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Code Division Multiple Access (CDMA) is a wireless transmission technology, which breaks digital voice information into separate conversations according to a number of codes.
CDMA is the second most popular 2G wireless voice technology in the world, after GSM, and is available from numerous providers in the United States, Canada, South Korea, and other countries.
Code division multiple access (CDMA) is the current name for the cellular technology originally known as IS-95. This technology is in competition with GSM for leadership in the global cellular technology market. Developed by Qualcomm and enhanced by Ericsson, CDMA is characterized by high capacity and small cell radius, employing spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code). By contrast, time division multiple access divides access by time, while frequency-division multiple access divides it by frequency. CDMA is a form of "spread-spectrum" signaling, since the modulated coded signal has a much higher bandwidth than the data being communicated.
An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.
CDMA also refers to digital cellular telephony systems that use this multiple access scheme, as pioneered by QUALCOMM, and W-CDMA by the International Telecommunication Union (ITU).
CDMA has been used in many communications and navigation systems, including the Global Positioning System and the OmniTRACS satellite system for transportation logistics.
Use in mobile telephony
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