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The current spectrum allocation model aims to avoid interferences in licensed spectrum communications without further concerns regarding spectrum usage. Because the radio spectrum is a finite resource, several approaches have been presented in order to improve the effectiveness of its utilization. The main contribution of this work is to present an opportunistic approach to spectrum sensing and allocation. Compared to other alternatives, our approach presents significant improvements in the spectrum access and utilization, improving network throughput up to 16 times.

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Cooperative communication (CC) is a technique that has been explored as an alternative to connect isolated network components in wireless ad hoc settings. However, existing solutions are centralized and have high computational cost, as they require complete topology information. This paper presents a distributed solution to improve network connectivity by exploring CC using localized information. Simulation results show that the proposed scheme is able to restore connectivity in more than 95% of the evaluated cases. Furthermore, transmission power needed to establish the CC is comparable to the cost of similar solutions that require global topological information.