This technology is also known as international mobile

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Unformatted text preview: three communications simultaneously. This technology is primarily used in the US. 2. GSM. Global System for Mobile (GSM) communications technology is also based on time-division multiplexing of each cellular channel. However, it uses wider carrier frequencies than TDMA are divides each cellular channel into eight time slots, rather than three. Hence, GSM technology can handle eight communications simultaneously. This technology is primarily used in Europe and Asia. 3. CDMA. Code-Division-Multiple-Access (CDMA) technology does not divide a channel into sub-channels, like TDMA or GSM. Instead, it 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. This technology is primarily used in the US. As upgrades to 2G technologies, 2.5G technologies were developed to provide more bandwidth for higher data transfer rates. 2.5G uses High-Speed-CircuitSwjtched-Data (HSCSD) technology, which is basically an extension of GSM technology that can offer throughput of up to 384 Kbps. Although 2.5G offers more bandwidth than 2G, it is less than that offered by 3G. However, since 2.5G uses existing 2G spectra and does not require: entirely new network infrastructure, it can be implemented faster and less expensively than 3G. 2.5G comprises of the following three primary standards: 1. iDEN. Integrated Digital Enhanced Network (iDEN) is a GSM upgrade that uses enhanced compression and modulation technologies to deliver data transfer rates of 64 Kbps. It is primarily used in North America, South America, China, and Japan. 2. GPRS. General Packet Radio Service (GPRS) is another GSM upgrade that offers data transfer rates of up to 171 Kbps. It can thus be used for applications such as videoconferencing and interacting with multimedia web sites. GPRS reallocates several GSM time slots for voice to data uses, thereby increasing data rates but decreasing voice rates. It...
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This document was uploaded on 04/07/2014.

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