The world has seen phenomenal growth in deployment of wireless cell site equipment, with close to 200,000 wireless base stations by the end of 1998, according to estimate, and over 60,000 in the United States alone. Forecasts are that phenomenal growth will continue for at least a few more years, with the total number more than doubling by the year 2001.
Synchronization is essential to the effective operation of telecommunications networks.
As with any other network element, they need synchronization to ensure voice and data communications are transported undisturbed by transmission impairments such as jitter and wander. Transport synchronization requirements are specified in ANSI T1.101, with DS1 mask conformance required for network end nodes such as cell sites. CDMA also requires a precise time reference, while GSM and TDMA don't. Additionally, since synchronization devices are used to manage the pilot frequencies of the mobile radio interface, low phase noise requirements are needed for spectral purity. In meeting this requirement, the industry has standardized on the deployment of GPS timing receivers in all base stations.