Wireless site survey requirements

[cbarras]

Dear all

I need to execute Passive Site Surveys in order to get the wireless network design for different "only-wireless" offices. I have these requirements:

• 5GHz as primary frequency band. 2.4GHz available for legacy devices.

• 802.11ac Wave 1

• 20MHz (40MHz channels are possible in low density AP areas)

• -65 dBm minimum signal strength

• 25 dB minimum SNR

• 25% RF Coverage Overlap

What do you think about the 25% RF Coverage Overlap? Are you using this cell overlap in your new deployments or still with 20%?

Thanks in advance.

Best regards,

Carolina

[mohanak]

Check the site survey to determine whether the channel overlap is adequate for devices to roam to the next AP before the signal is lost from the previous AP. For example, based on the RF guidelines specified, you must use non-overlapping channels and allow at least 20 percent overlap with adjacent channels when phones are deployed in the 802.11b/g environment. For voice deployments, it is recommended that the cell edge should be at -67 dBm with 20 percent overlap.

[Rasika Nayanajith]

which site survey tool you use ?

[cbarras]

Ekahau or AirMagnet, not decided yet.

[Rasika Nayanajith]

If you use Ekahau, I would check the 2nd strongest signal and see the given area is covered  close to -67dBm.

I do not think you can accurately measure % of overlapping in practice.

HTH

Rasika

[cbarras]

Thanks Rasika!

[Freerk Terpstra]

Don't forget to survey with the weakest client in mind! Look at the attachment for a example with three different VoWLAN clients (Picture originally from George Stefanick).

[rbncarvalho]

10, 15 or 20% or cell areas is not easy to calculate (although there is an equation for that; if you want your overlap to be 10%, walk to the point where the AP signal is at what you want for your cell edge, i.e. the point where you want your client to be able to discover the next AP, measure the distance to the first AP; the next AP should be about 1.6 times this distance,; for 15% overlap, next AP is at 1.5 the first AP cell useful radius, 20%, next AP is at 1.4 times the cell radius, etc.). This paper explains how this is calculated:

http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Mobility/vowlan/41dg/vowlan41dg-book/vowlan_ch3.html#wp1059100