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On Signal Space Diversity for non binary coded modulation schemes

In this paper, we study high-spectral efficiency and high-order diversity communications for next generation broad-casting systems. In this context, rotating a Quadrature Amplitude Modulation constellation with a Signal Space Diversity (SSD) technique is known to improve the decoding performance of the communication system over the Rayleigh fading channel. In this work, we consider the SSD technique applied to coded modulation schemes with the novelty of selecting the rotation angle from the analysis of the mutual information variations. In this context, it is known that coding modulation outperforms bit-interleaved coded modulation, but we show that coded modulation has also an extra advantage: the optimal rotation angle is only marginally impacted by the signal to noise ratio and the erasure rate of the fast Rayleigh fading channel. This opens the door to a robust coded modulation scheme particularly suited for broadcasting applications. Simulation results confirm the theoretical study with a gain of up to 1.2 dB when comparing to the DVB-T2 standard.