Wireless Access

Reply
Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

AP's stop reporting client snr values

We focus on a school building scenario in which multiple AP's were deployed at the same building level. We were in the building and put two Samsung smartphones collocated to each other (both devices are associated with APs --- may or may not be the same AP). Then we checked their snr values that were pulled out of the controller.

 

Considering both devices were collocated, I am assuming that almost the same set of AP's can see both simultaneously and then report their snr values. However, we found that, for one device within a focused time window, only one AP was reporting its snr values to the controller, while for the other device at the same time window there were quite a few AP's that were reporting its snr values.  

 

Can anybody give me some hints why this could occur? Thank you.

Valued Contributor II
Posts: 804
Registered: ‎12-01-2014

Re: AP's stop reporting client snr values

Hi ,

 

Can you clarify couple of things here,

1. What is the model of those APs

2. What is the distance between those APs.

 

Please feel free for any further help on this.

Cheers,
Venu Puduchery,
[Is my post helped you ? Give Kudos :) ]
Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: AP's stop reporting client snr values

Thank you. 

 

For the first, I have no idea. I am a student researcher and I am blind to any controller/ap model, policy and performance. But I guess my school should be able to have up-to-date HW/SW, albeit probably not purchasing full-fledged features. 

 

For the second, I believe there are more 5 AP's around two examined devices. The nearest one(s) is located in the same room as devices and is only 3 meters (line-of-sight distance) away from both. There are a few that are located in neighbor rooms - the distances (line-of-sight) are around 8-15 meters.  

 

Two devices are Galaxy S5 whose snr values were greatly recorded, and Note 3 whose snr values were recorded by only one AP within the discussed time window. Before the window, however, there had been quite a few AP's that were reporting N3's snr values to the controller; and after the window, for some reasons AP's started to report N3's snr again. It seems to me that the transition from reporting to not reporting was when N3 got stationary and was stably connected, while the transition from not reporting to reporting was unclear to me. 

 

I did one more check - N3 scans AP's at every 4~6 seconds. The above can be reproduced. Interestingly enough, the "disappear" AP's albeit not reporting N3's snr replied to scans.

 

Is there any doc or whitepaper that may explain all such and relevant policies? Thank you. 

Guru Elite
Posts: 21,289
Registered: ‎03-29-2007

Re: AP's stop reporting client snr values


nzhang27 wrote:

We focus on a school building scenario in which multiple AP's were deployed at the same building level. We were in the building and put two Samsung smartphones collocated to each other (both devices are associated with APs --- may or may not be the same AP). Then we checked their snr values that were pulled out of the controller.

 

Considering both devices were collocated, I am assuming that almost the same set of AP's can see both simultaneously and then report their snr values. However, we found that, for one device within a focused time window, only one AP was reporting its snr values to the controller, while for the other device at the same time window there were quite a few AP's that were reporting its snr values.  

 

Can anybody give me some hints why this could occur? Thank you.


There are a number of reasons why this would occur.  If you do not have access to the controller, these reasons cannot be explained definitively.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: AP's stop reporting client snr values

Thank you.

Could you please give me several possible causes so that I can do more tests to guess, or any doc to explain such policies? Thank you.
Guru Elite
Posts: 21,289
Registered: ‎03-29-2007

Re: AP's stop reporting client snr values

Start with this:  https://en.wikipedia.org/wiki/Signal-to-noise_ratio

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: AP's stop reporting client snr values

Should I? Thank you, but by starting from here how long do you think I need to take to know what I really need to know? You do not have to reply if you do not know.
Guru Elite
Posts: 21,289
Registered: ‎03-29-2007

Re: AP's stop reporting client snr values

I do not have enough information to answer your question.  I need more information to narrow down the possible answers.

 

What command are you using to report the client SNR values?

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: AP's stop reporting client snr values

Hi, You mentioned there are some possible reasons. Could you name a few? I am a networking researcher - I am 200% fine with that AP's/controller is black box to me. Actually I am happy with this. If you can give me a few possible reasons/expert-level insights I can design experiments and make a guess what the root cause is.

My situation was stated in earlier posts. Let me know if it is still unclear.
Guru Elite
Posts: 21,289
Registered: ‎03-29-2007

Re: AP's stop reporting client snr values


nzhang27 wrote:
Hi, You mentioned there are some possible reasons. Could you name a few? I am a networking researcher - I am 200% fine with that AP's/controller is black box to me. Actually I am happy with this. If you can give me a few possible reasons/expert-level insights I can design experiments and make a guess what the root cause is.

My situation was stated in earlier posts. Let me know if it is still unclear.
However, we found that, for one device within a focused time window, only one AP was reporting its snr values to the controller, while for the other device at the same time window there were quite a few AP's that were reporting its snr values.

Access points scan other channels periodically (every 10 seconds) to see other clients.  If an access point has not seen a client, that could mean that it has not yet scanned its channel.  That is probably the reason.

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Search Airheads
Showing results for 
Search instead for 
Did you mean: