Network Transmission Study

With the explosive increasement of Internet and the continuous emergence of new services, Internet is suffering some performance depravation problems, and network congestion is one of the severe problems, which limits the development of the network. At the same time, the multimedia services which are sensitive to delay and delay jitter enrich the network resources, but also put forward the question of how to assure its quality in network. Therefore, the investigation of network congestion and the delivery quality of multimedia transmission is important to improve the network performance and reform the service quality.In this paper, some issues in active queue management (AQM) algorithms and the delivery quality of multimedia transmission are studied, which are detailed as follows:(1) A stabilizing and parameter adaptive PID algorithm (FIMC-PID) based on internal mode control (IMC) and fuzzy control is proposed, which is in order to eliminate the negative impact on stability caused by large communication delay. In FIMC-PID, the filter time constant of IMC is optimized by using fuzzy algorithm. Simulation results show that large delay can be effectively compensated in FIMC-PID, and stability and robustness under different number of loads and different bandwidth of bottleneck link is also superior to PID.(2) Based on the CSFQ algorithm, RQ-CSFQ is proposed to solve the problem of bad fairness in mixed traffic and sensitive to the variety of RTT and burst traffic in CSFQ. In RQ-CSFQ, the cache management strategy similar to RED is adopted, and the queue length is concerned to improve the estimate of fair share rate a and loss probability. Simulation results show that the merit of CSFQ is inherited, the fairness in mixed traffic is improved, and the impact of variety of RTT and burst traffic can be also effectively solved in RQ-CSFQ.(3) The effects of queue management to the delivery quality of multimedia transmission are studied and analyzed by simulation, and based on the RIO-C algorithm, gentle-RIO-C algorithm combined RIO-C with gentle-RED is proposed, which is in order to improve the robustness of RIO-C, simulation results show that the delivery quality of multimedia transmission of gentle-RIO-C is better than RIO-C. Moreover, the effects of other factors to the delivery quality of multimedia transmission are also studied and analyzed by simulation.