الفهرس 
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Abstract
Due to the rapid and high-speed advancements in wireless technology, the spectrum supplier has become rare, expensive and heavily crowded. The proposed cognitive radio networks (CRNs) represent a promising technology for solving the problem of radio spectrum deficiency and to utilize this precious scarce resource effectively. Users in radio networks are divided into two types : the primary user (PU), the user authorized to use the frequency spectrum at any time, the secondary user (SU) who can use the spectrum but only in the time available without interference with PU. In traditional wireless networks, the nodes are connected based on a centralized infrastructure. But in Cognitive Radio Ad Hoc Network (CRAHN) Networks, mobile SUs nodes are connected to each other without a central infrastructure, Routing in CRAHNs is an important and necessary process and faces many and varied challenges. These challenges include PUs intervention, frequently dynamic topology, energy consumption problems, unavailable channels, and fragile connections between nodes. Due to all these previous challenges, the performance of the network is severely affected. In this thesis, we develop an enhanced multi-hop multichannel tree routing protocol (EMM-TRP) for cognitive radio network and we contribute the following: firstly, we proposed an EMM-TRP that jointly utilizes the tree routing algorithm with a spectrum management module in routing decisions. Secondly, we also proposed a new metric to find the best route, the main motivation in the design of this metric is safeguarding the PUs traffic from CR node interference and quick data transmission. Third, we have improved the EMM-TRP routing tree algorithm search by adding neighbors’ table technology. Finally, we offered recovery and discovery unit in the case of link failure. We carried out our experimental evaluations in ns2 simulator, it has been shown that EMM-TRP protocol achieves better performance in terms of average throughput, end-to-end delay, and overhead and hops count compared by SAMER, CRP, STOD-RP and CTBR routing protocols. Moreover, in this thesis, we expanded our study and analyzed the effect of PU nodes activity patterns on different routing protocols by simulating based on NS-2. We observed that Sporadic PU activity is the case where a robust routing protocol need to adapt and converged. In this case, also, the EMM-TRP is outperformed the other protocols.