Introduction to Mobile Communication & a brief history
The ever-changing world of mobile communication is often difficult to make sense of. Mobile technology has and is advancing at such an accelerating pace that the customer often tends to get confused.
In order to have a clear view of how mobile communication has advanced overtime, some information regarding the previous technologies and how they have evolved to meet the changing needs of the customer is necessary.
1941- The first microwave transmission was made
1946-First radio telephone connected to the public telephone network. This public mobile telephone service was introduced in twenty-five major American cities. Each system was based on a single high power transmitter, supported by a large tower in order to accommodate the communication in a distance of over 50 km. Even though the actual telephone grade speech occupies only 3 KHz of base band spectrum, the early FM push-to talk telephone systems of the late 1940’s utilized a bandwidth of 120 KHz in order to accommodate for the noise in the filters and the amplifiers.
1950-FCC doubles the number of mobile telephone channels per market, enabling the FM bandwidth requirements to be cut to 30 KHz.
1954- First transistor radio is introduced by Sony.
1958-Data is sent over normal telephone circuits.
1960-Electronic telephone exchange introduced by AT&T Bell Laboratories. Also in the 1960s automatic channel trunking was introduced and implemented under the label IMTS (Improved Mobile Telephone Service). During the same time, various telecommunication companies throughout the world developed the theory and techniques of cellular radiotelephony. This concept utilized the ingenious idea of breaking up a coverage zone into smaller cells. These cells would be able to reuse portions of the spectrum thus increasing the spectrum usage vastly.
1968- AT&T proposed the concept of cellular mobile system to the FCC. However, the technology was not available to implement the mobile telephony until the 1970s and thus the first cellular phones were introduced in 1979.
1979- The world’s first cellular system implemented by the Nippon Telephone and Telegraph Company (NTT) in Japan was introduced. This system used 600 FM channels with 25 KHz allocated for each one-way link in the 800 MHz band.
1983- FCC allocated 666 duplex channels, i.e. 40 MHz of spectrum in the 800 MHz band. Each channel had a one way bandwidth of 30 KHz for total spectrum occupancy of 60 KHz for each duplex channel. According to the FCC rules, each city or market was only allowed to have two cellular radio system providers which would insure some level of competition.
1991- The first US digital Cellular (USDC) system hardware was installed which allowed cellular operators to replace some single user analog channels with digital channels which had the ability to support three users within the same 30 KHz bandwidth.
1995- Personal Communication Service Licenses were auctioned to wireless providers and these have spawned new services that complement as well as compete with cellular and SMR (Specialized Mobile Radio service).
1999- First phase of IMT 2000 standards for 3G released.
2000- First cellular subscribers exceed 700 million.
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