Pretty sure the FCC would accept this if you did enough samples to prove the
RF model.
-----Original Message-----
From: Brian Webster
Sent: Thursday, February 04, 2016 11:47 AM
To: af@afmug.com
Subject: Re: [AFMUG] Drive Testing
The most practical way to accomplish this would be to just validate your RF
model assumptions and then apply them to the fixed wireless propagation. As
you mentioned there is no practical way to test 22 foot CPE install heights
let alone the additional gain that a fixed CPE antenna provides as compared
to some sort of radio you could practically have on a mobile platform. While
you could go out and spot check with a push up mast that can be time
consuming when it comes to gathering a significant number of sample points.
The easier method would be to run an RF propagation with CPE parameters of a
device you can install on a mobile unit and drive around with. You could
then drive the areas that you predicted this coverage for and gather that
data in a text file. Ideally you would do the same drive multiple times and
under various climate conditions and seasonal changes. This would give you
sample points that you can compare the measured to the predicted. I would do
this in a GIS platform and create a delta table and map showing variations
between predicted versus measured. I would also have the data for each
clutter/tree class. This would allow me to investigate to see if there are
consistent delta differences and if they only appear to be variations with
certain clutter or if they predictions are off consistently for the whole
predicted area. This would then point me in the proper direction to make
changes in my RF tool, system wide would mean change the percentage numbers
in the mode of variability (fade margin), major differences in the delta for
various clutter classifications would tell me I need to adjust my
clutter/land cover file settings. Once the model is tuned to your
satisfaction you can then run your fixed CPE propagations with a lot better
confidence factor.
One thing to look out for though is the land cover data being used. I have
both the latest and the next oldest clutter data for North America. There
was some sort of formula change to the data in the latest release that
created some decent sized changes in various parts of the country, this
means your predicted coverage may be assuming trees or lack of in areas that
the reality is different than the land cover data. You can get a Google
Earth file that shows the current vintage land cover map/classification but
I am not sure you can do the same for older versions. I am fortunate enough
to have all of the data on a hard drive and can easily switch between the
two and compare differences.
Sometimes the old version is better, sometimes it’s the newer version, it
depends on your location. Sometimes there are clutter classifications for an
area such as Urban that you would not expect and thus your model is applying
losses for a clutter class you are not seeing in real life. I have attached
a Google Earth file with three separate areas in the US that have a new and
old clutter map version for the same spot, you can turn them on and off at
will while looking at the aerial imaging to see what the differences may be.
Thank You,
Brian Webster
www.wirelessmapping.com
www.Broadband-Mapping.com
-----Original Message-----
From: Af [mailto:af-boun...@afmug.com] On Behalf Of Adam Moffett
Sent: Thursday, February 04, 2016 12:11 PM
To: af@afmug.com
Subject: [AFMUG] Drive Testing
I was thinking about this during my drive to work today, and the
towercoverage.com thread just reminded me.
Is there a realistic way to do drive testing for fixed wireless?
I've plotted coverage using a 22' subscriber height, and I can't drive
around with a 22' high mast (vehicles and loads have a 13'6" height limit in
NY State). So rather than collecting data as I drive --which would be
relatively painless-- I'd have to stop, deploy a mast, record coord and
reading, un-deploy mast, move to next test point, repeat.
I think I could set a drone to a 22' flight ceiling. I'd still have to
drive the drone to different places because it will only work within range
of the controller.
Or maybe forget about drive testing.....is there a realistic way to validate
your coverage map other than attempting installations and seeing which ones
work?
If you're wondering why, I've been asked by some officials "how do you
validate this coverage projection?" All I've really got is that we attempt
installs and they usually work where they're supposed to.
