Journal ArticleDOI
Optimum multiuser detection is tractable for synchronous CDMA systems using m-sequences
Sennur Ulukus,Roy D. Yates +1 more
TLDR
It is shown that the optimum multiuser detection problem for a synchronous code-division multiple access (CDMA) system is equivalent to the minimum capacity cut problem in a related network and an optimumMultiuser Detection algorithm with polynomial computational complexity for a certain class of signature sequences is proposed.Abstract:
The optimum multiuser detection problem was shown to be NP-hard, i.e., its computational complexity increases exponentially with the number of users (Verdu 1986, 1989). In this letter, we show that the optimum multiuser detection problem for a synchronous code-division multiple access (CDMA) system is equivalent to the minimum capacity cut problem in a related network and propose an optimum multiuser detection algorithm with polynomial computational complexity for a certain class of signature sequences. The minimum cut problem is solvable in polynomial time if the capacities of the links not incident to source and sink are nonnegative. This condition in the optimum detection problem is equivalent to all cross correlations between the signature sequences of the users being negative. One example of such a set of signature sequences is obtained when shifted versions of the maximal length sequences (or m-sequences) are used. In this case the cross correlation between users i and j is given as /spl Gamma//sub ij/=-1/G for all i,j, where G is the processing gain.read more
Citations
More filters
Journal ArticleDOI
Quantum signal processing
TL;DR: This framework provides a unifying conceptual structure for a variety of traditional processing techniques and a precise mathematical setting for developing generalizations and extensions of algorithms, leading to a potentially useful paradigm for signal processing with applications in areas including frame theory, quantization and sampling methods, detection, parameter estimation, covariance shaping, and multiuser wireless communication systems.
Journal ArticleDOI
Decision feedback multiuser detection: a systematic approach
TL;DR: A systematic approach to decision feedback multiuser detection is introduced for the joint detection of symbols of K simultaneously transmitting users of a synchronous correlated waveform multiple-access (CWMA) channel with Gaussian noise.
Journal ArticleDOI
The application of semidefinite programming for detection in CDMA
Peng Hui Tan,Lars K. Rasmussen +1 more
TL;DR: A detection strategy based on a semidefinite relaxation of the CDMA maximum-likelihood (ML) problem is investigated and it is demonstrated that this approach provides a good approximation to the ML performance.
Journal ArticleDOI
CDMA multiuser detection: a nonlinear programming approach
TL;DR: This work takes the approach of approximating the solution of the optimum multiuser detection problem (OMUD) using nonlinear programming relaxations and identifies the convergence properties of iterative detectors which correspond to previously proposed heuristic nonlinear detectors.
Journal ArticleDOI
Constrained maximum-likelihood detection in CDMA
TL;DR: A close relationship between a sphere-constrained ML detector and the well-known minimum mean square error detector is found and verified, and an iterative algorithm for solving a CCS constraint problem is derived based on results in linear variational inequality theory.
References
More filters
Book
Network Flows: Theory, Algorithms, and Applications
TL;DR: In-depth, self-contained treatments of shortest path, maximum flow, and minimum cost flow problems, including descriptions of polynomial-time algorithms for these core models are presented.
Book
Network Flows
TL;DR: The question the authors are trying to ask is: how many units of water can they send from the source to the sink per unit of time?
Journal ArticleDOI
Minimum probability of error for asynchronous Gaussian multiple-access channels
TL;DR: The results show that the proposed multiuser detectors afford important performance gains over conventional single-user systems, in which the signal constellation carries the entire burden of complexity required to achieve a given performance level.
Journal ArticleDOI
Computational complexity of optimum multiuser detection
TL;DR: It is shown that the combinatorial problem of selecting the most likely transmitted data stream given the sufficient statistics, and the signal energies and cross-correlations is nondeterministic polynomial-time hard (NP-hard) in the number of users.
Journal ArticleDOI
Minimum cuts and related problems
Jean-Claude Picard,H. D. Ratliff +1 more
TL;DR: This characterization of a cut in a network provides a fundamental equivalence between directed pseudosummetric networks and undirected networks and identifies a class of problems which can be solved as minimum cut problems on a network.