On the sum rate of MIMO Nakagami-m fading channels with MMSE receivers

In this paper, we elaborate on the ergodic sum rate of multiple-input multiple-output (MIMO) Nakagami-m fading channels with linear minimum mean square error (MMSE) receivers. For dual transmit antenna configurations, we present new, closed-form upper bounds on the ergodic sum rate of MMSE receivers. Moreover, we derive exact expressions for the two key parameters dictating the sum rate behavior in the low signal to noise ratio (SNR) regime, i.e., minimum energy per information bit to reliably convey any positive rate and the wideband slope. Our analytical results demonstrate the sub-optimality of linear MMSE receivers and provide useful insights into the impact of model parameters (e.g. number of antennas, fading parameters).