DocumentCode :
1062378
Title :
All-Pass Prefiltering in Pre-Post-Rake Schemes for Spread-Spectrum Communications
Author :
Giunta, Gaetano ; Vandendorpe, L. ; Benedetto, F.
Author_Institution :
Univ. of Roma Tre, Rome
Volume :
55
Issue :
8
fYear :
2007
Firstpage :
4330
Lastpage :
4334
Abstract :
Pre-Post-Rake is a known technique in spread-spectrum communications that uses one rake filter at the transmitter side (to partially precompensate for the wireless channel dispersion) and one rake filter at the receiver side (matched to the entire transmitter plus channel chain). A novel scheme based on transmitter all-pass filtering has been employed by the authors to enhance the performance in the downlink of direct sequence code division multiple access (DS/CDMA) system. In this correspondence, we explain by theoretical analysis why the structure performs well. In particular, we show that the interference can be reduced by all-pass prefiltering. In fact, it basically acts as a (phase-only) preequalizer of the multipath channel that combats intersymbol interference. On the other hand, it better preserves the orthogonality between near orthogonal pseudorandom codes in multiuser synchronous DS/CDMA environments. The performance is analyzed for wireless multipath channels, simulated by realistic models, to evidence its gain (in terms of dispersion index) compared to conventional pre-post-rake.
Keywords :
all-pass filters; code division multiple access; multipath channels; radio receivers; spread spectrum communication; all-pass prefiltering; direct sequence code division multiple access system; downlink; interference reduction; intersymbol interference; multiuser synchronous DS/CDMA environment; orthogonal pseudorandom code; performance analysis; pre-post-rake scheme; rake filter; spread-spectrum communication; transmitter all-pass filtering; wireless multipath channel; Direct-sequence code-division multiple access; Downlink; Filtering; Matched filters; Multiaccess communication; Multipath channels; Performance analysis; RAKE receivers; Spread spectrum communication; Transmitters; All-pass digital filters; rake receivers; signal processing algorithms for mobile communications; spread-spectrum communications;
fLanguage :
English
Journal_Title :
Signal Processing, IEEE Transactions on
Publisher :
ieee
ISSN :
1053-587X
Type :
jour
DOI :
10.1109/TSP.2007.896089
Filename :
4276972
Link To Document :
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