A distributed transmit beamforming technique is described for a scenario with two or more transmit nodes and one intended receiver. The protocol includes a measurement epoch, feedback from the intended receiver to the transmit nodes, and a beamforming epoch. The intended receiver tracks the clock and kinematic parameters of the independent transmit nodes and coordinates the transmit nodes by feeding back state predictions which are then used as phase corrections to facilitate passband phase and frequency alignment at the receiver. A three-state dynamic model is developed to describe the stochastic kinematics and clock evolution of each transmit node relative to the frame of the receiver/coordinator. Steady-state analysis techniques are used to analytically predict the tracking performance as well as the beamforming gain as a function of the system parameters. Numerical results show that near-ideal beamforming performance can be achieved if the period between successive observations at the receiver/coordinator is sufficiently small.
['D. Richard Brown', 'Patrick Bidigare', 'Upamanyu Madhow']
Receiver-coordinated distributed transmit beamforming with kinematic tracking