This paper is concerned with the maximization of the weighted sum-rate in the multicell MIMO Multiple Access Channel (MAC). Considered is the multicell network operating on the same frequency channel with multiple Mobile Stations (MS) per cell. Assuming the interference coordination mode in the multicell network, each Base-Station (BS) only decodes the signals for the MSs within its cell. However, the uplink covariance matrices at the MSs are jointly designed between the BSs in order to optimize the network-wide weighted sum-rate. Since this optimization is shown to be a non-convex problem, obtaining its globally optimal solution is very hard.