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The growing demand for mobile wireless access has stimulated the emergence of new communication technologies. Opportunistic Spectrum Access (OSA) is viewed as a promising alternative to overcome the problems caused by static spectrum assignment. Opportunistic access allows dynamic mapping of the transmission needs and communication opportunities. However, performing this task efficiently is not trivial. Indeed, it has been shown to be NP-complete. In this context, this paper presents an efficient heuristic for solving the channel allocation and data assignment problem, according to the opportunities and channels available. The proposed heuristic is optimal in terms of energy consumption, being close to the optimum, about 5% above, in terms of transmission time.

The growing demand for mobile wireless access has stimulated the emergence of new communication technologies. Opportunistic Spectrum Access (OSA) is viewed as a promising alternative to overcome the problems caused by static spectrum assignment. Opportunistic access allows dynamic mapping of the transmission needs and communication opportunities. However, performing this task efficiently is not trivial. Indeed, it has been shown to be NP-complete. In this context, this paper presents an efficient heuristic for solving the problem of channel allocation and routing, according to the opportunities and channels available. The proposed heuristic is optimal in terms of energy consumption, being close to the optimum, about 5% above, in terms of transmission time.

In wireless ad hoc networks, bridges and articulation nodes are critical elements that, in case of failure, render the network disconnected. Owing to their relevance, a number of works try to extend the life span of these elements. Nevertheless, in critical situations, such as the unavailability of a critical link, ways to reestablish the communication, even if for short periods of time, can be of importance in a number of urgent tasks. In this context, this work explores the concept of Cooperative Communication (CC) to monitor critical nodes and links and recover network connectivity in case of disruption. Unlike other works that perform exhaustive search to locate suitable CC-links that require global topology information, the proposed scheme identifies critical nodes and links based solely on local information. Compared to other prominent works, the proposed solution was able to reduce the computing cost to create CC-links in ≈ 67 times in the evaluated scenarios while persisting a lower message overhead.