Multi-edge Low-density Parity-check Coded Modulation

Abstract

A method for designing low-density parity-check (LDPC) codes for bandwidth-efficient high-order coded modulation is proposed. Code structure utilizes the multi-edge-type LDPC code ensemble to achieve an improved match between codeword bit protection ca- pabilities and modulation bit-channel capacities over existing LDPC coded modulation techniques. The multi-dimensional EXIT vector field for the specific multi-edge parame- terization is developed for the analysis and design of code ensembles. A multi-dimensional EXIT decoding convergence condition is derived to enable efficient optimization. Code design results in terms of ensemble thresholds and finite-length Monte-Carlo simulations indicate that the new technique improves on the state-of-the-art performance, with sig- nificantly lower design and implementation complexity.