Advanced GF(32) nonbinary LDPC coded modulation with non-uniform 9-QAM outperforming star 8-QAM.

Tao Liu,Changyu Lin,Ivan B Djordjevic

doi:10.1364/oe.24.013866

Abstract

In this paper, we first describe a 9-symbol non-uniform signaling scheme based on Huffman code, in which different symbols are transmitted with different probabilities. By using the Huffman procedure, prefix code is designed to approach the optimal performance. Then, we introduce an algorithm to determine the optimal signal constellation sets for our proposed non-uniform scheme with the criterion of maximizing constellation figure of merit (CFM). The proposed nonuniform polarization multiplexed signaling 9-QAM scheme has the same spectral efficiency as the conventional 8-QAM. Additionally, we propose a specially designed GF(32) nonbinary quasi-cyclic LDPC code for the coded modulation system based on the 9-QAM non-uniform scheme. Further, we study the efficiency of our proposed non-uniform 9-QAM, combined with nonbinary LDPC coding, and demonstrate by Monte Carlo simulation that the proposed GF(23) nonbinary LDPC coded 9-QAM scheme outperforms nonbinary LDPC coded uniform 8-QAM by at least 0.8dB.

Highlights

In the recent years, the exponential Internet traffic growth projections place enormous transmission rate demand on the underlying information infrastructure at every level, from the long haul submarine transmission to optical metro networks [1]
The Monte Carlo simulations indicate that the proposed nonbinary GF(9) Low-density parity-check (LDPC)-coded 9-QAM non-uniform signaling scheme with Huffman code based constellation shaping outperforms the corresponding nonbinary LDPC-coded 8-QAM by at least 0.8 dB
In the BCJR algorithm-based check-node processor, shown in the Fig. 6, the number of states is equal to the finite field size for single parity check (SPC) code and the number of stages is determined by the check node degrees

Summary

Introduction

The exponential Internet traffic growth projections place enormous transmission rate demand on the underlying information infrastructure at every level, from the long haul submarine transmission to optical metro networks [1] To facilitate this trend, the new advanced modulation scheme combined with advanced forward error correction code should be proposed. We introduce an overall search algorithm to determine this 9-point signal constellation by optimizing the constellation figure of merit (CFM) Such designed nonuniform signal constellation sets has been called here 9-QAM, and it has the same spectral efficiency as the conventional 8-QAM. The Monte Carlo simulations indicate that the proposed nonbinary GF(9) LDPC-coded 9-QAM non-uniform signaling scheme with Huffman code based constellation shaping outperforms the corresponding nonbinary LDPC-coded 8-QAM by at least 0.8 dB.

Constellation shaping with Huffman code

Constellation design for non-uniform signaling scheme

Nonbinary quasi-cyclic LDPC coding for 9-QAM

Advanced coded modulation scheme for non-uniform 9-QAM signaling

Simulation results

Concluding remarks