TCP/IP is the one of the most widely used transmission control protocols. This protocol has a simple congestion control mechanism. Nowadays, Random Early Detection(RED) and Explicit Congestion Notification(ECN) are introduced to solve the retransmission time delay, bandwidth wasting, and global synchronization which is made by existing congestion control mechanism. But there are throughput losses because of unsolved heavy fluctuation of window size yet. And RED bring about an unfair sharing of resources due to a long round trip time bias among connections. In this thesis, we suggest the modified window control algorithm to solve the fluctuation of window size using ECN. And we propose the solution about the unfair sharing of resources. In addition, we propose a new marking algorithm to prevent the marking probability to be accumulated. Finally, we check the performances of our proposed schemes by simulation.