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Testing and Mapping a Cellular Data Network?
bgsneeze writes "In order to resolve an ongoing issue with a vendor, I have been trying to find a way to test different 3G data devices empirically. I would like to be able to chart signal strength, latency, and bandwidth. I would also like to create a map of the coverage area. I have a test 3G card from three different providers. I would like to be able to travel with the setup to several different locations and run tests. What software or techniques would Slashdotters use to test the different devices? Are there any free or open source software packages that will do this?"
http://www.mytruecoverage.com/ is a good site to show coverage. You can install an app on your phone then manually run tests. The results usually take 12-36 hours to post to the website.
Empirical testing with wireless CELLULAR networks can be very tricky; A few things that you will need to keep in mind is that for testing, you want to make sure your transceiver setup is perfectly reproducable; Same card, same ANTENNA, same position of antenna. When performing your testing, your signal strength will depend on several factors: Distance from the site, antenna type/gain, and specifically what sector/node on the site you happen to be on. while driving in a straight line, you may find that you approach steep nulls near the border of a cells sector boundary. Alot depends on the ability of your particular card to handle the handoff between sectors/sites.
Your latency measurements will also vary according to the individual usage of the sector/site that you are currently on, and additionally vary with time and also variable bandwidth allocation to the sites from the main switch.
There are quite a few test sets and software suited that are commercially available and are tailored for this use, and are used heavily by the mobile data/cellular industry in their drive testing and coverage verification methodologies.
Good luck to you on your testing.
--ToO
Industry standard?
http://www.qacafe.com/cdrouter
In the end, the project was cancelled before we got a chance to get to test 3G coverage. But we did get to think about it. Our customer was a fleet of cargo ships, going through a fixed path on the Rio de la Plata (River Plate). Basically, we were going to install our CCTV system in there, and have it push images and other information to our servers whenever it had signal. We wanted to know approximately in what areas of the river we would have signal. We were going to base our system on the Vodafone mobile connect driver. It's a set of Python scripts. Of course, it communicates with the modem using simple AT commands. It's released under the GPL. It is capable of measuring signal, sending and receiving text messages, and other nice stuff (like, well, actually dialing and calling PPP to stablish the connection). We had it working with several Huawei devices, but I know it works with other brands too.
Our idea was to modify this scripts so that they would try to maintain a connection, auto-dial every time it disconnected, and log the signal at certain intervals to a MySQL DB. We were also going to run download tests all the time automatically. Since there was no chance we would go on the ships with the devices (the ships were cargo ships that transported and extracted sand, and there weren't very comfortable, not to mention their average trip was at least ~72 hs.), so we wanted to do all of this automatically. The devices would also inform their IP to a web service every time their IP changed, so we could SSH in the machine running this tests in case we needed to change something.
We were going to add a GPS to this system, that would also log its position at certain intervals, so that we could then generate a color-coded signal map.
I hope this helps. It's really fairly simple. I would be happy to provide you with source code, but we didn't get that far into the project as to produce actual source code, since the customer changed his mind due to budget restrictions real early. Feel free to contact me if you have other questions {almafuerte (at) gmail (dot) com}
WTF am I doing replying to an AC at 5 A.M on a Friday night?
A bigger number on the same device probably means you have a better signal. A 'two' on one device could be equivalent to a 'five' on another or a 'one' on a third. There is no standard that is used across the industry, or even across all devices from a given manufacturer.
When a device manufacturer gets customer reviews that say "I only get one bar with your phone but two from company X" the device manufacturer can either try and explain repeatedly that their one bar is better than X's two bars and that unlike X you can still make phone calls on our device on one bar. Or they can just double the number of bars reported on the next model so they don't look worse than X.
Which do you think they do?
To do a real test you need to use a constant antenna and location, attenuating the signal gradually until each device stops functioning. The amount of attenuation it can take is a crude indicator of the quality of the radio.
Dan Williams, the guy behind Network Manager, does a lot of work to get cellular modems working in Linux. There seems to be lots working and steady process on others.
His blog http://blogs.gnome.org/dcbw/ is informative and frankly pretty hilarious in a geeky way.
Props to Dan for doing a great job.