Quasi-Synchronous Multi-Carrier Time Division Duplex DS-CDMA in Reverse Link over Multipath Fading Channel

摘要

A quasi-synchronous (QS) Multi-Carrier time division duplex US-CDMA is studied for reverse link on multi-path indoor environment. Quasi-synchronous DS-CDMA drastically reduces the effect of multiple access interference with several interesting features of time division duplex (TDD) mode for mobile communications. In this paper, we use the time division duplex transmission mode and each user appropriately adjusts its transmission time, through feed back control from the base station, so its signal can arrive at the base station synchronously with the other mobile stations. This paper evaluates the performance of a quasi-synchronous multi-carrier TDD DS-CDMA for reverse link on multipath indoor environment. The performance results are shown with different quasi-synchronous accuracy and power control error values. Orthogonal codes are used for spreading the signals in QS transmission. On the other hand, random codes arc used for an asynchronous transmission. From the results, when the performance of asynchronous system is assumed to be a reference, we can see that the Constraint of quasi-synchronous accuracy equals 2.3 chips of multi-carrier system at spreading factor 32.