Single-User Receiver Based on Orthogonalizing Matched Filter Using Multi-Dimensional Lattice Filters for DS/CDMA

Daisuke JITSUKAWA  Ryuji KOHNO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.8   pp.1566-1574
Publication Date: 1999/08/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Digital Signal Processing)
DS/CDMA,  co-channel interference,  orthogonalizing matched filter,  lattice filter,  

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This paper proposes and investigates the adaptive single-user receiver with co-channel interference (CCI) canceller based on orthogonalizing matched filter (OMF) using the multi-dimensional (multi-D) lattice filters for DS/CDMA in a multipath environment. A conventional single-user receiver using OMF cannot correctly cancel CCI in the presence of multipath in a channel, because the desired user's signal component and other users' intersymbol interference (ISI), due to multipath, still remain at the output of OMF, and then a correct replica of CCI cannot be generated. The proposed receiver can solve this problem because a multi-D IIR lattice filter can distinguish the desired user's signal component from the other users' ones and remove the ISI of all users' signals by Gram-Schmidt orthogonalization. And a multi-D FIR lattice filter can selectively regenerate undesired users' signal components which contain neither the desired user's signal component nor ISI. The proposed receiver based on multi-D lattice filters can apply orthogonality property of the OMF to not only a direct wave but also to delayed waves in a multipath channel. Since the proposed receiver does not have to know spreading codes of multiusers except the desired user, it will be applicable at a mobile terminal in the forward link in a multipath environment. Computer simulations show the proposed receiver have capability to cancel the CCI and converges fast in a multipath channel.