A priority based algorithm for adaptive superframe adjustment and GTS allocation (PASAGA) in IEEE 802.15.4 LR-WAN

Internet of Things (IoT) is the trend of future Internet, and wireless sensor network (WSN) is one of the core components of the IoT. WSN consists of a number of devices which can communicate to each other, to transfer control and status data. These devices are used in the sensing layer of IoT, and IEEE 802.15.4 is one of the major standards used in WSN. IEEE 802.15.4 can optionally use the superframe structure to regulate the transmission of data. The superframe includes active portion and inactive portion, and the active portion can be divided into contention access period (CAP) and contention free period (CFP). The contention free period (CFP) is used for applications that need time-critical and QoS requirements. CFP consists of one or more guaranteed time slot (GTS), and data fragmentation problem occurs frequently if the GTS is divided inappropriate. Furthermore, the beacon order and superframe order cannot adaptive adjustment according to the traffic type and network condition, resulting in performance decrease. In order to solve the above problems, we propose a priority-based algorithm for adaptive superframe adjustment and GTS allocation (PASAGA) for the superframe structure. PASAGA improve the goodput and delay for high priority data by dividing the GTS length from historical packet size and adjusting BO and SO according to network load. Simulation results show that the proposed algorithm outperforms the IEEE 802.15.4 standard in terms of goodput, delay and energy consumption for high priority data.