Abstract
Designing routing protocols in Low power and Lossy Networks (LLNs) imposes great challenges. In emergency scenarios, the large and rapid data traffic caused by emergencies will lead to network congestion and bring about significant packet loss and delay. Routing protocol for LLNs (RPL) is the IETF standard for IPv6 routing in LLNs. The basic version of RPL uses Expected Transmission Count (ETX) as the default routing metric; it cannot solve the problem of sudden large data traffic. In this paper, we propose a congestion avoidance multipath routing protocol which uses composite routing metrics based on RPL, named CA-RPL. A routing metric for RPL that minimized the average delay towards the DAG root is proposed, and the weight of each path is computed by four metrics. The mechanism is explained and its performance is evaluated through simulation experiments based on Contiki. Simulation results show that the proposed CA-RPL reduces the average time delay by about 30% compared to original RPL when the interpacket interval is short and has almost 20% reduction in packet loss ratio. The CA-RPL can effectively alleviate the network congestion in the network with poor link quality and large data traffic and significantly improve the performance of LLNs.
Highlights
In recent years, various kinds of natural disasters and hazardous substances accidents have occurred repeatedly, causing great losses
The work in [11] introduces a study of Routing protocol for Low power and Lossy Network (LLN) (RPL) under the data collection model, compared with the Collection Tree Protocol (CTP), and the results show the advantages of RPL in terms of improving Packet Reception Ratio (PRR) and keeping low energy consumption
We propose a congestion avoidance multipath routing protocol which uses composite routing metrics based on RPL, named CA-RPL
Summary
Various kinds of natural disasters and hazardous substances accidents have occurred repeatedly, causing great losses. The ROLL working group has specified two kinds of Objective Function, one is the Objective Function Zero (OF0) [8], where the hop count is the only routing metric adopted, and the other is Minimum Rank with Hysteresis Objective Function (MRHOF) [9], where Expected Transmission Count (ETX) is the routing metric adopted These two OFs both take only a single metric as routing decision metric and perform poorly in LLNs, especially in emergency scenarios. The CA-RPL is suitable for LLNs in emergency scenarios, and it can effectively alleviate network congestion by dispersing a large amount of data traffic to different paths and reduce the packet delay.
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