An unreliable concurrent multipath transfer protocol over multihomed networks

Real-time and multimedia applications require less reliability but are sensitive to the transmission delay on data transmission. Current unreliable transport layer protocols do not have congestion control and concurrent multipath transfer features at the same time. In this paper, we propose an Unreliable-Concurrent Multipath Transfer (U-CMT) protocol, which features with (i) concurrent multipath transfer, (ii) congestion and flow control, and (iii) unreliable data transmission. Data in U-CMT are transmitted only once and never retransmitted. U-CMT adopts the similar idea of SCTP Partial Reliable extension (PR-SCTP) to transmit unreliable data. However, (i) flat congestion window and (ii) zero flight size phenomena may exist, which cause the congestion control mechanism to be useless, when using PR-SCTP to transmit unreliable data. U-CMT can eliminate the above two phenomena through the way of delaying marking data chunks as abandoned. Thus, U-CMT can precisely infer cwnd and flight size the same as SCTP. U-CMT also utilizes all paths for data transmission. The simulation results show that U-CMT can have better video streaming quality in the congested network.