Guaranteed Time Slot allocation for periodic messages with (m, k)-firm constraints in IEEE 802.15.4 networks

The IEEE 802.15.4 standard provides a flexible communication approach for LR-WPAN networks. When active, the beacon-enabled mode allows real-time communication by adopting a GTS (Guaranteed Time Slot) mechanism. However, this mechanism supports only up to seven real-time communicating devices. Motivated by this problem, this paper proposes the use of a dynamic GTS scheduling approach based on the (m, k)-firm task model, to deal with the GTS starvation problem. The proposed approach ensures that, for each admitted message stream S_i at least m messages will be transmitted within each window of k consecutive deadlines. The effectiveness of the proposed scheduling approach is demonstrated by a set of simulation and experimental results. The proposed approach is fully compatible with the IEEE 802.15.4 standard.