Research Of Radio Propagation Characteristics At Different Frequency And Spectrum Sharing In Cognitive Radio

Wireless communication is a research foucs in communication field today,the increasing wireless communications are carried on the limited spectrum resources.Since the propagation characteristics of the wireless signal on different frequency bands will present a greater difference,and smaller propagation losses let wireless networks cover broader area,so that low-band spectrum resources are more competitive.Cognitive radio(CR)allows non-authorized users use idle spectrum of licensed frequency,increase utilization of spectrum resources,and efficiently solve the issues of extreme shortage of spectrum resources.Participated in major national project of "TD-LTE network optimization tool R&D" and the project of "Broadband software defined radio platform development",the author has been engaged in research of wireless communicationsincluding radio propagation characteristics and spectrum sharing in cognitive radio,and in-depth study of indoor/outdoor radio propagation abilities on several key frequency bands and spectrum scarcity problems faced by wireless communications.The author has accomplished theory research,field testing and simulation analysis.The following are main contents:Firstly,the background and the meaning of this thesis were reviewed,and then major contents and organization structure of this thesis were introduced.Secondly,radio signal propagation mechanisms,propagation characteristics,wireless channel propagation characteristics and several general indoor/outdoor radio paropagation loss models were described in detail.Field testings of indoor/outdoor radio paropagation losses on several key frequency bands were carried,and then analyzed and verifed the differences of the propagation abilities.At last,the possible existence of "Room Gain" phenomenon was discussed.Thirdly,the new technology of spectrum sharing in cognitive raio was introduced in detail.The research mainly focused on the dynamic spectrum sharing technology based on game theory,and then simulated,analyzed and compared the performance of different game models for different senarios.In the end,the potential to improve spectrum utilization of spectrum sharing was expected.Shortcomings in the course of the study and corresponding improvements were proposed.