Research And Implement Of Reliable Multicast Protocal For GEO Satellite Network

Since the high bit error rate and longtime delay in satellite network,it is inevitable to face the problem of reliability for multicast service.In addition,the space link can be easily affected by weather and other factors,leading to different receiving ends usually suffer from different loss tolerance,even a bursting packet loss,etc.All the problems put forward to a big challenge for the reliable transmission of multicast traffic.This thesis mainly concerns about the multicast feedback mechanism for reliable multicast protocol in satellite network,the key elements about the paper are as following.Firstly,the present situations of reliable multicast protocol and multicast feedback mechanisms have been discussed.The paper elaborated the definition and classifications of reliable multicast protocol,its key technologies are also summarized in details.Then the current situation of multicast feedback mechanisms was introduced and analyzed.Secondly,a new timer-based multicast feedback mechanism named P-MFB was proposed to solve the problem of feedback compression that not properly optimized for the Multicast Feed Back mechanism in GEO satellite network.The new mechanism is improved mainly based on the protocal NORM,on the one hand,we optimized the ERB algorithm,a multi-priority exponential random back off algorithm name as MERB was presented;on the other hand,the timing of starting feedback on receiving end in MFB was also improved to be closely combined with MERB algorithm to achieve a greater feedback compression and increase the bandwidth utilization of the space link.Third,based on the P-MFB mechanism,the NORM protocol is improved,and a new reliable multicast protocol based on satellite network is proposed named NORM+.Compared to the NORM protocol,NORM+ mainly improved the following three aspects,which including back-off algorithm,multicast feedback mechanism,and block coding mechanism.Finally,an experimental platform was set up to complete the experimental evaluation for NORM+ protocol.The results validate that comparing to NORM,the NORM+ protocol can realize greater feedback suppression and improve the bandwidth utilization of entire multicast link in satellite networks under complex environments in satellite network.