  The application of Mission Critical Machine Type Communication (MC-MTC) in
wireless systems is currently a hot research topic. Wireless systems are
considered to provide numerous advantages over wired systems in e.g. industrial
applications such as closed loop control. However, due to the broadcast nature
of the wireless channel, such systems are prone to a wide range of cyber
attacks. These range from passive eavesdropping attacks to active attacks like
data manipulation or masquerade attacks. Therefore it is necessary to provide
reliable and efficient security mechanisms. Some of the most important security
issues in such a system are to ensure integrity as well as authenticity of
exchanged messages over the air between communicating devices. In the present
work, an approach on how to achieve this goal in MC-MTC systems based on
Physical Layer Security (PHYSEC) is presented. A new method that clusters
channel estimates of different transmitters based on a Gaussian Mixture Model
is applied for that purpose. Further, an experimental proof-of-concept
evaluation is given and we compare the performance of our approach with a mean
square error based detection method.
