| Mobile communication technology has evolved from the 2th generation(2G)mobile communication to the 4th generation(4G)mobile communication,which is developing towards high speed,low latency and broadband.At present,there are more than ten network standards in the domestic mobile communication network.However,the frequency used for mobile communication is mainly concentrated in 800 MHz to 2700 MHz.In the era of 2/3G,The frequency resource allocation has considered the interference of adjacent frequency systems due to fewer network standards and narrower carrier bandwidth.Therefore,there is a certain of frequency isolation in the different network standards of the domestic operators.However,in the LTE era,the phenomenon of serious shortage of mobile communication spectrum resource has become increasingly prominent because LTE carrier bandwidth can be configured up to 20 MHz.In order to make full use of spectrum resource,the phenomenon of adjacent frequency appeared between LTE systems and other systems.In the indoor distribution system,Remote Radio Unit(RRU)sends the signals of various network standards by means of combiner equipments,and then the signals are transmitted to different areas of the indoor through a shared antenna system.However,adjacent frequency systems will interfere with each other.Therefore,it is important to solve the interference problem of adjacent frequency systems.This topic is based on the research project of China United Network Telecommunications Corporation Limited Guangdong Branch,named research and application of spectrum utilization efficiently,radiation and interference control technology in multi-network coexistence.There are usually two methods for inter-system interference control: frequency isolation and space isolation,but there is neither frequency isolation nor space isolation in multi-network coexistence scenario.In this thesis,we propose a kind of combination technique in adjacent frequency systems for the scenario,and realize combination of adjacent frequency systems in minimum isolation bandwidth.The contribution of this thesis is in the following three aspects: Firstly,we reduce the minimum isolation requirement between the adjacent frequency systems.Then,we reduce the filter edge insert loss and redefining the segmented filter insert loss.Finally,we make full use of the non-actual transmission bandwidth(e.g.guard band)of the broadband mobile communication system to design minimum isolation bandwidth.This thesis has achieved no additional isolation bandwidth combination of adjacent frequency systems by means of above three methods,and has develops a series of adjacent frequency combiners which meet the mobile communication network application needs.In the development process,first of all,we use software simulation to provide theoretical basis and obtain preliminarily the key performance indicators of adjacent frequency combiner.Then,in order to verify the isolation requirements of the adjacent frequency combiner,the vital radio frequency indicators(e.g.EVM,ACLR,SEM,SWR,sensitivity)are tested under the different isolation in laboratory simulation networking environment and whether the radio frequency indicators meet 3GPP specification.Thus,we can determine isolation indicator of adjacent frequency combiner.Finally,the samples of adjacent frequency combiner are tested in the laboratory and in the actual network.In this thesis,the combination technology of adjacent frequency systems in mobile broadband communication system not only solves the problem between adjacent frequency systems but also possesses obvious advantages compared to 3d B bridge and 5MHz isolation bandwidth combiner.The adjacent frequency combiners increase the signal coverage compared 3d B bridge and improve spectrum resource utilization compared to the 5MHz isolation bandwidth combiner. |
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