Feedback reduction in uplink MIMO OFDM systems by chunk optimization

Abstract

The performance of multiuser MIMO systems can be significantly increased by channel-aware scheduling and signal processing at the transmitters based on channel state information. In the multipleantennauplink multicarrier scenario, the base station decides centrally on the optimal signal processingand spectral power allocation as well as scheduling. An interesting challenge is the reduction of theoverhead in order to inform the mobiles about their transmit strategies. In this work, we propose toreduce the feedback by chunk processing and quantization. We maximize the weighted sum rate ofa MIMO OFDM MAC under individual power constraints and chunk size constraints. An efficientiterative algorithm is developed and convergence is proved. The feedback overhead as a function of thechunk size is considered in the rate computation and the optimal chunk size is determined by numericalsimulations for various channel models. Finally, the issues of finite modulation and coding schemes aswell as quantization of the precoding matrices are addressed.