Wireless Access

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MVP

FHSS and 802.11b/g

We've found a document in the Arubaverse titled: Optimizing Aruba WLANs for Roaming Devices | Solution Guide

 

It is fairly old and written for controller based, 3.x software environments.

 

We're running iAP on 6.2.x so it may not apply well at all.

 

-

 

We have 10-15 iAP 105 in a store with 6 wireless bar-code scanning handheld devices and we have

1 or 2 Symbol 2.4GHz spread-spectrum access points and 5 stationary wireless devices (deli-scales)

 

Needless to say the frequency-hopping spread spectrum gear plays havoc with the 802.11 airspace.

 

The document recommends setting 1Mbps bandwidth contracts on the VLAN and forcing clients to b -- which seems to be the opposite of what I'd expect to work. I was leaning toward forcing g and higher speeds to get the clients off the air before the frequency hopper comes marching through.

 

Let's stick to the "how to manage the airspace" part of my questions here, I'll take up the "how to do it on iAP" part in the iAP forum.

--Matthew

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Re: FHSS and 802.11b/g

It's been two weeks and no one has chimed in, so here's my two cents...

My decision on what to do would be a matter of just how strong the FHSS source is, from the perception of the clients, compared the the APs. If the SNR of the FHSS source is REALLY strong, then it likely won't matter since it's gonna stomp on whatever you have in the air, but if your clients are low-bandwidth and don't need to push lots of traffic, lowering the rates to 1Mbps gives the clients the BEST chance of maintining a connection to the AP in the presence of the FHSS devices, as it presents the 'most connectable' rate in the face of adversity.

 

However, if you need more bandwidth, and if the FHSS source isn't continuous during contention (ie rapidly bursty during the interference periods), then the faster rates may make more sense to get the data off as fast as possible, accounting for (what will likely be) many re-transmits (at least your re-transmits would be 'faster' or occur more often, per se). 

The type and signature of the FHSS also comes in to play, as to what the best descision to make is. Ideally, you move clients off the frequencies afected, or your trim the FHSS available range. Otherwise, in many cases it is a best effort...

Jerrod Howard
Sr. Techical Marketing Engineer
MVP

Re: FHSS and 802.11b/g

Thanks for the feedback.

 

At some of our stores the FHSS radios are positioned "well" for cooexistence, and at others it's as if we menat them to ruin everything!

 

We'll probably wind up making more than one plan based on FHSS placement.

--Matthew

if I've helped, please give kudos
if I've provided a solution, please mark the solution so others can find it

Re: FHSS and 802.11b/g

HAHA I know the feeling. Good luck!

Jerrod Howard
Sr. Techical Marketing Engineer
Contributor II

Re: FHSS and 802.11b/g

Hi,

tuning "Interference immunity" isn't helpfull in this case?

 

V.D.

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