1. A method comprising: determining a precoding matrix index (PMI) for a serving base station and one or more cooperative base stations by a mobile station to optimize system performance for multi-BS multiple-input multiple-output (MIMO) in a cellular orthogonal frequency division multiple access (OFDMA) system; determining a plurality of corresponding weight factors for each of the base stations to further optimize system performance; and transmitting the PMI and the weight factors to the serving base station, wherein the PMI and the weight factors are shared between the serving base station and at least one of the one or more cooperative base stations.