Quasi-coherent delay-locked loops for fading channels

Author

Latva-aho, Matti ; Vallström, Jari

Author_Institution

Telecommun. Lab., Oulu Univ., Finland

Volume

1

fYear

1996

fDate

22-25 Sep 1996

Firstpage

455

Abstract

The most widely used delay estimators in DS-CDMA receivers are based on the delay-locked loops (DLL). In a coherent RAKE receiver the complex channel coefficient estimate can be used to attain the phase coherency in DLL and the effect of data modulation can be removed via decision feedback. The resulting algorithms are called quasi-coherent delay-locked loops (QCDLL). The performance of four variations for QCDLLs based on lead-lag phase-locked loops has been analyzed by computer simulations. All the loops performed satisfactorily in a fading channel, but the quasi-coherent sample-correlate-choose-largest (QCSCCL) loop had 5-6 dB better performance than the other schemes

Keywords

adaptive control; circuit feedback; correlation methods; delay circuits; fading; pseudonoise codes; radio receivers; signal sampling; spread spectrum communication; telecommunication control; DLL; adaptive loop gain control algorithms; coherent RAKE receiver; complex channel coefficient estimate; computer simulations; data modulation; decision feedback; fading channel; fading channels; lead-lag phase-locked loops; performance; phase coherency; quasicoherent delay-locked loops; quasicoherent sample-correlate-choose-largest loop; Delay estimation; Fading; Feedback; Multiaccess communication; Multipath channels; Performance analysis; Phase estimation; Phase locked loops; Phase modulation; RAKE receivers;

fLanguage

English

Publisher

ieee

Conference_Titel

Spread Spectrum Techniques and Applications Proceedings, 1996., IEEE 4th International Symposium on

Conference_Location

Mainz

Print_ISBN

0-7803-3567-8

Type

conf

DOI

10.1109/ISSSTA.1996.563818

Filename

563818