The Design And Implementation Of Multimedia Push System Based On Raptor Code

Information push technology will push content proactively to the user client which saves the user time and effort. There are two main ways of information push technology:point-to-point and point-to-multipoint mode.Along With the rapid development of Internet and the popularization of large-screen multi-function device, there are more and more multimedia services,which have big amount of data and long duration.The traditional way for multimedia transmission is point-to-point mode,which has many disadvantages.While the point-to-multipoint way can simultaneously provide services to a large number of users, save costs.It is more suitable for transmission of large quantities of multimedia data.Multicast transmission mode has no feedback channel and users in the network has different conditions. Different network conditions should use different coding redundancy.Here we need to construct or find a forward error correction code which can automatically adjust the encoding redundancy. This paper studies the channel coding techniques in multimedia multicasting push system. Raptor code is selected for the multimedia multicast push system.This paper deeply studies the characters of Raptor code,studies and finally implements the encryption algorithm of Raptor code,and take many performance tests and make detailed analysis about the ability of error resilience of Raptor code.To further verify the implementation of the Raptor encoding and decoding algorithm are correct and the good performance of Raptor codes, we set up a multimedia push system. Pushing system consists of two parts:server and client. Using Wi-Fi to imitate the wireless environment, the server push data to several clients(mobile phone terminal)which under different network conditions to imitate broadcasting system. The final experimental results show that the mobile phone in the good network condition can timely receive enough encoding symbols and successfully complete the decoding.While the mobile phone in the not so good network condition,easy to loss data, can eventually receive enough symbols and complete the decoding as long as the server keeps pushing encoding symbols.