History of Cell Phones
The history of mobile phones records the development of interconnection between the public switched telephone systems to radio transceivers. From the earliest days of transmitting speech by radio, connection of the radio system to the telephone network had obvious benefits of eliminating the wires. Early systems used bulky, high power consuming equipment and supported only a few conversations at a time, with required manual set-up of the interconnection. Today cellular technology and microprocessor control systems allow automatic and pervasive use of mobile phones for voice and data.
The transmission of speech by radio has a long and varied history going back to Reginald Fessenden's invention and shore-to-ship demonstration of radio telephony, through the Second World War with military use of radio telephony links. Mobile telephones for automobiles became available from some telephone companies in the 1950s. Hand-held radio transceivers have been available since the Second World War. Mobile phone history is often divided into generations (first, second, third and so on) to mark significant step changes in capabilities as the technology improved over the years.
Pioneers of Radio telephony
By 1930, telephone customers in the United States could place a call to a passenger on a liner in the Atlantic Ocean. Air time charges were quite high, at $7(1930)/minute (about $92.50/minute in 2011 dollars). In areas with Marine VHF radio and a shore station, it is still possible to arrange a call from the public telephone network to a ship, still using manual call set-up and the services of a human marine radio operator.
However it was the 1940s onwards that saw the seeds of technological development which would eventually produce the mobile phone that we know today. Motorola developed a backpacked two-way radio, the Walkie-Talkie and a large hand-held two-way radio for the US military. This battery powered "Handie-Talkie" (HT) was about the size of a man's forearm.
In 1946 in St. Louis, the Mobile Telephone Service was introduced. Only three radio channels were available, and call set-up required manual operation by a mobile operator.  Although very popular and commercially successful, the service was limited by having only a few voice channels per district.
In 1964 Improved Mobile Telephone Service was introduced with additional channels and more automatic handling of calls to the public switched telephone network. Even the addition of radio channels in three bands was insufficient to meet demand for vehicle-mounted mobile radio systems.
In 1969, a patent for a wireless phone using an acoustic coupler for incoming calls was issued in US Patent Number 3,449,750 to George Sweigert of Euclid, Ohio on June 10, 1969, but did not include dialing a number for outgoing calls.
In December 1947, Douglas H. Ring and W. Rae Young, Bell Labs engineers, proposed hexagonal cells for mobile phones in vehicles. Philip T. Porter, also of Bell Labs, proposed that the cell towers be at the corners of the hexagons rather than the centers and have directional antennas that would transmit/receive in three directions (see picture at right) into three adjacent hexagon cells. At this stage, the technology to implement these ideas did not exist, nor had the frequencies been allocated. Several years would pass before Richard H. Frenkiel and Joel S. Engel of Bell Labs developed the electronics to achieve this in the 1960s.
In all these early examples, a mobile phone had to stay within the coverage area serviced by one base station throughout the phone call, i.e. there was no continuity of service as the phones moved through several cell areas. The concepts of frequency reuse and handoff, as well as a number of other concepts that formed the basis of modern cell phone technology, were described in the 1970s. In 1970 Amos E. Joel, Jr., a Bell Labs engineer, invented an automatic...
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