Iterative Detection and LDPC Decoding Algorithms for MIMO Systems in Block-Fading Channels

TL;DR

This paper introduces an iterative detection and decoding scheme using LDPC codes for MIMO systems in block-fading and fast fading channels, achieving significant BER improvements through a novel soft information processing strategy.

Contribution

It develops a new IDD receiver with a soft information strategy that exploits code structure and LLR behavior, enhancing BER performance in challenging fading environments.

Findings

Up to 3dB BER gain in block-fading channels

Up to 1dB BER gain in fast fading channels

Effective use of Root-Check LDPC codes in iterative decoding

Abstract

We propose an Iterative Detection and Decoding (IDD) scheme with Low Density Parity Check (LDPC) codes for Multiple Input Multiple Output (MIMO) systems for block-fading $F = 2$ and fast fading Rayleigh channels. An IDD receiver with soft information processing that exploits the code structure and the behaviour of the log likelihood ratios (LLR)'s is developed. Minimum Mean Square Error (MMSE) with Successive Interference Cancellation (SIC) and with Parallel Interference Cancellation (PIC) schemes are considered. The soft \textit{a posteriori} output of the decoder in a block-fading channel with Root-Check LDPC codes has allowed us to create a new strategy to improve the Bit Error Rate (BER) of a MIMO IDD scheme. Our proposed strategy in some scenarios has resulted in up to 3dB of gain in terms of BER for block-fading channels and up to 1dB in fast fading channels.