Robust GPS-Based Synchronization of CDMA Mobile Networks

摘要

Mobile communication networks based on the cdmaOne and cdma2000 standards require that the base-stations of their radio access networks be synchronized. All the base-stations of the network need a 1PPS phase reference with an accuracy of 3 microsecs. The Global Positioning System (GPS) is currently the only practical way of implementing this type of synchronization. This paper proposes a two-fold protection concept for the base-station's phase clock. In case of a GPS-reception problem, the phase reference signal is maintained using the auxiliary frequency reference signal taken from the SONET (Synchronous Optical Network) transport network. When the latter fails (double failure), the clock eventually enters holdover mode. The paper analyzes the performance of the two protection modes, and compares it to the requirements of CDMA-based mobile networks.