Turbo Coded and Cooperative Network Coded Non-Coherent Soft-Decision Star-QAM Dispensing with Channel Estimation

Star Quadrature Amplitude Modulation (Star-QAM) is a non-coherent detection aided scheme ideal for low-complexity wireless transceivers. In this contribution, we first derive soft-decision aided StQAM symbol-to-bit demapping combined with iterative detection aided Turbo Coding (TC). Then we combine this physical layer design with network coding (NC) and quantify the attainable coding gain. It is shown that the proposed 16-level Star-QAM (16-StQAM) based TC scheme is capable of achieving a coding gain of about 1.5~dB over the TC aided 16-level Differential Phase-Shift Keying (16DPSK) benchmark scheme at a BER of 10^-5. The 16-StQAM based TC assisted scheme is capable of offering another 1.2 dB coding gain, when it is employed in a ´butterfly´ topology network arrangement. When the source and relay nodes are allowed to transmit at different power levels, the two-hop 16-StQAM based TC aided NC scheme outperforms the single-hop 16-StQAM based TC scheme by approximately 2.2 dB.