In this phase, HIRO-NET deploys a robotic mesh network to bridge local disconnected meshes. Through the goTenna radios, drones and other robots have control links operating on VHF frequencies over ranges of 0.5-2 miles, thus maintaining inter-robot mesh connectivity. The robotic overlay network has Internet access, provided, in absence of cellular connectivity, through one or more satellite links established at rescue headquarters. HIRO-NET establishes at this stage a two-tier mesh network. The lower-tier consists of local mesh networks generated via short-range communications. The upper-tier uses goTenna to interconnect drones and other robots and connects isolated meshes to the global HIRO-NET network. It also carries dynamic control and coordination information among robots and first responders (e.g., discovered mesh networks, previously visited PoIs). If one or more survivors in the discovered meshes have Internet access (e.g., over online cellular, satellite or WiFi stations), the upper-tier is used to share access with all survivors in the lower-tier via routing algorithms.
As soon as disconnected mesh networks are discovered, HIRO-NET ground or water robots are automatically dispatched. Set theory is used to find the optimal deployment location at the intersection of network coverage areas. The specific robot to be deployed depends on the terrain of the path toward the optimal location. For instance, water robots would be deployed in a scenario similar to the aftermath of Hurricane Harvey, where large areas of Houston were flooded. Since smart devices are battery-operated, power consumption must be minimized. To address these challenges, HIRO-NET is designed to be energy-efficient and energy-aware, through load-balancing and routing policies that maximize network lifetime, performance and reliability.