On 07/04/16 19:44, Kees Pronk wrote: > “you could in theory double the airtime available” > > I would be interested in your actual experience with this. Now that a > few vendors have taken this approach and others stay away from this. > > Arguments in favor of 5/5 you will find these abundant on the vendors > marketing pages, but how about : > > Extra COGS (band pass filters etc), extra complexity with your channels > plans (need a lot of separation between the 5/5 radios), you must enable > DFS channels on every AP but what about false positive radar detects? > What about the 2 radio’s ‘deafening’ each other while trying so > send/receive at the same time. > > Please keep us posted and maybe others testing with this > 1. Innovation > 2. Marketing gimmick
My vote is for 2. Marketing gimmick. Why? Because "airtime available" isn't the limiting factor for 802.11ac performance, it's "distance from AP" (well, the high SNR required to get the best rates). So I'd much rather a full-featured AP with a single 5GHz radio than one with two 5GHz or band-selectable radios. That way I can have a nice dense deployment with low powered APs and waste money on radios I'm not going to use. Lowering the AP power also increases the possibility of using 40GHz channels without interference from other APs, which again is what you need to get the most out of 11ac. Yes, there's an increased cost in cabling and switch ports, but OTOH they should run off 802.3af power, not 802.3at which would delay having to upgrade some of our older switches. In terms of our deployment, we have 1 AP per classroom, and sparser coverage in other areas. I used to see 75-80% on 5GHz, now it's a bit lower after I reduced the radio power per vendor recommendation. This is with primarily Apple devices, which are pretty good at picking 5GHz without band steering. Outside of classrooms 2.4GHz is still needed for coverage, it goes through walls in ways 5GHz can only dream of. I tried using DFS channels and 40MHz at the start of the year but I was getting a lot of radar alerts so went back to 20MHz and non-DFS in 5GHz. -- James Andrewartha Network & Projects Engineer Christ Church Grammar School Claremont, Western Australia Ph. (08) 9442 1757 Mob. 0424 160 877 ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
