A Performance Bound for Prediction of a Multipath MIMO Channel

Knowledge of future channel conditions can increase the performance of many types of wireless systems. This is especially true for radio channels with multiple transmit and receive antennss, i.e. Multiple-Input Multiple Output (MIMO) systems. This paper derives a performance hound for MIMO channel prediction. It is assumed that p r e diction is based upon estimating a model for the channel and then extrapolating that model to predict future values of the channel. A vector formulation of the Cramhr-Rao bound for functions of parameters is then used to Bnd a lower bound on the prediction error. Numerical evaluation of this bound shows that substantially longer prediction lenghs are possible for MIMO channels than for single antenna channels. An intuitive interpretation of this result is that more of the channel structure is revealed when using multiple antenna at both ends.