Telecommunications, Wireless

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The explosion of digital technology in the late 1990s began what came to be known as the information age. An important change that was made possible by digital technology was the switching of many kinds of communication from wired devices to wireless devices. Two types of wireless devices have come to the forefront during the digital age: radio-frequency (RF) devices and infrared-emitting (IR) devices.

IR devices are used mainly for indoor applications. In order for an IR device to work, both the transmitter and receiver must "see" each other. The television remote controls that most Americans have in their homes are IR devices. Several companies developed IR devices that do more than change the channel of the television. IR devices can transport video, audio, and data, and they can control functions at amazing speeds.

The infrared light that IR devices use to transport data is long-wavelength light that is beyond the range of human vision. These devices work by sending the digital data, the 1s and 0s, via flashes of light. A flash within a digital word is "on" or "yes," whereas no flash within the same word is "off" or "no." By counting the flashes and non-flashes within a prescribed amount of time, the 8-, 16-, or 24-bit "word" (i.e., byte) can be created. The microprocessor within the receiving device sets the clock speed and decodes the flashes to determine what the user wishes to happen. Computer keyboards, computer mice, digital cameras, and other input devices can use IR to accomplish their mission.

Using RF allows one to travel outside the confines of the home or office. RF signals pass through most walls, work while in motion, deliver more bits per second than IR, and are available almost worldwide. RF can be delivered through transmission towers, satellites, portable transmit-ter-receivers, and even through the leakage from cable television wires. As more and more ways are thought of to transport information, and the importance of people continuously moving from place to place is acknowledged, RF devices will become more prevalent—while IR will supplement other devices.

Traditionally, these services (e.g., audio, video, data, and control functions) were contained in the wired universe. Coaxial cable was the wire of choice for transporting video (e.g., cable television). Twisted-pair copper wire carried voice traffic and fax traffic over the traditional telephone system. Serial cable carried instructions between computers and their peripheral devices. "Fire-wire" came into being in the late 1990s; this hybrid of coaxial and serial cable allows faster transfer of data than either coaxial or serial. Designed for Apple computers, the PC clone computers soon became able to use Fire-wire to operate. Fire-wire found its first niche in the professional audio-video industry. Fire-wire allowed those that edited music and video on their desktops to speed up the transfer from the hard drive to the final storage medium.

Soon thereafter, web-streaming electronics and programs allowed those creative artists to send their creations to others via the World Wide Web. Compression increased the speed of the process and provided a whole new way for listeners and viewers to find their favorite music and video. Just point and click, download, and save, and an individuals could have their favorite music or movie right there on the computer hard drive. One never had to leave home again to purchase entertainment. It was all there, just a mouse-click away.

The computer went wireless too. Wireless modems let web surfers take their laptops with them where they roamed. No more did they have to be connected to a telephone line. All they had to do was power up their modems, dial the number, and they were on the Internet.

The wireless computer uses the same technology as the cell telephone. The cell telephone uses spread-spectrum technology to switch from cell to cell while simultaneously transmitting and receiving.

"Spread-spectrum technology" means that the same device can operate on more than one frequency at the same time. This technology came into being in the 1940s as a way to prevent enemies from jamming the homing mechanisms on U.S. Navy torpedoes. Because the homing device used more than one radio frequency to find its target, the enemy could not confuse the torpedo by flooding one frequency with RF. In order to stop a torpedo, the enemy would have to know all of the frequencies that were being used by the torpedo, in what order the torpedo used those frequencies, and how long the torpedo used each frequency. This was next to impossible.

Cell telephones used the same idea—not to jam enemy torpedoes but to allow a user to travel from one cell to another without losing the telephone call. A cell is just the geographical area that a particular cell tower covers with its three-watt signal. As the user moves beyond the range of one tower, the tower "hands off" the call to the next tower in line that has the strongest signal from the cell telephone. The cells can be thought of as giant invisible circles. If a person stands in one circle, then one tower is used. If the person moves beyond the edge of the circle and enters another circle, then the second tower is used.

The personal communications system (PCS) uses the same technology, only instead of using towers, PCS uses cable television wires and shorter, less powerful one-watt towers to carry a telephone conversation. Digital cable television systems allow many telephone calls to be carried with digital television within the spectrum that is not used by the cable company to carry television. At the cable company office, the call is switched to the traditional telephone company's wires to complete the call.

Satellite telephones work like cell telephones in that they use spread-spectrum technology. Instead of handing off to another tower, the satellite telephone hands off to another satellite. Satellite telephones use low-Earth-orbiting satellites to give the user a dial tone anywhere on the planet. Both the user and the satellites move. As a satellite passes over the horizon, out of "sight" of the telephone, the call is handed off to the next satellite in line. If no satellite is available, then the call is routed through the nearest available cell network. The downside to satellite telephones, at least in the beginning, was the high cost of satellite time. It is expensive to launch and maintain satellites, and this cost was passed on to the user. However, satellite telephones allow one to make calls or to log on to the Internet anytime and anywhere.

All of these devices that had formerly been restricted to wire carriers were liberated by the use of the radio spectrum. However, since the spectrum is used for other purposes, there is less available spectrum for new services. Nicholas Negro-ponte addressed this new problem with what he called the "Negroponte switch."

The Negroponte switch is the change from wired technology to wireless technology and vice versa. Traditional wired services found their way onto the RF spectrum and RF devices went to wires. The Negroponte switch works on one basic principle: "bits are bits." The computer or television or telephone or any other device does not care, nor does it know, what the bits are meant to represent. Any device that can pass digital bits and bytes can pass them along. Only at the final destination do the bits get turned into what they are supposed to be. The most important bits, according to Negroponte, are the "header bits." These are bits about bits. These bits tell the output device what they are supposed to be.

The Negroponte switch deals with voice and data, as well as with the way in which people interface with their devices. "Intellisense" is the word that Negroponte created to describe how all household, workplace, and personal devices will communicate with each other to better serve the needs of people. For example, say that an individual wants to get up thirty minutes later than usual. All that person would have to do is set his or her alarm clock. Intellisense would then tell the coffeemaker, the computer, the water heater, the furnace or air-conditioner, the car, and the telephone that the person will be sleeping for an additional thirty minutes. Once this is done, the telephone will not ring during the additional thirty minutes, the coffeemaker will make coffee thirty minutes later than usual, the computer will download any important information that the person might have missed by sleeping late, and the hot water and room temperature will be at their optimum level thirty minutes later than usual. All of this saves the person both trouble and money. A person does not need a warm house or hot water until he or she is ready to get up and shower. If the person is low on milk, the refrigerator will tell the car to remind the person to get some milk on the way home. Or, if the refrigerator is in need of service, it will call the repair service before it breaks down.

When the person goes to work, Intellisense will know where to route incoming telephone calls and e-mail messages. Instruction manuals will be obsolete. Intellisense will tell people how to operate devices. A person will tell the computer/television (according to Negroponte, there will soon be no difference) what news is important, and the device will "filter" the content to suit the viewer's tastes. People will no longer have to remember to program the video recorder or read the television listings to know when to watch a favorite program. People will be able to watch anything, anytime.

When the Negroponte switch becomes the norm, extremely targeted advertising will come directly to individuals through the program content, but they will not know it is advertising; it will be seamless with the program. An individual will become part of the machine. Electronics will be woven into people's clothing. Dick Tracy's twoway wrist television will become reality. A person's belt will contain the batteries to operate all of his or her gear. An individual will be able to access the telephone, the Internet, e-mail, call home, and program home devices from a distance. The only question is how will those signals be passed along to the chosen destination.

Because bits are bits, all of this is possible. The Negroponte switch will allow those media that were once sent over wires (e.g., the telephone) to be sent over the air. Those media that used to be sent through the air (e.g., radio and television) will soon be sent over wires, similar to cable television.

The problem will show itself soon after the switch begins—there is only so much open spectrum that is available to use for all these devices. One day, the usable spectrum will be exhausted. What then? Negroponte suggests that those things that can use wires should continue to do so and that those things that can only use the spectrum should go wireless.

Spectrum saturation was a problem with early cell telephones, which were analog devices that operated in the 800-megahertz (MHz) range. People who had programmable scanners regularly listened in on conversations that took place over cell telephones. The cell telephone industry went to the U.S. Congress to get laws passed to make it illegal to intercept and eavesdrop on cell telephone conversations. That did not do much for those who already had scanners, nor did it stop others from listening to conversations. In the mid-1990s, the cell telephone industry came out with digital cell telephones. These telephones, which sounded clearer than their analog cousins did, were also harder to intercept. Digital cell telephones use header bits to tell the cell telephone tower who the telephone belongs to, who they are calling, and what is going to be traveling over the signal. Voice, data, or other media can be sent over digital cell telephones with a greater degree of privacy than is available with analog cell telephones because the potential interceptor has to be able to know what "channel" and tower the digital cell telephone is on, along with what the header code is when the conversation is started. Without that information, the scanner is useless. All the listener hears is the digital bits traveling back and forth, not what those bits represent.

Negroponte has stated that as the limited spectrum is taken up by cell telephones, satellite telephones, wireless computers, wireless body wear, and other peripherals, some of these devices will go back to using wires to communicate with each other. Already, the spectrum for pagers and twoway communication (e.g., police, fire, and emergency services radio) is getting squeezed by commercial digital broadcasting and the other users of RF energy. Soon, society will have to find ways to go back to the wired world for those devices that do not need to travel.

These wireless devices give users the freedom to travel about without worrying about missing an important call or message. As with all freedom, a price comes with it. That price is the overflowing river that is the RF spectrum. With the Negroponte switch, all wired services will become wireless and vice versa. The television and the computer will be intertwined into one box. Those individuals who need to be in communication with others all the time will have that opportunity, and they will still be able to roam about outside the home or office. While the "modern" devices will quickly become obsolete, the new ways to communicate and stay in the know have not been thought of yet. One's house and office will know whether one is at home or at work. The building will know where an individual is, where the nearest telephone is located, and what calls an individual must receive. People will program these devices with their voices. The content does not matter. Bits are bits. Only how those bits are moved will change. From an economic standpoint, only those devices that are cheap and easy to operate will survive in this new information age. Consumers will not tolerate anything that is merely an improvement over preexisting technology. Merely redesigning a graphic interface without making it easier or more efficient to operate will not be enough.

Digital devices that bring people information have to be inexpensive, easy to operate, and, ultimately, useful if their creators want to survive in the world of business. Until then, people will use pencil and paper because it is easy. In general, people will watch a fuzzy television and listen to a radio that is full of static because they are more inexpensive than high-definition television and compact disc players. Until the above conditions for digital devices are met, the Negroponte switch will not become a reality.

See also:Cable Television, System Technology of; Digital Communication; Digital Media Systems; Internet and the World Wide Web; Radio Broadcasting, Technology of; Satellites, Communication; Satellites, Technology of; Telephone Industry, Technology of; Television Broadcasting, Technology of.


Dertouzos, Michael L. (1997). What Will Be: How the New World of Information Will Change Our Lives. New York: Harper.

Gershenfeld, Neil A. (1999). When Things Start to Think. New York: Henry Holt.

Negroponte, Nicholas. (1995). Being Digital. New York: Knopf.

Papert, Seymour A. (1996). The Connected Family: Bridging the Digital Generation Gap, with forward by Nicholas Negroponte. Atlanta, GA: Longstreet Press.

Eric E. Harlan