A robust pilot-assisted equaliser for the partially loaded downlink UMTS TDD

In this paper, we propose a robust pilot-assisted equalisation strategy for the partially loaded time-division duplex (TDD) component of the universal mobile telecommunications system (UMTS). In addition to training-based equalisation performed using the midamble of a data packet, some of the unused spreading codes are exploited to upload pilots in order to perform an additional semi-blind adaptation over the payload of a packet. The latter ensures continuous adaptation and better tracking performance. The affine projection concept along with the concurrent constant modulus algorithm (CMA) and decision-directed (DD) mode are implemented to update the equaliser weights. Computer simulations are used to assess the performance of the proposed adaptation strategy over various UMTS TDD time bursts.