A Comparison of Normalizations for ZF Precoded MU-MIMO Systems in Multipath Fading Channels

We compare two commonly used normalizations for zero-forcing (ZF) precoded multi-user multi-input-multi-output (MU-MIMO) systems: equal transmit power (ETP) and equal receive power (ERP) normalization. Both have been proposed in the literature, but with no comparison of the performance in multipath fading channels. We show analytically, and through simulations, that the ETP normalization leads to a higher total received power at the users and a higher sum rate. We also present simulation results in a multipath fading channel to corroborate the analysis and observe that the performance spread among users increases as the delay spread decreases with ETP normalization. This can be used to choose the appropriate normalization in a particular multipath scenario.