BROADBAND: A PRIMER ON TELECOMMUNICATIONS TECHNOLOGY.
Americans shop, trade stocks, pay bills and search for information on-line. This ability to rapidly send or receive digitized information has transformed the global economy. Unfortunately, the technologies to provide this capability -- the technologies of broadband Internet access- are not penetrating all areas of the country equally.
A recent article in the New York Times was called "Life in the Slow Lane: Rural Residents are Frustrated by Sluggish Web Access." It described a real estate agent in Pryor, Oklahoma, who uses a dial-up modem to connect through her local Internet Service Provider. According to the article, "the connection is never very fast -- 33 kilobits per second at most, although she has a 56K modem -- and at night it slows to a crawl." Like millions of others, she wants a faster Internet connection. But unlike urban and suburban Americans, she is stuck with slow dial-up service because there are no other choices in Pryor, Oklahoma, population 8,300.
This lady may have been inconvenienced, but the problem she faces in other circumstances could turn out to be a matter of life and death. Many communities cannot support medical specialists, but journals are full of stories about how sick or injured people can be diagnosed from afar. Digital technology and advanced imaging systems allow doctors to diagnose and design treatments for people living thousands of miles away from hi-tech medical facilities. The technology for delivering a fine-grained signal must be precise, allowing doctors to peer with precision into a human body using a wire smaller than your little finger.
You may recall reading about Dr. Jerri Nielsen, a physician who served at the Amundsen-Scott South Pole Research Center at the South Pole. Dr. Nielsen found a lump in her breast. Worse, it was the Antarctic winter, and no planes could get in or out for a six-month period. Because of the Internet, she was able to e-mail photographs of slides of the tumor to doctors back home, and they were able to guide her through her initial treatment.
These examples show the obstacles to and the promise of broadband technology. Most urban Americans have fast, stable access to the Internet. The generic term for this is "broadband." It refers to the ability to transmit and receive large amounts of data to and from a computer.
The ability to transmit this data is determined by the size of the "pipe" through which it moves, referred to as bandwidth. As the Internet has become more graphical and interactive, the need for broadband has increased.
Numerous applications have been developed that require greater bandwidth to be used effectively. Broadband services include interactive purchasing, video-on-demand, remote interactive medical services, remote access to stored video materials, and two-way teleconferencing. As a result, government agencies, hospitals, and consumers all want broadband access.
Additionally, many electric cooperatives are investigating telecommunications technologies, and cooperative boards are being asked to invest in broadband infrastructure. But exactly what are these technologies, how do they work, and which have applications in rural America?
This Primer attempts to answer these questions. Its objective is to explain basic broadband technologies to non-technical readers. It will begin with a
brief explanation of the "bits" and "bytes" of the digital world, and then explain the role of the Internet Service Provider. Finally, it will review specific technologies that currently deliver Internet content to users, including 56K dial-up, satellite, Digital Subscriber Line, ISDN, terrestrial wireless, cable and fiber. A glossary of telecommunications phrases and concepts is included at the end of the Primer.
II. The Digital Divide Versus Broadband Access
About 60 percent of Americans have a home computer, and about 50% have logged on to the Internet. It has become a dramatic force in people's lives. Although the Internet is fairly new to the consumer market, it has already divided the nation into two camps: the 'technology haves' and 'have nots'. This division is commonly called the "Digital Divide," and primarily relates to the distinction between those who use or don't use the Internet. As we'll see below, Internet use correlates with socioeconomic status.
Broadband access is different. It relates not to the socioeconomic status of the user, but to the availability of technologies that provide high-speed access to the Internet. In many rural areas of the Untied States, those technological options are not now available.
Let's begin with the Digital Divide. Millions of Americans view the Internet the same way they view their telephone, car, or microwave: as an essential part of life. According to a AOL/Roper Starch Cyberstudy, 66% of Internet users would prefer a computer with Internet connection to a telephone or television if stranded on a desert island.
However, many Americans are not on-line and are not taking advantage of the resources found on the Internet. According to the White House, 45 percent of homes where at least one person has a college degree are connected to the Internet. This compares to 14 percent of homes where no one is a college graduate. Sixty percent of households with incomes above $75,000 have Internet access while households with incomes in the $20,000-25,000 range only have a 14 percent on-line rate.
The trends of the Digital Divide are clear. Lower income consumers are at a disadvantage and run the risk of being left behind. This has important implications for rural America as it has historically experienced lower incomes than urban areas.
The Digital Divide is primarily a socioeconomic problem related to users. In contrast, broadband access is a business problem because of rural density. It is not about owning and using computers; it is about having access to a telecommunications infrastructure that allows users to take advantage of what the Internet has to offer. According to a major study produced jointly by the U.S. Department of Agriculture and the Department of Commerce, "...rural areas are currently lagging far behind urban areas in broadband availability.'' 1
This report claims that two broadband technologies are currently being deployed at a high rate in the United States: cable modem and digital subscriber line (DSL). But each of these is being deployed primarily in urban areas. As shown in Exhibit 1, cable, the most used broadband technology in the United States, is available in more than 65% of cities with populations over 250,000, but is available in fewer than 5% of towns with populations less than 10,000.
DSL is the second most used broadband technology. As shown in Exhibit 2, more than 56%] of cities with populations exceeding 100,000 have DSL, but fewer than 5% of cities less than 10,000 have such service.
The reason for the slower deployment of broadband technologies in rural areas is economic. Just as with electric distribution, the cost to serve a consumer with a wireline carrier increases the greater the distance among customers. Cable and DSL are also limited because of physical limitations on how far their signals can be transmitted.
The government report notes that newer technologies are becoming available, and some, like satellite broadband service, have potential for rural areas because the geographic location of the consumer has virtually no effect on the cost of the service. Several broadband satellite services are now available, along with terrestrial wireless services, including multipoint multichannel distribution systems (MMDS) and local-multipoint distribution systems (LMDS).
These broadband technologies will be explained later. First, however, we must address the "bits and bytes" of digital language.
III. The Language of Digital Technology
Computers and microprocessors are driving the global economy, but how do these technologies really work? What is digital technology?
Signals are of two kinds: analog and digital. An analog signal (Exhibit 3) is a representation of a continuous physical variable, like a sound wave. In contrast, digital signals (Exhibit 4) represent variables mathematically. Because of an essential feature of electricity, it is an ideal medium for sending digital information. It recognizes two possible states: OPEN or CLOSED. This fact about electricity is the foundation of all computer driven devices: the number "1" is used to represent a closed circuit, and the number "0" is used to represent an open circuit. Hence, electricity is more than just the energy used to make computers work. It is the medium that computers use to do their job. Rapid, tiny changes in voltage represent the ones and zeros that make up digital information. Since computer language has only two symbols, it is called a binary language. This accounts for the translation, storage and manipulation of all information within or between computers. Each 1 or 0 is a bit of information.
Bits can combined into 8-unit sequences called bytes. Consider the following sequence:
These numbers are the code through which information can be expressed digitally. Underneath each number is a one or a zero.
A one means that number is activated. A zero means that it is not. Imagine that we want to activate some mix of these numbers to achieve the number 72. Since it is not on the list, we must add two numbers: 64 plus 8 equals 72. Symbolically, this can be represented as:
We have presented this because computer engineers have agreed to follow the American Standard Code for Information Interchange (ASCII) and according to this code, 72 represents the capital letter H. (See Exhibit 5 for a list of ASCII conventions.)
According to the same ASCII convention, the small letter i is represented by 105, which is expressed by the following binary formula: 0-1-1-0-1-0-0-1.
If you add one more sequence and stream a total of 24 bits of information....
you have the computer language equivalent of "Hi!".
IV. Properties of Digital Communication
The Os and Is of digital data mean more than just "on and off". They also mean perfect copying. When information is translated into a digital format, it can be electronically manipulated, preserved and accessed perfectly every time. The millionth copy of a computer file is exactly the same as the original.
This makes computer storage of files an effective solution for saving documents. It also allows a user to e-mail a file to others and know that the file will arrive in the same format as it left, assuming both users have the same software and compatible computer systems. (See the sidebar for a discussion of the relation between files and digital bits.)
Contrast this with analog information, which is subject to distortion whenever it is amplified or repeated. Exhibit 6 contrasts the deterioration of analog versus digital information. As we will see later, communication technologies require "repeaters" to strengthen signals that must be sent over a distance. Every time analog information is sent through a repeater, it deteriorates and loses some of its clarity. As is implied in the exhibit, digital signals do not deteriorate.
The 1s and 0s of digital communication cannot be transmitted to the Internet without being translated into a format that is used by the medium doing the transmission. In the example of a dial-up connection that uses a telephone line, the computer signal must be converted from the digital pulses of the computer to the audio frequencies that the telephone system can handle, and then back to digital pulses on the other end (Exhibit 7). This is done with a modulator/demodulator, known as a modem. Virtually all Internet access technologies (e.g., cable, DSL, ISDN, etc.) use some type of modem to send information from the sender to the receiver.
V. Speed on the Internet
Internet speed refers to the amount of data that can be transferred from one computer to another. This is measured in bits per second. Bit stands for Binary Digit. As we saw earlier, binary digits are the smallest elements of computer information: the ones and zeros that constitute the basic building blocks of all computer language.
The speed at which users send or receive messages over the Internet is measured in the number of bits that can be transferred either from the Internet (downstream) or back to the Internet (upstream) in a second. Typically the speed will be expressed in the thousands (1 kilobit is equal to 1,000 bits) or millions (1 megabit is equal to I million bits) of bits per second. (See Exhibit 8 for a conversion chart of data speeds.)
A 56K modem has a maximum bit transfer rate of 56,000 bits per second. Fifty-six thousand ones and zeros flow through every second. This may sound like a lot, but it takes several bits of information to compose a message digitally. For example, this document that you are reading now, including the exhibits, is made up of over 1,200,000 bits of information. Each letter, punctuation mark, and space requires at least 8 bits.
This factor becomes even more important when sending picture files or video images over the Internet. Such files can consist of several million bits of data. The greater the number of bits, the faster the speed and the greater the bandwidth required to achieve the benefit of the Internet2. A PowerPoint presentation with streaming video can be over 30,000,000 bits in size. With a 56K dial-up connection, it will take over one hour to receive the message, and that assumes it is in perfect working order and that there are no other bottlenecks within the system.
With a fiber optic broadband connection, the same file would take less than ten seconds3. Exhibit 9 presents the transfer times necessary to deliver a 10 megabyte (10 million bit) file through a number of narrowband and broadband modems.
VI. The Role of the ISP
The Internet Service Provider (ISP) is an essential participant in providing access to users. The Internet has often been described as an "information superhighway." According to this analogy, the ISP is an on-ramp to the superhighway: it is the entry point where users have controlled access to the world's high-speed data networks. Because of this central role, it is important for policy makers to understand what ISPs do.
Exhibit 10 presents an image of an ISP. It houses a set of modems (to receive calls from consumers), servers (computers that store web sites and messages), and routers (computers that send messages to other ISPs, or back to consumers). To oversimplify, the ISP moves IP packets to and from some National Backbone provider. We'll explain later what that means.
Exhibit 11 presents an image of the ISP in relation to the Internet. Several points are important. First, there are higher-order ISPs. A local ISP might serve a few thousand consumers. That ISP's routers send signals to a Regional ISP that serves several local ISPs. At the top of the ladder are approximately 10 national ISPs such as UUNet (a divison of MCIWorldcom), AT&T, and Sprint. These companies each have their own National Backbone, an ultra-high-speed fiber optic network that crosses the country. The exhibit shows just one of these National Backbone systems 
The major access points to the Internet are known as NAPs (Network Access Points). The NAPs connect Metropolitan Area Exchanges (MAE). The original four MAEs were in New Jersey, Washington, D.C., Chicago, and San Francisco. Today there are 11 national NAPs and several regional NAPs formed by the national Internet Service Providers.
As also shown in Exhibit 11, consumers can send signals to a local ISP through several possible communication "pipes": 56K, DSL, wireless, cable, satellite, or fiber. This "pipe" is always narrower than the pipes that move from the local ISP to the regional ISP, or from there to the national ISPs. Signal capacity must increase as one moves from the residence to the Internet backbone. Anything less would produce bottlenecks and delays.
Another way to put this is to say that the Internet is only as fast as its slowest link. Many observers call the final connection from the local ISP to the home "the last mile." For most residential consumers, this is why Internet access is slow, and why broadband needs to be brought to rural America. (It is also worth noting that the Internet can slow down anywhere in the system. If the Internet is a superhighway, experiencing it at different times can be like the difference between riding at high speed on an open road and being on the Washington beltway during "rush" hour. The latter is not high speed.)
The user's modem sends data to modems at the ISP. ISPs appear to have one modem for about every 7-12 customers. This decreases the chance that the consumer will get a busy signal when dialing up. That message is routed up the Internet chain until the final destination is reached. It can be transmitted over one of several Internet backbone systems.
This communication is done through the use of Internet Protocol numbers. These IP numbers are assigned to every computer on the Internet. When users dial into an ISP, they are randomly assigned a ten-digit number. For example, 123.456.789.0 may be the number identifying your computer the next time you log on.
When a user sends an e-mail, the message can take an almost infinite number of routes to the receiver. For example, a user in New York sends a photo of her new baby to her parents in Houston. The e-mail leaves the user's computer in hundreds of pieces. These are known as "packets". To send the e-mail as one block would be too much for the Internet to handle. The packets are created by the modem. The packets arrive at the ISP. From there, each packet is sent onto the Internet. Each packet finds its way to the recipient by looking for the SMTP address. SMTP, or Simple Mail Transfer Protocol, is the language used by ISP servers and routers to designate where e-mail is to be sent. Each ISP has a unique SMTP address and each ISP customer has a unique e-mail address on that SMTP server.
It is impossible to tell where the packets go as they make their way to the receiver because the packets take the path of least resistance. If there is a great deal of Internet traffic in the Washington D.C. area. the packets will avoid it and find alternate routes. Each packet could take its own unique route to the receiver. Eventually, the packets arrive at the ISP of the grandparents in Houston where they are reassembled and can be downloaded the next time the e-mail is checked. The entire process can take as little as a few seconds or as long as a day. Typically, it takes less than five minutes.
The ISP also plays an important customer service role. The ISP should have a staff that is able to answer questions from the most basic ("How do I save the Internet to a floppy disk?") to more advanced ("Flow can I configure my Eudora Pro e-mail software to have more than one account?").
VII. Dial-UP Access
Dial-up service is the most basic way to access the Internet. It involves calling an ISP using a 56K (or slower) modem, and sending the signal over ordinary telephone lines. The modem converts the digital pulses of the computer to the audio frequencies that the telephone system can handle, and then back to digital pulses. The modem is also used to dial the telephone number of the consumer's ISP. The ISP can be a large nationa1 provider such as America Online or Mindspring or one of hundreds of local companies.
The dial-up system relies on the same copper telephone lines that carry voice traffic. The wires are known as twisted pair. One wire is the ground and the other is the live wire carrying voice or data. Users in remote areas may suffer from slower speeds because the telephone system, often referred to as POTS, (plain old telephone system), is not capable of handling the increased traffic. Some wires are older and have deteriorated over time.
Most computers today come with a modem pre-installed to access the Internet using a dial-up connection. Basic modems vary in speed from 14.4K (14,400 bits per second) to 56K (56,000 Bps). In the past 2 years, 56K modems have become standard, but many older computers have slower modems.
Dial-up service through an ISP is available in most parts of the country. In some areas, users may be required to dial a toll number and incur long distance charges to use the Internet. A toll charged is incurred when the ISP does not have a local Point of Presence (POP) in the caller's area. The Point of Presence is the telephone number that users dial in order to gain access to the ISP. The POP does not have to be in the same building or even the same city as the ISP's servers, routers and other hardware. Large ISPs can have dozens or hundreds of POPs that relay calls to the ISP's servers.
A person using dial-up can access any web page on the Internet. However, because dial-up operates at levels that allow data to be transferred at speeds no greater than 56,000 bits per second, many Internet applications cannot be used efficiently, or at all. For example, to watch live video of the U.S. Senate at http://www.c-span.org/watch/ over a 56K modern, you likely would receive a choppy video picture and poor audio. The same signal with any of the broadband connections will show a dramatic improvement.
The cost of dial-up access through an ISP ranges from approximately $15 - $30 per month.  Typically, ISPs offer users unlimited access to the Internet. (In the early days of the Internet, many ISPs charged by the hour.) Consumers generally receive at least one e-mail address and sometimes they receive space on the ISP's web server (a computer that contains a web site's files and makes them available to web users who wish to see them) to make their own web sites.
VIII. Broadband Technologies
Broadband is an ambiguous term with no official meaning. According to the Federal Communication Commission, it is any connection that allows 200,000 bits per second (200K) of information to be sent to a users computer from the Internet Service Provider (referred to as "downstream") or from the user's computer to the consumer's Internet Service Provider (referred to as "upstream.")
For the purposes of this Primer, "broadband" refers to any technology that allows a user to connect to the Internet at speeds faster than a 56K modem and can be connected to the Internet 24 hours a day without prolonged interruptions.  Although 56K is not available in every part of the country, we assume that it represents basic Internet access, and that broadband is anything faster.
There are seven broadband technologies that we will review. They are shown in Exhibit 12, with downstream access speeds. While these technologies make the same general promise-- faster and more reliable access to the Internet-- they vary in the method and speed at which this is accomplished. Overall, there are two approaches to broadband access:
* Technologies that augment or enhance existing 56K access, such as DSL or ISDN. These technologies "enhance" dial-up access lines and allow users to send and receive data at higher speeds than 56K.
* Alternative technologies that bypass traditional 56K telephone lines. These alternatives include geo-synchronous satellites paired with earth-bound uplinking and downlinking technologies, low earth orbit satellites, terrestrial wireless microwave systems (e.g., MMDS, LMDS), T-Carriers, cable, and fiber optic.
These broadband technologies are described below.
1. Digital Subscriber Line (DSL)
DSL is one of the two most commonly used broadband technologies, and it is the primary technology for enhancing existing 56K telephone lines. It is offered as a service by many (but not all) local telephone companies.
DSL uses a coding system to transform ordinary phone lines into high-speed digital lines by compressing signals, allowing them to be transmitted at a significantly higher speed than dial-up. It does this without interfering with regular phone service. Users can simultaneously talk on the phone while surfing the net. It is estimated that there are about 2 million DSL subscribers, almost all of them in urban areas who live or work in close proximity to a telephone "central office."
The local telephone provider must install a DSL Access Multiplexor (DSLAM). The "central office" is a switching station, not necessarily the administrative office of the phone company. It is the facility that bridges the consumer lines with those that go to the national network. The DSLAM allows the phone line to carry voice and data at the same time. It allows data traffic to be carried at download speeds of up to 1,500,000 bits per second (1.5 Mbps), and it can transmit data at 500,000 bits per second (500 Kbps). 
DSL uses a telephone line to access the Internet in much the same way as a traditional analog modem. Unlike the analog modem, DSL is a constant connection to the Internet. It is always on, so users don't need to dial any numbers to connect to the Net. And unlike cable modems, a DSL line establishes a connection to the Net that is the user's alone and isn't affected by how many other people are using the wire.
A problem with DSL is that its signal can extend only 18,000 feet (about 3.5 miles) from the central office. This is a significant impediment in many rural areas. Also, according to some observers (including the Wall Street Journal), many phone companies have problems in installing and maintaining the lines, which require special procedures. It can also be expensive and tricky to set up DSL service for multiple PCs in a home or business.
Consumers of DSL can expect to pay an up-front charge of approximately $100 - $200. This includes the DSL modem and installation. Monthly charges range from approximately $40 to $200 depending on the desired Internet speed. (DSL comes in different varieties: ADSL, RADSL and IDSL. See the related sidebar for a description of DSL types.).
2. Integrated Service Digital Network (ISDN)
ISDN is another technology that can be used to augment existing 56K telephone wires. Like DSL, it is a complicated technology that augments dial-up service in order to provide high-speed digital transmission of both voice and data. An ISDN network integrates voice (analog) data with digital data from the Internet over the same network by creating two channels over a single twisted pair telephone line. One channel carries data, voice, fax, or video signals, and the other is used by the phone company to identify whether the information being sent over the wire is data or voice. Channels can be combined to provide a high-speed connection to the Internet or to support video conferencing applications. ISDN is capable of transferring information from the Internet at speeds ranging from 126,000 bits per second (126 Kbps), for the basic service, to 1,472,000 bits per second (1,472 Kbps) for advanced ISDN services.
Business consumers make up the bulk of ISDN subscribers. Connecting ISDN to a personal computer requires a network terminator and an ISDN terminal adapter. The network terminator is where the line from the ISDN provider enters the consumer s computer. From there, the wire is sent to the terminal adapter, which is the modem in this installation. The terminal adapter is also the device that allows the same wire to be used to receive telephone calls or faxes.
ISDN service is offered by many local telephone companies. The telephone company achieves high rates of data transfer over copper wire by combining wires to act in unison. Wires are "bonded" together in order for many different wires to act as one. When two wires (or channels as they are called in an ISDN installation) are combined, speeds increase to 128,000 bits per second. ISDN can support a maximum of 23 channels being combined to form a system that can operate at a maximum speed of 1,472,000 bits per second.
3. Cable Modem
The most widely used broadband technology involves accessing the Internet via the same wires that bring cable television into the homes of consumers. The signal travels over coaxial cable, which is capable of carrying more data than telephone lines. Coaxial cable is a high-capacity cable used in communications and video. It contains an insulated solid or stranded wire surrounded by a solid or braided metallic shield, wrapped in a plastic cover.
The cable was originally designed for one-way communication. New routers and other equipment installed by cable companies allow two-way communication. This two-way communication ability is what allows cable to be a broadband Internet solution.
Currently, local cable companies are the only providers of this service. Nationally, there are two major cable ISPs: Excite@Home and RoadRunner. Local cable operators partner with one of the two companies to bring the service to consumers. Both systems use their own browsers and offer unique content that non-users cannot access.
The coaxial wire that cable uses can hold tremendous amounts of information, but only over short distances without significant signal loss. Cable systems that have been upgraded to provide broadband service can only do it for about 2,000 feet from the node without losing television signal quality. (Compare this with DSL, which can send signals about 18,000 feet from the central office.)
The node is the point at which the cable operator's main lines enter a neighborhood and branch off into coaxial cable. Typically, a node serves from about two-hundred to one-thousand households. To ensure signal. integrity, cable operators install amplifiers every 2,000 feet. However, after eight amplifiers, television signals begin to become fuzzy due to interference from the amplifiers. That gives cable a maximum range of about 16,000 feet from the node.
Cable's other weakness relates to its ability to carry data. While it is one of the fastest services currently available with possible download speeds of 27,000,000 bits per second (27 Mbps), it suffers from a feature that other technologies do not. The more people using the service, the slower it becomes. Coaxial wire can only hold a limited amount of data. When that limit is reached and additional people attempt to use the Internet, they will all experience slower service. For that reason, individual cable operators have installed "virtual speed bumps" that limit the speed at which users can download and transmit data. Typically, download speeds range from 1,000,000 to 2,000,000 bits per second (1 to 2 Megabits per second) downstream and less than 1,000,000 bits per second (1 Mbps) upstream.
The monthly and up-front costs for cable Internet access are higher than that of dial-up service. Typically, a consumer can expect to pay approximately $200-400 for installation of the cable modem and equipment. Most systems appear to have proprietary modems that must be purchased from the cable provider. Monthly costs are approximately $40-50 for the home user.
4. Satellite Service
Consumers today can receive high-speed Internet service via satellite. The consumer must have downlinking equipment that is pointed to a specific satellite that is in geostationary orbit approximately 22,000 miles above the earth. Such satellites have a constant 'footprint'' and remain in the same relative position to the earth.
The satellite sends data to the user's satellite dish at a download speed of approximately 350,000 bits per second (350 kilobits per second), more than 6 times faster than dial-up service. To send information from the user s computer, users must use dial-up service since direct satellite uplinking technologies are not yet generally available on a commercial basis (but they may become available soon). (See Exhibit 13 for an image of how this works.) Hence, satellite-based Internet service bypasses dialup service when moving downstream from the satellite to the user, but uses dial-up service to send signals to the Internet. About 100,000 Americans access the Internet through this technology today.
One large satellite ISP is DirecPC. This is a subsidiary of Hughes Network Systems, the company that provides DirecTV service. The same dish can be used to access both services at the same time. For DirecTV consumers, start-up costs are about $200 for the modem, and about $30-40 per month for the subscriber fee. The satellite dish can be purchased from a number of retailers.
T-Carriers are a family of technologies that require the use of a dedicated digital communications line and specialized computer equipment at both the user's site and at the site of the company that provides the service. T-Carrier service may be provided either by local or long distance telephone companies or by the Internet Service Provider. The user must have a dedicated computer to manage the flow of data coming in and to route it to other computers for processing. Basic T-Carrier service is called T-1, and faster applications are called T-2 and T-3.
DSL and ISDN use standard 56K twisted pair lines and specialized equipment to send signals at higher frequencies. They are "party line'' technologies in the old sense of that phrase. In contrast, T-Carriers use dedicated lines that can be either twisted pair (in some TI applications), or fiber (for T2 and T3 applications).
For the system to be reliable, a SONET ring must be installed. SONET (Synchronous Optical Network) is a universal computer system that all high-speed digital traffic uses. SONET provides a standard interface so that all systems are able to connect to one another. For example, without SONET technology the Internet backbone system of AT&T could not transfer data to the backbone of MCIWorldcom, or vice versa. The SONET ring is composed of several of these systems that act as redundancies in case of failure. This ensures that the Internet Backbone is never disabled.
All of this technology is needed for the T-Carrier lines due to the amount of data that they are capable of carrying. Many ISPs use T-Carrier lines to provide access to the Internet for their consumers. While the ISP may not offer a T-carrier as an option for consumers, the ISP uses it to transfer their customers signals to a regional ISP.
A T1 line uses four twisted pair wires that contain 24 channels capable of transferring data at 64,000 bits per second (64 Kbps). These channels may be combined to increase the speed of information transfer. If all 24 channels are used together, a T1 line can transfer data at 1,544,000 bits per second (1.544 Mbps).
A T2 line increases the amount of channels to 96. This gives the T2 a maximum data transfer rate of 6,312,000 bits per second (6.312 Mbps). T2 connections and higher must use a fiber optic cable in order to operate at these high rates of data transfer.
T3 is the fastest T-carrier line and often used for Internet access. It contains 672 channels and has a maximum data transfer rate of 44,736,000 bits per second (44.736 Mbps).
The cost of a T-Carrier line depends on the distance the line must travel. Unlike dial-up access, cable or DSL, a T-Carrier is not just a plug-in technology. Switches, bridges and routers are required to configure the channels, to transfer data from the T-Carrier line to the computer network and to direct the data to the right destination. All of this equipment takes a specialized staff to ensure that the system works as designed.
6. MMDS/LMDS Terrestrial Wireless Service
Terrestrial wireless is an important technology that allows users to send and receive Internet signals using a land-based system similar to that used by cellular telephones. All versions of wireless service work on the same principal. Signals are sent from a transmitting tower to an antenna on the recipient's home for a fixed wireless system. (This compares with mobile wireless systems that send signals to the recipient's cell phone or laptop, which is discussed in the sidebar). Two technologies capable of delivering broadband are known as Multipoint Multichannel Distribution System (MMDS) and Local Multipoint Distribution System (LMDS). Both systems use microwave towers that were originally designed to deliver television signals to consumers.
For MMDS to work, consumers must have a line-of-sight path to the tower, and signals can be effectively received within a radius of approximately 20 miles in any direction. Factors limiting the distance include the curvature of the Earth, height of the tower, hills and tall buildings.
Users need not only a modem but also a digital transceiver, which is the antenna that receives the signal. MMDS is faster than DSL. Current downstream speeds are near 5,000,000 bits per second (5 Mbps) and upstream transmissions are rated at 256,000 bits per second (256 Kbps).
LMDS is another fixed wireless system and works in much the same way as MMDS. It operates at higher radio frequencies, which allow for very clear signals and an ability to handle millions of bits of data. LMDS can transfer 150,000,000 bits (150 Mbps) of data per second into and from a user's computer. However, operating at these frequencies diminishes the effective range of the signal. A user can be no more than approximately four miles from the transmitter tower. This limits application to denser urban areas.
7. Fiber Optic Cable
Fiber optic cable uses light waves sent through small glass tubes to carry information from one point to another. It currently represents the ultimate in high-speed Internet access. Devices located at each end of the cable convert the digital signal into light and then back to digital. Information can be anything from TV signals, voice, live teleconferences, data, or Internet web sites.
Fiber optic cable was developed to carry signals hundreds of miles without the need for signal boosters and without loss of signal strength or integrity. This is why the long distance telephone network relies almost exclusively on fiber optic cable to transmit calls.
In the last few years, Regional Bell Operating Companies (RBOCs) and other telecommunication companies have begun to install fiber on the local level. In addition, the national network of wires that carry cable television signals use fiber optic cable. It is not until the signal reaches the neighborhood level that the signal is transferred to coaxial cable to be delivered to consumers.
Fiber optic cable can transmit information to and from the Internet at speeds measured in millions of kilobits per second. The national fiber optic network has almost an unlimited supply of capacity.
Fiber may be used in two ways on the local level. The first is known as "fiber to curb." This occurs when the local company installing the cable runs the fiber within 1,000 feet of a home. The wire from the curb to the home and inside the home is the traditional twisted pair copper wire. Tests of this installation method have shown that the fiber could carry data at 52,000,000 bits per second (52 Mbps). That is fast enough to view any type of video over the Internet, download any file found on the Internet almost instantaneously, and receive telephone and cable television service.
"Fiber to home" is a system in which the fiber optic cable is extended into the home and is used as the telecommunication wiring throughout the structure. In this installation, there is no need for twisted pair or coaxial cable. With a 100% fiber installation, Internet transfer rates jump to millions of kilobits per second.
The connectors which attach fiber cable to transmitters, receivers, and other fiber must provide a near-perfect interface, with little room for error. To a light wave traveling along the cable, a gap the size of a human hair at a connector is a major obstacle. Fiber optic cable is wrapped in five layers of protective material to prevent damage from weather or abuse. This adds to the cost and time it takes to deploy the cable.
Although initially expensive, many cooperatives are installing fiber optic cable or participating in local projects with other providers. Some cooperatives are connecting their headquarters, district offices and substations with a fiber link to improve utility operations and communications. For example, a fiber link could allow every district office to have ultra-high speed access to a single customer database. The same link could then be used for other e-commerce applications. Some of this investment can be recovered by selling excess capacity (which is almost unlimited) to local businesses.
We have reviewed a number of technologies that may be utilized to deliver broadband access to rural America, including to electric cooperatives. These technologies either augment existing twisted pair lines (like DSL or ISDN), or bypass lines by using other technologies, such as cable, satellite, or MMDS. Each of these technologies has strengths and drawbacks.
We anticipate that cooperatives will continue to investigate all of these technologies, and others that may yet be developed. As noted above, many cooperatives are already involved in important projects involving fiber, MMDS, DSL, and others. We also anticipate the increased use of satellite applications.
There may be no single broadband technology that will be ideal in all situations. As shown in Exhibit 14, cooperatives may install (or be involved with) a number of different broadband technologies. What ultimately matters is that cooperatives are able to connect all of these approaches, and that consumers have high-speed Internet access.
X. Conclusion: The Value of the Cooperative Network
There is one other broadband issue to discuss. Electric cooperatives serve over 30,000,000 Americans in 46 states. Collectively, they represent the largest electric utility network in the United States.
Electric cooperatives have long constituted a network in the sense that they have cooperated and worked together to achieve common goals, Co-ops are famous for providing mutual aid when one or more suffers a storm or comes under attack from a predator utility. Comparably, co-ops have worked together for legislative or regulatory solutions that are best for the network and end-use consumers collectively.
The issue of broadband now brings this discussion to a higher level. The network can become networked. Through broadband technologies, co-ops will not only be able to work together, they will be able to communicate and share information instantaneously. They will be able to coordinate purchasing activity and immediately lower the total amount spent on materials and supplies. They will able to achieve cost economies by handling medical, retirement and personnel information electronically. In fact, cooperative.com is being developed as a business telecommunications platform that will help make these things happen.
Broadband technologies may soon allow for digital meetings and eliminate the need for some travel. Web-based training is clearly on the horizon. Broadband may have applications that enable co-ops to respond to the increasing volatility in the wholesale electricity market. The opportunities, like broadband's own capacity, are almost unlimited. There are still obstacles to bringing broadband to rural America, but those obstacles will be overcome.
Greg Boudreaux is NRECA's Senior Adviser to the CEO for Member Eduction. Prior to joining NRECA, Greg was an assistant dean of the graduate school at the University of Maryland and a resident graduate professor for the University of Maryland in Tokyo, Japan. Boudreaux, holds a master's degree from LSU and a doctorate from Duke University.
Brian Sloboda is a Research Associate in the Education & Training Department at NRECA. Brian is a 1997 graduate of Fairmont State College with a degree in Speech Communication and in Political Science.
(1.) "Advanced Telecommunications in Rural America: The Challenge of Bringing Broadband Service to All Americans," April, 2000.
(2.) In everyday use, factors such as distance from telephone switching stations, time of day, line quality, and others affect Internet speed.
(3.) When discussing the size of a computer file such as a picture or Word document, the term byte is used to refer to file size. When referring to Internet speed the word bit is used. They refer to files that are the same size. A file that is 56 kilobytes in size would take 1 second to transfer via a 56 kilobit per second modem. The reason for the difference is that different groups wrote the standards for computer storage and for the Internet. Otherwise, they refer to the same thing.
(4.) For a complete list of National Backbone providers and ISPs in the United States visit www.boardwatch.com.
(5.) All ISP and broadband costs identified in this Primer are approximate at best. And as evidenced by other technical areas, they are also likely to change quickly in response to competitive forces or new technologies that enter the market.
(6.) Many traditional Internet Service Providers do not allow dial-up customers to remain constantly connected to the service without data being transmitted back and forth. The reason is that if all of the ISP's consumers did this, there would not be enough lines for everyone to use. An ISP may have 5,000 consumers but have the capacity for only 1,000 to be on-line at any one time.
(7.) These speed measures are ideal. DSL providers appear to install electronic "speedbumps" to manage their systems. As a result, actual DSL download speeds are in the 100,000-200,000 bits per second range, and typical uploads speeds are in the range of 64,000-250,000 bits per second.
FILES VS. BITS
Computers exchange bits. Users exchange files- actual documents, pictures, charts, videos, songs, and other complex combinations of data that have meaning for humans. Because so many files are exchanged over the Internet, a new "file language" has developed to show how such exchanges are actually performed.
Any file on a computer can be e-mailed to or downloaded from a web site. The most common file types to download or send via e-mail are application files, executable files, picture files, and zip files.
Application files are items such as Word Documents or Excel spreadsheets. They are the documents that most computer users create with software packages such as Microsoft Office.
Application files do not operate on their own. Instead, they need a piece of software known as an executable file to open, edit and view it. Executable files are the actual programs that a computer uses to do things such as install software or make application files. For example, when a user opens Microsoft Word, he or she is actually opening a file named "world.exe." The ".exe" extension on a file identifies it as an executable file.
Picture files sent via e-mail are in either .jpg, .gif, .tif, or .bmp format. The formats deal with the quality of the picture, size of the file, and what can be done with the picture. Each format has its own pluses and minuses. Typically, a .tif file will be larger in size and more detailed, and are only used when a high resolution picture is needed. The higher the resolution, the better the clarity.
Formats commonly found on web pages are .jpg and .gif. These are smaller in size and consequently take less time to download. The quality is acceptable for most uses. A .bmp or bitmap is a file type not commonly used on web pages as they tend to be larger in size to the .jpgs or .gifs. Any picture on a web site can be saved to a user's computer by right clicking and choosing "save picture as."
Zip files are files that have been compressed to decrease file size. They can install software onto a user's computer or can be used to send several documents in one easy-to-use package. A zip file is like a suitcase. You can stuff many items into it and when it comes time to close it, everything is compressed. To open or create a zip file a user must have a zip utility such as Winzip or PKZip.
SPEED CONVERSION CHART
1 bit is a single digit of a binary number. Either 1 or 0.
1,000 bits = 1 Kilobit = 1K
1,000 Kilobits = 1 Megabit = 1M = 1,000 K
1,000 Megabits = 1 Gigabit = 1G = 1,000 M
1,000 Gigabits = 1 Terabit = 1T= 1,000 G
DSL types can be categorized as Asymmetric or Symmetric. Asymmetric DSL features a fast rate transfer from the Internet but a slow speed when sending out data. Symmetric DSL has the same rate transfer speeds upstream and downstream.
ADSL- Asymentric DSL allows voice and data to share the same line at the same time. This is accomplished by sending data at a higher frequency than the voice communication. A device called a splitter is installed at the user's end. The splitter separates the two frequencies and allows voice traffic to go to the phone or fax and data traffic to the computer. Versions of ADSL known as "lite" allow residential users to use a filter instead of the expensive splitter to separate the signals. Consumers must be no more than 18,000 feet from the provider's central office.
RADSL- Rate Adaptive DSL works in the same manner as DSL. However, it is able to adjust speed based upon signal quality. This helps to optimize the capabilities of the network. Users can be up to 25,000 feet from the central office.
VDSL- Very High Bit Rate DSL is the fastest of all DSL technologies with a downstream rate of ranging from 13 Mbps, when within 5,000 feet of the central office, to 52 Mbps, when 1,000 feet from the central office.
HDSL- High Bit Rate DSL is a symmetric version of DSL. This gives it the advantage of having the same rate of data transfer upstream and downstream. The user must be within 12,000 feet of the central office instead of 18,000 feet for ADSL.
SDSL- Symmetric DSL is a variation of HDSL that adjusts speeds based upon line quality.
IDSL- ISDN DSL is the slowest of all technologies at a transfer rate of only 144 Kbps but does allow the user to be 26,000 feet from the central office.
LOW EARTH ORBIT SATELLITE SYSTEMS
Although not currently available, reference should be made to a new technology known as low earth orbit. As the name implies, these satellites will fly lower than geostationary satellites at approximately 930 miles above the earth. Because of the lower orbit, they are not geostationary, which means that there must be a larger set of orbiting satellites which are networked together to provide continuous service. Any single satellite is in view (i.e., maintains a specific "footprint") for only a few minutes. In order to maintain continuous communications, several satellites must be used.
Teledesic Corporation has developed a system that it claims will use 288 satellites in low earth orbit. This would give them complete coverage of the globe. According to the Teledesic web site (www.te1edesic.com) "customers will obtain two--way, broadband access to the Teledesic Network through compact user equipment mounted on the roof of their office, home or school. No ground-based infrastructure is necessary, so Teledesic is a last-mile/kilometer (or first-mile/kilometer) solution that can work anywhere in the world." The combined signal could carry 30,880,000,000 bits of data per second. The project is projected to be operational in 2004 at a cost of $9 billion.
If this system performs as promised, it could be a viable solution to the lack of broadband access in rural areas. Electric Cooperatives should follow the development of this and other technologies. Notice also that Teledesic is promising broadband speeds that dwarf other technologies, with the exception of fiber.
MOBILE WIRELESS PCS
Mobile, wireless Personal Communications Systems are currently being promoted, but technically speaking are not broadband technologies, and do not currently bring the full. capabilities of the Internet to users. (Some have called this service "Internet-lite.")
The required infrastructure includes a tower placed on top of a tall building or hillside. Fixed (e.g, MMDS, LMDS) and mobile (PCS) systems vary in the speed at which they deliver Internet content. Mobile wireless technology eliminates the need for special cables, routers or amplifiers. One of the first wireless technologies was Cellular/PCS dial-up. This non-broadband technology uses the same system that cell phones use to send and receive signals.
Typical uses are for laptop computers and for so-called Personal Digital Assistants such as the Palm Pilot. Cellular dial-up transfers data at 9,600 bits per second (9.6 Kbps). This is five times slower than a 56K dial-up connection, which is why in its current applications, PCS can only deliver basic data (e.g., sports scores, movie times) and not the colorful graphics or detailed information available over the Internet through broadband applications.
GLOSSARY OF TECHNOLOGY TERMS
analog: Not digital. Analog describes a way to transmit or measure data in terms of continuously varying physical qualities--as with the shifting hands of a grandfather clock.
ASCII (American Standard Code for Information Interchange): The standard, unformatted 128-character set of letters and numbers that can be represented by a seven-digit binary number between 0000000 and 1111111.
Baby Bells: Sometimes referred to as regional Bell operating companies or RBOCs, the Baby Bells were created by the breakup of Ma Bell in 1984.
backbone: The main conduit of a computer network, to which all other users and networks connect. There are only a handful of major backbones today, and the top two--MCI Worldcom and SprintLink--handle close to 75 percent of Internet traffic.
bandwidth: the maximum rate at which information can be pushed through a network. Most modems run at 56Kbps; ISDN lines run at 128Kbps; a T1 line provides 1.5Mbps of bandwidth. Bandwidth is also an internal computer issue, as in the speed at which a processor can talk to memory.
baud: A speed of data transmission, pronounced "bod."
binary: The essential adjective of the 0 or 1, on or off, black or white world of computing. A binary or base-two number system represents data in 0s or is. Computers are electrical machines and recognize only the existence or nonexistence of electric current. Charge, no charge. One, zero.
bit: The smallest unit of digital information; a binary digit, either 1 or 0. Generally used to describe transmission speed.
byte: A collection of bits, usually 8 bits in length. Bytes, therefore, range from 0 to 255. Generally used to describe storage capacity.
bps (bits per second): This measurement of the speed at which data is transferred is the mph of the Internet. Variants include Kbps (kilobits per second) and Mbps (megabits per second).
broadband: An adjective that comes from the telephone world, where it refers to wider bandwidth than a standard telephone line. In the popular press, broadband is a synonym for high bandwidth.
cable: Wire that dwarfs the capacity of copper. Installed originally to deliver cable TV, cable is often used as a synonym for that service.
CLEC (competitive local-exchange carrier): Pronounced "sea-leck." After years of market dominance, the ILECs--incumbent local-exchange carriers like regional telcos SBC and Bell Atlantic-- are under pressure from upstarts entering the market with advanced data and broadband services.
client/server: An adjective describing the network architecture in which a powerful, central computer (server) accepts requests for resources and services from many individual PCs (clients).
coax: Short for coaxial cable, the standard cable TV wiring.
common carrier: A private company that offers telecommunications services to the public.
compression: A method to store text, data, sound, or images in fewer bits. Rather than store every pixel of a blue square, the computer might store one blue pixel and the dimensions of the square. Compression is carried Out by any one of many compression standards: AU, GIF, JBIG, JPEG, MPEG, MP3, PICT, SIT, TIFF, ZIP.
cookie: A unique identifier sent to your computer by a Web server and stored on your hard disk. As a verb, the term refers to tagging users' browsers in order to monitor their browsing.
digital: A description of data which is stored or transmitted as a sequence of discrete symbols from a finite set. Most commonly this means binary data that is represented using electronic or electromagnetic signals. The opposite of digitalis analog.
Digital Subscriber Line (DSL): Also known as Digital Subscriber Loop. A family of digital telecommunications protocols designed to allow high-speed data communications over the existing copper telephone lines between end-users and telephone companies. The first technology based on DSL was ISDN, although ISDN is not often recognized as such nowadays. Since then, a large number of other protocols have been developed, collectively referred to as xDSL, including HDSL, SDSL, ADSL, and VDSL.
FCC (Federal Communications Commission): The FCC was created by the Communications Act of 1934 to police the airwaves.
fiber optics: A communications technology that sends electromagnetic signals down cables made of glass or plastic fibers.
56Kbps (56 kilobits per second): The data capacity of a normal single-channel digital telephone channel in North America. The figure is derived from the bandwidth of 4kHz allocated for such a channel and the 16-bit encoding (4000 x 16 = 64000) used to change analog signals to digital, minus 8000 bit/s used for signaling and supervision.
gateway: A translator machine or router that links networks speaking different protocols.
GIF (graphic interchange format): A compression format used for images.
host: A computer on a network. This is almost a synonym for "node," but it generally implies that the machine is a normal computer (most commonly a server) and not an infrastructure device (such as a hub or firewall).
HTML (hypertext markup language): The formatting lingo of the Web, HTML lets humans talk to Web servers and browsers. HTML is spoken in tags--short commands such as [less than]HI[greater than] that surround pertinent text like quotation marks.
HTTP (hypertext transfer protocol): The original communications protocol of the Web. Browsers use HTTP to connect to Web servers and servers use HTTP to talk amongst themselves.
hypertext: A system of linking electronic documents.
Integrated Services Digital Network (ISDN): A set of digital telecommunications standards allowing a single wire or optical fiber to transmit voice, digital network services, and video data up to 128 Kbps.
interface: The physical piece of hardware which does the actual transmitting and receiving of network data.
modem: A piece of hardware that allows computers to talk to each other by transmitting digital information into analog signals that can be sent over regular phone lines and redigitized at the receiving end.
node: A device on a network. Nodes can be personal computers, servers, printers, modems, or infrastructure elements (routers, switches, etc). In essence, a node is any machine that can actively participate in the exchange of information on the network (cables, for example, are not nodes).
operating system: The underlying software that give a computer its look and feel and upon which all other applications and hardware depend.
optical fiber: A plastic or glass (silicon dioxide) fiber no thicker than a human hair used to transmit information using infra-red or even visible light as the carrier (usually a laser). Optical fiber is less susceptible to external noise than other transmission media, and is cheaper to make than copper wire, but it is much more difficult to connect. Optical fibers are difficult to tamper with (to monitor or inject data in the middle of a connection), making them appropriate for secure communications. The light beams do not escape from the medium because the material used provides total internal reflection. A single fiber can transmit 200 million telephone conversations simultaneously.
packet: A small stream of information, including the information necessary for delivering it. In the TCP/IP world, a packet includes the datalink address of the device which issued it, a source network address, a destination network address, the datalink address of the device to which it is headed next, a service number, and the payload data.
pixel: The shortened form of picture element, for dots that make up an image or character on a computer or TV screen. The more pixels, the better the resolution.
POP (point of presence): Informal jargon for local access to a network or telecom service.
portal: The welcome mats of the Web. These vast sites lead the way to the Net for millions who use the proprietary interface, channels, and search technologies to find news, entertainment, or other information. The largest portals include Yahoo!, Excite, Lycos, AOL, and MSN.
protocol: Protocols such as HTTP, IP, PP, and TCP are sets of rules governing the exchange of information. Computers use these rules to communicate with other computers, printers, and modems. Protocols are used to control when a node on a network can transmit, the format of transmissions, addressing rules, methods of data delivery, and virtually every other aspect of computer communications.
Public Switched Telephone Network (PSTN): The collection of interconnected systems operated by the various telephone companies and administrations. Also known as the Plain Old Telephone System (POTS) in contrast to xDSL and ISDN.
router: A machine that forwards packets between different networks on the basis of source and destination addresses. Routers maintain lists of paths to networks (called "routing tables"); these often include a "default route," to be used when a more specific route is not available. Considered the traffic cop of networking.
search engines: Search engines help Net users target information by keyword or concept. Unlike database searches such as Lexis-Nexis and Dialog, search engines are free as long as you have Web access.
server: A computer or workstation that "serves' stored data and files or processing power to other machines--or "clients"--on a network.
SMTP (simple mail transfer protocol): The language computers must speak to send and receive email on the Internet. SMTP is used in conjunction with another protocol that downloads incoming messages or stores them on the server.
spider: Search engine technology. A simple program that scans the Web, crawling from link to link in search of new sites and recording the URLs.
T-1: A digital carrier facility used to transmit a DSI formatted digital signal at 1.544 megabits per second. Although some consider T-1 signaling obsolete, much equipment operates at the "T-l" rate and such signals are either combined for transmission via faster circuits, or demultiplexed into 64 kilobit per second circuits for distribution to individual subscribers. T-1 signals can be transported on unsheilded twisted pair telephone lines. A T-l circuit requires two twisted pair lines, one for each direction. Originally a backbone technology, T1s now carry data and voice for most medium-sized businesses. The T-1 designation refers to the signaling speed rather than the medium of the network (copper, fiber).
uplink: To transmit a signal from a ground station to a satellite.
upload: To transfer a file from a PC to a server, on a network or on the Net.
URL (uniform resource locator): The address of a page on the Web.
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|Author:||Boudreaux, Greg; Sloboda, Brian|
|Date:||Sep 22, 2000|
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