Parameter estimation of DS-CDMA mobile communication

Abstract

The parameter estimation is a very important issue in DS-CDMA mobile communication. Since all users share the same frequency and time resource during communications, the multiple-access interference (MAI) must be considered with great care. It may be due to that the users' signals are not truly orthogonal after spreading. When the communication is in a near-far environment, the users' power levels may vary widely. This would result in the performance degradation of the conventional CDMA system. In order to overcome this problem, several near-far resistant detectors were reported. And these methods require the signature waveforms' timing information. However, for the asynchronous CDMA systems, even in a friendly communication scheme, the users' timing information is often not known and need to be estimated.