Date Added: Apr 2011
In this paper, the authors investigate the issue of exploiting switched beamforming antennas to improve multicast transmission in wireless networks. Under the practical assumptions that different beams may have arbitrary overlapping patterns and that each user can receive data at different rates under different beams, they formulate the problem as minimizing the total multicast delay subject to the constraint that all users need to be covered. They prove that the problem is NP-hard and propose a greedy algorithm that achieves log(J) approximation guarantee where J is the number of clients. Measurements in both indoor and outdoor experiments validate their assumptions on the beamforming model.