"There are no open source LTE stack to learn from" https://osmocom.org/projects
The most popular open source LTE stack is srsLTE (now called srsRAN). https://github.com/srsran/srsRAN
Observing my cellphone switch towers
41–50 of 137 posts
Re: Observing my cellphone switch towers
#42Re: Observing my cellphone switch towers
#43This is very interesting presentation. I wonder if the author considered researching the inter-eNB and backhaul latency and how it affected UE latency.
Re: Observing my cellphone switch towers
#44On a related note, this same mechanism can be used as a fallback for GPS to determine device location. I have worked on an IoT device with builtin SIM in the personal alarm space. Often when a device is indoors no GPS fix can be found, but the GSM module can report all celltower ids in range with signal strengths. These can be used to triangulate the device location. Google has an API for this where you can pass celt…
> I assume this is one of the many things Google is doing with their fleet of Streetview cars. ...and Google services-enabled Android smartphones. Source: I have used a single access points in many locations across the country in a relatively short period of time. When there's no GPS fix, Google always thinks I'm where I just was. (And there are no Streetview cars in some of these locations.)
Or your Wifi MAC gets tagged by a streetcar at one location, you move and google still things your at the old location. Had that, they even have way to feed that back iirc and was able to get that updated without a driveby of a streetcar. Note this was over ten years ago and WiFi density has increased.
Re: Observing my cellphone switch towers
#45Something like this would make it pretty easy to spot one of those stingray devices, I bet. Cell towers tend to stay put, so mapping out an area would go quick. Were a new 'tower' show up in an odd spot -- there may be shenanigans at hand.
Re: Observing my cellphone switch towers
#46How do i do this myself now? I always have put my phone in air plane mode when i was in a train due to the modem consuming a lot more energy. I always assumed and still doe its due switching towers and less connecitivy which means using more power. Whenever people argue that public transport doesn't need wifi i would argue against it due to power usage and also for more accessablity of the internet in general.
Something like Network Cell Info / Net Monitor / G-NetTrack on Android.
They actually show tower locations with signal strengths.
What I don't get is why the author didn't draw the signal strength of all towers that were visible. This info is also trivially available.
What public transport needs are microcells, and to hell with wifi.
Re: Observing my cellphone switch towers
#47Something like this would make it pretty easy to spot one of those stingray devices, I bet. Cell towers tend to stay put, so mapping out an area would go quick. Were a new 'tower' show up in an odd spot -- there may be shenanigans at hand.
the GPS location is reported by the tower, so nothing is stopping a mitm device from spoofing that too
Re: Observing my cellphone switch towers
#48This is so cool.
Re: Observing my cellphone switch towers
#49Earlier quoted context omitted.
s/LTE stack/mmWave stack ?
There are barely corporation-backed 5G mmWave stacks, and they're absurdly more complicated than 4G.
Can you shed more light on this? Do you mean in terms of beam forming? And other radio resource management complexities that arise from it?
I worked in 5G mmWave on the UE side so can imagine some of the scheduling complexity. However for a basic mmW stack, like one to be implemented by OAI or srsRAN would likely scale the problem down to something more basic
Re: Observing my cellphone switch towers
#50This is nicely done, and takes me back to when I worked in mobile network planning. Most people are blissfully unaware of how much radio chatter and constant adjustment is actually holding up their browsing session from second to second, with the UE negotiating the best possible terms (power, throughput, etc.) with adjacent cell towers before it decides (or is prompted) to hand-over to a new cell. Optimizing cell han…
Um, I'm pretty sure that there is not much of that handover stuff happening while browsing hacker news since that's likely in a low-velocity scenario, i.e., sitting on the toilet.
You would be surprised. If you're ever using your phone with a single available cell at low signal quality, just about anything will affect your signal... how you hold your phone, which room you're in, which way you're facing, etc.
The ability to switch to a different tower papers over all sorts of moment-to-moment connectivity issues.