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CDMA is analogous to the last example where people speaking the same language can understand each other, but other languages are perceived as noise and rejected. 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 communicate.
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.
In 3G, the most prevalent technology was UMTS with CDMA-2000 in close contention. All radio access technologies have to solve the same problems: to divide the finite RF spectrum among multiple users as efficiently as possible. GSM uses TDMA and FDMA for user and cell separation. UMTS, IS-95 and CDMA-2000 use CDMA. WiMAX and LTE use OFDM.
Hedy Lamarr (/ ˈ h ɛ d i /; born Hedwig Eva Maria Kiesler; November 9, 1914 [a] – January 19, 2000) was an Austrian-born American actress and inventor. After a brief early film career in Czechoslovakia, including the controversial erotic romantic drama Ecstasy (1933), she fled from her first husband, Friedrich Mandl, and secretly moved to Paris.
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 ...
Cellular network standards and generation timeline. 3G technology was the result of research and development work carried out by the International Telecommunication Union (ITU) in the early 1980s. 3G specifications and standards were developed in fifteen years. The technical specifications were made available to the public under the name IMT-2000.
In 2001, NTT Docomo premiered the world's first Third Generation mobile phone service (3G), using W-CDMA technology called FOMA. In 2002, KDDI started 3G service in Okinawa, using CDMA2000 technology. In the same year, J-Phone started 3G service using W-CDMA technology. In 2003, J-Phone changed its name to Vodafone.
The antecedent to 1G technology is the mobile radio telephone (i.e. "0G"), where portable phones would connect to a centralised operator. 1G refers to the very first generation of cellular networks. [2] Cellular technology employ a network of cells throughout a geographical area using low-power radio transmitters. [1]