Long-term transmit beamforming for wireless multicasting

This paper presents a low-complexity iterative algorithm for long-term transmit beamforming in multicast channels. Since it relies only on antenna correlations at the base station, the algorithm requires only infrequent feedback from the users. Multiantenna receivers are not required, but they are transparently accommodated. Simulation results within the context of the UMTS long-term evolution system indicate that, with half-wavelength antenna spacings and a typical power azimuth spectrum, the performance is close to optimal. The specific gains (in average SINR) then depend on the number of transmit antennas and the number of active users.