In this work, we propose an MMSE multiuser detector for asynchronous DS/CDMA systems operating over frequency-selective fading channels. It is shown that computation of a conditional MMSE estimate of the bit to be decoded may be carried out with a computational burden linear in the processing gain N . We also give a closed-form formula for the Error Probability and the Nearfar Resistance of the...

A new multiuser detector for direct-sequence codedivision multiple-access communication systems is described. The proposed detector divides the received signal stream into a number of overlapping windows and decorrelates them window by window. This scheme is justified by an analysis on the convergence and decay rate of the impulse response. Based on the results, a signaladapted criterion is dev...

Most reported multiuser detection techniques for CDMA systems need the channel estimation including the delay spread and the parameters of the multipath channel of the desired user. This paper proposes an intersymbol decorrelating detector that makes use of the cross-correlation matrix constructed by the consecutively received symbols. The proposed detector is attractive for its simplicity beca...

The decorrelating detector and the linear minimum mean-square error (MMSE) detector are known to be effective strategies to counter the presence of multiuser interference in code-division multiple-access channels; in particular, those multiuser detectors provide optimum near-far resistance. When training data sequences are available, the MMSE multiuser detector can be implemented adaptively wit...

In multiuser detection techniques, the maximum likelihood multiuser detector provides the best performance in DS-CDMA systems with impulsive ambient noise. But the high complexity makes it impractical. And therefore, effective sup-optimal detectors in non-Gaussian noise are needed. In this paper, we present two-layer perceptron neural network with back propagation training algorithm as a multiu...

We consider interference rejection for synchronous CDMA frequency non-selective channels using multiuser decision-feedback detector. The average error rate of the ideal two-user decision feedback detector is derived in a closed form and the asymptotic multiuser efficiency is proved to be unity. The effect of error propagation on the actual decision-feedback detectors is investigated through sim...

We consider the problem of multi-user detection for CDMA systems where the codes of some users are known while others are unknown, called semi-blind detectors. An example is at the base station of a cellular communication systems with interference from both in-cell users, with known codes, and out-of-cell users, with unknown codes. In this paper we develop a hybrid semi-blind detector, which is...

This paper presents analysis of a multistage parallel interference canceller receiver for a synchronous multiuser CDMA system. At every stage, new estimates of the multiple access interference are formed from innnitely soft decisions for the users' data. These new estimates are then used to cancel multiple access interference and form new decision statistics for the users' data. We show that in...

The oblique projection supports the framework to resolve a signal space into desired signal and interference subspaces. This paper presents subspace-based detection methods using the oblique projection for the CDMA channel. For the synchronous case, it is shown that this detector represents the geometrical form of the decorrelating detector, and performs a complete rejection of interfering sign...

In a multiple access spread-spectrum communication system, the bit error performance is usually limited by the mutual interference between users. The use of multi-user detection is an effective method to reduce such interference. In this paper, we consider two linear multi-user detectors, namely, decorrelating detector and minimum mean-square-error detector, applied to a multiple access chaotic...