The Wireless World
This is a sample chapter of The Essential Guide to Wireless Communications Applications: From Cellular Systems to Wi-Fi, Second Edition (ISBN: 0-13-009718-7).
By Andrew Dornan
In this chapter...
- Cutting the Cables
- From the 20s to the 2000s
- Buying a Cell Phone
Wireless technology is changing the world. Where communication has hitherto relied on cables strung on poles or dug into the ground, we are now able to send voice and data through air and empty space. Without wires holding us back, we will be able to stay in contact wherever we are. New services can be set up in minutes, without spending months negotiating rights of way or constructing tunnels.
The preceding paragraph could have been written a hundred years ago. At the beginning of the twentieth century, wireless technology also promised to revolutionize communications. It did, but it took many decades before it could be combined with another of the twentieth century's new technologies—telephony. A second wireless revolution occurred in the 1990s as wireless transmitters became small and lightweight enough to be built into hand-held telephones. Rather than simply watching TV or listening to radio, the majority of people in some countries were broadcasting signals of their own.
The effects of this second revolution continue into the 2000s, as both wireless technology and telephony converge with the Internet. The result may eventually be a single network for both voice and data, with wireless as the dominant access method. Most information will still travel over high-bandwidth fiberoptic cables for parts of its journey, but the phones and computers through which people actually interact with the network will not require wires.
|WHAT'S IN A NAME?|
Wireless technology is littered with three-letter acronyms (TLAs). Those that appear in this book are spelled out when first used and sometimes again in later chapters. They are also listed and defined in the glossary.
A few are impossible to spell out; this is because some vendors and standards groups develop a kind of "acronym envy" over the capital letters that acronyms usually use. These people insist that their technologies be capitalized, even though they don't actually stand for anything.
Still more vendors like to take an existing acronym, often one of an official standard, and change or add one letter (often m, for mobile). This is an attempt by companies to differentiate themselves from the competition, but it has the opposite result—many very similar-sounding products or standards.
The situation is further complicated by the way that certain acronyms change over time. For example, the basic cellular standard in the United States is called AMPS, which originally stood for Advanced Mobile Phone System. As technology progressed, it began to seem anything but advanced, so the A changed to Analog. When a digital version was developed, it changed again to the more accurate American. All three are still in use.
The terms cell phone and mobile phone mean almost the same and are often used interchangeably. Technically, cellular is a subset of mobile, but a large one: Most mobile systems are cellular, and all cellular systems are mobile. In general, the British tend to say mobile, whereas the Americans say cell. The industry prefers mobile, because it implies freedom, whereas cell suggests imprisonment. A few companies don't like the term phone, because newer devices are more like small computers. For this reason, they are often referred to as terminals.
One advantage of cellular/mobile telephony is that it can compete with monopoly wireline phone companies. These monopolies are known by a variety of names, not all of them printable, but are officially called Incumbent Local Exchange Carriers (ILECs, or simply incumbents), because they own the telephone exchange. In the United States, they are sometimes called Regional Bell Operating Companies (RBOCs), after the Bell system from which they are descended. In most other countries, they're called Post, Telegraph, and Telecommunications Authorities (PTTs), because they used to be (and in some cases still are) run by the country's Post Office.
CUTTING THE CABLES
The wireless revolution cuts both ways: It changes the Internet and the phone system, but also requires change in the wireless technology itself. Digitization and Internet protocols enable radio to carry much greater amounts of data than its nineteenth-century pioneers thought possible, all personalized for individual listeners. Instead of poor-quality television programs broadcast to everyone, users may eventually have virtual reality on demand.
By mid-2000, more people in Europe had a mobile phone than had a PC or a car. By the end of 2001, the world's most popular online service was one that could be accessed only through a cell phone, not a computer. Analysts predict that the trend will continue, with wireless gadgets overtaking traditional computers as the dominant Internet access means at some point between 2004 and 2006. Unlike the relatively primitive, text-based Internet phones that appeared in 2000, these new gadgets will allow true Web surfing, as well as location-based services and other enhancements that take advantage of mobility.
This shift from fixed to mobile access could have profound effects on the Internet, which, in its early years, was dominated mainly by the wealthy, the young, and the male. That will change: Mobile phones are more evenly distributed across society, and even the cheapest models are beginning to incorporate some kind of Internet access. Though these cost slightly more to produce, operators often subsidize the manufacturing to promote usage.
And wireless technology isn't just for rich consumers in the West. In the late 1990s, cell phones enabled many people all over the world to make their first-ever calls. In the next few years, they will also be sending their first e-mails—again, wirelessly—and probably from something that more closely resembles a phone than a traditional PC. The Web will become truly worldwide.
Most of the excitement is justifiably about mobile wireless, but there are also significant advancements in fixed wireless, which is used to replace local telephone wires. Satellite systems can be either mobile or fixed, with some systems, such as the futuristic Teledesic, planning both. These are aimed both at globe-trotting travelers and at parts of the world that have no communications infrastructure at all. A combination of cellular and satellite technology can often bring telephony and Internet access to areas that would have to wait many years for cables.
In the wired world, boundaries between networks are quite clearly defined: Whoever owns the cables or the devices connected to them controls the network. There are generally two types:
- Wide Area Networks (WANs) cover a long distance, from several kilometers to the entire world or beyond. They are usually run by telecom companies and carry voice or data for various customers. The Internet and the phone system are both comprised of many WANs. They are often called public networks, because they carry traffic for anyone who can pay. (In this case, public does not refer to ownership: Whether owned by a government, a traded corporation, or a private individual, a network that carries traffic for others is considered public.) WANs are sometimes divided into subgroups, of which, the most important is the MAN (Metropolitan Area Network), a type that covers a city or other region of only a few kilometers. Because radio waves have a limited range, most wireless WANs are MANs. The exceptions are satellite networks, which can cover intercontinental distances.
- Local Area Networks (LANs) cover only a short distance, usually 100 m or less. They are usually installed within homes or offices and are accessible only to the residents or employees. For this reason, they are referred to as private networks. The PAN (Personal Area Network) is a special case of a wireless LAN, with a particularly short range. It can cover a distance of only 10 m and is envisaged as a way to connect devices carried by a single individual.
Page 1 of 5