An asymptotic analysis of capacity in narrowband MIMO channels

Multi input multi output (MIMO) channels under a particular set of correlated channel assumptions, viz. the product correlation, have been shown to differ from i.i.d. channels essentially in the scaling factor of capacity increase [Chen-Nee Chuah, et al. (2002)]. Using a scattering environment based channel representation, we extend the paradigm of capacity scaling to a regime where it saturates or scales depending on how the environment grows with the number of antennas. We also show how the capacity per dB at low SNR´s depends on the channel parameters. Based on some (preliminary) results on the convergence rate of the empirical spectral distribution function of an i.i.d. channel we present a rigorous understanding of the notion of ´fast convergence´.