Design and Optimization of Hierarchical Demodulator and Decoder for Layered Coded OFDM-IM With NR-LDPC

Abstract

In this paper, we first propose a novel code rate optimized orthogonal frequency division multiplexing with index modulation (OFDM-IM) transceiver architecture based on new radio low-density parity-check (NR-LDPC) coding, referred to as Rate Optimization of Layered Coded OFDM-IM with Hierarchical Demodulator and Decoder (RO-LC-OFDM-IM-HD), which can improve the error performance of system with no spectral efficiency loss. Subsequently, we devise a modified NR-LDPC-based extrinsic information transfer (NR-EXIT) algorithm, to analyze the decoding thresholds of NR-LDPC codes used for index bits and modulation bits in the proposed RO-LC-OFDM-IM-HD. Furthermore, we extend the idea to hierarchical modulation (HM), resulting the rate optimization of multilayered coded HM-OFDM-IM-HD (RO-MLC-HM-OFDM-IM-HD). Simulation results not only indicate that the prosposed RO-LC-OFDM-IM-HD and RO-MLC-HM-OFDM-IM-HD systems outperforms the existing counterparts but also are consistent with the theoretical analyses. Therefore, the proposed RO-LC-OFDM-IM-HD and RO-MLC-HM-OFDM-IM-HD systems are competent to provide a promising solution for high reliability and high throughput wireless communications. INDEX TERMS OFDM with index modulation (OFDM-IM), layered coded, hierarchical demodulator and decoder, NR-LDPC-based extrinsic information transfer (NR-EXIT), hierarchical modulation (HM).