Accurate downlink channel estimates are calculated based on infrequently transmitted Channel State Information (CSI) feedback data from a UE 20. A plurality of non-uniformly spaced digital CSI feedback samples, representing the frequency response of a downlink communication channel, is received from the UE. The received CSI feedback samples are demodulated and inverse quantized. A time domain tap delay channel model is generated from the inverse quantized CSI feedback samples. The time domain tap delay channel model may be frequency-transformed to obtain a reconstructed frequency response of the downlink communication channel in the frequency domain. Alternatively, channel delays may be estimated based on prior delays and/or known references signals transmitted on the uplink. Channel estimates between CSI reporting instances may be predicted, such as by a sample & hold or a linear predictor. The delays may be presumed fixed, and Kalman filter coefficients evolved over time.