Omni Vs Directional Antenna coverage

[WiFiOnHHI]

Kudos to this form! I've seen lots of great posts and answers given that have addressed several of my questions.


My question today deals with antennas and coverage.

I have a project for a local university comming up where my coverage area is a building that's shaped like the Letter H.
I was on site today putting in a cloubris CN2300 with basic rubber 1.5db antennas, and testing the coverage area with my laptop. The doodle below gives an idea of the building lay out.
It's two floors, with network closets marked by the *. Today I placed the AP in the closet on the second floor, and shut the door I recorded the following results: + = good signal, - = poor.

1st Floor
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- - + + + *+ ||||| + + + - - - - - - - - - -
+|||||+
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2nd Floor
|||||||||||||||||||||||||||||||||||||||||||||||||| ||||
++++++++*AP + ||||++++++++++-+-- +-
+||||+
||||
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So, I want to cover this whole building, wiring and AP locations are not an issue, I can put them anywhere, and use power over ethernet.

I was thinking at first, just putting in 8 Access points. Then i caught this website, and Im now thinking that would be ludicrous.
Some better antennas here would surely do the trick.

I was thinking 1 AP with a Directional antenna per hallway. Im guessing that should be able to get into the rooms and hit everyone, but I wanted some input from others on what kind of converage you can expect from that, and what level of gain antenna would work best. The hall is about 40 feet wide and 100 yards long. Also, would one 5db omni in the middle be enough to cover it? just looking for input there, ill find out soon enough.

Another question,
When using the little rubber antennas, does vertical vs. horizontal positioning affect the coverage?

Any input is appreicated.

Thanks!

[golfnut]

Hi WiFiOnHHI,

No one could answer that question without seeing the site. There are too many factors to consider like the number of walls the signal needs to go through, metal fire doors, number of users, glass, appliances, metal ducts, etc.

If this is at University (dorm?), you can count on a lot of bandwidth draining music and video downloads. You may want to consider controlling bandwidth.

Guess work cannot be part of a site survey, otherwise the final results will not come close to yours or your customers expectation. You need to know the exact coverage and performance based on antenna/AP placement.

I would suggest investing in a variety of antennas and testing the signal from locations (all locations) that will give you the coverage required for the environment. Don't assume anything.

You may also consider using APs with clear channel select assuming that some people will have their own WLANs crossing cells on channel 6.

It's a lot of work but it will pay-off in the end.

As for those rubber omni antennas. Imagine placing a doughnut over the antenna. That dougnut is basically the path of your signal and would move as you move the antenna.

Good luck,

Greg