Different wireless technologies come in different devices and do different things. But no other device displays more wireless variety then a PDA.

In order of effective range (least to greatest), the four wireless technologies used in PDAs are infrared, Bluetooth, 802.11b, and 2.5G (seen in PDA/phone combination devices). Each type has its best uses, and the technologies are not exclusive.

Infrared

The first and possibly most basic wireless technology built into PDAs is IR, or infrared technology. When you think IR, think of a remote control. IR has a short range, about 10 feet—think couch to TV—and it must have a line-of-sight connection. Ever since PDAs came equipped with IR, the most common use of the technology has been to synchronize data (at 4 Mbps) with your PC or notebook. You could also beam business cards and small amounts of data between PDAs, but this never really caught on.

Some PDAs, such as the high-end HP iPAQ h5550, incorporate the stronger "consumer" IR, which can send signals from 25 to 30 feet and is typically used in remote controls.

Bluetooth

Bluetooth is similar to IR in that it has a short wireless range, up to about 30 feet; however, connecting with another Bluetooth device doesn't require a direct line-of-sight connection, as does IR. You can find Bluetooth in some PDAs, cell phones, printers, and notebooks, to name a few—and you can share data among all of them. Bluetooth has a one-way data rate of 720 Kbps.

Bluetooth-enabled cell phones are still few and far between, but using one to connect a Bluetooth-enabled PDA to the Internet is a great way to tie the two form factors together. (PDAs and cell phones have already taken one step further in convergence with all-in-one devices, though they are still too bulky to be a comfortable cell phone and too small to display a useful PDA screen.)

Bluetooth products splashed on the scene in 2000, promising to get rid of the cable tangle taking over offices. It didn't take off as people had hoped, and the rapid arrival of 802.11 technology somewhat muted Bluetooth's moment of wireless glory. But that's not to say Bluetooth is dead: It has finally found a niche, thanks to PDAs, and is enjoying an uptick in growth.

802.11b

Thanks to the current 802.11 technology rage, wireless networks are popping up everywhere—in offices, homes, and in many public hot spots (check out your corner café). Therefore, the usefulness of equipping a PDA with 802.11 capability has increased. You can browse PDA-friendly Web sites while you're out and about to check movie times, for example, or to find a street address. Although only a few PDAs have integrated 802.11, most can easily be equipped with add-ons (usually via CompactFlash adapters, with SD adapters coming soon).

Today the adapters integrated into PDAs use 11-Mbps 802.11b technology. It's likely that PDAs or PDA wireless adapters will soon have combinations of 54-Mbps 802.11a, 54-Mbps 802.11g, and 802.11b standards.

Digital Cell-Phone Technology

The use of a digital cell-phone network for high-speed transfers of video, audio, and Web downloads, as well as e-mail and text, is now in its second year. But the promised potential of full 3G capability is still several years away. 3G, which stands for third-generation cellular technology, will allow cell phones to provide a wireless connection of at least 2 Mbps from a fixed location (meaning that you're standing nearly still or moving at less than 10 kilometers per hour). The current 2.5G connections (GSM/GPRS and CDMA/1xRTT) average from 40 to 72 Kbps. Still, this is comparable to or better than a conventional 56K dial-up modem, sans wires. Although only fractionally as fast as 802.11b, 2.5G works fine for communications, e-mail, instant messaging, and limited Web browsing.

Since the amount of data being moved to and from PDAs is generally small relative to the data downloaded and uploaded from conventional PCs, the actual speed can be impressive. Add to that the fact that digital phone connections cover a much wider range than any other wireless technology today—out to the suburbs and back—and 2.5G becomes very appealing. The downside, however, is its premium pricing: Although unlimited access plans are dropping in price, they still appeal mostly to business users.

What's Best for You

Unfortunately, although there's a great argument for a PDA with built-in infrared, Bluetooth, 802.11, and 2.5G, you can't buy one today. In the meantime, just remember that infrared and Bluetooth are best for short-range data transfer. 802.11b is best if you want to do basic Web browsing with your PDA and often find yourself near hot spots (in metropolitan areas, airports, and hotels). 802.11b has a faster data rate and costs less than 2.5G. But if you want more flexibility in the way you use your PDA—if you travel in the countryside or even in cities without ubiquitous hot spots—then you'll want 2.5G and, eventually, 3G.

Copyright © 2004 Ziff Davis Media Inc. All Rights Reserved. Originally appearing in PC Magazine.