A Cognitive radio network (CRN) is formed by advanced radio devices, which observe the radio environment for a suitable band, employ an intelligent agent for decision-making, and a frequency-agile radio that can be tuned to a wide range of frequency bands and eventually A Spectrum-aware Clustering for Efficient Multimedia Routing in Cognitive Radio Sensor Networks operate on an intelligently selected band. Motivated by the spectrum utilization and regulation issue for exclusive use by the licensed or primary users, it brings a revolutionary change in this new paradigm by introducing a new class of unlicensed or secondary users who can share the spectrum opportunistically without interfering with the primary users. A Spectrum-aware Clustering for Efficient Multimedia Routing in Cognitive Radio Sensor Networks This new paradigm has also been investigated for wireless sensor networks (WSNs) to enjoy the potential benefits of cognitive radios, thus forming cognitive radio sensor networks (CRSN). CRSN can be utilized in many different application scenarios, for instance, intelligent transportation system , industrial monitoring, surveillance , smart grids , etc. Dynamic spectrum access plays a key role to mitigate the noisy spectrum bands and eases the reconfiguration of spectrum usage. Wireless multimedia A Spectrum-aware Clustering for Efficient Multimedia Routing in Cognitive Radio Sensor Networks sensors have been realized for monitoring and intelligent transportation in public transport vehicles, train. However, the spectrum utilization issues for multimedia delivery in vehicular networks have not been addressed adequately. The lack of established infrastructure, network dynamics, constrained spectrum access privileges along with the unpredictable band opportunity, and the nature of the wireless medium offer an unprecedented set of challenges in supporting demanding applications over CRSN. A Spectrum-aware Clustering for Efficient Multimedia Routing in Cognitive Radio Sensor Networks Thus, supporting multimedia applications of traditional WMSNs over CRSN presents many key issues, which are not dealt in its counterpart wireless multimedia sensor network. The varying capacity of wireless links in CRSN deteriorates the performance of a routing protocol in achieving end-to-end delay bound. The strict delay constraint is usually compensated by setting a suitable playout deadline to take into account the underlying network bottlenecks. Thus, by setting appropriate deadline in conjunction with playout time, the multimedia routing protocol should address the significant variation in delay and jitter to ensure the persistent quality of service for multimedia applications.