Robust Channel Estimation and Multiuser Detection for MC---CDMA Systems Under Narrowband Interference

  • Authors:
  • H. Cheng;S. C. Chan;Z. G. Zhang

  • Affiliations:
  • Electrical and Electronic Engineering Department, University of Hong Kong, Hong Kong, Hong Kong;Electrical and Electronic Engineering Department, University of Hong Kong, Hong Kong, Hong Kong;Electrical and Electronic Engineering Department, University of Hong Kong, Hong Kong, Hong Kong

  • Venue:
  • Journal of Signal Processing Systems
  • Year:
  • 2008

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Abstract

In this paper, we present a robust adaptive channel estimator and a robust multiuser detector for wireless multicarrier code-division multiple access (MC---CDMA) systems under narrowband interference (NBI). The conventional least-squares (LS) channel estimator performs poorly when narrowband interfering signals contaminate the multicarrier systems. A new weighted recursive least M-estimate (WRLM) channel estimator is hence developed to estimate multipath fading channels in the presence of NBI. The new robust channel estimator resorts to M-estimate and weighted least-squares (WLS) techniques. Simulations show that the WRLM channel estimator offers substantial performance gain over conventional recursive least-squares (RLS), recursive least M-estimate (RLM) and weighted RLS (WRLS) channel estimators under NBI. With the estimated channel coefficients, a robust multiuser detector is proposed to jointly suppress multiple access interference (MAI) and NBI. The performance of the linear decorrelator will degrade substantially in the presence of NBI. A weighted least M-estimate (WLM) algorithm is therefore developed to combat the NBI. The WLM multiuser detector is also based on the weighted M-estimate concept. Numerical results show that the proposed WLM multiuser detector significantly outperforms over the conventional linear decorrelator, the robust decorrelator with M-estimate and the WLS detector under NBI.