The Design And Implementation Of Wireless IP Transmission Protocol Basing On Header Compression And VxWorks System

With the development of wireless communication technology,the type of traffic and the amount of data transmitted are increasing rapidly,which makes the limited spectrum resources become more and more tense.In wireless IP networks,packet header compression can improve the utilization of spectrum resources,and its header compression efficiency can reach more than 90%.Therefore,the research of wireless IP transmission protocol based on header compression is of great significance.In this thesis,the header compression algorithm is used as the object of research,the research work mainly includes the following parts:1.The traditional header compression scheme is not suitable for high bit error rate(BER)and high time delay wireless link environment,to solve this problem,we use robust header compression(ROHC)algorithm to mitigate the high bit error rate and high time delay problem in wireless links.Based on the principle of compression of redundant information in load field,the compression strategy and encoding algorithm are improved,according to the characteristics of the wireless link,the compression mode,the compressed state and the type of data packet are determined,CRC cyclic redundancy check is used to detect whether the compressed and decompressed terminals are synchronous,so as to improve the robustness of the system.2.In the Linux system,the improved ROHC header compression algorithm is implemented and simulated,the specific compression and decompression process is given,and the data structures of compression end and decompression end are designed,the Linux system is tested,and the simulation data and analysis results are given.3.An improved compression algorithm based on reducing the SO packet length is proposed,when sending a packet,the context identifier in the SO package is omitted,at the decompression end,the context identifier is restored according to the intrinsic mechanism,and the average header length in the packet transmission process is reduced.Simulation results show that the improved algorithm can improve the efficiency of spectrum utilization compared with the original ROHC algorithm.4.Using the embedded real-time operating system VxWorks,and Wind River Workbench 3.0 integrated development environment,the network protocol stack and network device driver of VxWorks system are studied,and the corresponding data buffer pool is designed.Based on the architecture of VxWorks network,the process of sending and receiving messages and the system implementation mechanism of hook function are designed.Finally,the system test verifies that header compression can be successfully run on embedded VxWorks systems.