A NOISE WHITENING APPROACH TO MULTIPLE-ACCESS NOISE REJECTION .2. IMPLEMENTATION ISSUES

Several practical methods are proposed for the implementation of linea r filters that reject multiple-access noise in direct sequence code-di vision multiple-access (DS-CDMA) receivers. These methods rely on taki ng advantage of variations in the received chip spectrum, and do not r equire locking and despreading multiple signals. The resulting structu res are simple, and some can operate at a high chip rate. Adaptive str uctures are also proposed. It is shown that a close relationship exist s between noise whitening and chip-equalization for a DS-CDMA receiver . System issues affecting the choice of the chip spectrum, and thus th e applicability of these methods, are described.