A Cross-Layer, Mobility, and Congestion-Aware Routing Protocol for UAV Networks

Autonomous and decentralized unmanned aerial vehicle (UAV) networks are used in many applications, including disaster management, environment monitoring, and surveillance. The performance of the routing protocols in these networks drops significantly due to frequent route breaks and traffic congestion at high node speeds. This is partly because the routing metrics used in many of the existing protocols are sensitive to the intra-flow interference after the source node starts transmission on the selected route. Moreover, these schemes do not estimate potential packet drops or take preventive measures, such as route switching and queue management. To address these issues, we present a cross-layer, mobility, and congestion-aware optimized link state routing protocol for an autonomous and decentralized UAV network, which incorporates the following mechanisms: 1) Multimetric route selection which includes hop count, route lifetime, estimated time to destination, and number of interfering links; 2) preemptive route switching that prevents packet transmission over the broken and congested routes; and 3) queue management to prioritize transmission of packets based on their survivability score. We also present key observations on routing protocol design and a theoretical analysis to show the impact of data rate, route length, and interfering links on the packet service rate and congestion. The proposed routing scheme achieves a significantly higher packet delivery ratio and lower route computation overhead for delay-sensitive data flows at different data rates, node densities, and high speeds, as compared to the standard and multimetric OLSR protocols.