DREAD: distributed real-time air defense system

We present a solution to the problem of distributed air defense. The system consists of a set of 10 mobile nodes communicating with each other through a 500 KB/sec low bandwidth medium and via a surveillance satellite. These nodes are deployed on the battle-space and coordinate with each other in order to satisfy the system requirements. The system should be able to handle up to 10,000 tracks, identified as targets, and up to 100 tracks engaged by missiles. This involves analyzing tracks and determining whether they are targets, analyzing targets to determine their lethality and providing the signaling required for guidance. Thus, this real-time problem reduces to scheduling different types of real-time tasks before their respective deadlines. In addition, the number of tracks, targets or to-be-engaged tasks could temporarily exceed the capacity of a given node. Also, the different nodes must coordinate with each other to avoid redundant engagements and to ensure a consistent view of all tracks by the system. This not only entails scheduling the extra aperiodic real-time tasks needed to support the above activities, but also efficient location, transfer and information policies for load balancing and consensus protocols for ensuring a consistent view of all the tracks. The paper presents the system model in terms of the different modules and tables maintained to carry out the above functions. It describes the different design aspects considered, including scheduling, load balancing and consistency maintenance