A MIMO parameter estimation model taking Ricean fading channel and stochastically uncorrelated signals into account. Part I. Inherent accuracy limitations

In this paper, a MIMO channel model accounted for Ricean fading and stochastically uncorrelated signals is proposed for the problem of estimating three important parameters of wireless channel, such as the nominal direction, the angular spread and the Ricean factor. Although such a problem formulation captures so many physical scattering features into a parametric channel model, we elaborate the second-order statistic in such a way that the array covariance matrix depends on five parameters. To inspect the achievable performance of parameter estimation, we derive all necessary derivatives of complex gradient matrix to compute the inherent accuracy limitation based on the Cramer-Rao bound. Herein, the estimation possibility and theoretical analysis are pictorially illustrated and therefore able to reflect various relationships.