Ed Tittel's Survey of Wireless Technology
In the past five years, the wireless revolution in computing and communications has really gotten underway. Before 1998, wireless activity pretty much consisted of cell phone users, with a few forays into other uses from technology innovators such as UPS, gadget freaks, and other elements from the bleeding edge of technology. Today, wireless networking is not only becoming commonplace, it's even pretty affordable. Likewise, wireless links come in many shapes and form factors nowadays, and support a bewildering array of general- and special-purpose applications.
A quick survey of an incredibly dense and fragmented landscape tells me that exhaustive coverage of its wrinkles and boundaries is probably beyond human ken at this point. (Try using "wireless handheld" or "wireless computing" in your favorite search engine, and see how many thousands of hits come back.) Instead, let's categorize what we see, and look at some of the more well-visited parts of their terrain.
It's easy to break wireless devices and applications into several major categories, as follows:
- Wireless conventional networking. If you take away the wires that permit networks to do their thing (in most cases) and instead use wireless links between computers and devices, this is what you get. Note also that wireless networking in this context really means "wireless LANs" because mobility and reach are limited for most related technologies.
- Mobile computing applications. If you provide wireless computing for all kinds of users on the move—such as UPS truck drivers, taxi drivers, utility company workers, warehouse workers, and so forth—this is what you get. Because this application really is pretty mobile, geographic coverage can be pretty broad, but bandwidth goes down as the distances spanned increase.
- Wireless Internet access. Let's qualify this with the word "limited" because it usually occurs in the context of Internet-enabled cell phones, personal digital assistants (PDAs), or other small-screen devices. These usually have the same range and reach as cell phones (and often use cellular or related wireless telephony technology under the hood).
- Wireless appliances. These are special-purpose devices—such as global positioning systems (GPSs), vehicle monitors, map displays, and so on—that may do one-way or two-way communications to access special databases, services, and so forth.
- Wireless communications (voice and data). These come in many forms, ranging from high-bandwidth, point-to-point virtual backbones, to mid-range, relatively mobile metropolitan area technologies, to slow cellular modems that work anywhere a cell phone does.
- Wireless device docking. Creates a temporary short-range wireless link between devices (as in the infrared device links that the Infrared Device Association, or IrDA, promotes). At speeds up to 16 Mbps, it's peachy for synchronizing email, databases, and printing, among many other uses.
This survey doesn't pretend to cover the whole landscape, nor to provide lots of technical implementation specifics. Rather, we want to identify some of the main attractions in this territory, and provide a sense of what they are, what they can do, and why you might care. So, let's go take a little closer look at each of these categories and some example applications that you might find useful, if not compelling.
Wireless Conventional Networking
The greatest benefits of going wireless for conventional networking come in two primary forms. One is that it makes office layouts more flexible and does away with the need to get close to a specific wall to hook up to the network. In manufacturing situations (where work cell configurations change a lot) or on movie stages (where walls come and go regularly) this is a real hook. The other benefit is that it supports "untethered work" for those with laptops: they can carry their machines with them everywhere inside a building or on a campus and maintain a normal-speed network communication (802.11 technology runs at more or less the same speed as 10 Mbps Ethernet, discounting overhead).
Bob LeVitus, author, trainer, and Mac guru is pretty enthusiastic about this technology: "I can read email or browse the Web on my PowerBook anywhere around the house, at airports, and in a lot of hotels. It unchains me from my desk, and lets me work where and when I want to." Because such technologies provide normal network (and hence, Internet) access on conventional computers, it's a terrific boon for knowledge and clerical workers of all kinds.
It's also important to note that the limitations of conventional wireless networking included relatively limited distance ranges (usually up to 300 or 400 yards from a hub and seldom further than that). Within a hub's "service area" this technology works as advertised; outside it, nothing doing. Even so, another common weakness for 802.11 stems from many organizations' failure to use encryption for communications. This has spawned the phenomenon known as "war driving" in which hackers who cruise high-tech neighborhoods with laptops, wireless interfaces, and extra-sensitive antennas can often listen to (or log into) wireless networks all over the place.