The WiFi Continuum

On his blog, "The WiFi Decade," Dana Blankenhorn recently commented on how we have all become accustomed to the pervasiveness of WiFi in everyday life. He starts out by commenting that he is working in the reference room of the San Antonio public library, which provides free WiFi. He continues by noting that WiFi hotspots are becoming increasingly common in public spaces, particularly coffee shops, and that the WiFi bandwidth is free in a growing number of cases.

"Paid WiFi is going the way of the dodo," writes Blankenhorn. If true, this situation is quite different from even a few years ago when the installation of WiFi hotspots and the creation of countrywide, for-pay WiFi networks was viewed as an up and coming business model. Now, the store offering a WiFi connection is likely piggybacking on its own all-you-can-eat Internet connection, used primarily for its own business. Adding WiFi for customers is often a matter of adding one or two $40 access points, and away you go. Add in the coming of the automotive hotspot and the growing availability of hotspots on aircraft, and you quickly start to see a world where WiFi access is pervasive and ubiquitous.

What does this mean to you, the embedded designer? It means that you might, under certain circumstances, start to rely on the pervasive ability of WiFi access in a way resembling the ubiquitous availability of cellular telephony networks. Although standards such as WiMAX are exciting to contemplate, maybe WiFi is all you need. In fact, WiFi access points are becoming so ubiquitous that you often have access to two, three, six, or a dozen WiFi access points from any given location. That’s a log of free, global connectivity. It’s sort of hard to ignore, isn't it?

Blankenhorn's blog really makes you think. There is quite a bit of merit to this concept. WiFi is a well-developed standard. Designers have been extending WiFi’s use for unplanned applications for years and continue to do so. The hardware is well in hand – it is installed in tens of millions of laptops, desktop PCs, and wireless access points each year. WiFi has been wrung out, ironed out, and taken to the point where you might very well consider using it for diverse embedded applications.

You can add WiFi to your embedded design through a variety of means, from simple to complex. One of the simplest, called serial-to-WiFi by Digi International, converts a simple asynchronous serial port to a WiFi connection in the way that serial-to-Ethernet converters have connected simple embedded systems to Ethernet networks for years. If your embedded system needs to talk to just one client or server on the network, the simple approach may be the one for you.

Does your application require more complex networking capabilities? If so, you need to add WiFi as a native networking interface, which provides full socket-level access, so you can run concurrent servers and clients. However, if you take this route, your design will suddenly need to understand all of the complex ins and outs of networking – it will need a full network stack. If you choose to go this route, you can select from a range of WiFi modules that connect over serial ports, processor buses, USB, and Ethernet ports. The one you select will probably depend on the design and the available ports on your existing embedded design.