TTCM-Aided SDMA-Based Two-Way Relaying

A novel power- and bandwidth-efficient Turbo Trellis Coded Modulation (TTCM) assisted Space Division Multiple Access (SDMA) based two-way relaying scheme is proposed. The scheme advocated was designed for enhancing the throughput, reliability and coverage area in a cooperative communication system. A twin-antenna Relay Node (RN) is employed for assisting a pair of users, where each user is equipped with a single-antenna mobile unit. During the first transmission period, both users transmit their TTCM-encoded signals to the RN. The twin-antenna RN then detects these signals using various SDMA-based detection algorithms. Iterative SDMA and TTCM detection is invoked at the RN, which then broadcasts the re-encoded TTCM signals to both users during the second transmission period. Finally, each user retrieves the opposite user´s signals received from the RN. Our proposed scheme outperforms the non-cooperative TTCM scheme by approximately 5.3 dBs at a BER of 10^-6, when communicating over uncorrelated Rayleigh fading channels.