DDAS: Distributed Delay Aware Scheduling for DSME based IoT Network Applications in Smart Cities

With a plethora of Internet of Things (IoT) applications for smart cities, encompassing and supporting several enabling technologies for real-time performance, an enormous amount of network packets faces the challenge of timely delivery. The IEEE 802.15.4 standard is one of the most popular and extensively adopted networking specifications for implementing different IoT applications and catering to several application-specific Quality of Service (QoS) requirements. Deterministic Synchronous Multi-channel Extension (DSME) is one of the Medium Access Control (MAC) protocols of IEEE 802.15.4 standard that facilitates stringent QoS through the allocation of DSME-Guaranteed Time Slots (GTSs) between a pair of devices. Interestingly, the standard does not define any mechanism for scheduling the DSME-GTSs, thereby opening several research opportunities. In this paper, we propose a Distributed Delay Aware Scheduling (DDAS) mechanism to increase the efficiency of the DSME MAC by using priority-based guaranteed time slots scheduling. DDAS assigns priority to the devices according to the criticality of time and number of associated devices, i.e., it identifies various flow deadlines and assigns GTS slots accordingly. The DDAS scheme aims to satisfy and adhere to various delay deadlines in the data flows of an IoT application. The proposed scheduling mechanism is shown to outperform other closely related schemes in terms of latency as well as energy consumption.