In recent years, there has been increasing interest in the US Department of Defense to build an on-demand airborne network for communications relay utilizing high-capacity, long-range military radio systems. While these systems operate well in a network of homogeneous systems, platforms generally employ multiple heterogeneous radio systems making internetworking difficult due to varying radio characteristics and lack of interoperability. Although simulations and emulation tests can provide a baseline for how systems will perform in a controlled environment, field tests are crucial to demonstrate capabilities in real-world operating environments. In this paper, we present measurement results from a field test involving two airborne platforms forming a dynamically routed aerial IP backbone over 200 nautical miles with various radio systems as part of the C4ISR on-the-move 2010 exercise. We present measurement results on per link performance, radio-to-router interface performance, and multihop network performance results with prototype software on open source platforms. Additionally, key lessons learned and recommendations are given.

The current generation of long-range, high capacity, military radios are stove-piped systems that work well in a homogeneous environment, but lack interoperability with other radio systems. Each radio provides a subset of disparate link information in non-standard interfaces and has built-in home-grown routers running different routing protocols. In a heterogeneous radio system airborne environment, wireless link characteristics change rapidly, often requiring direct link feedback from the radio to make routing decisions. In recent years, much work has been done in developing a common radio-to-router interface (R2RI) that standardizes a subset of per-link information to pass to the network layer for use in dynamic MANET routing. While simulations and emulation tests can provide a baseline for how systems might perform, field-tests are crucial to demonstrate capabilities in real-world operating environments. In this paper, we present measurement results from a field test involving several air and ground assets with various radio systems that test an implementation of RFC4938, a radio-to-router interface protocol, and its interaction with a dynamic MANET routing protocol. The assets formed a high capacity, dynamically routed aerial IP backbone made of heterogeneous radio technologies over 250 nautical miles (Nm), allowing the passing of military traffic.