2024 年 32 巻 p. 319-330
RPL is a standard routing protocol for an IPv6-Based LLN (Low power and Lossy Network). In RPL, each node estimates link quality to neighboring nodes and selects its parent node by an OF (Objective Function) to construct a tree structure rooted at the sink node. Currently, a typical OF is MRHOF (Minimum Rank with Hysteresis OF). MRHOF on Contiki-NG, an operating system for LLN devices, adopts an active monitoring approach for link quality estimation, which consumes much battery power. This paper proposes BROF (Broadcast Reception based OF) based on a passive monitoring approach. BROF listens to control messages transmitted by neighboring nodes and exploits unicast messages transmitted to the parent node. The performance of BROF and MRHOF on Contiki-NG is evaluated with a simulator and a testbed. The evaluation results show that the delivery ratio and delay of data messages in both OFs are almost the same while the number of transmitted L2 frames for control messages in BROF is only 19.7% to 37.8% of that in MRHOF on Contiki-NG for constructing and maintaining a tree structure. This means that BROF can achieve almost the same performance for sensing data collection as MRHOF on Contiki-NG with remarkably less battery consumption.
