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CreditsLast Updated 2014-03
This is an activity that illustrates how mobile devices communicate with mobile networks, highlighting how locations of mobile devices are triangulated as part of routine communication with these networks.This leads into a discussion that will get participants thinking critically about the implications of the geolocation and tracking capabilities of mobile devices.
Projector and images of mobile network towers - this site has a good range that are included below.
Ask if anyone has seen and can describe what a mobile network tower looks like. Expand from their answer to describe (and optionally show) that what we commonly call “towers” can indeed look like towers (example image), but can also involve different types of hardware. This system of hardware works together to provide the service we think of when we say our mobile devices communicate with the network via “towers.”
The hardware of mobile network “towers” that our devices communicate with can present as panels, antennas and small dishes on buildings and other structures, especially in urban environments (example images here, here, and here).
Some of them are only pointed in one direction, and others can receive and send signals 360 degrees. Mention that you’ll be calling them “towers” for the sake of simplicity, but you wanted to explain that they are made of different types of hardware and may not look like towers.
Ask for one volunteer to be your mobile phone moving through the mobile network. Then ask for three more volunteers to be “cell phone towers,” and ask them to stand at different points around the cell phone, with some being closer and others farther away.
Remind the group that coast-to-coast or otherwise long-distance calls via land lines in large countries used to take several minutes to set up, with the assistance of operators; people would make the request to the operator on the phone, and then wait quite a while for the call to be “put through” before they finally got through to the number they’d requested.
Describe to the group how we can sometimes take this comparatively immediate access and service for granted, and the recent growing awareness that mobile network providers can also see a LOT of information about us via our cell phones makes many people nervous.
We need to remember the reason why mobile network operators can do this: it’s because the network needs to constantly be in communication with our mobile devices. This is in order to know where we are in order to direct calls and text messages intended for us, to us as quickly and as efficiency as possible.
Ask: Why would that then keep track of that information?
Answer: So they can bill us!
Explain that is a very simplified version of how our devices “talk” to the mobile network, but the principle is the same.
Have participants run through this more than once if necessary, to ensure that the purpose and setup is clear to everyone.
In this step, you’ll simulate this process with the group in the context of a variety of locations and scenarios, where mobiles are interacting with the network in different ways.
Now have more towers come stand near by the first cluster of towers - approximately half to two-thirds of the participants if you can.
Congratulate them on helping the cell phone participant stay in touch with their network, while also “triangulating” their approximate location for the network, which lets them know (and log) approximately where the cell phone is, even if the phone does not have GPS.
Now ask the entire group to think of a time when they’ve experienced a strong signal (or full “bars”) and then a weak signal (low “bars”) for their mobile devices.
Explain that the demonstration they just saw was more akin to a denser, more urban environment, but now we’re going to demonstrate what the rural experience would look like as well.
Tell participants that the previous setup was an example of an “urban” environment, but we also experience rural environments, where towers are typically farther apart and provide “weaker” service.
To close, mention to participants that mobile phones ask a more complex digital version of “Where am I?” to the networks around them approximately every three seconds. That’s a lot of communication with the local network!
The closing of the activity should lead cleanly into the discussion - here are some questions to pose to the participants, to get a sense of how well the basic process of mobile phone functionality was understood:
What about fewer towers? (Answer: Yes - explain that with more “towers” in contact with the mobile phone, they have even more accuracy to pinpoint its location, which becomes even more detailed if the towers are closer to the phone, which is typically in urban environments).