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The Development of Cellular Mobile Communication System

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  • 1. THE DEVELOPMENT OF CELLULAR MOBILE COMMUNICATION SYSTEMS By: Yusuf Kurniawan I. Introduction Nowadays, to get in touch with someone who is mobile is not a problem any more. If we could not call him at home we can contact him while he is on the move. Whether he is in a remote place out of reach of the telephone line or just on his way to work, we can still give him a ring. The condition at present differs greatly compared to the 1940s, when the basic cellular concept was developed. 1 The cellular mobile communication system enables the beginning of the wireless communication. Cellular phones or mobile phones are now widely used by a lot of people in all over the world. From year to year the number of mobile phones subscribers increases. For example in the United Kingdom in the end of 1992 there were 1.4 million subscribers, 2 then in 1993 the number became 1.8 million. 3 It is a tremendous figure in the growing number of cellular phones subscribers. Based on the data in the International Institute of Communications (IIC), World Bank, Britain sat in the second position of having the largest cellular phones subscribers after the United States in 1989. 4 According to the poll conducted during 30 March – 2 April 2000 half of all Americans own a cellular phone. 5 1 http://www.wave-guide.org/archives/waveguide_3/cellular-history.html 2 Central Office of Information, Aspects of Britain. (London:1994).p. 7. 3 Central Office of Information in Lax, S. Beyond the Horizon.(Luton:1997).p.20. 4 Central Office of Information, Aspects of Britain. (London:1994).p.8 5 http://www.gallup.com/poll/releases/pr000426.asp
  • 2. 2 The development of the cellular mobile communication system recently is very fast. The network providers of cellular phones are now ubiquitous in every country in all over the world. The rapid development and diffusion of the cellular mobile communication system virtually can not be separated from the previous development of the telecommunication systems, namely electronic telegraphy, radio and telephone. Even though the result of technological development were not planned before, it is important to consider the previous communication devices. Started from the infancy of the telegraph until the maturity of cellular mobile communication, it is a span of inseparable history. This essay tries to reveal the historical and technological development of the cellular mobile communication system since its infancy up to the present time. II. Analysis The development of cellular mobile communication system can be interpreted very broadly. This essay is not going to look at the development in a certain country but in general, since there are several countries take the lead of developing cellular mobile communication system such as the United States and Japan. Let us have a look at a glance to the development of the electric telegraph network. The nature of sending a message through a span of wire electronically inspired Alexander Graham Bell to set up a new telecommunication system called telephone. There are two versions actually who invented the telephone, Alexander Graham Bell or Elisha Gray. Because on the same day, 14 February 1876 they
  • 3. 3 both patented their inventions in Washington. 6 Telephone uses spoken message instead of written as it is used in the telegraph system. Most of all, the invention of the telephone has brought the telecommunication advancement one more step ahead after the telegraphy. The phenomenon of there will be an advanced new technology in communication has actually been started in 1851 when the Thomas Crampton’s Submarine Telegraph Company successfully laid a cable across the sea, from Dover to Calais. 7 The submarine cables which formerly functioned as the electronic telegraph network then were improved to convey telephone signals. And the quality of the cables did gradually improved from copper to coaxial cables and then to optical fibres. Then, by combining the mobile radio system and a certain band, the cellular mobile communication system could be actualised for daily communication. One of the key elements which cause the rapid development of the cellular mobile communication system is the invention of optical fibres. Optical fibres which were invented in 1964 are ‘tiny strands of ultra-pure glass which can carry voice, data, text and images in digital format’. Moreover ‘they also can carry a large amounts of digital information including thousands of telephone calls on pulses of light’. 8 Compared to the predecessor, copper and coaxial cables, optical fibres obviously exceed in all aspects. Optical fibres have many excellence in the voice clearness, amounts of calls they can carry, very low level of interference, speed of pulses and many others that copper and coaxial cables do not have like data and image transfer. The only thing that might be still a consideration for 6 Flichy, P. Dinamics of Modern Communications. (London:1995).p. 82.
  • 4. 4 some cellular phones network providers is probably the cost which is much more expensive compared with coaxial cables. Cellular mobile communication is also called wireless communication since it does not need wire to call. The term ‘wireless’ was actually inspired by Gulielmo Marconi when in 1894 he succeeded to tap out a message in Morse Code. And as a response to the signal, a bell rang at the other end of the room. It was because the signal travelled through the air. Then he called it ‘Wireless’. 9 Thus because Bell’s telephone wires could carry the human voice, then scientists began to search for ways Marconi’s invention could broadcast speech too. And then in 1906, Reginald Fessenden managed to do it by changing sound waves into signals through a process called amplitude modulation (AM). In 1935 Edwin Armstrong, from the United States, introduced FM (frequency modulation) radio waves. Since FM used less power, and smaller, lighter receivers, wireless was on the move. 10 II.1. Cellular Background a. Period of the 1920s – 1950s The development of cellular mobile communication system had actually been commenced in the early of the 1920s (exactly in 1921) when mobile radio communication was used in a vehicle by Detroit Michigan Police Dept. 11 However the channels got overcrowded very quickly since it was operated at a 7 Headrick, D.R. The Invisible Weapon. (New York:1991).p. 15. 8 Central Office of Information, Aspects of Britain. (London:1994).p. 33. 9 http://www.cellularone.com/pages/library/history.html 10 http://www.cellularone.com/pages/library/history.html
  • 5. 5 frequency of 2 MHz. Then the next event of important development also occurred in the United States was the inauguration of the first public mobile telephone system in the US. It had three channels at 150 MHz. 12 But the interference still happened and the equipment still could not solve the problem because the technology at that time did not yet exist to overcome the problems that appeared. Until the 1920s most of the mobile radio communications used Morse-coded on- off keying. 13 In the early development, mobile telephone handsets were still very heavy, bulky and noisy. Because they were operated in the lower frequency part of the VHF band and the range was about ten miles. 14 b. Period of the 1950s – 1960s During this period there was a large increase in bandwidth and switching technology used by the workstations and. For instance in 1956 ’12 wire line channels were added near 450 MHz.’ And the automatic capability was extended to the 450 MHz band in the late of the 1960s. It was called “Improved Mobile Telephone System”, and became the standard for mobile telephone service in the US. 15 c. Period of the 1970s – 1980s This was the period of the more advanced cellular mobile communication system. It was in 1970 when FCC announced a tentative allocation of 75 MHz in the 800 MHz region. 16 And FCC asked some industries to submit their proposals to obtain 11 http://www.wave-guide.org/archives/waveguide_3/cellular-history.html 12 http://www.wave-guide.org/archives/waveguide_3/cellular-history.html 13 Steele, Raymond. Mobile Radio Communications. (London:1992).p. 1 14 Steele, Raymond. Mobile Radio Communications. (London:1992).p. 1 15 http://www.wave-guide.org/archives/waveguide_3/cellular-history.html 16 http://www.wave-guide.org/archives/waveguide_3/cellular-history.html
  • 6. 6 communication goals and as well as to demonstrate feasibility. One monumental event occurred when The Illinois Bell Telephone company was awarded a licence to operate a developmental cellular system in 1977. And between 1974 and 1981 AT&T Bell Labs collaborated with other cellular terminal vendors to develop their cellular phones so that consumers would be able to use their mobile phone on the cellular network. 17 And on October 13, 1983 the first call on a commercial cellular system was built in Chicago. 18 Based on the development of the cellular mobile communication system in the first three periods, the most fundamental problem that still existed was bandwidth –the measure of a communication channel. d. Period of the 1980s – present During this period the development of cellular mobile communication system has been diffusing very rapidly. The big mobile phones manufacturers like Ericsson, Nokia, Siemens, Motorola and NEC began to adopt and applied new technologies in their products and to maximaze the quality of sending and reception in their mobile phones. The development achieved by cellular mobile phone companies during this period showed a great achievement. Especially during the last ten years the development of cellular mobile communication system has been very sophisticated. A cell phone now can be combined with internet. We could be E- mailing from our purses and downloading from our pockets. With WAP (Wireless Application Protocol) phones a mobile phone subscriber can access information in 17 http://www.wave-guide.org/archives/waveguide_3/cellular-history.html 18 http://www.cellularone.com/pages/library/history.html
  • 7. 7 the internet from his mobile phone. More than that, with WAP technology even one can do shopping just from his fingertip. Also in this period, mobile phones subscribers are excited by the emergence of SMS (short message service) that makes them able to send and receive messages to and from other cellular phones. In addition, nowadays there are many ASP (Application Service Protocol) that provide service to send sms, one can send short message to other mobile phones in one country or to all over the world such as www.lycos.co.uk and www.mtnsms.com. Lycos could deliver message to mobile phones in the whole UK with 130 maximum characters long. While using mtnsms one could deliver messages to cellular phones to all over the world with 140 characters long. Even, with mtnsms the subscriber who receives a message could reply it. And the sender would be able to find out the reply message in his mtnsms account. And all of these services are mostly delivered within under ten seconds. These advancements in the technology of cellular mobile communication has enticed more new subscribers to subscribe to cellular phones. Along with the technological development of the cellular mobile phones basically they can be divided into two main categories namely analogue and digital cellular technologies. Each category has its own types. For example in analogue we have like AMPS (Advanced Mobile Phone System). It was developed by Bell Labs in the 1970s and first used commercially in the United States in 1983. It operates in the 800 MHz band and became the world’s largest cellular standard. 19 However, after the 1980s there are more and more cellular 19 http://www.privateline.com/PCS/wirelesstable.htm
  • 8. 8 mobile providers began to shift to digital system. And GSM (Global System for Mobile) is considered the first digital cellular system. 20 GSM is a digital communication technology used by some carriers to provide PCS service. And the other technologies besides GSM and AMPS are CDMA (Code Division Multiple Access) and TDMA (Time Division Multiple Access). II.2 The Basic Principles of Cellular Mobile Phone System The principle used in cellular is called ‘frequency reuse’. 21 It is aimed to increase the service to mobile phone’s subscribers. What is meant by frequently reuse is using low powered mobiles and radio equipment in each site of cells, so that it enables the same radio frequency to be reused in different cells. And it can multiply the calling capacity without causing interference. It is greatly different from the earlier mobile systems which used a high powered, centrally located transmitter. And the frequency used by the mobile phones were not reused over a wide area. 22 All analogue and digital mobiles use a network of base stations and antennas to cover a large area. If it is seen on a diagram the small place which is covered by each base station appears like a cell in a honeycomb. That’s why it is called cellular. The size of the cell varies from sixth tenths of a mile to thirty miles in radius for cellular (1km to 50km). 23 In each cell was built radio base station to handle the incoming signals from other cells. 20 http://www.comms.eee.strath.ac.uk/~gozalvez/gsm/gsm.html 21 http://www.privateline.com/Cellbasics/Cellbasics.html 22 http://www.privateline.com/Cellbasics/Cellbasics.html 23 http://www.privateline.com/PCS/HowPCS works.htm
  • 9. 9 The Ericsson diagram below shows the macrocells, microcells and piccocells work. Slow-moving subscribers such as those who are walking are handled within microcells. While fast-moving subscribers for instance those who are driving or on the public transports are handled within the macrocells. Piccocells are to maintain subsribers of cellular phones who are in a building or in a closed place. The advancement in dividing cells into several kinds has developed the quality of receiving and sending voice. Figure 1: Ericksson Diagram of macrocells, microcells and piccocells (http://www.privateline.com/PCS/HowPCSworks.htm) Figure 2: Cells
  • 10. 10 (http://www.privateline.com/PCS/HowPCSworks.htm) The cells, geographical area where mobile radio communications in cellular radio happen between a fixed base station (BS) and a number of roaming mobile stations (MSs). Figure 3 (http://www.privateline.com/Cellbasics/Cellbasics.html) The picture above shows how wireless technology work. Cell phones use low- energy FM radio waves to transmit voice to the nearest antenna (in a cell) with the local phone network. Then the call will go through either a regular phone line or by radio signal to another cell phone, depending on whom we are calling. This technology uses individual radio frequencies by dividing service areas into different geographic zones. And these zones are called cells. Cells here can be as small as Leeds University library or as large as London City. Usually there are more cells in cities than in rural areas, because there are more people in cities than
  • 11. 11 in rural areas. So, more people, more cells. And each has its own computer, transmitter, receiver and directional antenna which are linked to MTSO or Mobile Telephone Switching Offices. 24 The power of the radio equipment in the base station is fixed so that it covers only the particular cell. When a cellular phone is switched on, the computer at the nearest base station senses its presence within the cell and then the phone can transmit and receive messages from that position. 25 When a cell phone’ subscriber moves from one place to another, his/her call is handed off by MTSO to the next cell site. II.3 Analogue vs Digital Cellular Phones Cellular telephone systems can be ‘analogue’ or ‘digital’. Older systems like AMPS, TACS, NMT are quot;analoguequot; and newer systems such as GSM and PCS are quot;digitalquot;. 26 The major difference is in how the audio signals, e.g. our voice, is transmitted between the phone and base station. quot;Analoguequot; and quot;digitalquot; refer to this transmission mechanism. Probably just as audio cassettes versus CDs - audio cassettes are analogue and CDs are digital. 27 In either system, the audio at the microphone always starts out as a voltage level that varies continuously over time. High frequencies (high pitch) cause rapid changes and low frequencies cause slow changes. With analogue systems, the audio is modulated directly onto a carrier. It has many similarities with FM radio where the audio signal is translated to the RF signal. With digital systems, the audio is converted to digitised samples at about 8000 samples per second or so. 24 http://www.cellularone.com/library/pages/history.html 25 Central Office of Information, Aspects of Britain. (London:1994).p. 49-50. 26 http://www.iit.edu/~diazrab/cell/analogueDigital.html
  • 12. 12 The digital samples are numbers that represent the time-varying voltage level at specific points in time. These samples (numbers) are now transmitted as 1s and 0s. 28 At the other end, the samples are converted back to voltage levels and quot;smoothed outquot; so that you get about the same audio signal. Some maybe lost, but it may be unnoticeable - depending on how it is done. With analogue transmissions, interference (RF noise or some other anomaly that affects the transmitted signal) gets translated directly into the recovered signal - there is no quot;checkquot; that the signal makes sense. The neat thing about digital is that the 1s and 0s can not be easily confused or distorted during transmission, plus extra data is typically included in the transmission to help detect and correct any errors. 29 Digital technology offers better quality of sound, service and more security for the customers and the capability to support services of the next generation. 30 Moreover, digital is more efficient in terms of its achievement in the network. An operator could fit more information into each transmission. So, no wonder if there are many cellular phones’ providers are converting their systems to digital now. II.4 Cellular Equipment There are three types of cellular handset or cellular phone, namely the car-phone or mobile, the transportable and hand-portable. 31 The car-phone or mobile is fitted into a vehicle and receives its power supply directly from the vehicle’s battery. It is hands-free since it is voice-activated. This 27 Communication and Technology lecture, December 2000. 28 Technology and Communication lecture, December 2000. 29 http://www.iit.edu/~diazrab/cell/analogueDigital.html 30 http://www.wirelessadvisor.com/analog-cellular.cfm 31 Central Office of Information, Aspects of Britain. (London:1994).p. 53.
  • 13. 13 enables a caller to use it without holding the handset. However, this device can only be used in the vehicle. The transportable phone is the same with the car-phone but it is designed as an integral unit. It is equipped with detachable battery so that it can be used outside the vehicle. However, it has a lower output if it is used outside the vehicle. Hand-portables are the lightest cellular phones because they are equipped with battery that is integrated with the handset. And the battery is rechargeable. Therefore, the hand-portables cellular phones can be used inside or outside a vehicle. Their power output is lower than the car-phones or transportable, so that they can work best where network coverage is good, like in cities or other built-up areas. 32 III. Conclusion Based on the analysis, it can be concluded that: - The problem of the previous technology of cellular mobile communication system was the limited bandwidth. Because bandwidth allows information to move effortlessly and transparently to where it is needed. The greater the bandwidth, the richer the information we can move. - Wireless technology has come along way. And it will go further. With increased competition, lower rates, smaller phones and larger coverage areas, wireless service will challenge traditional phone service for our business. 32 Central Office of Information, Aspects of Britain. (London:1994).p.53
  • 14. 14 - The invention of cellular mobile communications system has boosted the development of the ‘wireless technology’. People can get connected any time and any where. - The combination of cellular phone and internet enable the cellular mobile communication system maximaze its function as a wireless communication device. Moreover with the more advanced technological development, the cost of communication through cellular phones can be reduced and the size of the hand set gets smaller, lighter and rich in features. What’s more the coverage area becomes wider.
  • 15. 15 REFERENCES Flichy, Patricia (1995), Dynamics of Modern Communication, London: SAGE Publications Ltd. Headrick, Daniel R. (1991) The Invisible Weapon: Telecommunications and International Politics 1851-1945, New York: Oxford University Press. Lax, Stephen (1997), Beyond the Horizon, Luton: University of Luton Press. McLernon (2000), Technology and Communications Lecture. Lectured on December 2000. Reference Services, Central Office of Information (1994), Aspects of Britain: Telecommunications, London: HMSO Publications Centre. Steele, Raymond (1992), Mobile Radio Communications (Ed). London: Pentech Press Publishers. http://www.wave-guide.org/archives/waveguide_3/cellular-history.html. Accessed on 05/12/00. http://www.privateline.com/PCS/HowPCSworks.htm. Accessed on 05/12/00. http://www.privateline.com/PCS/wirelesstable.htm. Accessed on 05/12/00. http://www.fcc.gov/wtb/cellular/celfctsh.html. Accessed on 21/11/00. http://www.dailynews.yahoo.com/h/zd/20001124/tc/bandwidth_is_a_blessing_1.h tm. Accessed on 26/11/00. http://www.cellularone.com/pages/library/history/html. Accessed on 20/12/00. http://www.privateline.com/Cellbasics/Cellbasics.html. Accessed on 20/12/00. http://www.comms.eee.strath.ac.uk/~gozalvez/gsm/gsm.html. Accessed on 06/12/00. http://www.gallup.com/poll/releases/pr000426.asp. Accessed on 19/12/00. http://www.wirelessadvisor.com/Glossary.cfm. Accessed on 23/12/00. http://www.wirelessadvisor.com/analogue-cellular.cfm. Accessed on 23/12/00.