Oversampling in a forced-asynchronous CDMA system

We demonstrate the performance gains attainable through the aid of oversampling in an asynchronous direct sequence code division multiple access (CDMA) system. In chip-rate sampled systems with spreading factor N´, the dimensionality of the system is N, limiting the number of supportable users. We show that oversampling increases the dimensions beyond this factor. The increased dimensionality allows the support of more users or a higher separation between existing users. We formulate an optimization problem over user delays and spreading codes that achieves maximum system performance. This forced-asynchronous CDMA system creates a novel area of optimization with immediate implications on code and system design