Performance analysis of linear multiuser detectors for randomly spread CDMA using Gaussian approximation

Document Type

Article

Publication Date

2-1-2002

Abstract

In this paper, the performance of a linear decorrelating detector (LDD) and a minimum mean square error (MMSE) detector will be analyzed for random spreading waveforms. The performance of the LDD and MMSE detectors is expressed in terms of the so-called near-far resistance, defined by a reciprocal of a diagonal component of inverse matrix. For random code division multiple access, which employs random spreading waveforms, the near-far resistance can be regarded as a random variable. Recently, many papers have dealt with the analysis of multiuser detectors for random spreading sequences. In most cases, however, these analyses derived only the expectations or bounds for the near-far resistance. In this paper, we will directly derive the approximate probability density function (PDF) of the near-far resistance and corresponding bit error rate expression for random spreading sequences. It is based on Gaussian approximation of cross correlation between any two randomly generated spreading codes. The resulting PDF turned out to be a reversed-and-scaled version of chi-square distribution. The approximate expressions, both the PDF and the corresponding bit error rate expression, will be verified via Monte Carlo simulations. The results showed that the approximation is quite close to the simulation results when the number of users is less than half the processing gain.

Identifier

0036474881 (Scopus)

Publication Title

IEEE Journal on Selected Areas in Communications

External Full Text Location

https://doi.org/10.1109/49.983364

ISSN

07338716

First Page

409

Last Page

418

Issue

2

Volume

20

Grant

CCR-0085846

Fund Ref

National Science Foundation

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