Research On Co-existence Interference Between TD-LTE And LTE FDD Systems

As the mainstream technology of the mobile communication,LTE has been deployed in the global scope for commercial use.Nevertheless,the limitation and pressure of spectrum resource is growing.Thus,it becomes crucial that using the scarce spectrum resource in a reasonable planning and efficient way,to solve the issue about lack of the spectrum resource.Recently,reforming and reusing the band at 1800 MHz which used by 2G is the mainstream trend.However,TD-LTE and LTE FDD adjacent coexist in the band at 1800 MHz,and may be deployed in the same geographical region.On this occasion,it may not make certain that the two systems coexist by the 3GPP RF specifications.Hence,the issue,which about the co-existence interference to realize the compatible co-existence between the IMT systems,is needed.And the research findings can support the spectrum allocation,which is to achieve the higher spectrum utilizing efficiency and the reasonable co-existence deployment.The main research work is as follows:Considering the spectrum planning status in quo of IMT system in 1.8 GHz in our country,mainly study on the co-existence interference between the two LTE base stations.And analyse the influence of the factors to the co-existence interference,such as the protecting band,the configuration of the TD-LTE slot,the payload of the interference system,the bandwidth of the interference system and the MIMO system.The issue is studied with a method combining the link-level simulation and the deterministic analysis.The link-level simulation platform is built using System Vue.The simulation result of the system performance loss is showen under which set no more than 5% of the system throughput loss as the evaluation criterion of the acceptable external system interference.And then the isolation,which is needed to avoid the co-existence interference between the two systems,is obtained by the deterministic analysis.According to the result,it can't make certain that the two systems coexist by the 3GPP RF specifications.And the situation of LTE FDD interfering TD-LTE is more serious than the situation of TD-LTE interfering LTE FDD.Then it puts forward some suggestions to reduce the co-existence interference.In the actual project,setting 5 MHz protecting band between the two systems,and achieving a suitable isolation by adjusting the distance and direction angle of the two antennae,are both effective measures.Compared with the outfield test data of the State Radio Monitoring Center,the correctness of the analysis results are supported and demonstrated effectively.