Broadband Technologies

Voice Over Internet Protocol

2009-03-08T18:36:00.000-07:00

Voice over Internet Protocol (VoIP), is a technology that allows you to make voice calls using a broadband Internet connection instead of a regular (or analog) phone line. Some VoIP services may only allow you to call other people using the same service, but others may allow you to call anyone who has a telephone number - including local, long distance, mobile, and international numbers. Also, while some VoIP services only work over your computer or a special VoIP phone, other services allow you to use a traditional phone connected to a VoIP adapter.

Frequently Asked Questions

How VoIP / Internet Voice Works
VoIP services convert your voice into a digital signal that travels over the Internet. If you are calling a regular phone number, the signal is converted to a regular telephone signal before it reaches the destination. VoIP can allow you to make a call directly from a computer, a special VoIP phone, or a traditional phone connected to a special adapter. In addition, wireless "hot spots" in locations such as airports, parks, and cafes allow you to connect to the Internet and may enable you to use VoIP service wirelessly.

What Kind of Equipment Do I Need?
A broadband (high speed Internet) connection is required. This can be through a cable modem, or high speed services such as DSL or a local area network. A computer, adaptor, or specialized phone is required.Some VoIP services only work over your computer or a special VoIP phone, while other services allow you to use a traditional phone connected to a VoIP adapter. If you use your computer, you will need some software and an inexpensive microphone. Special VoIP phones plug directly into your broadband connection and operate largely like a traditional telephone. If you use a telephone with a VoIP adapter, you'll be able to dial just as you always have, and the service provider may also provide a dial tone.

Is there a difference between making a Local Call and a Long Distance Call?

Some VoIP providers offer their services for free, normally only for calls to other subscribers to the service. Your VoIP provider may permit you to select an area code different from the area in which you live. It also means that people who call you may incur long distance charges depending on their area code and service.

Some VoIP providers charge for a long distance call to a number outside your calling area, similar to existing, traditional wireline telephone service. Other VoIP providers permit you to call anywhere at a flat rate for a fixed number of minutes.

If I have VoIP service, who can I call?
Depending upon your service, you might be limited only to other subscribers to the service, or you may be able to call anyone who has a telephone number - including local, long distance, mobile, and international numbers. If you are calling someone who has a regular analog phone, that person does not need any special equipment to talk to you. Some VoIP services may allow you to speak with more than one person at a time.

What Are Some Advantages of VoIP?
Some VoIP services offer features and services that are not available with a traditional phone, or are available but only for an additional fee. You may also be able to avoid paying for both a broadband connection and a traditional telephone line.

What Are Some disadvantages of VoIP?
If you're considering replacing your traditional telephone service with VoIP, there are some possible differences:

Some VoIP services don't work during power outages and the service provider may not offer backup power.
Not all VoIP services connect directly to emergency services through 9-1-1. For additional information, seewww.voip911.gov.
VoIP providers may or may not offer directory assistance/white page listings.

Can I use my Computer While I talk on the Phone?
In most cases, yes.

Can I Take My Phone Adapter with me When I Travel?
Some VoIP service providers offer services that can be used wherever a high speed Internet connection available. Using a VoIP service from a new location may impact your ability to connect directly to emergency services through 9-1-1. For additional information, see www.voip911.gov.

Does my Computer Have to be Turned on?
Only if your service requires you to make calls using your computer. All VoIP services require your broadband Internet connection to be active.

How Do I Know If I have a VoIP phone Call?
If you have a special VoIP phone or a regular telephone connected to a VoIP adapter, the phone will ring like a traditional telephone. If your VoIP service requires you to make calls using your computer, the software supplied by your service provider will alert you when you have an incoming call.

Does the FCC Regulate VoIP?
In June 2005 the FCC imposed 911 obligations on providers of “interconnected” VoIP services – VoIP services that allow users generally to make calls to and receive calls from the regular telephone network. You should know, however, that 911 calls using VoIP are handled differently than 911 calls using your regular telephone service. Please see our consumer fact sheet on VoIP and 911 services at www.voip911.gov for complete information on these differences.

In addition, the FCC requires interconnected VoIP providers to comply with the Communications Assistance for Law Enforcement Act of 1994 (CALEA) and to contribute to the Universal Service Fund, which supports communications services in high-cost areas and for income-eligible telephone subscribers.

Aspects of these considerations may change with new developments in internet technology. You should always check with the VoIP service provider you choose to confirm any advantages and limitations to their service.

Telecommunication

2008-11-21T05:16:00.000-08:00

Telecommunication is the assisted transmission of signals over a distance for the purpose ofcommunication. In earlier times, this may have involved the use of smoke signals, drums, semaphore,flags, Morse Code, or heliograph. In modern times, telecommunication typically involves the use of electronic transmitters such as the telephone, television, radio or computer. Early inventors in the field of telecommunication include Alexander Graham Bell, Guglielmo Marconi and John Logie Baird. Telecommunication is an important part of the world economy and the telecommunication industry's contribution was estimated to be $1.2 trillion in 2006.

Etymology

The word telecommunication was adopted from the French word télécommunication. It is a compound of the Greek prefix tele- (τηλε-), meaning 'far off', and the Latin communicare, meaning 'to share'.^[1] The French word télécommunication was coined in 1904 by French engineer and novelist Édouard Estaunié.^[2]

Key concept

Basic elements

A telecommunication system consists of three basic elements:

a transmitter that takes information and converts it to a signal;
a transmission medium that carries the signal; and,
a receiver that receives the signal and converts it back into usable information.

For example, in a radio broadcast the broadcast tower is the transmitter, free space is the transmission medium and the radio is the receiver. Often telecommunication systems are two-way with a single device acting as both a transmitter and receiver or transceiver. For example, amobile phone is a transceiver.^[3]

Telecommunication over a telephone line is called point-to-point communication because it is between one transmitter and one receiver. Telecommunication through radio broadcasts is called broadcast communication because it is between one powerful transmitter and numerous receivers.^[3]

Analogue or digital

Signals can be either analogue or digital. In an analogue signal, the signal is varied continuously with respect to the information. In a digital signal, the information is encoded as a set of discrete values (for example ones and zeros). During transmission the information contained in analogue signals will be degraded by noise. Conversely, unless the noise exceeds a certain threshold, the information contained in digital signals will remain intact. This noise resistance represents a key advantage of digital signals over analogue signals.^[4]

Networks

A network is a collection of transmitters, receivers and transceivers that communicate with each other. Digital networks consist of one or morerouters transmiting information to various users. An analogue network consists of one or more switches that establish a connection between two or more users. For both types of network, repeaters may be necessary to amplify or recreate the signal when it is being transmitted over long distances. This is to combat attenuation that can render the signal indistinguishable from noise.^[5]

Channels

A channel is a division in a transmission medium so that it can be used to send multiple streams of information. For example, a radio station may broadcast at 96.1 MHz while another radio station may broadcast at 94.5 MHz. In this case, the medium has been divided by frequencyand each channel has received a separate frequency to broadcast on. Alternatively, one could allocate each channel a recurring segment of time over which to broadcast—this is known as time-division multiplexing and is sometimes used in digital communication.^[6]^[7]

Modulation can also be used to transmit the information of analogue signals at higher frequencies. This is helpful because low-frequency analogue signals cannot be effectively transmitted over free space. Hence the information from a low-frequency analogue signal must be superimposed on a higher-frequency signal (known as a carrier wave) before transmission. There are several different modulation schemes available to achieve this (two of the most basic being amplitude modulation and frequency modulation). An example of this process is a DJ'svoice being superimposed on a 96 MHz carrier wave using frequency modulation (the voice would then be received on a radio as the channel “96 FM”).^[8]

Society and telecommunication

An antique radio, a Contempra Telephone (Artifact no. 2000 0019) by Northern Electric (Nortel) (Syd Horen, John Tyson, Graham Parson) ca. 1967., a television display system and the first Canadian (Quebec) designed fully electronic digital telephone switching board ca. 1972. on display at the Museum of Science and Technology (Aug 2008).

Telecommunication is an important part of modern society. In 2006, estimates placed the telecommunication industry's revenue at $1.2 trillion or just under 3% of the gross world product (official exchange rate).^[9] There exist several economic,^[10] social^[11]and sovereignistic^[12] impacts.

Altering of Space and Time

Thompson notes how the use of technical media of communication can "alter the spatial and temporal dimensions of social life"^[13] The development of telecommunication technology in the second half of the 19th century was particularly momentous in the altering of social life with characteristics of spatial and temporal aspects being altered. As Thompson argues the advent of telecommunication technologies, such as the telegraph and telephone, resulted in the "uncoupling of space and time" in the sense that concepts of space and time were altered in the communication process. ^[14] This prepared the way for another transformation, which Nowotny describes as: the “discovery of despatialized simultaneity”^[15] revolutionized the experience of simultaneity as it "became detached from the spatial condition of common locality."^[16] With this came the possibility to experience events as simultaneous and changed telecommunication forever.

Economics

Microeconomics

On the microeconomic scale, companies have used telecommunication to help build global empires. This is self-evident in the case of online retailer Amazon.com but, according to academic Edward Lenert, even the conventional retailer Wal-Mart has benefited from better telecommunication infrastructure compared to its competitors.^[17] In cities throughout the world, home owners use their telephones to organize many home services ranging from pizza deliveries to electricians. Even relatively poor communities have been noted to use telecommunication to their advantage. In Bangladesh's Narshingdi district, isolated villagers use cell phones to speak directly to wholesalers and arrange a better price for their goods. In Cote d'Ivoire, coffee growers share mobile phones to follow hourly variations in coffee prices and sell at the best price.^[18]

Macroeconomics

On the macroeconomic scale, Lars-Hendrik Röller and Leonard Waverman suggested a causal link between good telecommunication infrastructure and economic growth.^[19] Few dispute the existence of a correlation although some argue it is wrong to view the relationship as causal.^[20] Because of the economic benefits of good telecommunication infrastructure, there is increasing worry about the inequitable access to telecommunication services amongst various countries of the world—this is known as the digital divide.

Social

Cellular Telephone Industry

In 2000, market research group Ipsos MORI reported that 81% of 15 to 24 year-old SMS users in the United Kingdom had used the service to coordinate social arrangements.^[21] The cellular telephone industry has had significant impact of telecommunications. A 2003 survey by theInternational Telecommunication Union (ITU) revealed that roughly one-third of countries have less than 1 mobile subscription for every 20 people and one-third of countries have less than 1 fixed line subscription for every 20 people. In terms of Internet access, roughly half of all countries have less than 1 in 20 people with Internet access. From this information, as well as educational data, the ITU was able to compile an index that measures the overall ability of citizens to access and use information and communication technologies.^[22] Using this measure, Sweden, Denmark and Iceland received the highest ranking while the African countries Niger, Burkina Faso and Mali received the lowest.^[23]

Sovereignty

Canadian Telecommunications Act

Telecommunications play an essential role in the maintenance of Canada’s identity and sovereignty.^[24] The Canadian Government has even created law to govern the use of telecommunications. Canada's Telecommunications Act and it's policy, which received royal assent on June 23, 1993, prevails over the provisions of any special Act.^[24] Some of its objectives are :

"(a) to facilitate the orderly development throughout Canada of a telecommunications system that serves to safeguard, enrich and strengthen the social and economic fabric of Canada and its regions;...

(e) to promote the use of Canadian transmission facilities for telecommunications within Canada and between Canada and points outside Canada;...

(h) to respond to the economic and social requirements of users of telecommunications services; and

(i) to contribute to the protection of the privacy of persons."^[24]

Canadian Broadcasting Act

Furthermore, Canada's Telecommunications Act references the Broadcasting Act which prescribes that broadcasting has an important role in Canadian sovereignty.^[24]^[25]^[26] In fact, the Canadian broadcasting system is legislated to be owned and controlled by Canadians.^[27] In this case, the Canadian Broadcasting Corporation (CBC), inaugurated November 2, 1936,^[28] has had the role of representating Canadians.^[29] CBC was established by the Broadcasting Act which received royal assent on June 23, 1936 (Statutes of Canada, 1 Edward VIII, Chap. 24)^[28]following "a Royal Commission that was concerned about the growing American influence in radio."^[29] Radios, television and the CBC have significantly helped reunite Canadians and build its sovereignty.^[30]^[29]

History

For more details on this topic, see History of telecommunication.

Early telecommunications

A replica of one of Chappe'ssemaphore towers.

In the Middle Ages, chains of beacons were commonly used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon in advance. One notable instance of their use was during the Spanish Armada, when a beacon chain relayed a signal from Plymouth to London.^[31]

In 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system (or semaphore line) between Lille and Paris.^[32] However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres (six to nineteen miles). As a result of competition from the electrical telegraph, the last commercial line was abandoned in 1880.^[33]

Homing pigeons have occasionally been used through history by different cultures. Pigeon post is thought to have Persians roots and was used by the Romans to aid their military. Frontinus said that Julius Ceasar used pigeons as messengers in his conquest of Gaul.^[34] The Greeks also conveyed the names of the victors at the Olympic Games to various cities using homing pigeons.^[35] In the early 19th century, the Dutch government used the system in Java and Sumatra. And in 1849, Paul Julius Reuter started a pigeon service to fly stock prices between Aachen and Brussels, a service that operated for a year until the gap in the telegraph link was closed.^[36]

Telegraph and telephone

Sir Charles Wheatstone and Sir William Fothergill Cooke invented the electric telegraph in 1837.^[37] Also, the first commercial electrical telegraph is purported to have been constructed by Wheatstone and Cooke and opened on 9 April 1839.^{[citation needed]} Both inventors viewed their device as "an improvement to the [existing] electromagnetic telegraph" not as a new device.^[38]

Samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837. His code was an important advance over Wheatstone's signaling method. The first transatlantic telegraph cable was successfully completed on 27 July 1866, allowing transatlantic telecommunication for the first time.^[39]

The conventional telephone was invented independently by Alexander Bell and Elisha Gray in 1876.^[40] Antonio Meucci invented the first device that allowed the electrical transmission of voice over a line in 1849. However Meucci's device was of little practical value because it relied upon the electrophonic effect and thus required users to place the receiver in their mouth to “hear” what was being said.^[41] The first commercial telephone services were set-up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London.^[42]^[43]

Radio and television

In 1832, James Lindsay gave a classroom demonstration of wireless telegraphy to his students. By 1854, he was able to demonstrate a transmission across the Firth of Tay from Dundee, Scotland to Woodhaven, a distance of two miles (3 km), using water as the transmission medium.^[44] In December 1901, Guglielmo Marconi established wireless communication between St. John's, Newfoundland (Canada) andPoldhu, Cornwall (England), earning him the 1909 Nobel Prize in physics (which he shared with Karl Braun).^[45] However small-scale radio communication had already been demonstrated in 1893 by Nikola Tesla in a presentation to the National Electric Light Association.^[46]

On 25 March 1925, John Logie Baird was able to demonstrate the transmission of moving pictures at the London department store Selfridges. Baird's device relied upon the Nipkow disk and thus became known as the mechanical television. It formed the basis of experimental broadcasts done by the British Broadcasting Corporation beginning 30 September 1929.^[47] However, for most of the twentieth century televisions depended upon the cathode ray tube invented by Karl Braun. The first version of such a television to show promise was produced by Philo Farnsworth and demonstrated to his family on 7 September 1927.^[48]

Computer networks and the Internet

On 11 September 1940, George Stibitz was able to transmit problems using teletype to his Complex Number Calculator in New York and receive the computed results back at Dartmouth College in New Hampshire.^[49] This configuration of a centralized computer or mainframe with remote dumb terminals remained popular throughout the 1950s. However, it was not until the 1960s that researchers started to investigatepacket switching — a technology that would allow chunks of data to be sent to different computers without first passing through a centralized mainframe. A four-node network emerged on 5 December 1969; this network would become ARPANET, which by 1981 would consist of 213 nodes.^[50]

ARPANET's development centred around the Request for Comment process and on 7 April 1969, RFC 1 was published. This process is important because ARPANET would eventually merge with other networks to form the Internet and many of the protocols the Internet relies upon today were specified through the Request for Comment process. In September 1981, RFC 791 introduced the Internet Protocol v4 (IPv4) and RFC 793 introduced the Transmission Control Protocol (TCP) — thus creating the TCP/IP protocol that much of the Internetrelies upon today.

However, not all important developments were made through the Request for Comment process. Two popular link protocols for local area networks (LANs) also appeared in the 1970s. A patent for the token ring protocol was filed by Olof Soderblom on 29 October 1974 and a paper on the Ethernet protocol was published by Robert Metcalfe and David Boggs in the July 1976 issue of Communications of the ACM.^[51]^[52]

Modern operation

Telephone

Optical fiberprovides cheaper bandwidth for long distance communication

In an analogue telephone network, the caller is connected to the person he wants to talk to by switches at varioustelephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in the caller's handset. This electrical signal is then sent through the network to the user at the other end where it is transformed back into sound by a small speakerin that person's handset. There is a separate electrical connection that works in reverse, allowing the users to converse.^[53]^[54]

The fixed-line telephones in most residential homes are analogue — that is, the speaker's voice directly determines the signal's voltage. Although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting the signals to digital for transmission before converting them back to analogue for reception. The advantage of this is that digitized voice data can travel side-by-side with data from the Internet and can be perfectly reproduced in long distance communication (as opposed to analogue signals that are inevitably impacted by noise).

Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204 m), Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa) (153.5 m), North America (148 m) and Latin America (102 m).^[55] In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth.^[56] Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.^[57]

There have also been dramatic changes in telephone communication behind the scenes. Starting with the operation of TAT-8 in 1988, the 1990s saw the widespread adoption of systems based on optic fibres. The benefit of communicating with optic fibres is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today's optic fibre cables are able to carry 25 times as many telephone calls as TAT-8.^[58] This increase in data capacity is due to several factors: First, optic fibres are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable.^[59] Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre.^[60]^[61]

Assisting communication across many modern optic fibre networks is a protocol known as Asynchronous Transfer Mode (ATM). The ATM protocol allows for the side-by-side data transmission mentioned in the second paragraph. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a traffic contract with that pathway. The traffic contract is essentially an agreement between the client and the network about how the network is to handle the data; if the network cannot meet the conditions of the traffic contract it does not accept the connection. This is important because telephone calls can negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller's voice is not delayed in parts or cut-off completely.^[62] There are competitors to ATM, such as Multiprotocol Label Switching (MPLS), that perform a similar task and are expected to supplant ATM in the future.^[63]

Radio and television

Digital television standards and their adoption worldwide.

In a broadcast system, a central high-powered broadcast tower transmits a high-frequency electromagnetic wave to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The antenna of the receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).^[64]^[65]

The broadcast media industry is at a critical turning point in its development, with many countries moving from analogue to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable integrated circuits. The chief advantage of digital broadcasts is that they prevent a number of complaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output. In a simplified example, if a binary message 1011 was transmitted with signal amplitudes [1.0 0.0 1.0 1.0] and received with signal amplitudes [0.9 0.2 1.1 0.9] it would still decode to the binary message 1011 — a perfect reproduction of what was sent. From this example, a problem with digital transmissions can also be seen in that if the noise is great enough it can significantly alter the decoded message. Using forward error correction a receiver can correct a handful of bit errors in the resulting message but too much noise will lead to incomprehensible output and hence a breakdown of the transmission.^[66]^[67]

In digital television broadcasting, there are three competing standards that are likely to be adopted worldwide. These are the ATSC, DVB andISDB standards; the adoption of these standards thus far is presented in the captioned map. All three standards use MPEG-2 for video compression. ATSC uses Dolby Digital AC-3 for audio compression, ISDB uses Advanced Audio Coding (MPEG-2 Part 7) and DVB has no standard for audio compression but typically uses MPEG-1 Part 3 Layer 2.^[68]^[69] The choice of modulation also varies between the schemes. In digital audio broadcasting, standards are much more unified with practically all countries choosing to adopt the Digital Audio Broadcastingstandard (also known as the Eureka 147 standard). The exception being the United States which has chosen to adopt HD Radio. HD Radio, unlike Eureka 147, is based upon a transmission method known as in-band on-channel transmission that allows digital information to "piggyback" on normal AM or FM analogue transmissions.^[70]

However, despite the pending switch to digital, analogue receivers still remain widespread. Analogue television is still transmitted in practically all countries. The United States had hoped to end analogue broadcasts on 31 December 2006; however, this was recently pushed back to 17 February 2009.^[71] For analogue television, there are three standards in use (see a map on adoption here). These are known as PAL, NTSCand SECAM. For analogue radio, the switch to digital is made more difficult by the fact that analogue receivers are a fraction of the cost of digital receivers.^[72]^[73] The choice of modulation for analogue radio is typically between amplitude modulation (AM) or frequency modulation(FM). To achieve stereo playback, an amplitude modulated subcarrier is used for stereo FM.

The Internet

The OSI reference model

The Internet is a worldwide network of computers and computer networks that can communicate with each other using the Internet Protocol.^[74] Any computer on the Internet has a unique IP address that can be used by other computers to route information to it. Hence, any computer on the Internet can send a message to any other computer using its IP address. These messages carry with them the originating computer's IP address allowing for two-way communication. In this way, the Internet can be seen as an exchange of messages between computers.^[75]

As of 2008, an estimated 21.9% of the world population has access to the Internet with the highest access rates (measured as a percentage of the population) in North America (73.6%), Oceania/Australia (59.5%) and Europe (48.1%).^[76] In terms of broadband access, Iceland(26.7%), South Korea (25.4%) and the Netherlands (25.3%) led the world in 2005.^[77]

The Internet works in part because of protocols that govern how the computers and routers communicate with each other. The nature of computer network communication lends itself to a layered approach where individual protocols in the protocol stack run more-or-less independently of other protocols. This allows lower-level protocols to be customized for the network situation while not changing the way higher-level protocols operate. A practical example of why this is important is because it allows an Internet browser to run the same code regardless of whether the computer it is running on is connected to the Internet through an Ethernet or Wi-Fi connection. Protocols are often talked about in terms of their place in the OSI reference model (pictured on the right), which emerged in 1983 as the first step in an unsuccessful attempt to build a universally adopted networking protocol suite.^[78]

For the Internet, the physical medium and data link protocol can vary several times as packets traverse the globe. This is because the Internet places no constraints on what physical medium or data link protocol is used. This leads to the adoption of media and protocols that best suit the local network situation. In practice, most intercontinental communication will use the Asynchronous Transfer Mode (ATM) protocol (or a modern equivalent) on top of optic fibre. This is because for most intercontinental communication the Internet shares the same infrastructure as the public switched telephone network.

At the network layer, things become standardized with the Internet Protocol (IP) being adopted for logical addressing. For the world wide web, these “IP addresses” are derived from the human readable form using the Domain Name System (e.g. 72.14.207.99 is derived fromwww.google.com). At the moment, the most widely used version of the Internet Protocol is version four but a move to version six is imminent.^[79]

At the transport layer, most communication adopts either the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). TCP is used when it is essential every message sent is received by the other computer where as UDP is used when it is merely desirable. With TCP, packets are retransmitted if they are lost and placed in order before they are presented to higher layers. With UDP, packets are not ordered or retransmitted if lost. Both TCP and UDP packets carry port numbers with them to specify what application or process the packet should be handled by.^[80] Because certain application-level protocols use certain ports, network administrators can restrict Internet access by blocking the traffic destined for a particular port.

Above the transport layer, there are certain protocols that are sometimes used and loosely fit in the session and presentation layers, most notably the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. These protocols ensure that the data transferred between two parties remains completely confidential and one or the other is in use when a padlock appears at the bottom of your web browser.^[81] Finally, at the application layer, are many of the protocols Internet users would be familiar with such as HTTP (web browsing),POP3 (e-mail), FTP (file transfer), IRC (Internet chat), BitTorrent (file sharing) and OSCAR (instant messaging).

Some of the most popular internet telecommunications applications include e-mail, instant messaging, browsing the sites, and the use of various media outlets as well as chat groups. Today just about everyone has at least one e-mail address if not two or three. When the network is not bogged down messages can travel anywhere in the world in a matter of a few seconds or minutes depending on the data and its size (O’Brian,Marakas,2008). Instant messaging is a common and convenient way to communicate with known individuals in real time. There are plenty of browsers that can be used to navigate the internet; some of the popular ones are Internet Explorer and Firefox. You can get news updates as they happen from your favorite news network online.

Local area networks

Despite the growth of the Internet, the characteristics of local area networks (computer networks that run at most a few kilometres) remain distinct. This is because networks on this scale do not require all the features associated with larger networks and are often more cost-effective and efficient without them.

In the mid-1980s, several protocol suites emerged to fill the gap between the data link and applications layer of the OSI reference model. These were Appletalk, IPX and NetBIOS with the dominant protocol suite during the early 1990s being IPX due to its popularity with MS-DOSusers. TCP/IP existed at this point but was typically only used by large government and research facilities.^[82] As the Internet grew in popularity and a larger percentage of traffic became Internet-related, local area networks gradually moved towards TCP/IP and today networks mostly dedicated to TCP/IP traffic are common. The move to TCP/IP was helped by technologies such as DHCP that allowed TCP/IP clients to discover their own network address — a functionality that came standard with the AppleTalk/IPX/NetBIOS protocol suites.^[83]

It is at the data link layer though that most modern local area networks diverge from the Internet. Whereas Asynchronous Transfer Mode(ATM) or Multiprotocol Label Switching (MPLS) are typical data link protocols for larger networks, Ethernet and Token Ring are typical data link protocols for local area networks. These protocols differ from the former protocols in that they are simpler (e.g. they omit features such asQuality of Service guarantees) and offer collision prevention. Both of these differences allow for more economic set-ups.^[84]

Despite the modest popularity of Token Ring in the 80's and 90's, virtually all local area networks now use wired or wireless Ethernet. At the physical layer, most wired Ethernet implementations use copper twisted-pair cables (including the common 10BASE-T networks). However, some early implementations used coaxial cables and some recent implementations (especially high-speed ones) use optic fibres. Optic fibres are also likely to feature prominently in the forthcoming 10-gigabit Ethernet implementations.^[85] Where optic fibre is used, the distinction must be made between multi-mode fibre and single-mode fibre. Multi-mode fibre can be thought of as thicker optical fibre that is cheaper to manufacture but that suffers from less usable bandwidth and greater attenuation (i.e. poor long-distance performance).^[86]

Serial Protocol Monitoring Agent

2008-10-17T21:16:00.000-07:00

Overview:

Features:

Model PBT-SA-1 SpecialAgent provides a means to monitor a wide variety of legacy non-HMS headend transmission equipment using a standards-based HMS management system. This device is especially cost-effective for applications where a small number of devices are monitored per location. Its simple hardware and embedded operating firmware help to promote greater management system reliability by eliminating complex intermediate PC-based proxy-agent layers and the attendant single point of failure they can cause. This is especially important in large equipment installations.

The SpecialAgent hardware consists of an Ethernet interface, a micro-controller subsystem, a power supply, and a configurable equipment interface port that facilitates customization for proprietary interfaces. The major components of the software are a TCPIP protocol stack, a SNMP agent, an HMS proxy agent, a Web server, and an interface driver.

A built-in SMTP mail client is available on many versions of the SpecialAgent. The mail client can be set up to send alarm messages to another computer or to a mobile phone when an alarm occurs.

The SpecialAgent’s hardware design and the SNMP agent allow the device to interface to a wide variety of headend equipment that use proprietary serial interfaces. The SpecialAgent hardware and software are both designed to make the interface easily adapted to most equipment. The target interface is configured using jumpers that are provided as part of the interface cable assembly. The modular software system allows the proper device driver to be easily integrated into the software. For headend equipment with parallel interfaces, consider the Phoenix ContactAgent.

Each family of equipment monitored requires different SpecialAgent firmware. This firmware is easily downloaded into the SpecialAgent. Consult Phoenix Broadband for the current list of equipment supported.

The micro-controller subsystem provides for storage of nonvolatile information as well as remote firmware download. The SpecialAgent is powered from a low voltage plug-in wall transformer in cases where power is not provided by the equipment interface.

The target device is monitored and controlled using the HMS standard SNMP MIBs. Proprietary MIBS are used in situations where the HMS MIBs are not appropriate. The HMS proxy agent performs all HMS administrative and alarm processing functions for the target device. The SpecialAgent also includes a Web Server that allows any PC to access basic monitoring information using only a Web browser.

More technical information about the technology built into the SpecialAgent can be found in the nanoAgent datasheet. Contact Phoenix Broadband Technologies for additional information.

What are broadband technologies?

2008-10-15T00:20:00.000-07:00

Simply put, broadband technologies strive to offer you a single point access to a host of different services. Consider this: In an office environment, you have a local computer network, an EPABX system, a fax line, separate servers for corporate Internet access and so on. Broadband is all about combining all of the seemingly disparate services into a single, unified network.
It’s not as if broadband is something new: ISDN lines (integrated services digital network) have been around for years, which, at a rudimentary level, managed to combine voice, video and data. But they were frightfully expensive and needed proprietary software to run.

Why broadband now?

Internet protocol, or IP for short. Internet protocol has made convergent networks not only technologically possible, but also commercially viable. There is a fine technological difference at a macro level. Conventional telecom networks (often dismissed as POTS — plain old telephony systems) are analogue networks, which treat electrical frequency as a continuous wave form. IP, on the other hand, has introduced “packet switching” technology, which treats all modes of communication as “packets” of 0s and 1s. So, be it video, text, voice or data, all of it is broken down into packets of two digits.
How does broadband work and what are its applications?
Broadband networks can potentially open up new vistas of products and services that will be done through a single device at home. Though it sounds too far out, there are already some instances of broadband technology at work. Consider Internet through cable. Expected to be launched by a host of ISPs in India, Internet through cable allows your TV to act as an Internet access device. This allows constant connectivity at speeds which are simply unimaginable on a normal dial-up connection through a modem. And if you have a PC and a TV and prefer to use your PC for Internet access, the same cable can be split for watching TV and using the Net on your PC without compromising on either speed or quality of access.
The other area where broadband technologies are making their mark is in telephony. Called Voice over IP (VoIP), it uses the same Internet protocol to offer telephony which costs a fraction of what a normal telephone line costs. But it is still in its infancy, and often gets confused with Internet telephony. Internet telephony refers to using your browser to make a phone call while VoIP calls for setting up specific IP telephony exchanges.

How long will it take to happen in India?

IT’S already happening. Apart from the soon-to-be launched Internet through cable, there are other broadband technologies such as ATM (asynchronous transfer mode), xDSL (digital subscriber line), ISDN, and WAN (wide area network) technologies which are being rapidly deployed. Of the lot, ATM and WAN technologies are network gizmos, which link up computers over a specified area, largely meant to function as network points, while the other technologies are directly aimed at users.
xDSL, which is the generic technology, comes in many flavours such as ADSL, RADSL, SDSL, HDSL and so on. What is unique about xDSL is that it uses the same old telephone cable and still offers connectivity at speeds higher than Internet through cable. The hitch is that like every cutting edge technology, xDSL is currently too expensive for Indian users.
To give a comparison, a dial-up modem connection can possibly pump data at 56.6 kbps (kilobits per second) while Internet through cable can optimally deliver 256 kbps. ADSL, the earliest flavour of xDSL, can deliver a blinding 1 mbps (one mb, or megabit = 1,024 kb) which is four times faster than Internet through cable.

Does broadband have any other uses?

Potentially, the market for broadband technologies is huge. Some of its applications include voice, video and multimedia streaming, broadcast TV and radio, interactive gaming and real-time video conferencing

SkyStar USB

2008-10-12T09:49:00.001-07:00

TechniSat offers the optimal Multimedia extension with the SkyStar USB for your PC!

In addition to receiving digital TV and radio programs via satellite, the device is also an extremely cost-effective and reliable solution for reception of data services such as file-delivery or high speed-internet via satellite.

Equipment characteristics

Reception of digital DVB-S television, radio channels and teletext
Reception of data services via satellite dish (Multicast/Unicast, MPE)
Plug & Play
USB 1.1 (USB.ORG certified)
Input Frequencies: 950 - 2.150 MHz
RF-level: -65 to -25 dBm
LNB support: 13V/18V, 350mA max.
DiSEqC 1.0
SCPC and MCPC

SkyStar 2 TV PCI

2008-10-12T09:47:00.000-07:00

TechniSat offers the optimal Multimedia extension with the SkyStar 2 TV for your PC!

In addition to receiving digital TV and radio programs via satellite, the device is also an extremely cost-effective and reliable solution for reception of data services such as file-delivery or high speed-internet via satellite.

Equipment characteristics

Reception of digital DVB-S television, radio channels and teletext
Reception of data services via satellite dish (Multicast/Unicast, MPE)
Plug & Play
PCI card
Input Frequencies: 950 - 2.150 MHz
RF-level: -65 to -25 dBm
LNB support: 13V/18V, 350mA max.
DiSEqC 1.0
SCPC and MCPC

Broadband Internet access

2008-10-12T09:43:00.000-07:00

Broadband Internet access, often shortened to just broadband, is high-speed Internet access—typically contrasted with dial-up access over a modem.

Dial-up modems are generally only capable of a maximum bitrate of 56 kbit/s (kilobits per second) and require the full use of a telephone line—whereas broadband technologies supply at least double this speed and generally without disrupting telephone use. (It should be noted, though, that dial up is not the opposite of broadband, and is used here for practical understanding purposes only.)

Although various minimum speeds have been used in definitions of broadband, ranging up from 64 kbit/s up to 1.0 Mbit/s, the 2006 OECD report ^[1] is typical in counting only download speeds equal to or faster than 256 kbit/s as broadband, and the US FCC currently defines broadband as anything above 768 kbit/s ^[2] ^[3]

Speeds are defined in terms of maximum download because several common consumer broadband technologies such as ADSL are "asymmetric"—supporting much slower maximum upload speeds than download.

"Broadband penetration" is now treated as a key economic indicator.

Overview

*Broadband transmission rates*
Connection	Transmission Speed
DS-1 (Tier 1)	1.544 Mbit/s
E-1	2.048 Mbit/s
DS-3 (Tier 3)	44.736 Mbit/s
OC-3	155.52 Mbit/s
OC-12	622.08 Mbit/s
OC-48	2.488 Gbit/s
OC-192	9.953 Gbit/s
OC-768	39.813 Gbit/s
OC-1536	79.6 Gbit/s
OC-3072	159.2 Gbit/s

Broadband is often called high-speed Internet, because it usually has a high rate of data transmission. In general, any connection to the customer of 256 kbit/s (0.256 Mbit/s) or more is considered broadband Internet. The International Telecommunication Union Standardization Sector (ITU-T) recommendation I.113 has defined broadband as a transmission capacity that is faster than primary rate ISDN, at 1.5 to 2 Mbit/s. The FCC definition of broadband is 200 kbit/s (0.2 Mbit/s) in one direction, and advanced broadband is at least 200 kbit/s in both directions. The Organization for Economic Co-operation and Development (OECD) has defined broadband as 256 kbit/s in at least one direction and this bit rate is the most common baseline that is marketed as "broadband" around the world. There is no specific bitrate defined by the industry, however, and "broadband" can mean lower-bitrate transmission methods. Some Internet Service Providers (ISPs) use this to their advantage in marketing lower-bitrate connections as broadband.

In practice, the advertised bandwidth is not always reliably available to the customer; ISPs often allow a greater number of subscribers than their backbone connection can handle, under the assumption that most users will not be using their full connection capacity very frequently. This aggregation strategy works more often than not, so users can typically burst to their full bandwidth most of the time; however, peer-to-peer (P2P) file sharing systems, often requiring extended durations of high bandwidth, stress these assumptions, and can cause major problems for ISPs who have excessively overbooked their capacity. For more on this topic, see traffic shaping. As takeup for these introductory products increases, telcos are starting to offer higher bit rate services. For existing connections, this most of the time simply involves reconfiguring the existing equipment at each end of the connection.

As the bandwidth delivered to end users increases, the market expects that video on demand services streamed over the Internet will become more popular, though at the present time such services generally require specialized networks. The data rates on most broadband services still do not suffice to provide good quality video, as MPEG-2 video requires about 6 Mbit/s for good results. Adequate video for some purposes becomes possible at lower data rates, with rates of 768 kbit/s and 384 kbit/s used for some video conferencing applications, and rates as low as 100 kbit/s used for videophones using H.264/MPEG-4 AVC. The MPEG-4 format delivers high-quality video at 2 Mbit/s, at the high end of cable modem and ADSL performance.

Increased bandwidth has already made an impact on newsgroups: postings to groups such as alt.binaries.* have grown from JPEG files to entire CD and DVD images. According to NTL, the level of traffic on their network increased from a daily inbound news feed of 150 gigabytes of data per day and 1 terabyte of data out each day in 2001 to 500 gigabytes of data inbound and over 4 terabytes out each day in 2002.^{[citation needed]}

Technology

The standard broadband technologies in most areas are DSL and cable modems. Newer technologies in use include VDSL and pushing optical fiber connections closer to the subscriber in both telephone and cable plants. Fiber-optic communication, while only recently being used in fiber to the premises and fiber to the curb schemes, has played a crucial role in enabling Broadband Internet access by making transmission of information over larger distances much more cost-effective than copper wire technology. In a few areas not served by cable or ADSL, community organizations have begun to install Wi-Fi networks, and in some cities and towns local governments are installing municipal Wi-Fi networks. As of 2006, high speed mobile Internet access has become available at the consumer level in some countries, using the HSDPA and EV-DO technologies. The newest technology being deployed for mobile and stationary broadband access is WiMAX.

DSL (ADSL/SDSL)

Main article: ADSL

Multilinking Modems

It is possible to roughly double dial-up capability with multilinking technology. What is required are two modems, two phone lines, two dial-up accounts, and ISP support for multilinking, or special software at the user end. This option was popular with some high-end users before ISDN, DSL and other technologies became available.

Diamond and other vendors had created dual phone line modems with bonding capability. The speed of dual line modems is faster than 90 kbit/s. To use this modem, the ISP should support line bonding. The Internet and phone charge will be twice the ordinary dial-up charge.

Load balancing takes two internet connections and feeds them into your network as one double speed, more resilient internet connection. By choosing two independent internet providers the load balancing hardware will automatically use the line with least load which means should one line fail, the second one automatically takes up the slack.

ISDN

Integrated Service Digital Network (ISDN) is one of the oldest high-speed digital access methods for consumers and businesses to connect to the Internet. It is a telephone data service standard. Its use in the United States peaked in the late 1990s prior to the availability of DSL and cable modem technologies. Broadband service is usually compared to ISDN-BRI because this was the standard high-speed access technology that formed a baseline for the challenges faced by the early broadband providers. These providers sought to compete against ISDN by offering faster and cheaper services to consumers.

A basic rate ISDN line (known as ISDN-BRI) is an ISDN line with 2 data "bearer" channels (DS0 - 64 kbit/s each). Using ISDN terminal adapters (erroneously called modems), it is possible to bond together 2 or more separate ISDN-BRI lines to reach speeds of 256 kbit/s or more. The ISDN channel bonding technology has been used for video conference applications and high-speed data transmission.

Primary rate ISDN, known as ISDN-PRI, is an ISDN line with 23 DS0 channels and total speed of 1,544 kbit/s (US standard). ISDN E1 (European standard) line is an ISDN lines with 30 DS0 channels and total speed of 2,048 kbit/s. Because ISDN is a telephone-based product, a lot of the terminology and physical aspects of the line are shared by the ISDN-PRI used for voice services. An ISDN line can therefore be "provisioned" for voice or data and many different options, depending on the equipment being used at any particular installation, and depending on the offerings of the telephone company's central office switch. Most ISDN-PRI's are used for telephone voice communication using large PBX systems, rather than for data. One obvious exception is that ISPs usually have ISDN-PRI's for handling ISDN data and modem calls.

It is mainly of historical interest that many of the earlier ISDN data lines used 56 kbit/s rather than 64 kbit/s "B" channels of data. This caused ISDN-BRI to be offered at both 128 kbit/s and 112 kbit/s rates, depending on the central office's switching equipment.

Advantages:

Constant data speed at 64 kbit/s for each DS0 channel.
Two way high speed symmetric data transmission, unlike ADSL.
One of the data channels can be used for phone conversation without disturbing the data transmission through the other data channel. When a phone call is ended, the bearer channel can immediately dial and re-connect itself to the data call.
Call setup is very quick.
Low latency
ISDN Voice clarity is unmatched by other phone services.
Caller ID is almost always available for no additional fee.
Maximum distance from the central office is much greater than it is for DSL.
When using ISDN-BRI, there is the possibility of using the low-bandwidth 16 kbit/s "D" channel for packet data and for always on capabilities.

Disadvantages:

ISDN offerings are dwindling in the marketplace due to the widespread use of faster and cheaper alternatives.
ISDN routers, terminal adapters ("modems"), and telephones are more expensive than ordinary POTS equipment, like dial-up modems.
ISDN provisioning can be complicated due to the great number of options available.
ISDN users must dial in to a provider that offers ISDN Internet service, which means that the call could be disconnected.
ISDN is billed as a phone line, to which is added the bill for Internet ISDN access.
"Always on" data connections are not available in all locations.
Some telephone companies charge unusual fees for ISDN, including call setup fees, per minute fees, and higher rates than normal for other services.

T-1/DS-1

These are highly-regulated services traditionally intended for businesses, that are managed through Public Service Commissions (PSCs) in each state, must be fully defined in PSC tariff documents, and have management rules dating back to the early 1980s which still refer to teletypes as potential connection devices. As such, T-1 services have very strict and rigid service requirements which drive up the provider's maintenance costs and may require them to have a technician on standby 24 hours a day to repair the line if it malfunctions. (In comparison, ISDN and DSL are not regulated by the PSCs at all.) Due to the expensive and regulated nature of T-1 lines, they are normally installed under the provisions of a written agreement, the contract term being typically one to three years. However, there are usually few restrictions to an end-user's use of a T-1, uptime and bandwidth speed may be guaranteed, quality of service may be supported, and blocks of static IP addresses are commonly included.

Since a T-1 was originally conceived for voice transmission, and voice T-1's are still widely used in businesses, it can be confusing to the uninitiated subscriber. It is often best to refer to the type of T-1 being considered, using the appropriate "data" or "voice" prefix to differentiate between the two. A voice T-1 would terminate at a phone company's central office (CO) for connection to the PSTN; a data T-1 terminates at a point of presence (POP) or data center. The T-1 line which is between a customer's premises and the POP or CO is called the local loop. The owner of the local loop need not be the owner of the network at the POP where your T-1 connects to the Internet, and so a T-1 subscriber may have contracts with these two organizations separately.

The nomenclature for a T-1 varies widely, cited in some circles a DS-1, a T1.5, a T1, or a DS1. Some of these try to distinguish amongst the different aspects of the line, considering the data standard a DS-1, and the physical structure of the trunk line a T-1 or T-1.5. They are also called leased lines, but that terminology is usually for data speeds under 1.5 Mbit/s. At times, a T-1 can be included in the term "leased line" or excluded from it. Whatever it is called, it is inherently related to other high-speed access methods, which include T-3, SONET OC-3, and other T-carrier and Optical Carriers. Additionally, a T-1 might be aggregated with more than one T-1, producing an nxT-1, such as 4xT-1 which has exactly 4 times the bandwidth of a T-1.

When a T-1 is installed, there are a number of choices to be made: in the carrier chosen, the location of the demarcation point, the type of channel service unit (CSU) or data service unit (DSU) used, the WAN IP router used, the types of speeds chosen, etc. Specialized WAN routers are used with T-1 lines that route Internet or VPN data onto the T-1 line from the subscriber's packet-based (TCP/IP) network using customer premises equipment (CPE). The CPE typical consists of a CSU/DSU that converts the DS-1 data stream of the T-1 to a TCP/IP packet data stream for use in the customer's Ethernet LAN. It is noteworthy that many T-1 providers optionally maintain and/or sell the CPE as part of the service contract, which can affect the demarcation point and the ownership of the router, CSU, or DSU.

Although a T-1 has a maximum of 1.544 Mbit/s, a fractional T-1 might be offered which only uses an integer multiple of 128 kbit/s for bandwidth. In this manner, a customer might only purchase 1/12th or 1/3 of a T-1, which would be 128 kbit/s and 512 kbit/s, respectively.

T-1 and fractional T-1 data lines are symmetric, meaning that their upload and download speeds are the same.

Wired Ethernet

Where available, this method of broadband connection to the Internet would indicate that the Internet access is very fast. However, just because Ethernet is offered doesn't mean that the full 10, 100, or 1000 Mbit/s connection is able to be utilized for direct Internet access. In a college dormitory for example, the 100 Mbit/s Ethernet access might be fully available to on-campus networks, but Internet access speeds might be closer to 4xT-1 speed (6 Mbit/s). If you are sharing a broadband connection with others in a building, the access speed of the leased line into the building would of course govern the end-user's speed.

However, in certain locations, true Ethernet broadband access might be available. This would most commonly be the case at a POP or a data center, and not at a typical residence or business. When Ethernet Internet access is offered, it could be fiber-optic or copper twisted pair, and the speed will conform to standard Ethernet speeds of up to 10 Gbit/s. The primary advantage is that no special hardware is needed for Ethernet. Ethernet also has a very low latency.

Rural broadband

One of the great challenges of broadband is to provide service to potential customers in areas of low population density, such as to farmers and ranchers. In cities where the population density is high, it is easy for a service provider to recover equipment costs, but each rural customer may require expensive equipment to get connected.

Several rural broadband solutions exist, though each has its own pitfalls and limitations. Some choices are better than others, but are dependent on how proactive the local phone company is about upgrading their rural technology.

Wireless Internet Service Provider (WISPs) are rapidly becoming a popular broadband option for rural areas.

Satellite Internet

Main article: Satellite Internet

This employs a satellite in geostationary orbit to relay data from the satellite company to each customer. Satellite Internet is usually among the most expensive ways of gaining broadband Internet access, but in rural areas it may only compete with cellular broadband. However, costs have been coming down in recent years to the point that it is becoming more competitive with other high-speed options.

Satellite Internet also has a high latency problem caused by the signal having to travel 35,000 km (22,000 miles) out into space to the satellite and back to Earth again. The signal delay can be as much as 500 milliseconds to 900 milliseconds, which makes this service unsuitable for applications requiring real-time user input such as certain multiplayer Internet games and first-person shooters played over the connection. Despite this, it is still possible for many games to be played, but the scope is limited to real-time strategy or turn-based games. The functionality of live interactive access to a distant computer can also be subject to the problems caused by high latency. These problems are more than tolerable for just basic email access and web browsing and in most cases are barely noticeable.

There is no simple way to get around this problem. The delay is primarily due to the speed of light being only 300,000 km/second (186,000 miles per second). Even if all other signaling delays could be eliminated it still takes the electromagnetic wave 233 milliseconds to travel from ground to the satellite and back to the ground, a total of 70,000 km (44,000 miles) to travel from the user to the satellite company.

Since the satellite is usually being used for two-way communications, the total distance increases to 140,000 km (88,000 miles), which takes a radio wave 466 ms to travel. Factoring in normal delays from other network sources gives a typical connection latency of 500-700 ms. This is far worse latency than even most dial-up modem users' experience, at typically only 150-200 ms total latency.

Most satellite Internet providers also have a FAP (Fair Access Policy). Perhaps one of the largest disadvantages of satellite Internet, these FAPs usually throttle a user's throughput to dial-up speeds after a certain "invisible wall" is hit (usually around 200 MB a day). This FAP usually lasts for 24 hours after the wall is hit, and a user's throughput is restored to whatever tier they paid for. This makes bandwidth-intensive activities nearly impossible to complete in a reasonable amount of time (examples include P2P and newsgroup binary downloading).

Advantages

True global broadband Internet access availability
Mobile connection to the Internet (with some providers)

Disadvantages

High latency compared to other broadband services, especially 2-way satellite service
Unreliable: drop-outs are common during travel, inclement weather, and during sunspot activity
The narrow-beam highly directional antenna must be accurately pointed to the satellite orbiting overhead
The Fair Access Policy limits heavy usage, if applied by the service provider
VPN use is discouraged, problematic, and/or restricted with satellite broadband, although available at a price
One-way satellite service requires the use of a modem or other data uplink connection
Satellite dishes are very large. Although most of them employ plastic to reduce weight, they are typically between 80 and 120 cm (30 to 48 inches) in diameter.

Cellular broadband

Cellular phone towers are very widespread, and as cellular networks move to third generation (3G) networks they can support fast data; using technologies such as EVDO, HSDPA and UMTS.

These can give broadband access to the Internet, with a cell phone, with Cardbus, ExpressCard, or USB cellular modems, or with cellular broadband routers, which allow more than one computer to be connected to the Internet using one cellular connection.

Advantages

The only broadband connection available on many cell phones and PDAs
Mobile wireless connection to the Internet
Available in all metropolitan areas, most large cities, and along major highways. (See a map)
No need to aim an antenna in most cases
The antenna is extremely small compared to a satellite dish
Low latency compared to satellite Internet
Higher availability than WiFi "Hot Spots"
A traveler who already has cellular broadband will not need to pay different WiFi Hot Spot providers for access.

Disadvantages

Unreliable: drop-outs are common during travel and during inclement weather
Not a truly nationwide service
Speed can vary widely throughout the day, sometimes falling well below the 400 kbit/s target during peak times.
Asymmetric service: the upload rate is always much slower than the download rate.
High latency compared to DSL and Cable broadband services.
Often more costly compared to other methods

Power-line Internet

This is a new service still in its infancy that may eventually permit broadband Internet data to travel down standard high-voltage power lines. However, the system has a number of complex issues, the primary one being that power lines are inherently a very noisy environment. Every time a device turns on or off, it introduces a pop or click into the line. Energy-saving devices often introduce noisy harmonics into the line. The system must be designed to deal with these natural signaling disruptions and work around them.

Broadband over power lines (BPL), also known as Power line communication, has developed faster in Europe than in the US due to a historical difference in power system design philosophies. Nearly all large power grids transmit power at high voltages in order to reduce transmission losses, then near the customer use step-down transformers to reduce the voltage. Since BPL signals cannot readily pass through transformers, repeaters must be attached to the transformers. In the US, it is common for a small transformer hung from a utility pole to service a single house. In Europe, it is more common for a somewhat larger transformer to service 10 or 100 houses. For delivering power to customers, this difference in design makes little difference, but it means delivering BPL over the power grid of a typical US city will require an order of magnitude more repeaters than would be required in a comparable European city.

The second major issue is signal strength and operating frequency. The system is expected to use frequencies in the 10 to 30 MHz range, which has been used for decades by licensed amateur radio operators, as well as international shortwave broadcasters and a variety of communications systems (military, aeronautical, etc.). Power lines are unshielded and will act as transmitters for the signals they carry, and have the potential to completely wipe out the usefulness of the 10 to 30 MHz range for shortwave communications purposes.

Wireless ISP

This typically employs the current low-cost 802.11 Wi-Fi radio systems to link up remote locations over great distances, but can use other higher-power radio communications systems as well.

Traditional 802.11b was licensed for omnidirectional service spanning only 100-150 meters (300-500 ft). By focusing the signal down to a narrow beam with a Yagi antenna it can instead operate reliably over a distance of many miles.

Rural Wireless-ISP installations are typically not commercial in nature and are instead a patchwork of systems built up by hobbyists mounting antennas on radio masts and towers, agricultural storage silos, very tall trees, or whatever other tall objects are available. There are currently a number of companies that provide this service. A wireless Internet access provider map for USA is publicly available for WISPS.

iBlast

iBlast was the brand name for a theoretical high-speed (7 Mbit/s), one-way digital data transmission technology from Digital TV station to users that was developed between June 2000 to October 2005.

Advantages:

Low cost, high speed data transmission from TV station to users. This technology can be used for transmitting website / files from Internet.

Disadvantages:

One way data transmission and should be combined with other method of data transmission from users to TV station.
Privacy/security.
Lack of 8VSB tuner built into many consumer electronic devices needed to receive the iBlast signal.

In the end, the disadvantages outweighed the advantages and the glut of fiberoptic capacity that ensued following the collapse of the Internet bubble drove the cost of transmission so low that an ancillary service such as this was unnecessary, and the company folded at the end of 2005. The partner television stations as well as over 500 additional television stations not part of the iBlast Network continue to transmit separate digital signals as mandated by the Telecommunications Act of 1996.

WorldSpace

WorldSpace is a digital satellite radio network based in Washington DC. It covers most of Asia and Europe plus all of Africa by satellite. Beside the digital audio, users can receive one way high speed digital data transmission (150 Kilobit/second) from the satellite.

Advantages:

Low cost (US$ 100) receiver that combines a digital radio receiver and a data receiver. This technology can be used for transmitting websites / files from Internet.
Access from remote places in Asia and Africa.

Disadvantages:

One way data transmission and should be combined with other method of data transmission from users to Worldspace HQ,
Privacy/security.

Pricing

The examples and perspective in this article or section may not represent a worldwide view of the subject.
Please improve this article or discuss the issue on the talk page.

Traditionally, ISPs have used an "all you can eat" or flat rate model, with pricing determined by the maximum bitrate chosen by the customer. However the use of high bandwidth applications is increasing rapidly, with increased consumer demand for streaming content such as video on demand, as well as peer-to-peer file sharing.

For ISPs who are bandwidth limited, the "all you can eat" model may become unsustainable as demand for bandwidth increases. Fixed costs represent 80-90% of the cost of providing broadband service, and although most ISPs keep their cost secret, the total cost (January 2008) is estimated to be about $0.10 per gigabyte. Currently some ISPs estimate that about 5% of users consume about 50% of the total bandwidth [1].

Some ISPs have begun experimenting with usage-based pricing, notably a Time Warner test in Beaumont, Texas. Bell Canada has imposed bandwidth caps on customers, with pricing ranging from $1 to $7.50 per gigabyte for usage over certain limits. For comparison, note that a typical standard-definition movie is 700MB-1.2GB, while a high-definition movie is 6GB-12GB. This could conceivably result in a charge of $90 to view a movie.

An often overlooked analysis when choosing an internet provider is comparing the different DSL and cable internet services at the plan level. Doing so will ensure that consumers do not overpay for speed they will not utilize. While this comparison can be cumbersome, there are resources like http://highspeed-internet-providers.com that assist in the decision making process.

Broadband worldwide

Main article: Internet access worldwide

Broadband Technologies

Voice Over Internet Protocol

Telecommunication

Etymology

Key concept

Basic elements

Analogue or digital

Networks

Channels

Society and telecommunication

Altering of Space and Time

Economics

Microeconomics

Macroeconomics

Social

Cellular Telephone Industry

Sovereignty

Canadian Telecommunications Act

Canadian Broadcasting Act

History

Early telecommunications

Telegraph and telephone

Radio and television

Computer networks and the Internet

Modern operation

Telephone

Radio and television

The Internet

Local area networks

Serial Protocol Monitoring Agent

What are broadband technologies?

SkyStar USB

SkyStar 2 TV PCI

Broadband Internet access

Overview

Technology

DSL (ADSL/SDSL)

Multilinking Modems

ISDN

T-1/DS-1

Wired Ethernet

Rural broadband

Satellite Internet

Cellular broadband

Power-line Internet

Wireless ISP

iBlast

WorldSpace

Pricing

Broadband worldwide

See also

Broadband technologies

Broadband implementations

Future broadband implementations

Broadband applications