Abdelouahab Bentrcia

A New Linear Group-Wise SIC Multiuser Detector

In this work, we introduce a new linear group-wise SIC multi-user detector that can converge to either the decorrelator or the least minimum mean-square error (LMMSE) detector. We study the convergence behavior of the proposed scheme and show that the latter is equivalent to the block Gauss-Seidel iterative method if the group-detection scheme used is the decorrelator detector. Moreover, we prove that the latter is convergent if the group-detection matrix is positive definite. Our simulation results are in excellent agreement with the proposed theory

A New Linear Group-Wise Parallel Interference Cancellation Detector

In this paper, a new linear group-wise parallel interference cancellation (LGPIC) detector is proposed. Four different group-detection schemes are derived, namely, the linear group matched filter PIC (LGMF-PIC) detector, the linear group decorrelator PIC (LGDEC-PIC) detector, the linear group minimum mean square error PIC (LGMMSE-PIC) detector and the linear group parallel interference cancellation weighted PIC (LGPIC-PIC) detector. The convergence behavior of the proposed detector is analyzed and conditions of convergence are derived. Finally, extensive simulations regarding the convergence behavior and the effect of the grouping on the convergence behavior of the proposed LGPIC detector are conducted.

A new ordering and grouping algorithm for the linear weighted group matched filter successive interference cancellation detector

A linear group-wise successive interference canceller in a synchronous code-division multiple-access system (CDMA) is considered in this paper. The proposed hybrid detector that combines successive and parallel cancellation techniques makes use of advantages offered by the two techniques. The convergence of the hybrid interference cancellation (HIC) detector is guaranteed by an adjustable parameter that depends upon the largest eigenvalue of the systems transition matrix. Since the largest eigenvalue is difficult to estimate, an upper bound is necessary for successful convergence. For this reason, a new upper bound for the maximum eigenvalue of the systems transition matrix was developed. Moreover, a new ordering and grouping algorithm that results in a higher convergence speed is proposed. Simulation results show that a significant improvement in performance is obtained using this technique.

The effect of users' grouping on the convergence behavior of the linear group-wise SIC

In this paper, we use the whitening filter theory to classify different linear group-wise successive interference cancellation multiuser detectors. Three major categories are distinguished namely the whitening filter, the partially whitening filter and the nonwhitening filter based group-wise successive interference cancellation detectors. Using the same theory, we study the effect of users grouping on their convergence behavior. Our analyses are verified through simulation.

An improved HIC using a new ordering and grouping algorithm

A linear group-wise successive interference canceller in a synchronous CDMA system is considered in this work. The proposed hybrid detector that combines successive and parallel cancellation techniques makes use of advantages offered by the two techniques. The convergence of the hybrid interference cancellation (HIC) detector is guaranteed by an adjustable parameter that depends upon the largest eigenvalue of the systems transition matrix. Since this largest eigenvalue is difficult to estimate, an upper bound is necessary for successful convergence. For this reason, we propose a new ordering and grouping algorithm that yields a tight upper bound, which, in turn, results in a higher convergence speed. Simulation results show that a significant improvement in performance is obtained when this technique is used.

Analysis of the Linear GSIC Multiuser Detector Using a Matrix Iterative Approach

In this work, we use a new approach that relies on the theory of matrix iterative analysis to study the convergence behavior of the linear group-wise successive interference cancellation (GSIC) detector. Particularly, we show that the linear GSIC detector is in fact a realization of a modified block successive over-relaxation (BSOR) iterative method where the relaxation factor is a matrix instead of scalar. Consequently, to study the convergence behavior of the GSIC detector, we propose two new corollaries that extend the famous work of Kahan (Varga, Matrix iterative analysis, 2000) to the case where the relaxation factor is a matrix instead of a scalar. Using the two new corollaries we develop two new conditions of convergence for the linear GSIC detector. Simulation results are in excellent agreement with theory.

A new approach to the analysis of the linear group-wise parallel interference cancellation detector

In this paper, the recently proposed linear group-wise parallel interference cancellation (LGPIC) detector is identified as a preconditioned block Richardson iterative method. This facilitates considerably the analysis of the convergence behavior of different group-detection schemes. Moreover, by using this approach, the effect of grouping is easily studied as well. Finally, simulation results conducted are in excellent agreement with the theory.

Low-complexity linear group-SIC detectors

In this paper, we consider a linear group polynomial expansion successive interference cancellation (GPE-SIC) detector in a synchronous CDMA system. It is a hybrid detector, which combines parallel and successive cancellation techniques in order to extract the advantages of both schemes. We use the fact that even if the cross-correlation matrix of the system is not diagonal dominant, the sub-matrices corresponding to different groups can be forced to be diagonal dominant by suitable grouping of users to approximate the decorrelator/MMSE detector by a low-complexity polynomial expansion detector. The latter is computationally very efficient if the cross-correlation matrix of users within the same group is diagonal dominant. n n n nSimulation results showed that the (GPE-SIC) detector has the same performance as the linear group decorrelator successive interference cancellation (GDEC-SIC) detector but with low-computational complexity. Copyright

The effect of users' grouping on the linear group-wise successive interference cancellation detectors

We present a generalized linear multistage hybrid multiuser detector for the uplink channel in a CDMA system. We discuss new results that facilitate the analysis of multistage multiuser detectors. We validate our work by extensive simulation showing the convergence behavior of the hybrid multiuser detector for different users grouping.

A Wideband BSOR-GSIC Multiuser Detector for Long-Code CDMA Systems

In this work, a new wideband linear group-wise SIC (GSIC) multi-user scheme that is asymptotically equivalent to the block successive over-relaxation (BSOR) iteration, which is known to outperform the conventional block Gauss-Seidel iteration by an order of magnitude in terms of convergence speed, is proposed. The proposed scheme uses directly the spreading codes and doesnt require the calculation of the cross-correlation matrix which results in a considerable reduction in computational complexity. Hence it is suitable for long-code CDMA systems such as IS-95 and UMTS where the cross-correlation matrix is changing every symbol. We determine the condition of convergence of the proposed scheme and prove that it converges to the decorrelator detector if the over-relaxation factor is within the interval (0, 2). Simulation results are in excellent agreement with theory.