How GPS became a human tracking mechanism

Hey guys - this is going to make a bunch of your apps work poorly or not at all, but it protects you from something you aren't informed enough or smart enough to be scared of in the first place. Please support me?

Oh, and by the way, it'll make your phone cost more money.

No. It's a futile effort. There's too much to know about too many things in this world, and of the important things that people should know, this is pretty low on the list. It's up to the professionals (ie. us) to make decisions on behalf of those who can't, don't, and won't be able to understand the ramifications of those decisions (be it because they don't have the time, capability, capacity, or willingness to understand).

It's the liberals standard reply: vote with your wallet. This way of thinking sometimes reduce democracy to economics.

Tracking people is a technological thing, but the power to do anything with that information is a legal and social thing.

The information's out there, and it'll never go away. What we need to do is work to steer the societal expectations that one's location is private, important, protected by law, not divulgable by the phone company except under penalty of law, not sellable for marketing purposes, etc.

This is a social problem. We fix it with laws.

Could you clarify what you mean by this? Positioning technologies in general are decentralized. You don't have to rely on the GPS L1 signal, most receivers support GLONASS, BeiDou, and Galileo outside of the box. You don't need to use WiFi positioning, Bluetooth ranging, or cellular positioning. These tools just give you finer granularity for your current position, minimizing Dilution of Precision.

While I'm honestly not that familiar with CGI-TA/UTDOA, the CGI is referring to the Cell Global Identity, which you can think of as a unique identity for every cell in existence (tower + direction + frequency IIRC). This might cover a very large area (a rural cell site might be 10+ km's away), or very small area (like an in building wireless system). The carrier tends to have a database of the location of each CGI, along with GPS coordinates of where the cell is located.

So, what happens, is by standard your CGI (or technology equivalent, because different technology use slightly different terminology), get's included in most messaging the cell network sends internally. While not perfect, this can be used to make guesses about your current location.

This is actually important for the cellular network, because if you have millions of devices, every message you send to the wrong location costs you money. So whenever your radio active (on a phone call, downloading a web page, your email in the background), all of the data for these services is sent to the cell servicing you. There isn't enough radio bandwidth to deliver this somewhere else or to a wide area.

It also get's used when you're radio inactive, to keep track of how to page you. Paging, is when the network needs to notify your UE (User Equipment), that it needs to do something (incoming call, sms, or data). Again, from an efficiency perspective, I don't want to page Vancouver when you're in Toronto.

So one of the way's the network does this, is even when you go radio idle, it remember's the cell you were last connected to. Because when the network wants to page you, it thinks the best location is the same location it saw you last. Now I don't remember UMTS as well as I should, but in LTE there are a few gotcha's. When the device is idle, it only needs to re-register every 1.5 hours, which means the device will also talk to the network every 1.5 hours to say, I'm still registered, don't clean up your resources, which will include the CGI. There is also a rule, that say's when you exit your tracking area list, you must notify the network to register with the new tracking area you can currently be paged at.

The Tracking Area, is a way to group cell's together into usually a relatively small area, but will be based on what the engineering group at your operator has decided. And you can have multiple of these assigned to the device. The idea basically is, you can make small movements around the network, but don't need to update the network for every cell change when idle. The network paging algorithm, will then page your last registered cell, followed by the tracking area list (and possibly some other heuristic features), to find your device and deliver your call.

From a privacy point of view, you can then imagine what this allows, was your phone near your girlfriends all night, or your own residence. However, if your local store is close enough, it might not be able to tell if you walked over to the corner store, especially if the CGI doesn't change (1.5 hour re-registration timer), someone might think you were just sitting at home if each registration is at the same location.

So, while this is all public standard, it's definitely difficult to articulate in terms, even technologists can follow, because cellular technology is it's own complicated piece of technology. This is why I believe it generally get's distilled down to the if you don't like it don't use it argument, because it's too difficult to articulate accurately, and in the end the cell network tracks the relative position of your phone in order to just service you as a customer. Even some of what I just said is likely slightly wrong / miss-leading / only applied to the network I worked on, as I haven't read all these standards recently.

And the CGI/TAI is generally the type of historical information that might be available from your operator, however, if you're the active target of an investigation, they can basically just ping (page) the device and wake it up to see where it is slightly more accurately. Unfortunately, I never got a chance to test whether the messages used by e911 GPS tracking gave a notification on the handset or not, but that's another way, at least in LTE, where you can ask the phone for it's current GPS coordinates.

I honestly don't know what the middle ground is, or how to have a truly informed public. I'm honestly not even sure how to have an informed discussion about this with technologists, as I think there is quite a lot of miss-information floating around. I suspect it's something easy to complain about, or make assumptions, like the cell network has perfect GPS style coordinates on every device every minute of every day, which is simply untrue. What it can be used for, is catching a criminal in a lie. I didn't even see my girlfriend that night, I was at home in bed. If a record say's otherwise, it can focus the investigation because the investigators found a discrepancy in the story.

Could this be used to catch a politician in a lie, or blackmail someone, I'm sure it certainly could. Does that actually happen, I have no idea, and I suspect if it does it's far more limited that most people would imagine. However, perhaps I have a poor imagination, but having worked many times with these records (including plotting), I highly suspect most people have nothing to worry about.

Are there exceptions, absolutely. So if your a criminal, I'd say don't use your phone to commit the crime, or if your worried that a state actor wants to track you down for something your working on, also, don't use your phone.

And just in closing, personally, I'm far more afraid of the carriers trying to make money off my data and personal information, and interfere with my service to achieve their profit margin, than I am of any state collecting my CGI and network signalling and being able to use that information in a meanginful way.

Assisted GPS is an "improvement" which depends on additional data from the cellular network. Which means the cellular network knows you are using it, knows where you are, and can track you.

Edit: Back in my Nokia days, I had phones with true GPS and 100% offline maps, which would work perfectly well for navigation far from any hint of connectivity. No idea whether Android's "Device only" mode is GPS or aGPS.