Can’t trust Cell coverage maps? Make your own!

July 1, 2015 at 8:39 am Leave a comment

At my day job, I’m responsible for the network connectivity for hundreds of remote locations.  We use 3G today as a backup to our T1 circuits.  One thing most IT people who have tried to put in a cellular network can probably attest to:  Vendor provided cellular coverage maps absolutely suck.  Even if you give the vendors a list of your addresses, you’ll get a far rosier picture of the coverage they can provide than exists in this reality.

So, what do you do when the vendor provided data isn’t any good?  

You make your own!


We’ve taken a small plastic tub, a consumer grade 5 port Ethernet switch, three CradlePoint CBA850’s, and a Quirky power strip to handle the huge power bricks the CBA850s need.  We’ve mounted the power strip to the bottom of the tub,  the switch to the side of the tub on one end, and the three CBA850s to the sides, so that their antennas fold down just below the top.  The CBA850s are pre-wired to the Ethernet switch, along with an extra CAT5 cable about 10 feet long.  The CBAs and the switch are plugged into the power strip.  The CBA850s are configured for AT&T, Sprint, and Verizon, so we can get a good picture of the coverage of all three carriers.  They are configured with static IPs not used elsewhere in our locations.  When our technician arrives at a location, he removes the top of the case, folds up the antennas, finds a power outlet and a free Ethernet port and plugs in.  A quick call to our NOC to let them know which location he’s at and which port to turn up is all that’s left for the tech to do.  At that point, our NOC staff can kick off a script which updates the router config for that location to NAT the CBA850s to addresses specific to that store, allowing them to be reached from headquarters.

Then, using the API magic I mentioned in my last post, the script validates that all three CBA850s are reachable, then it checks in with them to see if the WAN is connected, waiting around 5 minutes for any stragglers.  Once they are all up, or the expiration time has passed, it kicks off a series of speed tests, both upload and download, gathering the results of the tests along with other diagnostic info (SINR, signal strength, etc).  Drop that data into a database table, and there’s our “map”.

That’s no MAP!  That’s just a bunch of numbers!

No, our “map” won’t look like a map, but it will have data telling us which of the three main cellular providers is the best at every one of our locations that we’ve tested.  From the perspective of our management, that’s really all that matters.


Entry filed under: CradlePoint, Networking.

CradlePoint API info CradlePoint and NTP

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