Improvement Research And Simulation Of The Transmission Mechanism Of Adaptive Forward Error Correction Code Based On The Multi-Protocol Label Switch Network

Computer network is developing rapidly. With new applications coming into being over the IP-based network ceaselessly, people require more on the quality of service (QoS) of IP-based network. The aim of QoS research is to work out the solution that can guarantee that the performance of network applications could satisfy the users. That's to say the bandwidth, delay, jitter, packet loss and so on should be limited into a certain range, which could be tolerated by users.This paper will explain two kinds of solutions that can guarantee QoS provision. The whole network architecture is the major consideration in one kind of solution. The other kind of solution focuses on the terminals of network. Because both of the solutions have advantages and disadvantages, the aim of our research is to work out a new solution that combines their advantages to ensure QoS provision.After analyzing FEC/ARQ transmission mechanism, we propose a novel transmission mechanism of AFEC (Adaptive Forward Error Correction) code in this paper in order to improve the jitter performance of FEC coding on the client end. The new mechanism ameliorates the method of information exchanging between the server end and client end. In the old mechanism, the server end does not transmit data until it receives the feedback message about the acceptance status of the previously transmitted data, which badly affects the jitter performance on the client end. The new mechanism adopts 2-level AFEC code, which allows the server to adjust the FEC redundancy and sending rate in accordance with the control messages feed back by the client. The server using the new mechanism does not stop sending data for the sake of the lack of the feedback message. Meanwhile, the mechanism adopts Multi Protocol Label Switching technique to ensure the timely and correctly transmission of feedback message from the client to the server, which can make the server know the up-to-date working conditions of the network.Based on the Network Simulator 2 platform, we simulate FEC/ARQ and AFECmechanism respectively. And both mechanisms are experimented on the same working condition and they are tested for 3 different conditions. The comparison between the NS2 simulation results of these two schemes proves that the newly proposed AFEC transmission mechanism can improve the jitter performance on the client end. Therefore, this mechanism provides a new method of enhancing the end-to-end QoS of real-time video transmission.