Essential Guide to Telecommunications, The, Third Edition

Time Division Multiple Access, GSM and Code Division Multiple Access Air Interfaces

All digital wireless services use multiplexing techniques to carry more calls on the same amount of spectrum as analog cellular service. Multiplexers are devices that transmit signals from two or more devices over a single channel. Thus, while all digital services have more capacity than analog cellular, the ways they add capacity are incompatible with each other. That is why callers cannot necessarily use their cellular telephones when they travel. The three most prevalent multiplexing techniques in the world are time division multiple access (TDMA), code division multiple access (CDMA) and Global System for Mobile Communications (GSM). When used in wireless ...