library.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Analog Wireless Telephony (AMPS) Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: CDMA CAPACITY AND QUALITY OPTIMIZATION Chapter TDMA Wireless Telephony (GSM) With effective cellular engineering already developed in Advanced Mobile Phone Ser- vice (AMPS), the designers of the Global System for Mobility (GSM) could focus on the next major step in the evolution of cellular. That step was the application of digital technology to voice telephony. The technology they chose was time division multiple ac- cess (TDMA), where each digitized voice signal is sent in a particular, periodic time slot measured in milliseconds. GSM was developed as a pan-European standard with the hope that it would become a world standard. GSM is actually not a single standard but rather a set of standards specifying many differing interfaces. This allows different manufacturers in different nations to develop components of the GSM system. When the components are brought together on a single network, they are likely to work well together, although, of course, they should be tested thoroughly. The Europeans used an international standard to ful- fill the same function that corporate consortiums often fulfill in the United States. 7.1 GSM Architecture GSM is laid out somewhat differently from AMPS. Where AMPS has a controller in each base station, GSM concentrates the cell controller function in a single base station controller (BSC) for several cells. GSM refers to the controller-less base station as a base transceiver station (BTS). The entire network of base stations for one BSC is called a base station system (BSS). One mobile switching center (MSC) can control several BSCs. We can think of the BSC as another level in the G