  This paper considers the joint transceiver design for downlink multiuser
multiple-input single-output (MISO) systems with coordinated base stations
(BSs) where imperfect channel state information (CSI) is available at the BSs
and mobile stations (MSs). By incorporating antenna correlation at the BSs and
taking channel estimation errors into account, we solve two robust design
problems: 1) minimizing the weighted sum of meansquare- error (MSE) with per BS
antenna power constraint, and 2) minimizing the total power of all BSs with per
user MSE target and per BS antenna power constraints. These problems are solved
as follows. First, for fixed receivers, we propose centralized and novel
computationally efficient distributed algorithms to jointly optimize the
precoders of all users. Our centralized algorithms employ the second-order-cone
programming (SOCP) approach, whereas, our novel distributed algorithms use the
Lagrangian dual decomposition, modified matrix fractional minimization and an
iterative method. Second, for fixed BS precoders, the receivers are updated by
the minimum mean-square-error (MMSE) criterion. These two steps are repeated
until convergence is achieved. In all of our simulation results, we have
observed that the proposed distributed algorithms achieve the same performance
as that of the centralized algorithms. Moreover, computer simulations verify
the robustness of the proposed robust designs compared to the non-robust/naive
designs.
