I recently attended a Certified Wireless Design Professional (CWDP) course, host by Spectrotech and trained by Wi-Fi expert and CWNE #1, Devin Akin.
One of the highlights of a week of intense training was an exercise on the last day. Devin asked the class to break into teams and each team was to come up with as many ways to increase Wi-Fi airtime as possible. We would then reconvene and deliver our results one-at-a-time in round-robin fashion. If one team gave an answer, the others couldn’t give the answer and had to come up with their own, until all responses had been delivered. The team with the most answers would be declared the winner.
Well, with so many great professionals in each team, it’s no wonder that Devin managed to fill the whiteboard and then had to declare a tie.
Of course winning was not the real objective. The real aim was to get us thinking hard about this very fundamental aspect of delivering excellent Wi-Fi – increasing and preserving airtime. It was fascinating to see just how many ideas we, as a group, could come up with on this one question – 74 to be precise. The ideas ranged from the obvious to the creative to the seemingly contradictory..
Ways To Increase Wi-Fi Airtime
Following is a table of the class’s responses. I’ve complied these from my own notes and a photo of the whiteboard generously provided by classmate Scott . There is overlap between many of the ideas so I’ve grouped them as seemed appropriate for easier digestion.
|1||Optimise Design||5GHz vs. 2.4GHz||Encourage (exclusive) use of the 5GHz band||The 5GHz band has many advantages over 2.4, including more channel space and less interferers|
|2||Optimise Design||5GHz vs. 2.4GHz||Prevent cross-band roaming||Stop clients roaming between 2.4GHz and 5GHz by using different ESSIDs on each band|
|3||Optimise Design||5GHz vs. 2.4GHz||Selectively disable 2.4GHz radios||After optomising for 5GHz, 2.4GHz performance can be improved by disabling some radios, thereby minimising CCI|
|4||Optimise Design||Authentication||Avoid captive portals||These have a very high overhead compared to all other authentication methods|
|5||Optimise Design||Authentication||Use iPSK instead of 802.1x||While less secure, iPSK has less authentication overhead, and may be appropriate in some situations|
|6||Optimise Design||Choice of Technology||Avoid using Wi-Fi bands where there is an alterative||For exactly a wireless voice service may be better off using 1.8GHz DECT technology than contending with WLAN services|
|7||Optimise Design||Choice of Technology||Use Technology that Coexists Well With Wi-Fi||For example, Bluetooth plays nicely with Wi-Fi up to a fairly wide margin|
|8||Optimise Design||Client Behaviour||Optimise the design for client roaming behaviour||Ensure mobile clients always have options to transition seemlessly between APs. Test that they behave as expected. This will minimise probing, reassociations and retries|
|9||Optimise Design||Radio Configuration||Increase basic rate and minimum transmit rates on each ESS||Get your management and control traffic on and off the medium much quick. Block legacy clients from connecting|
|10||Optimise Design||Radio Configuration||Lower Transmit Power||In general the lowest transmit power needed to achieve the required performance should be used. This will minimise signal outside the cell|
Disclaimer: the table represents a range of views from many different Wi-Fi professionals. It is not intended as an exhaustive or authoritative list. Some of these items are actively debated among the Wi-Fi community.
You can download a full version of the table, with explanations below:
This exercise was a great way to apply some of the knowledge we’d been trying to absorb during the course of the training. And of course that’s a great way to retain information. I hope to see more of this kind of exercise in my next course!