In todays world, smartphones are a constant and almost indispensable companion in day-to-day life. A study from Eurostat shows that 74\% of Austrian individuals aged 16 to 74 use Internet over mobile phones. Therefore, it is important to know why and how modern devices can effect the personal privacy through wireless emissions. Especially if the mobile phone is not connected to an Access Point and Wi-Fi is turned on. There can be wireless emissions because of a regular occurring network discovery to detect nearby Access Points. In this master thesis an extensive data collection of Wi-Fi frames is created and analyzed. The evaluation of the collected data led to the result that capturing of Probe Requests which are used for network discovery can be misused to provide a feasible and cheap tracking solution. Even if MAC randomization is used, devices could be tracked for multiple days. Also a combination of randomized MAC addresses which use directed Probe Requests was recorded. Directed Probe Requests can render MAC randomization completely useless.