الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The rapid growth in the applications of wireless networks during the last decade has led to significant rising demand for the spectrum. Generally, the communication between nodes in the wireless sensor networks (WSNs) is done using the industrial, scientific
and medical (ISM) band, which is an unlicensed frequency band. On the other hand,
many other communication technologies share that band. Therefore, spectrum scarcity
is becoming one of the significant challenges for the WSNs. Nevertheless, large parts of the licensed spectrum have been found to be highly underutilized. In order to fix the
challenge of spectrum scarcity, the federal communications commission (FCC) approved the use of licensed frequency bands for systems, which use unlicensed frequency bands. Recently, cognitive radio (CR) is considered as a promising technology for wireless communication systems of the next generation. CR is able to identify the
unused spectrum within licensed and unlicensed spectrum band and allow the opportunistic use of the unused spectrum. The primary users (PU) are entitled to use the spectrum at any time, while secondary users (SUs) may use the spectrum only when the PUs
do not use it. This function of CR provides possible benefits to WSNs by enhancing the reliability of communication and increasing energy efficiency. Cognitive radio sensor
networks (CRSNs) may be deployed instead of WSNs for many applications. Examples of the potential areas that CRSNs can be deployed as follows: medicine and health, object tracking, logistics, facility management, precision agriculture, machine surveillance and preventive maintenance, intelligent roadside, monitoring of indoor and outdoor environments, security and finally actuation and maintenance of complex systems. Avoiding the interference with the PUs to protect the right of the PUs is considered as the main attention in CRSNs. CR wireless sensors are considered as a power constraint device within a limited energy source. In this thesis, a scheme is proposed to construct an energy-efficient clustering for
CRSNs through saving the communication energy between nodes into the cluster, in addition to the communication energy between cluster head (CH) nodes to the base station (BS). To corroborate the proposed scheme, extensive simulations in MATLAB
were carried out and the results of the simulation showed the superiority of the proposed technique over other algorithms in terms of the network lifetime.