Beam-forming Method for SDMA Systems Reducing Feed-back Information

摘要

In frequency division duplex (FDD) systems, since the responses in the downlink channel are generally different from those in the uplink, downlink parameters should be estimated by using a feedback approach especially in space-division-multiple-access (SDMA) systems. However, as the number of antenna elements increases, more information bits in the uplink and longer probing periods in the channel response estimation in the downlink are required to feed back all channel responses. This affects the throughput performance significantly in the uplink and downlink. In this paper, we propose new smart antennas and a beam control method for downlink SDMA systems to reduce amount of feedback information. Some simulation results show that proposed method reduces the feedback information almost 1/3, when the number of antenna elements is 8 and the number of users is 3.