QoS-based TCP Congestion Control Mechanism And Scheduling Algorithm

In recent years,with the rapid development of network applications,the demand for quality of service(QoS)is becoming higher and higher.Because TCP protocol was originally designed for wired networks,the traditional TCP protocol will lead to the decrease of network throughput and the increase of packet loss rate and delay when it is applied in heterogeneous networks with complex structure.The throughput,packet loss rate and time delay are the evaluation factors of the quality of service(QoS).The decline of the performance directly leads to the decline of the quality of service(QoS)of the network.The content of this paper is as follows:The performance of the network will decline and QoS can't guaranteed When TCP is used in heterogeneous networks.On the one hand,the compatibility of TCP and wireless networks is poor.In congestion control mechanism,the change of congestion window value can't be dynamically adjusted according to the network load,which leads to the increase of packet loss rate and the decrease of throughput.On the other hand,the TCP protocol does not distinguish the priority to the traffic and can't guarantee the demand of the high priority traffic.An improved congestion control model based on predatory model-Q-IPPM(Internet Prey-predator Model)model is proposed.The model can initialize the congestion window according to the queue length and network bandwidth in the process of congestion control,so that the network can run in a good state,and can control the traffic proportion of different services in the network according to the load status and priority of different services.Secondly,based on the Q-IPPM model proposed in this paper,an automatic confirmation mechanism based on TCP agent is proposed for the instability and random competition of the wireless network,and a scheduling algorithm is added to the wireless gateway node.On the one hand,the wireless gateway node can reply the ACK information of TCP protocol at the first time,so as to reduce the occurrence of TCP timeout event,reduce network overhead and improve the throughput of wireless network.On the other hand,the scheduling algorithm can optimize the delay and throughput of QoS services,and better guarantee the QoS of high-priority services.A large number of simulation results show that the Q-IPPM model can't only improve the throughput of heterogeneous networks and reduce the packet loss rate,but also allocate the bandwidth to different services according to the service priority and load status.The scheduling algorithm designed for the wireless network has a good improvement in time delay,packet loss rate and jitter rate,thereby ensuring the QoS of heterogeneous networks.