Efficient Transmission Technique for MIMO-OFDM Broadcast Channels with Limited Feedback

In multiuser downlink, the use of multiple antennas at the base station and user terminals leads to a great increase in the system throughput. However, this increase is only achieved with proper transmission techniques which schedule the best set of users and distribute resources according to each user's channel condition. In this paper, a multiuser MIMO-OFDM technique based on partial CSI is presented for broadcast channels, which achieves a greatly increased system throughput. In the proposed scheme, the base station schedules transmission to a subset of users and allocates data streams on each antenna and subcarrier to users based on their received partial CSI. A combination of eigenmode transmission and zero-forcing (ZF) receiver processing is used to separate spatial layers on each subcarrier. The results show the proposed scheme's advantage over limited feedback linear ZF receiver processing and frequency division multiplexing (FDM). The feedback overhead of the proposed scheme over realistic channels is significantly reduced compared to the case where only ZF receiver processing is adopted on each subcarrier.