High power narrowband interference rejection technique based on multi-stage canceller for DS-CDMA system

It is difficult to assign independent radio frequency bands to wideband DS-CDMA (direct sequence code division multiple access) systems because of lack of radio frequency resources, so that CDMA overlay technique, which means co-existence of wideband and narrowband signals in the same frequency band, has been considered to improve spectral efficiency. In the overlay situation, however, signals from existing narrowband systems are not necessarily transmitted with low power level enough not to give damage to DS-CDMA signals, so that an efficient rejection technique for high power narrowband interferers is required for successful CDMA overlay. We propose a high power narrowband interference rejection method which connects several narrowband interference cancellers with simple construction in series and show its rejection performance obtained from computer simulation