Distribution of eigenvalues for 2×N MIMO channel capacity based on urban microcell measurements

In this paper, we investigate the distribution of eigenvalues of HH^† where the H and superscript ^† denote the MIMO (multiple input multiple output) channel matrix measured in urban microcell and conjugation and transposition. Our channel sounding system is the BECS (band exploration and channel sounding) 2006, which works at a carrier frequency of 3.705 GHz with 100 MHz bandwidth. From the measured data, It is observed that the distribution of eigenvalues of HH^† almost fits with Gamma distribution. We derive simple expressions of mean and variance of eigenvalues, which are functions of the absolute values of Tx (transmit) and Rx (receive) antenna correlation coefficients and the number of Rx antennas. Using the expressions of mean and variance, we then model the eigenvalues as Gamma distributed random variables for 2×N (i.e., 2 Tx and N Rx antennas) MIMO channel capacity. Monte Carlo simulations are used to generate eigenvalue realizations according to the model. The results are compared with the measure data and good agreements are found.