The Measurement Of TD-SCDMA Code Domain Parameters And The Research Of Signal Processing Method

The TD-SCDMA is an international mobile communication standard proposed byChina for the first time, and the independent intellectual property of physical layer coretechnology is fully developed and owned by China. Compared to WCDMA andcdma2000, TD-SCDMA is a new communication standard, whose technology andcommercial experience is not very mature. Therefore, extensive testing is required toensure the smooth progress when it comes to commercial use, and the terminal RFparametric testing is an important part throughout the whole testing process. There areseveral terminal RF parameters need to be tested, For instance, channel power, occupiedbandwidth, adjacent channel power leakage ratio, error vector magnitude, code domainpower, peak code domain error, constellation diagram, eye diagrams, bit-rate and so on.Up to now, only Agilent, Tekronix and CLP41companies can provide TD-SCDMA testsolutions, however, most of them are dedicated to testers, only few can supportspectrum analyzer measurement functions.In this dissertation, a study on the TD-SCDMA physical layer signal processingmethod is conducted on the basis of PXI real-time spectral analysis module, and finallysome measuring specifications can be drawn in the form of vivid picture. Besides, thedemonstration of several important parameters, including error vector magnitude, codedomain power, peak code domain error and the bit table, are calculated to show themeasuring specifications. The interface for parameter calculation is written by Clanguage. In order to determine these parameters, the key point of this work isrecovering the ideal reference signal by the measured signal and it is also the main workof this thesis. By adopting the idea of recovering the ideal reference signal afterstudying the physical layer is the innovation of this thesis. The main work is as follows:（1）The core technology of the physical layer on uplink is studied firstly, whichincludes coding and decoding and multiplexing and demultiplexing of the transmissionchannel. The specific implementation algorithm of each module is discussed and then asimulation model of multiplexed coding and demultiplexed decoding process is created.Each module algorithm is achieved with C language S-function. Finally, the bit error rate simulation result is given, which verifies the correctness of the algorithm.（2）The data stream is modulated, spread, scrambled and inserted into the trainingsequence code and the pulse forming process, and then is transmitted in the wirelesschannel. The spectrum modulation and spread are analyzed in the dissertation,especially the algorithms of each module to achieve spectrum spread are discussed, andthen the simulation model of the spread spectrum modulation links is given, in the endthe TD-SCDMA signal is created.（3）A method of restoring ideal reference signal from the test signal has beenproposed, as well as some methods of measuring key parameters such as Error VectorMagnitude, Code-Domain Power, Peak Code-Domain Error and Bit-Table, from boththe test signal and the reference signal. The interface of functions which calculates theparamters has been C programmed, and the algorithm of parameters measurement hasbeed simulated and verified. Finally, the EVM algorithm interface is embedded into theupper software layer and the test result is compared with the result of TektronixSpectrum Analyzer.