S. Sengupta, M. Chatterjee, and K. Kwiat (USA)
Since static spectrum allocation has proved to be ineffective in maximizing spectrum utilization over time and space, dynamic spectrum access is clearly the best alternative for efficient usage of radio spectrum. In order to take advan tage of the flexibilities presented by dynamic spectrum ac cess, the newly proposed IEEE 802.22 standard based on cognitive radio is seen as one of the solutions that can har ness the unused or under-utilized spectrum. Also, the re cent success of wireless mesh networks is creating the pos sibility of availing wide-area wireless back-haul networks without the infrastructure cost that will have increased net work resource utilization and greater performance charac teristics at low cost. In this research, we study the current IEEE 802.22 system architecture and investigate the limitations in cre ating wireless back-haul mesh networks due to its lack of knowledge about the spectrum bands to be used. In this regard, we propose a coordinated distributed scheme for IEEE 802.22 enabled devices to establish a mesh network with reduced interference. The coordination is initiated by the base station and is followed by the iterative joining of the IEEE 802.22 consumer premise equipments to the mesh network in a distributed manner. We take a graph color ing approach and propose an algorithm called Maximum Utility Graph Coloring (MUGC) that allocates spectrum to the mesh network, enabling higher spectrum utilization and reduced collisions. We explore two objective functions: maximize utility and proportional fair utility to allocate spectrum efficiently. Through extensive simulation exper iments, we demonstrate how the proposed algorithm helps reduce collisions and most importantly, increase spectrum utilization among IEEE 802.22 devices.
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