Convergence and Density Evolution of a Low-Complexity MIMO Detector based on Forward-Backward Recursion over a Ring

TL;DR

This paper analyzes the convergence and performance of a low-complexity iterative MIMO detector based on belief propagation over a ring, providing theoretical proofs and density evolution analysis for discrete inputs.

Contribution

It offers the first convergence proof for discrete alphabet inputs and develops a density evolution framework for binary inputs in this context.

Findings

Density evolution matches simulation results well.

The algorithm achieves good asymptotic performance in SINR and BER.

Convergence is proven for discrete alphabet inputs.

Abstract

Convergence and density evolution of a low complexity, iterative MIMO detection based on belief propagation (BP) over a ring-type pair-wise graph are presented in this paper. The detection algorithm to be considered is effectively a forward-backward recursion and was originally proposed in [13], where the link level performance and the convergence for Gaussian input were analyzed. Presented here are the convergence proof for discrete alphabet and the density evolution framework for binary input to give an asymptotic performance in terms of average SINR and bit error rate (BER) without channel coding. The BER curve obtained via density evolution shows a good match with simulation results, verifying the effectiveness of the density evolution analysis and the performance of the detection algorithm.