TCP SPC: Transport Control Protocol Using Statistic Process Control

With the extensive application of wireless networks, more and more researchers focus on the theories and technologies of wireless networks. Since TCP has already played an important role in wired networks, improving the dissatisfactory performance of TCP in wireless networks is significant.In this dissertation, we proposed a new transport control protocol, named Transmission Control Protocol Using Statistic Process Control (TCP SPC), to improve the performance of traditional TCP in wireless networks. By combining the statistics and computer science, the Statistic Process Control (SPC) is introduced into TCP SPC to enhance the congestion control mechanism. TCP SPC employs the SPC mechanism to record the variety of RTT, thus the congestion state can be distinguished.In this dissertation, we firstly analyzed the rationality of employing RTT as the congestion indicator. Secondly, we verified that the RTT approximately obeys the normal distribution in wireless networks with invariable load, which is the premise of employing SPC. Thirdly, we described the basic principle of TCP SPC. The RTT statistics and the control values of SPC are continually estimated and calculated by TCP SPC. Furthermore, we employed a control chart and sets of congestion criterions to describe and monitor the change pattern of RTT. Since the different congestion states of the network can be inferred by the satisfaction of different criterion sets, TCP SPC is able to adjust the congestion window effectively according to the congestion states. Therefore, the congestion state can be distinguished accurately and statistically; meanwhile, the impact of packet-loss due to the link error can be effectively reduced.Finally, in order to verify the validity of TCP SPC, we implemented TCP SPC. In order to compare the performance of TCP SPC with other TCPs', we evaluated its performance in many scenarios. The simulation results show that TCP SPC can significantly improve the end-to-end throughput without reducing the fairness too much. Therefore, we can draw a conclusion that the TCP SPC is an outstanding general transmission control protocol.