Multi-antenna Non-coherent Detection of Ambient Backscatter under Time-Selective Fading

Abstract

Due to their inherent ability to operate without the channel state information (CSI), non-coherent receivers are highly suitable for ambient backscatter devices, allowing them to co-exist alongside the non-cooperative primary users. In this work, we analyze the performance of an ambient backscatter system employing non-coherent detection in a time-selective fading channel (modeled using the first order autoregressive (AR) process). We characterize the bit error rate (BER) of a multiantenna (MA) receiver by deriving the expression for antenna gain achievable after the direct link (DL) cancellation. In addition, the analysis also captures the additional angular resolution in a MA receiver with more than two antennas, which allows us to ensure reasonable performance even when the angles of arrival (AoAs) of the DL and backscatter link (BL) are almost similar.