In this paper, we present the review of energy harvesting contained in electromagnetic waves. An overview of existing energy harvesting techniques is discussed, which will motivate researchers to design antenna in the field of electromagnetic energy harvesting. It also focuses on a characteristic of patch antenna for designing Rectenna.
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 this paper, we discuss the basic responsibilities of MAC layer and its functionalities in cognitive radio sensor networks (CRSN). We mainly focus on investigating the MAC layer issues while realizing the cognitive capability into wireless sensor networks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.