Sustaining Packet Delivery in Mobile RPL Networks: Radio-Only Objective Functions for Constrained Devices

Abstract

The IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) selects parents by reacting to transmission failures, so under mobility it loses packets before it adapts, and the remedies that anticipate degradation read node position, a sensor constrained devices do not carry. How far an objective function can go with the radio alone is what this paper asks. The same signal level, trend and staleness are read by two mechanisms, which share a parent-selection policy. Over cells whose boundaries are read from a Gaussian hidden Markov model fitted offline, the first applies a rule of fixed values. With a contextual bandit rewarded by per-neighbor transmission counters, the second estimates each cell value online. Both admit a variant that consumes frames decoded for other destinations, raising the sample rate without transmitting. In Cooja, over eight topologies and ten seeds, the bandit with hand-set boundaries and the added evidence raises mobile-node delivery from 17.6 % under the standard objective function, and 42.7 % under that function with the shared policy, to 78.6 %. That figure is above the strongest position-based baseline at under a third of its parent changes, with the margin holding under a paired test. With no more parent changes than the standard, the fitted rule reaches 62.2 %. Under the fitted rule, radio energy per delivered packet falls to a fifth of the standard’s, and under the bandit to a third or two fifths. Both rules fit a Z1 mote where the position-based baselines do not link, and the ordering survives a second medium with spatially correlated shadowing and per-pair line-of-sight states.