TYPES OF MOBILES
Year Mobile Telephone System
1981------>Nordic Mobile Telephone (NMT)
1983------>Advanced Mobile Phone System (AMPS)
1985------>Total Access Communication Systems (TACS)
1986------>Nordic Mobile Telephony (NMT)
1991------>American Digital Cellular (ADC)
1991------>Global System for Mobile Communication (GSM)
1992------>Digital Cellular System (DCS) 1800
1994------>Japanese Personal Digital Cellular (PDC)
1995------>Personal Communications Service (PCS) 1900 - Canada
1996------>Personal Communications Service (PCS) - USA
What is the History of Cell Phones?
The beginning history of cell phones is based upon radio technology that was developed from the 1940's onward. For instance the beginning of cell phones can be traced to the innovation in taxi cabs, police cars and other service vehicles where two way radios were used to communicate with one another or with a central base. Early cell phone communication technology could be even traced back to individuals with special radios that can patch into a phone line via live operator to make a phone call.
The first official mobile phone was used in Sweden by the Swedish police in 1946. The technology was connected to the telephone network and was distinctive of two way radio technology. The phone was not very practical; it was only able to make 6 phone calls before the car's battery was drained.
The technology of modern cell phones started with the creation of hexagonal cells for mobile phones by D.H. Ring from Bell Labs in 1947, later on another engineer from Bell Labs conceived of cell towers that would transmit and receive signals in three directions instead of normal bi directional antennas. However, although some technologies have been developed, electronics and other technologies would take decades to mature and to be developed. For instance, the electronics that were used in the first cell phones were first developed in the 1960's
By 1967, mobile phone technology was available; however, the user had to stay within one cell area. Cell areas which were serviced by a base station were unable to hand off cellular phone calls from one base station to another. While you could make a phone, call, you weren't able to continue the call after you reached a set range. In 1970, Amos Edward Joel, who also was an engineer at Bell Labs, developed the call handoff system. This technology facilitated continuity of a phone call from one area to another without dropping the phone call.
While the technology had been developed, it wasn't until 1971 that AT&T submitted a request to the FCC for cellular service. It took more than 10 years for an approval and in 1982; the FCC allocated the frequencies of 824-894 MHZ Band to Advanced Mobile Phone Service (AMPS). From 1982 to 1990, AMPS was an analog service, Digital AMPS came online as of 1990.
Throughout the decades, there have been many technologies that existed that made mobile phones available. Most of the time, these phones were installed in vehicles due to the large battery requirements. For instance, the MTA (Mobile Telephone System A) developed by Eriksson was available in Sweden in 1950's. Unfortunately, it weighed over 80 pounds, later versions however weighed around the 20 pound range, still making it ineffective for truly portable devices that are used today.
First Generation Cell Phones
In 1983, Motorola unveiled to the world, the first truly portable cellular phone. It was called the Motorola DynaTAC 8000X. It was approved for use in the United States by the FCC. Motorola developed the technology for cellular phones for decades and this particular phone took 15 years to come to market at an expense of over 100 million dollars in research costs. The DynaTAC800X was extremely lightweight for its time and only weighed about 28 ounces. It was 13 inches x 1.75 inches x 3.5 inches and was known as the Brick for its shape. It was largely developed with the help of Dr. Martin Cooper of Motorola.
From 1983 to the end of the 1980's cell phones grew in popularity due to the innovations in cellular networks that were able to handle phone calls in either one area or hand them off to other areas. While most cell phones weren't made to be carried in your hand, all phones were made for permanent installation in the car. For a while the term "car phone" was extremely popular. Besides car phones, there were a few models that came in tote bag type configurations that can easily hook up to a car's battery, via the DC outlet to make calls. There were also a few models that came as briefcases, to hold large batteries necessary to make phone calls.
Second Generation Cellular Phones
Cellular phones from the early 1990's are considered being second generation (2G) and they were able to work on mobile phone systems such as GSM, IS-136 (TDMA) and IS-95 (CDMA). Digital mobile phone networks were in use in the United States in 1990 and in Europe by 1991. 2G mobile phones use digital circuit switched transmissions. This ultimately enabled quicker network signaling, lowering the amount of dropped calls and increasing call quality. As 2G digital networks were online, most of the time, they replaced analog network frequencies, effectively making them obsolete.
Phones based on 2G technology were much smaller than the brick telephones of the mid to late 80's. Most 2G cellular phones were usually in the range of 100 to 200 grams, plus they were hand held devices that were truly portable without the need for a large battery. Advances in battery technology, as well as computer chip technology also helped to make 2G cell phones much smaller than their predecessors. With these innovations, cell phone usage soared.
Third Generation Cellular Phones
Third Generation cellular phones is the technology that is currently available today and it is commonly referred to as 3G. While 3G came only a few years after 2G, mainly due to many innovations in technology and services, standards for 3G are usually different depending on the network.
It is usually stated that 3G is not necessarily a rigid standard, but is a set of requirements that most networks and cell phone providers follow. There are two main requirements; they include 2 Megabits of maximum data rate indoors and 384 kbits for outdoor use. 3G mobile phones usually include innovations to receive much more than phone calls, for instance, SMS text is available and some 3G phones also offer email and Internet access. Currently technologies are continuing to improve and new innovations such as streaming radio and TV, as well as Wifi are currently breaking into the market.
Other Mobile Telephone Systems
Many mobile telephone systems exist outside the United States, including NMT, TACS/ETACS, and JTACS. New systems are constantly in development.
Early Mobile Telephone Technologies
Before there were cellular telephone systems, there was MTS (Mobile Telephone Service) and IMTS (Improved Mobile Telephone Service). These early systems have ceased operations.
FDM, TDMA, and CDMA Mobile Telephone Technologies
In a FDM system, the available frequency is divided into channels. Each conversation is given a channel. When the system runs out of channels in a given area, no more telephone calls can be connected. In this way, FDM operates much like the channel button on your television set. The AMPS and NAMPS mobile telephone systems utilize FDM.
In a TDMA system, your encoded voice is digitized and then placed on a radio-frequency (RF) channel with other calls. This is accomplished by allocating time slots to each call within the frequency. In the D-AMPS (Digital AMPS) system, each 30kHz carrier frequency is divided into three time slots. In the GSM and PCS systems, each 200kHz carrier is divided into eight time slots. The D-AMPS, D-AMPS 1900, GSM, PCS and iDEN systems all utilize TDMA.
In a CDMA system, your encoded voice is digitized and divided into packets. These packets are tagged with "codes." The packets then mix with all of the other packets of traffic in the local CDMA network as they are routed towards their destination. The receiving system only accepts the packets with the codes destined for it.
Analog systems are FDM. Digital systems can utilize either TDMA or CDMA.
FDM systems typically allow one call per 10Khz or 30Khz of spectrum. Early TDMA systems tripled the capacity of FDM systems. Recent advances in TDMA promise to provide forty times the carrying capacity of FDM systems. CDMA promises to improve on the results of TDMA.
Analog and Digital Mobile Telephone Technologies
Mobile telephone systems are either analog or digital. In analog systems, voice messages are transmitted as sound waves. When you speak into an analog mobile telephone, your voice wave is linked to a radio wave and transmitted. In digital systems, voice messages are transmitted as a stream of zeroes and ones. When you speak into a digital mobile telephone, your voice wave is converted into a binary pattern before being transmitted.
Mobile Telephony questions
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