An increasing number of applications require a specific level of QoS on the communication channel and at the same time the fulfilment of some security demands. An example is VoIP that might require at least 100 kbps bandwith, at most 200 msec delay, and encryption (and/or hiding) of the package stream. Furthermore for example at most 10% of data/packages can be allowed lost or vanished due to noise or DoS attack. In our project we are working on a software defined radio platform (GNU radio) for the reason that we want to look into how the flexibility of a software defined radio can help us in achieving specific QoS and security demands needed by typical applications. The setup is simple and consists of two computing devices connected to software defined radios. The devices are running applications that require package streams over the air. A third computing device connected to a third software defined radio is the adversary that can carry out any kind of attacks – especially it can carry out DoS attacks by generating noise.