Distributed decision making to improve link quality in coexisting TVWS secondary networks

In recent developments, regulatory bodies are introducing flexible use of spectrum such as allowing the use of temporarily unoccupied VHF and UHF bands also known as television white spaces (TVWS). The networks exploiting such opportunity, hereafter called opportunistic networks, have equal right to access available TVWS. As a result, unhealthy competition to occupy the same spectrum would be inevitable. Hence, coexistence becomes a critical issue to be addressed. We propose a distributed coexistence algorithm to be implemented by TVWS networks sharing a single TVWS channel. The TVWS networks cooperate by sharing operational parameters in order to implement self enforcing coexistence algorithms. Through the knowledge of the exchanged parameters, devices dynamically select the appropriate transmit power that minimizes the mutual interference among the cooperating networks. This increases the efficiency the available spectrum being used by the opportunistic networks and at the same time it fosters green communications by avoiding unnecessary wastage of power that builds interference between the resource competing networks. We demonstrate by simulation that choosing of optimum transmit power vector, in which each element of the vector corresponds to the optimum transmit power of particular network, ensures minimum outage occurrence that any of the cooperating networks experience link quality below a specified threshold.