Title :
Joint synchronization and symbol detection in asynchronous DS-CDMA systems
Author :
Rey, Francesc ; Vázquez, Gregori ; Riba, Jaume
Author_Institution :
Dept. de Teoria del Senyal i Comunicacions, Univ. Politecnica de Catalunya, Barcelona, Spain
Abstract :
The design of accurate estimators which also consider the noise term in low SNR scenarios is paramount for achieving optimal solutions and obtaining precise symbol detectors. Particularly, this paper estimates the propagation delays focusing on asynchronous DS-CDMA systems. The proposed minimum conditioned variance (MCV) is the choice in noisy environments, implementing the best linear detector of the transmitted symbols under a minimum mean-square error criterion. The result is an estimator that improves the conditional ML (CML) solution when noise is not negligible, and attains the derived Gaussian unconditional Cramer-Rao bound (UCRB) in the whole EbNo range as classical Gaussian unconditional ML (UML) does. Consequently, the proposed MCV estimator, becomes an optimal quadratic solution achieving similar features than UML in a straightforward way, and with no assumptions on the signal statistics
Keywords :
Gaussian distribution; code division multiple access; delay estimation; least mean squares methods; minimisation; signal detection; spread spectrum communication; synchronisation; Gaussian unconditional Cramer-Rao bound; SNR; asynchronous DS-CDMA; linear detector; minimum conditioned variance; minimum mean-square error; optimal quadratic solution; propagation delays; signal statistics; symbol detection; symbol detectors; synchronization; Delay estimation; Detectors; Gaussian noise; Maximum likelihood estimation; Multiaccess communication; Propagation delay; Signal to noise ratio; Statistics; Unified modeling language; Working environment noise;
Conference_Titel :
Statistical Signal and Array Processing, 2000. Proceedings of the Tenth IEEE Workshop on
Conference_Location :
Pocono Manor, PA
Print_ISBN :
0-7803-5988-7
DOI :
10.1109/SSAP.2000.870214
