Video transmission by MPTCP multi-path transfer protocol over heterogenous wireless network. -- 2

Our simulation topology is illustrated . MPTCP establishes three subflows, A, B and C, between the server and the client. Each path consists of wired and wireless links. In real networks, the transmission rate is usually limited by the wireless links, so we set enough bandwidth for the wired links, and the wireless bandwidths of three subflows are 2Mbps, 3Mbps and 4Mbps, respectively. The total path delay of subflow A is 100ms, with 0.5% packet loss rate; the total path delay of subflow B is 50ms, with the same packet loss rate as subflow A. Subflow C has the best condition of bandwidth, but the worst condition of path delay, which is 200ms in total. As the packet loss rate and receiving buffer size are two main factors affecting the packet reordering in MPTCP, we change the packet loss rate of subflow C from 0.1% to 3% and the receiving buffer size from 16KB to 512KB in different simulations, to evaluate the three scheduling mechanisms. The simulation time of MPTCP transmission is 100s. The routers adopt the abandon tail queue model with the maximum length of 100 packets. The Maximum Segment Size (MSS) of TCP packet is set as 1400 bytes, the smoothing parameters α, β and γ are selected to be 7/8 according to [12]. All the presented results are the average of 100 simulations, in avoidance of the random noise.