CDMA (Code Division Multiple Access) is a multiple access method for the concurrent transmission of data from several transmitters to a single receiver within a frequency band. For this purpose, the narrow band radio signal is mapped (spread) into a wideband radio signal in the transmitter by using a transmitter-specific mapping scheme. If this mapping scheme is known, the receiver can recover the original narrowband signal from the received wideband radio signal. CDMA is used in UMTS for the air interface between the mobile station and the base station. In the case of wideband code division multiple access (WCDMA), separate frequency bands are used for  uplink an downlink, for which reason WCDMA is often called frequency division/code division multiple access (FD/CDMA). With time division/code division multiple access (TC/CDMA), the uplink and downlink are separated by using different time slots

Categories: Cellular
Tags: SIM Card
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