Method to improve two bi-directional halfduplex relaying scheme under use of singleuser decoder

A two bi-directional-way relaying method that enables simultaneous communication without inter-pair interference within two time slots is proposed. A common sensor node B exchanges information with two sensor nodes S₁ and S₂ via two relaying scenarios. In the first scenario, the relaying system contains two relays, R₁ and R₂, in two overlapping clusters. In the second scenario, the relaying system has only one relay, R, in the same cluster. Under the amplify-and-forward protocol, the authors propose the use of a pulse amplitude modulation signal, instead of a general complex signal, for presenting informational messages of all sources. The authors then propose a phase-shift transmission scheme. As a result, two-bi-directional relaying transmission is available within two time slots, but without any interference. Simulation results show that in terms of achievable rate, the proposed scheme outperforms the conventional method which uses a general complex signal and four time slots.