## 3 Proposed Scheduling Algorithm
### Estimating Amount of Packets in Queue
The proposed scheduling algorithm assigns time slots based on the priority, which gives the highest priority to the node with the highest QL. By assigning time slots based on the QL-based priority scheme, we can transmit packets to the sink node fast and reduce the number of packets buffered in each node while satisfying the end-to-end reliability requirement of IWSNs. Based on the simulation using Cooja, we have shown that the proposed algorithm guarantees the target end-to-end reliability required in IWSNs. The simulation results also showed that the proposed algorithm provides a much lower end-to-end delay of packets and lower queue level (number of buffered packets in the queue) compared with the flow-based approach [12]. This work was supported by the 2020 Research Fund of University of Ulsan. Not applicable. The authors declare no conflict of interest. ## References

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