On Fast-Decodable Space-Time Block Codes

TL;DR

This paper develops conditions for fast decoding of full-rate space-time block codes in MIMO systems, introduces a new 4x2 code with improved performance, and provides a sphere decoding algorithm for QAM.

Contribution

It derives unified conditions for reduced-complexity decoding, analyzes existing codes, and proposes a novel 4x2 code with superior performance.

Findings

Reduced-complexity sphere decoding algorithm for QAM.

New 4x2 STBC outperforms previous codes for certain constellations.

Unified analysis of 2x2 STBC families for fast decoding.

Abstract

We focus on full-rate, fast-decodable space-time block codes (STBCs) for 2x2 and 4x2 multiple-input multiple-output (MIMO) transmission. We first derive conditions for reduced-complexity maximum-likelihood decoding, and apply them to a unified analysis of two families of 2x2 STBCs that were recently proposed. In particular, we describe a reduced-complexity sphere decoding algorithm suitable for QAM signal constellations. Next, we derive a novel reduced-complexity 4x2 STBC, and show that it outperforms all previously known codes with certain constellations.