Analytical approximation of ZF Ricean rate in massive MIMO channels

The analytical approximation of the Ricean channel (non-central Wishart) matrix is often analysed with the central Wishart matrix. This method falls short of exploiting the non-zero Ricean channel mean to calculate the average zero-forcing (ZF) massive multiple-input and multiple-output(MIMO) ergodic rate. In this Letter, the authors develop a new approach to accurately approximate the inverse Ricean channel, and determine the main diagonal. After which, optimal power allocation is used to maximise the ergodic rate. Numerical results validate the accuracy of the proposed approximation with the ideal channel.