results, however, show that
no improvements are achieved using the proposed schemes. This once more confirms why there are so few interactive communication strategies in information theory that lead to nontrivial improvements. The second part addresses coordinated relaying, which is a generalization of two-way relaying. In particular, the study focuses on the shared relay, in which two base stations wish to attain two-way communication to two terminals through one relay. The relay schemes, precode-and-forward and decode-and-forward, are extended to this relay network using the concepts of zero-forcing and alignment. The simulation results show that the decode-and-forward scheme performs well at low SNR while precode-and-forward is better at high SNR. Finally, it is illustrated how these concepts can scale to larger networks.
Publication date6 Jun 2013
Number of pages71
ID: 77296102