Research And Improvement Of The TCP Congestion Control Over Space-Air Integrative Information Network

With the development of aeronautics and telecommunication technologies, the Space-Air integrative information networks will be expected to guarantee people enjoying interactive multimedia services"with anybody, at anything, in anyplace". However, compared with the wired environment, the characters of Space-Air integrative information networks are high bit error rates, low bandwidth, long time delay, frequency moving and so on. In Space-Air integrative information networks, congestion is not the only reason for data losing. If we use the traditional congestion control technique in Space-Air integrative information networks, it can make the sender decrease the sending rate unnecessarily and result in the decrease of the network performance. Therefore, it is important to design an efficient TCP Congestion control algorithms to improve network utilization in the space of the Space-Air integrative information networks. It can avoid congestion and quickly come back ideal rate, so users possiblely maintain a stable and relatively high speed of data.Based on the national 863 plan"Network Management&Interconnection of **", the dissertation includes two aspects to research on the Space-Air integrative information networks congestion control.Firstly, the TCP theory and the key technology of TCP congestion control algorithm are researched in the dissertation. At the same time, a few TCP congestion control algorithm (such as Tahoe, Reno, Sack and Vegas) are compared and the key technology of TCP congestion control algorithm is discussed.Secondly, in the implementation of congestion control algorithms, the congestion window smooth growth of TCP congestion window, the bigger initial window in slow start period and real-time link bandwidth estimation is adopted to improve the congestion control algorithms, which enhanced the real time performance and decreased the influence on throughput of the reverse packet loss rate. Our extensive simulation results show that new congestion control can improve the performance of TCP congestion control at the start of a TCP connection or after a retransmission timeout, thus significantly improve throughput of Space-Air integrative information networks. Futhermore, the new congestion control can also be easily implemented and deployed since it requires only the sender side to be modified.