Maximizing wireless power transfer using distributed beamforming

We consider the problem of maximizing the total wireless signal power delivered by a distributed antenna array to a receiver where the transmitting nodes each have known frequency-selective channel responses to the receiver and are subject to individual total transmit power constraints. This optimization problem is mathematically quite different from the power maximization problems involving single transmitters or for narrowband systems. We show that the power maximizing solution involves the array nodes performing distributed beam-forming while concentrating their power in a small, finite set of frequencies resulting in an overall received signal consisting of a small number of sinusoidal tones. We derive some properties of the power maximizing solution and describe an iterative algorithm that efficiently computes the solution. We show using numerical simulations that the power maximization problem can yield substantially larger received power compared to alternatives such as a matched filter for frequency-selective channels.