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Jafster

join:2013-02-07
111111

1 edit
reply to LLigetfa

Re: How can i use single Freq. in 4 Canopy AP's in one tower?

Click for full size
Thanks to all the comments. i am learning a lot in here.

above is my current setup and i dont have any problem with my setup. but i really want to cover the whole area using the 3 towers using 3 freq.

aeronet

join:2002-04-05
San Juan, PR

you are currently using 5 diff channels... you what to consolidate to 3? why 3 exactly? are you having issues with your PTP links?

Tower 1 and 3 appear to have 3 APs only?


Jafster

join:2013-02-07
111111

1 edit

Actually i am using currently 4 channel but we are actually i am allowed to use 3 freq only for my Canopy PMP .

i dont have any problem with my PTP. i have a separate Freq. for that.


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

1 edit
reply to Jafster

said by Jafster:

but i really want to cover the whole area using the 3 towers using 3 freq.

Here is a quick sketch using all 3 frequencies on each of your 3 towers. Of course Canopy setups use same frequency and polarity on opposite sectors all the time but I showed dotted red lines to indicate where using opposite polarity would eliminate potential problems with some SMs.

The simple reason is that a very strong rssi SM on one side could swamp a very weak rssi SM on the other side. For example a -45dBm SM talking on one side while the opposite side is trying to detect a -70dBm SM.

Regarding your current setup, even if you don't see any problems right now running same freq (5730) on 3 adjacent sectors of tower 3, eventually there would be issues with some SMs for exact same reason: strong/weak rssi SMs falling on same slot. Adding 5730 on the 4th sector would only increase the probability.

wirelessdog

join:2008-07-15
Queen Anne, MD
kudos:1

That entire statement is incorrect. What experience do you base your assertions on?


robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1

said by wirelessdog:

That entire statement is incorrect.

It would help if you were a little more definitive. Out of the three paragraphs could you quote the incorrect statement?

wirelessdog

join:2008-07-15
Queen Anne, MD
kudos:1

1 edit

The statements are based on throwing out the advantages of ATPC, GPS sync, and every benefit given by Motorola.


robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1

1 edit

said by wirelessdog:

The statements are based on throwing out the advantages of ATPC, GPS sync, and every benefit given by Motorola.

Ok, so you are saying that lutful See Profile was incorrect when he stated

said by lutful:

Regarding your current setup, even if you don't see any problems right now running same freq (5730) on 3 adjacent sectors of tower 3, eventually there would be issues with some SMs for exact same reason: strong/weak rssi SMs falling on same slot. Adding 5730 on the 4th sector would only increase the probability.

Would you please clarify. It sounds like you are stating that it is perfectly fine to run four APs on one tower on the same frequency because of Canopy's magic sauce. Is this your opinion?

Jafster

join:2013-02-07
111111
reply to lutful

Thanks Lutful... The green colors are facing to each other you think it will work that way? i am assuming that the green color are on the same polarity and same freq.


wirelessdog

join:2008-07-15
Queen Anne, MD
kudos:1

How far are the physical towers from each other? Are you using the factor AP's with no modifications or are you using external antennas on your AP's?

Expand your moderator at work

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to Jafster

Re: How can i use single Freq. in 4 Canopy AP's in one tower?

said by Jafster:

Thanks Lutful... The green colors are facing to each other you think it will work that way? i am assuming that the green color are on the same polarity and same freq.

Yes, same color means same channel and polarity. SM antennas are usually more directional and there is no problem even if beams of same frequency and polarity cross each other while going to different APs.

The only problem that can happen in TDMA systems is a very strong SM in one sector swamping a very weak SM beam in the directly opposite sector. Think about the short fat red arrow SM directly opposite one of the long thin red arrows on tower 2.

I drew some arrows to show how you could assign same SM to different APs in the various frequency zones. The general goal of frequency allocation and sector antenna orientation is to maximize SM-to-AP pairing options. You will notice that the green frequency zone is actually the largest and most flexible.
Expand your moderator at work

Jafster

join:2013-02-07
111111
reply to wirelessdog

Re: How can i use single Freq. in 4 Canopy AP's in one tower?

Wirelessdog... the distance of my tower is not morethan 2 miles to each other.
with regards to my AP, i didnt do any modifications with the antenna.


Jafster

join:2013-02-07
111111
reply to lutful

Thanks lutful for your effort. i really appreciate. i will do a test with this setup.

"The only problem that can happen in TDMA systems is a very strong SM in one sector swamping a very weak SM beam in the directly opposite sector. Think about the short fat red arrow SM directly opposite one of the long thin red arrows on tower 2."

Do you know a way or additional configurations that can prevent or the above problem?


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

said by Jafster:

Do you know a way or additional configurations that can prevent or the above problem?

You can use ATPC feature available in Canopy/Alvarion to keep SMs below a maximum SNR value which allows the weakest SM on the opposite sector to operate with reasonable SNR.

You can also manually reduce TX power output for strong signal SMs ... which are usually at close range and aim towards the center of the AP's sector antenna beam pattern.

P.S. The best technical solution requires implementing system-wide scheduling so that SMs transmitting in the same time slot provide similar rssi values at their APs by adjusting their transmit power per slot.