Wireless Systems Design

Misconceptions About Wireless Broadband Abound

Although Accessing The Internet Through A High-Throughput Wireless Connection Is The Wave Of The Future, Understanding The Meaning Of Broadband Is Still Today's Biggest Struggle.

From the highest office in the land to the average consumer, everyone seems interested in high-speed, wireless Internet access. Even the United States government has deemed this topic important. It is now proposing the construction of base-station towers on federal land. The government feels that this move will help promote the availability of wireless broadband. Echoing this enthusiasm, the FCC Chairman recently noted that wireless could be the "Holy Grail" for U.S. broadband policy. He went on to say that it could be the third "wire" into homes next to cable and telephone lines—that is, digital subscriber line (DSL). On the consumer side, rural users as well as small-business owners have shown renewed interest in high-speed Internet connections through a number of different broadband mechanisms.

What exactly is wireless broadband? The answer depends on whom you ask—be it Internet carriers, cellular-network providers, device manufacturers, or consumers. Not surprisingly, this confusion over the term's meaning has led to a variety of misunderstandings. But fear not: These myths will soon be clarified.

Myth #1: "Broadband" means cable or DSL.
This statement is partially true. Most Americans access the Internet through wired connections like broadband cable or telephone-line DSL. But wireless technology is playing an increasingly important part in broadband-Internet access—especially in the global market. In an annual study of Internet trends by Ipsos-Insight (www.ipsos-insight.com), the wireless Internet experienced an increase in usage of 145%. That rise represents 79 million unique users. The study was based on interviews in 13 key global markets with more than 7000 adults. It included any type of wireless-Internet device and access technologies that span both range and spectrum. Such technologies include Ultra Wideband (UWB), Wi-Fi, WiMAX, and 3G cellular networks (see table).

Because the word "broadband" is overused, everyone believes that they know what it represents. Part of the problem is that this term has been around for some time. Perhaps one of the earliest usages of the term "broadband" was in a 1964 report on Bell Systems, notes Jeff Hearon, Managing Director of Global Broadband Strategies (project-mbo.blogspot.com). This report explained how carrier systems—signal-modulation technologies—were first introduced in the Bell System in 1918. Broadband carriers began appearing in 1940.

During those early days of carrier-modulation technology, it became apparent that bandwidth could be divided into categories of narrowband, wideband, and broadband. Aside from a higher data-throughput capability, a broadband-communication medium had one other defining characteristic: It could be divided into multiple segments. This differentiator would become critical in future technologies like WiMAX.

Myth #2: Wireless broadband is the same as WiMAX.
At up to 75 Mbps, WiMAX technology will provide the highest throughput rate of other broadband connections. Yet it is still only one of several broadband technologies. For now, WiMAX is seen as the solution to many of the first-mile/last-mile issues. For example, it will allow a high-throughput Internet connection to locations that lack cable or DSL networks. It also may be used to connect Wi-Fi hot spots while providing both backhaul for cellular networks and enterprise-level connectivity for businesses (see figure). When the government and the FCC Chairman speak of wireless broadband, they are referring to a wireless-metropolitan-area-network (WMAN) technology like WiMAX. But what exactly is WiMAX?

WiMAX is derived from the IEEE 802.16 air-interface specification. That standard focuses on the efficient use of bandwidth between 10 and 66 GHz. It also defines a medium-access-control (MAC) layer for that spectrum. A technology that is built around 802.16a can be implemented in either a fixed-wireless (non-line-of-sight) or mobile fashion.

Just as Wi-Fi is a moniker for 802.11, WiMAX is the nickname for 802.16a. Wi-Fi is designed to provide broadband connectivity inside buildings. In contrast, WiMAX will transfer data around 75 Mbps over a distance of 30 miles (48 km) to thousands of users from a single base station.

The goal of the WiMAX Forum (www.wimaxforum.org) is to promote the deployment of broadband-wireless-access networks. This nonprofit corporation plans to do for 802.16 what the Wi-Fi alliance has done for 802.11 in terms of product certification, standard compliance, and marketing.

Myth #3: WiMAX will be the next Wi-Fi.
The above statement may be true in terms of the technology evolution that will complete the connection of every potential user to the broadband Internet. In general, however, WiMAX and Wi-Fi are complementary rather than competitive technologies. According to Nigel Ballard, Wireless Director for Matrix Networks (www.mtrx.com), "You need the backhaul before you can provide the Wi-Fi service locally." Backhauling to the Internet backbone provides the essential connection to the World Wide Web.

As WiMAX products emerge and become more cost efficient, they may compete with existing Internet-access mechanisms like T1/E1, the broadband cable modem, and DSL, explains George Wu, Director of Marketing for Fujitsu Microelectronics America, Inc. (www.fma.fujitsu.com). Yet Wu also notes that the main purpose of WiMAX is to extend the Internet's reach to rural areas that currently have only traditional dial-up connections.

Joe English, Director of Broadband Marketing at Intel, explains that one of the key differences between WiMAX and Wi-Fi is the way that the bandwidth is apportioned. "WiMAX is a grant-request system, whereas Wi-Fi is like Ethernet (i.e., it is all shared bandwidth on a segment)." English points out that WiMAX can be apportioned down into much smaller chunks: "So if you want to, you could provide a lot of bandwidth to someone like an enterprise (e.g., a 20-Mb connection)." Similarly, you could backhaul a hot spot or perform some other point-to-point transmission.

This ability to do point-to-point and point-to-multipoint connections allows WiMAX to serve as a bridge to both small urban businesses and rural areas. Cable may run right next to many small-to-medium-sized businesses (SMBs). But regulatory issues may make it difficult to access that cable. In addition, digging up the streets to gain wired access may be cost-prohibitive. In contrast, companies like VeriLAN (www.verilan.com) enable an enterprise metropolitan wireless backbone with 802.16a-like technology. This company provides a non-line-of-sight (NLOS) wireless service using pre-standard, 802.16a-like gear.

Myth #4: Wireless broadband is limited to Wi-Fi for now.
For the majority of users in the U.S., this fact is a reality. Deployments of other wireless technologies for Internet access are just beginning to surface. On the cellular-network front, for example, Verizon Wireless (www.verizonwireless.com) is in the process of completing its broadband-access technology. The technology is known as Evolution Data Only or simply EV-DO. Verizon plans to phase in the EV-DO service across most of the U.S. by 2005. Bill Stone, VP of Marketing for Verizon Wireless, notes that EV-DO may complement current Wi-Fi deployments in homes, on campuses, and for businesses.

3G-like services that resemble Verizon's EV-DO will be great for on-the-go scenarios. But consumers may still find it hard to beat the higher throughput afforded by WiMAX-based Internet access. When will WiMAX technology be readily available? According to Intel's Joe English, WiMAX will roll out in three different phases. Fixed-wireless devices, which utilize an outdoor antenna, will dominate the first phase. That phase will start at the beginning of next year.

Toward the end of 2005, there will be more indoor installations. They will resemble today's Wi-Fi access points. In the 2006 timeframe, the third phase will emerge. At that point, laptop computers will come integrated with WiMAX chips and antennas. In fact, laptops will have both Wi-Fi and WiMAX radios.

While global users may access the Internet in many different ways, the growth of wireless-broadband Internet access seems assured. For a listing of all of the contributions from which this article is derived, please visit Wireless Systems Design's forum page at www.planetee.com/Forums.

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