A Collision-Free Scheduling Algorithm with Minimum Data Redundancy Transmission for TSCH

The IEEE 802.15.4e specified the Time Slotted Channel Hopping (TSCH) that uses multi-channels and shared links to ensure a reliable and efficient data transmission in IoT applications. However, the standard does not define any scheduling mechanism for the network configuration. The main problem in TSCH is triggered when hidden nodes in a shared link transmit data at the same time. A collision happens even if the hidden nodes apply CSMA/CA before starting data transmission. To solve this problem, we propose Interference Collision Free Scheduling (ICFS), and Interference Collision Free Scheduling-Without Redundant Data (ICFS-WRD) algorithms to reduce the internal collisions caused by hidden nodes on shared links. The ICFS-WRD approach stands in contrast to proposals in the recent literature where shared links of the proposed TSCH schedules are free from colliding nodes. ICFS-WRD intentionally schedules the colliding nodes that sense redundant data on the same shared link, and let them alternate in transmitting data. This mechanism is targeted to sparse more cells for future flows, reduce the slot-frame size, increase the network’s lifetime and avoid transmitting redundant data. We propose a clustering technique to build a multi-hop cluster based convergecast traffic routing approach with a unique sink, on which we implement the scheduling algorithms. The proposed algorithms have been tested through simulations using network simulator NS3. The results show improvements in terms of energy consumption (ICFS saves approximately 23%), packets delivery ratio (ICFS achieves approximately 96.5%), and latency (ICFS-WRD delivers the packets twice faster than ICFS). We discuss some theorems and proofs that show that ICFS-WRD reduces the slot-frame size, increases the network lifetime, avoids transmitting redundant data, and minimizes the network’s congestion.