Detection of Ambient Backscatter Signals from Multiple-Antenna Tags

Ambient backscatter has been introduced as an potential technology that is effective to address communication and energy problems for battery-free devices. Most existing studies about ambient backscatter are based on the assumption of single antenna at each tag. In this paper, we show that multiple-antenna tags are practically useful and then investigate signal detection in ambient backscatter communication systems with multiple-antenna tags. Multiple antennas indicate multiple channel parameters between the tag and the reader, which constitutes the main challenge for signal detection because the tag has limited power and can transmit few training symbols. Therefore, we design a blind detector for the reader to recover tag signals without not only all channel state information (CSI) but also the knowledge of RF (radio frequency) signal power and noise variance The optimal antenna selection algorithm is also provided. Finally, we study the performance of the proposed detector by simulation examples.