The AP MAX distance questions

Greetings all,

So, I am wondering. I have all aps on one cluster set to Max Range 8 Miles (Range: 1–30 miles)

My farthest customer is 3.1 miles away, and I don’t see us ever needing to go further than that.

My question is, whatt happens if I lower my max range to say, 4 miles? Is there ANY benefit to doing this. What if we put it to 12 miles? Thanks!


Hi Yappa,

lol :slight_smile:

lets go through the theory, the further the SM is the longer it takes for the signal to get there and back, so if you have 2 sm’s, one 1 mile away and one 10 miles away, then the response from the first one will be quicker then the second.

Now if the AP is talking to both, it needs to send and receive from both at the same time, it does not want to be in a situation where the first one has responded and it decides to talk back to the first one, yet the second one is still sending, that way you would loose data becaouse the AP can only do one thing at a time, and also cause self intereference.

So the max distance setting is help the AP keep in sync and make variations in the guard time in the frame it generates, so the guard time in the frame destinied for AP1 will be diff for Guard time in frame for AP2. (no as simple as that as one frame can serve upto 3 different SM’s).

In thoery you should have the setting to actual MAx distance + 1, as this would conserve a data slot giving you in theory extra 200kbps throughput.

In reality, inconsistent, some people will get better performance applying logic, others at max distance and there are roumours of max distance -1 setting.

So know you have the theory, its trial and error.

Ok, I’ll set the auctual max (3.1) + 1. We’ll try four miles and see what happens. I assume I can just change this on the AP, reboot, and all will be cool?

thanks for your explanation.


Our farthest customer is out around the 7 mile marker. I set all AP’s in our system to 8 miles, but this started to cause issues with the links and link tests. Customers that normally tested 100% in both uplink and downlink suddenly dropped to anywhere between 90 - 100%, the average being about 94% in both directions.

These are still good stats for the tests, but for some reason, the only way I can keep 100% in both directions for all customers is if I set the Max Distance param to either 14 or 15 miles.

All hardware in the system is legacy 5.7 gear.

you had to double you distance to maintain quality links, which means my current setting of 8 miles for a the furthest 3.1 mile link might be perfect. I’ll run some link tests and let you know the results.


We have customers who have great signal levels but sometimes their jitter will spike. When Jitter spikes, does the SM “Appear” to be farther than it really is from the AP? Would this cause the SM to appear “idle” for an average of 25 seconds? We have the max set to 20 miles. But I am willing to set it further if it helps keep links up. OUr farthest customer is around 12 miles.

I have not learned the “why,” but here’s the what…

Regarding the 2x HWS feature:
In order for a SM to maintain 2x connections, its AP needs to have a maxrange value of at least twice the auctual distance that the SM reports.

IIRC, that was discussed in detail a while ago; couldn’t find the thread quickly though.

That could be related to your reduced link test performance.

I am running all Legacy SWS gear.

msmith wrote:
I am running all Legacy SWS gear.

Hmmmm, well there goes that theory.

I'll just reach into my trusty "bag-o-possibilities".... and pull out "That's not a bug, its a feature. Learn to live with it"

Oh wait, sorry. That was the "bag-o-micro$oft-excuses."

<<reaches into a different bag>>

"Wierd intermittant interferance"..... ahhh, that's better.


According to Canopy support, setting the distance to 10 miles on a 5700 (or 15 miles on a 2400) sets the AP to max power output. Lowering the max distance setting below the rated max distance lowers the output power (in small increments). I could not get a definitive answer as to how much the output is attenuated when set below the theoretical max.

In situations where you may have a relatively quiet RF environment you might be able to squeeze a little more distance out of the AP. However if you will never go past 5 miles, then there would be no point. Setting to 10 miles would be enough. Our situation is such that our closest possible customer is 2.5miles extending to 20 miles from the same tower location.

With that said, we set
5700’s at 15 miles
2400’s at 20 miles
900’s at 30 miles

this was a lotta info. so I started testing on my most unpopulated AP, which, not coincedentally, had a new client we have been STRUGGLING to connect. This client is 3.8 miles away and has a dish with P9 board on 5.7

I tried 4 miles. Numbers looked ok, but not as good as my default 8 miles. I could not connect to distant client.

I tried 10 miles. Numbers looked a little better, distant client still no show.

I tried 20 miles. numbers look still better (though subtle) and distant client shows up!

I tried 30 miles, numbers are best, distant client is up and has 1230/5/-72

I run the numbers one more time. 30 is still the best.

Does anyone know if this will produce unnecessary latency? I am so happy to get our trouble client up, I’m tempted to just leave the distance to 30!

What is the reported distance on the SM? My thought is that the link quality is poor, adding to the max distance setting decreases possible throughput. Since the throughput is less a poor link has a better probability of connecting.

Changing the max distance setting doesn’t adjust the power.

Someone mentioned setting the max range to 2x the actual distance when running in 2x HWS mode this is not correct.

VJ is correct in stating that you should keep the distance to your furthest SM+1 since you do lose data throughput as you increase distance. You can use the frame calculator in the extended statistics to see the data slot change when you increase or decrease the max distance setting.

here’s the stats on our trouble client:

Session Timeout: 0, AirDelay 371 (approximately 3.44 miles (18179 feet))
Session Count: 25, Reg Count 66, Re-Reg Count 37
RSSI (Avg/Last): 1121/1126 Jitter (Avg/Last): 5/4 Power Level (Avg/Last): -72/-72
DnRate(D): 256 DnLimit(D): 40000 UpRate(D): 256 UpLimit(D): 40000 (kbit)