Research On The Key Technology Of Spectrum Adaptive Communication Waveform And Impliment With FPGA

In order to meet the increasing demands,the data rate,reliability and anti-jamming capability of aeronautical communication have to be significantly inproved.In this disseration,based on the non-continuous orthogonal frequency division multiplexing(NC-OFDM)technology with spectrum sensing data,the key generation and reception technologies of spectrum adaptive communication waveform are implemented in the FPGA(Field Programmable Gate Array).The first chapter of the dessertation briefly introduces the importance of multi-carrier communication technology.Based on the introduction of OFDM(Orthogonal Frequency Division Multiplexing)technology,the possibility of applying NC-OFDM(Non-Continuous Orthogonal Frequency Division Multiplexing)to spectrum adaptive system is disscussed.In the second chapter,the link model and the system development platform are presented.For the link model the function and principle of the moodules are describel.For the development plateform,both the baseband and the RF board are introduced.The baseband board contains two TI 2C6670 digital signal processor(DSP)and two Xilinx FPGAs.The DSP is used to perform the tasks of encoding and decoding,interleaving and scrambling.Meanwhile,the FPGA is used to perform the transformes' s digital baseband signal processing.The RF board transformes the baseband data onto the high frequency carrier and filters the transmitted and received signals at the same time.In the third chapter,the key technologies of spectrum adaptive multi-carrier waveform are inverstigated,and the FPGA implementation of these technologies is described in detail.For the transmitter,the FPGA implementation includes data mapping,Cyclic Code Shift Keying(CCSK)modulation,pilot symbol generation,OFDM modulation,synchronous sequence generation,out-of-band radiation suppression and framing,Peak to Average Power Ratio(PAPR)suppression.For the receiver,the FPGA implementation consists synchronization,de-frame and interference suppression,OFDM demodulation,channel estimation,16QAM(quadratrue amptitude modulation)soft demodulation and CCSK hard demodulation.The fourth chapter introduces the SRIO(Serial Rapid Input/Output)and CPRI(Common Public Radio Interface)interface protocols used in platform development,and provides the corresponding FPGA implementations.The implementation of the SRIO interface is based on the Xilinx's rio_wrapper solution.The SRIO interface data transmission is implemented by two data transmission modes,which are SRIO logic layer SWRITE and DOORBELL.CPRI interface implementation is based on the CPRI core.According to the link rate and the interface rate,the transmitted baseband I/Q(In-phase/Quadranture)data are mapped into the basic frame of the CPRI interface by the backward compatible mapping method.At the same time,the received the basic data frame is converted to the baseband data.In chapter 5,the performance of FPGA is verified.First,the performance of the frequency offset estimation module is tested.The results show that the frequency offset estimation module can estimate the frequency deviation very accurately at the system operating point,for which the frequency offset estimation of large frequency offset must be satisfied in the cruise scenario.For the PAPR module,the test results shows that the PAPR suppression module can effectively suppress the PAPR of the transmission signal and meet the system requirements.Furthermore,the channel simulator is used to simulate the Gaussian channel and the cruise channel for the performance evaluation.Moreover,the scenaraio with 20% partbband jamming is also considered in the performance evaluation.By comparing with the simulation results,the test results verify the effectivence of the implementation.Finally,the performance of the whole link including channel coding is tested.The results show that the system can achieve desirable performance,and meet the requirement of the aviation communication system.In Chapter 6,summarizes the full text and puts forward the prospect and direction of the work.