Adaptive block-equalizers for the UTRA-FDD downlink

Novel and simple concepts for adaptive block-equalizers to be used in the downlink of the Universal Mobile Telecommunication System (UMTS) terrestrial radio access (UTRA) with frequency-division duplex (FDD) are presented. The adaptation of the block-equalizers using modified least-squares (LS) or minimum mean-square error (MMSE) schemes is based on the continuously transmitted, code-multiplexed common pilot channel (CPICH). In contrast to classical adaptive filter approaches, the number of coefficients to be adapted corresponds to the number of propagation channel paths and is thus independent of the chosen block size. In time-varying multipath propagation scenarios, a remarkable performance gain in terms of uncoded bit-error rate is obtained with respect to block-equalizers constructed using conventionally estimated channel impulse responses.