We consider the problem of designing a multiuser detector for synchronous code−division multiple−access (CDMA) systems, where the signature matrix is subject to {\em structured} uncertainties. We seek the robust multiuser detector that minimizes the worst−case bit error probability (BER) over all possible values of the unknown signature matrix. We first develop the exact robust multiuser detect...

We present a framework for analyzing multiuser detectors in the context of statistical mechanics. A multiuser detector is shown to be equivalent to a conditional mean estimator which finds the mean value of the stochastic output of a so-called Bayes retrochannel. The Bayes retrochannel is equivalent to a spin glass in the sense that the distribution of its stochastic output conditioned on the r...

In a direct sequence code division multiple access (CDMA) system, a xed bandwidth expansion could be allocated to either error correcting coding or modulation signal spreading. The role of coding in CDMA systems that employ multiuser detection is explored here. A comparison is made between the maximum throughputs (in bits/chip or bits/s/Hz) achievable using multiuser detection and single-user d...

In this paper a preprocessing algorithm for binary quadratic programming problems is presented. For some types of binary quadratic programming problems, the algorithm can compute the optimal value for some or all integer variables without approximations in polynomial time. When the optimal multiuser detection problem is formulated as a maximum likelihood problem, a binary quadratic programming ...

We investigate the use of an antenna array at the receiver in FDMA/TDMA systems, to let several users share one communication channel within a cell. A decision feedback equalizer which simultaneously detects all incoming signals (multiuser detection) is compared to a set of decision feedback equalizers, each detecting one signal and rejecting the remaining as interference. We also introduce the...

We investigate the characteristics of the received signal as trilinear model for multi-carrier code division multiple access (MC-CDMA) system with antenna array, and propose a blind multiuser detection method for MC-CDMA system in this paper. The trilinear-based multiuser detection algorithm (Trilinear-MUDE) that we presented exploits the versatile diversity in MC-CDMA system while require neit...

In view of the lack o realism of an AWGN model for ambient noise arising in many practical channels in which multiuser detection techniques may be applied, natural questions arise concerning the applicability, robustness, and performance of multiuser detection techniques for non-Gaussian multiple-access channels. In this paper, we consider the multiple access mitigation problem in DS-CDMA chann...

In multiple-access communication systems co-channel interference can be mitigated by applying multiuser detection instead of treating the interference as additive noise [1]. In this paper we focus on downlink operation in a GSM-like TDMA network and investigate multiuser channel estimation and data symbol detection of two users that share the same physical channel in two adjacent cells. Such a ...

A multiuser detector for direct-sequence code-division multiple-access systems based on particle swarm optimization (PSO) algorithm is proposed. To work around potentially computational intractability, the proposed scheme exploits heuristics in consideration of both global and local exploration maximum likelihood (ML). Computer simulation demonstrates that the proposed detector offers near-opti...

We consider the problem of multiuser detection for DSCDMA in doubly-selective (timeand frequency-selective) channels, and propose a time-varying multiuser detector (TVMUD) to solve this problem. Using a basis expansion model (BEM) to model the doubly-selective channel and the TVMUD, we derive a closed-form expression for the BEM coefficients of the TV-MUD as a function of the BEM coefficients o...