Cellular telephone (cellular telephone) is a long-range, portable, wireless electronic telephone that can seamlessly switch antenna connections from one radio-receiving cell to another radio-receiving cell during travel without interrupting or lose the current call.
In addition to the standard voice function of a telephone, newer cell phones (cell phone) have features such as SMS for text messages, MMS for multimedia messages, radio, games, Internet connectivity for email, browsing, blogging, playback music (MP3), memo recording, built-in cameras and camcorders, ringtones, personal organizers, Push-to-Talk (PTT), Bluetooth and infrared connectivity, call logs, video streaming, video download, video call and also they serve as wireless modems for PCs that may be connected to the Internet.
Power for a cell phone (cell phone) is drawn from rechargeable batteries, which can be recharged from the mains, from a USB port, or from a car cigarette lighter. Nickel metal hydride batteries were the most common types of batteries, which due to the “memory effect” (the user can recharge only when the entire battery is depleted) were replaced by lithium-ion batteries, which did not suffer from any memory effect .
Cellular telephones (cellular telephone) arose due to the invention of hexagonal cells in 1947, for base stations by engineers at Bell Labs at AT&T. This was further developed during the 1960s by Bell Labs. During a call, the channel frequency could not be automatically changed from one cell (base station coverage area) to another cell (base station coverage area). ) as the person traveled from the area of one cell to the area of another cell. Amos Joel of Bell Labs came up with a revolutionary invention and called it “call transfer” whereby the channel frequency could be automatically switched from one cell to another during the same call, as the mobile user traveled from one cell to another. . Due to their heavy construction, these phones were mainly used in automobiles.
The first cellular telephone practical in a non-vehicular environment, and that could be handheld, was invented by Martin Cooper, the General Manager (Communications Division) of Motorola, who manufactured the world’s first handheld cellular telephone (cellular phone). April 3, 1973.
The technology with which the cell phone (cell phone) works depends on the mobile phone operator; however, they all use electromagnetic radio waves, which are in contact with a cell site (base station). The base station is made up of several antennas that are mounted on a pole, tower, or building. Cell sites are distributed within 5 to 8 miles (approximately 8 to 13 km) of each other. The cell phone’s low power transceiver transmits voice and data to the nearest cell site. During the movement, the cell phone will “transfer” the information to another cell site. Mobile phone operators use many technologies to keep digitized data flowing smoothly from cell phone to cell site and vice versa.
Wireless phone technologies are grouped under headings known as generations, starting with generation zero or 0G. The current generation is 4G; however, there are old cell phones (cell phone) that still work with 1G, 2G and 3G technologies. The wireless telephone technologies used in each generation are as follows:
0G: PTT, MTS, IMTS, AMTS, OLT, MTD, Autotel/PALM, ARP
1G: NMT, AMPS/TACS/ETACS, Hicap, CDPD, Mobitex, DataTac
2G: GSM, iDEN, D-AMPS, IS-95/cdmaOne, PDC, CSD, PHS, GPRS, HSCSD, WiDEN, CDMA2000 1xRTT/IS-2000, EDGE (EGPRS)
3G: W-CDMA, UMTS (3GSM), FOMA, TD-CDMA/UMTS-TDD, 1xEV-DO/IS-856, TD-SCDMA, GAN (UMA), HSPA, HSDPA, HSUPA, HSPA+, HSOPA
4G: UMB, UMTS Revision 8 (LTE), WiMAX
Frequency bands: SMR, Cellular, PCS
The impact of cell phone (cell phone) use on human health has been of great concern around the world. Research studies in Copenhagen, from the Danish Institute of Cancer Epidemiology, the National Cancer Institute and the Cancer Research Institute, do not establish any link between cancer and cell phone use. However, an intergovernmental agency IARC (International Agency for Research on Cancer) which is part of the United Nations World Health Organization, conducted a study of 4,500 users and found a statistically significant link between the use of cell phones and the frequency of tumors. More research is being done.
Cell phone (cell phone) use and driving is a common phenomenon throughout the world. Some jurisdictions have prohibited the use of handheld phones while driving, but allowed hands-free cell phone use while driving. However, studies have found that the distraction is caused by the conversation itself; Therefore, both handheld and hands-free mobile phones contribute to traffic accidents. More studies are being done on cell phone use and driving.
Nokia Corporation is currently the world’s largest manufacturer of cell phones (cellular phones). Other notable cell phone manufacturers, in alphabetical order, include 3G, Audiovox (now UT Starcom), Benefon, BenQ-Siemens, Fujitsu, High Tech Computer Corporation (HTC), Kyocera, LG Mobile, Motorola, NEC, Panasonic (Matsushita Electric ) ), Pantech Curitel, Philips, Research In Motion, Sagem, Samsung, Sanyo, Sharp, Siemens, Sierra Wireless, SK Teletech, Sony Ericsson, T&A Alcatel, Toshiba and Verizon.
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