It has been known for centuries that information is power. What was not known for centuries was how to store information and knowledge in such a way that it can be accessed by everybody from anywhere, any time, convergence of information technology and communication technology has created ways to address those challenges. Today we can have information access from anywhere all the time even at a state of mobility.
In last two centuries, mobility has been redefined both physical and virtual objects are now mobile. Mobility of physical objects release to movement of matters, whereas movements of virtual objects release to movements of bits and bytes.
On October 4, 1957 the USSR launched the Sputnik. It was the first artificial Earth sattelite launched from Baikobour Cosmodrome in Kazakhstan. This demonstrated the technological superiority of USSR. In response to this they formed the Advance Research Projects Agency with in the Department of Defence. ARPA was to establish US lead in Science and Technology. With the evolution of computers and the Packet Switched Networks, movements of bits and bytes moved to a new stage of maturity over a last 175 years virtual reality evolved from ringing a bell to a mobile phone through mobile computing.
To take advantage of this growing market, each country in Europe developed its own analog mobile system. These cellular system developed by each country in Europe were mutually incompatible. These incompatibilities made the operation of the mobile equipment limited to national boundaries. Also, a mobile subscriber of one network cannot use the same desire in another network in another country.
To cope with these problems Europeans decided to evolve a standard for mobile phone technology. In 1982, the Conference of European Posts and Telegraph (CEPT) formed a study group called the Groups Special Mobile (GSM) to develop a standard for pan-European mobile system. In 1989, GSM responsibility was transferred to the European Telecommunications Standards Units (ETSI) and GSM became a technical committee within ETSI.
In 1990, phase l of the GSM specifications were published Commercial Service of GSM started in 1991. Although standardized in Europe, GSM became popular outside Europe as well. GSM was renamed as Global System For Mobile Communications. In the beginning of 1994, there were 1.3 million subscribers worldwide.
In last two centuries, mobility has been redefined both physical and virtual objects are now mobile. Mobility of physical objects release to movement of matters, whereas movements of virtual objects release to movements of bits and bytes.
On October 4, 1957 the USSR launched the Sputnik. It was the first artificial Earth sattelite launched from Baikobour Cosmodrome in Kazakhstan. This demonstrated the technological superiority of USSR. In response to this they formed the Advance Research Projects Agency with in the Department of Defence. ARPA was to establish US lead in Science and Technology. With the evolution of computers and the Packet Switched Networks, movements of bits and bytes moved to a new stage of maturity over a last 175 years virtual reality evolved from ringing a bell to a mobile phone through mobile computing.
The Convergence Leading To ICT
The first step towards the convergence between telecommunications and IT happened in 1965 when AT & T used computers to do switching in Electronic Switching System ( ESS). On the other hand packet switch network was bringing Communication, closer to computers. The World Wide Web (WWW), which was started by Tim Berners Lee in 1989 as a text processing software, brought those two faculties of technology together and established Internet as a powerful media. The Internet meets four primary worlds of the society - Communication, Knowledge sharing, Commerce and Entertainment. This convergence is called information and communication technologies (ICT), through ICT we are now moving towards an information based society. ICT will address the need to access data, information and knowledge form anywhere, any time.
WIRELESS THE BEGINNING
IN 1947 researchers at AT&T Bell labs convinced the idea of cellular phones. They realized that by using Small Services Areas or Cells they can reuse the frequency. This in turn can enhance the traffic capacity of mobile phones. AT&T requested the Federal Communication Commission (FCC) to allocate a large number of radio spectrum frequencies so that widespread mobile phone service would become feasible. FCC is a government agency in United States who regulates the usage and licensing of frequency bands. Every country has its regulatory agencies like FCC. In India the regulatory authority is TRAI.
Evolution of Wireless Networks
The first wireless network was commissioned in Germany in 1958. It was called A-Netz and used Analog Technology at 160 mhz. Only outgoing calls were possible in this network. That to say that connection setup was possible from the mobile station only. This system evolved into B-Netz operating system at the same 160 mhz. In this new system, it was possible to receive an incoming call from a fixed Telephone Network. Provided that location of the mobile station was known. A-Netz was wireless but not a cellular network. Therefore A-Netz and B-Netz did not have any function, which permitted and handover or change of base station.
In 1968, in USA, the FCC reconsidered its position on cellular network concept. FCC agreed to allocate a larger vacancy band for more number of mobile phones provided the technology to build a better mobile service be demonstrated. AT&T and Bell labs proposed a cellular system to the FCC with many small, low powered, broadcast towers, each covering a hexagonal "Cell" of a few kilometres in radius. Collectively those cells could cover a very large area. Each tower would use only a few of the total frequencies allocated to the system. As the phones travelled across the area, calls would be passed from tower to tower.
AT&T and Bell labs, other enterprises were also engaged in research in the wireless domain. In 1973 the Martin Cooper of Motorola inversed the first mobile phone handset and made the first phone call from a portable phone to Jeel Angel, his rival in AT&T bell labs. By 1977 , AT&T and bell labs constructed a prototype of public cellular network. In 1982 FCC authorized commercial cellular service for the USA. In 1983, the first American Commercial Analog cellular service AMPS (Advanced Mobile Phone Service) was made commercially available in Chicago. This was the first cellular mobile network in the world.To take advantage of this growing market, each country in Europe developed its own analog mobile system. These cellular system developed by each country in Europe were mutually incompatible. These incompatibilities made the operation of the mobile equipment limited to national boundaries. Also, a mobile subscriber of one network cannot use the same desire in another network in another country.
To cope with these problems Europeans decided to evolve a standard for mobile phone technology. In 1982, the Conference of European Posts and Telegraph (CEPT) formed a study group called the Groups Special Mobile (GSM) to develop a standard for pan-European mobile system. In 1989, GSM responsibility was transferred to the European Telecommunications Standards Units (ETSI) and GSM became a technical committee within ETSI.
In 1990, phase l of the GSM specifications were published Commercial Service of GSM started in 1991. Although standardized in Europe, GSM became popular outside Europe as well. GSM was renamed as Global System For Mobile Communications. In the beginning of 1994, there were 1.3 million subscribers worldwide.
Evolution of Wireless Data
The evolution of wireless technology has also been defined in generation. The first generation (1G) of wireless technology uses the analog technology. It uses FDMA technology for modulation, for example, AMPS in US. The second generation (2G) technology uses digitized technology. It uses a combination of TDMA and FDMA technologies. An example is GSM. In 2G technology, voice is digitized over a circuit. In 1G and 2G networks, data is transacted over circuits. This technology is called Circuit Switched Data or CSD in sort using modems, a data connection is established between the device and the network. This is similar to what happens in dial-up network over analog telephones at home. The next phase in the evolution is 2.5 G. In 2.5 G technology, voice is digitized over a circuit. However, data are in 2.5 G is packetized. 2.5 G uses the same encoding techniques as 2G does. GPRS networks is an example of 2.5 G. Third generation of 3G Wireless Technology makes a Quantum leap from technology point of view. 3G uses spread spectrum techniques for media access and encoding. In 3G networks, boat that and voices uses packets you MTS and CDMA 2000 are example of 3G networks.
While 1G, 2G or 3G were making their marks in Metropolitan Area Wireless Networks (MAN), Wireless Technology has been getting popular in Local Area Networks (LAN), Wireless Technology has been getting popular in Local Area Networks (LAN) and Personal Area Network (PAN) as well. Wireless offers convenience and flexibility. With the success of wireless telephony and messaging services like paging, wireless communication is beginning to be applied to the realm of personal and business computing in the domain of local area networks. Wireless LANs are also being deployed in trains and commercial vehicles. The domain of Wireless Data Networks today comprise a wireless PAN (Bluetooth,Infrared), wireless LAN (IEEE 802.11 family) and Wireless WAN (Wide Area Network), (GSM, GPRS, 3G).
While 1G, 2G or 3G were making their marks in Metropolitan Area Wireless Networks (MAN), Wireless Technology has been getting popular in Local Area Networks (LAN), Wireless Technology has been getting popular in Local Area Networks (LAN) and Personal Area Network (PAN) as well. Wireless offers convenience and flexibility. With the success of wireless telephony and messaging services like paging, wireless communication is beginning to be applied to the realm of personal and business computing in the domain of local area networks. Wireless LANs are also being deployed in trains and commercial vehicles. The domain of Wireless Data Networks today comprise a wireless PAN (Bluetooth,Infrared), wireless LAN (IEEE 802.11 family) and Wireless WAN (Wide Area Network), (GSM, GPRS, 3G).
CELLULAR NETWORK :
A cellular network is a Radio Network made up of radio cells each served by a fixed transmitter, known as a cell site or base station. These cells are used to cover different areas in order to provide radio coverage over a wider area then the area of one cell. Cellular networks are inherently asymmetric with a set of fixed main transceivers each serving a cell and a set of distributed transceivers which provide services to the network's users.
Cellular network offer a number of advantages over alternative solutions :
- Increased Capacity
- Reduced Power Usage
- Better Coverage
A good example of an cellular system is an old taxi driver's radio system where the taxi company will have several transmitters based around a city. We'll use that as an example and assume that each transmitter is handled differently by a different operator.
General Characteristics :
The primary requirement for a network in a cellular concept is a way for each distributed station to distinguish the signal from its own transmitter from the signal from other transmitters. There are two common solutions to this, frequency division multiple access and code division multiple access. FDMA works by using a different frequency for each neighbouring cell. By tuning to the frequency of the chosen cell the distributed station cn avoid the signals from other cells. The principle if CDMA is more complex, but achieves the same result; the distributed transceivers can select one cell and listen to it. Other available methods of multiplexing such as Polarization Division Multiple Access and Time Division Multiple Access cannot be used to separate signals from one cell to the next since the effects of both vary with position and this would make signal separation practically impossible. TDMA, however, is used in combination with either FDMA or CDMA in a number of systems to give multiple channels within the coverage area of one cell.
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