Blind multiuser receivers for code-hopping DS-CDMA systems

Blind detection of a desired user´s signal in a code-hopping (CH) direct sequence code division multiple access (DS-CDMA) system is considered. In CH CDMA systems each user switches between a predetermined set of (short-)code sequences. A user signal in such systems may be treated as the superposition of several virtual short-code signals. A code-constrained inverse filter criterion (IFC)-based blind detector for short-code CDMA signals to detect a desired user´s signal was recently presented by Tugnait and Li (2001). In this paper a novel approach combining the code-constrained IFC and a penalty function is proposed to simultaneously extract all virtual users associated with a given CH user. Global minima of the proposed cost function are analyzed. An illustrative simulation example is provided.