| Traditional wireless video transmission platforms are mostly designed based on dedicated hardware,which are large in size,high in cost and limited in working scenes and transmission modes.Because the platform based on dedicated hardware development is not reusable,it is usually only suitable for areas where communication performance does not need to be upgraded.With the rapid changes of wireless communication protocol and wireless communication platform technology,the demand for multimedia services such as video and other data transmission is increasing,which promotes the market demand for performance upgrading of communication systems.Full Programmable On-Chip System(APSOC)with flexibility and reusability emerges as the times require.Xilinx's Zynq7000 series is an extensible platform based on APSOC,which integrates ARM processor and FPGA into a single chip,and uses advanced extensible interface(AXI4)to highly couple the ARM and FPGA.This architecture facilitates the flexible updating of the whole system,while giving full play to the advantages of hardware and software co-processing,reducing the development cycle greatly.Aiming at the typical requirement of wireless video transmission and main challenge of limited working mode of communication equipment,this thesis designs a wireless video transmission system based on APSOC.The main contents are as follows:(1)The software and hardware co-design process and development environment based on APSOC,the reusable technology of intellectual property rights(IP)and the communication mechanism of AXI4 bus are studied.According to the requirement analysis of system performance,the software and hardware partition and overall design are completed.(2)The internal architecture,hardware and software resources,key IP cores and Lwip protocol stack of Zynq7000 are studied.On this basis,an efficient communication interface based on AXI4 bus is designed to realize the communication link between Ethernet port and baseband processor.(3)The algorithm principle of OFDM is studied.The main controller and each functional sub-module's hardware logic circuits of baseband transmitter are designed and implemented by using Verilog HDL hardware programming language,and the function simulation and board level verification are carried out.(4)The internal architecture,register resources and interface timing of AD9361 are studied.On this basis,the register configuration and working state control of AD9361 are completed.A high performance parallel interface based on LVDS mode is designed and implemented to realize data communication between baseband processor and AD9361.The design of the whole system is based on the key technology of APSOC,which makes full use of the advantages of hardware and software co-processing technology and IP resource reuse,and greatly improves the design efficiency and system performance.The system has the following characteristics:(1)The system integrates highly programmable performance of software and efficient computing performance of hardware.It has abundant software and hardware resources and flexible configuration.It can select appropriate baseband transmission parameters and processor resources according to the current communication environment,which improves the flexibility and versatility of video transmission system.(2)The digital baseband system adopts the OFDM processing scheme based on the IEEE 802.11 a protocol to deal with the changeable channel environment.Baseband processor is implemented by hardware,which is divided into two parts: controller and data channel.It meets the needs of high-speed communication,facilitates later algorithm optimization and hardware upgrade.(3)The RF part adopts AD9361 agile RF transceiver with high programmable ability,and integrates management with baseband processor through SPI control interface and LVDS data interface.AD9361 integrates multi-stage digital filter and digital-to-analog converter,which greatly simplifies the design of baseband system. |
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