What is the max distance between ap units

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Wondering what the max distance is that i can put between ap units or is it based on the ap units them selves 
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Dan

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Posted 4 years ago

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Harmon Oostra

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Hi Dan,

It's based on a couple of things. 
Are the Ap's seeing each other or is there a brick wall in between?


Regards,

Harmon
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John Fabry

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outdoor; type of antennas, foliage, background noise (noise floor), distance, required throughput are just a few items that impact how far away the radios can be.

Indoor; wall composition, required throughput, number of users (capacity planning), types of traffic, radio frequency needed (2.4 v 5), number of water bags (people) in the room, possible interference sources, transmit power level of AP, antenna orientation, type of AP, all can impact indoor deployment.
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Ernie Johnston

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It depends, on how much speed and throughput you need. A quick chart is available from Cisco here: http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-3600-series/white_paper_c11-713103...

Go to section 2.3.7 Rate at Range, examine the chart, then double that or less, depending upon your facility (free space, concrete walls, etc.)
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Rob Ceralvo

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Thanks Ernie.
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Dan

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thank you all for the info
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Nick Lowe, Official Rep

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I think you're thinking about this in the wrong way, you definitely will not want to put APs at the theoretically maximum distance apart for your client set where they can still maintain an association, but only with the lowest data rates. The capacity, performance and reliability would be abysmal.
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David Coleman, Official Rep

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Distance depends on the antennas used, transmit power of the APs, and the attenuation factor due to Free Space Path Loss and the materials that the walls are made of.  A better question should be about the clients hearing the APs. A client connected to an AP should be able to hear a -75 dBm or better signal from two other APs so that the client can roam.   On the flip side, it would be bad if a client can see strong signals from dozens of APs.  That would indicate that too many APs have been deployed and.or they are transmitting at full power. APs should transmit at half power or less in most design scenarios,
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Dan

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thank you for the information but that does beg the question why is at half power better? 
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Stefan van der Wal, Champ

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There are various reasons for using half power on AP's but for me these are the main ones:
- Avoiding deadspots; when one AP fails. when using half power, other AP's can increase their transmission power to take over cover from a failed peer.
- Communication with clients (in general); WiFi is a two-way street where the AP's have high quality radio's that can send and receive much better than a client could. For instance if an AP has power 20dbm (max. output) and a client can only output 17dbm the client will simply not reach the AP. It's kind of like one person screaming over a long distance while the other can only manage a whisper.

I could give you more, but I don't really know what sort of deployment you're looking at.
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Crowdie, Champ

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Another common issue with wireless networks where the access point's transmit power is too high is poor roaming.  One of the symptoms of poor roaming is that users report low signal levels and the IT team responds by installing additional access points, which makes the problem worse not better.
(Edited)
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David Coleman, Official Rep

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Access points at too high of power can cause MULTIPLE issues:

1) Co-channel interference
2) Roaming problems - sticky client
3) Capacity needs are not met
4) Hidden node problem
5) Possibility of low-powered clients not being heard by the AP

One of the most common errors is to blast APs at full-power
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Sjoerd de Jong, Employee

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Oh yes, I occasionally run into troubleshooting scenarios where the radio's are fixed on 20dBm because 'the more signal strength the better' :-O .

It's almost the same as 'yes i use different channels on my AP's!, AP #1 is on channel 1, #2 is on 2, #3 is on 3..' etc. I guess it keeps our job dynamic!