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IEEE 802.22 Wireless Regional Area Networks (WRAN) utilizes the Cognitive Radio dynamic spectrum access technique in TV bands. When allocating available spectrum to Secondary Users (SUs), in the absence of Primary Users (PUs), it is essential to ensure the Quality of Service (QoS) of SUs. The motivation behind this research is to devise a mechanism to ensure the QoS of SUs. The End to End delay (EED) experienced by SU through the devised mechanism need to be kept within the threshold suggested by WRAN standard. To achieve the above requirement, Dynamic Cooperative Spectrum Sensing (DCSS) is developed in this research. Two entities namely Spectrum Manager (SM) in Base Station (BS) and Spectrum Automation (SA) in SUs are engaged to realize them. They does the sensing of channel occupancy by the PUs. Further, a concept of Urgent Coexistence Situation (UCS) notification is issued by BS to indicate the re-arrival of PUs to SUs. Buffer mechanism is provisioned to restore the ongoing traffic of SUs until further resource allocation is accomplished. This strategy assures guaranteed data delivery of SUs traffic. However, this may introduce EED. Hence, this research investigates the performance of the developed DCSS mechanism in Netsim version 12 Simulator. The scenario with 1 Base Station, 3 PUs and 1 pair of SUs is constructed. Three different SUs traffic namely CBR, Voice and Video is considered. The impact of modulation schemes, occurrence of PUs traffic on average EED is analysed. From the simulation results, the modulation scheme that provides average EED within the threshold as per IEEE 802.22 is identified, thereby ensuring the QoS of the SUs. |
