Title :
Blind chip-rate equalisation for DS-CDMA downlink receiver
Author :
Weiss, S. ; Hadef, M. ; Konrad, M. ; Rupp, M.
Author_Institution :
Sch. of Electron. & Comput. Sci., Southampton Univ., UK
Abstract :
A dispersive channel in the DS-CDMA downlink destroys the orthogonality of the synchronous users´ spreading sequences. In this paper, we aim to reestablish this orthogonality blindly by means of a common chip-level equaliser. The adaptation algorithm is based on a constant modulus criterion forcing the various user symbols onto a constant modulus, for which a stochastic gradient descent algorithm is derived. This algorithm is structurally similar to a multiple error filtered-X LMS type approach, whereby the equaliser input CM update is replaced by a spreading code filtered version. Various simulations demonstrating the algorithm´s convergence and noise performance are presented.
Keywords :
adaptive filters; blind equalisers; code division multiple access; dispersive channels; gradient methods; radio receivers; spread spectrum communication; stochastic processes; DS-CDMA downlink receiver; adaptation algorithm; blind chip-rate equalisation; chip-level equaliser; constant modulus criterion; convergence; dispersive channel; noise performance; spreading code filtered version; stochastic gradient descent algorithm; synchronous user spreading sequence; Blind equalizers; Cost function; Decoding; Dispersion; Downlink; Error correction; Error correction codes; Least squares approximation; Multiaccess communication; Multiple access interference;
Conference_Titel :
Signals, Systems and Computers, 2004. Conference Record of the Thirty-Seventh Asilomar Conference on
Conference_Location :
Pacific Grove, CA, USA
Print_ISBN :
0-7803-8104-1
DOI :
10.1109/ACSSC.2003.1292195
