A cognitive mechanism for vertical handover and traffic steering to handle unscheduled evacuations of the licensed shared access band

Abstract

There has been a steady growth in the traffic generated by Mobile Network Operators (MNOs), and by 2020 it is expected to overload the existing licensed spectrum capacity and lead to the problem of scarce resources. One method to deal with this traffic overload is to access unlicensed and shared spectrum bands using an opportunistic approach. The use of Licensed Shared Access (LSA) is a novel approach for spectrum sharing between the incumbent user (i.e., the current owner of the shared spectrum) and the LSA licensee (i.e., the temporary user of frequencies, such as an MNO). The LSA system allows the incumbent users to temporarily provide the LSA licensee with access to its spectrum resources. However, licensees must adopt vertical handover and traffic steering procedures to vacate their customers from the LSA band without causing interference, whenever this is required by the incumbent. These procedures should be carried out, de facto, before the base station is turned off as a part of a rapid release of unscheduled LSA band facing evacuation scenarios. Thus, in this dissertation, a cognitive mechanism is proposed to make decisions in advance to find the best target network(s) for evacuated customers in connected mode and with active traffic per class of service. On the basis of these decisions, the vertical handover and traffic steering procedures are carried out for the best target network(s), which are selected in advance and undertaken immediately to avoid interference between the licensee and incumbent services. Furthermore, this guarantees the seamless connectivity and QoS of evacuated customers and their traffic respectively, during and after the unscheduled evacuation scenarios. A performance evaluation conducted in a simulating scenario consisting of one LTE-LSA and three Wi-Fi networks, demonstrated that the proposed solution could be completed within the time required for the unscheduled evacuation, as well as, being able to ensure the QoS and seamless connectivity of the evacuees. The total execution time obtained during the performance evaluation of the proposed solution was around 46% faster than of two related works and could thus avoid interference between the licensee and incumbent services.