Pilot-Assisted Ambient Backscatter Communications Exploiting Radar Clutter

Radar-generated clutter has been already shown to be a suitable ambient signal for backscatter communications (even assuming no channel state information) primarily due to its relatively large coherence time as compared to the communication rates of interest. The present contribution takes one step forward and introduces semi-blind clutter-enabled multi-source backscatter communications, wherein pilot signals are intermingled with data so as to allow coherent reception. We propose an iterative scheme for joint channel-state estimation and data decoding that relies on regularized least squares and search relaxation and whose complexity per iteration scales only linearly with the data size. The proposed approach is validated through computer simulations, highlighting the gain over the corresponding incoherent architectures.