Tag-Side Preprocessing-Aided Spatial Modulation for Backscatter Communication

Backscatter communications (BCs) have gained significant attention in recent years, especially within the realm of Internet of Things (IoT), due to their ability to operate in a battery-free manner, maintaining the low-power and low-cost structure. The utilization of multiple antennas in BC is becoming increasingly recognized as a promising strategy to deliver robust communication performance, particularly in applications with high data demands. In this work, an innovative BC system is introduced which is based on tag-side preprocessing-aided receive spatial modulation (PSM). It includes the design of both zero-forcing (ZF) and minimum mean-squared-error (MMSE) precoders for the transmitter tags, which enables the activation of a single receive antenna at the reader node (RN). Transmitting information via receive antenna indices presents several advantages when compared to other spatial modulation (SM)-based benchmark approaches employed for BC, such as reduced complexity, enhanced energy efficiency, superior bit error rate (BER) performance, and robustness to channel estimation errors. These advantages are shown via both theoretical analysis and also simulation results in this article.