Optimized linear receivers and power allocation for two multi-user MIMO downlink schemes with linear precoding

In this paper, we propose some ameliorations and a comparison of linear closed form precoding techniques for Multi-User MIMO (MU-MIMO) systems. In fact, the sum-rate, one of the most important parameters in the design of communication systems, is analysed through the study of two existing linear precoding schemes. These schemes are the PU-MMSE precoder named PU-MMSE and the Max SJNR scheme (Signal to Jamming plus Noise ratio). Two major improvements are introduced to the existing algorithms in order to increase the throughput of the system. The first modification consists in proposing an alternate receiver namely an MMSE receiver to enhance the performance. The second modification consists in introducing a power optimization involving a user selection procedure at the transmitter. Finally, these improvements have been validated by means of simulations. Indeed, important performance improvements are obtained thanks to these modifications. Moreover, this allows us to perform a comparison of these two linear precoding techniques. The comparision demonstrates that the SJNR precoder is offering better system throughputs than the PU-MMSE precoder.