Design And Development Of LTE-Unlisened Test Platform Based On Software Defined Radio

With the rapid development of mobile communication network and the ever increasing demand of mobile data, telecom operators faces many challenges in fulfilling the high data traffic demand. Though the licensed spectrum of cellular system has high spectrum efficiency, more additional spectrum is required, unfortunately this resource is very scarce. Therefore, extending LTE to a large number of underutilized unlicensed bands has become the trend of future development. However, the Wi-Fi has been deployed to the unlicensed spectrum that LTE seeks to use at 5GHz. This calls for an urgent study of the best mechanism which allows the two technologies to work together without mutual interference. As traditional ways such as computer software simulation and the analysis of the of pure mathematics theory have the problems of inaccuracy, time-insensitive and lack of real radio environment, this work intends to develop a Software Defined Radio(SDR) real-time test platform, for the test and verify interference coordination technology between LTE-Unlicensed(LTE-U)and Wi-Fi in real radio environment.With references to the different access mechanism requirements, this work first explored a new method of testing and evaluating the wireless communication technology, and SDR test platform scheme based on GNU Radio and USRP has been proposed. Compared with traditional research methods, the test platform based on SDR has the advantages of flexible, reconfigurable and extensible. It is very suitable for testing and verifying of the continuous development of wireless communication technologies.Combined with the modular programming ideas of SDR, this work analyzed the working principle and design solution of each module in detail. A sliding correlation coarse synchronization mechanism based on Cyclic Prefix(CP) was designed. The synchronous capturing and tracking at the receiving end based on synchronous signal was realized based on the GNU Radio development environment. Besides, a channel estimation algorithm based on Cell Reference Signal(CRS) was realized and the development of the Graphical User Interface(GUI) was completed.Finally, the typical scenarios for the performance evaluation of LTE-U single system as well as coexistence with Wi-Fi based on the test platform was designed. The test result shows that the test platform is stable, and can be used to test new wireless technology in unlicensed spectrum. The test results of ON/OFF algorithm accord with theoretical expectation. In general this work provides a foundation platform for the research and test of new LTE-U technology in real radio environments.