Due to the prohibitive complexity of optimal multiuser detection, suboptimal structures are commonly suggested for use in iterative multiuser decoders. The use of suboptimal components in the iterative structure leads to performance losses in terms of system load, bit error rate (BER), and convergence speed. In this paper, we introduce a simple recursive filtering structure into the iterative m...

Multiuser detection techniques provide attractive performance characteristics for CDMA systems. A recently proposed blind adaptive multiuser detector provides near-far resistance without requiring any more information than a conventional detector. In this paper, an optimum and two suboptimum multi-element blind adaptive receivers are proposed. These receivers exploit the spatial distribution of...

| In this paper we show that eecient multiuser receivers result in a cellular capacity that is many times that of conventional cellular systems. We also show that the joint detection of users in soft handover regions dramatically increases system capacity. Although we require a multiuser receiver that can provide single user performance , we show that there is no gain doing so when the number o...

In this paper a soft-in soft-output (SISO) multiuser detection algorithm for synchronous direct sequence-code division multiple access (DS-CDMA) systems operating over a slow Rayleigh fading channel is illustrated. Its derivation is based on the Bayesian Expectation Maximization (BEM) technique. The proposed detector estimates the fading channel in an iterative fashion and produces the a poster...

This letter considers multiuser detection in variable-spreading-length multi-rate direct-sequence code-division multiple-access systems. A two-layer spreading (TLS) code scheme is proposed which facilitates the low-complexity adaptive implementation of linear minimum mean-square error multiuser receivers in a dual-rate system. It is demonstrated via large system analysis and simulation that imp...

Recently, Markov Chain Monte Carlo (MCMC) sampling methods have evolved as new promising solutions to both multiuser and multiple-input multiple-output (MIMO) detection problems. Approaches based on Gibbs sampling as a special type of MCMC methods are well suited due to their good trade-off between performance and complexity. However, it is known that detection methods based on Gibbs sampling s...

We present two detectors which allow multiuser detection without a side channel in a dynamic CDMA system where users are constantly leaving and entering the system. These detectors, the Maximum Likelihood (ML) and Generalized Maximum Likelihood (GML) detectors, optimally detect a new user given only the chip rate and the spreading factor of the new user. Each of these detectors produces maximum...

A novel iterative receiver is proposed for relay-assisted multiuser communications in which multiple users transmit to a destination with the help of a relay and using fast frequency-hopping modulation. Each user employs a channel encoder to protect its information and facilitate interference cancellation at the receiver. The signal received at the relay is either amplified, or partially decode...

We propose a new framework for multiuser detection in fast-fading channels that are encountered in many mobile communication scenarios. Existing multiuser RAKE receivers, developed to combat multipath fading and multiuser interference in slow fading, suffer substantial degradation in performance under fast fading due to errors in channel state estimation. The detectors proposed in this paper em...