Testbed for non-coherent zero-feedback distributed beamforming

We present the setup of a complete software-defined radio (SDR) testbed for non-coherent zero-feedback distributed beamforming. Three custom-built, embedded RF transceivers along with a commodity, low-cost SDR commercial receiver are deployed in an indoors lab environment. In sharp contrast with prior art on collaborative beamforming, the proposed scheme assumes no feedback between receiver and transmitters and no access to the transmitters´ local oscillators for carrier phase adjustments. Quite interestingly, frequency offsets are exploited in this work. Zero-feedback beamforming with unsynchronized carriers is experimentally validated in terms of bit-error-rate (BER) and compared with simulation results. To the best of our knowledge, this is the first testbed for demonstrating and evaluating zero-feedback, channel state information (CSI)-free, distributed beamforming.