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Performance analysis of adaptive receivers for DS/CDMA communication systems
Author(s) -
Ueng FangBiau,
Chen JunDa,
Yang JiaYu
Publication year - 2008
Publication title -
international journal of communication systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.344
H-Index - 49
eISSN - 1099-1131
pISSN - 1074-5351
DOI - 10.1002/dac.950
Subject(s) - computer science , infinite impulse response , code division multiple access , least mean squares filter , finite impulse response , intersymbol interference , algorithm , minimum mean square error , interference (communication) , bit error rate , channel (broadcasting) , adaptive filter , digital filter , telecommunications , mathematics , bandwidth (computing) , statistics , decoding methods , estimator
Both intersymbol interference (ISI) and multiple‐access interference (MAI) are the important issues in code division multiple access (CDMA) multiuser communication systems. The step size of the traditional least‐mean‐square (LMS) adaptive receivers must be substantially adjusted to overcome the effect due to different channel responses or different numbers of active users. The normalized‐LMS (NLMS) algorithm can automatically manipulate the adjustment to avoid the problem just discussed. This paper proposes the symbol‐based interference rejection filter with NLMS algorithm and derives both finite impulse response (FIR)‐ and infinite impulse response (IIR)‐type algorithms. We also derive the optimal step sizes and minimum mean‐square errors (MSEs) for both the FIR and IIR symbol‐based receivers. The complexity of our proposed FIR receiver is lower than that of the conventional chip‐based receivers. In addition, it is shown that the bit error rate performance of our proposed symbol‐based receivers is superior to conventional one in the simulations. Simulations also show the correctness of our theoretical analysis of minimum MSE. Copyright © 2008 John Wiley & Sons, Ltd.