Adaptive Lattice Step-Size Algorithm for Narrowband Interference Suppression in DS/CDMA Systems

  • Benjangkaprasert, Chawalit (Research Center for Communications and Information Technology (ReCCIT), and Department of Information Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang) ;
  • Teerasakworakun, Sirirat (Research Center for Communications and Information Technology (ReCCIT), and Department of Information Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang) ;
  • Jorphochaudom, Sarinporn (Research Center for Communications and Information Technology (ReCCIT), and Department of Information Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang) ;
  • Janchitrapongvej, Kanok (Research Center for Communications and Information Technology (ReCCIT), and Department of Information Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang)
  • Published : 2003.10.22

Abstract

The presence of narrowband interference (NBI) in Direct-sequence code division multiple access (DS/CDMA) systems is an inevitable problem when the interference is strong enough. The improvement in the system performance employs by adaptive narrowband interference suppression techniques. Basically there have been two types of method for narrowband interference suppression estimator/subtracter approaches and transform domain approaches. In this paper the focus is on the type of estimator/subtracter approaches. However, the binary direct sequence (DS) signal, that acts as noise in the prediction process is highly non-Gaussian. The case of a Gaussian interferer with known in an autoregressive (AR) signal or a digital signal and also in a sinusoidal signal (Tone) that included in is paper. The proposed NBI suppression is presence in an adaptive IIR notch filter for lattice structure and more powerful by using a variable step-size algorithm. The simulation results show that the proposed algorithm can significantly increase the convergence rate and improved system performance when compare with adaptive least mean square algorithm (LMS).

Keywords