We apply belief propagation (BP) to multi--user detection in a spread spectrum system, under the assumption of Gaussian symbols. We prove that BP is both convergent and allows to estimate the correct conditional expectation of the input symbols. It is therefore an optimal --minimum mean square error-- detection algorithm. This suggests the possibility of designing BP detection algorithms for more general systems. As a byproduct we rederive the Tse-Hanly formula for minimum mean square error without any recourse to random matrix theory.
@article{arxiv.cs/0510044,
title = {Belief Propagation Based Multi--User Detection},
author = {Andrea Montanari and Balaji Prabhakar and David Tse},
journal= {arXiv preprint arXiv:cs/0510044},
year = {2007}
}
Comments
9 pages, 4 eps figures. Forty-third Allerton Conference on Communications, Control and Computing, invited paper