Improvement And Optimization Research Of The Lightweight TCP/IP Protocol Stack

In recent years,the development of intelligent hardware is promoting the combination of traditional hardware and software.The ability of the network connection makes intelligent hardware more applicable with internet services.As an open source network protocol stack,LwIP(A lightweight TCP/IP stack)has been widely used in intelligent hardware products.LwIP is an open source TCP / IP protocol stack which can be ported to different platforms,so it can runs on the operating system or without it.Duing to its versatility characteristics,LwIP provide a full support of protocol and interface,and therefore it does no optimization design for special embedded environments.When the embedded resource is limited,for example,the frequency of the MCU is only 72 MHz and the memory is only 96 KB.If the system need to store and transmit a real-time picture,then LwIP may take up too much momory resources whick reduce the efficiency of transmission.In this case,it's required to research and optimizes the memory‘s usage and the efficiency of transmission for LwIP.Aiming at the problems of memory management and network protocol interface exit in LwIP when hardware resources are limited,this thesis analyzes the memory management mechanism,the kernel and transport layer protocols of LwIP.Through in-depth analysis of related issues,an optimal design has been achieved to improve the efficiency of data transmission and memory usage.Moreover,the efficiency of memory usage and data transmission has also been tested.This thesis mainly finished the following contents:1)This thesis deeply analyzed the memory management,message registration mechanism in TCP/IP kernel and multi-transport layer interface,and pointed out the inefficient of memory management as well as inadequate in transport layer afrom the perspective of the hardware architecture and software source code.2)The thesis designed and implemented a new memory management mechanism whick has unified the memory management interface and has a preferential allocation.This optimization reduced the overhead of multiple memory management in embedded system,and improved the utilization of memory.3)The thesis designed and implemented a streamlined transport layer interface,which replaced the two original transport layer interface of LwIP,reduced memory usage and improved the efficiency of data transmission.4)The thesis designed and implemented a common client framework of MQTT based on the improved LwIP,and the whole scheme has beed applied to achieve the actual project.In addition,through a series of test and analysis,this theise verified and compared the practicality and effect of improved LwIP.5)This thesis focuses on in-depth analysis of memory management,kernel message registration mechanism and transport layer interface in the LwIP,and proposed improvement scheme in the corresponding scene which has some practical value and reference value.