Special applications and spectrum sharing with LSA

The commercial long-term evolution (LTE) networks of today offer fast and regionally wide access to the Internet and to the commercial applications and services at a reasonable price. At the same time, public safety (PS) users are still communicating with old-fashioned, second-generation voice and data services. Recently, the commercial LTE networks have been standardized to offer capabilities to mission-critical users. However, the commercial networks do not yet fully support the coverage requirements of the PS users. Moreover, the commercial infrastructure might be out of order in critical scenarios where PS actors are needed. Thus, the PS users require, for example, rapidly deployed LTE networks to support their own communication. This thesis studies the PS use of commercial operators' LTE networks and rapidly deployed closed LTE networks. The key tasks are to find out how to connect users seamlessly together between the different networks as well as finding out how the frequency planning is implemented. This thesis provides practical design solutions to guarantee network interoperability by connecting the networks as well as radio spectrum utilization solutions by licensed shared access (LSA). While the concept of LSA has been well developed, it has not been thoroughly investigated from the point of view of the PS actors, who have special requirements and should benefit from the concept. Herein, the alternatives for spectrum sharing between PS and commercial systems are discussed. Moreover, the thesis develops a specific LSA spectrum sharing system for the PS actors deploying their own network in scenarios where the commercial networks are insufficient. The solution is a robust LSA-based spectrum sharing mechanism. Note that PS actors also need to be able to utilize the spectrum when the LSA system is not available and when the commercial system has failed. Thus, this thesis proceeds on developing sensing methods for complementing LSA, where the sensing methods guarantee spectrum information for a rapidly deployed PS network. It is shown how PS actors can utilize available spectrum with a secondary spectrum licence. This is a good alternative to reserving the spectrum completely. The work assembles missing pieces of existing methods to ensure the functionality of the commercial and of the supporting rapidly deployed networks, both in terms of spectrum usage and application services.