  Disaster relief networks are designed to be adaptable and resilient so to
encompass the demands of the emergency service. Cognitive Radio enhanced ad-hoc
architecture has been put forward as a candidate to enable such networks.
Spectrum sensing, the cornerstone of the Cognitive Radio paradigm, has been the
focus of intensive research, from which the main conclusion was that its
performance can be greatly enhanced through the use of cooperative sensing
schemes. To apply the Cognitive Radio paradigm to Ad-hoc disaster relief
networks, the design of effective cooperative spectrum sensing schemes is
essential. In this paper we propose a cluster based orchestration cooperative
sensing scheme, which adapts to the cluster nodes surrounding radio environment
state as well as to the degree of correlation observed between those nodes. The
proposed scheme is given both in a centralized as well as in a decentralized
approach. In the centralized approach, the cluster head controls and adapts the
distribution of the cluster sensing nodes according to the monitored spectrum
state. While in the decentralized approach, each of the cluster nodes decides
which spectrum it should monitor, according to the past local sensing decisions
of the cluster nodes. The centralized and decentralized schemes can be combined
to achieve a more robust cooperative spectrum sensing scheme. The proposed
scheme performance is evaluated through a framework, which allows measuring the
accuracy of the spectrum sensing cooperative scheme by measuring the error in
the estimation of the monitored spectrum state. Through this evaluation it is
shown that the proposed scheme outperforms the case where the choice of which
spectrum to sense is done without using the knowledge obtained in previous
sensing iterations, i.e. a implementation of a blind Round Robin scheme.
