Research And Implementation Of Key Technologies Of Broadband Cognitive Communication System Based On LTE

This thesis takes the Physical Downlink Shared Channel(PDSCH)as an example,to study the physical layer baseband part of the broadband cognitive communication system's fixed-point implementation based on the TD-LTE wireless communication protocol in the TMS320C6670 multi-core DSP(Digital Signal Processor)and the application of several classic interference detection and suppression algorithms in Physical Downlink Shared Channel.The thesis first introduces the development history and research value of broadband cognitive communication system and the importance of interference detection and suppression technology in broadband cognitive communication system.The thesis studies the wireless communication protocol architecture and physical layer resource definitions based on TD-LTE,And add interference sensing function modules to the protocol architecture to form an improved protocol architecture suitable for broadband cognitive communication system.Based on the downlink shared channel of the broadband cognitive communication system,the thesis studies the interference detection and suppression technology in the non-silent period.The thesis studies and analyzes the performance comparison between the CME and FCME in the silent period when there is no valid signal and the performance comparison of FCME algorithm for interference detection in the absence and presence of signal.FCME is determined as the method of interference detection.The interference suppression algorithm is studied for the three interference modes of single tone,multi-tone and narrowband in the non-quiet period.In the case of single tone interference,the FFT-MLE(Fast Fourier Transform-maximum likelihood estimation)and FFT-MLE-based Iterative algorithm of two frequency reconstruction cancellation algorithms for simulation analysis and performance comparison.For multi-tone interference,the performance of frequency notch and FFT-MLE frequency reconstruction cancellation is analyzed and compared under different parameter combinations.Digital simulation shows that when several single-tone interferences are far away,the reconstruction algorithm has better interference suppression performance.When there is close single-tone interference,by increasing the number of input symbols,the FFT-MLE frequency reconstruction algorithm can maintain good performance.In the case of narrowband interference,the performance of the FCME-based double-threshold algorithm and the overlapped windowing filter algorithm is analyzed and compared,and the interference factor on the performance of the overlapped windowing filter algorithm is studied.Finally,the thesis studies the design and implementation of the perception link of the broadband cognitive communication system,completes the design of the data and perception communication protocol between DSP layer,MAC layer and the FPGA layer,and conducts a joint functional test of the entire system to verify the accuracy of the system implementation.The thesis completed the overall operation logic design of the perception link of the broadband cognitive communication system,and carried out specific implementation research for the DSP layer in the system.The thesis was based on the Ethernet port and SRIO(Serial Rapid Input/Out Put)interface design and implementation and jointly tested the DSP The data and signaling interactions with adjacent layers are tested for downlink normal service data transmission and peak rate service transmission to verify that the DSP can still operate stably under full-rate transmission.The sensing initialization and sensing channel and switching functions are tested to verify the accuracy of the sensing link design and implementation.The thesis cooperates with the high-level protocol stack,digital intermediate frequency and radio frequency unit to complete the overall joint test of the broadband cognitive communication system,verifying that the terminal video backhaul and terminal video call functions of the system meet the project requirements.