Research On Test Method Of Rf Devices Performance In CDMA System:WCDMA Signal Generation And Analysis

Mainstream wireless communication systems are mainly composed of many large and small semiconductors which are componented by many RF power amplifiers and other RF devices.The performance of these RF devices affects the performance of the entire communication device deeply.So,testing the performance of mobile communication systems is mainly to test the performance of its internal analog devices.In the traditional method,the performance test of the RF device is generally obtained by testing multiple indicators of the device,and comprehensively evaluating the obtained multiple indicators,then judging the performance of the device by the comprehensive evaluation result.The entire process requires one-to-one testing of multiple parameter characteristics of the device.In this way,the testing process cumbersome and requires a variety of expensive testing equipment,resulting in a waste of human and financial resources.Based on this phenomenon,this thesis proposes a new test method to test the performance of RF devices in communication equipment under CDMA protocol.In the test process,firstly,it is necessary to generate a standard baseband signal as the system input signal.After the input signal passes through the device,an output signal is obtained,and the constellation diagram of the output signal is extracted,and finally the device performance is judged according to the characteristics of the constellation,which improve the efficiency greatly.Based on the above,this thesis first detailed descripts the framework of the new test system,and then introduces the 3GPP protocols that need to be followed to generate the system input signals.In the following,the key technical problems of inter-symbol interference encountered in standard baseband signal generation process are discussed in depth,and the raised cosine roll-off filter used to reduce inter-symbol interference is studied.Compared to the number of multipliers used in the design process,this thesis proposes a method to design a raised cosine roll-off filter using less multipliers.At present,the implementation of digital filters is usually based on sequence convolution,which often involves a large number of multiplication operations.However,in a digital system,lots of multipliers consume more resources and increases costs.In this context,this thesis proposes a novel method which bases on differential-accumulated structure.Applying this method to the raised cosine rolloff filter can effectively improve the resource utilization of the communication system.In the physical channel of WCDMA,the downlink DPCH(Dedicated Physical channel)and the downlink S-CCPCH(Subsidiary Common Control Physical Channel)channel are two representative channels.In this thesis,the downlink DPCH channel,the downlink S-CCPCH channel,and the downlink composite multichannel I channel are implemented.Q channel signal simulation.On this basis,the following DPCH channel is used as an example to simulate different RF devices under the new test system.The standard downlink DPCH baseband signal passes through the device under test to obtain the constellation of the output signal,which is treated according to the indicator parameters reflected by the constellation diagram.In practice,due to the needs of the project,the problems studied in this topic cannot stop at the simulation stage.Therefore,at the end of the thesis,the system inputs was completed in a sub-module.and the DPCH channel and S-CCPCH channel and the downlink composite multichannel whose time domain simulation diagrams of the FPGA implementation and the actual test diagrams of the oscilloscope are given,which are proved to be correct.