Interference avoidance in rapidly deployed wireless ad hoc incident area networks

In [1], we investigated the use of multi-hop relays (a.k.a. breadcrumbs) to extend the range of public safety communications in indoor environments where the radio propagation conditions are harsh or wireless communications are limited by distance. In this work, we consider the impact of interference on the reliability of the breadcrumb system. We develop a simulation model for the system that considers the incident area floor plan, the characteristics of radio propagation within the incident area, emergency responders' mobility, and the distributed functionalities of the breadcrumb system. We then evaluate the performance of the breadcrumb system in the presence of interference showing that it is diminished. Consequently, we consider the use of the cognitive radio technology to enable breadcrumbs to detect interference, to identify vacant channels, and to dynamically and autonomously adapt their channel selection to enhance the system performance. We develop the functionalities of cognitive radio in our simulation, re-evaluate the system performance in the presence of interference, and show that employing cognitive radios alleviates the impact of interference. We also highlight the overhead that the cognitive radio functionalities may have under favorable network conditions.