Reliability-Aware Packet Replication in Multi-Path Data Transmission for Mission-Critical IoT Networks

Mission-critical IoT applications require a strict reliability guarantee of at least 99% to ensure seamless operation. However, due to the resource-constrained nature of IoT networks, data transmissions inherently suffer from losses. This contradiction presents significant challenges for the traditional IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL), which was originally designed for general IoT networks. To address this issue, various multi-path RPL-based routing approaches have been proposed. One such solution is Reliable Multi-Path RPL (RMP-RPL), which attempts to enhance reliability by replicating packets and forwarding them through multiple parents. However, meeting the reliability requirement even with a multi-parent-based approach is difficult when the wireless links have high error rates. This is because one transmission attempt to each parent for a packet is not enough for such links. On the other hand, increasing the number of parents is also limited by many factors like resource consumption. To address these issues, we propose Reliability-Aware Packet Replication in Multi-Path Data Transmission (RAPID), which dynamically selects the number of parents and optimally determines the number of replicated packets per parent to meet the reliability constraint while minimizing redundant transmissions. The proposed scheme introduces a joint delivery ratio metric, and proposes greedy-based (RAPID-G) and approximation-based (RAPID-A) packet replication strategies to manage packet replication efficiently. Experimental results in Contiki COOJA simulator show that RAPID-A can achieve the reliability requirements of 90%, 95% and 99% under varying packet reception ratio and network density with an average energy consumption reduction of 34.23% as compared to RMP-RPL. The proposed protocol, RAPID-G, outperforms another multi-path algorithm, LFC, by 41.23%, 39.23% and 35.63% in terms of packet delivery ratio, end-to-end delay and energy consumption, respectively, and RAPID-A outperforms LFC by 38.63%, 44.12%, and 40.12% in terms of packet delivery ratio, end-to-end delay and energy consumption, respectively.