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Maturing Technologies: Wireless and Mobile Systems

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For this article on mobile computing, I take the technology to task. I look at wireless and mobile computing technology from two perspectives: that of a producer (someone who wants to make money from his efforts) and that of a consumer (someone who may hate computers but is willing to pay for the privilege).

Coming to Terms with Terms

Mobile computing technologies generally break down into either long-range communication systems or short-range communication systems:

Short-Range Mobile Computing Technologies

  • Wireless Ethernet—Also called "Wi-Fi" or "802.11 wireless," this is a well-known radio Ethernet connection system that you may have installed in your home for access to the Internet. Most laptops sold today have a Wi-Fi antenna already installed. A Wi-Fi network may range up to hundreds of feet.
  • Bluetooth—This is a private wireless connection method for specific devices. Bluetooth is the accepted protocol for connecting devices like wireless phone headsets to their base stations. Bluetooth has a range of about 1 meter (class 3), 10 meters (class 2), or 100 meters (class 1). This protocol uses a clever mechanism to avoid conflicts with other Bluetooth devices nearby. Bluetooth devices shift through 79 frequency channels at a rate of about 1600 shifts per second. In this way, when two disparate devices encounter a frequency conflict, they do so for only 1/1600th of a second.
  • IrDA—Short for "Infrared Data Association," IrDA is a very short-range communication specification that uses infrared light pulses as the signal carrier. This is the same technology that your TV remote control uses. A typical application of IrDA is to connect a PDA or PocketPC to a full-sized PC for data synchronization. IrDA communication is best somewhere between 5 cm and 60 cm and must be on a direct line of sight.

Long-Range Mobile Computing

  • GSM—Global System for Mobile Communication is the standard for cellular communication worldwide. About 2 billion people in 210 countries use this specification. GSM is a second-generation technology that was designed to accommodate digital phone communication, data, and even video.
  • GPRS—General Packet Radio Service is an enhancement to GSM that allows packets of digital data to be sent over a cell phone network. This technology allows you to display an Internet Web page on your cell phone and is also used for text messaging. GPRS is slow, about the same data delivery rate as a household dial-up line.
  • GPS—The Global Positioning System is a worldwide technology in which signals received from special satellites are interpreted by a device to determine a fairly exact position on the earth's surface.

A Producer's Perspective

As a producer of a mobile computing service, you must evaluate the various technologies available—their strengths and limitations—and build your application accordingly. Currently, no one solution approach works for all situations, and no single device affords all the capabilities that may be required. A PDA, PocketPC, or Smartphone can do many things, but it's still small and has a limited display capacity.

Chances are, a combination of COTS (commercial off-the-shelf) components will be brought together to build a solution. For example, you may have a desktop PC in the office that uses a standard Web application to maintain a database on a Web server. The PocketPC/Smartphone devices in the field run applications that access that database through a Web service running over the cell phone system. From just about anywhere, an order can be placed, confirmation received, and inventory relieved in near real time. The PocketPC/Smartphone applications may even take advantage of the device's built-in GPS to assist with routing, facilitate transactions, and provide tracking.

A Consumer's Perspective: Mobile Computing on the Road

To examine mobile computing from a consumer's perspective, we take to the open road. Tomorrow morning my nine-year-old son and I leave for a two-week car trip up and down the West Coast. We will exercise various aspects of the technologies that make up the term "mobile computing" and see what is and what isn't possible today.

For this expedition, we're equipped with the following typical mobile computing gear:

  • An IBM laptop computer with IrDA, Wi-Fi, and a GPS with nRoute mapping software
  • An HP iPAQ PocketPC with IrDA, Bluetooth, GSM/GPRS, a digital camera, and a GPS with Pocket Streets mapping software
  • A 12-volt DC to 110-volt AC power inverter

Both the laptop and the PocketPC are running ActiveSync, Microsoft's utility for transferring data to and from your PocketPC and your laptop.

With the exception of the power inverter, these are the devices a traveling businessperson or vacationer might carry. The power inverter plugs into a 12-volt power source and produces 110-volt AC output. This piece of equipment, it turns out, is key to mobile computing because one of the restrictions to success is limited power. Laptop batteries are good for a few hours at best (you've seen people sitting close to a wall outlet in airports).

We will, through the course of the trip, attempt to conduct ordinary business computing tasks:

  • Making phone calls
  • Sending and receiving email, text messages, images, and other attachments
  • Making inquiries, securing hotel reservations, and conducting other business on the Internet
  • Using advanced mapping systems to find points of interest
  • Using GPS positioning and route optimization technologies
  • Submitting this finished article to my editor, Victoria Mack

OK, then! Let's test the state of the art out on the open road where, say, a traveling salesperson spends his or her days.

With the first day came the first problem. We needed a place to buy all of the things we forgot. By the time we realized we had forgotten things, we were in a completely unfamiliar city, so the first task was to ask our GPS mapping software how to find one of those "have everything" stores. We typed "Target" into the nRoute application and promptly received accurate turn-by-turn voice instructions guiding us through the city like natives.

Next, we needed to check email. Since our PocketPC is also a cell phone, the GSM network is available for transferring email (note that in Oregon, where we live, "Blackberry" is something you make jam out of). With the GSM network comes GPRS, the packet-forwarding service built on top of GSM. The cell phone infrastructure has become so complete that the only place we were not able to receive GPRS service was in the national parks (and rightfully so). Note that the downside of GPRS is the cost. You can either pay by the packet for your data transactions, or you can pay a hefty fee (about $40 a month) for unlimited data.

GPRS is also capable of supporting ordinary Internet activities like using Google to conduct research or reserving a rental car online. The only restriction is the device you're connecting with must be GSM-enabled (e.g., a cell phone). You can't use your wide-screen laptop, only the tiny screen on your PocketPC or PDA, so some pages can be rendered useless.

Every hotel we stayed in had Wi-Fi service available with one exception. Ironically, the one place we had trouble was in the center of Los Angeles, where we finally got a weak but usable signal from an unsecured hot zone provider named SidsGottaRock11. Thank you, Sid11, for your hospitality. In some cities (the smaller, the better, it seemed), we had a choice of three to five networks to choose from, the extras leaking in from adjacent hotels.

A problem you may have with ad hoc Wi-Fi is you may not be able to access your email through the hotel's network, so you may have to establish a quick dial-up session from your room directly to your ISP.


Wireless and mobile computing can be considered a viable solution option but, at the time of this writing, you still can't bet the entire farm on it. We're getting closer, but there are still holes in the system. You have to have another plan. For example, if your business is fairly static, like a patch of sales contacts that change infrequently, you could design your system so that it can operate autonomously, at least for a limited period of time. Correspondingly, your system should allow for problems in synchronization and deal with the consequences.

Making your business platforms mobile adds yet another layer of complexity and dependency. Further, the very acts of working with mobile systems may prove more time-consuming than you might think. For example, one secured Wi-Fi system I accessed was intended for Apple computer users (AirPort.) To access this network with a Windows PC, I had to conduct some research on the Internet to learn how to convert the network key. Nevertheless, the infrastructure for wireless and mobile computing is there, and more and more solutions will be developed to take advantage of it.

Through the convergence process where disparate technologies come together in a single package, more and more solution options will be available. In the years to come, we'll all be carrying a PocketPC or a Smartphone, with wireless Internet access, a GPS, Bluetooth, and IrDA. Oh, yeah, and it's also a phone.

Chris Peters has 27 years of experience in the IBM midrange and PC platforms. Chris is president of Evergreen Interactive Systems, a software development firm and creators of the iSeries Report Downloader. Chris is the author of The i5/OS and Microsoft Office Integration Handbook, The AS/400 TCP/IP Handbook, AS/400 Client/Server Programming with Visual Basic, and Peer Networking on the AS/400 (MC Press). He is also a nationally recognized seminar instructor and lecturer at Eastern Washington University. Chris can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

Chris Peters has 32 years of experience with IBM midrange and PC platforms. Chris is president of Evergreen Interactive Systems, a software development firm and creators of the iSeries Report Downloader. Chris is the author of i5/OS and Microsoft Office Integration Handbook, AS/400 TCP/IP Handbook, AS/400 Client/Server Programming with Visual Basic, and Peer Networking on the AS/400. He is also a nationally recognized seminar instructor and a lecturer in the Computer Science department at Eastern Washington University. Chris can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..

MC Press books written by Chris Peters available now on the MC Press Bookstore.

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