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A Class-Based EDF Scheduling for Bluetooth Piconet
Antoine Mercier, Pascale Minet and Laurent George

In this paper, we analyze Bluetooth ability to support Quality of Service (QoS) requirements defined by the application. In particular, we are interested in two QoS constraints : the importance degree of a message, and its delivery deadline. The QoS perceived by the application depends on the efficiency of the scheduling schemes chosen at the medium access layer. We show that One-Round Robin (1-RR) and Exhaustive-Round Robin (E-RR) do not provide a sufficient service differentiation. We then enhance 1-RR and E-RR with local class management and highlight the improvements on the average message response time and the percentage of messages missing their deadline for high priority classes. Finally, we define a new Bluetooth global scheduling, called Class-Based Earliest Deadline First (CB-EDF) that takes into account both locally and globally for these two QoS constraints. In our intensive performance evaluation, we consider various traffic configurations and different Segmentation and Reassembly (SAR) policies. CB-EDF simulation results are compared with those of FPQ that does not account for the importance degree of a message. Simulation results show that CB-EDF achieves a good service differentiation and allows the coexistence of messages with different application constraints on the same ACL link. Moreover, CB-EDF is a flexible solution that adapts itself to the knowledge level provided.

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