الفهرس 
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Abstract
The high demand for wireless sensor networks (WSNs) is growing in
different applications. However, traditional resource-restricted WSN cannot meet such tremendous demands. Moreover, most WSNs use the unlicensed band (ISM band) which leads to congestion in that band. On the other hand, without damaging
the quality of service (QoS) of the network, minimizing the consumed energy is vital in sensor networks design.
Cognitive radio-based wireless sensor networks (CRWSNs) afford some solutions to the problem of scarce unlicensed band spectrum and a short lifetime network can mitigate WSN applications to rock unlicensed band. The sensing time is a crucial factor for the performance of spectrum sensing,and the optimum sensing time is a compromise between the performance of spectrum sensing and the secondary efficiency.This thesis assesses, a novel spectrum sensing scheme is proposed to maximize the accuracy of sensing as well as the energy efficiency of the
network by employing another adaptive spectrum sensing method according
to the first sensing result in order to provide better protection for the Primary User (PU). In other words, the Secondary User (SU) will perform spectrum
sensing again to confirm that the PU is indeed idle when the first sensing result indicates the PU is idle. Because of CRWSN sensor networks has a constraint
in energy, this adaptive sensing interval can also, be modified to optimize the
energy efficiency of the network according to the different activity of the PU.
Also, a wireless sensor network node uses a sequential two stages of
sensing techniques. the first stage is energy detection and the second stage is the maximum-minimum eigenvalue. it used to improve the probability of
detection which improves the throughput of the wireless sensor network node
Compared to other existing methods, simulation results were provided to
validate the efficacy of the proposed algorithms to enhance both spectrum
sensing performance and energy efficiency. The first proposed system has
achieved an enhancement in the detection process exceeds the ordinary
systems, and help in overcoming the noise un-certainty issue, but causes a
decrease in the throughput due to the double sensing process, compared to the
existing systems. Therefore, the second sequential system is used in order to
enhance the system throughput by decreasing the missed opportunists and use those times to transmit data and increase the system throughput.
Keywords: Wireless sensor network, Cognitive radio-based wireless sensor
network, spectrum sensing, sensing time, energy efficiency, sensing performance.