The unreliable-concurrent multipath transfer (U-CMT) protocol for multihomed networks: U-CMT

Many real-time applications, such as Video on Demand, are sensitive to the transmission delay and allow data loss. Computing devices in multihomed networks are equipped with multiple interfaces such as 3G and Wi-Fi. This work presents an Unreliable Concurrent Multipath Transfer (U-CMT) protocol that satisfies requirements of real-time applications running on multihomed devices. U-CMT is based on Stream Control Transmission Protocol Partial Reliability Extension (PR-SCTP) and the Concurrent Multipath Transfer (CMT) protocol. The novel features of U-CMT are (1) allowance of data loss, (2) sequential data delivery, (3) congestion control, and (4) multipath data transmission. During multipath transfer of unreliable data, congestion control of PR-SCTP may become useless, and receiver buffer blocking occurs. U-CMT uses Path Sequence Number (PSN) to identify data transmission sequence on a per-path basis. The receiver is able to abandon lost data using PSN. As a result, the occurrence of receiver buffer blocking is reduced. Comparing with other protocols, the simulation results show that U-CMT achieves better stable playable frame rate in multihomed networks.