Position of Digital Subscriber Line Among the Internet Connections
In 1995, when Bill Gates presented his operating system Windows’ 95, his aim was “Every house has one computer”. After that time, computer and Internet usage have become prevalent all over the world. Now Bill Gate’s new aim is “every house has a computer connected to Internet continuously. (Çaper, 2001,p.103) Today, people generally use slow dial-up modems to connect to Internet, and users can not benefit from Internet’s many promises. Reaching the data needs some time, but the technological developments need less time to get the useful information. The time passing useless means losing money. Communication technology struggles to find solutions to get the time and money back. Digital Subscriber Line is one of the row materials in that area by using the advantages of the improvements. Developing Internet technology presents DSL, which provides a better connection than Dial-Up, and Cable-Modem, offers a new choice for the user who can not benefit from fiber technology, and DSL market is developing all over the world very fast. Digital Subscriber Line Technology provides better connection than Dial-Up and Cable-Modem technologies. The connection performance is one of the most important parts of the data-transfer. Since 1990’s, there is a rapid improvement at the computer and the Internet technology, and this development offers so many choices to the people. Internet was first realized to connect some specific computers, but now millions of people benefit from the World-Wide-Web.. WWW gives shape to the new century. Sending letters are left nowadays. By using e-mail, a person can share his or her opinions, feelings instantaneously with someone wherever in the world. Internet has removed the borders of countries. A group of people from different nations can talk at Internet and a person can buy something from anywhere on the world.
People face with the speed problem almost at every application of Internet. For some users, searching the World-Wide-Web is so quick. On the other hand, it could take several minutes to reach a simple information. Technology struggles to find solutions to this problem. Developing technology creates Digital Subscriber Line, which uses the known telephone lines. It was first realized to deliver video applications as a rival for Cable-TV systems. This project has not finished yet, but Internet benefit from this technologies potential, and creates the Internet access by using DSL. (Technology Learning Center What is DSL?, 2001,p.1)
The known telephone lines are made from copper, and copper wires can supply data transfer. According to an Internet article “What is DSL?” says:
Digital Subscriber Line, or DSL is a technology that uses regular telephone lines
to transmit a high volume of data at a very high speed. The telephone uses only
part of the frequency available on these copper lines; DSL gets more from them
by splitting the line – using the higher frequencies for data, the lower for voice
and fax. (2001,p.1)
The copper wires can reach very high speeds. The telephone industry has developed various of technologies to transmit data at high rates. ISDN and T1 are the
examples of improvements to supply data transfer over the copper wires. Integrated Services Digital Network provides high speed only when it is needed. It can supply 64 or 128 kilobytes transfer rates and connects to the Internet like a simple dial-up modem. There is no permanent connection, and it has been used in western countries for years. Nowadays, ISDN is considered as an old technology. (Deligöz, 2000,p.97)
T-1 (Tier-1) is a faster connection type, which is first designed to unit multiple voice connections. It has a capacity up to 1,544 megabytes. Today T1 is in use for commercial voice connections. On the other hand, some small businesses and home offices have started using this type of connection for reaching the information. Tier 1 is more costly than most of the other types, so that many user can not afford to use this system. (Clark, 1999, p.97)
Digital Subscriber Line is the most promising technology between the two other types. The switching equipments at the end of the line, affect the rate. Dial-up modems work only with the switches designed for regular voice transfer. As a result of this, dial-up modems can not work over this condition. Different from dial-up, new switches are installed in the central office, and they not only provide known phone calls but also get the full-data carrying capacity which the normal phone calls can not use. (Clark, 1999, p.97)
A personal user generally uses Dial-Up, DSL, or Cable-Modem. According to Clark who is the director of the Advanced Network Architecture Group at MIT, says “It is estimated that in the U.S. ,one home in four now has some kind of access to the Internet”.(1999,p.96)
The common connection type is Dial-Up. Dial-Up modem is a device that converts back and forth streams of data and patterns of audible frequency tones. The data is carried over the lines, which are designed for normal telephone talking. At the end of the line, an Internet Service Provider is needed to connect the user to the world-wide-web. (Clark, 1999, p.96)
The Dial-Up’s performance is limited. Although it is easy to use them and most computers are designed to build with them, the user has to connect with the lines, which
are not produced for data transfer. Furthermore, the connection is not continuous
(Özaygen,1999,p.59) Dial-Up needs different payments to different companies. The national telecom companies cost the time that the user connects to the Internet and the bill is added to the monthly telephone bills. Similarly, the subscriber gives money to the Internet Service Providers. They are independent from the telecom company. Some Internet Service Providers waged the time that the user connects to Internet, and some of them take an amount of money and present an unlimited connection for some time. This could be one month or one year.
There is a race between DSL and Cable-Modem. Clark states in his article "High speed data races home" that telephone and cable companies offer several choices to the consumers. Cable-television companies sell services based on hybrid fiber-coax networks and cable modems as the telephone companies offer broadband Internet service based on ADSL and its known copper lines.(1999,p.99)
ADSL is the most preferred type of DSL applications. The sending and the receiving rates are not equal. The receiving rate is faster than the sending rate. For instance, a sample picture file with a 2MB size could be downloaded in 9,25 minutes by a Dial-Up modem. However, ADSL receives it only in 2,6 seconds.(Yağcı, 2001,p.114).A user using old types of connection types Cable-Modem would be a completely new technology for him or her. Deligöz analyses the cable-modem choice in his article “Dizkonnekt olmayın[Don’t Disconnect!]”. He says that data transfer can only be available where a cable TV network exists, and the substructure is proper. The offering speed might be decreased because of the lines sharing. He also points out that the possibility of proper cable-TV substructure is lower than the other technologies because every cable-TV substructure is not suitable for the data transfer.(2001,p.203)
There are some reasons to prefer DSL. DSL is a more secure service than cable-modem and wireless communication systems. There is a direct connection between the consumer and the telecom company, and Internet connection is permanent. Also, DSL services are 35 times faster than an average dial-up modem.
In Turkey, Dial-Up is the common connection type, but Cable-Modem and DSL services have been growing in last few years. Dial-up connection is available almost everywhere in Turkey. DSL is available only in Istanbul, Izmir, Ankara, and Çanakkale. Moreover Cable-Modem service is available on specific areas where cable TV system exists. . (ADSL ile ilgili sıkça sorulan sorular [Frequently asked questions about ADSL], 2001,p.2)
There are some disadvantages of DSL technology. First of all, as the length of the copper wire increases, the data transfer rate decreases. For instance, if the central office is 2,7 kilometers away from the last user, the maximum rate is 1,568 Megabytes. Otherwise, if the distance increases to 6,5 kilometers, the transfer rate would be 160 Kilobytes. In addition to this, the copper wires could create some troubles like instability and noise due to the bad weather conditions. The equipments used for DSL connection could be more expensive than Dial-Up and Cable. Also, there must be a protocol between the telecom companies and the DSL service providing companies. (Özaygen, 1999,p.58)
DSL offers a choice for the user who can not benefit from the fiber technology. According to Clark: “A single fiber could carry all phone calls in the U.S.” (1999,p.99) Shumate in his article “Broadest broadband” states that fiber optics has a capacity to carry all types of communication signals like telephone, television, videoconferencing, movies, Internet and so on. He also says:
Dedicating one or two lines of fiber to each customer, along with the electronics needed at each end to transmit and receive the optical signals, is very expensive. For a typical suburban home, the one time installation cost – including the cost of all equipment – is currently about $1500….The figure has dropped from about $5000 a decade ago and as to fall as fiber technology advances. But it is still higher in most cases, than the cost of connecting a comparable home with metallic cable. (1999,p.104)
If the distance is optimized in DSL services, soon it would be possible to apply all multimedia over copper lines. There is a need to remember that DSL was first developed to deliver video-applications. Today, videoconference, telecommuting, telemedicine, interactive network games broadcast audio – TV, and online shopping are available over ADSL.( ADSL ile ilgili sıkça sorulan sorular [Frequently asked questions about ADSL],2001,p.1)
DSL market is developing all over the world very fast. As Hawley states in his article “DSL: Broadband by phone” states that Cable-Modem is two year ahead than DSL, but it is estimated that users give up using cable modems in few years, and there is a change for the old copper line.(1999,p.103)
DSL needs some equipments between the line and the computer. One of the most important advantages of DSL is using the copper line both for broadband option, and telephone option. In her article “Çifte teldeki devrim [The revolution at the double line]” Yağcı presents the ‘splitter’ which is used for both telephone and broadband. Telephone calls reach maximum 4 Kbps bandwidth. On the other hand, broadband communication over DSL can reach 9 Mbps. Splitter is a filter that can separate the low and high frequencies. Yağcı emphasizes that splitters must be passive elements, this means, they don’t have to need extra energy to work, so normal telephone calls are done as normal. (2001, p.112)
Today, DSL has created its own market. DSL market develops with the offering of the telephone companies, and with the new products. According to the researches, equipment sales could reach 3 billion dollars in 2005.Also, Telecom services could reach 2 or 3 billion dollars in 2003.There is active more than 180 million in U.S., and 800 million copper wires all over the world. (Yağcı, 2001,p.114) This means there is a very big DSL potential around the globe.
In conclusion, computer and Internet technologies, not only considered as a development of science, but also become a part of life day by day. This will soon change people’s private lives. A person could able to control everything in home from his or her job, on the other hand there would be no offices or today’s school system. It is possible to forget all of these technologies told. There might be completely new developments in a close time. No one can know what technology brings next.
References:
ADSL ile ilgili sıkça sorulan sorular [Frequently asked questions about ADSL] (2001) Available: http://www.telekom.gov.tr
Clark, D.C. (1999, October). High-speed data races home. Scientific American Magazine, p.94-99.
Çaper C. (2001, February) Türkiye ve dünyada teknolojinin 2001 falı [ Technologies 2001 fortune in Turkey and all over the world.] PC Net Magazine, 41, 103
Deligöz, M. (2000, April) Dizkonnekt olmayın! [Don’t disconnect!]. PC NetMagazine, 31, 202-204
Hawley, G.T. (1999,October). DSL: Broadband by phone. Scientific American Magazine, p.102-103.
Özaygen, A. (1999, July). Internet’in geleceğinde yeni bir teknoloji mi? [Is it a new technology at the Internet’s future?]. Bilim&Teknik Magazine, 58-59.
Shumate, P.W. (1999,October). The broadest broadband. Scientific American Magazine, p.104-105.
Technology learning center What is DSL? (2001). Available: http://www.efficient.com
Yağcı, D. (2001, February). Çifte teldeki devrim [The revolution at the double line]. PC Net Magazine, 41, 110-114