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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?"
Obviously this can only be used for terrorism.
http://www.cellularmaps.com/coverage_finder.shtml
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.
I assume that you are not working with a network operator? They have plenty of tools to do drives and plot out signal. Also, chip makers have these tools. I used to work for a large mobile phone chip maker and we had internal test setups that can be driven around in a car to plot signal, etc. Also, we developed a small device FPGA based device that could be tuned to various channels and recover the "sync" and "paging" channels of a CDMA system. You could do the same for UMTS, EVDO, etc. If you just wanted raw signal strength, all you really need is dBm for whatever provider and tower you are looking at. You could then compare strength between providers. However, this isn't really apples to apples. CDMA based systems can literally pick up signal out of horrid conditions and low signal powers... much than, say, a GSM based system. So if you were comparing purely 3G to 3G, that would be valid, but not in the 2G realm. Just get a phone for each provider, turn on the engineering mode to get the phone's reported dBm reading, and then plot the values as you drive around....
Why do it yourself when you can just wait for Google to announce they did it accidentally ;-)
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
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?
I would suggest the "grad student technique".
Find a nearby university and convince a professor to lend some (under)grad students to your cause.
It helps if you have friends that can refer you to professors/students who'd be interested in the challenge.
P.S. The only thing better than the "grad student technique" is the "summer intern technique"
[Fuck Beta]
o0t!
Can you ping me yet?
How about now?
At least, this is what I see working with SNMP data coming off dumps from the cellular base transceiver stations attached to our towers.
Every 15 minutes, every GSM handset measures the perceived strength of the tower signal it is using, this is reported to the tower, and we record them all. Also every 15 minutes, the strength of the handset signal, from the perspective of the tower is sampled and recorded.
These readings go into buckets, for example if a reading showed a -78 dbm signal, it goes in the -78dbm bucket. Before long, a histogram can be generated with the datain the buckets, and we can see typical distribution for receive performance - for both handsets and the tower. Different towers have very different "signatures" in this data.
You may go around sampling receive performance, (which would be interesting) but I don't think you'll be able to map how well the cellular system is receiving from you.
I would suggest learning that it's pointless to test for something you can't fix. You'll waste much less time and energy.
Your provider won't care even a Tiny Iota about your results. If you show that their network is fine, they'll ignore you. Even if you prove their network is not fine and all the packets are routed though a Sinclair ZX80 in Clive's basement they'll still ignore you. If you're really lucky, you might get a nice, polite "Fuck you very much, We're not fixing it."
Knowledge is knowing that they have 3000ms latency between nodes. Wisdom is knowing that the only thing you can do is vote with your wallet.
I wouldn't worry about charting the signal strength for 3G. You can be in a densely populated area showing five bars of 3G and your speed and latency can still be dog shit depending on how many people are hitting the tower, similar to your cable modem. It might be worth it to record whether or not you have 3G just to help map out your general coverage, but that doesn't mean you'll have great speed. Although, you can find something like that here.
As for speed I like to use a util called iperf for measuring speed from one device to another across a network. You may have to open ports on your firewall or setup a VPN, which will add unwanted overhead, but you will get a good idea of which carriers have the best speeds. You can also run the simple tests using other websites like here or here.
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Industry standard?
http://www.qacafe.com/cdrouter
If you mean the USB/PC card 3G adapters for computers, I doubt you'll be able to run them on Linux without using WINE or a VM or whatever, which may interfere with latency readings...........Note: too lazy to dig up hacks and testamonials from Google.
Sigh.......this is the kind of misconception that happens when you are too lazy to use Google. Those USB/PC card 3G adapters for computers work quite well on Linux, here is one example tutorial. Try not to give advice if you are too lazy to verify it.
Qxe4
http://www.sensorly.com/ Run it on your phone manually (or have it triggered intermittently). The 3G, EDGE and wifi coverage that your phone detects is uploaded to the central server and within a minute your phone receive the updated maps. You can only contribute to the maps for your phone's carrier, but you can view the maps for all carriers.
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?
http://www.cs.wisc.edu/~suman/pubs/citywide.pdf
ABSTRACT
We describe our experiences in building a city-wide infrastructure for wide-area wireless experimentation. Our infrastructure has two components — (i) a vehicular testbed consisting of wireless nodes, each equipped with both cellular (EV-DO) and WiFi interfaces, and mounted on city buses plying in Madison, Wisconsin, and (ii) a software platform to utilize these testbed nodes to continuously monitor and characterize performance of large scale wireless networks, such as city-wide mesh networks, unplanned deployments of WiFi hotspots, and cellular networks. Beyond our initial eorts in building and deploying this infrastructure, we have also utilized it to gain some initial understanding of the diversity of user experience in large-scale wireless networks, especially under various mobility scenarios. Since our vehicle-mounted testbed nodes have fairly deterministic mobility patterns, they provide us with much needed performance data on parameters such as RF coverage and available bandwidth, as well as quantify the impact of mobility on performance. We use our initial measurements from this testbed to showcase its ability to provide an ecient, low-cost, and robust method to monitor our target wireless networks. These initial measurements also highlight the challenges we face as we continue to expand this infrastructure. We discuss what these challenges are and how we intend to address them.
one possible solution:
Download the android SDK; write an app; run it in the emulator that comes with the SDK.
I'm not sure how much work it'd be to tie your 3G card(s) into the emulator (that comes with the SDK), but it's possible.
Linux would be my first choice, but the SDK also runs on windows or mac os.
Bonus for getting a useful app included in the app store.
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.
I was a 3G data engineer for Sprint PCS during the launch of 2.5G and 3G data. There are a few problems with the type of testing it sounds like you want to do.
First, I would suggest reading the specs from the IEEE on CDMA 2000, aka 3G. CDMA2000 allows the ability to allocate and de-allocate bandwidth on demand and based upon quality of service configurations. At night, with no one on the cell tower, you're going to get the full pipe for data. You'll see bursts up in speed but then several things can happen. First, voice takes priority. So at midnight in this scenario, I pick up my phone and make a voice call and I take priority. You're pipe just got smaller. The next variable is overall tower usage. Cellular towers shrink and expand RF power with regards to usage. As more users get on, the cell tower will reduce it's footprint. So even if hardly anyone is on the phone, but there are a ton of subsribers on a cell, it can drop it's power. So your bandwidth and RF are variables which change by the second.
So if you're just doing a "Hey lets just see what we see," type of test, then expect a huge array of data with not too many descernable results. If you're looking for data to be compared with something else (carrier vs carrier, region vs region), then it also won't be terribly useful. As a geek, it'll be cool to know you can set the test up, but as a quantitative analysis tool it won't be repeatable or statistically useful. You also can't really compare it to desktop loading times either. The images you "download" via a wireless carrier are not the same. Go to Yahoo and download the GIF for their logo using an aircard or wireless carrier device. Now, download the same with a desktop PC over a wired (or other non-wireless carrier method). Not the same file size, huh? :)
Just as an aside, I used to test it using Stick Figure Death Theater ( www.SFDT.com ) since you can start a really long download and watch the stats. Also, it was entertaining to watch at the same time.
Shameless self-promotion ahead...
This is more a suggestion to help with mapping received signal strength (RSSI), rather than data network latency and bandwidth (you can argue that those data network metrics rely heavily upon your RSSI!):
Grab an old Nokia, use gammu to enable Network Monitor mode, fire up a GPS and display the combined information streams on a map. I did exactly that as an experiment using a Nokia 3310 and a Navman GPS receiver. Interesting to then correlate the signal peaks to the actual base station locations.
The main caveat is that the old Nokias in question only do (I believe) dual-band 2G GSM at best, so you won't actually be able to measure 3G W-CDMA statistics as if you were connected with a 3G data device. I would offer, however, that 3G RSSI might be related to that of 2G as many of the base stations handle both services (ignoring differences in signal propagation characteristics). A starting point at least...
Those adapters require you to install software(ATT Connection manager in their case) that's only supported on Windows and Mac, and that software is required to "authenticate" your computer and use the network.
(Disclaimer - I work for Vodafone, albeit as a lawyer)
I have never tried with one of the PCMIA cards, but, most Huawei modems will work fine under Linux - you might need usb-modeswitch to flip it into modem mode (as opposed to mass storage mode), but, otherwise, it should not be a problem.
If using Network Manager (works automatically under Linux Mint 7 and 8), or tinkering with ppp (this was not difficult using Xandros on an Asus EEE 701), is not your thing, Vodafone has also released a version of the Vodafone Mobile Connect client for Linux, which should work with any provider's SIM. More details at Betavine. It's gui-driven, and should be usable by those without a particular interest in how/why things work.
We also do our best to support those in need of assistance, irrespective of provider, but, since it's just a few of the R&D team, and (very occasionally now) me, it really is a "best efforts" rather than a "guaranteed support" environment.
There are plenty of expensive software solutions for this that are used at a professional level (ROMES, NEMO TEMS etc).
If you are after a free solution, the AT commands of most units Huewai, Option etc will give you network information,
For example: Signal as RSSi. (look under 3GPP TS 27.007) AT+CSQ? gives a number 0 (-113dBm or Less) to 31 (-51dBm or greater)
Failing that a lot of the dashboards have open APIs (in the UK Vodafones dashboard gives you access to lots of information)
Most of the Samsung mobiles have a diagnostic screen giving levels Scrambe Code and Cell IDs
For more info Siroda.co.uk or pm me
Si