Interference Study Of The IMT System On The Beidou Satellite Navigation System

Nowadays,wireless communication system is entering a rapid development stage,especially the wireless data services.To meet the demand of current mobile internet development and the increasing high demand of mobile network services,the International Mobile Telecommunications system is developing fast by increasing the transmit power,deploying more service cellular,expanding the signal bandwidth.And what’s more,the members of IMT system are increasing such as 2G,3G,4G is already in use.The 5G system will join in the near future too.As a result,the composition of terrestrial communication system is becoming more and more complicated,consuming more frequency resources,transmitting stronger signal.But problems also arise.The fast development of IMT system may compete for frequency resources with other communication systems,and also my bring interference to other systems.As a very important navigation and location system,BeiDou(COMPASS)Navigation Satellite System is the foundation of national defense and national economy.The normal operating condition of BeiDou must be guaranteed.In response to the interference threat from IMT system,measures must be taken.Therefore,this article focuses on a series of problems about the interference between IMT system and BeiDou Navigation System:1)In this article we first establish a simulation scene for the interference problem of IMT system and BeiDou Navigation System.Then deterministic analysis and system level analysis are adopted to analyse the interference caused by downlink and uplink of IMT,obtaining the interference condition of BeiDou and nearby IMT system.2)A software is developed to analyse the interference between IMT system and satellite Navigation system.In this software,we include the deterministic analysis and system level analysis model.By using this software,we can analyse the interference caused by both the downlink and uplink of IMT system to the user equipment and ground control center.As different models are imported into this software,users also can define their own parameters to carry out analysis process.3)By analyse the interference between IMT and BeiDou,we find that the interference caused by the downlink is very serious.So,in this article,an algorithm(Interference Elimination Algorithm based on Subband Power Reallocation,(IEA-SPR))is proposed to deal with this particular problem.It is assumed that the COMPASS user equipment can transmit its own position and received interference power to the base stations of IMT system,then by using greedy strategy,the algorithm adjusts the transmit power of the subbands of IMT downlink dynamically until the received interference is under an acceptable level.By sacrificing some transmit power of IMT system to protect BeiDou Navigation Satellite System.Finally,a summarize of the research and achievement of this article is proposed,and some shortage and future research direction is pointed out.