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Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel.
The first commercial-scale CDMA cellular network was created in Hong Kong in 1995. [76] On July 21, 1995, Primeco, which represented a joint venture of Bell Atlantic, Nynex, US West and AirTouch Communications, announced it was going to implement CDMA-based services [18] on networks in 15 states. [76]
IS-95 was the first ever CDMA-based digital cellular technology. It was developed by Qualcomm using Code Division Multiple Access and later adopted as a standard by the Telecommunications Industry Association in TIA/EIA/IS-95 release published in 1995.
CDMA2000 1X (IS-2000), also known as 1x and 1xRTT, is the core CDMA2000 wireless air interface standard.The designation "1x", meaning 1 times radio transmission technology, indicates the same radio frequency (RF) bandwidth as IS-95: a duplex pair of 1.25 MHz radio channels. 1xRTT almost doubles the capacity of IS-95 by adding 64 more traffic channels to the forward link, orthogonal to (in ...
The principle of CDMA is based on spread spectrum technology developed for military use during World War II and improved during the Cold War into direct-sequence spread spectrum that was used for early CDMA cellular systems and Wi-Fi. DSSS allows multiple simultaneous phone conversations to take place on a single wideband RF channel, without ...
The CDMA network has since been replaced by an 850 MHz UMTS network, Next G. U.S. Virgin Islands: 1986 [27] Israel: 1986 [27] Pelephone – began offering nationwide AMPS service in Israel in 1986. In the mid-1990s it converted to CDMA (IS-95 and later EV-DO) and in the mid-2000s converted to UMTS. Bolivia: 1991-1992 [34] Cayman Islands: 1987 [27]
cdmaOne network structure. The IS-95 standards describe an air interface, [1] a set of protocols used between mobile units and the network. IS-95 is widely described as a three-layer stack, where L1 corresponds to the physical layer, L2 refers to the Media Access Control (MAC) and Link-Access Control (LAC) sublayers, and L3 to the call-processing state machine.
The OFDM-based multiple access technology OFDMA is also used in several 4G and pre-4G cellular networks, mobile broadband standards, the next generation WLAN and the wired portion of Hybrid fiber-coaxial networks: [citation needed] The mobility mode of the wireless MAN/broadband wireless access (BWA) standard IEEE 802.16e (or Mobile-WiMAX)