A novel blind code synchronization scheme for DS-CDMA systems in multipath fading channels

We present a blind code synchronization scheme, referred to as the Capon algorithm, for DS (direct sequence) CDMA (code division multiple access) systems. The only required knowledge of the proposed scheme is the spreading code of the desired user, so that it is appealing for a decentralized implementation. The Capon algorithm can be used in frequency-flat or frequency-selective, time-invariant or time-varying fading channels; it is able to deal with colored channel noise and unknown interference of various origins, such as inter-cell interference and interference in cellular overlay systems. The Capon algorithm can be readily implemented using standard adaptive schemes, making it amenable to not only acquisition but tracking as well. An additional advantage enjoyed by Capon is that it does not need to know the number of active transmissions, a knowledge usually indispensable for some blind algorithms to function properly. Numerical simulations are presented to illustrate the performance of the proposed Capon scheme.