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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.
At the time Qualcomm was founded, Jacobs had already been working on addressing telecommunications problems for the military using digital technology to increase the capacity of spectrum. [11] Qualcomm knew that CDMA would greatly increase the efficiency and availability of wireless, but the wireless industry having already invested millions of ...
DS-CDMA (Direct-Sequence Code Division Multiple Access) is a multiple access scheme based on DSSS, by spreading the signals from/to different users with different codes. It is the most widely used type of CDMA. Cordless phones operating in the 900 MHz, 2.4 GHz and 5.8 GHz bands; IEEE 802.11b 2.4 GHz Wi-Fi, and its predecessor 802.11-1999.
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 ...
Carrier-sense multiple access with collision detection (CSMA/CD) is a medium access control (MAC) method used most notably in early Ethernet technology for local area networking. It uses carrier -sensing to defer transmissions until no other stations are transmitting.
CDMA's "cell breathing" characteristic, where a terminal on the boundary of two congested cells will be unable to receive a clear signal, can often negate this advantage during peak periods. A disadvantage of TDMA systems is that they create interference at a frequency that is directly connected to the time slot length.
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 ...
Carrier-sense multiple access (CSMA) is a medium access control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus or a band of the electromagnetic spectrum.