Wireless options for PDAs and smartphones, Part 1
In my last article, we considered three popular wireless interfaces for PDAs and smartphones: Bluetooth, Wi-Fi and 3G. Once you've chosen the kind(s) of wireless that you want on your mobile device, you'll need to acquire that connectivity. In this article, we consider hardware options for adding wireless to your PDA or smartphone.
Embedded or add-on
Many PDAs and smartphones now ship with embedded wireless. Two built-in wireless interfaces are common in smartphones -- for example, my own Motorola Q smartphone and the popular Palm Treo 700 include Bluetooth and EV-DO interfaces. Some high-end PDAs even have three built-in wireless interfaces -- for example, the HP iPAQ hw6925 incorporates GPRS/EDGE, Bluetooth, and Wi-Fi (802.11b). Mobile devices with embedded wireless are on the rise, but there are also many adapters that can be added later using expansions slots. If you're buying a new PDA or smartphone today, which approach should you choose?
Embedded wireless has the edge for convenience, bulk, ease of use, and (sometimes) power consumption. A wireless adapter that sticks out of your PDA's expansion slot makes an inherently small device less stream-lined. Removing that adapter during travel, or when using that expansion slot for another purpose, increases the chance that you'll forget or misplace your adapter. If you buy a smartphone with built-in 3G, it will integrate seamlessly with a particular carrier's wireless service. You may even be able to ditch your old cell phone and carry one multi-function converged device instead.
But add-on adapters do have advantages -- notably flexibility and upgradeability. For example, PDAs with embedded Wi-Fi are often limited to 802.11b. If you want to upgrade to 802.11n in 2007-2008, you'll need a new wireless adapter anyway. If you buy a PDA with embedded Bluetooth 1.2, you may still want to add Bluetooth 2.0 or Wi-Fi. The same argumen
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t applies to upgrading from 2.5G to 3G data services -- although WWAN form factor options are rather limited today. In short, purchasing a PDA or smartphone with expansion slots will leave you in a good position to add or upgrade those built-in wireless interfaces later on.
What kind of add-on?
So, you've decided to add wireless by coupling an after-market wireless adapter to your PDA or smartphone. Expansion features vary widely, so considering this is extremely important before purchasing a device. Alternatives include the following:
PC cards: PC card (PCMCIA) slots are universal on laptops, but only a few PDAs can be used with PC cards. While this approach might be handy to use the same PC card in both your laptop and PDA, it's also relatively bulky and inefficient. Furthermore, you'd need PC card drivers for your PDA's operating system -- depending on your device, this can be hard to come by. PC cards that can be added to mobile devices include the Sierra Wireless AirCard 775 (GPRS/EDGE) and the ANYCOM PC-Card CF-300 (Bluetooth).
Compact Flash (CF) cards: There are two kinds of CF cards. Type I cards are about 1 5/8" square, with a smallish protrusion at the top. Type II cards are a bit thicker and bigger across the top, but still far more compact than PC cards. Today, CF slots are more common on PDAs that smartphones, and are rapidly being replaced by smaller SD slots found on many mobile devices. Nonetheless, CF cards can be added to mobile devices -- for example, the Socket Go Wi-Fi! P500 CF card (802.11b/g) and ANYCOM CompactFlash CF-300 (Bluetooth).
Secure Digital Input/Output (SDIO) cards: SD cards are widely used to add data storage to PDAs and smartphones, but the SDIO variation can also be used to add wireless connectivity. SDIO cards can be used with most new PDAs, are relatively small (24mm x 50mm), and tend to consume less power than CF cards. Mini-SD cards, increasingly common on new smartphones, are even smaller (0.8" x 0.8"). Currently, there are more SDIO than mini-SD wireless cards. A few examples include Socket SDIO Connection Kit (Bluetooth), Spectec SDIO and Mini-SD WLAN cards (802.11g), and the Palm Wi-Fi Card (802.11b).
PDA expansion slots have become more standardized over the years, but proprietary form factors can be required to augment older PDAs. For example, Sony Clie PDAs used Memory Stick Input/Output (MSIO) cards and Handspring PDAs used SpringPort expansion cards. However, any PDA or Smartphone purchased today should have at least one standard expansion slot.
Mix and match carefully
Finally, no matter which kind(s) of wireless adapters you choose to add to your PDA or smartphone, consider these additional factors:
In the end, adding wireless adapters to a PDA or smartphone isn't very difficult, and standard expansion slots are making that task even easier. However, a little up-front planning when you shop for your next PDA or smartphone can still save you heartache in the long run.
About the author: Lisa Phifer is vice president of Core Competence Inc., a consulting firm specializing in network security and management technology. Phifer has been involved in the design, implementation, and evaluation of data communications, internetworking, security, and network management products for nearly 20 years. She teaches about wireless LANs and virtual private networking at industry conferences and has written extensively about network infrastructure and security technologies for numerous publications. She is also a site expert to SearchMobileComputing.com and SearchNetworking.com.
