Wireless Access

Having a strange experience with the AP-303H's deployed in a medical environment. The APs are deployed about half way into the rooms and about 4-7ft on the wall. When standing outside the patient door, no obstructions between me and AP, I'm seeing -65 to -70dBm signal on 802.11a radio (SSID is 802.11a only). The configured settings are 18 min 21 max, all running at 18 Tx power. Something seems seriously off. Some APs are running in Power-save mode at location A, but location B has same experience and no power-save mode on APs.

Does anybody have similar experiences or ideas? I've been looking into LLDP, but don't know if it's related.

I think full AT power only matters if you are using the USB port and you are powering a 803.af POE device.

I think those wallboxes were meant to only supply a single room's worth of coverage, and not much beyond..

Please get directly in front of it and measure the maximum signal strength.  Please also double check the transmit power.

EDIT: What are you measuring the signal strength with?

I've confirmed Tx power a few times, including "show ap tech-support" command and reviewing the data.

I wasn't sure if the AP isn't even pulling 15.4W, could that affect the ability of the radios to operate at 100%.

I will try to get in front of the AP itself, hard to get into patient rooms, most are full. Is there some type of data showing how far the signal can propagate in an open space at any given Tx power?

What are you measuring the signal strength with?   

The antenna plots are in the datasheet here:  http://www.arubanetworks.com/assets/ds/DS_AP303H.pdf

Please also see the power sources and consumption portion of the datasheet.

I typically measure with a phone - android with wifi analyzer app. Since phone radio should be weaker than most PCs, I figure it's the "weakest link" mentality. However, I have no issues with signal on existing AP-215's on ceiling, its just the 303H's that seem like something isn't operating at full strength.

First just to clarify, the POE status does not affect or restrict the transmit power of the 303H radios.

The transmit power value value that is (set or) reported in the UI is in terms of total EIRP, which means it includes MIMO gain and antenna gain. The antenna gain number is a peak number. Since the actual pattern fluctuates, the power in a particular direction could be a couple of dB lower. When seeing 18dBm in the UI, it is very well possible that the actual power in a particular direction is 15dBm or lower.

At 5GHz, the "free space pathloss" is about 67dB when 10m (30ft) from the transmitter. In a more realistic environment, that loss can be significantly higher. Assuming 75dB, you would expect to see -60dBm 10m removed from the AP (LOS).

Your receive antenna may have negative gain, introducing some more loss.

All - just wanted to close the loop on this thread. Basically the APs are functioning normally as expected. We've determined that signal loss is due to the enviroment, as well as the positioning of the APs and frequency of access points to rooms. We have tuned the radios to optimize signal strength and to ensure we do not introduce additional co-channel interference, we've also been able to enable DFS channels and lower our widths to 40MHz and 20MHz were appropriate.

I've spoke with multiple Aruba resources and all have confirmed the expectations of the 303H's are what we are seeing.

Thanks for all of the input and feedback.