Non-Coherent Signal Detection and Bit Error Rate for an Ambient Backscatter Link under Fast Fading

Abstract

Non-coherent detection is an important component of ambient backscatter communication due to the energy constrained nature of the backscatter devices. This paper provides the first comprehensive performance analysis of non- coherent detection under a fast-varying wireless channel for ambient backscatter communication. In particular, we evaluate the bit error rates (BERs) for two data encoding mechanisms under a new receiver architecture that is based on the direct averaging of the received signal samples. Our results concretely demonstrate the existence of BER floor for a single antenna receiver, which results in poor performance. We further show that a multi-antenna receiver can overcome this drawback by eliminating the interference created by the direct link from the ambient power source that considerably improves the BER of this receiver. This multi-antenna receiver exploits the fact that the time duration of the variation in angle of arrival (AoA) of the communication links in the fast-varying channel is much larger than the coherence period of the small-scale fading, allowing it to track the AoA of the direct link.