Introducing QoS support in Bluetooth Piconetwith a Class-Based EDF Scheduling
Résumé
In this paper, we focus on the Bluetooth wireless network, analyzing its ability to support Quality of Service (QoS) requirements defined by the application. In particular, we are interested in two QoS parameters: (i) an application constraint denoting the importance degree of a message, and (ii) its delivery deadline. The QoS perceived by the application depends on the efficiency of the scheduling schemes chosen at the medium access layer. We define the minimal knowledge level required by a scheduling scheme to support these QoS constraints. As an example of classical scheduling schemes, we analyze performances of One-Round Robin (1-RR) and show that it does not provide a sufficient service differentiation. To achieve better service differentiation, we first present enhancements accounting locally for the two QoS parameters. These enhancements are applied to 1-RR scheduling scheme and we then give a comparison between the two versions. These comparisons are done by evaluating in each class, the average message response time and the percentage of messages missing their deadline. We then introduce enhancements in the intra-piconet scheduling. So, we define a new Bluetooth global scheduling, called Class-Based Earliest Deadline First (CB-EDF) that takes into account both locally and globally these two QoS parameters. 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 provided knowledge level.