GC-LDPC Coded Modulation

Abstract

Due to the scarcity of spectrum resources, the combination of forward error correction (FEC) code and high-order modulation, i.e. coded-modulation (CM) is essential to the various high data rate multimedia communication services. In this paper, we propose a new CM scheme, namely the globally coupled (GC) low-density parity check (LDPC) CM where we choose GC-LDPC code as the FEC code and regular rectangular quadrature amplitude modulation (QAM) as the high order modulation. To guarantee the code with at least grith 8, the greatest common division-based method is used to constructe the GC-LDPC code. Simulation results show that, although the GC-LDPC code has poor performance under QPSK modulation compared with the LDPC code defined in 5G (5G-LDPC), the proposed GC-LDPC CM outperforms 5G-LPDC CM under 64QAM modulation about 0.5dB. The EXIT charts also theoretically demonstrate the GC-LDPC code the significant gain. Considering other advantages of GC-LDPC such as flexible rate design, parallel decoding and etc., the proposed GC-LDPC CM is attractive to multimedia communication systems which generally requires high spectral efficiency.