A wireless communication network processes composite loop-back signals received at one or more network antennas from a plurality of mobile stations, each transmitting an individual, mobile-specific loop-back signal. Using its knowledge of the prior network-transmitted signal(s) from which the mobile stations derive their individual loop-back signals, and its knowledge of the mobile-specific loop-back signal modifications made by each of the mobile stations, the network derives mobile-specific downlink channel information based on processing the composite loop-back signals. That is, use of the mobile-specific loop-back signals enables the network to determine downlink channel estimates as between each participating network antenna and each participating mobile station to be used for transmit signal interference and/or power pre-compensation, for example. Mobile stations incorporate loop-back signal sample processors used to impart mobile-specific modifications to signal samples obtained from network-transmitted signals. The modified signal samples, thus "imprinted," are then transmitted back to the network.