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Jafster

@80.92.49.x

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

I am newbie in canopy and i am trying to use a single frequency in my 4 AP's in my tower, but when i do assign the same frequency in to two side by side AP the SM located at the edge of the two AP keeps on disconnecting. i notice the the SNR goes down.

Please help. thanks a lot



slythesis

@charter.com

Canopy allows channel re-use on back-to-back APs, with appropriate timing parameters of course. So it might be difficult to achieve your goal with just one channel....maybe narrow up the beamwidth on your APs?
Doing so would cost you coverage area of course.


wirelessdog

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

You can get away with two channels, not one. Are you GPS synced?



DaDawgs
Premium
join:2010-08-02
Deltaville, VA
reply to Jafster

It is my experience that one AP can service about 50 customers without too much overload.

Do you *REALLY* need 4 APs on that tower?

Canopy will have severe problems if you try to overlap 4 APs on the same channel on the same tower, as would any other technology. It is just a bad idea, period.
--
Once we IPv6 enable every device on the Internet we will have toasters, baby monitors, and security cameras joining the bot nets which today are populated only by idiots that can not refrain from clicking, "Yes I would like to see those titties..."


Jafster

join:2013-02-07
111111

1 edit
reply to wirelessdog

Yes i have a CMM4 and a GPS, currently i am suing two freq. per tower but i really need to change it into one.

and i have 4 AP's in sa single tower already and we need that setup atleast cover the place.


Jafster

join:2013-02-07
111111
reply to DaDawgs

well i hope i can do that. problem is that we want cover 120 deg. and that is the reason why i/we want to use a single freq.

i hope that there is a way to solve my problem.


Jafster

join:2013-02-07
111111

im sorry what we want is a 360 coverage using 1 freq.


Chessie

join:2011-02-02
united state

said by Jafster:

im sorry what we want is a 360 coverage using 1 freq.

you will not be able to do that using multiple AP's.

you can do it with a single AP and and omni antenna.

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

If you really really want to run 4 separate APs on a single tower ... there is only one reasonable solution to minimize the interference.

Change the polarization of 2 of the APs and their SMs. So opposite APs run same polarization while adjacent APs run opposite polarization.


Chessie

join:2011-02-02
united state

said by lutful:

If you really really want to run 4 separate APs on a single tower ... there is only one reasonable solution to minimize the interference.

Change the polarization of 2 of the APs and their SMs. So opposite APs run same polarization while adjacent APs run opposite polarization.

would that allow him to run the same frequency side by side though?

wirelessdog

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

It might work. Or you could switch to connectorized AP's and two 180 degree sector antennas which would probably give you better performance anyway.

Lets take a step back.

Why do you feel the need to use one frequency? Post some screen shots of your spectrum analysis.


Jafster

join:2013-02-07
111111
reply to Chessie

Chessie, if we can change the polarization do you think we can use a single frequency for 4 ap's in a tower?


Jafster

join:2013-02-07
111111
reply to wirelessdog

wirelessdog we dont have enough freq. we are allowed to use only 3 frequencies but we have 3 Towers so i want to use 1 freq. in each tower. our towers are 1 to 2 mile apart.


jakkwb

join:2009-04-27
USA
reply to Jafster

If all three towers can see each other, and they are that close, I would just use one of them only and use 4 sectors. That way you can reuse the channels that are back to back. So, the tower uses 2 channels instead of 3. You will have far less trouble with sectors instead of a single omni.

This way, you can use the other two towers for other freqs, if you want.


wirelessdog

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

Three frequencies split between three towers will work fine. You need to make sure everything is properly synced and use frequencies correctly.


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

said by Jafster:

we dont have enough freq. we are allowed to use only 3 frequencies but we have 3 Towers... 1 to 2 mile apart.

Your situation is not that bad really. You don't even need any opposite polarity sectors if you used 3 sectors per tower.

If you must have 4 sectors per tower, have a look at above sketch for some ideas on how to orient the sectors to minimize interference from same frequency AP on another tower.

wirelessdog

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

Apples and oranges. We are dealing with Canopy in this application. Throw everything you know about 802.11 out - it doesn't apply.

The diagram, while it is helpful on a non-canopy setup, really doesn't apply to the OP's situation.


jcremin

join:2009-12-22
Siren, WI
kudos:2

said by wirelessdog:

The diagram, while it is helpful on a non-canopy setup, really doesn't apply to the OP's situation.

Please explain further... I've never used Canopy myself, but it seems a layout like the diagram shows is simply efficient use of spectrum regardless of the technology used. I would assume anytime you can avoid having towers blasting each other on the same channels is good practice, GPS sync or not, although I am aware that the GPS sync makes it much less critical than 802.11....

wirelessdog

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

Canopy GPS sync allows one to reuse the same frequency twice on each tower. That would be 2 frequencies per tower for the OP. The OP has a total of three frequencies available. The frequencies can be reused on each tower as long as the AP's are not facing each other. Heck, the AP's can truthfully probably be facing each other without any service issues. This is why competing Canopy WISP's can live in each other's territory so efficiently as long as the coordinate things like dl%, control slots and range.

This is how we can run six 60 degree 900mhz sectors per tower with only three non-overlapping frequencies. It is also how channels can be used over and over and over again.

To the OP: The question still hasn't be answered if your towers are correctly GPS sync'ed. Based on your questions I would guess not so I would suggest a starting point of posting a simple diagram of your network along with your dl%, control slots, and range/distance settings per tower and exactly how you do GPS sync per tower.


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

1 edit
reply to wirelessdog

said by wirelessdog:

Apples and oranges. We are dealing with Canopy in this application. Throw everything you know about 802.11 out - it doesn't apply.

I do understand how Canopy (gps) sync actually works and the gotchas. The sum of the received power from other sectors may swamp an AP because SMs also transmit at the same time.

P.S. I recall you participated in this 2010 Canopy thread.
»Argh! What is doing this?!

wirelessdog

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

Its hard to remember who understands canopy and not with the flood of the UBNT noobs.

That being said, I stand behind your diagram being incorrect for the application.


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

said by wirelessdog:

I stand behind your diagram being incorrect for the application.

You could draw a correct diagram for this application? If it uses same frequency in same direction, you will have to consider the scenario shown above.

said by wirelessdog:

Its hard to remember who understands canopy and not with the flood of the UBNT noobs.

Some Canopy fans are worse than Ubiquity fans because of their "blind faith" in GPS synced TDMA.

P.S. If you search my old posts for TDMA and FPGA, you will see references to a radio platform (my company) designed in 2004 before Canopy added FPGA and a Canopy clone with better spectrum sharing features in 2006. I disclosed recently that (my new company) has developed a TDMA system designed from scratch for HD IPTV delivery.

LLigetfa

join:2006-05-15
Fort Frances, ON
kudos:1

That diagram does not describe what the OP said. For the OP the problem is one SM sitting out on the edge between two APs on the same tower.

The multiple tower scenarios are all conjecture since the OP did not say where they are situated relative to each other.

I think the other SMs and other towers are not contributors to the problem. The SM sees two APs on the same tower, both with about the same signal strength, both on the same frequency and polarity.

Instead of trying to get four APs on a tower, all on the same frequency, he should try only using the same frequency on back-to-back APs, so two frequencies per tower. Of course then the two other towers come into play so he needs to plan his frequency reuse between towers as well.
--
Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey


aeronet

join:2002-04-05
San Juan, PR

If you post a sketch of you towers locations we might find a good freq plan for all 3 towers using the 3 channels. also inlcude the 3 exact channels


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

said by LLigetfa:

The multiple tower scenarios are all conjecture since the OP did not say where they are situated relative to each other.

The exact distances between towers (AB/BC/CA) will not make much of a difference since the 3 towers are located 1-2km from each other. He really wants to run 4 sectors on each tower and he wants to use all 3 frequencies available to him.

My suggestion on previous page is a good setup considering all known factors. If you disagree, post a sketch showing what sector/frequency allocation may work better.

LLigetfa

join:2006-05-15
Fort Frances, ON
kudos:1

said by lutful:

He really wants to run 4 sectors on each tower and he wants to use all 3 frequencies available to him.

Not quite. Yes, he wants to run four sectors but he wants to run all four sectors on the same frequency. He wants each tower to have its own frequency.

As for the distances between the towers, they are not a factor under his current config since each tower has a unique frequency. It only becomes relevant if he decides to use the same frequency on more than one tower. Then the placement must take into consideration all factors.

There are so many permutations possible that it is senseless for me to post sketches based on conjecture. Maybe the towers are all on the periphery and no SMs would see two or more towers? J/K
--
Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey

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

said by LLigetfa:

he wants to run four sectors but he wants to run all four sectors on the same frequency.

Yes, he wanted to do that but obviously that won't work very well even with GPS sync and excellent front-to-back ratio sector antennas.

There would be interference contribution from 3 SMs (belonging to the other 3 APs) in every time slot. When some or all of those SMs are located at shorter distance from the tower than the target SM, noise may rise above expected RSSI.

People already suggested using a single omni antenna or 2x 180 degree sectors or a 1:4 splitter at each tower to meet his original desire to run one frequency per tower.

Using all three available frequencies at each tower to maximize his total wireless network capacity is just another option.

LLigetfa

join:2006-05-15
Fort Frances, ON
kudos:1

said by lutful:

Using all three available frequencies at each tower to maximize his total wireless network capacity is just another option.

Yes but using only two frequencies per tower might also be an option and may in fact make channel reuse easier.

Until such time that the OP gives us more details, it is mostly conjecture.
--
Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey

aeronet

join:2002-04-05
San Juan, PR
reply to Jafster

in need tower placement to properly produce a channel reuse plan, is not the same to work with 3 towers in straight horizontal line that a triangle setup.... My plan is 2 channel per tower, A/B A/C B/C ...

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