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Handout web technology.doc1


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Handout web technology.doc1

  1. 1. WEEK ONEThe Concept of the InternetHistorical background of the InternetDiscuss Intranet and ExtranetWEEK TWOThe Economics, Social, Political, Educational and Culturalbenefits of InternetWEEK THREEVarious Internet services like: Information search – (on last page) E-commerce E-mail File Transfer Protocol (FTP) Bulletin Board Service Audio-Video Communication Digital Library World Wide Web Telnet and other servicesWEEK FOURUnderstand the basic hardware required for Internetconnectivity: Discuss MODEM and its functionsExplain the Data transfer rate of various MODEMWEEK FIVEExplain the concept of Wireless Transmission andBandwidth 1
  2. 2. Discuss various wireless transmission media: VSAT Radio etcWEEK SIXDiscuss obstacle to effective TransmissionDiscuss the Steps required to connect a PC to the InternetWEEK SEVENDiscuss Problems of Telecommunication infrastructure inNigeria: Technical know-howWEEK EIGHTEconomic factors in Nigeria – Poverty level of the people;level of awarenessWEEK NINEThe government policies on Internet AccessExplain the concept of ISP and the need for itWEEK TENExplain the economic effect of using local or foreign ISPDescribe Domain Name System (DNS) and its spaceWEEK ELEVENExplain how to name servers in the DNSRevisionWEEK TWELVEEXAMINATION 2
  3. 3. LECTURER: MR. M.A. ADEWUSITHE CONCEPT OF THE INTERNETInternet can be termed as the interconnection of the variety of networks and computers.Internet makes use of the internet protocol and the transmission Control protocol. Internetopened the doors of communication between the various stations. Internet facilitatesstoring and transmission of large volumes of data. The internet is one of the mostpowerful communication tools today.In the 1990’s internet gained popularity in the masses. People started becoming aware ofthe uses of internet. Internet helped the people to organize their information and files in asystematic order. Various researches were conducted on internet. Gopher was the firstfrequently used hypertext interface.In 1991, a network based implementation with respect to the hypertext was made. Thetechnology was inspired by many people. With the advent of the World Wide Web searchengine the popularity of internet grew on an extensive scale. Today, the usage of internetis seen in science, commerce and nearly all the fieldsThere are various ways and means to access the internet. With the advancement intechnology people can now access internet services through their cell phones, playstations and various gadgets. There are large numbers of internet service providers aswell.With the development and the wide spread application of internet electronic mail peoplefrom all across the globe come together and communication has become much easier thanever before. Messages, in the form of Emails could be send in at any corner of the worldwithin fractions of seconds. Emails also facilitated mass communication (one sendermany receivers). 3
  4. 4. Emails, video conferencing, live telecast, music, news, e-commerce are some of theservices made available due to internet. Entertainment has taken new dimensions withthe increase of internet and all we see its a continuous development and transformation.THE WEB2.0 CONCEPT"Web 2.0" refers to what is perceived as a second generation of web development andweb design. It is characterized as facilitating communication, information sharing,interoperability, User-centered design[1] and collaboration on the World Wide Web. It hasled to the development and evolution of web-based communities, hosted services, andweb applications. Examples include social-networking sites, video-sharing sites, wikis,blogs, mashups and folksonomies.The term "Web 2.0" was coined by Darcy DiNucci in 1999. In her article "FragmentedFuture," she writes[2]The Web we know now, which loads into a browser window in essentially staticscreenfuls, is only an embryo of the Web to come. The first glimmerings of Web 2.0 arebeginning to appear, and we are just starting to see how that embryo might develop. ...The Web will be understood not as screenfuls of text and graphics but as a transportmechanism, the ether through which interactivity happens. It will [...] appear on yourcomputer screen, [...] on your TV set [...] your car dashboard [...] your cell phone [...]hand-held game machines [...] and maybe even your microwave.Her arguments about Web 2.0 are nascent yet hint at the meaning that is associated withit today.The term is now closely associated with Tim OReilly because of the OReilly MediaWeb 2.0 conference in 2004.[3][4] Although the term suggests a new version of the WorldWide Web, it does not refer to an update to any technical specifications, but rather tocumulative changes in the ways software developers and end-users utilize the Web.According to Tim OReilly:Web 2.0 is the business revolution in the computer industry caused by the move to theInternet as a platform, and an attempt to understand the rules for success on that newplatform.[5] 4
  5. 5. However, whether it is qualitatively different from prior web technologies has beenchallenged. For example, World Wide Web inventor Tim Berners-Lee called the term a"piece of jargon"[6].HISTORICAL BACKGROUNG OF THE INTERNET1950As early as 1950 work began on the defense system know as the Semi-AutomaticGround Environment, or SAGE. This defense system was thought to be required toprotect the US mainland from the new Soviet long range bombers and missile carrierssuch as the Tupolev. IBM, MIT and Bell Labs all worked together to build the SAGEcontinental air defense network that became operational in 1959.SAGE became the most advanced network in the world at the time of its creation andconsisted of early warning radar systems on land, sea, and even air courtesy of AWACSplanes. The network technology lead to more advanced systems and protocols that wouldone day become the Internet, as well as common hardware items such as the mouse,magnetic memory (tape), computer graphics, and the modem.1957In 1957 the USSR launched the first earth-orbiting artificial satellite and kicked off thespace race in a big way. The United States, suddenly fearful of Russian space platformsarmed with nuclear weapons, needed an agency designed to combat this menace. ARPA,or Advanced Research Projects Agency, was founded in 1958 and was given the missionof making the US the leader in science and technology. In 1972 ARPA was renamed theDefense Advanced Research Projects Agency (DARPA). As of 1996 the agency is onceagain called ARPA. 5
  6. 6. ARPA hired J.C.R. Licklider in 1962 to become the Director of their InformationProcessing Techniques Office (IPTO). Licklider’s works eventually lead to the field ofinteractive computing, and is the foundation for the field of Computer Science in general.Lickliders work with computer timesharing helped usher in the practical use of thecomputer network.1962 – Rise of the Modem and the Conceptual InternetAT&T released the first commercially available modem, the Bell 103. The modem wasthe first with full-duplex transmission capability and had a speed of 300 bits per second.The first real conceptual plan of the Internet was being seen in a series of memos releasedby J.C.R Licklider where he referred to a “Galactic Network” that connected all users anddata in the world. These memos grew from his first paper on the subject Man-ComputerSymbiosis released in 1960, although this early work covered human interaction withcomputers and less about human to human communication. In 1962 the aptly named On-Line Man Computer Communications was released and dealt with the concept of socialinteraction through computer networks.Birth of the World Wide Web1992 – ISOCFounded in 1992, The Internet Society (ISOC) is a non-profit organization that assists inthe development of Internet education, policy and standards. The organization has officesin the U.S and Switzerland and works toward an Internet evolution that will benefit theentire world.ISOC is the home of organizations responsible for Internet infrastructure standards, theInternet Engineering Task Force, and the Internet Architecture Board (IAB). ISOC is alsoa clearinghouse for Internet education and information and a facilitator for Internetactivities all over the world. ISOC has run network training programs for developingcountries and assisted in the connecting of almost every country to the Internet. 6
  7. 7. 1994 - The Web Browser is BornJim Clark and Mark Andreessen founded Mosaic Communications in 1994. Andreessenhad been the leader of a software project at the University of Illinois called Mosaic, thefist publically available web browser. Jim and Mark changed the name of MosaicCommunications to Netscape Communications and their web browser was soon releasedto a frantically growing market.Netscape was the largest browser firm in the world very quickly and dominated themarket. Software releases seemed to come out monthly if not faster and it was theseNetscape offerings that lead to the term “internet time”. Business was moving fastereveryday. By 1995 Netscape had an 80% market share.1995 - Windows 95 and the Browser WarsWindows 95 was released by Microsoft and took the world by storm. The software giantsolidified its OS presence and began to make its way into homes across the world. A littleknow program included with the OS was Internet Explorer, a web browser. Microsoftwanted to challenge Netscape’s dominance in the browser market, and had the OSplatform to do it with. Netscape pushed the boundaries of browser technology and madetechnological leaps forward on an almost daily basis. Netscape was considered the mostadvanced browser available, and Microsoft had years of catching up to do. One keydifference however was Internet Explorer was free and Netscape was not. This wasdifficult to overcome but Netscape pushed forward in what was now being called TheBrowser Wars.Although the term Browser Wars generally refers to the competition in the marketplaceof the various web browsers in the early and mid 90’s it is most commonly used inreference to Internet Explorer and Netscape Navigator. Microsoft eventually capturedNetscape’s market share, and Netscape Navigator ceased to be. Firefox is now theprimary browser competitor to Internet Explorer.1998 – ICANN is Formed 7
  8. 8. ICANN is the Internet Corporation for Assigned Names and Numbers and is a not-for-profit public benefit corporation. ICANN helps coordinate the unique identifiers evercomputer needs to be able to communicate via the Internet. It is by these identifierscomputers can find each other, and without them no communication would be possible.ICAAN is dedicated to keeping the Internet the Internet secure, stable, and interoperable.1999 – Y2K LoomsY2K was short for “the year 2000 software problem” and was also called TheMillennium Bug. The problem has been the subject of many books and news reports, andwas discussed by Usenet users as early as 1985.The heart of the problem was that it was thought that computer programs would produceerroneous information or simply stop working because they stored years using only twodigits. This would mean the year 200 would be represented with 00 and appear to be theyear 1900 to the computer.Government committees were set up to drive contingency plans around the Y2K issuethat would help mitigate damages caused to crucial infrastructure such as utilities,telecommunication, banking and more. Although the failing of military systems wasdiscussed in public forums, the danger there was minimal as the closed systems were allY2K compliant. Public fears of the Y2K “disaster” grew as the date approached.Although there was no Y2K disaster either due to concerted efforts or simply becausethere never was a great danger, there were benefits to the issue such as the proliferationof data back up systems and power contingency systems that protect businesses today.One of the few Y2K incidents was the US timekeeper (USNO) reported the new year as19100 on 01/01/2002 8
  9. 9. 2001 – HDTV over an IP NetworkLevel 3 Communications Inc and the University of Southern California successfullydemonstrate the first transmission of uncompressed real-time gigabit high-definitiontelevision over an Internet Protocol optic network. This demonstration proved thetechnology they were using would support high speed data steaming without packetdifferentiation. Without the need of data packets, HDTV anywhere begins to bediscussed.INTRANET AND EXTRANETIntroductionA key requirement in todays business environment is the ability to communicate moreeffectively, both internally with your employees and externally with your trading partnersand customers.An intranet is a private - internal - business network that enables your employees to shareinformation, collaborate, and improve communications.An extranet enables your business to communicate and collaborate more effectively withselected business partners, suppliers and customers. An extranet can play an importantrole in enhancing business relationships and improving supply chain management.An intranet is a business own private website. It is a private business network that usesthe same underlying structure and network protocols as the internet and is protected fromunauthorised users by a firewall. 9
  10. 10. Intranets enhance existing communication between employees, and provide a commonknowledge base and storage area for everyone in your business. They also provide userswith easy access to company data, systems and email from their desktops.Because intranets are secure and easily accessible via the internet, they enable staff to dowork from any location simply by using a web browser. This can help small businesses tobe flexible and control office overheads by allowing employees to work from almost anylocation, including their home and customer sites.Other types of intranet are available that merge the regular features of intranets with thoseoften found in software such as Microsoft Office. These are known as online offices orweb offices. Creating a web office will allow you to organise and manage informationand share documents and calendars using a familiar web browser function, which isaccessible from anywhere in the world.Types of content found on intranets: • administrative - calendars, emergency procedures, meeting room bookings, procedure manuals and membership of internal committees and groups • corporate - business plans, client/customer lists, document templates, branding guidelines, mission statements, press coverage and staff newsletters • financial - annual reports and organisational performance • IT - virus alerts, tips on dealing with problems with hardware, software and networks, policies on corporate use of email and internet access and a list of online training courses and support • marketing - competitive intelligence, with links to competitor websites, corporate brochures, latest marketing initiatives, press releases, presentations • human resources - appraisal procedures and schedules, employee policies, expenses forms and annual leave requests, staff discount schemes, new vacancies • individual projects - current project details, team contact information, project management information, project documents, time and expense reporting 10
  11. 11. • external information resources - route planning and mapping sites, industry organisations, research sites and search engines.Benefits of intranets and extranetsYour organization’s efficiency can be improved by using your intranet for: • publishing - delivering information and business news as directories and web documents • document management - viewing, printing and working collaboratively on office documents such as spreadsheets • training - accessing and delivering various types of e-learning to the users desktop • workflow - automating a range of administrative processes • front-end to corporate systems - providing a common interface to corporate databases and business information systems • email - integrating intranet content with email services so that information can be distributed effectivelyThe main benefits of an intranet are: • better internal communications - corporate information can be stored centrally and accessed at any time • sharing of resources and best practice - a virtual community can be created to facilitate information sharing and collaborative working • improved customer service - better access to accurate and consistent information by your staff leads to enhanced levels of customer service • reduction in paperwork - forms can be accessed and completed on the desktop, and then forwarded as appropriate for approval, without ever having to be printed out, and with the benefit of an audit trail 11
  12. 12. It is a good idea to give your intranet a different image and structure from your customer-facing website. This will help to give your internal communications their own identityand prevent employees confusing internal and external information.BENEFITS OF INTERNET IN RELATION TO:ECONOMICS: The most often cited reasons for communities establishing their own local access networks are for reasons of economic development and the requirement for local businesses to have high-speed Internet services. The system requirements were that it must provide broadband virtual private networks (VPN) and high-speed Internet access for municipal facilities, emergency and public services, businesses and industrial spaces.One of the more recent studies on the economic impact of mass market broadband wasconducted on a range of communities across the United States comparing indicators ofeconomic activity that included employment wages and industry mix (Lehr, Osorio,Gillett and Sirbu, 2004). In those U.S. communities where broadband had been deployedsince December 1999, the researchers found that between 1998 and 2002, thesecommunities experienced more rapid growth in employment, number of businessesoverall, and businesses in IT- intensive sectors.As noted by the authors, “… the early results presented here suggest that the assumed(and oft-touted) economic impacts of broadband are both real and measurable.”[7]The major reason that access to high-speed Internet access is believed to benefit localcommunities, particularly in rural areas, is the impact that it has on increasing thecompetitiveness of businesses by increasing productivity, extending their market reachand reducing costs. Until recently, there has been little research done on attempting toanalyse and document the underlying reasons why businesses are positively impacted byhigh-speed Internet access. There are two studies, one from Cornwall, England and theother from British Columbia, Canada, which have shown remarkably similar results. 12
  13. 13. Cornwall is a relatively isolated area that is provided with high-speed Internet access byactnow, a public-private partnership that was established in 2002 by Cornwall Enterpriseto promote economic development in the region. In April 2005, an online survey ofcompanies that were served by actnow was undertaken. The main findings of the studywere:“Their answers suggest that broadband is generally benefiting enterprises, individuals,the Cornish economy, society and the natural environment by, for example, extendingmarket reach and impact, making organisational working practices more efficient,enabling staff to work flexibly, and substituting travel and meetings with electroniccommunication. In particular: • Over 94% of respondents report positive overall impacts from broadband, with 68% stating that they are highly positive. • A large majority of respondents feel that broadband has positive impacts on business performance (91%), relationships with customers (87%), and the job satisfaction and skills of staff (74%). • 90% of respondents expect to get continued benefits – and 45% considerable benefits - from broadband.” [8]The Peace River and South Silmilkameen regions are located in remote parts of BritishColumbia, Canada. The area is served by the Peace Region Internet Society which is anot for profit organisation established in 1994 to provide affordable access to the Internetfor individuals, businesses, and organizations in the Peace Region of Northern BritishColumbia. In 2005, an online survey of customers was undertaken to measure theeconomic impact of high-speed Internet access in these communities. The major findingswere: “For most businesses in the communities we studied, broadband is an important factorin remaining competitive. Broadband allows businesses to be more productive, toidentify and respond to opportunities faster, and to meet the expectations of customers,partners, and suppliers. • Over 80 per cent of business respondents reported that broadband positively affected their businesses. Over 18 per cent stated they could not operate without broadband; • 62 per cent of businesses say productivity has gone up with a majority citing an increase of more than 10 per cent; 13
  14. 14. • Many businesses reported increased revenue and/or decreased costs due to broadband connectivity.”[9]The two studies show a high degree of similarity in the responses with businesses in bothareas demonstrating that high-speed Internet access has positively impacted theirbusinesses, through increased productivity and overall efficiencies. The researchdemonstrates that high-speed Internet connectivity is important to ensure that businessesin rural and remote areas remain competitive and without it, they would be at a severecompetitive disadvantage.POLITICAL: Theoretical Background: Inclusion in or Exclusion from thePolitical System? Some years ago Dick Morris, one of Bill Clintons spin doctors, saw theUnited States on the way from James Madison towards Thomas Jefferson, fromrepresentative democracy to direct democracy, with the Internet serving as a catalyst(Morris 1999). Al Gore and others tried to "re-invent governance" by means of theInternet, thus creating some sort of "new Athenian age" of democracy (Gore 1995).Today such enthusiasm seems somehow exaggerated. The Internet fell short of manyexpectations not only economically. Now we have the chance to take a restrained look atthe Internet to calculate costs and benefits from online communication - even in the fieldof politics. First we want to specify the three levels on which an impact of the Internet inthis field may be considered: • a macro-level approach considers the use of the Internetby states ("e-governance"). • a meso-level approach considers the use of the Internet bypolitical organizations ("virtual parties") • a micro-level approach considers the use of theInternet by individual citizens ("e- democracy") In our presentation we deal only withmicro-level consequences of Internet usage. Our focus is on the individual activitiespeople take to communicate politically. This includes reception of political media as wellas talks about politics and showing of ones own opinion in public (in a demonstration forexample). What are the common assumptions about consequences of internet usage onpolitical communication? The literature provides a first position that ascribes a"mobilizing function" to the Internet (Schwartz 1996; Rheingold 1994, Grossman 1995).This position expects a higher frequency and a higher intensity in politicalcommunication among Internet users than among non-users. It expects also that theInternet may include even those parts of the population who can’t be reached by 14
  15. 15. traditional channels of political communication. The public and scientific discussion is dominated by this "hypothesis of inclusion": The Internet intensifies political communication and thus leads to a growing integration of citizens into the political system. EDUCATIONAL: The internet provides a powerful resource for learning, as well as an efficient means of communication. Its use in education can provide a number of specific learning benefits, including the development of:• independent learning and research skills, such as improved access to subject learning across a wide range of learning areas, as well as in integrated or cross-curricular studies; and• communication and collaboration, such as the ability to use learning technologies to access resources, create resources and communicate with others. Access to resources The internet is a huge repository of learning material. As a result, it significantly expands the resources available to students beyond the standard print materials found in school libraries. It gives students access to the latest reports on government and non-government websites, including research results, scientific and artistic resources in museums and art galleries, and other organisations with information applicable to student learning. At secondary schooling levels, the internet can be used for undertaking reasonably sophisticated research projects. The internet is also a time-efficient tool for a teacher that expands the possibilities for curriculum development. Learning depends on the ability to find relevant and reliable information quickly and easily, and to select, interpret and evaluate that information. Searching for information on the internet can help to develop these skills. Classroom exercises and take-home assessment tasks, where students are required to compare and contrast website content, are ideal for alerting students to the requirements of writing for different audiences, the purpose of particular content, identifying bias and judging accuracy and reliability. Since many sites adopt particular views about issues, the internet is a useful mechanism for 15
  16. 16. developing the skills of distinguishing fact from opinion and exploring subjectivity andobjectivity.Communication and collaborationThe internet is a powerful tool for developing students’ communication and collaborationskills. Above all, the internet is an effective means of building language skills.Through email, chat rooms and discussion groups, students learn the basic principlesof communication in the written form. This gives teachers the opportunity to incorporateinternet-based activities into mainstream literacy programs and bring diversity to theirrepertoires of teaching strategies. For example, website publishing can be a powerfulmeans of generating enthusiasm for literacy units, since most students are motivated bythe prospect of having their work posted on a website for public access.Collaborative projects can be designed to enhance students’ literacy skills, mainlythrough email messaging with their peers from other schools or even other countries.Collaborative projects are also useful for engaging students and providing meaningfullearning experiences. In this way, the internet becomes an effective means of advancingintercultural understanding. Moderated chat rooms and group projects can also providestudents with opportunities for collaborative learning.Numerous protocols govern use of the internet. Learning these protocols and how toadhere to them helps students understand the rule-based society in which they live and totreat others with respect and decency. The internet also contributes to students’ broaderunderstanding of information and communication technologies (ICT) and its centrality tothe information economy and society as a whole.Culture: Two definitions1: High cultureThe best literature, art, music, film that exists. Societies are often ‘defined’ by their high culture.Problem: who decides what is best – are there any timeless rules?2: Culture as lived experienceCulture is the ordinary, everyday social world around us.Is there a single culture?• In the early part of the 20th century people would talk about “national culture” 16
  17. 17. • With the rise of global media and the deregulation of information flows peopleare more likely to talk about “cultures” within a nation based on age, ethnicity, interests,gender.• There are many cultures and an individual may belong to more than one….• A key issue is that some groups may have more “power” than others to effectpeople’s lives...HARDWARE REQUIREMENT FOR INTERNET CONNECTIVITYThe term modem is an acronym of “modulator-demodulator”. In simple words, a modemenables users to connect their computer to internet. It also enables to transmit and receivedata across the internet. It is the key that unlocks doors of the world of the Internet for theuser. The modems can be of various types. They may be hardware, software or controllerless. The most widely used modems are hardware modems. There are mainly three typesof hardware modems. All three types of modems work the same way. However, each hasits advantages and disadvantages. Here, we discuss them…The oldest and simplest type of hardware modems are external modems. In fact, they arethe earliest modems that have been in use for more then 25 years. As the name suggest,they reside outside the main computer. Therefore, they are easy to install, as the computerneed not be opened. They connect to a computers serial port through a cable. On otherhand, the telephone line is plugged in a socket on the modem. Advantage of an externalmodem is that the external modems have their own power supply. The modem can beturned off to break an online connection quickly without powering down the computer.Another advantage is that by having a separate power supply is that it does not drain anypower from the computer. The Main disadvantage is that the external modems are moreexpensive then the internal modems.On other hand, Internal modems come installed in the computer you buy. Internalmodems are integrated into the computer system mostly installed in the motherboard.Hence, do not need any special attention. Internal modems are activated when you run adialer program to access internet. The internal modem can be turned off when you exitthe program. This can be very convenient. The major disadvantage with internal modems 17
  18. 18. is their location. When you want to replace an internal modem you have to go inside thecomputer case to change it. Internal modems usually cost less than external modems, butthe price difference is usually small.The third significant type of hardware modem is the PC Card modem. These modems aremainly designed for portable computers. They come in size of a credit card and could befitted into the PC Card slot on notebook and handheld computers. These modem cards areremovable when the modem is no longer needed. Most notably, except for their size, PCCard modems combine the characteristics of both external and internal modems. The PCcard modems are plugged directly into an external slot in the portable computer. There isno cable requirement like external modems. The only other requirement is the telephoneline connection. The only disadvantage is that running a PC Card modem while theportable computer is operating on battery power drastically decreases the life of yourbatteries. The portable computer need tp power the PC card modems. This is fine unlessthe computer is battery operated.Overall, you may have an external, an internal modem or a PC modem card as per yourrequirements. The modem you choose should be depend upon how your computer isconfigured and your preferences on accessing internet.HistoryNews wire services in 1920s used multiplex equipment that met the definition, but themodem function was incidental to the multiplexing function, so they are not commonlyincluded in the history of modems.Modems grew out of the need to connect teletype machines over ordinary phone linesinstead of more expensive leased lines which had previously been used for current loop-based teleprinters and automated telegraphs. George Stibitz connected a New Hampshireteletype to a computer in New York City by a subscriber telephone line in 1940. 18
  19. 19. Anderson-Jacobsen brand Bell 101 dataset 110 baud RS-232 modem, in original woodchassisMass-produced modems in the United States began as part of the SAGE air-defensesystem in 1958, connecting terminals at various airbases, radar sites, and command-and-control centers to the SAGE director centers scattered around the U.S. and Canada.SAGE modems were described by AT&Ts Bell Labs as conforming to their newlypublished Bell 101 dataset standard. While they ran on dedicated telephone lines, thedevices at each end were no different from commercial acoustically coupled Bell 101,110 baud modems.In the summer of 1960, the name Data-Phone was introduced to replace the earlier termdigital subset. The 202 Data-Phone was a half-duplex asynchronous service that wasmarketed extensively in late 1960. In 1962, the 201A and 201B Data-Phones wereintroduced. They were synchronous modems using two-bit-per-baud phase-shift keying(PSK). The 201A operated half-duplex at 2000 bit/s over normal phone lines, while the201B provided full duplex 2400 bit/s service on four-wire leased lines, the send andreceive channels running on their own set of two wires each.The famous Bell 103A dataset standard was also introduced by Bell Labs in 1962. Itprovided full-duplex service at 300 baud over normal phone lines. Frequency-shift keyingwas used with the call originator transmitting at 1070 or 1270 Hz and the answeringmodem transmitting at 2025 or 2225 Hz. The readily available 103A2 gave an importantboost to the use of remote low-speed terminals such as the KSR33, the ASR33, and theIBM 2741. AT&T reduced modem costs by introducing the originate-only 113D and theanswer-only 113B/C modems.The Carterfone decisionThe Novation CAT acoustically coupled modem 19
  20. 20. For many years, the Bell System (AT&T) maintained a monopoly in the United States onthe use of its phone lines, allowing only Bell-supplied devices to be attached to itsnetwork. Before 1968, AT&T maintained a monopoly on what devices could beelectrically connected to its phone lines. This led to a market for 103A-compatiblemodems that were mechanically connected to the phone, through the handset, known asacoustically coupled modems. Particularly common models from the 1970s were theNovation CAT and the Anderson-Jacobson, spun off from an in-house project at theLawrence Livermore National Laboratory. Hush-a-Phone v. FCC was a seminal ruling inUnited States telecommunications law decided by the DC Circuit Court of Appeals onNovember 8, 1956. The District Court found that it was within the FCCs authority toregulate the terms of use of AT&Ts equipment. Subsequently, the FCC examiner foundthat as long as the device was not physically attached it would not threaten to degeneratethe system. Later, in the Carterfone decision, the FCC passed a rule setting stringentAT&T-designed tests for electronically coupling a device to the phone lines. AT&Tmade these tests complex and expensive, so acoustically coupled modems remainedcommon into the early 1980s.In December 1972, Vadic introduced the VA3400. This device was remarkable because itprovided full duplex operation at 1200 bit/s over the dial network, using methods similarto those of the 103A in that it used different frequency bands for transmit and receive. InNovember 1976, AT&T introduced the 212A modem to compete with Vadic. It wassimilar in design to Vadics model, but used the lower frequency set for transmission. Itwas also possible to use the 212A with a 103A modem at 300 bit/s. According to Vadic,the change in frequency assignments made the 212 intentionally incompatible withacoustic coupling, thereby locking out many potential modem manufacturers. In 1977,Vadic responded with the VA3467 triple modem, an answer-only modem sold tocomputer center operators that supported Vadics 1200-bit/s mode, AT&Ts 212A mode,and 103A operation. 20
  21. 21. The Smartmodem and the rise of BBSesUS Robotics Sportster 14, 400 Fax modem (1994)The next major advance in modems was the Smartmodem, introduced in 1981 by HayesCommunications. The Smartmodem was an otherwise standard 103A 300-bit/s modem,but was attached to a small controller that let the computer send commands to it andenable it to operate the phone line. The command set included instructions for picking upand hanging up the phone, dialing numbers, and answering calls. The basic Hayescommand set remains the basis for computer control of most modern modems.Prior to the Hayes Smartmodem, modems almost universally required a two-stepprocess to activate a connection: first, the user had to manually dial the remote number ona standard phone handset, and then secondly, plug the handset into an acoustic coupler.Hardware add-ons, known simply as dialers, were used in special circumstances, andgenerally operated by emulating someone dialing a handset.With the Smartmodem, the computer could dial the phone directly by sending the modema command, thus eliminating the need for an associated phone for dialing and the needfor an acoustic coupler. The Smartmodem instead plugged directly into the phone line.This greatly simplified setup and operation. Terminal programs that maintained lists ofphone numbers and sent the dialing commands became common.The Smartmodem and its clones also aided the spread of bulletin board systems (BBSs).Modems had previously been typically either the call-only, acoustically coupled modelsused on the client side, or the much more expensive, answer-only models used on theserver side. The Smartmodem could operate in either mode depending on the commandssent from the computer. There was now a low-cost server-side modem on the market, andthe BBSs flourished. 21
  22. 22. Softmodem (dumb modem)Main article: SoftmodemApples GeoPort modems from the second half of the 1990s were similar. Although aclever idea in theory, enabling the creation of more-powerful telephony applications, inpractice the only programs created were simple answering-machine and fax software,hardly more advanced than their physical-world counterparts, and certainly more error-prone and cumbersome. The software was finicky and ate up significant processor time,and no longer functions in current operating system versions.Almost all modern modems also do double-duty as a fax machine as well. Digital faxes,introduced in the 1980s, are simply a particular image format sent over a high-speed(commonly 14.4 kbit/s) modem. Software running on the host computer can convert anyimage into fax-format, which can then be sent using the modem. Such software was atone time an add-on, but since has become largely universal.A PCI Winmodem/Softmodem (on the left) next to a traditional ISA modem (on theright). Notice the less complex circuitry of the modem on the left.A Winmodem or Softmodem is a stripped-down modem that replaces tasks traditionallyhandled in hardware with software. In this case the modem is a simple digital signalprocessor designed to create sounds, or voltage variations, on the telephone line.Softmodems are cheaper than traditional modems, since they have fewer hardwarecomponents. One downside is that the software generating the modem tones is notsimple, and the performance of the computer as a whole often suffers when it is beingused. For online gaming this can be a real concern. Another problem is lack of portabilitysuch that other OSes (such as Linux) may not have an equivalent driver to operate themodem. A Winmodem might not work with a later version of Microsoft Windows, if itsdriver turns out to be incompatible with that later version of the operating system. 22
  23. 23. Narrowband/phone-line dialup modemsA standard modem of today contains two functional parts: an analog section forgenerating the signals and operating the phone, and a digital section for setup andcontrol. This functionality is actually incorporated into a single chip, but the divisionremains in theory. In operation the modem can be in one of two "modes", data mode inwhich data is sent to and from the computer over the phone lines, and command mode inwhich the modem listens to the data from the computer for commands, and carries themout. A typical session consists of powering up the modem (often inside the computeritself) which automatically assumes command mode, then sending it the command fordialing a number. After the connection is established to the remote modem, the modemautomatically goes into data mode, and the user can send and receive data. When the useris finished, the escape sequence, "+++" followed by a pause of about a second, is sent tothe modem to return it to command mode, and the command ATH to hang up the phoneis sent.The commands themselves are typically from the Hayes command set, although that termis somewhat misleading. The original Hayes commands were useful for 300 bit/soperation only, and then extended for their 1200 bit/s modems. Faster speeds requirednew commands, leading to a proliferation of command sets in the early 1990s. Thingsbecame considerably more standardized in the second half of the 1990s, when mostmodems were built from one of a very small number of "chip sets". We call this theHayes command set even today, although it has three or four times the numbers ofcommands as the actual standard. 23
  24. 24. Increasing speeds (V.21 V.22 V.22bis)A 2400 bit/s modem for a laptop.The 300 bit/s modems used frequency-shift keying to send data. In this system the streamof 1s and 0s in computer data is translated into sounds which can be easily sent on thephone lines. In the Bell 103 system the originating modem sends 0s by playing a1070 Hz tone, and 1s at 1270 Hz, with the answering modem putting its 0s on 2025 Hzand 1s on 2225 Hz. These frequencies were chosen carefully, they are in the range thatsuffer minimum distortion on the phone system, and also are not harmonics of each other.In the 1200 bit/s and faster systems, phase-shift keying was used. In this system the twotones for any one side of the connection are sent at the similar frequencies as in the 300bit/s systems, but slightly out of phase. By comparing the phase of the two signals, 1s and0s could be pulled back out, for instance if the signals were 90 degrees out of phase, thisrepresented two digits, "1, 0", at 180 degrees it was "1, 1". In this way each cycle of thesignal represents two digits instead of one. 1200 bit/s modems were, in effect, 600symbols per second modems (600 baud modems) with 2 bits per symbol.Voiceband modems generally remained at 300 and 1200 bit/s (V.21 and V.22) into themid 1980s. A V.22bis 2400-bit/s system similar in concept to the 1200-bit/s Bell 212signalling was introduced in the U.S., and a slightly different one in Europe. By the late1980s, most modems could support all of these standards and 2400-bit/s operation wasbecoming common. 24
  25. 25. For more information on baud rates versus bit rates, see the companion article List ofdevice bandwidths.Increasing speeds (one-way proprietary standards)Many other standards were also introduced for special purposes, commonly using a high-speed channel for receiving, and a lower-speed channel for sending. One typical examplewas used in the French Minitel system, in which the users terminals spent the majority oftheir time receiving information. The modem in the Minitel terminal thus operated at1200 bit/s for reception, and 75 bit/s for sending commands back to the servers.Three U.S. companies became famous for high-speed versions of the same concept.Telebit introduced its Trailblazer modem in 1984, which used a large number of 36 bit/schannels to send data one-way at rates up to 18,432 bit/s. A single additional channel inthe reverse direction allowed the two modems to communicate how much data waswaiting at either end of the link, and the modems could change direction on the fly. TheTrailblazer modems also supported a feature that allowed them to "spoof" the UUCP "g"protocol, commonly used on Unix systems to send e-mail, and thereby speed UUCP upby a tremendous amount. Trailblazers thus became extremely common on Unix systems,and maintained their dominance in this market well into the 1990s.U.S. Robotics (USR) introduced a similar system, known as HST, although this suppliedonly 9600 bit/s (in early versions at least) and provided for a larger backchannel. Ratherthan offer spoofing, USR instead created a large market among Fidonet users by offeringits modems to BBS sysops at a much lower price, resulting in sales to end users whowanted faster file transfers. Hayes was forced to compete, and introduced its own 9600-bit/s standard, Express 96 (also known as "Ping-Pong"), which was generally similar toTelebits PEP. Hayes, however, offered neither protocol spoofing nor sysop discounts,and its high-speed modems remained rare.4800 and 9600 (V.27ter, V.32)Echo cancellation was the next major advance in modem design. Local telephone linesuse the same wires to send and receive, which results in a small amount of the outgoingsignal bouncing back. This signal can confuse the modem. Is the signal it is "hearing" adata transmission from the remote modem, or its own transmission bouncing back? Thiswas why earlier modems split the signal frequencies into answer and originate; each 25
  26. 26. modem simply didnt listen to its own transmitting frequencies. Even with improvementsto the phone system allowing higher speeds, this splitting of available phone signalbandwidth still imposed a half-speed limit on modems.Echo cancellation got around this problem. Measuring the echo delays and magnitudesallowed the modem to tell if the received signal was from itself or the remote modem,and create an equal and opposite signal to cancel its own. Modems were then able to sendat "full speed" in both directions at the same time, leading to the development of 4800and 9600 bit/s modems.Increases in speed have used increasingly complicated communications theory. 1200 and2400 bit/s modems used the phase shift key (PSK) concept. This could transmit two orthree bits per symbol. The next major advance encoded four bits into a combination ofamplitude and phase, known as Quadrature Amplitude Modulation (QAM). Bestvisualized as a constellation diagram, the bits are mapped onto points on a graph with thex (real) and y (quadrature) coordinates transmitted over a single carrier.The new V.27ter and V.32 standards were able to transmit 4 bits per symbol, at a rate of1200 or 2400 baud, giving an effective bit rate of 4800 or 9600 bits per second. Thecarrier frequency was 1650 Hz. For many years, most engineers considered this rate to bethe limit of data communications over telephone networks.Error correction and compressionOperations at these speeds pushed the limits of the phone lines, resulting in high errorrates. This led to the introduction of error-correction systems built into the modems,made most famous with Microcoms MNP systems. A string of MNP standards came outin the 1980s, each increasing the effective data rate by minimizing overhead, from about75% theoretical maximum in MNP 1, to 95% in MNP 4. The new method called MNP 5took this a step further, adding data compression to the system, thereby increasing thedata rate above the modems rating. Generally the user could expect an MNP5 modem totransfer at about 130% the normal data rate of the modem. MNP was later "opened" andbecame popular on a series of 2400-bit/s modems, and ultimately led to the developmentof V.42 and V.42bis ITU standards. V.42 and V.42bis were non-compatible with MNPbut were similar in concept: Error correction and compression. 26
  27. 27. Another common feature of these high-speed modems was the concept of fallback,allowing them to talk to less-capable modems. During the call initiation the modemwould play a series of signals into the line and wait for the remote modem to "answer"them. They would start at high speeds and progressively get slower and slower until theyheard an answer. Thus, two USR modems would be able to connect at 9600 bit/s, but,when a user with a 2400-bit/s modem called in, the USR would "fall back" to thecommon 2400-bit/s speed. This would also happen if a V.32 modem and a HST modemwere connected. Because they used a different standard at 9600 bit/s, they would fallback to their highest commonly supported standard at 2400 bit/s. The same applies toV.32bis and 14400 bit/s HST modem, which would still be able to communicate witheach other at only 2400 bit/s.Breaking the 9.6k barrierIn 1980 Gottfried Ungerboeck from IBM Zurich Research Laboratory applied powerfulchannel coding techniques to search for new ways to increase the speed of modems. Hisresults were astonishing but only conveyed to a few colleagues. Finally in 1982, heagreed to publish what is now a landmark paper in the theory of information coding. Byapplying powerful parity check coding to the bits in each symbol, and mapping theencoded bits into a two dimensional "diamond pattern", Ungerboeck showed that it waspossible to increase the speed by a factor of two with the same error rate. The newtechnique was called "mapping by set partitions" (now known as trellis modulation).Error correcting codes, which encode code words (sets of bits) in such a way that they arefar from each other, so that in case of error they are still closest to the original word (andnot confused with another) can be thought of as analogous to sphere packing or packingpennies on a surface: the greater two bit sequences are from one another, the easier it is tocorrect minor errors.The industry was galvanized into new research and development. More powerful codingtechniques were developed, commercial firms rolled out new product lines, and thestandards organizations rapidly adopted to new technology. The "tipping point" occurredwith the introduction of the SupraFAXModem 14400 in 1991. Rockwell had introduced anew chipset supporting not only V.32 and MNP, but the newer 14, 400 bit/s V.32bis andthe higher-compression V.42bis as well, and even included 9600 bit/s fax capability. 27
  28. 28. Supra, then known primarily for their hard drive systems, used this chipset to build a low-priced 14, 400 bit/s modem which cost the same as a 2400 bit/s modem from a year ortwo earlier (about US$300). The product was a runaway best-seller, and it was monthsbefore the company could keep up with demand.V.32bis was so successful that the older high-speed standards had little to recommendthem. USR fought back with a 16, 800 bit/s version of HST, while AT&T introduced aone-off 19, 200 bit/s method they referred to as V.32ter (also known as V.32 terbo), butneither non-standard modem sold well.V.34 / 28.8k and 33.6kAn ISA modem manufactured to conform to the V.34 protocol.Any interest in these systems was destroyed during the lengthy introduction of the 28,800 bit/s V.34 standard. While waiting, several companies decided to "jump the gun" andintroduced modems they referred to as "V.FAST". In order to guarantee compatibilitywith V.34 modems once the standard was ratified (1994), the manufacturers were forcedto use more "flexible" parts, generally a DSP and microcontroller, as opposed to purpose-designed "modem chips".Today the ITU standard V.34 represents the culmination of the joint efforts. It employsthe most powerful coding techniques including channel encoding and shape encoding.From the mere 4 bits per symbol (9.6 kbit/s), the new standards used the functionalequivalent of 6 to 10 bits per symbol, plus increasing baud rates from 2400 to 3429, tocreate 14.4, 28.8, and 33.6 kbit/s modems. This rate is near the theoretical Shannon limit. 28
  29. 29. When calculated, the Shannon capacity of a narrowband line is Bandwidth * log2(1+ Pu / Pn), with Pu / Pn the signal-to-noise ratio. Narrowband phone lines have abandwidth from 300-3100 Hz, so using Pu / Pn = 10,000: capacity is approximately36 kbit/s.Without the discovery and eventual application of trellis modulation, maximumtelephone rates would have been limited to 3429 baud * 4 bit/symbol == approximately14 kilobits per second using traditional QAM.Using digital lines and PCM (V.90/92)In the late 1990s Rockwell and U.S. Robotics introduced new technology based upon thedigital transmission used in modern telephony networks. The standard digitaltransmission in modern networks is 64 kbit/s but some networks use a part of thebandwidth for remote office signaling (eg to hang up the phone), limiting the effectiverate to 56 kbit/s DS0. This new technology was adopted into ITU standards V.90 and iscommon in modern computers. The 56 kbit/s rate is only possible from the central officeto the user site (downlink) and in the United States, government regulation limits themaximum power output to only 53.3 kbit/s. The uplink (from the user to the centraloffice) still uses V.34 technology at 33.6k.Later in V.92, the digital PCM technique was applied to increase the upload speed to amaximum of 48 kbit/s, but at the expense of download rates. For example a 48 kbit/supstream rate would reduce the downstream as low as 40 kbit/s, due to echo on thetelephone line. To avoid this problem, V.92 modems offer the option to turn off thedigital upstream and instead use a 33.6 kbit/s analog connection, in order to maintain ahigh digital downstream of 50 kbit/s or higher. (See November and October 2000 updateat ) V.92 also adds two other features. The firstis the ability for users who have call waiting to put their dial-up Internet connection onhold for extended periods of time while they answer a call. The second feature is theability to "quick connect" to ones ISP. This is achieved by remembering the analog anddigital characteristics of the telephone line, and using this saved information to reconnectat a fast pace. 29
  30. 30. Using compression to exceed 56kTodays V.42, V.42bis and V.44 standards allow the modem to transmit data faster thanits basic rate would imply. For instance, a 53.3 kbit/s connection with V.44 can transmitup to 53.3*6 == 320 kbit/s using pure text. However, the compression ratio tends to varydue to noise on the line, or due to the transfer of already-compressed files (ZIP files, [2]JPEG images, MP3 audio, MPEG video). At some points the modem will be sendingcompressed files at approximately 50 kbit/s, uncompressed files at 160 kbit/s, and puretext at 320 kbit/s, or any value in between. [3]In such situations a small amount of memory in the modem, a buffer, is used to hold thedata while it is being compressed and sent across the phone line, but in order to preventoverflow of the buffer, it sometimes becomes necessary to tell the computer to pause thedatastream. This is accomplished through hardware flow control using extra lines on themodem–computer connection. The computer is then set to supply the modem at somehigher rate, such as 320 kbit/s, and the modem will tell the computer when to start or stopsending data.Compression by the ISPAs telephone-based 56k modems began losing popularity, some Internet ServiceProviders such as Netzero and Juno started using pre-compression to increase thethroughput & maintain their customer base. As example, the Netscape ISP uses acompression program that squeezes images, text, and other objects at the server, just priorto sending them across the phone line. The server-side compression operates much moreefficiently than the "on-the-fly" compression of V.44-enabled modems. Typically websitetext is compacted to 4% thus increasing effective throughput to approximately 1300kbit/s. The accelerator also pre-compresses Flash executables and images toapproximately 30% and 12%, respectively.The drawback of this approach is a loss in quality, where the graphics become heavilycompacted and smeared, but the speed is dramatically improved such that web pages loadin less than 5 seconds, and the user can manually choose to view the uncompressedimages at any time. The ISPs employing this approach advertise it as "DSL speeds overregular phone lines" or simply "high speed dial-up". 30
  31. 31. FUNCTIONS In addition to converting digital signals into analog signals, the modems carry out many other tasks. Modems minimize the errors that occur while the transmission of signals. They also have the functionality of compressing the data sent via signals. Modems also do the task of regulating the information sent over a network. • Error Correction: In this process the modem checks if the information they receive is undamaged. The modems involved in error correction divide the information into packets called frames. Before sending this information, the modems tag each of the frames with checksums. Checksum is a method of checking redundancy in the data present on the computer. The modems that receive the information, verify if the information matches with checksums, sent by the error-correcting modem. If it fails to match with the checksum, the information is sent back. • Compressing the Data: For compressing the data, it is sent together in many bits. The bits are grouped together by the modem, in order to compress them. • Flow Control: Different modems vary in their speed of sending signals. Thus, it creates problems in receiving the signals if either one of the modems is slow. In the flow control mechanism, the slower modem signals the faster one to pause, by sending a character. When it is ready to catch up with the faster modem, a different character is sent, which in turn resumes the flow of signals.WiFi and WiMaxWireless data modems are used in the WiFi and WiMax standards, operating atmicrowave frequencies.WiFi is principally used in laptops for Internet connections (wireless access point) andwireless application protocol (WAP).Mobile modems and routersModems which use mobile phone lines (GPRS,UMTS,HSPA,EVDO,WiMax,etc.), areknown as Cellular Modems. Cellular modems can be embedded inside a laptop orappliance, or they can be external to it. External cellular modems are datacards and 31
  32. 32. cellular routers. The datacard is a PC card or ExpressCard which slides into aPCMCIA/PC card/ExpressCard slot on a computer. The most famous brand of cellularmodem datacards is the AirCard made by Sierra Wireless. (Many people just refer to allmakes and models as "AirCards", when in fact this is a trademarked brand name.)Nowadays, there are USB cellular modems as well that use a USB port on the laptopinstead of a PC card or ExpressCard slot. A cellular router may or may not have anexternal datacard ("AirCard") that slides into it. Most cellular routers do allow suchdatacards or USB modems, except for the WAAV, Inc. CM3 mobile broadband cellularrouter. Cellular Routers may not be modems per se, but they contain modems or allowmodems to be slid into them. The difference between a cellular router and a cellularmodem is that a cellular router normally allows multiple people to connect to it (since itcan "route"), while the modem is made for one connection.Most of the GSM cellular modems come with an integrated SIM cardholder (i.e, HuaweiE220, Sierra 881, etc.) The CDMA (EVDO) versions do not use SIM cards, but useElectronic Serial Number (ESN) instead.The cost of using a cellular modem varies from country to country. Some carriersimplement "flat rate" plans for unlimited data transfers. Some have caps (or maximumlimits) on the amount of data that can be transferred per month. Other countries have "perMegabyte" or even "per Kilobyte" plans that charge a fixed rate per Megabyte orKilobyte of data downloaded; this tends to add up quickly in todays content-filled world,which is why many people are pushing for flat data rates. See : flat rate.The faster data rates of the newest cellular modem technologies(UMTS,HSPA,EVDO,WiMax) are also considered to be "Broadband Cellular Modems"and compete with other Broadband modems below.DATA RATE TRANSFERThe speed at which a modem can transfer information, usually given in bits per second (bps). The higher the data transfer rate, the faster the modem, but the more it costs. A faster modem can save you money by cutting down on your long-distance charges. Three common speeds for modems are 9,600 bps, 14,400 bps, and 28,800 bps. 32
  33. 33. Modems are distinguished primarily by the maximum data rate they support. Data rates can range from 75 bits per second up to 56000 and beyond. Data from the user (i.e. flowing from the local terminal or computer via the modem to the telephone line) is sometimes at a lower rate than the other direction, on the assumption that the user cannot type more than a few characters per second. Various data compression and error correction algorithms are required to support the highest speeds. Other optional features are auto-dial (auto-call) and auto-answer which allow the computer to initiate and accept calls without human intervention. Most modern modems support a number of different protocols, and two modems, when first connected, will automatically negotiate to find a common protocol (this process may be audible through the modem or computers loudspeakers). Some modem protocols allow the two modems to renegotiate ("retrain") if the initial choice of data rate is too high and gives too many transmission errors. A modem may either be internal (connected to the computers bus) or external ("stand-alone", connected to one of the computers serial ports). The actual speed of transmission in characters per second depends not just the modem-to-modem data rate, but also on the speed with which the processor can transfer data to and from the modem, the kind of compression used and whether the data is compressed by the processor or the modem, the amount of noise on the telephone line (which causes retransmissions), the serial character format (typically 8N1: one start bit, eight data bits, no parity, one stop bit).WIRELESS TRANSMISSION AND BANDWIDTHThe term "wireless" has become a generic and all-encompassing word used to describecommunications in which electromagnetic waves or RF (rather than some form of wire)carry a signal over part or the entire communication path. Common examples of wirelessequipment in use today include: 33
  34. 34. • Professional LMR (Land Mobile Radio) and SMR (Specialized Mobile Radio) typically used by business, industrial and Public Safety entities • Consumer Two Way Radio including FRS (Family Radio Service), GMRS (General Mobile Radio Service) and Citizens band ("CB") radios • The Amateur Radio Service (Ham radio) • Consumer and professional Marine VHF radios • Cellular telephones and pagers: provide connectivity for portable and mobile applications, both personal and business. • Global Positioning System (GPS): allows drivers of cars and trucks, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth. • Cordless computer peripherals: the cordless mouse is a common example; keyboards and printers can also be linked to a computer via wireless. • Cordless telephone sets: these are limited-range devices, not to be confused with cell phones. • Satellite television: allows viewers in almost any location to select from hundreds of channels. • Wireless gaming: new gaming consoles allow players to interact and play in the same game regardless of whether they are playing on different consoles. Players can chat, send text messages as well as record sound and send it to their friends. Controllers also use wireless technology. They do not have any cords but they can send the information from what is being pressed on the controller to the main console which then processes this information and makes it happen in the game. All of these steps are completed in milliseconds.Wireless networking (i.e. the various types of unlicensed 2.4 GHz WiFi devices) is usedto meet many needs. Perhaps the most common use is to connect laptop users who travelfrom location to location. Another common use is for mobile networks that connect viasatellite. A wireless transmission method is a logical choice to network a LAN segmentthat must frequently change locations. The following situations justify the use of wirelesstechnology: • To span a distance beyond the capabilities of typical cabling, 34
  35. 35. • To avoid obstacles such as physical structures, EMI, or RFI, • To provide a backup communications link in case of normal network failure, • To link portable or temporary workstations, • To overcome situations where normal cabling is difficult or financially impractical, or • To remotely connect mobile users or networks.Wireless communication can be via: • radio frequency communication, • microwave communication, for example long-range line-of-sight via highly directional antennas, or short-range communication, or • infrared (IR) short-range communication, for example from remote controls or via IRDA.Applications may involve point-to-point communication, point-to-multipointcommunication, broadcasting, cellular networks and other wireless networks.The term "wireless" should not be confused with the term "cordless", which is generallyused to refer to powered electrical or electronic devices that are able to operate from aportable power source (e.g. a battery pack) without any cable or cord to limit the mobilityof the cordless device through a connection to the mains power supply. Some cordlessdevices, such as cordless telephones, are also wireless in the sense that information istransferred from the cordless telephone to the telephones base unit via some type ofwireless communications link. This has caused some disparity in the usage of the term"cordless", for example in Digital Enhanced Cordless Telecommunications.In the last fifty years, wireless communications industry experienced drastic changesdriven by many technology innovations.Early wireless workDavid E. Hughes, eight years before Hertzs experiments, induced electromagnetic wavesin a signaling system. Hughes transmitted Morse code by an induction apparatus. In1878, Hughess induction transmission method utilized a "clockwork transmitter" totransmit signals. In 1885, T. A. Edison used a vibrator magnet for induction transmission.In 1888, Edison deploys a system of signaling on the Lehigh Valley Railroad. In 1891, 35
  36. 36. Edison obtained the wireless patent for this method using inductance (U.S. Patent465,971).The demonstration of the theory of electromagnetic waves by Heinrich Rudolf Hertz in1888 was important. The theory of electromagnetic waves were predicted from theresearch of James Clerk Maxwell and Michael Faraday. Hertz demonstrated thatelectromagnetic waves could be transmitted and caused to travel through space at straightlines and that they were able to be received by an experimental apparatus. Theexperiments were not followed up by Hertz. The practical applications of the wirelesscommunication and remote control technology were implemented by Nikola Tesla.Bandwidth (Speed)Wireless Network uses Transmitted signal rather then Wire (CAT5e/CAT6). Thereare few parameters that are affecting Wireless Network communication that are notan issue when using Wired Network. The two most important variables are SignalStrength, Signal Stability.Signal Strength is mainly depending on the Distance and the number and nature ofobstructions. Stability is affected by the presence of other signals in the air +temporal changes in the environment. As an example Computer movement andorientation, people movement, electrical appliances “kinking in and out”, and otherinterferences are constantly changing and affecting the signal in a temporal manner.The general results are that Wireless Bandwidth (Speed) and Latency becomes“None Stop” changeable variables.Wireless Bandwidth (or “Speed”) of Wireless depends on what standard in use(802.11b. 802.11g, etc.) and how much of the signal is available for processing. Thesmaller the signal the less bandwidth.- VSATShort for very small aperture terminal, an earthbound station used in satellitecommunications of data, voice and video signals, excluding broadcast television. AVSAT consists of two parts, a transceiver that is placed outdoors in direct line of sight tothe satellite and a device that is placed indoors to interface the transceiver with the endusers communications device, such as a PC. The transceiver receives or sends a signal to 36
  37. 37. a satellite transponder in the sky. The satellite sends and receives signals from a groundstation computer that acts as a hub for the system. Each end user is interconnected withthe hub station via the satellite, forming a star topology. The hub controls the entireoperation of the network. For one end user to communicate with another, eachtransmission has to first go to the hub station that then retransmits it via the satellite to theother end users VSAT. VSAT can handle up to 56 Kbps.- RADIODirect broadcast satellite, WiFi, and mobile phones all use modems to communicate, asdo most other wireless services today. Modern telecommunications and data networksalso make extensive use of radio modems where long distance data links are required.Such systems are an important part of the PSTN, and are also in common use for high-speed computer network links to outlying areas where fibre is not economical.Even where a cable is installed, it is often possible to get better performance or makeother parts of the system simpler by using radio frequencies and modulation techniquesthrough a cable. Coaxial cable has a very large bandwidth, however signal attenuationbecomes a major problem at high data rates if a digital signal is used. By using a modem,a much larger amount of digital data can be transmitted through a single piece of wire.Digital cable television and cable Internet services use radio frequency modems toprovide the increasing bandwidth needs of modern households. Using a modem alsoallows for frequency-division multiple access to be used, making full-duplex digitalcommunication with many users possible using a single wire.Wireless modems come in a variety of types, bandwidths, and speeds. Wireless modemsare often referred to as transparent or smart. They transmit information that is modulatedonto a carrier frequency to allow many simultaneous wireless communication links towork simultaneously on different frequencies.Transparent modems operate in a manner similar to their phone line modem cousins.Typically, they were half duplex, meaning that they could not send and receive data at thesame time. Typically transparent modems are polled in a round robin manner to collectsmall amounts of data from scattered locations that do not have easy access to wired 37
  38. 38. infrastructure. Transparent modems are most commonly used by utility companies fordata collection.Smart modems come with a media access controller inside which prevents random datafrom colliding and resends data that is not correctly received. Smart modems typicallyrequire more bandwidth than transparent modems, and typically achieve higher datarates. The IEEE 802.11 standard defines a short range modulation scheme that is used ona large scale throughout the world.OBSTACLES TO EFFECTIVE TRANSMISSIONWhile a message source may be able to deliver a message through a transmissionmedium, there are many potential obstacles to the message successfully reaching thereceiver the way the sender intends. The potential obstacles that may affect goodcommunication include: • Poor Encoding – This occurs when the message source fails to create the right sensory stimuli to meet the objectives of the message. For instance, in person-to- person communication, verbally phrasing words poorly so the intended communication is not what is actually meant, is the result of poor encoding. Poor encoding is also seen in advertisements that are difficult for the intended audience to understand, such as words or symbols that lack meaning or, worse, have totally different meaning within a certain cultural groups. This often occurs when marketers use the same advertising message across many different countries. Differences due to translation or cultural understanding can result in the message receiver having a different frame of reference for how to interpret words, symbols, sounds, etc. This may lead the message receiver to decode the meaning of the message in a different way than was intended by the message sender. • Poor Decoding – This refers to a message receiver’s error in processing the message so that the meaning given to the received message is not what the source intended. This differs from poor encoding when it is clear, through comparative analysis with other receivers, that a particular receiver perceived a message differently from others and from what the message source intended. Clearly, as we noted above, if the receiver’s frame of reference is different (e.g., meaning of 38
  39. 39. words are different) then decoding problems can occur. More likely, when it comes to marketing promotions, decoding errors occur due to personal or psychological factors, such as not paying attention to a full television advertisement, driving too quickly past a billboard, or allowing one’s mind to wonder while talking to a salesperson. • Medium Failure – Sometimes communication channels break down and end up sending out weak or faltering signals. Other times the wrong medium is used to communicate the message. For instance, trying to educate doctors about a new treatment for heart disease using television commercials that quickly flash highly detailed information is not going to be as effective as presenting this information in a print ad where doctors can take their time evaluating the information. • Communication Noise – Noise in communication occurs when an outside force in someway affects delivery of the message. The most obvious example is when loud sounds block the receiver’s ability to hear a message. Nearly any distraction to the sender or the receiver can lead to communication noise. In advertising, many customers are overwhelmed (i.e., distracted) by the large number of advertisements they encountered each day. Such advertising clutter (i.e., noise) makes it difficult for advertisers to get their message through to desired customers.STEPS REQUIRED TO CONNECT PC TO INTERNETGeneral GuidelinesUse a FirewallThe most important step when setting up a new computer is to install a firewallBEFORE you connect it to the Internet. Whether this is a hardware router/firewall or asoftware firewall it is important that you have immediate protection when you areconnecting to the Internet. This is because the minute you connect your computer to theInternet there will be remote computers or worms scanning large blocks of IP addresseslooking for computers with security holes. When you connect your computer, if one ofthese scans find you, it will be able to infect your computer as you do not have the latestsecurity updates. You may be thinking, what are the chances of my computer gettingscanned with all the millions of computers active on the Internet. The truth is that your 39
  40. 40. chances are extremely high as there are thousands, if not more, computers scanning atany given time. The best scolution is if you have a hardware router/firewall installed..This is because you will be behind that device immediately on turning on your computerand there will be no lapse of time between your connecting to the Internet and beingsecure. If a hardware based firewall is not available then you should use a software basedfirewall. Many of the newer operating systems contain a built-in firewall that you shouldimmediately turn on. If your operating system does not contain a built-in firewall thenyou should download and install a free firewall as there are many available. If you have afriend or another computer with a cd rom burner, download the firewall and burn it onto aCD so that you can install it before you even connect your computer to the Internet. Wehave put together a tutorial on firewalls that you can read by clicking on the link below:Disable services that you do not immediately needDisable any non-essential services or applications that are running on your computerbefore you connect to the Internet. When an operating system is not patched to the latestsecurity updates there are generally a few applications that have security holes in them.By disabling services that you do not immediately need or plan to use you minimize therisk of these security holes being used by a malicious user or piece of software.Download the latest security updatesNow that you have a firewall and non-essential services disabled, it is time to connectyour computer to the Internet and download all the available security updates for youroperating system. By downloading these updates you will ensure that your computer is upto date with all the latest available security patches released for your particular operatingsystem and therefore making it much more difficult for you to get infected with a piece ofmalware.Use an Antivirus SoftwareMany of the programs that will automatically attempt to infect your computer are worms,trojans, and viruses. By using a good and up to date antivirus software you will be able tocatch these programs before they can do much harm. You can find a listing of some freeantivirus programs at the below link: 40
  41. 41. Browse through the various free antivirus programs at the above list and install onebefore you connect to the Internet. Download it from another computer and burn it onto aCD so that it is installed before you connect.Specific Steps for Windows 2000Windows 2000 does not contain a full featured firewall, but does contain a way for you toget limited security until you update the computer and install a true firewall. Windows2000 comes with a feature called TCP filtering that we can use as a temporary measure.To set this up follow these steps: 1. Click on Start, then Settings and then Control Panel to enter the control panel. 2. Double-click on the Network and Dial-up Connections control panel icon. 3. Right-click on the connection icon that is currently being used for Internet access and click on properties. The connection icon is usually the one labeled Local Area Connection 4. Double-click on Internet Protocol (TCP/IP) and then click on the Advanced button. 5. Select the Options tab 6. Double-click on TCP/IP Filtering. 7. Put a checkmark in the box labeled Enable TCP/IP Filtering (All Adapters) and change all the radio dial options to Permit Only. 8. Press the OK button. 9. If it asks to reboot, please do so.After it reboots your computer will now be protected from the majority of attacks fromthe Internet. Now immediately go to and download andinstall all critical updates and service packs available for your operating system. Keepgoing back and visiting this page until all the updates have been installed.Once that is completed install an antivirus software and free firewall, and disable thefiltering we set up previously.Specific Steps for Microsoft Windows XP 41
  42. 42. If you have recently purchased a computer and it came with XP Service Pack 2 installed,then the firewall will be enabled by default and you will not have to do anything butinstall a antivirus software and check for any new updates at the other hand, if this is an older computer, or you are re-installing one, then youshould follow these steps before you connect to the Internet: 1. Log into Windows XP with an administrator account. 2. Enable the Internet Connection Firewall by following the steps found in the following tutorial link: Configuring Windows XP Internet Connection Firewall 3. Once the firewall has been turned immediately go to and download and install all critical updates and service packs available for your operating system. Keep going back and visiting this page until all the updates have been installed. 4. Once that is completed install an antivirus software and free firewall. 5. Disable the built in XP firewall.Specific Steps for MAC OSXMac OSX has a built-in firewall that should be used before connecting to the Internet. Toturn this firewall on follow these steps: 1. Open up the System Preferences 2. Click on the Sharing icon 3. Click on the Firewall tab 4. Click on the Start button 5. Now the screen should show the status of the Firewall as On.Now that the firewall is configured you should connect to the Internet and immediatelycheck for new updates from Apple by following these steps: 1. Choose System Preferences from the Apple Menu. 2. Choose Software Update from the View menu. 3. Click Update Now. 42
  43. 43. 4. Select the items you want to install, then click Install. 5. Enter an Admin user name and password. 6. After the update is complete, restart the computer if necessaryNow install an antivirus software on your computer if one is not already.Specific Steps for Linux/UNIXAlmost all Linux distributions come with a built in firewall which is usually iptables.Make sure that the firewall is starting automatically at boot up and is configured to denyall traffic inbound to your computer except for the services you require like SSH.Unfortunately iptables would require a tutorial all in its own, so I will refer you to thisalready created tutorial:Installing and Configuring iptablesOnce the firewall is configured, go to the respective site for your Linux distribution andimmediately download and install any of the latest security updates that are available.Windows is not the only operating system with security vulnerabilities and it is just asimportant for Linux users to have an up to date operating system.ConclusionAs you can see the most important step that should be done before connecting to theInternet is to install a firewall and block all ports that you do not need open. This willassure us that your computer will not become hacked by many of the worms and bots outon the Internet. Once a firewall is installed, updating your computer and installing anantivirus software are the next steps. Please follow these steps, as if it is not done, yourcomputer will ultimately get compromised and then further proliferate the infection ofothers..PROBLEMS OF TELECOMMUNICATIONInformation technology is continually developing and in the last few years there has been a rapid growth in electronic telecommunications to provide Internet and other network-based services. Interest in using telecommunications to provide services to the public is growing, with a number of pilot services being set up across the 43
  44. 44. country to explore market potential and/or stimulate demand.Administrations across Europe are now using telecommunications technology to provide citizens with information (Hoare, 1998). The British Government, for instance, has issued a directive that 25% of all civil service communications must be on-line by 2002. This is intended to provide savings in paperwork and a streamlined service.An area of possible government assistance is to provide the public with on-line information about welfare benefit entitlement. This may have benefits for all members of society but could be of particular value for retired and older members of the public, many of whom do not always claim their entitlement. It is estimated in the UK, for example, that one million pensioners could be entitled to Income Support that they are not claiming (Benefits Agency, 1998). To provide information to the public, the Benefits Agency produces a website of over 1,000 pages for customers to browse through which can be viewed at Yet while many people are now connected to the Internet, and the EU average is 25 computers connected per thousand people, (Lennon, 1999) the number of older or retired people using it is still quite small. An indication of this is given by the results of the worldwide 10th Georgia Tech web survey (GVU, 1999). The survey, conducted in 1998, received 5,022 responses of which only 2.7% were from people who were 66 years of age and over.This raises the key question of whether older people will be able to benefit from the promise of the connected future, with information available electronically on tap, or whether they will get left behind. This also represents a lost opportunity for suppliers as, according to Oftel (the UK telephone watchdog organisation) and disability campaign groups, A growing grey market containing millions of potential customers is being ignored in the telecoms boom, Dawe (1998).Domain Name SystemThe Domain Name System (DNS) is a hierarchical naming system for computers,services, or any resource connected to the Internet or a private network. It associatesvarious information with domain names assigned to each of the participants. Mostimportantly, it translates domain names meaningful to humans into the numerical (binary)identifiers associated with networking equipment for the purpose of locating andaddressing these devices worldwide. An often-used analogy to explain the Domain Name 44
  45. 45. System is that it serves as the "phone book" for the Internet by translating human-friendlycomputer hostnames into IP addresses. For example, translates to192.0.32.10.The Domain Name System makes it possible to assign domain names to groups ofInternet users in a meaningful way, independent of each users physical location. Becauseof this, World Wide Web (WWW) hyperlinks and Internet contact information canremain consistent and constant even if the current Internet routing arrangements changeor the participant uses a mobile device. Internet domain names are easier to rememberthan IP addresses such as (IPv4) or2001:db8:1f70::999:de8:7648:6e8 (IPv6). People take advantage of this when theyrecite meaningful URLs and e-mail addresses without having to know how the machinewill actually locate them.The Domain Name System distributes the responsibility of assigning domain names andmapping those names to IP addresses by designating authoritative name servers for eachdomain. Authoritative name servers are assigned to be responsible for their particulardomains, and in turn can assign other authoritative name servers for their sub-domains.This mechanism has made the DNS distributed, fault tolerant, and helped avoid the needfor a single central register to be continually consulted and updated.In general, the Domain Name System also stores other types of information, such as thelist of mail servers that accept email for a given Internet domain. By providing aworldwide, distributed keyword-based redirection service, the Domain Name System isan essential component of the functionality of the Internet.Other identifiers such as RFID tags, UPC codes, International characters in emailaddresses and host names, and a variety of other identifiers could all potentially utilizeDNS.[1]The Domain Name System also defines the technical underpinnings of the functionalityof this database service. For this purpose it defines the DNS protocol, a detailedspecification of the data structures and communication exchanges used in DNS, as part ofthe Internet Protocol Suite (TCP/IP).OverviewThe Internet maintains two principal namespaces, the domain name hierarchy and theInternet Protocol (IP) address system.[3] The Domain Name System maintains the domainnamespace and provides translation services between these two namespaces. Internetname servers and a communications protocol, implement the Domain Name System. [4] ADNS name server is a server that stores the DNS records, such as address (A) records,name server (NS) records, and mail exchanger (MX) records for a domain name andresponds with answers to queries against its database. 45
  46. 46. HistoryThe practice of using a name as a humanly more meaningful abstraction of a hostsnumerical address on the network dates back to the ARPANET era. Before the DNS wasinvented in 1983, each computer on the network retrieved a file called HOSTS.TXT froma computer at SRI (now SRI International).[5][6] The HOSTS.TXT file mapped names tonumerical addresses. A hosts file still exists on most modern operating systems, either bydefault or through explicit configuration. Many operating systems use name resolutionlogic that allows the administrator to configure selection priorities for available DNSresolution methods.The rapid growth of the network required a scalable system that recorded a change in ahosts address in one place only. Other hosts would learn about the change dynamicallythrough a notification system, thus completing a globally accessible network of all hostsnames and their associated IP addresses.At the request of Jon Postel, Paul Mockapetris invented the Domain Name System in1983 and wrote the first implementation. The original specifications appeared in RFC882 and RFC 883 which were superseded in November 1987 by RFC 1034[2] and RFC1035.[4] Several additional Request for Comments have proposed various extensions tothe core DNS protocols.In 1984, four Berkeley students—Douglas Terry, Mark Painter, David Riggle andSongnian Zhou—wrote the first UNIX implementation, which was maintained by RalphCampbell thereafter. In 1985, Kevin Dunlap of DEC significantly re-wrote the DNSimplementation and renamed it BIND—Berkeley Internet Name Domain. Mike Karels,Phil Almquist and Paul Vixie have maintained BIND since then. BIND was ported to theWindows NT platform in the early 1990s.BIND was widely distributed, especially on Unix systems, and is the dominant DNSsoftware in use on the Internet. [7] With the heavy use and resulting scrutiny of its open-source code, as well as increasingly more sophisticated attack methods, many securityflaws were discovered in BIND. This contributed to the development of a number ofalternative nameserver and resolver programs. BIND itself was re-written from scratch inversion 9, which has a security record comparable to other modern Internet software.The DNS protocol was developed and defined in the early 1980s and published by theInternet Engineering Task Force. 46
  47. 47. StructureThe domain name spaceThe hierarchical domain name system, organized into zones, each served by a nameserver.The domain name space consists of a tree of domain names. Each node or leaf in the treehas zero or more resource records, which hold information associated with the domainname. The tree sub-divides into zones beginning at the root zone. A DNS zone consists ofa collection of connected nodes authoritatively served by an authoritative nameserver.(Note that a single nameserver can host several zones.)Administrative responsibility over any zone may be divided, thereby creating additionalzones. Authority is said to be delegated for a portion of the old space, usually in form ofsub-domains, to another nameserver and administrative entity. The old zone ceases to beauthoritative for the new zone. 47