Title :
Adaptive multi-user equalizer using multi-dimensional lattice filters for DS-CDMA
Author :
Jitsukawa, Daisuke ; Kohno, Ryuji
Author_Institution :
Div. of Electr. & Comput. Eng., Yokohama Nat. Univ., Japan
Abstract :
This paper proposes and investigates the adaptive multi-user equalizer based on the multi-dimensional IIR lattice filter in order to suppress the co-channel interference (CCI) in an asynchronous DS/CDMA system. An asynchronous DS/CDMA system with a multi-user receiver is modeled as a multi-dimensional or multi-input/out system with cross-coupling that is co-channel interference. From the system model it is shown that the multi-user detection is reduced to a problem of multi-dimensional equalization for multiaccess interference as well as intersymbol interference. The proposed multi-user equalizer can improve the equalizing error of the filter, compared with that of the multidimensional FIR transversal filter of which the number of taps is finite. The multi-dimensional lattice filter can adaptively achieve fast and stable convergence with less taps. Since the filter can resolve a correlative multiple input into an orthogonal output stage by stage, the CCI can be removed. Computer simulations show the performance of the proposed scheme
Keywords :
IIR filters; adaptive equalisers; cellular radio; cochannel interference; code division multiple access; convergence of numerical methods; filtering theory; interference suppression; intersymbol interference; land mobile radio; lattice filters; multidimensional digital filters; pseudonoise codes; radiofrequency interference; spread spectrum communication; DS-CDMA cellular system; adaptive multiuser equalizer; asynchronous DS/CDMA system; cochannel interference suppression; computer simulations; convergence; correlative multiple input; intersymbol interference; multiaccess interference; multidimensional IIR lattice filter; multidimensional equalization; multidimensional lattice filters; multiinput/out system; multiuser receiver; orthogonal output; performance; system model; Adaptive filters; Equalizers; Finite impulse response filter; IIR filters; Interchannel interference; Intersymbol interference; Lattices; Multiaccess communication; Radiofrequency interference; Transversal filters;
Conference_Titel :
Spread Spectrum Techniques and Applications Proceedings, 1996., IEEE 4th International Symposium on
Conference_Location :
Mainz
Print_ISBN :
0-7803-3567-8
DOI :
10.1109/ISSSTA.1996.563184