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UBC Theses and Dissertations

An adaptive scheduling algorithm for bluetooth ad-hoc networks Lee, Raymond Yan Lam


Bluetooth devices are required to form a piconet before exchanging data. Each piconet has a master unit that controls the channel access and frequency hopping sequence. Other nodes in the piconet are referred to as the slave units. In a piconet, the master controls the access of all devices to the channel through a time division duplex master-slave polling scheme. Several piconets can be interconnected via bridge nodes to create a scatternet. Bridge nodes are capable of time-sharing between multiple piconets, receiving packets from one piconet and forwarding them to another. A distributed scatternet scheduling algorithm is necessary: (i) to facilitate the polling operation from a master to its slaves; and (ii) to coordinate the switching of the bridge nodes between different piconets. In this thesis, we propose an Adaptive Scheduling Algorithm (ASA) for Bluetooth scatternets. ASA is adaptive in which the bandwidth allocated on each link or session is dynamically adjusted based on the estimated traffic. Moreover, ASA integrates both intrapiconet and inter-piconet scheduling to improve the aggregate throughput and delay. In addition, ASA prevents the bridge node conflict and satisfies the max-min fairness criterion. We compare our proposed ASA with two other scheduling algorithms via simulations. Results show that ASA can achieve the max-min fairness under different traffic conditions. Simulation results also show that under Constant Bit Rate (CBR) or bursty on-off User Datagram Protocol (UDP) traffic, ASA can maintain a high aggregate throughput and low delay. In addition, under Transmission Control Protocol (TCP) traffic, results show that ASA can achieve a small average transfer delay for different file sizes.

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