Cellular Phone Reviewed by Momizat on . A mobile phone is a telephone that can make and receive calls over a radio frequency carrier while the user is moving within a telephone service area. The radio A mobile phone is a telephone that can make and receive calls over a radio frequency carrier while the user is moving within a telephone service area. The radio Rating: 0
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Cellular Phone

A mobile phone is a telephone that can make and receive calls over a radio frequency carrier while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Most modern mobile telephone services use a cellular network architecture, and therefore mobile telephones are often also called cellular telephones or cell phones. In addition to telephony, modern mobile phones support a variety of other services, such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming, and photography.

Mobile phones which offer these and more general computing capabilities are referred to as The first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing c. 4.4 lbs (2 kg). In 1983, the DynaTAC 8000x  was the first commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion, penetrating 100% of the global population and reachingthe bottom of the economic pyramid. In 2014, the top mobile phone manufacturers were

History

Main article: History of mobile

Martin Cooper of Motorola made the first publicized handheld mobile phone call on a prototype DynaTAC model on April 4, 1973. This is a reenactment in 2007. A handheld mobile radio telephone service was envisioned in the early stages of radio engineering.

In 1917, Finnish inventor Eric Tigerstedt filed a patent for a “pocket-size folding telephone with a very thin carbon microphone”. Early predecessors of cellular phones included analog radio communications from ships and trains.

The race to create truly portable telephone devices began after World War II, with developments taking place in many countries. The advances in mobile telephony have been traced insuccessive “generations”, starting with the early “0G” (zeroth generation) services, such as Bell System’s Mobile Telephone Serviceand its successor, the Improved Mobile Telephone Service. These “0G” systems were not cellular, supported few simultaneous calls, and were very expensive.

The Motorola DynaTAC 8000X. First commercially available handheld cellular mobile phone, 1984.The first handheld mobile cell phone was demonstrated by Motorola in 1973. The first commercial automated cellular network was

launched in Japan by Nippon Telegraph and Telephone in 1979. This was followed in 1981 by the simultaneous launch of theNordic

Mobile Telephone (NMT) system in Denmark, Finland, Norway and Sweden. Several other countries then followed in the early to mid-1980s. These first-generation (1G) systems could support far more simultaneous calls, but still used analog technology.

In 1991, the second-generation (2G) digital cellular technology was launched in Finland by Radiolinja on the GSM standard. This sparked competition in the sector as the new operators challenged the incumbent 1G network operators.

Ten years later, in 2001, the third generation (3G) was launched in Japan by NTT DoCoMo on the WCDMA standard. This was followed by 3.5G, 3G+ or turbo 3G enhancements based on the high-speed packet access (HSPA) family, allowing UMTS networks to have higher data transfer speeds and capacity.

By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications, such as streaming media. Consequently, the industry began looking to data-optimized fourth-generation technologies,

with the promise of speed improvements up to ten-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard, offered in North America by Sprint, and the LTE standard, first offered in Scandinavia by TeliaSonera.

Health effects

Main article: Mobile phone radiation and health Further information: Mobile phones on aircraft The effect of mobile phone radiation on human health is the subject of recent interest and study, as a result of the enormous increase in mobile phone usage throughout the world. Mobile phones use electromagnetic radiation in the microwave range, which some believe may be harmful to human health.

A large body of research exists, both epidemiological and experimental, in non-human animals and in humans. The majority of this research shows no definite causative relationship between exposure to mobile phones and harmful biological effects in humans. This is often paraphrased simply as the balance of evidence showing no harm to humans from mobile phones, although a significant number of individual studies do suggest such a relationship, or are inconclusive. Other digital wireless systems, such as data communication networks, produce similar radiation.

On 31 May 2011, the World Health Organization stated that mobile phone use may possibly represent a long-term health risk, classifying mobile phone radiation as “possibly carcinogenic to humans” after a team of scientists reviewed studies on mobile phone safety. The mobile phone is in category 2B, which ranks it alongside coffee and other possibly carcinogenic substances. Some recent studies have found an association between mobile phone use and certain kinds of brain and salivary gland tumors. Lennart Hardell and other authors of a 2009 meta-analysis of 11 studies from peer-reviewed journals concluded that cell phone usage for at least ten years “approximately doubles the risk of being diagnosed with a brain tumor on the same (‘ipsilateral’) side of the head as that preferred for cell phone use” . One study of past mobile phone use cited in the report showed a “40% increased risk for gliomas (brain cancer) in the highest category of heavy users (reported average: 30 minutes per day over a 10‐year period)”.

This is a reversal of the study’s prior position that cancer was unlikely to be caused by cellular phones or their base stations and that reviews had found no convincing evidence for other health effects.   However, a study published 24 March 2012 in the British Medical Journal questioned these estimates, because the increase in brain cancers has not paralleled the increase in mobile phone use. Certain countries, including France, have warned against the use of mobile phones by minors in particular, due to health risk uncertainties. Mobile pollution by transmitting electromagnetic waves can be decreased up to 90% by adopting the circuit as designed in mobile phone (MS) and mobile exchange (BTS, MSC etc.).

 

source wikipedia

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