Distributed Beamforming using 1 Bit Feedback: from Concept to Realization

We present theoretical and experimental results for a distributed beamforming system based on a simple 1bit feedback algorithm. The algorithm is based on an iterative procedure, that synchronizes multiple transmitters to cooperatively send a common message signal coherently to a receiver, using only a single bit of feedback in each timeslot. Under this scheme, the transmitters make independent, random phase adjustments every timeslot, and retain only those phase adjustments that increase the SNR at the receiver. We describe the design of an experimental prototype to implement the beamforming algorithm, and present measurement data that shows the SNR gains from beamforming. We also analyze the convergence behavior of the procedure mathematically using a statistical approach. We show that the mathematical model gives accurate predictions for the convergence rate in static and time-varying channels, and use the analysis to demonstrate the scalability of the algorithm.