Research And Verification Of Key Technology Of 2x2 MIMO-OFDM Waveform Design

This paper designed and implemented a complete fundamental 2x2 MIMO-OFDM link, implementated and verified the physical layer data transmission using u SDR software-defined radio platform.Firstly, the key technologys MIMO-OFDM system including Alamouti STBC coding, MIMO symbol detection, channel estimation, timing synchronization algorithm, carrier frequency offset estimation algorithm were researched.And this paper compared the performance and implementation complexity of various algorithms through simulation, and selected the algorithms used in this link.Secondly, according to the requirement of the link, this paper built the complete simulation link, acquired the simulation results of the performance of the link. Through the analysis of the key technologys, this paper selected the Alamouti STBC coding, ML channel estimation, timing synchronization algorithm based on the ZC sequence, carrier frequency offset estimation algorithm based on 4 same PN sequence, 1/2 convolution coding, QPSK modulation, channel bandwidth of 10 MHz, the sub-carrier spacing is 15 k Hz.Then, this paper implemented the physical layer link via System Generator. The whole link was divided into transmitter, receiver, digital frequency, time and frequency synchronization four key modules according to there funciton. This paper gave the detailed description of the implementation process of each module according to the top-down thinking,. Time synchronization module uses multiple matched filter structure to achieve. Digital IF structure divided into three levels.Finally, on the u SDR software radio platform, the function of the link was verified. This paper tested the communication functions and bit error rate performance of the link using hardware platform developed by our team. First, this paper tested the time synchronization module, coarse frequency offset estimation module, fine frequency offset estimation module. Then test the actual bit error rate curve of the entire link, fixed-point simulation results with a difference of about 1.8d B.The link implemented in this paper satisfied the demand,and achieved the transmition of text and voice information.2x2 MIMO-OFDM fundamental link’s implementation provided more waveforms for u SDR platform, and also laid a foundation for more complex link in the future.