earticle

영어

Recently, significant growth in the applications of the wireless sensor networks (WSNs) operating in unlicensed spectrum bands has been made. In the meantime, existing unlicensed bands are becoming congested and overcrowded. On the other hand, Cognitive Radio (CR) technology has been proposed as the key technology for future wireless communication that exploits dynamic spectrum access strategies. Since this offers more flexible way to utilize the wireless spectrum than traditional radio technology based on a fixed spectrum access policy, it is thought that the key feature of cognitive radio, i.e., dynamic spectrum access can be applied in WSNs to access the underutilized spectrum bands to transmit their readings in an opportunistic manner to the next hops and finally to the sink. In cognitive radio sensor networks (CRSNs), obtaining the information about spectrum holes on channel, negotiating among primary users and secondary users for spectrum allocation, synchronizing transmission parameters are the important functions of CR medium access control protocols. In this paper, we mainly focus on investigating the major issues to be considered with the existing communication protocols and algorithms devised while realizing the cognitive capability into wireless sensor networks. We also discuss the main challenges on the basis of dynamic spectrum management and extra energy expenditure to apply the cognitive capability into wireless sensor networks.