Combined sensing, performance and security trade-offs in cognitive radio networks

Cognitive radio networks (CRNs) enable secondary users (SU) to make use of licensed spectrum without interfering with the signal generated by primary users (PUs). To avoid such interference, the SU is required to sense the medium for a period of time and eventually use it only if the band is perceived to be idle. In this context, the encryption process is carried out for the SU requests prior to their transmission whilst the strength of the security in CRNs is directly proportional to the length of the encryption key. If a request of a PU on arrival finds an SU request being either encrypted or transmitted, then the SU is preempted from service. However, excessive sensing time for the detection of free spectrum by SUs as well as extended periods of the CRN being at an insecure state have an adverse impact on network performance. To this end, a generalized stochastic Petri net (GSPN) is proposed in order to investigate sensing vs. security vs. performance trade-offs, leading to an efficient use of the spectrum band. Typical numerical simulation experiments are carried out, based on the application of the Mobius Petri Net Package and associated interpretations are made.