Distributed Detection in OFDM Based Ad Hoc Overlay Systems

Overlay systems are a feasible approach to increase the efficiency of spectrum use. An independent secondary user (SU) system operates in the same frequency band as a primary user (PU) system. In order to avoid mutual interference, an important task of every SU system is to periodically monitor the PU system´s allocation. In this paper, we investigate the question how many SUs have to be deployed in the system area of an ad hoc network in order to meet a given network wide detection probability and how this effects the false alarm probability (and thus the performance of the SU system). This is achieved with the help of geometric random graph theory and results from a distributed detection approach. In our investigations we consider a scenario with an infinite system area, and therefore neglecting border effects, as well as a scenario including border effects.