Research And Application Of Reliable Multicast In Wireless Network

With the development of Internet Technology and the improvement of Network Transmission Rate and Quality,the demand for multimedia files,such as HD video,audio and so on,is becoming more and more common.However,because these types of files mostly are relatively large,when these files are transferred over Internet they will take up more bandwidth resources.Therefore,how to make efficient use of network bandwidth resources and achieve high-speed and reliable data distribution,has become an important research topic.In order to realize the high-speed distribution of multimedia files in the wireless network data distribution system,through the analysis and research of the main data distribution methods,a multicast data distribution system is proposed in combination with the actual demand on real-time,high efficiency and reliability.This thesis improves the performance of the distribution system from two aspects: multicast protocol and application layer coding.In the aspect of multicast protocol,the idea of associating the contents of the packet with the transport file is introduced on the basis of the existing ALC protocol.In this way,the terminal could know the contents of the file represented by the information in the packet when receiving the packet.In the aspect of application layer coding,after the research on a variety of fountain code technology,a selective decoding method is proposed which combined Dimensionality Reduced Fast Decoding and Optimized Inactivation Decoding Gaussian Elimination.According to the situation of the number of terminal receiving data packet,the terminal select an appropriate decoding method to improve the decoding efficiency.Finally,the efficiency of the decoding method will be verified by some simulation experiments.The main contents of this thesis is as follows:(1)Based on current fountain code technology,a selective decoding scheme is proposed to solve the problem of time delay and decoding failure caused by RaptorQ decoding process.This scheme could help receiver select an appropriate decoding algorithm according to the packet loss rate,which could improve decoding efficiency.(2)Based on the original ALC Protocol,File Delivery Table Mechanism is added to the multicast transport protocol.When the data file is transferred,the file attribute would be stored into FDT and transmitted together with data packet.This type of transmission makes the receiver to know the contents of the packet and restore it quickly after receiving the packet.Because of adopting RaptorQ Code into application layer coding,FDT could help receiver classify data packet as quickly as possible.This operation is very convenient to decoding in the next step.(3)At last,we design and implement the prototype model of the multicast distribution system using RaptorQ code.And then,the design of multicast data distribution program is validated through experimental testing.