DRiPLOF: An RPL Extension for Multi-Interface Wireless Sensor Networks in Interference-Prone Environments

Abstract

The Routing Protocol for Low-power and Lossy Networks (RPL) is a popular routing layer protocol for multi-hop Wireless Sensor Networks (WSNs). However, typical RPL configurations are based on decade-old assumptions, leading to a mismatch with: (1) advances in wireless hardware; and (2) growing wireless contention. To soften the impact of external stressors (i.e., jamming and interference), we extended RPL to exploit the capabilities of modern multi-interfaced wireless devices. More specifically, our main contribution is the design, development, and evaluation of a novel RPL Objective Function (OF) which, through simulations, is compared to traditional single-interface approaches and a state-of-the-art multi-interface approach. We examine two scenarios, with and without the injection of jamming, respectively. Our proposed OF is shown to outperform, or otherwise perform similar to, all alternatives considered. In normal conditions, it auto-selects the best interface whilst incurring negligible protocol overhead. In our jamming simulations, it provides stable end-to-end delivery ratios exceeding 90%, whereas the closest alternative averages 65% and is considerably less stable. Given we have open-sourced our development codebase, our solution is an ideal candidate for adoption by RPL deployments that expect to suffer interference from competing technologies or are unable to select the best radio technology a priori.

Multi-Modal Industrial IoT Networks: Recent Advances and Future Challenges

“…A RPL Objective Function (OF) dictates how these sets are formed. Reprinted from [27] with permission from the authors and selecting a preferred parent (from the parent set), the RPL node computes the rank it will thereafter advertise (in DIOs) towards nodes that may then become its children.…”

“…Depending on the OF, rank computation may or may not be part of forming the parent set and selecting a preferred parent. For example, with Objective Function Zero (OF0) [30], for every candidate neighbor, a node first computes (see [27,Equation 1]) what its rank would be if it chose said neighbor as its preferred parent. It then keeps (in its parent set) the two nodes for which its rank would be lowest (provided they comply with universal rules).…”

“…With that in mind, Lemercier et al's [32,35] PO solution is straightforward. The authors defined (what they called) a hybrid OF, which we termed the PO OF (POOF) [27]. POOF is based on OF0 [30], the main difference being the addition of a metric normalization process.…”

“…Most recently, the authors of [27] proposed the Dual-Radio interface RPL Objective Function (DRiPLOF). DRiPLOF is a PO solution which, on the surface, resembles POOF.…”

“…Figure 8 illustrates how DRiPLOF forms/maintains a DODAG assuming the use of: (1) Expected number of Transmissions (ETX) [29,Section 4.3.2] as inferred metric; and (2) freshness probes [27,Appendix B] to keep inferred metrics updated. The root starts a DODAG by broadcasting DIOs across all interfaces.…”