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History Of Mobile Phones What was possibly the first real mobile phone, in the sense that it was connected to the telephone network, was tested by the Swedish police in 1946. Half dozen calls could be made before the (car's) battery ran out. Radiophones began to be publicly available, in the US, at the end of the 1940s[1] (http://www.itu.int/osg/spu/imt-2000/technology.html) though the distinction between such phones and a two way radio becomes blurry since special systems are required to "patch" into the phone network with the assistance of human operators. Recognisable mobile phones with direct dialling have existed at least since the 1950s Modern mobile telephony is often considered to have started on April 3, 1973, when Martin Cooper – then an employee of Motorola – placed the first call to the company's rival AT&T's Bell Labs, while walking the streets of New York City. Mobile phones began to proliferate through the 1980s with the introduction of "cellular" phones based on cellular networks with multiple base stations located relatively close to each other, and protocols for the automated "hand-off" between two cells when a phone moved from one cell to the other. At this time analog transmission was in use in all systems. Mobile phones were somewhat larger than current ones, and many were designed for permanent installation in cars (hence the term car phone), or as "transportable" phones the size of a briefcase. These systems (NMT, AMPS, TACS) later became known as first generation mobile phones. In October 1981 the first cell phone network with automatic roaming between countries was started in the Nordic countries; it was a NMT system. It became the start of the cell phone boom and became much more successful then ever anticipated. In the 1990s, second generation (2G) mobile phone systems such as GSM, IS-136 ("TDMA"), iDEN and IS-95 ("CDMA") began to be introduced. The first digital cellular phone call was made in the United States in 1990, in 1991 the first GSM network opened in Europe. 2G phone systems characterised by digital circuit switched transmission and the introduction of advanced and fast phone to network signalling. In general the frequencies used by 2G systems were higher though with some overlap, for example the 900 MHz frequency range was used for both 1G and 2G systems in Europe and so such 1G systems were rapidly closed down to make space for 2G systems. Coinciding with the introduction of 2G systems were trends which meant that the larger "bricks" disappeared and tiny 100–200g hand-held devices became the norm. These trends included technology improvements such as better battery technologies and lower power electronics, but also are largely related to the higher density of cellular sites caused by increasing usage levels. In most of Europe, wealthy parts of Asia, and Australasia, mobile phones are now virtually universal, with the majority of the adult, teenage, and even child population owning one. They are less common in the United States — while widely available, market penetration is lower than elsewhere in the developed world (around 66 percent of the U.S. population as of 2003). Reasons advanced for this include incomplete coverage, relatively high minimum monthly service charges (around $30), and the availability of relatively low-cost fixed-line networks (around $30 for unlimited local calling). Not long after the introduction of 2G networks, projects began to develop 3G systems. Inevitably there were many different standards with different contenders pushing their own technologies. Quite differently from 2G systems, however, the meaning of 3G has been standardised in the IMT-2000 standardisation process. This process did not standardise on a technology, but rather on a set of requirements (2Mb/s maximum data rate indoors, 384Kb/s outdoors, for example). At that point, the vision of a single unified worldwide standard broke down and several different standards have been introduced. During the development of 3G systems, 2.5G systems such as CDMA-2000 1X and GPRS were developed as extensions to existing 2G networks. These provide some of the features of 3G without fulfilling the promised high data rates or full range of multimedia services. E.g. CDMA2000-1X delivers theoretical maximum data speeds of up to 307 kbit/s. Just beyond these is the EDGE system which in theory covers the requirements for a 3G system, but is so narrowly above these that any practical system would be sure to fall short. At the beginning of the 21st century, 3G mobile phone systems such as UMTS and CDMA-2000 1xEV-DO have now begun to be publicly available. The final success of these systems is still to be determined.
Rrticle originally published on http://en.wikipedia.org
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