C9115AXE Antenna gain setup

[SeokGeunChoi73564]

Hi, I have problem with C9115AXE Deployment.

Symptoms : Wireless client has good signal with C9115AXE with AIR-ANT2524DW-R, but cannot communicate to network. 

AP placed over the roof and the room is an explosion-proof area. I can't placed AP in a room.

(Client Performance : Signal Strength -55 dBm , Signal Quality : 40dB, Ch BW(Nego/Capable) 20 MHz/ 20MHz / Capabilities 802.11n -2.4GHz / Spatial Stream : 2)

The client loss many pings.

So I placed another AP for test, it placed in a room and client didn't loss pings anymore.

So I want to try to adjust AP Antenna gain, but couldn't understanding.

1. What is the most appropriate value for antenna gain? (C9115AXE-K with 4 AIR-ANT2524DW-R)
2. Do you think disabling some of the antenna parameters will help solve the problem rather than using 4 antennas?

+ The vertical distance between the AP and the user is at least 2.5M (approximately 8ft).

[Rich R · Accepted solution]

You can't adjust the antenna gain - it's fixed.
You have to enter the correct antenna gain (for that antenna) as specified in the datasheet on the controller.
If the room is explosion-proof the shielding is probably also blocking most of the WiFi RF signal.
You should look at getting an AP inside the room.

[Scott Fella · Accepted solution]

One thing to also keep in mind, just because the power or the ap + antenna is increased, the client power and antenna is not.  That means even though the signal strength from the ap looks good from the client side, does not mean that the client signal is good towards the antenna.  This is the same with outdoor wireless and antennas used to cover a large area.  The analogy is like a father and son throwing a ball, the father can throw to ball to the child, but the child is unable to throw it on a fly back to the dad.

Like what @Rich R mentioned, the antenna is fixed and the power is adjustable, but most likely you have it at max.  A good test is to place a test ap inside and then close up the room and see if you can connect back to the ap.  

[David Ritter]

You could also mount the AP on the roof, and extend the Antenna to the inside.  if there was a hazmat reason to keep the electrical parts outside of the containment zone. 

Note,  Maximum Effective Radiated Power (EIRP) is country limited. and changing antenna gain might not affect the eirp if already at legal limit.  As Scott said the AP antenna gain does not affect the Client.   However it does increase the Receive signal level.  and much more noise.

[JPavonM]

Have you checked the antenna polarization is consistent? I mean, is the antenna in the roof pointing downwards? This is very important as wrong polarization implies packet loss and retransmissions.

Have you checked there is no source of interference close to the AP on the roof?