Not too long ago, the term "business-class wireless networking" was an oxymoron. After all, how could a wireless network be business class when it failed to match wired networks in terms of speed, reliability, and cost?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Today's wireless networks can be considered business class in every sense of the term. An emerging generation of sophisticated technologies and standards is inspiring a growing number of businesses to roll up their cables and head to the airwaves. "In the years ahead, nobody is going to trip over a cable anymore," predicts Roger Entner, wireless networking program manager at Yankee Group, a technology research firm.

Wireless networking is a natural outgrowth of the business communications revolution that began with the mobile phone, says Warren Wilson, wireless practice director at Summit Strategies, a technology-market research firm. "The idea that you can talk to anybody from anywhere has opened people's eyes to the utility of wireless, and now we're seeing great growth in data services to complement that."

How Wireless Networking Works

Every wireless network relies on two basic components: a transmitter and a receiver. The transmitter, which is wired to or built into a computer, PDA, or other device, acquires data from that device and radiates the information across an area. The size of the area depends on the transmitter's power, the frequency it's tuned to, and any obstacles that get in the way. The receiver, which is also wired to or built into its corresponding device, picks up the signal radiated by the transmitter, decodes it, and then sends it to the computer, PDA, or whatever device it's connected to. In practice, most wireless network-connected devices are equipped with transceivers, which are combination transmitter/receivers that allow two-way duplex communication links.

Why Go Wireless?

There are many reasons why a company may decide to choose a wireless network technology over a wired system. A leading motivation is cost. Wireless systems spare companies the expense of installing costly copper or fiber-optic cables. This is a particularly important consideration for businesses that work inside old or historic structures, where drilling through walls and ripping up floors may be either impractical or unacceptable.

The cost disparity between wireless and wired grows with the network's size. Running cables between buildings or leasing cable capacity for communicating with users scattered around the world can be much more expensive than establishing wireless links. Additionally, wireless frees organizations from the expense of replacing damaged or broken cables.

Wireless networks tend to be more convenient than their wired counterparts. It may take several days or weeks to lay the cable required for a wired network. A wireless system, on the other hand, can usually be brought to life within a few hours—sometimes within minutes. This is an important feature for organizations that need to create networks for use at trade shows, disaster sites, and other temporary locations.

Easy scalability is another reason a growing number of organizations are turning to wireless networks. Expanding a wired network typically requires running new cables to the devices that need to be brought into the system. Access to a wireless network, however, usually requires little more than attaching a wireless network interface unit to the new devices.

Finally, for many companies, employee mobility is a key reason for adopting a wireless network. Just as mobile phones have freed users from wire-line telephone networks, wireless networks bring anytime, anywhere data access to laptop computers, PDAs, and other mobile devices. This is particularly useful for organizations with onsite or offsite mobile workers, such as factories, shipping companies, and public utilities. "The idea is that you can increase productivity, which, hopefully, leads to increased revenues and potentially decreased costs," says Phillip Redman, mobile wireless networks research director for Gartner, a technology research company.

Wireless Local Area Networks

Wireless local area networks (WLANs) are designed to interconnect computers (including laptops and PDAs) and peripheral devices (such as printers and modems) located inside offices, buildings, or small campuses. A WLAN functions just like a wired LAN, allowing users to share files, run programs, receive e-mail, access printers, and perform other common tasks. In fact, it's quite possible to use a wireless LAN and not even be aware of the fact. The WLAN market will grow fivefold over the next three years to over $5 billion, forecasts Summit Strategies.

The first truly successful wireless networks were systems that met the performance and compatibility standard set by the Institute of Electrical and Electronics Engineers (IEEE; www.ieee.org), a professional membership and standards-setting organization. The first products based on the IEEE 802.11b standard were released in late 1999 and early 2000 by vendors including 3Com, Cisco Systems, Intel, and Nokia. The IEEE 802.11b standard calls for throughput at 11 Mbps, which is about the same rate as wired 10BaseT Ethernet LANs. The technology operates in the 2.4-GHz radio frequency band.

IEEE 802.11b products are often referred to as Wi-Fi or 802.11b devices. Wi-Fi is short for "wireless fidelity," a term coined by the Wireless Ethernet Compatibility Alliance (WECA; www.wirelessethernet.org). Products certified as Wi-Fi by WECA are interoperable with each other even if they are made by different manufacturers. A user with a Wi-Fi-certified product can use any brand of access point with any other brand of client hardware that is built to the Wi-Fi standard. Products must be tested and certified by WECA before they can be labeled Wi-Fi.

Although IEEE 802.11b brought WLANs out of the technology wilderness, new standards are arriving to provide even better, more reliable performance. The recently ratified IEEE 802.11a, for example, operates at speeds of up to 54 Mbps, allowing WLANs to accommodate heavier, multimedia-rich traffic loads. The standard should go a long way toward relieving interference problems reported by many IEEE 802.11b users, because it uses the less congested 5-GHz band allocation as well as an improved frequency division multiplexing (FDM) transmission technology. (FDM transmits multiple signals simultaneously over a single transmission path.) The first 802.11a-compatible products are just now coming to market.

Another WLAN standard, IEEE 802.11g, is waiting in the wings. This specification provides a maximum 54-Mbps throughput, but operates in the 2.4-GHz band. Since the technology operates on the same frequencies as IEEE 802.11b WLANs, it's designed to provide a simpler and cheaper upgrade path than 802.11a. Volume shipments of 802.11g products are set to get underway in the second half of this year.

Also on the drawing board is IEEE 802.11e, a WLAN standard that will improve built-in quality-of-service support. IEEE 802.11e-compatible systems will allow network administrators to prioritize and control certain types of content flowing across a network, ensuring a dependable minimum throughput. Such a capability is crucial for WLANs that handle voice and video content, which can degrade severely in a multifunction network.

The U.S. isn't the only country designing high-speed WLAN technology. In Europe, HiperLAN/2, a non-IEEE initiative, is generating considerable interest. Backed by telecom heavyweights Ericsson and Nokia, HiperLAN/2 uses a different networking architecture than IEEE 802.11a, yet it is similar in that it tops out at 54 Mbps, uses the 5.2-GHz band, and relies on frequency division multiplexing. For wireless LAN adopters, HiperLAN/2's great strength is its strong security, including built-in encryption and authentication capabilities. HiperLAN/2 and IEEE 802.11a have so many similarities that many wireless-industry leaders are predicting that the standards may someday unify.

WLAN Components

Assembling a WLAN requires purchasing and installing several different components, such as servers, access points, wireless gateways, and network-interface devices. Several manufacturers, including 3Com, Cisco Systems, Proxim, and Symbol Technologies, provide these products in full-system packages or as separate components.

For any network larger than a pair of PCs connected ad hoc, a wireless access point is needed. The access point is a transceiver that converts airwave data into wired data, and vice versa, allowing it to act as a bridge between a wired LAN and wireless clients. An access point can support a small group of users (usually a maximum of 50 to 70) across a range of several hundred feet. A large wireless network will require several access points. "You can just go into a store, buy an access point for a couple of hundred bucks, bring it into your office, plug it into the RJ-45 jack on the LAN, and you've just wirelessly enabled your LAN," says Summit Strategies' Wilson.

Wireless network servers operate in the same way as their wired counterparts. The only difference is that instead of (or in addition to) connecting to a wired network environment, the server is linked to an access point.

Wireless adapters are the radio transceivers that link a computer or other device into a WLAN, the wired equivalent of a wired Network Interface Card (NIC) or Ethernet adapter. Adapters come in many different shapes and sizes. Models designed for PCs are available as plug-in PCI cards or external boxes that connect to a USB port. Laptop computers and PDAs often use PC Card- or even CompactFlash (CF)-sized adapters cards; there's now a trend of offering built-in wireless adapters.

Wireless gateways are devices that allow WLAN devices to share broadband Internet service through a DSL, cable, or other type of high-speed connection. With some models, the gateway also functions as a firewall, protecting network users from viruses, Trojan horses, worms, and other types of malicious codes.

WLAN software, when required, is usually supplied by the wireless network vendor. Many WLANs require nothing more than a driver, which is easily added to the computer's operating system. Additionally, software vendors, such as Reefedge and Vernier Networks, offer management products that are designed to help network administrators organize and secure a WLAN.

Wireless Personal Area Networks

Although WLANs are rapidly proving their worth in traditional office environments, the technology is rapidly branching out to link users together in a variety of other private and public settings. By connecting desktop PCs, laptops, PDAs, and Web phones to each other and public networks, Wireless Personal Area Networks (WPANs) are redefining connectivity.

In an office environment, a PAN allows devices to work together and share information and services, much like a WLAN, only across a smaller area. For example, a file called up on a mobile device could be wirelessly sent to a printer to produce a hard copy document. At a conference, electronic documents could be instantly distributed to every audience member with a compatible laptop or PDA. Over the next several years, PANs are expected to become available in many locales, such as trade show floors, hotel lobbies, airport departure lounges, commuter trains, and even aircraft passenger compartments. "We'll start to see a pickup in the next year or so, but it's still an issue of having enough locations for it to be worthwhile to the business traveler," says Amy Cravens, a voice and data communications analyst with Cahners In-Stat, a technology research firm.

One way to create a small WPAN is with an infrared (IR) link. IR is a low-cost optical technology that provides one- or two-way, high-speed digital exchanges at speeds of 9.6 to 115.2 Kbps. High-speed extensions, now available to device manufacturers, can bring IR's speed up to about 4 Mbps. Many laptop computers and PDAs already come with an IR interface that lets users zap commands and files to other systems and compatible peripherals.

IR distances are short—typically under four feet. Because IR systems use narrowly focused beams of light, it's difficult—but not impossible—for unauthorized parties to intercept transmissions. "It's a safe medium, since you basically have to stand between both users to intercept a transmission," says Gartner's Redman.

Given its severe distance limitation and pokey data transfer rate, many experts believe that IR is best suited for short-duration, one-to-one applications, such as PDA-to-PC syncing and onsite payment processing. The Infrared Data Organization (IrDA; www.irda.org), a trade group of companies that manufacture and purchase IR products, is currently working on a standard for proximity payments. This technology would allow people to zap payment information from a PDA or mobile phone to a cash register, vending machine, or other point-of-payment device, eliminating the need to fumble with credit cards or cash.

A longer-range and faster PAN technology is the highly touted Bluetooth. Named after a medieval Danish king, Bluetooth supports wireless communication between laptops, PDAs, Web phones, and an endless array of other gadgets. The technology's promise is absolute: no cables to trip over, no plugs to jam or break, and data transfers at speeds up to 1 Mbps over a 30-foot range.

Bluetooth technology is based on the proposition that while it's becoming increasingly easy to fling information from one side of the world to the other, moving data just a few feet is a far more troublesome matter. Ericsson, IBM, Intel, Nokia, and Toshiba formed the Bluetooth Special Interest Group (SIG; www.bluetooth.com), the specification's guiding body, in 1994. After a slow start, membership has grown quickly. The organization's ranks now include just about every major computer and telecommunications company, plus a growing array of startup companies.

Bluetooth, which is based on 802.11 technology, introduces the concept of plonk and play. (Users plonk two Bluetooth devices down near each other and they interact.) Bluetooth uses spread spectrum technology that hops signals from one frequency to another at set intervals. The advantage to this approach is the generation of sturdy wireless links, particularly in electrically noisy environments. The frequency hopping, along with streaming data encryption, provides a basic security umbrella. Another advantage of Bluetooth is its use of a universal frequency set, which eliminates the compatibility problem of different hardware built for different networks in different countries that has tormented mobile-phone marketers.

After several years of viewing the technology with a mixture of skepticism and apprehension based largely on a lack of understanding of the limits of its capabilities, device manufacturers are gradually warming up to Bluetooth. The technology is starting to emerge in headsets and mobile phones, as well as in adapter cards and interfaces for laptop computers, PDAs, and printers. According to Joyce Putscher, director of converging markets and technologies at Cahners In-Stat, shipments of Bluetooth-enabled products will exceed those of PCs by 2003, with over one billion Bluetooth-enabled products out in the markets by 2005.

Meanwhile, the IEEE is looking to extend the PAN concept with its proposed 802.15.3 standard. This specification, which is still in the development stage, would pave the way for the short-range wireless transmission of images and streaming multimedia. Besides PDAs and computers, IEEE 802.15.3 would support digital still and video cameras, cable TV set-top boxes, MP3 players, and a variety of other mobile and stationary devices.

Wireless Wide Area Networks

Unlike WLANs and WPANs, which are designed to cover, at most, a range of a few hundred feet, a wireless wide area network (WWAN) can cover an area ranging in size from a city to a nation. Some WWANs are even global in scope, allowing organizations to connect people and separate local networks across continents. "Wireless WAN applications are definitely providing value, but their uptake has been slowed somewhat by the economy and also by the fact that it's taken longer than many carriers had expected to roll out next-generation networks," says Summit Strategies' Wilson. "They're more complex than the carriers had imagined, and so the explosions of wireless WAN-based applications that many thought would occur by now really hasn't."

Potential WWAN adopters have several options. On the citywide level, fixed wireless systems come in two major types: local multipoint distribution service (LMDS) and multichannel multipoint distribution service (MMDS). LMDS works in the 28-GHz range in the U.S. and from 24 GHz to 40 GHz overseas. The technology offers links from one to four miles, depending on the terrain and other conditions, between buildings and campuses. LMDS provides bandwidth in the 53-Mbps to 622-Mbps range. MMDS works in the 2.2-GHz to 2.4-GHz range and offers connections of up to 30 miles. Transfer rates as high as 27 Mbps are possible; services targeted at small businesses usually weigh in at less than 1 Mbps. MMDS was designed primarily as a wireless transmission medium for pay TV before cable and direct broadcast satellite (DBS) became popular. It's now mostly used to provide high-speed wireless Internet access across metropolitan areas.

To achieve national and global coverage, businesses often turn to satellite-based wireless systems. With landline service providers continuing to focus on urban and suburban customers for T1, DSL, cable, and other broadband technologies, satellites provide an attractive alternative for the bandwidth-starved.

Although satellite data services have been available for several years, true two-way broadband performance is a recent development. Until a few months ago, next-generation IP-oriented satellite service providers offered only hybrid satellite-landline services that allowed high-speed downloading, but forced users to rely on snail's-pace 56-Kbps modems for upstream links. Now, companies such as DirecWay, StarBand, and Tachyon are providing true two-way satellite-based broadband services. Two-way satellite services use a dish that's slightly larger than the models used by satellite TV receivers. Tachyon's service ranges from 128 Kbps to 2 Mbps on the downstream and from 64 Kbps to 256 Kbps on the upstream. StarBand provides downstream speeds as fast as 500 Kbps and upstream rates of up to 150 Kbps. DirecWay offers up to 400 Kbps on the downstream and 256 Kbps upstream.

More companies are preparing to enter the broadband satellite market during 2002 and 2003. Spaceway, developed by Hughes Network Systems, Astrolink, from Lockheed Martin, and EuroSKyWay, from Italian company Alenia Spazio, plan to offer services with upstream and downstream rates of about 512 Kbps and 2 Mbps, respectively.

Despite the need to install dish hardware, many satellite customers appreciate the technology's reasonably straightforward sign-up and installation process. For organizations that are located in places where DSL, cable, or T1 connections are unavailable or unaffordable, satellite service is the only way to provide wide area connectivity.

Wireless Pitfalls

Wireless technology is designed to be easily accessible, and that may also be its biggest shortcoming. As wireless networks find homes in a growing number of businesses, security is becoming an increasingly critical concern. The situation is particularly dire with the popular IEEE 802.11b standard, which bases its security on the easily crackable Wired Equivalent Privacy (WEP) specification. "The security part of 802.11b is not as mature as the transmission part," notes Summit Strategies' Wilson.

IEEE 80211.b's lax approach to security causes many potential adopters—particularly those involved in financial or government activities—to think twice before cutting the network wires. Tapping into a wireless LAN data stream can be as easy as driving into a company's parking lot and turning on a laptop computer. Although encryption will safeguard information from casual eavesdroppers, using it slows network performance—and serious snoops can intercept and decrypt the data. "Wireless signals, by their nature, don't respect property boundaries," says Summit Strategies' Wilson. "With a wireless LAN, you just don't have the simple protection of keeping your data stream contained inside a physical wire, and that's a situation that will never be changed."

The wireless networking industry is beginning to respond to WLAN's security problem. Major vendors, including 3Com and Avaya, now offer security add-ons that are designed to give 802.11b networks extra protection. These add-ons are already embedded in Cisco Systems' products. "The add-ons help, but they can slow performance," says Wilson.

Security issues are also clouding Bluetooth's potential. Financial institutions, among others, could view the technology's simple frequency hopping and streaming data-encryption technologies as insufficient protection for the communication of sensitive information, such as credit card data. While security-sensitive applications can be created with stronger data encryption, that means attaching an extra layer of software complexity and incurring higher costs.

Signal interference is another growing concern for wireless network adopters. Not only can networks sometimes interfere with each other (a problem in crowded office buildings), but the spectrum turf for IEEE 802.11b and Bluetooth, the unregulated 2.4-GHz band, is home to everything from cordless phones to wireless audio speakers to consumer TV video extenders. "Many wireless LAN users think their system works wonderfully—until someone in the next office decides to microwave their lunch," says Cahners In-Stat's Cravens. The IEEE 802.11a standard aims to remedy this problem by moving WLANs to the comparatively wide open, and less interference-prone, spaces of the 5-GHz band. Bluetooth users, however, will have to learn how to cope with interference issues.

The Bluetooth SIG denies that any interference exists. The organization states that its technology includes a number of design features that address interference, including fast frequency hopping and a robust radio with short range that also works to reduce interference to other devices. "A microwave oven in a nearby office will typically have no impact whatsoever on a Bluetooth transmission," says spokesman Gary Silcott. "You may notice some noise during a voice call only if you are standing right next to the oven."

Fixed wireless LMDS and MMDS systems have their share of headaches. While it's tough for a hacker to intercept line-of-site fixed wireless signals, the technology suffers from several serious technological problems. For broadband wireless to work, an uninterrupted line of sight must be established between the base station and customers' antennas. But heavy rains—or even dense fog—can block signals, especially higher-frequency LMDS links. "This isn't much of a problem in Phoenix, where it rarely rains. But, in Miami, which can experience daily thunderstorms at certain times of the year, it can be a problem," says Summit Strategies' Wilson.

Weather aside, establishing a clear line of sight isn't always possible. This is particularly true in congested metropolitan areas, where buildings can block signals, and in some suburbs, where trees and hills often get in the way. "It's not always possible to provide service to every customer that requests it," says Wilson. "That's one of broadband wireless' big drawbacks."

Fixed wireless' biggest headache, however, has nothing to do with hardware or the weather. Over the past several months, vendor instability has become a major concern. A number of major LMDS providers, including Advanced Radio Telecom, Winstar, and Teligent, have either left the market or gone bankrupt.

In the MMDS arena, all of the major carriers have discontinued or frozen service. Sprint PCS, once a big advocate of MMDS technology, has stopped acquiring new customers with its fixed wireless service, Sprint Broadband Direct. Meanwhile, AT&T Wireless has pulled out of the market and Worldcom has scrapped its plan to roll out nationwide service, offering the service in only 13 markets. All of these actions have had a chilling effect on potential and existing customers. "For many users, service coverage gaps are proving to be a headache," says Summit Strategies' Wilson. "Even getting service to customers within an established service area can be a challenge."

For two-way satellite service customers, the vendor situation is much more stable, although technical obstacles remain a big problem. Tall buildings or trees can make it difficult—occasionally impossible—to find a clear signal path. Latency is another drawback. Since satellites orbit at 22,300 miles, a signal needs anywhere from one-half to three-quarters of a second to complete the Earth-satellite-Earth roundtrip. That's not a big problem when swapping e-mail, transferring files, or casually surfing the Web, but this latency rules out two-way broadband applications such as telephone calls and videoconferencing. Satellite technology is also vulnerable to rain-fade, an atmospheric phenomenon that blocks signals during downpours.

The Future of Wireless Networking

As wireless networks head into the future, several challenges loom on the horizon. Perhaps most critical is a spectrum shortage that delays the deployment of promising new technologies. Like trees, land, and oil, the radio frequency spectrum is a finite resource. Manufacturers rolling out new wireless networking technologies are now butting up against the interests of existing spectrum users, including telecommunications, public safety, military, scientific, and broadcast interests. More efficient transmission techniques could make it easier for future wireless networking products to find an on-air home. But, the fact remains that manufacturers developing new wireless technologies must currently endure a lengthy and expensive frequency acquisition process that includes bidding large sums of money in government auctions in order to acquire vacant frequencies or convincing the FCC that a particular frequency's current user should relinquish or share control. "It's a big problem with no immediate resolution in sight," says Wilson.

Today's plethora of wireless networking standards also threatens to hurt development. Standards set by the IEEE and other organizations are designed to bring order to a chaotic industry and to prevent vendors from attempting to control specific market segments by chaining customers to closed, proprietary technologies. Yet, the very popularity of wireless standards is rapidly creating its own problem, as users and others struggle to cope with an ever-changing playing field. "Wireless standards has definitely become a growth field," says Yankee's Entner. "Things are beginning to become as confusing as the IRS code."

Most observers expect the current standards confusion to settle down over the next decade, as the various pieces of the wireless networking puzzle fall into place. In the short term, however, users will face an ever-growing muddle of standards, pending standards and proposed standards. "In the years ahead, there will be additional standards, many addressing niche and vertical-market needs," says Summit Strategies' Wilson.

Despite the challenges facing wireless network manufacturers and users, most observers believe that the technology will continue to grow more popular and eventually lead to pervasive, universal computing and communications. "In the years ahead, computer networks will be virtually inescapable," says Gartner's Redman. At that point, mobile devices will be able to seamlessly transition from office-based WLANs to public-place WPANs to home-based networks. WWANs and the Internet will give local wireless networks a global reach, allowing a PDA user walking down the street in London to zap e-mail to an office worker sitting at her desk in New York. "We'll have finally achieved the age-old goal of providing anytime, anywhere communications," says Wilson. "And it's coming sooner than many people might expect."

3Com Corp.

(800) 638-3266

www.3com.com

Alenia Spazio SPA

www.euroskyway.it

Avaya, Inc.

(888) 290-4613

www.avaya.com

AT&T Wireless

(888) 290-4613

www.attws.com

Cisco Systems, Inc.