Second-order statistics of channel state information in a multi-cell mobile network with fast fading

In this work, the autocorrelation and autocovariance functions of the channel state information (CSI) in a multi-cell mobile network with fast fading is derived analytically. The derivation is based on the Rayleigh fading model. A squared Bessel function is found to be a good approximation of the autocovariance. Simulations confirm both the analytical result and approximation to be accurate for short period. The approximation can be potentially used for a coarse estimation of the moving speed of a mobile user.