Constellation Precoded Multiple Beamforming

TL;DR

This paper introduces constellation precoded multiple beamforming that achieves full diversity order in MIMO systems with reduced decoding complexity, applicable to both coded and uncoded scenarios, supported by analytical proof.

Contribution

It proposes a novel constellation precoding method for multiple beamforming that guarantees full diversity order with lower decoding complexity.

Findings

Achieves full diversity order with BICM-coded and uncoded SVD systems.

Provides an analytical proof of the full diversity property.

Develops a Sphere Decoding technique with significantly reduced computational complexity.

Abstract

Beamforming techniques that employ Singular Value Decomposition (SVD) are commonly used in Multi-Input Multi-Output (MIMO) wireless communication systems. In the absence of channel coding, when a single symbol is transmitted, these systems achieve the full diversity order provided by the channel; whereas when multiple symbols are simultaneously transmitted, this property is lost. When channel coding is employed, full diversity order can be achieved. For example, when Bit-Interleaved Coded Modulation (BICM) is combined with this technique, full diversity order of NM in an MxN MIMO channel transmitting S parallel streams is possible, provided a condition on S and the BICM convolutional code rate is satisfied. In this paper, we present constellation precoded multiple beamforming which can achieve the full diversity order both with BICM-coded and uncoded SVD systems. We provide an analytical proof of this property. To reduce the computational complexity of Maximum Likelihood (ML) decoding in this system, we employ Sphere Decoding (SD). We report an SD technique that reduces the computational complexity beyond commonly used approaches to SD. This technique achieves several orders of magnitude reduction in computational complexity not only with respect to conventional ML decoding but also, with respect to conventional SD.