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Observing my cellphone switch towers

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Re: Observing my cellphone switch towers

#71

Post by newhouseb »

drmpeg wrote: post #41
ng55QPSK wrote: post #2

"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

The srsLTE/srsRAN code is also fairly accessible and well written -- a year or so ago I used it as a reference for demodulating LTE downlink signals (in a python notebook).

Also worth calling out ShareTechnote which is basically the personal notebook of a (brilliantly prolific) telecom engineer (now at Apple): https://www.sharetechnote.com/. It's incredibly comprehensive and well linked -- a much easier reference than paging through hundreds of pages of PDFs.

Re: Observing my cellphone switch towers

#72

Post by lighttower »

How much does the positioning of the phone in the car affect it's antenna effectiveness and directionality. I'm astounded that you can "bury" the phone in a pit beside the gear shift with a pile of metal on top (the dashboard) and it still works.

The engineering me needs to place antennas optimally! Even though burying the phone in a pit and it still works it still irks me and I want to see it in an optimal placement where it is minimally shielded. Why don't car manufacturers have a place for the phone in the roof or something so that it gets optimal antenna placement? Yes it would be unseemly but wouldn't we get much better reception?

Re: Observing my cellphone switch towers

#73

Post by newhouseb »

Gys wrote: post #69
drmpeg wrote: post #41

Earlier quoted context omitted.

The most popular open source LTE stack is srsLTE (now called srsRAN). https://github.com/srsran/srsRAN

Unfortunately this refers to srs.io for more info, but that domain is not found. So I am left wondering what SRS means.

You want https://www.srsran.com/, but to save you a click: SRS stands for Software Radio Systems.

Re: Observing my cellphone switch towers

#74

Post by ng55QPSK »

rcarmo wrote: post #16

This 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…

There is no decision at the terminal side, there is no negotiation. Network collects reporting from the terminal(s) and decide centrally.

Re: Observing my cellphone switch towers

#75

Post by frombody »

lighttower wrote: post #72

How much does the positioning of the phone in the car affect it's antenna effectiveness and directionality. I'm astounded that you can "bury" the phone in a pit beside the gear shift with a pile of metal on top (the dashboard) and it still works. The engineering me needs to place antennas optimally! Even though burying the phone in a pit and it still works it still irks me and I want to see it in an optimal placement…

The better place to get reception would be through the charging or audio port.

It's an easy way to extend the phone antenna to the whole vehicle.

Re: Observing my cellphone switch towers

#77

Post by ectopod »

iudqnolq wrote: post #64
the8472 wrote: post #47

Earlier quoted context omitted.

the GPS location is reported by the tower, so nothing is stopping a mitm device from spoofing that too

Edit: totally wrong. Thanks ectopod8! I'm pretty sure gps location is derived from signals from GPS satellites and ground stations. You can see this if you're somewhere with no cell signal but have gps, or visa versa.

The GP is talking about the tower location, not your own location.

Re: Observing my cellphone switch towers

#78

Post by qorrect »

1f60c wrote: post #26
FreshFries wrote: post #23

Earlier quoted context omitted.

You probably mean Richard Vijgen's art project: http://www.architectureofradio.com The iOS application: https://apps.apple.com/us/app/architecture-of-radio/id103516...

Wow, HN rocks! That's exactly the app I was thinking about.

I remember this also, sadly it's more of an art project.

Re: Observing my cellphone switch towers

#79

Post by teeray »

Balantio wrote: post #3

How 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.

I think trains are kind of a special case in telephony when it comes to handoffs. It’s a unique situation where you have hundreds and hundreds of UEs[0] having to detach and re-attach, which makes for a very busy MME[1]. Sometimes those phones are only briefly connected to a given eNB[2] too, which makes all that effort for naught.

[0] Phones

[1] The system which sits immediately behind cell towers and coordinates handoffs

[2] Tower

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