During a recent presentation in our Privacy Seminar I realised there are actually two types of location privacy. And both are relevant for location based services and when thinking about the risk of portable devices and the Internet of Things.

The first type requires that your (exact) location remains unknown. This is relevant for location based services that you need to sign in to, in order to use them. An example of this is a service that allows you to see if some of your friends are nearby. You want to hide your exact location from the location based service (but still allow your friends to find you exactly where you are). There are many techniques to achieve this for example by only providing a rough estimate of your exact location, while still obtaining relevant, location based, information.

The second type requires that you cannot be identified based on your location.
Your location at night reveals your home address and thus your identity. Your location between 9 to 5 reveals your work address, giving a good indication of your identity, especially when combined with a few other location data points.
(Similar techniques allowed the FBI to recover the identity of Broadwell.)
This is the type of location privacy that is relevant for location based services that you do not need to sign in to (but still may want to determine your identity anyway).

Both types are also relevant for the smart devices we carry around with us (smart phones, tablets, smart watches, braces, etc.), and that all are capable of determining our location. Some of them know who we are from the start. Others may learn over time, so to speak. And both types of privacy will become even more important in the Internet of Things.