Mahmoud Hadef

A pilot-assisted equalisation scheme for the UMTS-TDD downlink with partial loading

We address a pilot-assisted channel equalisation strategy for the partially loaded downlink time-division duplex (TDD) component of the universal mobile telecommunication system (UMTS). Adaptation is performed by minimising a hybrid cost function based on the constant modulus (CM) criterion for all active users and a mean square error (MSE) criterion for both absent users and pilot signals. Computer simulations are used to assess the performance of the equalisation strategy under various partially loaded conditions.

Concurrent constant modulus algorithm and decision directed scheme for synchronous DS_CDMA equalisation

In this paper, we derive a concurrent constant modulus algorithm (CMA) and decision directed (DD) scheme for blind multiuser equalization-suitable for downlink DS-CDMA systems. Adaptation is performed by concurrently minimizing two cost functions based on either a CM criterion or a DD scheme for all active users. Computer simulations are used to assess the performance of the algorithm

Adaptive blind multiuser equalizer based on pdf matching

In this paper, we propose a new adaptive technique for blind multiuser equalisation. The proposed approach is based on fitting the probability density function (pdf) of the equalizer output to the desired pdf of the corresponding symbol alphabet. The underlying pdf at the equalizer output is estimated by means of the Parzen Window method. A switch between blind and Decision Directed adaptation is possible by manipulating the kernal size of the Parzen Window Estimator. The cost function of the proposed technique can be measured by a stochastic gradient descent approach. The performance of the proposed adaptation strategy is assessed by a number of simulations, and benchmarked against Firmer-CMA under QPSK modulation.

A New UMTS TDD Burst Structure With a Semi-Blind Equalisation Scheme

In this paper, we propose a new homogeneous burst structure for the time-division duplex (TDD) component of the universal mobile telecommunication system (UMTS). The midamble period is removed and replaced by a data field to enhance the systems spectrum efficiency. Alternatively, a pilot signal is loaded into one of these bursts over each time slot, in order to ensure a continuous channel tracking by means of a pilot-assisted adaptation. Computer simulations are used to assess the performance of the adaptation strategy over the proposed time burst

Affine Projection Algorithm for Blind Multiuser Equalisation of Downlink DS-CDMA System

In this paper, we derive an affine projection algorithm (APA) for blind multiuser equalisation, suitable for downlink DS-CDMA systems. Adaptation is performed by minimising a cost function based on the constant modulus (CM) criterion for all users. Computer simulations are used to assess the performance of the algorithm