A large system analysis of cooperative multicell downlink system with imperfect CSIT

In this paper, we consider the multi-cell downlink system with multiple base stations (BSs) and multiple single antenna users employing the BS cooperation. The channels between BSs and users have independent spatial correlations. All BSs jointly implement the regularized zero-forcing based on imperfect channel estimation. By utilizing the large dimensional random matrix theory, we first obtain the limiting distribution of the eigenvalues for a class of random Hermitian matrix. Based on this result, we derive a deterministic equivalent of ergodic sum rate for the multi-cell downlink system and obtain the optimal regularization parameter in the special case employing maximize the deterministic equivalent of ergodic sum rate. Numerical results show that the deterministic equivalent are accurate even for finite number of antenna and the channel estimation parameter almost do not affect the accuracy of the approximation.