Electronic Design

Embedded Wireless: Too Many Choices?

So you finally got your device networked with Ethernet and it's time to go wireless. Good luck. First, you must determine whether you need cutting edge support like ZigBee, Ultra-Wideband (UWB), or run-of-the-mill 802.11g. This alone brings up a wide range of issues like required bandwidth, range, and placement of access points. One of the most important issues, though, is security.

Security and wireless should go hand in hand. Yet designers often assume built-in encryption will solve everything. The WEP (Wired Equivalent Privacy) used with 802.11b was a debacle that should have been a red flag to anyone using wireless. If you're using 802.11b and don't know about this, look it up on the Web. You should be paranoid—people really are out to get at your access point.

Fortunately, wireless encryption is getting better, and newer standards like ZigBee incorporate better encryption within the protocol. Still, encryption across the wire is just one aspect of security, and wireless support is just one link within a larger network. As more wireless devices wend their way into the home and into critical business functions, it's imperative to make it extremely difficult to compromise these wireless systems without making them impossible to use.

Security must be a part of an overall system design. It's key that each aspect of a system's wireless interface be considered. Can the device be reprogrammed? Can it be controlled remotely? Must data from the device be encrypted, or will it be adequate to digitally sign information so that a remote application knows no one has tampered with it?

There are many tradeoffs to consider, such as the amount of code, programming effort, and support necessary to provide the desired level of protection and security. Liability issues haven't really caused much of a problem for electronic products, relatively speaking. Yet isolated devices don't tend to have the same effect as connected devices, so this will probably change in the future.

So what about wireless designs in general? A wide number of options remain, depending on the chosen technology. Compact flash cards are available for most wireless technologies, like 802.11b/g. A number of development kits exist, such as the one from Ember (see "ZigBee Kit Gets Jump On Development," right), that package solutions on a module. The reference design typically is incorporated into the final product, significantly cutting down the size of the solution. Now take a closer look at the protocol stacks with an eye on security. It may save you lots of time and grief in the long run.

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