Concatenated orthogonal space-time block coding with four dimensional 8-PSK trellis coded modulation over fading channels in absence of channel state information

Abstract

In this paper, new non-coherent space-time block code (STBC) based on concatenated inner STBC and outer four dimensional 8-PSK trellis coded modulation (4D-8-PSK-TCM) encoder is designed for quasi static Rayleigh fading channel. The code design method achieves a diversity order of 4 with two transmit and two receive antennas. Firstly, we demonstrate that the proposed 4D-TCM-STBC scheme with perfect CSI significantly outperforms the traditional STBC schemes under the same spatial diversity and signal constellation. Then, the Rayleigh fading channel parameters are estimated using a pilot symbols based least squares (LS) estimator. Simulation results demonstrate the good performance of the proposed non-coherent scheme against concatenated STBC and conventional TCM already published. Unfortunately, due to the weak convergence of LS estimator with reduced pilot symbols number, BER loss against coherent system is still observed but stands much smaller than BER loss shown by competitive schemes.