  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.
