Efficient channel estimation for implicit mu-mimo

Abstract

Base stations for MIMO wireless systems embodying efficient channel estimation techniques. One illustrative embodiment includes: an array of multiple antennas to exchange uplink and downlink signals with spatially-distributed user terminals; multiple transmit chains, each coupled to one of the multiple antennas by a respective transceiver that also couples that antenna to a respective one of multiple receive chains; and a controller. Each of the receive chains opportunistically derives estimated uplink channel response coefficients from packet headers in the wireless uplink signals, and the controller determines a steering transform based at least in part on the estimated channel response coefficients. The transmit chains apply the steering transform to spatially-distinct downlink signals to produce antenna-specific downlink signals for each antenna in the array. Another illustrative embodiment determines, based at least in part on the estimated channel response coefficients, a mobility indicator for each user terminal, and, based on the mobility indicators, schedules at least one action.