Non-Cooperative Game for Equal-Gain Beamforming in Multiuser OFDM Systems

Spatial division multiple access can be used to boost spectrum efficiency if perfect channel information is available at the transmitter. By using equal-gain beamforming, this paper reformulates the difficult non-convex optimization problem of finding the optimal multiuser beamforming vectors into a convex one. Consequently, the Nash equilibrium solution can be reached based on a non- cooperative game, where each receiver feedbacks its selected beamforming vector without sharing information with the others. This paper verifies the performance over spatial correlated, multipath, time-varying Rayleigh fading channels for downlink orthogonal frequency division multiplexing systems. Based on long-term beamforming, the proposed algorithm outperforms the conventional approach in terms of received SINR, besides the reduced complexity.