Research And Implementation Of Differential DAPSK Modulation Technology Based On OFDM

Orthogonal frequency division multiplexing(OFDM)technology has the advantages of high transmission rate and strong anti-multipath interference,so it is widely used in the field of wireless broadband communication,and it is the key to the fifth generation of mobile communication technology.Differential amplitude phase shift keying(DAPSK)has a simple implementation method and can obtain good performance without channel estimation.The thesis combines OFDM technology and DAPSK modulation technology,comparative analysis of OFDM time-domain differential DAPSK modulation and OFDM frequency-domain differential DAPSK modulation under different channel environment bit error rate performance,and implemented Xilinx ZYNQ 7Z020 chip OFDM time-domain differential DAPSK modulation system.The main research contents are as follows:(1)This paper analyzes and compares the bit error rate performance of OFDM time-domain differential DAPSK modulation,OFDM frequency-domain differential DAPSK modulation,and OFDM QAM modulation in different channel environments.QAM modulation uses block pilot channel estimation,and DAPSK modulation uses all Incoherent demodulation.The simulation results show that: under the channel environment with large time-varying,OFDM time-domain differential DAPSK modulation has better bit error rate performance than OFDM QAM modulation.OFDM time-domain differential DAPSK modulation does not need to insert pilots for channel estimation,which reduces the complexity of the receiver hardware implementation and improves the information transmission rate;it is verified that the OFDM frequency domain differential DAPSK modulation is more sensitive to frequency selective fading channels.(2)This paper designs and implements the transmitter and receiver modules of the OFDM time-domain differential DAPSK modulation system.The parameters and frame structure of the physical layer of the entire system are designed.The Verilog language is used to realize the transmitter and receiver of each module of the baseband part,and the output timing results are compared with the simulation tool to verify the correctness of each module.(3)This paper builds a hardware processing platform for the OFDM time-domain differential DAPSK modulation system,analyzes the hardware resource consumption of the baseband part of the entire transceiver link,and performs bit error tests on the transmitter and receiver.The baseband processing part is implemented using the ZEDBOARD hardware development platform,and the RF transceiver part is implemented using the AD-FMCOMMS2-EBZ evaluation board.The resource proportion statistics table provided by the Vivado software shows that the baseband part of the entire system consumes few hardware resources.Through the indoor environment BIST loopback test,point-to-point coaxial test and point-to-point wireless transceiver test,the data transmission rate of the entire system is 24.76 Mbps,and the bit error rate of the wireless end-to-point test is on the order of 1/10,000 to 1/1000,which verifies that the system can achieve high-speed data transmission.