As a stand-alone device, the Pocket PC can be a great personal and business tool. But its real power is displayed when it's connected to the outside world. As a connected device, it becomes not only a source of timely information for the Pocket PC user, but a means of sharing important information with friends and associates. Of course, all Windows Mobile devices come with the ability to connect to a desktop PC via a sync cable. But a cabled solution interferes with the mobility of the device. It's the combination of a Pocket PC and a wireless data connection that delivers the greatest functionality.
The number of wireless options available to Pocket PC users has increased, further complicating the already confusing subject of wireless connectivity. The goal of this article is to unravel this confusion.
A few words about data transfer rates
When comparing the speed of various wireless technologies I will be using "bits per second" or "bps" as a measure of data transfer rates. This is a measure of the raw speed at which the wireless interface communicates. A single bit is the smallest possible piece of information. A single character of text is typically encoded into 8 bits. In addition, there is an overhead associated with any type of data communications that typically eats up another 2 bits per character. You can approximate the number of actual characters that can be transferred per second by dividing the bit rate of a particular connection by 10.
Other factors influence the data transfer rate. Because all wireless technologies are subject to errors, all include some type of error checking procedure. If the wireless connection is poor, errors will result and some data will need to be re-transmitted, slowing down the data transfer rate. Also, many wireless technologies are asymmetrical, which means that the transfer rate in one direction is faster than in the other. Finally, many wireless networks use data compression techniques to speed up the overall throughput. More on this later in the article; let's look at some specific wireless technologies available for the Pocket PC.
Infrared communications
All Pocket PCs and Smartphones include short-range wireless capability via their built-in IrDA port. This port produces a rather weak beam of infrared light to transmit data from one Windows Mobile device to another. Because a beam of light is used, the IrDA ports on the two devices must have a direct line of sight to each other. And because the beam is weak, the devices must be rather close together. Formal specifications say they have a range of just under 2 meters (6 feet), but in practice the reliability of the connection tends to drop off substantially at distances of more than 1 foot.
On the Pocket PC, the data transfer rate of IrDA is limited to a maximum of 115 Kbps, which is the same speed as a standard cabled serial port. You may notice that many laptops offer "FIR" (Fast InfraRed), which supports speeds of 4 Mbps. While the Pocket PC doesn't offer such speeds, FIR is backwards-compatible with standard IrDA. That means that Pocket PCs can communicate, albeit at the lower speed, with FIR-equipped laptops.
All versions of the Pocket PC have the ability to "beam" data to other Windows Mobile devices via the IrDA port. In addition, Pocket PCs introduced during and after 2002 have the ability to swap Calendar and Contact information with Palm OS PDAs using IrDA (Fig. 1). Some portable printers have IrDA ports what will accept data from Pocket PCs as well with the appropriate software installed.
Fig.1: The Pocket PC's IrDA port lets you send and receive contacts, calendar appointments, files, and more to and from another Pocket PC or Palm OS device.
A few Pocket PCs come with commercial-grade infrared ports, which have a greater range. With the appropriate software, this allows them to be used as a remote control for TVs, VCRs, DVD players, etc. HP's iPAQ hx4705 is one such device. It comes with Nevo's Universal Remote Control software built in (Fig. 2).
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