Messages containing interference vectors are transmitted efficiently to user equipments over a downlink channel. A pre-coding indicator channel is used for transmission in an over-the-air packet-based communication system. A table of pre-coding matrix indices or pre-coding vector information is transmitted to user equipments configured in a spatially multiplexed multiple user MIMO configuration. The UEs receive the pre-coding vector information that allows them to determine the pre-coding vectors used to communicate in the downlink direction from a MIMO base station to other MIMO UEs in the cell or system. The UEs use this information to actively suppress inter-user interference.