Routing Construction for Wi-SUN FAN Using ZDD-Based Graph Enumeration

The Wireless Smart Utility Network Field Area Network (Wi-SUN FAN) relies on IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) to construct large-scale multi-hop IP networks. However, local parent selection can concentrate traffic through a few relays, increase path depth, and amplify packet loss. We propose a centralized route-construction framework that aggregates neighbor reports at the border router and applies zero-suppressed decision diagram (ZDD) to enumerate all Destination-Oriented Directed Acyclic Graph (DODAG)-consistent spanning structures under global constraints such as hop bounds and per-parent child limits. From this feasible set, routes are chosen according to a network-wide objective and then minimized for total relay count. In a 75-router, 4 km × 4 km simulation with realistic Wi-SUN PHY/MAC and propagation settings, the selected routes improve end-to-end success rate and latency, achieving approximately 90% end-to-end packet delivery ratio (PDR) at low offered load. By optimizing globally before installation, our approach produces shallow DODAGs that reduce hop counts while balancing relay load, resulting in a substantial improvement in communication reliability.