Cell Sites

A cell site is a term used primarily in North America for a site where antennas and electronic communications equipment are placed to create a cell in a network. A cell site is composed of a tower or other elevated structure for mounting antennas, and one or more sets of transmitter/receivers transceivers, digital signal processors, control electronics, a GPS receiver for timing (for CDMA2000 or IS-95 systems), regular and backup electrical power sources, and sheltering.
A synonym for "cell site" is "cell tower", although many cell site antennas are mounted on buildings rather than as towers. In GSM networks, the technically correct term is Base Transceiver Station (BTS), and colloquial British English synonyms are "mobile phone mast" or "base station". The term "base station site" might better reflect the increasing co-location of multiple mobile operators, and therefore multiple base stations, at a single site. Depending on an operator's technology, even a site hosting just a single mobile operator may house multiple base stations, each to serve a different air interface technology (CDMA or GSM, for example). Preserved treescapes can often hide cell towers inside an artificial tree or preserved tree. These installations are generally referred to as concealed cell sites or stealth cell sites.

History of Cell phone

In 1908,U.S. Patent 887,357 for a wireless telephone was issued in to Nathan B. Stubblefield of Murray, Kentucky. He applied this patent to "cave radio" telephones and not directly to cellular telephony as the term is currently understood Cells for mobile phone base stations were invented in 1947 by Bell Labs engineers at AT&T and further developed by Bell Labs during the 1960s. Radiophones have 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 and civil services in the 1950s, while hand-held cellular radio devices have been available since 1973. A patent for the first wireless phone as we know today was issued in US Patent Number3,499,750 to George Sweigart of Euclid, Ohio on June 10, 1969.

In 1945, the zero generation of mobile telephones was introduced. 0G mobile phones, such as Mobile Telephone Service, were not cellular, and so did not feature "handover" from one base station to the next and reuse of radio frequency channels. Like other technologies of the time, it involved a single, powerful base station covering a wide area, and each telephone would effectively monopolize a channel over that whole area while in use. The concepts of frequency reuse and handoff as well as a number of other concepts that formed the basis of modern cell phone technology are first described in U.S Patent 4,152,647 , issued May 1, 1979 to Charles A. Gladden and Martin H. Parelman, both of Las Vegas, Nevada and assigned by them to the United States Government.

This is the first embodiment of all the concepts that formed the basis of the next major step in mobile telephony, the Analog cellular telephone. Concepts covered in this patent (cited in at least 34 other patents) also were later extended to several satellite communication systems. Later updating of the cellular system to a digital system credits this patent. Martin Cooper, a Motorola
researcher and executive is widely considered to be the inventor of the first practical mobile phone for handheld use in a non-vehicle setting. Cooper is the inventor named on "Radio telephone system" filed on October 17, 1973 with the US Patent Office and later issued as US Patent 3,906,166. Using a modern, if somewhat heavy portable handset, Cooper made the first call on a handheld mobile phone on April 3, 1973 to a rival, Dr. Joel S. Engel of Bell Labs.

The first commercial citywide cellular network was launched in Japan by NNT in 1979. Fully automatic cellular networks were first introduced in the early to mid 1980s .The Nordi Mobile Telephone (NMT) system went online in Denmark, Finland, Norway and Sweden in 1981.In 1983, Motorola was the first approved mobile phone by FCC in the United States. In 1984, Bell Labs developed modern commercial cellular technology (based, to a large extent, on the Gladden, Parelman Patent), which employed multiple, centrally controlled base stations (cell sites), each providing service to a small area (a cell). The cell sites would be set up such that cells partially overlapped. In a cellular system, a signal between a base station (cell site) and a terminal (phone) only need be strong enough to reach between the two, so the same channel can be used simultaneously for separate conversations in different cells.

Cellular systems required several leaps of technology, including handover, which allowed a conversation to continue as a mobile phone traveled from cell to cell. This system included variable transmission power in both the base stations and the telephones (controlled by the base stations), which allowed range and cell size to vary. As the system expanded and neared capacity, the ability to reduce transmission power allowed new cells to be added, resulting in more, smaller cells and thus more capacity. The evidence of this growth can still be seen in the many older, tall cell site towers with no antennae on the upper parts of their towers. These sites originally created large cells, and so had their antennae mounted atop high towers; the towers were designed so that as the system expanded—and cell sizes shrank—the antennae could be lowered on their original masts to reduce range.

The first "modern" network technology on digital 2G (second generation) cellular technology was launched by RadioLinja (now part of Elisa Group) in 1991 in Finland on the GSM standard which also marked the introduction of competition in mobile telecoms when Radiolinja challenged incumbent Telecom Finland (now part of TeliaSonera) who ran a 1G NMT network.
The first data services appeared on mobile phones starting with person-to-person SMS text messaging in Finland in 1993. First trial payments using a mobile phone to pay for a Coca Cola vending machine were set in Finland in 1998. The first commercial payments were mobile parking trialled in Sweden but first commercially launched in Norway in 1999. The first commercial payment system to mimick banks and credit cards was launched in the Philippines in 1999 simultaneously by mobile operators Globe and Smart. The first content sold to mobile phones was the ringing tone, first launched in 1998 in Finland. The first full internet service on mobile phones was i-Mode introduced by NTT DoCoMo in Japan in 1999.

In 2001 the first commercial launch of 3G (Third Generation) was again in Japan by NTTDoCoMo on the WWDMA standard.Until the early 1990s, most mobile phones were too large to be carried in a jacket pocket, so they were typically installed in vehicles as carsphones. With the miniaturization of digital components and the development of more sophisticated batteries, mobile phones have become smaller and lighter.
With its use by Nokia as the default ringtone, The Gran Vals by Francisco Tarrega has become arguably the most recognised tune in the world.

Cellphone

Cellular Radio Telephone, also called cellular telephone or cell phone, low-powered, lightweight radio transceiver (combination transmitter-receiver) that provides voice telephone and other services to mobile users. Cellular telephones primarily operate like portable or cordless telephones. However, unlike conventional wire-based cordless phones, cellular telephones are completely portable and do not require proximity to a jack to access the wire-based networks operated by local telephone companies.

A new generation of services for cell phones includes videoconferencing and Internet access with the ability to send e-mail. Cellular telephones have become very popular with professionals and consumers as a way to communicate while away from their regular, wire-based phones—for example, while traveling or when in remote locations lacking regular phone service. As cellular radio service proliferates and achieves greater market penetration, some users have begun to consider it an alternative to conventional wire-based services.

Cellular telephones work by transmitting radio signals to cellular towers. These towers vary in their capability to receive cellular telephone signals. Some towers can receive signals from distances of only 1.5 to 2.4 km (1.0 to 1.5 mi), while others can receive signals from distances as far as 48 to 56 km (30 to 35 mi). The area a tower can cover is referred to as a cell. However, more than one tower may exist in a given cell area.

The cells overlap so that the system can handle increased telephone traffic volume. The towers within these cells are networked to a central switching station, usually by wire, fiber-optic cable, or microwave. The central switching station handling cellular calls in a given area is directly connected to the wire-based telephone system. Cellular calls are picked up by the towers and relayed to another cell telephone user or to a user of the conventional wire-based telephone network. Since the cells overlap, as a mobile caller moves from one cell into another, the towers “hand off” the call so communication is uninterrupted.

Cellular phone networks exist in nearly every metropolitan area throughout the world, and cellular coverage is expanding in rural areas. Due to the convenience and mobility of cellular telephones, users typically pay a higher fee than they would for normal telephone use. A newer generation of cellular radio technology, called Personal Communications Services (PCS), operates much like earlier cellular services, but at higher frequencies, the number of times a radio wave oscillates or completes a cycle, which is measured in a unit known as a hertz (Hz).

(The higher frequencies of PCS operate at around 1900 megahertz [MHz] in the United States.) PCS also utilizes completely digital transmissions, rather than both the analog and digital transmissions that many current cellular telephones use. Digital transmissions convert sound into digital form, which can be transmitted more efficiently than analog signals.

Digital technologies can also generate more channel capacity over the same amount of the radio spectrum.

Cellula Radio Telephone

Both cellular radio and PCS use high-frequency radio waves to transmit calls. High-frequency waves have short wavelengths that pass by a given point at a very high rate. High-frequency waves can provide better sound quality and more reliable short-distance transmission than lower-frequency waves (such as AM radio) as they are less susceptible to sound degradation caused by the noise generated by weather, such as lightning which causes static, and other noise generators such as motors. However, high-frequency signals cannot effectively travel as far as low-frequency signals can.

For cellular networks, the limited range of high-frequency waves is actually advantageous because it means the same frequencies can be reused at nearby locations. Cell phone calls connect with short-range antennas known as towers. If there were only one tower for a large area, more customers would be trying to use the same high-frequency waves, and these waves would tend to overlap and cause interference.

But because cell phone networks establish many towers covering small areas, a smaller number of customers access a given tower, and frequencies can be reused when a cell phone call is handed off from one tower to another as a mobile cell phone user travels. This ability to reuse frequencies is helpful because there are a limited number of radio frequencies available to cell phone companies. It also allows cellular network providers to accommodate a larger number of users.

The transceiver inside a cellular phone is a much more complex device than a conventional phone used over the wire-based network. A cellular telephone has circuitry that creates a unique identity code that is used to locate and track the telephone. This identity code is necessary for coordinating calls to and from the telephone, and for billing such calls.

Because a cellular telephone user may move quite a distance during the duration of a call, the cellular radio network must manage calls from different tower sites as the telephone moves out of the range of one tower and into the range of another tower.

Current cellular telephones offer such features as a memory database for storing frequently called numbers and a lock to deter theft. Most cell phones, whether old or new, also have a small liquid crystal screen to display the telephone number being called or the number from which an incoming call originated. Many newer cell phones can display a short text message, much like a pager displays this information.

Some cellular phones can also access the Internet and display text from Web sites, such as stock quotes and news stories. Internet-capable cell phones can also send and receive e-mail. Because mobile telephones use radio waves to send and receive calls, the device must include a power source. Rechargeable batteries provide the usual source of power, but most cell phones can also be attached to the cigarette lighter in a vehicle or to some other external power device.

Cellular Networks

The cells in a cellular radio network refer to the coverage area of each tower that receives and transmits calls from mobile telephones. The cells are arranged in a honeycomb pattern, and they overlap so that the system can handle increases in anticipated telephone traffic volume.

Network management functions, performed by computers at a central facility known as a Mobile Telephone Switching Office (MTSO), include the ability to measure and compare the transmission quality between a single handset and multiple towers. This function is important so that the MTSO can select the best transmission link between mobile telephones and towers. This optimal link is then used to pass transmissions from one tower to another as the mobile telephone moves between cells.

All cell towers in a given area connect with the MTSO, which in turn has links to the wire-based local exchange carrier that handles normal telephone calls. The link between the MTSO and the wire-based local telephone company is essential for connecting wireless and wire-based calls. The vast majority of calls handled by a cellular radio network either begin on the wire-based network or end there.

First Commercial Cellphone

The first commercial cellular telephones were tested in the late 1970s by Illinois Bell in Chicago, Illinois, and they were a great success. Cellular service carriers began nationwide operations in the mid-1980s operating in the 800- to 900-MHz frequency band. Before the availability of cellular radio service, mobile telephone service consisted of bulky mobile telephone radio units. These two-way radio units communicated with a single antenna in a city or area. The radio signals often interfered with those of other commercial radios, and due to the technology of the day the frequencies could not be reused as they can today. Therefore, limited numbers of channels were available for callers, and the service was unreliable and costly. Because of the consumer demand for cellular telecommunications, the Federal Communications Commission (FCC) in the mid-1990s authorized up to six additional mobile telephone service providers in each service area.

There were more than 120 million wireless subscribers in the United States in 2001, according to the Cellular Telecommunications and Internet Association, with the number of new users increasing significantly each year. Forecasters and regulators did not anticipate this growth, however. Network equipment and start-up costs were substantial, and the cost to consumers was high. Providers had limited their networks to a small group of high-volume business users. Eventually, the providers recognized that their businesses would be more profitable if they created innovative service packages and aggressively marketed their services to the general public. As a result, prices for cellular telephones and network access have dropped considerably.

Cellular radio telephone service has achieved great commercial success because users recognize that mobile telephone access can improve productivity and enhance safety. Delivery drivers, repair technicians, lawyers, and other professionals were early adopters of mobile telephone service. As more geographic areas are covered by cellular networks and as rates drop, new subscribers are buying cellular services for personal security, safety on the road, and general convenience.