End-to-end reliability- and delay-aware scheduling with slot sharing for wireless sensor networks

Applications that require the stringent reliability with delay constraint such as industrial process automation and patient monitoring have been emerged as new area of applications of wireless sensor networks (WSNs). This paper presents a per-flow reliability- and delay-aware scheduling algorithm for industrial WSNs. The proposed method adds time slots for retransmission to each link in order to satisfy required reliability. Furthermore, by sharing retransmission slots among different flows, the proposed method achieves the required reliability and forwarding delay while suppressing increase in the number of allocated slots. Through simulation-based evaluations, we show that the proposed method can reduce the number of slots allocated to neighbor links of a sink by up to 70% compared with conventional methods, which contributes to shorten the slotframe size, while satisfying the requirements of end-to-end reliability and forwarding delay.