Joint Interference Cancellation and Symbol Detection for Multistatic Backscatter System

Backscatter communication is a promising passive radio technique for the green Internet of Things (IoT) due to its low cost and low power consumption. However, the limited communication range is a challenging issue because of the double fading of the backscatter link. This paper proposes a multi-static backscatter system in which multiple readers illuminate a tag simultaneously to strengthen the received backscatter signals. In this system, direct links greatly impact the backscatter links, making it difficult to recover the tag information. The interference cancellation (IC) is exploited to cancel out the interference of the direct link and improve the detection probability. Then the expectation maximization (EM) algorithm is used for symbol detection, in which latent variable is introduced to form simpler distribution, and parameters are updated based on their probability. The numerical results verify the better performance of our proposed method.