One common question I get on unlicensed devices is what end users need to do about interference.
One common question I get on unlicensed devices is what end users need to do about interference. So far, interference is not all that big a deal. There aren't that many wireless LANs and related devices in close proximity (in the general case, anyway), and the range of said products is inherently limited. Interference from a data perspective most often shows up as short-duration point-source phenomena and may result in slightly lower throughput if it's really a problem. My 2.4-GHz WLAN was causing clicks and pops on my 2.4-GHz cordless phone. The new 5.8-GHz phone took care of that.
But what happens when the WLAN industry grows, and voice and other spectrum-intensive applications become common? Add in other 2.4-GHz traffic, and all that careful planning of access-point channel assignments and power levels is for naught. Enter the emerging field of RF spectrum management (RFSM). My first exposure to the concept, courtesy of Propagate Networks Inc., was an epiphany. Why are we investing manual labor when we can get a little software to handle this problem for us, in real-time, automatically, without our intervention?
In a nutshell, an RFSM implementation can be a planning and deployment tool, a PHY monitoring capability, a troubleshooting aid and an element in network optimization. Besides automatically configuring access points, RFSM can be used to handle security concerns, a path to fault-tolerance, a vehicle for traffic prioritization and the key to managing wireless networks that only grow over time. We could count the number of 1,000-and-over access point installations on one hand today. In a couple of years, they will be common. RFSM lets us manage the PHY in much the same way as we deal with the upper layers of the protocol stack.
However, that interference will not only come from other Wi-Fi devices, but from lots of other products as well. This means we need not just 802.11 protocol monitoring, but also a function akin to a spectrum analyzer. Cognio's Sage chip now has my attention. And let's not forget that spectrum above 5 GHz. Even though the marketing machine around .11g is undeniable, the wide-open spaces are beckoning. With the right tools, interference will not be much more of a problem in the future than it is today.
Craig J. Mathias is principal of Farpoint Group (Ashland, Mass.).