In cognitive networks the service -at the lower physical radio- is provided by opportunistic use of bands of other networks than the basic one. This makes the QoS issue different from normal QoS issue in one to many networks in which there is a central control over the problem. Hence, for cognitive machine to machine communication, the two machines will have to negotiate their connection parameters over the cognitive radio band that probably belongs to a third party. Additionally, care should be taken not to harm the third part itself, especially if the cognitive radio used allows that the cognitive parties communicate on an active band of a third party which necessitates measures like communicating at much lower powers. Thanks. @AlDmour.

I'm thinking the two topics are orthogonal, perhaps. QoS techniques should be just as applicable to cognitive networks as they are to any network, as long as the opportunistic channel is available, of course.

 My opinion about QoS enhancement in cognitive networks is confiability and loss probabitity.