Narrowband Interference Suppression for PN Code Acquisition in a DS/CDMA Overlay Environment

Jin Young KIM  

IEICE TRANSACTIONS on Communications   Vol.E83-B   No.8   pp.1631-1639
Publication Date: 2000/08/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Personal, Indoor and Mobile Radio Communications)
narrowband interference,  PN code,  acquisition,  DS/CDMA overlay,  

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In this paper, performance of a PN code acquisition scheme is analyzed and simulated for a DS/CDMA overlay system where a CDMA user and a narrowband user coexist in the same frequency band. A narrowband user is modelled as a narrowband interference (NBI) located at the fraction of a CDMA user's bandwidth. To suppress the NBI, an interference suppression filter is employed at the receiver frontend. Acquisition performance is evaluated in terms of mean acquisition time using state transition diagram for acquisition process. To apply for a DS/CDMA mobile cellular environments, multiple access interference and imperfection of power control are taken into account in the analysis of acquisition performance. The imperfect power control is considered by modelling the power of each user to be lognormally distributed about nominal received power. From the simulation results, it is shown that for the cases of perfect and imperfect power control, the interference suppression filter is very effective for supprssion of the NBI and rapid PN code acquisition in a DS/CDMA overlay environment. It is also shown that the one-sided tap number of 5 for interference suppression filter is sufficient to suppress the NBI. And, capacity estimates are compared based on acquisition and BER performance. The analysis in this paper can be applied to the practical situations for a DS/CDMA overlay environment.