Design of Protograph LDPC-Coded MIMO-VLC Systems with Generalized Spatial Modulation

This paper investigates the bit-interleaved coded generalized spatial modulation(BICGSM)with iterative decoding(BICGSM-ID)for multiple-input multiple-output(MIMO)visible light communications(VLC).In the BICGSM-ID scheme,the information bits conveyed by the signal-domain(SiD)symbols and the spatial-domain(SpD)light emitting diode(LED)-index patterns are coded by a protograph low-density parity-check(P-LDPC)code.Specifically,we propose a signal-domain symbol expanding and re-allocating(SSER)method for constructing a type of novel gen-eralized spatial modulation(GSM)constellations,re-ferred to as SSERGSM constellations,so as to boost the performance of the BICGSM-ID MIMO-VLC sys-tems.Moreover,by applying a modified PEXIT(MPEXIT)algorithm,we further design a family of rate-compatible P-LDPC codes,referred to as en-hanced accumulate-repeat-accumulate(EARA)codes,which possess both excellent decoding thresholds and linear-minimum-distance-growth property.Both anal-ysis and simulation results illustrate that the proposed SSERGSM constellations and P-LDPC codes can re-markably improve the convergence and decoding per-formance of MIMO-VLC systems.Therefore,the pro-posed P-LDPC-coded SSERGSM-mapped BICGSM-ID configuration is envisioned as a promising trans-mission solution to satisfy the high-throughput re-quirement of MIMO-VLC applications.