Constellation Precoded Beamforming

TL;DR

This paper introduces a constellation precoding technique for MIMO beamforming that enables uncoded multiple beamforming to achieve full diversity, outperforming single beamforming at the same data rate.

Contribution

It demonstrates that a carefully designed constellation precoder can restore full diversity in uncoded multiple beamforming and improve performance over single beamforming without precoding.

Findings

Precoded multiple beamforming achieves full diversity.

Partially precoded beamforming outperforms unprecoded in diversity.

Simulation results confirm theoretical analysis.

Abstract

We present and analyze the performance of constellation precoded beamforming. This multi-input multi-output transmission technique is based on the singular value decomposition of a channel matrix. In this work, the beamformer is precoded to improve its diversity performance. It was shown previously that while single beamforming achieves full diversity without channel coding, multiple beamforming results in diversity loss. In this paper, we show that a properly designed constellation precoder makes uncoded multiple beamforming achieve full diversity order. We also show that partially precoded multiple beamforming gets better diversity order than multiple beamforming without constellation precoder if the subchannels to be precoded are properly chosen. We propose several criteria to design the constellation precoder. Simulation results match the analysis, and show that precoded multiple beamforming actually outperforms single beamforming without precoding at the same system data rate while achieving full diversity order.