Wireless Primer-2G Technology

The dominant wireless-networking technology during the past few years has
been 2G technology, which is digital, circuit-based, and narrowband but suitable for voice and limited data communications.
Time-division multiple-access technology, used primarily in the US, increases bandwidth by dividing each cellular channel into three time slots (a technique known as time-division multiplexing), each of which handles a separate transmission. The channel then switches quickly from slot to slot, thereby handling three communications simultaneously.
Global System for Mobile Communications—the world’s most popular 2G technology, implemented in much of Europe and Asia—is also based on time-division multiplexing but uses wider carrier frequencies and eight, rather than three, time slots.
Code-division multiple-access technology, developed by Qualcomm and used primarily in the US, does not divide a channel into subchannels, like TDMA. Instead, CDMA carries multiple transmissions simultaneously by filling the entire communications channel with data packets coded for various receiving devices. The packets go only to the devices for which they are coded.