Research And Optimization Of Reliable UDP Protocol

With the rapid development of Internet technology,traditional TCP gradually exposed many problems that people had not taken into account before design.O n one hand,with the continuous increase of network bandwidth,the efficiency of TCP in high bandwidth delay product network was reduced,on the other hand,with the development of wireless access technology,the performance of TCP in heterogeneous network decreased quickly.In order to transmit data efficiently and reliably,one scheme is to obtain high transmission performance by improving existing TCP,and the other is to achieve efficient and re liable data transmission on UDP.Because of the high cost of TCP,the second scheme is chosen in this paper and the main work and achievements of this paper are as follows:(1)In order to increase the accuracy of RTT estimator of RUDP,a higher precision RTT estimation method with dynamic time-averaging factor is formulated and the performance of the improved method has been analyzed by experiments.The results show that the improved RTT estimation method has lower Minimum Mean Square Error(MMSE)and higher estimation precision than the original method.(2)Available bandwidth estimation mechanism is introduced into RUDP,and an available bandwidth estimation method based on RUDP throughput is proposed.To eliminate the effects of asymmetric link,reverse link congestio n and other factors,the proposed method estimates bandwidth at destination side and feeds back to source side,thereby improving the accuracy of bandwidth estimation.(3)To improve the weakness that RUDP cannot distinguish the type of lost packet,a loss differentiation mechanism based on round trip time is introduced into RUDP,thereby eliminating the effects of random packet loss.(4)To improve the congestion control mechanism of RUDP,an improved congestion control mechanism based on available bandwid th estimation with loss differentiation mechanism is proposed on the basis of section 2 and 3,and the throughput performance of RUDP is improved effectively.(5)The reliable UDP protocol model on OPNET is established,and the improved methods mentioned above were analyzed by this simulation model.The results show that the proposed reliable UDP transmission scheme has higher throughput performance in heterogeneous network and long fat network,moreover,it has good flow fairness in the coexistence of multi flow.