Research On And Application Of Path Analysis Based Interference Localization In Mobile Communication Networks

With the rapid development of mobile communication networks,the radio propagation environment is becoming more and more sophisticated.The primary work in extra-network interference optimization is interference source localization.Because of multipath and non-line-of-sight propagation of interference signals in complex urban environments,the traditional geometric localization methods cannot meet the precision requirement.In actual network optimization work,in order to ensure the positioning accuracy,operating technicians have to positioning extra-network interference in a manual and step-by-step manner,which is very time-consuming and laborious.Therefore,there is an urgent need for more efficient and accurate technology for unknown extra-interference localization.Interference measurement data demonstrates the coverage distribution of interference signals emitting from interference sources,and is the basis for interference localization,while reverse ray tracing can effectively simulate signal propagation paths.To tackle the challenge of multipath and non-line-of-sight propagation of interference signals in complex urban environments,this thesis proposes a method of extra-network interference source localization by analyzing signal propagation paths,and this method consists of the following two parts:(?)Propagation Paths Generation.First,the interference measurement reports collected by driving tests are analyzed to generate the set of backtracking starting points,which are with strong receiving signal strength and located as scattered as possible in the area covered by the interference signal.And then,geographic scene modeling of the interference search area is conducted.With the help of the scenes,reverse ray tracing is used to generate the possible propagation paths of the interference signal by reversely tracking the signals from the starting points.(?)Interference localization based on signal propagation path analysis.At first,the interference search area is rasterized to transform the point localization problem into a three-dimensional grid one.Thhen,a 3D-DDA-like algorithm is taken to establish a relationship between the interference propagation paths and the grids,at which the interference source may be located.It is proposed that the grid where the interference source is located should satisfy multiple conditions,that is,it should cover as many strong signal propagation paths as possible from different backtracking starting points,and the propagation of different signals covered by it should meet the constraints of wireless signal propagation.Finally,a multi-objective optimization model is established for the proposed constraints,and the multi-objective optimization problem is solved by using scalarization basic theorem,while the result is the target grid where the interference is located.We integrated the mentioned-above method and developed a software for localizing unknown extra-network interference sources in mobile communication networks,and took it to identify extra-network interference in the practical LTE private wireless network for electric power systems in Nanjing,China.And it is shown that in a dense urban environment,the proposed localization method can achieve positioning accuracy with deviation within 60 meters.In summary,the interference localization method proposed in this thesis can quickly and accurately localize the location of extra-interference sources in the dense urban areas,and thus provides an efficient means to improve the efficiency of interference troubleshooting in mobile communication networks.