Using UHF connectivity to off-load VHF messaging in tactical MANETs

Future mobile tactical networks are being developed to support an increased variety of data services (e.g. Blue Force Tracking, intelligence image or video reporting) in addition to the more traditional voice services. Such networks rely on an IP-based MANET stack, running over a UHF (Ultra-High Frequency) radio interface. Unlike legacy VHF (Very-High Frequency) radios, characterized by low bitrates but long-range coverage, the new UHF radios trade shorter transmission ranges for significantly higher bitrates. In particular UHF topology is subject to frequent splits and merges, resulting in intermittent UHF end-to-end connectivity. In this paper, we propose and evaluate a dual-radio broadcast message delivery mechanism. While the VHF radio guarantees eventual delivery, we show that exploiting intermittent UHF connectivity can greatly improve network performance. This is particularly true for delay-tolerant traffic.