Performance of multi-stage canceller for narrowband interference rejection in DS-CDMA system

In order to improve spectral efficiency, CDMA overlay, which means co-existence of wideband and narrowband signals in the same frequency band, has been considered. However, signals from existing narrowband system are not necessarily transmitted with low enough power level not to give damage to DS-CDMA (direct sequence code division multiple access) signals, so an efficient rejection technique for narrowband interferers is required for successful CDMA overlay. Furthermore, it is necessary to cope with sudden changes of interference power levels associated with their appearance/disappearance. In this paper, we propose a canceller to reject such high power narrowband interference for the DS-CDMA system and show the rejection performance obtained from the computer simulation