In emergency situations like an attack on a building, public networks are not sufficiently reliable. Hence field forces, who want to share multimedia mission information, have to build up their own multi-hop wireless network. To build up these ad hoc networks, battery driven wireless nodes with meshing capability, called dropped units, present a new technology option for homeland security applications. To ensure sufficient coverage, an excessive usage of dropped units seems to be an obvious solution, but leads to undesired effects, such as interference. To solve this dilemma, rules to find an optimal number of dropped units are presented in this paper. To derive guidelines for this, realistic homeland security scenarios were analyzed. A dedicated simulation environment provided a reliable prediction of the required number of dropped units. We analyzed the communication link of moving or movable wireless clients like surveillance and first responder's devices. The simulation results lead to the conclusion that with a limited number of dropped units a practically 100% network availability can be achieved.