Capacity Benefits of Airborne Nodes in Ad Hoc Networks with Broadcast Traffic

Tactical military networks are often ad hoc networks since it is a highly robust solution. The data rate in ground-based networks is often limited due to low antenna heights and a challenging wave propagation environment. In such networks it can be hard to achieve high enough data rate to support the requested services. A large portion of the traffic in tactical networks is broadcast or multicast traffic. Often, the used data rate is assumed to be the same for all links and tends to be low in order to reach all nodes in a network. A possible solution to improve the capacity is to add an airborne node to the network. In this paper, the performance of ground networks at 300 MHz is analyzed with and without an airborne node. The airborne node is positioned directly above and at a distance from the ground network. Also, both a detailed channel model including terrain data and a distance dependent channel model are considered. Results show the capacity improvement when adding an airborne node to an ad hoc network. Moreover, the use of a channel model with terrain considerations has a great impact on the results. For example, the required height of the airborne node, to achieve a certain capacity improvement, is severely underestimated when using the distance dependent model.