se Station Controller (BSC) is the traffic cop of the mobile network. It per- forms the precall setup, which means that it assigns calls to radio channels in the BTS, sends ringing to the correct channel, and measures signal strength. In digital 2G and 3G cellular service, one controller can manage many BTSs. Third-Generation Digital Mobile Air Interfaces The main drivers behind third-generation (3G) mobile networks were a need for more capacity and the capability for operators to offer revenue-producing services that require advanced 3G networks. The International Telecommunications Union (ITU) started an effort called IMT- 2000 (international mobile telephone) to define one advanced digital standard for next- generation voice and high-speed data on cellular networks. Unfortunately, the ITU subcommittees endorsed several 3G techniques due to political pressure from opera- tors and manufacturers who wanted standards to more closely match the equipment they produced and used in their networks. 3G standards have various evolutions, referred to as releases or revisions, which improve upon and increase speeds, capacity, and suitability for converged networks capable of carrying voice, video, and data. Voice is transmitted by using circuit switch- ing, which is less efficient than Voice over Internet Protocol (VoIP). The peak and Second-, Third-, and Fourth-Generation Digital Networks attainable data rates associated with these services vary because of a number of factors, including distance from antennas, congestion within the cell, and weather conditions. The Most Common 3G Technologies As previously indicated, 3G standards are collectively known as IMT-2000. The most widely implemented 3G standards are WCDMA and CDMA2000. Although the first CDMA2000 3G networks were installed in 2000 and the first WCDMA network was installed in 2001, many carriers worldwide are still in the process of adding 3G proto- cols to their networks. The following is a list of 3G technologies. Wideband CDMA (WCDMA) This is the 3G standard t