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Mobile CoDe.NET: Microsoft Mobility 101 : Page 6

Does Microsoft have a real development solution for handheld devices or will other vendors continue to grab the spotlight? Here in the first installment of Mobile CoDe.NET, we'll describe the OS choices and software development tools and we'll lay out the yellow brick road that you can follow to start building your own mobile solutions.


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The Role of Wireless in Mobility
Wireless connectivity may not be essential to mobile applications since offline modes with delayed synchronization offer a viable alternative. But truly agile mobility scenarios involve immediacy, which requires real-time access to server-side resources. More options become available and true automation is achieved only with a reliable wireless access to your enterprise resources. There are many types of wireless networks and I want to bring you up to speed with the basics. The most well-known type of wireless access is Wireless Local Area Network (WLAN), which you'll find in corporate scenarios. With low deployment costs and easy roaming capabilities, Wi-Fi—as it is known—easily connects internal users, meeting rooms, common work areas, warehouses, large surfaces and many other types of deployments, including college buildings, hospitals, and more. Wi-Fi allows you to build your own wireless network with wireless hubs—or access points that can reach out to hundreds of feet in radius. The most common specification is 802.11b, found in most offices and wireless home networks today, which supports transfer rates of 1-11 Mbps 802.11a is also available and supports up to 55 Mbps. but is incompatible with 802.11b hardware. The upcoming 802.11g will support transfer rates up to 55 Mbps. and will be compatible with both the "b" and "a" specs, but since the "g" hardware available today is based on a draft specification, I would steer clear of "g" hardware until the spec is final if I were you. Security is of course of big concerns for many people when wireless enters the room and many reliable options are available today. I'll cover more on this topic in upcoming issues.

Another well-know but little-used technology is Bluetooth, which enables you to set-up a Personal Area Network (PAN). Bluetooth allows your personal devices, such as PDAs, phones, portable printers, and notebooks, to talk to each other over wireless. With a limited range of roughly 30 feet, this is the type of network you carry around with you. For example, with a Bluetooth-enabled Internet phone, a Pocket PC device with Bluetooth (such as an iPaq) can "borrow" the Internet connectivity from the phone, thus using it as a wireless modem to check e-mail and surf the mobile Web. Nationwide wireless networking is the dream, and we are getting there. Some telecom companies have started to deploy Wi-Fi "hotspots" in high-traffic areas—like T-Mobile in Starbucks Coffee houses, but such an approach leaves many gaps. True on-the-road access requires a Wireless Wide Area Network (WWAN). Telecom carriers like AT&T Wireless and Sprint provide such networks and allow you to connect to the wireless Internet using a standard data plan as you would with a mobile phone and a voice plan. Contrary to voice plans though, data access is billed based on bytes transferred, not the time you are connected. You can typically get a per-Megabyte package or subscribe to an unlimited access for less than $100 per month in some areas in the US. Canadian subscribers can typically get an unlimited package for approximately $50 CAD per month with Rogers AT&T Wireless.

The CLR in the .NET Compact Framework shares many commonalities with the full version.
There is a tug-of-war between two camps when it comes to WWAN technologies. On one side we have GPRS, or General Radio Packet Services, from carriers relying on GSM networks for voice. On the other, CDMA networks use 1xRTT (Radio Transmission technology, also known as CDMA2000)—or 1X for short—for wireless data access. Since GPRS is widely used in Europe where wireless has at least a two year head start on the US, it is a more mature technology than 1X and many more GPRS devices are available than there are 1X. On the other hand, 1X is faster than GPRS with theoretical connection speeds of up to 144 Kbps compared to the usual 112 kbps on GPRS. GPRS can reach up to 171 Kbps at its highest level in the spec, but this is rarely supported in the hardware. In reality, benchmarked speeds for both oscillate just below a 56.6 Kbps modem, with a slight advantage in the 1X camp depending on which carriers are compared. There is more to these specs than their connection speeds but it is beyond the scope of this column to dig deeper in WWAN analyses. Both specs will eventually merge sometime in the future with UMTS (Universal Mobile Telephone Service), also known as WCDMA (Wide-CDMA) or its popular name: 3G. This next generation of WWAN networks will support transfer speeds of 2 Mbps and higher on a national scale, but don't expect them for quite a few years yet. Both 1X and GPRS already have a migration path to 3G, such as GPRS/EDGE which means the transition shouldn't be too painful. Don't expect too much forward-compatibility on the part of your devices though.


But enough about hardware and networks, let's get back to the world of software.



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