Design Of Low-latency Wireless Digital Image Transmission System Based On LDPC-OFDM Coding

At present,low-latency high-definition wireless image transmission technology has a wide range of applications in the military and civilian fields.To solve reliable low-latency wireless image transmission,the main problems faced are that the first high-definition image transmission requires a larger signal bandwidth.Large,the wideband communication signal is greatly affected by the channel under the multipath fading channel,and the communication performance will be greatly deteriorated.The second image transmission requires high communication quality and requires extremely low bit error rate of the communication system.Third,image transmission needs to meet certain real-time requirements in many occasions,which requires the entire system to have a relatively low transmission delay.This paper designs and implements the baseband signal processing part of an LDPC-OFDM low-latency wireless digital communication system for these issues.The main tasks are as follows:According to the overall design index of the system,the corresponding index requirements of the baseband signal processing part of the LDPC-OFDM wireless communication system are proposed.And around the proposed index requirements,refer to the existing mature standards to give the implementation block diagram of the LPDC-OFDM wireless communication system,and determine and optimize the main parameters of the system implementation according to the index requirements.According to the basic principles and common algorithms of OFDM modulation and demodulation and LDPC encoding and decoding,the OFDM modulation and demodulation algorithm and LDPC encoding and decoding algorithm were simulated respectively,and the corresponding performance curve was obtained and the two were combined on this basis.A joint algorithm simulation was carried out,and the system parameters were further optimized using the algorithm simulation results and the feasibility of the system design scheme was verified.The main modules of the OFDM modulation and demodulation algorithm are implemented in FPGA hardware,and the implementation results are verified by Modelsim software,and the correctness and feasibility of the hardware implementation are verified by comparison with the algorithm simulation results.The LDPC codec is implemented in FPGA hardware.Adopting quasi-cyclic LDPC codes,using an iterative structure encoder and an improved TDMP decoding method,to achieve a low-latency and high-throughput high-efficiency LDPC codec,and passed Modelsim to verify the correctness of the implementation And feasibility.Integrating the OFDM module and LDPC codec module implemented by FPGA,a hardware test system was constructed to perform hardware function test and bit error rate index test under equivalent low communication channels.The functions and performance indicators of the LDPC-OFDM wireless digital communication system are verified under the FPGA hardware platform.The test results show that the hardware system designed and implemented has reached the design index requirements and can meet the design requirements of the low-latency wireless video transmission system.