Research On Wireless High Definition Video Transmission System Based On COFDM

In the information age,people increasingly choose wireless HD video as the information carrier,but in some emergency communication fields,video transmission under the public communication system is no longer applicable.The emergency communication system is different from the public communication system in that its application scenario has certain burstiness and complexity.The basic requirement is to quickly provide rapid communication through quick and convenient means,which is a supplement to the public network.Today's common high-definition video communication system are basically developed for the public network,and cannot adapt to the special needs of emergencies and complex environments.To supplement the limitations of video communication system,this thesis designs a wireless high-definition video transmission system based on COFDM(coded orthogonal frequency division multiplexing).The system is superior to other video communication systems mainly in reducing the amount of transmitted data by using H.264 compression coding;using COFDM as a modulation technology makes the system strong anti-interference ability and can transmit high-rate video streams;using AD9361 reduces the overall system power consumption.This thesis mainly completed the work:In the video coding part,H.264 encoding based on Hi3516 A is completed,and the encoding delay is optimized.In order to adapt to the subsequent module to carry out TS(Transport Stream)packing for H.264 code stream,TS stream can be compatible with more devices.Data transmission based on LWIP(Light Weight IP)protocol stack and FPGA(Field Programmable Gate Array)is adopted,which can adapt to multiple transmission rates and is simple to implement.In the baseband modulation section,the channel and coding are analyzed.The implementation of the DVB-T(Digital Video Broadcasting)digital TV standard to write the baseband processing module.The upper board simulation verification function is performed for each module.This thesis also proposes several ways to save the resources of the FPGA system and reduce the performance loss.In the upconversion part,the AD9361 radio frequency transceiver scheme is adopted.The scheme different from the discrete device construction scheme in that the software radio architecture is easier to achieve different frequency bands and modes,with small board area and lower power consumption.Compared with the general no-os configuration mode,this design improves the configuration speed by using the FPGA to configure the AD9361 mode.In the system test part,the correctness of coding and packing is analyzed by software,and the baseband modulation system is verified by joint debugging.The signal is transmitted through AD9361,then received and demodulated by RTL-SDRn and sent to PC for playback.The playback effect is well.The transmitting system can achieve the expected transmission of high-definition video.