Multi-Tag Backscattering to MIMO Reader: Channel Estimation and Throughput Fairness

TL;DR

This paper explores the use of MIMO technology to enhance channel estimation and throughput fairness in multi-tag backscatter communication, addressing hardware constraints and ambient reflections with novel algorithms and analytical insights.

Contribution

It introduces a new least-squares channel estimation protocol and a low-complexity transceiver design algorithm for multi-tag BSC, improving throughput fairness and robustness.

Findings

Over seven-fold increase in common-backscattered-throughput with proposed methods

Effective mitigation of ambient reflections in channel estimation

Analytical insights into optimal transceiver configurations

Abstract

Green low power networking with the least requirement of dedicated radio resources is need of the hour which has led to the upsurge of backscatter communication (BSC) technology. However, this inherent potential of BSC is challenged by hardware constraints of the underlying tags. We address this timely concern by investigating the practical efficacy of multiple-input-multiple-output (MIMO) technology in overcoming the fundamental limitations of BSC. Specifically, we first introduce a novel least-squares based channel estimation (CE) protocol for multi-tag BSC settings that takes care of both the unintended ambient reflections and the inability of tags in performing estimation by themselves. Then using it, a nontrivial low-complexity algorithm is proposed to obtain the optimal transceiver designs for the multiantenna reader to maximize the minimum value of the lower-bounded backscattered throughput among the single-antenna semi-passive tags. Additional analytical insights on both individually and jointly-optimal precoding vector and detector matrix at the reader are provided by exploring the asymptotically-optimal transceiver designs. Lastly detailed numerical investigation is carried out to validate the theoretical results and quantify the practically realizable throughput fairness. Specifically, more than seven-fold increase in the common-backscattered-throughput among tags as achieved by the proposed designs over the relevant benchmarks corroborates their practical significance.