Multi-user detection of nonlinearly distorted MC-CDMA symbols by microstatistic filtering

Jozef Krajňák, Marc Deumal, Pavol Pavelka, Dušan Kocur, Joan Lluís Pijoan, Pavol Galajda

Research output: Indexed journal article Articlepeer-review

13 Citations (Scopus)

Abstract

Multi-carrier code division multiple access is a powerful modulation technique that is being considered in many emerging broadband communication systems. In a downlink scenario orthogonal spreading sequences are used since they reduce multiple access interference compared to non-orthogonal. However, the nonlinear amplification of the transmitted signal destroys the orthogonality and, thus, reduces the system performance. In order to avoid performance degradation without requiring large back-offs in the transmitter amplifier, it becomes necessary to use multi-user detection techniques at the receiver side. Conventional multi-user detectors (MUD) are designed for linear environments and, as a result, might not exhibit enough performance improvement. In this paper a new MUD based on microstatistic filtering is proposed. The presented MUD uses piece-wise linear filtering in conjunction with threshold decomposition of the input signal, which introduces a nonlinear effect, to improve performance when a nonlinearity is present. Maximum performance improvement compared to conventional MUD is achieved for low spreading factors and user loads no greater than 50%.

Original languageEnglish
Pages (from-to)149-160
Number of pages12
JournalWireless Personal Communications
Volume47
Issue number1
DOIs
Publication statusPublished - Oct 2008

Keywords

  • MC-CDMA
  • Microstatistic filter
  • Multi-user detection
  • Nonlinear distortion

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