The Design Of Passive Intermodulation Test System Applied In TD-LTE

As we all know, passive intermodulation is a significant factor in mobile communication system,which directly influences the quality of wireless communication system. Thus, the research of passiveintermodulation plays an important role in improving the quality of communication quality. With thepopularization of3G technology, the world is undertaking the exploration of4G technology. Thepaper designs a test system of passive intermodulation, which can be applied in TD-LTEcommunication system. At the same time, the test system has competitive price, simple operation andsuitable size.At first, the paper reviews the development of mobile communication technology, together withthe backgrounds and current situations. The paper analyzes the theories of passive intermodulation,the properities of intermodulation products, together with the influences to TD-LTE system, which laya stolid theory foundation for the whole system design. Then, the paper puts forward the overallsolution design according to the performance index and functional requirements. By extending thetesting methods recommended by IEC, the design realizes the analysis and design of passiveintermodulation products in TD-LTE communication system. After that, the paper introduces thehardware design and software design in detail. The hardware design includes the controlling module,signal transmitting module and signal receiving module. Among these modules, the main parts aredigital to analogue conversion and the design of signal sources. As for the software design, it consistsof overall design, drivers’ design, system parameter configuration and application design. The mostimportant parts are drivers for A/D conversation and several application designs.At last, the paper tests the passive intermodulation test system, including the tests of differentmodules and overall test. As a result, the system’s noise level can reach-140dBm and residual levelcan reach-137dBm, which satisfy all the designing requirements and the system proves to be accurateand reliable.