Topic 'How can i use single Freq. in 4 Canopy AP's in one tower?' in forum 'Wireless Service Providers' - dslreports.com

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

Tue, 12 Feb 2013 16:42:04 EDT

lutful posted :

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.

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

Tue, 12 Feb 2013 15:35:52 EDT

Jafster posted : 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?

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

Tue, 12 Feb 2013 15:33:24 EDT

Jafster posted : 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.

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

Tue, 12 Feb 2013 14:01:48 EDT

lutful posted :

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. :)

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

Tue, 12 Feb 2013 08:08:26 EDT

wirelessdog posted : 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?

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

Tue, 12 Feb 2013 01:53:09 EDT

Jafster posted : 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.

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

Mon, 11 Feb 2013 23:11:37 EDT

wirelessdog posted : No, I'm saying it is possible and acceptable and run four sectors on multiple towers reusing the same two frequencies.

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

Mon, 11 Feb 2013 23:05:06 EDT

robbin posted :

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 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?

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

Mon, 11 Feb 2013 22:11:23 EDT

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

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

Mon, 11 Feb 2013 20:55:27 EDT

robbin posted :

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?

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

Mon, 11 Feb 2013 13:23:58 EDT

jcremin posted : Take it easy guys... you're arguing about answering a question that hasn't even been asked with enough details to give an accurate answer... and on top of that, there may be multiple answers that are just as appropriate for the situation, if the OP ever comes back and finishes explaining it....

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

Mon, 11 Feb 2013 10:23:56 EDT

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

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

Mon, 11 Feb 2013 10:02:58 EDT

lutful posted :

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.

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

Mon, 11 Feb 2013 04:45:34 EDT

Jafster posted : 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.

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

Mon, 11 Feb 2013 04:22:04 EDT

aeronet posted : 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?

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

Mon, 11 Feb 2013 02:15:58 EDT

Jafster posted : 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.

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

Mon, 11 Feb 2013 00:25:57 EDT

LLigetfa posted : Lutful,
Your drawing suggests two sectors per tower but the OP wants four. Two channels per tower with four sectors would mean reusing the same channel back-to-back so North and South may be A while East and West are C.
--
Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey

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

Mon, 11 Feb 2013 00:00:26 EDT

lutful posted :

said by aeronet:

3 towers in straight horizontal line that a triangle setup.... My plan is 2 channel per tower, A/B A/C B/C ...

If the towers are close together, both APs of the middle tower may see higher noise when communicating with SMs towards the edge.

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

Sun, 10 Feb 2013 21:03:39 EDT

aeronet posted : 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 ...

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

Sun, 10 Feb 2013 17:28:09 EDT

LLigetfa posted :

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

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

Sun, 10 Feb 2013 17:03:17 EDT

lutful posted :

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. :)

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

Sun, 10 Feb 2013 16:23:06 EDT

LLigetfa posted :

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

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

Sun, 10 Feb 2013 15:52:20 EDT

lutful posted :

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. :)

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

Sun, 10 Feb 2013 12:05:49 EDT

aeronet posted : 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

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

Sun, 10 Feb 2013 08:46:08 EDT

LLigetfa posted : 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

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

Sun, 10 Feb 2013 04:26:20 EDT

lutful posted :

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. :D

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.

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

Sat, 09 Feb 2013 23:51:08 EDT

wirelessdog posted : 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.

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

Sat, 09 Feb 2013 22:56:53 EDT

lutful posted :

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?!

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

Sat, 09 Feb 2013 22:25:06 EDT

wirelessdog posted : 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.

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

Sat, 09 Feb 2013 21:05:24 EDT

jcremin posted :

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....

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

Sat, 09 Feb 2013 20:21:51 EDT

wirelessdog posted : 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.

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

Sat, 09 Feb 2013 08:28:30 EDT

lutful posted :

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.

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

Fri, 08 Feb 2013 23:48:21 EDT

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

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

Fri, 08 Feb 2013 16:53:09 EDT

jakkwb posted : 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.

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

Fri, 08 Feb 2013 13:51:32 EDT

Jafster posted : 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.

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

Fri, 08 Feb 2013 13:48:38 EDT

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

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

Fri, 08 Feb 2013 11:22:33 EDT

wirelessdog posted : 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.

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

Fri, 08 Feb 2013 10:15:48 EDT

Chessie posted :

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?

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

Fri, 08 Feb 2013 09:46:21 EDT

lutful posted : 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. :)

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

Fri, 08 Feb 2013 08:36:24 EDT

Chessie posted :

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.

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

Fri, 08 Feb 2013 06:57:23 EDT

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

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

Fri, 08 Feb 2013 05:26:41 EDT

Jafster posted : 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.