Research On Hierarchical Architecture And Network Optimization Of IP Aeronautical Telecommunications Network

In recent years, China has continued to open up low-altitude airspace,which brings a new wave of industry to the general aviation market. To meet the greater network transmission needs of air traffic flow management, aircraft security and intelligent aviation system, the rapid deployment of aeronautical telecommunications network becomes an urgent research topic.Although the development and change of traditional aeronautical telecommunications network (from OSI to IPS) is an inevitable trend,there are still many problems to be solved in practical applications. The TD-LTE based broadband data link can support more extensive space-ground communication services, which solves the problem of low-altitude airspace safety monitoring and other issues. The technology also provides an alternative to IP aeronautical telecommunications network (IP ATN) construction.Taking the IP ATN as the main research object,this thesis analyses the feasibility of constructing IP ATN based on the TD-LTE, and researches the key technologies for IP ATN. It focuses on the architecture of TD-LTE based IP ATN, the mobility management scheme, Doppler frequency offset correction, and TD-LTE based IP ATN optimization. The contribution of this thesis includes:1) According to the demand of low altitude supervision service, a hierarchical architecture of TD-LTE based low altitude IP ATN is proposed.Considering the difference between TD-LTE and traditional ATN,this paper presents a hierarchical architecture for IP ATN. The transverse plane is divided into two sub-planes and the vertical plane is divided into three sub-planes. The design of network elements for IP ATN is also proposed. The proposed method addresses the problems of IP-based bearer, service integration, secure access and other issues. In addition ,this thesis proposes an E-GW based method to introduce the TD-LTE access network and the TD-LTE backhaul network into the IP ATN.2) To reduce the impact of the Doppler shift to the space-ground communications, a network optimization solution based on the base station side frequency offset estimation and compensation is proposed.To solve the Doppler frequency offset issue and utilize the advantages of single and double pilots, the thesis puts forward a method with the combination of single and double pilots. A modified frequency offset compensation scheme is also presented. The proposed method can reduce the impact of frequency deviation with low complexity and it is also verified through experimental demonstrations.3) In order to ensure the continuous space-ground communication in the process of low altitude aircraft moving, a method for optimizing the low altitude communication networks is proposed.For the limitation of the same-frequency network scenario between space-ground station and ground station, a networking scheme is proposed for different-frequency networking. The frequency selection and coverage recommendations are given under the different-frequency networking. And the different-frequency networking coverage recommendations are also given based on the analysis of the overlap region of low altitude coverage. Then the simulation analysis of coverage intensity and signal to noise ratio is carried out under the different-frequency network planning. The feasibility and rationality of the ground equipment coverage and network planning are certified by using the different-frequency networking according to the analyses results.