Adaptive GTS allocation in IEEE 802.15.4 for real-time wireless sensor networks

The IEEE 802.15.4 standard is able to achieve low-power transmissions in low-rate and short-distance Wireless Personal Area Networks (WPANs). It supports a Guaranteed Time Slots (GTSs) allocation mechanism for time-critical and delay-sensitive data transmissions. However, the inflexible First-Come-First-Served (FCFS) GTS allocation policy and passive deallocation mechanism significantly impair network efficiency. This paper proposes an Adaptive and Real-Time GTS Allocation Scheme (ART-GAS) to provide differentiated services for devices with different priorities, which guarantees data transmissions for time-sensitive and high-traffic devices. The bandwidth utilization in IEEE 802.15.4-based PAN is thus improved. The proposed scheme is developed based on the IEEE 802.15.4 Medium Access Control (MAC) protocol and is fully compatible with the implementation of IEEE 802.15.4 devices. It is applicable to various real-time systems built upon wireless sensor networks. Simulation results demonstrate that our ART-GAS algorithm significantly outperforms the existing GTS mechanism specified in IEEE 802.15.4 in terms of success probability, average delay, average waiting time, and CFP bandwidth utilization.