Output MAI distributions of linear MMSE multiuser receivers in DS-CDMA systems

Junshan Zhang, E. K P Chong, D. N C Tse

Research output: Contribution to journalArticle

151 Citations (Scopus)

Abstract

Multiple-access interference (MAI) in a code-division multiple-access (CDMA) system plays an important role in performance analysis and characterization of fundamental system limits. In this paper, we study the behavior of the output MAI of the minimum mean-square error (MMSE) receiver employed in the up-link of a direct-sequence (DS)-CDMA system. We focus on imperfect power-controlled systems with random spreading, and establish that in a synchronous system 1) the output MAI of the MMSE receiver is asymptotically Gaussian, and 2) for almost every realization of the signatures and received powers, the conditional distribution of the output MAI converges weakly to the same Gaussian distribution as in the unconditional case. We also extend our study to asynchronous systems and establish the Gaussian nature of the output interference. These results indicate that in a large system the output interference is approximately Gaussian, and the performance of the MMSE receiver is robust to the randomness of the signatures and received powers. The Gaussianity justifies the use of single-user Gaussian codes for CDMA systems with linear MMSE receivers, and implies that from the viewpoints of detection and channel capacity, signal-to-interference ratio (SIR) is the key parameter that governs the performance of the MMSE receiver in a CDMA system.

Original languageEnglish (US)
Pages (from-to)1128-1144
Number of pages17
JournalIEEE Transactions on Information Theory
Volume47
Issue number3
DOIs
StatePublished - Mar 2001

Fingerprint

Multiple access interference
Mean square error
Code division multiple access
interference
recipient
Channel capacity
Gaussian distribution
performance

Keywords

  • Central limit theorem
  • Martingale difference array
  • Minimum mean-square error (MMSE) receiver
  • Multiple-access interference (MAI)
  • Power control
  • Random signature

ASJC Scopus subject areas

  • Information Systems
  • Electrical and Electronic Engineering

Cite this

Output MAI distributions of linear MMSE multiuser receivers in DS-CDMA systems. / Zhang, Junshan; Chong, E. K P; Tse, D. N C.

In: IEEE Transactions on Information Theory, Vol. 47, No. 3, 03.2001, p. 1128-1144.

Research output: Contribution to journalArticle

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