A Survey of Wireless Options for Palm Developers, Page 2
Bluetooth, a newer wireless communications protocol that has won industry support, addresses some of the limitations of Infrared described previously. In contrast to infrared, Bluetooth is not limited to line-of-sight connections; it can communicate around and through walls. It also has a wider range than IR, communicating with other Bluetooth-enabled devices up to 30 feet away.
Bluetooth also can serve as a base platform for supporting additional higher-level protocols, such as serial communications and TCP/IP. Thus it becomes possible to perform networking over a Bluetooth connection. Because it supports higher communication speeds than IrDA, networking of larger amounts of data becomes more feasible.
Bluetooth has potential for many of the same uses as infrared, including wider-range beaming of data among PDAs, and printing to Bluetooth-enabled printers. It can also be used for "personal area networks," providing communication among multiple devices in your personal space such as cell phones and pagers. Finally, with a Bluetooth network access point in range, it can be used as a gateway to accessing network resources including e-mail and Internet content.
The main problems with Bluetooth are availability and end-user experience. Unlike infrared, there are not any Palm OS handheld devices that come with a built-in Bluetooth radio, meaning that users will need to obtain a Bluetooth adapter from either Palm or a third party. Although prices are coming down for these adapters, they are still expensive enough to make one pause.
The end user experience is also less than seamless in today's Palm OS implementation. Because Bluetooth ports don't "point" at one another, Bluetooth must go through a bootstrap process of "discovering" other Bluetooth devices in the 30-foot range it is operating in. This can take a few seconds to perform, and when it is complete the users are presented with a list of Bluetooth devices to choose from.
If there is only one other Bluetooth device in range, this represents a simple tap. But in an office environment with many Bluetooth-enabled PDAs, printers, cell phones, access points, and other devices, the users must wade through screens of available devices to choose from. This can be frustrating and confusing to the end users who may already know the target device they wish to connect to.
Much excitement has arisen recently over the growth in a wireless technology known alternately as 802.11b (along with variations 802.11a and 802.11g) and Wi-Fi (a slang term commonly used in place of "802.11"). Wi-Fi is a way to wirelessly network computers over short-to-medium-range distances (up to several hundred feet, depending on an indoor or outdoor location). Like Bluetooth, Wi-Fi is non-directional, and does not require a line-of-sight to make a connection.
A Wi-Fi connection is typically made from either a PDA or a laptop to a wireless LAN access point. The access point connects to your network router/hub, and forms what can be thought of as an invisible Ethernet connection between the hub and any Wi-Fi-enabled computer in range. Speeds go up into the multi-megabyte range, making it suitable for larger amounts of data.
Wi-Fi is implemented with networking in mind, and thus is highly suited for file sharing, networked printing, office applications, e-mail, and shared Internet access. With Wi-Fi you can more or less do the same types of things you can do with a laptop and an Ethernet card. Wi-Fi access points are springing up in offices, homes, and public places like airports and coffee shops, providing laptop and PDA users with easy access to internal and public networks without requiring expensive cabling. It is even possible to "daisy-chain" access points, providing an expanded interlocking web of network coverage over a greater distance.
Because of the networking-centric nature of the Wi-Fi solution, it tends not to be viable for interpersonal communication such as beaming a contact to the person standing next to you. But as a method of connecting your computer to networks without wires, Wi-Fi is an excellent option.
As with Bluetooth, a current downside to Wi-Fi is availability. Although it is becoming common to see laptops with built-in Wi-Fi radios, Wi-Fi is still not widely available as either a built-in or even add-on adapter for Palm handhelds. Symbol has for several years made an 802.11-enabled device for its target markets, and also has produced a wonderful Compact Flash card implementation. An issue that manufacturers are wrestling with is power consumption, which can be higher than that of infrared and Bluetooth. Another is form factor, as the requirements of Wi-Fi have not matched well with the peripheral interfaces available thus far on Palm devices such as SDIO.
Despite the current lack of PDA support, it is apparent that Wi-Fi is spreading fast, and one can imagine that it will soon become rather commonplace in office environments and public places. With that kind of availability, it is hard to believe that we will not see Palm devices with built-in Wi-Fi support in the near future (in fact as a harbinger of the future, there are already PocketPC devices that are sold with Wi-Fi as an option).
Wide Area Wireless Options
This section covers some of the wireless communication options that provide PDA connectivity over very large distances, freeing the user from the need to be located in proximity to an access point or other source.
Wireless Data Networks
Over the past several years, several competing wireless data networks have sprung up, offering the equivalent of a dial-up networking account in ISP-like fashion, only without the need for a telephone jack.
A major downside to wireless data networks is coverage, which is very much dependent on location. Depending on your location, you may have excellent coverage, spotty coverage, or no coverage at all. Whether this matters will depend on how mobile you need to be. If your application will run primarily in high-density population areas and major cities, you will likely not have a problem.
If you cannot predict where your application will run, either because it will be used by people regardless of location, or because it will be used by people who are inherently traveling from place to place (here think of truck drivers or outside salespeople), the uncertainty of an available wireless connection can be a major barrier.
Coverage seems to be slowly improving, but it's easy to see that it will be a long time (if indeed ever) before wireless networks of this type will cover the entirety of the world's populated areas.
Another downside is the subscriber cost. Wireless networks incur a monthly subscriber account and a monthly charge, typically priced according to how much data is transmitted. Depending on how much data needs to be transmitted this cost can become significant, especially if you are equipping a number of PDAs with your application.
There is also the cost of a wireless PDA modem to consider. There is a wealth of modems to choose from, and that has driven down costs. Some providers even offer deals on modems if you subscribe to their wireless service. It's worthwhile to check around before buying.
Palm made a bold move several years ago by producing the first Palm OS-based handheld with a built-in wireless modem. The Palm VII, together with its successors the VIIx and i705, represent a good value for users who require fast and relatively inexpensive access to e-mail and Internet services. Palm's Palm.net service is reliable, and when combined with Palm's proprietary WCA, or Web Clipping Architecture, can deliver Internet data to the palm of your hand quickly and reliably. Palm's device is also easy to connect with, it is said to be "always on". Thus there is no need to constantly connect and disconnect, which is very inconvenient if you've ever needed to connect in a hurry.
A final aspect of wireless data networks to consider is the communications speed. Although much has been made of the impending rollout of high-speed wireless data networks, the harsh reality is that today's network speed ranges from poor to abysmal. If you are lucky enough to be in a location with good coverage, you will still suffer speeds approximately an eighth of the typical landline dialup connection. For tiny bursts of data, or very carefully architected software, this can be sufficient. It does not however make for a pleasant experience downloading e-mail or surfing the Web.