Abstract: Incorporating Cognitive Radio technology in Wireless Sensor Networks yields the Cognitive Radio Sensor Networks,which can reduce the interference of ISM band interference and improve data transfer rates. Cognitive Radio Sensor Networks have become a new hot research area. The concept of Cognitive Radio Sensor Networks was described. The research work on spectrum managemnet functionnalities such spectrum sensing, spectrum sharing, spectrum decision, spectrum mobility, and the network layer protocols, transport layer protocols, application layer protocols were introduced. The existing problems in the current researchwork and the new research issues were also discussed.

Key words: Wireless sensor network, Cognitive radio, Cognitive radio sensor network