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ØFrequency Division Multiplexing
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Among all the communication devices and services, cellular phone has been increasingly popular for personal communication. Cellular phone technology has given us the freedom to communicate with each other and obtain much needed information from anywhere in the cellular phone provider’s network wirelessly. Today, there are over 1.3 billion cellular phone users worldwide and one hundred and forty million users alone in the United States. These growing numbers are approaching to the total number of total land or wired phone users. Today, cellular phones are not solely used for wireless voice communication but also they are capable of accessing the Internet and retrieving high bandwidth data from various networks. There are Four common technologies used by cell-phone networks for transmitting information: Ø Frequency Division Multiplexing (FDMA) Ø Time Division Multiplexing (TDMA) Ø Code Division Multiplexing (CDMA) Ø Global System for Mobile Communications (GSM) FDMA is used for analog transmission and TDMA, CDMA and GSM are used for digital data transmission. Because of the least efficiency of FDMA, it has become an unpopular technology for data transmission. Within the United States, TDMA and CDMA are the most popular digital cellular technologies. However, Global System for Mobile Communications (GSM) is very popular in Europe, Asia and Australia. GSM technology is based on TDMA but implements TDMA in a different way. The power of GSM phone relies on its compatibility- the one GSM phone will be working anywhere (except 1900 MHz phones) provided that the standard is supported. The latest technological advancement in cellular technology is Personal Communication Services (PCS). It is combined of TDMA, CDMA and GSM and uses frequency between 1.8 to 1.9 GHz. The PCS technology enable us for a higher quality of voice, increased privacy, increased security, long battery life and one hundred percent digital technology. Now lets take a brief look at the most popular GSM and the latest invented PCS technology. Global System for Mobile Communications (GSM): During the 1980s, many European countries were working on different cellular technologies independently. Each country was emerging with new technology, which in turn was not compatible country to country. In 1982 European authorities set Global System for Mobile Communications as the official common standard for inter-country connectivity. This dissolved the issue of compatibility. Now one single phone could be used throughout the Europe and other countries of the world, which supports this technology.
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