A Connectivity-Driven Retransmission Scheme Based On Transport Layer Readdressing

Migration between different wireless access networks often involves disconnected period, which is caused by passing an area of bad wireless coverage and potential overhead to switch the network on the network interface to connect to. The disconnected period can cause extra transmission delay due to the timer-driven retransmission behavior in the transport protocols, such as TCP and SCTP. We propose a new retransmission scheme to achieve better migration performance in SCTP, which is a newer connection-oriented and reliable transport protocol that is becoming popular. Our scheme minimizes the extra transmission delay by leveraging address reconfiguration operation in SCTP without involving other layers. It decreases the delay more than 5 seconds compared to the original SCTP when migration involves approximately ten-second disconnected period. The implementation of our scheme is already imported in FreeBSD.