Running head: BROADBAND TECHNOLOGIES: DSL AND CABLE
Broadband Technologies: DSL= and Cable
Broadband Technologies: DSL= and Cable
Consumers desirous of broadband Internet access have several choices, but the main competitors in this market are Digital Subscriber Line – also known as DSL – from their local telephone company and ca= ble broadband from their local cable television company. Bombarded with commerc= ials touting both technologies, questions arise for consumers as to which techno= logy to choose. I intend to examine the technologies, advantages, and disadvanta= ges of both DSL and cable broadband technologies.
Competition between the telephone and cable companies to bec= ome a consumer’s sole provider of information technologies has an interesti= ng history. Asymmetrical Digital Subscriber Line – or ADSL – was an attempt by the telephone companies to provide Video on Demand – or VO= D. “Video on Demand was expected to be the telephone company’s way= of competing with cable television providers, and ADSL was the technology to m= ake it possible” (SYIX.COM, 200= 1). Although Video on Demand never materialized as a viable medium for video co= ntent, the ADSL technology, with higher download speeds than upload speeds, proved= to be an excellent medium for Internet traffic.
Asymmetrical Digital Subscriber Line technology allowed the telephone company to provide high-speed Internet access to consumers over t= he same telephone lines that provide telephone service. This had a large advan= tage in traditional data communications using analog modems over telephone lines= in both speed and the ability to have voice and data communications simultaneously. Whereas analog modems communicated over the meager four kilohertz provided for voice communications, ADSL transceivers access 1.5 megahertz of digital bandwidth over the same set of wires.
Broadband Internet is only available to telephone consumers = when the proper technology is in place at the Central Office, at the consumer’s residence, and when the local loop is prepared to carry the signals. In order to provide DSL service, the telephone company must have a Digital Subscriber Line Access Multiplexer – or DSLAM. This device is= a “mechanism at a phone company’s central location that links many customer DSL connections to a single high-speed ATM line” (Webopedia, n.d.). Without this device, a telephone company cannot provide DSL service to local subscribers= .
The local loop – the set of copper wires running from = the telephone company’s Central Office or neighborhood Remote Terminal to= the customer’s residence – require conditioning before carrying DSL signals. Since the development of the telephone network, on-going improveme= nts in technology and knowledge allowed advances in the quality of voice communications. However, these improvements – notably loading coils – prevent, or block, DSL signals. A telephone company wishing to prov= ide DSL service to local customers must remove all loading coils from the local loop as well as removing all bridge taps – a costly endeavor.
At the customer’s residence, an ADSL Transceiver repla= ces the traditional analog modem, and connects directly to the telephone lines = to provide broadband Internet to the customer’s home network. As well, a filter for analog phones replaces the loading coils removed from the local loop. A typical ADSL customer can expect to receive up to 1.5 megabits per second of download speed from the Internet, although the speed is usually slower.
Like DSL, cable broadband Internet service began with a diff= erent concept. Community Antenna Television – or CATV – began with an innocent attempt to provide broadcast television signals to a mountain community. A large antenna located to provide good reception connected the homes in the mountain community with coaxial cable. This was the birth of t= he cable TV industry, which grew into including a large, complex infrastructure and providing original programming to millions of customers. “Cable television service is available to 95% of all television households in the United States, and about two-thirds of all television households subscribe = to it” (The Museum of Broadcast Communications, n.d.).
Initially, cable TV was a downstream technology – send= ing signals into customer’s homes. However, modifications to the cable TV infrastructure allowed for upstream communications as well. The technology = to provide this ability is the same technology used to provide dozens of telev= ision channels to consumers over one wire – the upstream and downstream sig= nals are analogous to a television channel – one of many – over the wire. It is not difficult to imagine future services provided in the same manner over this wire. At the customer’s residence, a cable modem all= ows access to this data, providing high-speed Internet access, with download sp= eeds approaching five megabits per second, with higher speeds in the near future= .
Both broadband technologies provide high-speed Internet serv= ice, but have unique advantages and disadvantages. Cable broadband Internet is typically faster, and has a newer, faster infrastructure nationwide than the antiquated telephone network used by DSL. However, the telephone network, currently, covers a wider area than the cable network, which translates into access to more potential customers. This advantage to DSL, however, offsets= by the preparation to the local loop and added equipment needed to provide the service. In addition, the speed of DSL signals is distance-dependant. The further the customer is from the Central Office or Remote Terminal, the lon= ger the length of the local loop, and the slower the DSL speed.
One large advantage enjoyed by DSL, one in which few people = recognize, is security. Since the DSL signals operate over the customer’s teleph= one lines, there exists a private, dedicated circuit between the customer and t= he Internet Service Provider. This is not true of cable subscribers. A single feeder line may provide Internet service to up to one thousand customers in= a neighborhood – all of whom connect as if in a giant Local Area Networ= k. Subscribers with the knowledge and software have the ability to monitor the Internet traffic within the feeder line, and perhaps tap into files in their neighbor’s unprotected computer.
It is important to note that not all consumers have a choice= in this matter. Some neighborhoods do not have CATV access, while other neighborhoods’ local loops cannot accept DSL signals. Those with a choice, however, must consider the above advantages and disadvantages caref= ully when considering high-speed Internet access.
References
SYIX.COM (2001). History of DSL. Retrieved July 8, = 2006, from http://www.syix.com/dsl/history.htm
The
Webopedia (n.d.). DSLAM. Retrieved July 8, 2006, fro= m http://www.webopedia.com/TERM/D/DSLAM.html
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