Adaptive interference suppression in CDMA systems by LCL-PTV filtering

This paper deals with narrowband interference suppression in direct-sequence code-division multiple-access (CDMA) systems. In order to take advantage of the cyclostationary nature of the interfering signal, we propose here to adopt a linear conjugate-linear (LCL) polyperiodically time-varying (PTV) filter in the suppression stage, whose adaptive implementation is based on the RLS algorithm. Unlike the conventional linear time-invariant filter, the LCL-PTV structure exploits also the spectral correlation properties of the interference, achieving therefore a better suppression performance. The numerical results confirm the superiority of the proposed LCL-PTV scheme with respect to the conventional one, especially when operating in the presence of strong interfering signals.