Bluetooth tabanlı sensor ağları için enerji etkin scatternetlerin oluşturulması

ABSTRACTCONSTRUCTING ENERGY EFFICIENT BLUETOOTHSCATTERNETS FOR WIRELESS SENSORNETWORKSSain SaginbekovM.S. in Computer Engineering˙Supervisor: Assist. Prof. Dr. Ibrahim Kürpeoğluo gAugust, 2004The improvements in the area of wireless communication and micro-sensor tech-nology have made the deployment of thousands, even millions, of low cost andlow power sensor nodes in a region of interest a reality. After deploying sensornodes in a target region of interest, which can be inaccessible by people, peoplecan collect useful data from the region remotely. The sensor nodes use wirelesscommunication and can collaborate with each other. However, sensor nodes arebattery powered and therefore they have limited energy and lifetime. This makesenergy as the main resource problem in sensor networks. The design process forsensor networks has to consider energy constraints as the main factor to extendthe lifetime of the network.The wireless technology used for communication among sensor nodes can af-fect the lifetime of the network, since different technologies have different energyconsumption parameters. Bluetooth, being low power and low cost, is a goodcandidate for being the underlying wireless connectivity technology for sensornetworks tailored for various applications. But in order to build a large networkof Bluetooth-enabled sensor nodes, we have to first form a Bluetooth scatter-net. The topology of the Bluetooth scatternet affects the routing scheme to beused over that topology to collect and route informaton from sensor nodes to abase station. And routing scheme, in turn, affects how much energy is consumedduring transport of information. Therefore, it is important to build a Bluetoothscatternet wisely to reduce and balance the energy consumption, hence extendthe lifetime of a sensor network.In this thesis work, we propose a new Bluetooth scatternet formation algo-rithm to be used in Bluetooth-based sensor networks. Our algorithm is based oniiiivfirst computing a shortest path tree from the base station to all sensor nodes andthen solving the degree constraint problem so that the degree of each node in thenetwork is not greater than seven (a Bluetooth constraint). We also propose abalancing algorithm over the degree constrained tree to balance the energy con-sumption of the nodes that are closer to the base station. The closer nodes arethe nodes that will consume more energy in the network since all traffic has tobe forwarded over these nodes. Our simulation results show that our proposedalgorithm improves the lifetime of the network by trying to reduce the energyconsumed during data transfer and also by balancing the load among the nodes.Keywords: Wireless Sensor Networks, Bluetooth, Scatternet, Routing, ShortestPath Tree.