Research And Realization Of Robust Header Compression In LTE System

With the rapid development of mobile communication and its constant fusion with thebroadband wireless access, people’s demand for broadband mobile communicationbecomes more urgent. In order to accomplish the mobilization, broadband and IP of thenew generation mobile communication system,3GPP, on the basis of3G, begins toresearch on a new generation mobile communication system---LTE. On onehand,supported by full IP carrying, LTE system has higher data rate and system capacitythan the wireless system ever before, making the contradiction between the spectrumresources and service flow more acute, on the other hand, relying on IP-based network,when running voice, video etcthrough IP network,overlargeIP header packet occupiesprecious bandwidth of wireless channel, causing great waste, consequently, it isparticularly important to apply strong header compression technique in LTE system.ROHC is a robust header compression technique proposed by IETF tospecificallysolve the problems of high error rate and long transmission delay in wirelesslink. It greatly improves the utilizationof wireless bandwidth resource in the premise ofguaranteeing robustness. Now,3GPP regards it as the standard of3G and LTE mobilecommunication system technology and applies it in sublayer PDCP to improve theutilization rate of bandwidth under wireless environment and provide users with bettersupport in multimediaservice.Firstly, the thesis introduces the technical background of the LTE system and thenelaborates on ROHC protocol framework, including basic principles, working condition,working mode, transition logic among all kinds of states and modes, feedback mechanism,error check and context repair mechanism.Moreover, the thesis analyzes the maincompression algorithm of ROHC protocol and has some discussions on its modificationand realization. Based on thechecking technique of wireless channel condition in MAClayer,an improved compression algorithmof adaptive sliding window is put forward on thefoundation of LSB/WLSBin order to adapt to the changingenvironment of wireless link. The compression efficiency and robustness of ROHC can be considered as well. Thedesignof whole ROHC system in LTE is realized by using C language programming. Throughsystem testing, it is proved that the design proposal offered by the thesis is available andrealizable; since the transmission rate of air interface can meet the requirement of LTEprotocol standard and effectively improve the efficiency of system throughput.