Multipath TCP (MPTCP) is a transport layer protocol that allows network devices to transfer data over multiple concurrent paths, and hence, utilizes the network resources more effectively than does the traditional single-path TCP. However, as a relia
ble protocol, MPTCP still needs to deliver data packets (to the upper application) at the receiver in the same order they are transmitted at the sender. The out-of-order packet problem becomes more severe for MPTCP due to the heterogeneous nature of delay and bandwidth of each path. In this paper, we propose the forward-delay-based packet scheduling (FDPS) algorithm for MPTCP to address that problem. The main idea is that the sender dispatches packets via concurrent paths according to their estimated forward delay and throughput differences. Via simulations with various network conditions, the results show that our algorithm significantly maintains in-order arrival packets at the receiver compared with several previous algorithms.
