Capacity, Convergence, and Complexity Improvements for LDPC-Coded MIMO-VLC Systems With Generalized Spatial Modulation

This paper is centered on multiple-input multiple-output visible light communication (MIMO-VLC) systems with protograph-based low-density parity-check (P-LDPC) codes. We propose a two-step design method, which is composed of spatial-domain (SpD)-based Gray-like (GL) principle and signal-domain (SiD)-based energy-optimization (EO) principle, to construct a novel class of generalized spatial modulation (GSM) schemes, referred to as GLEOGSM schemes, to enhance the system performance. We also introduce a novel internal-stopping (IS) principle into the conventional joint detection and decoding (JDD) architecture, the resultant IS-aided JDD (IS-JDD) algorithm significantly reduces the computational overhead. Inspired by the proposed IS-JDD architecture, we further conceive a low-complexity IS-aided extrinsic-information-transfer (IS-EXIT) algorithm to analyze the convergence performance of P-LDPC-coded MIMO-VLC systems. Both theoretical and simulation results verify that our proposed designs can remarkably outperform the existing benchmark schemes in terms of capacity, convergence and complexity.