You might notice, while stopped at a traffic light, that the quality of the radio program degrades. You've experienced, this, no doubt, while listening to the radio while driving. Really anomalous (completely unexpected) results are suspect until interference is eliminated as a possibility.Īntenna orientation: Radio propagation often produces dead spots, which are actually deep fades resulting from the geometric relationship of transmitter and receiver, as well as the specific frequency being used in a particular case.
We can deal with this problem by monitoring the radio environment with a spectrum analyzer (still too expensive for most casual users), and by doing multiple (or longer) benchmark runs and averaging the results. If there's a lot of other traffic of any form, or just transient but stronger signals, the benchmark may be impacted. Because WLANs use various forms of spread-spectrum communications, we are somewhat protected, but not completely. This is because the spectrum we use is already occupied by other services and systems, and we need to put up with any radio interference that might be present - whether from other WLANs, an increasingly-likely phenomenon, or other types of devices that use the same frequency bands. The radio environment: WLANs operate in the unlicensed bands, often called the "kitchen sink" or even "garbage" bands. Here are the important ones you need to be aware of: Thus, the core principle behind benchmarking is to eliminate all variables wherever and whenever possible.Īnd therein lays the biggest problem for anyone benchmarking WLANs - the rather large number of variables.
BENCHMARK MEANING GEARS 5 SCATTERED DRIVERS
But note the variables - the driver, for example some drivers may have slower reaction times than others, and thus the potentially superior performance of a given car is masked by a variable that, when and if addressed, could yield a better result on the next run. Take two cars, have their respective drivers hit the gas at the same time and the first one to reach the finish wins. To use a simple example, consider drag racing (the legal kind, mind you). The core idea is to present two different configurations of equipment that perform the same function with an identical set of conditions and then see how each does.
While I'm not going to cover the specific results here (they'll appear in various magazines and other articles), I would like to present you with a little background on some of the core issues, subtle and otherwise, surrounding the benchmarking of WLANs in the event you ever need (or just want) to spend hours or even days on this often-revealing task.įirst of all, benchmarking has been around for a long time. I was (and, for that matter, remain more than ever) interested in various aspects of performance, including throughput, time-bounded (or isochronous) behavior critical to real-time services like voice and streaming video, load balancing and optimization, and ease of use. Some of the products tested were residential in nature (router/access point combinations), and some were aimed more at the enterprise (standalone fat APs and systems based on wireless switches). For the past few weeks, I've been locked in various dark rooms (OK, it's not as bad as that) performing benchmark tests on a number of wireless LAN systems.
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