Reverse link pilot-tones aided synchronization in DS-CDMA communication system

Due to the limitation of conventional communication theory, IS-95 type CDMA cellular systems can only use pilot signals in the forward link to yield coherent detection. In the reverse link non-coherent detection is applied without pilot signals. In this paper, the reverse link pilot-tones aided synchronization which utilizes the aided pilots to facilitate the timing and carrier recovery (with linear complexity to the number of users) is proposed based on the development of multiuser synchronization. In the meanwhile, with proper separation of these transmitted aided pilot tones over frequency and/or time domain controlled by the base station, it is easy to identify these pilots. With more practical considerations, the proposed pilot-tones aided synchronization still works when the other mobile handsets transmit their packets simultaneously. The enhanced-performance linear minimum mean square error detector which considers the aided pilots and outperforms the linear minimum mean square error detector is proposed and analytically shown to provide better performance. In the simulations, the huge performance gain clearly illustrates potential applications in future CDMA wireless systems.