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The Right Amount of Power
We've all heard, "Turn the power down, shrink the cell size, and you'll get more aggregate capacity in your Wi-Fi network." It's an incomplete and bogus statement. I know, you're thinking, "OK, Mr. Smarty Pants, where are you going with this...?" First, consider that Cisco's VoWLAN 4.1 Design Guide, Page 3-3, starting with the section entitled, "Co-channel Interference Considerations" starts on a 15-page commentary that spells out in great detail something that it sums up in the beginning by saying, "The reality is somewhat more complicated because the AP influences the WLAN RF environment around it for a much greater distance than just the bit-rate boundary." I give Cisco big kudos for the clarity of explanation and visual representation given of co-channel interference in these 15 pages.
Let's restate the problem for clarity:
Regardless of how much power you're using at the AP or client, transmissions will affect the RF environment around the device at a much greater range than the data transmission actually needs to go.
Cisco makes another statement within those same 15 pages that I very much agree with, "It is not an effective strategy to reduce the overlap in order to reduce co-channel interference. As users satisfaction can be greatly affected by poor roaming performance. In contrast, call capacity can be addressed in planning and design."
What they're saying here is that you can't spread the APs out far enough to mitigate this RF interference problem because you'll break roaming, which is true for most systems. So what is this blog post all about? It's about something totally different that needed this information as a pre-requisite. :)
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