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wolfeyes
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NV2 PtMP Data Rates

Wed Jul 13, 2011 12:28 am

Hi All,

We've set a PtMP implementation with a centralized AP (433UAH) and 9 SXT clients connected on APs sector antenna.

Antenna is dual polarized (HV). Below you may find a screenshot with distances and respective SNR values.

The majority of the SXTs are located at 15km distance from sector antenna.

Each individual SXT at 15km distance gains 20mbps using bandwith test tool.

However the problem is when simultaneous traffic come from parallel SXT sessions, AP wireless interface (wlan2) cannot serve more than 10-12 mbps in total.... :( Very, very dissapointing....

Protocol used is NV2 and N-only mode (superchannel enabled) with latest ros v5.5 on ap and sxt clients. AP wlan2 hw is R52Hn.
No other 5Ghz networks exist on the area for potential interferance issues.

Is this something normal???

Which is the expected data rate thoughput on such implementations?

What we also noticed is that clients with weaker signal get very frequent disconnections whenever total data thoughput is high i.e. running bandwith test tool (control frame timeout log indication).

Please for your help and comments.
Thanks.
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InoX
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Re: NV2 PtMP Data Rates

Wed Jul 13, 2011 3:02 am

Your signals are extremely low. You should not exceed -75. This is the reason of your problem.
 
lazerusrm
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Re: NV2 PtMP Data Rates

Wed Jul 13, 2011 8:20 am

Someone needs to learn what signal levels stand for, and also what connection speeds represent.

You have major issues on your network. you're lucky you are getting as much speed as you are.

Every poorly connected client slows your entire access point down. if you want better speeds, the answer is simple:

You must increase signal strength overall.

All your clients need a minimum of -75db to achieve decent overall speeds. Also, you need to address the client that has -86 db, that unit alone will kill your

bandwidth.

-Brad
 
wolfeyes
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Re: NV2 PtMP Data Rates

Wed Jul 13, 2011 11:11 am

Thanks for your input and comments guys.

Next step is to find a closer position to shorten distance between AP and the SXTs in order to achieve better overall signals.

Sector antenna gain is 19dbi (MIMO) and SXT antenna gain is 16dbi, thus from your experience which is the optimum distance for signals -75 or better? (I mean worst case scenario for distance).
I know this is also depended on many other parameters but a rough estimation would be appreciated and not absolute distance value.

Thanks again.
 
InoX
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Re: NV2 PtMP Data Rates

Wed Jul 13, 2011 9:59 pm

If you want to keep the sxt's you may use reflectors, like I did. A 55cm offset will add 10 more dbi, exactly what you need but is some work to do.
 
wolfeyes
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Re: NV2 PtMP Data Rates

Thu Jul 14, 2011 12:32 am

I'm already using one reflector for the sxt which resides at 21km distance! :)

It does fantastic job, but as you mentioned requires extra work (and cost) to add additional reflectors for the rest of the SXTs. Actually SXT is an excellent cpe with easy installation and I'm planning to keep expanding network using this device.

Furthermore and as I had read about nv2 it is based on TDMA and one of the main characteristics is no penalty for distant clients with makes sense on PtMP environments .
What we noticed is that when the single sxt with the reflector is the only device device associated to the AP, speed test tool reaches up to 80mbps, but when all rest SXTs associated to the AP speed throughput drops at 20mbps....
So, I assume there is some kind of dependency here with the rest associated clients......

I've concluded that AP change position is one way solution for our case in order to gain overall better signals. :? .... and I'm now trying to find this new closer position... :(
However final testing will reveal the real results!
 
Ciambot
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Re: NV2 PtMP Data Rates

Thu Jul 14, 2011 2:26 am

Every poorly connected client slows your entire access point down.
@Mikrotik Staff
Can single client slow down entire AP with NV2???
 
wolfeyes
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Re: NV2 PtMP Data Rates

Fri Jul 15, 2011 4:33 pm

@Mikrotik

Can you please help us and provide some further clarifications for the previous question regarding single client behavior and AP speed for NV2 protocol?

Can a single client affect AP in terms of long distance or low signal conditions?

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