Cellular Location Determination - Reliability and Trustworthiness of GSM Location Data

While using mobile telephony networks, the serving network infrastructure is able to determine the mobile station’s location. Until now, cellular telephony has been built on self-contained infrastructure, i.e. all network components have been certified and especially users have been unable to take over control over their mobile equipment’s behavior. With the rising awareness on privacy issues, software-based mobile phone network stacks became available and thereby a new freedom degree for mobile subscribers is introduced. While slight modification to the mobile phones behavior will not impair with the general functionality of the network, cellular location determination becomes less reliable and trustworthy. We discuss user imposed measures to detect external location determination attempts and to obfuscate generated location information. With a dedicated testbed setup, the effects of location obfuscation were evaluated.