Advances in Cognitive Radio Sensor Networks
International Journal of Distributed Sensor Networks
Advances in wireless communication have changed the customs and the living style of people today, and the demand for wireless communication with high speeds and ubiquitous connectivity continues to increase. Currently a number of different wireless networks, for example, cellular networks and wireless local area networks, are in place to support mobile services but still new emerging applications require more support to meet communication requirements. Cognitive radio (CR) networks have emerged
... in response to the demand of these emerging applications as one form of several new wireless networks. A variety of new challenges and issues have also arisen with these new networking technologies, which have created many new research opportunities. While designing these emerging networks, it is not only important to realize innovative applications, but also crucial to investigate how to achieve the optimum bandwidth and energy efficiency, due to the scarcity of the network resources (bandwidth, channel, energy, storage, and so on). Such investigation requires a multidisciplinary effort that encompasses areas of signal processing, communication, control, and information theory. The major focus of this special issue is investigating how to achieve efficient use of spectral resources with low power consumption in the cognitive radio networks. Increasing demand for spectral resources has introduced the issue of efficient spectrum utilization. CR technology indeed allows opportunistic access to the spectrum. CR employs the concept of dynamic spectrum access (DSA) to improve spectrum utilization efficiency and communication quality. In addition to many other wireless systems taking advantage of DSA, several challenges and requirements of a wireless sensor network (WSN) can be met by using CR; therefore, some proposals suggested embedding CR within such networks. That gives rise to a new term, known as cognitive radio sensor network (CRSN). Despite the advantages offered by CRSN, embedding CR in sensors has also introduced several challenges. In addition to the challenges inherited from WSN, there are some unique challenges related to CRSN including definitions of channel, channel availability, channel heterogeneity channel quality, control channel assignment, and transmission channel assignment. This motivates the design of a new medium access mechanism for CRSN that can cope with all these challenges. Currently, WSNs have been used in a number of different applications ranging from surveillance and remote monitoring to healthcare; thereby, while designing protocol suite for CRSN, the underlying application also needs to be taken into consideration. CRSN mainly is composed of two parts: sensing and access policy. Briefly, sensing policy determines the set of channels to be sensed, the order in which the channels should be sensed, and duration of each sensing. After identifying the spectrum holes, access policy determines access related issues as to whether to access the band or not.