Robust provisioning of multicast sessions in cognitive radio networks

Today´s wireless networks use fixed spectrum over long term and fixed geographical regions. However, spectrum utilization varies by time and location, which leads to temporal and special spectrum underutilization. Cognitive radio is an emerging technology that enables dynamic sharing of the spectrum in order to overcome the spectrum underutilization problem. In this paper, we consider the problem of supporting the multicast service mode in cognitive radio networks. Moreover, we are concerned with supporting this mode of service such that it is robust in the face of failures. We develop two algorithms which provide robust multicasting in such networks. Our proposed algorithms are: 1) multicast sessions protection with link-sharing trees and 2) multicast sessions protection using rings. These algorithms provision multiple multicast sessions, and protect them against a single primary user interruption at a time. They also take into account that the activities of a primary user may disrupt communication in several groups, of secondary users, which are referred to as Shared Primary User Risk Group (SPURG). The objective of the proposed algorithms is to increase the number of sessions that can be accommodated in the network and minimize the cost of provisioning the sessions while protecting them against failures.