On the Use of an Increased Initial Congestion Window to Improve mSCTP Handover Performance

With the wireless landscape being rather heterogeneous, handover between different network technologies, so-called vertical handover, becomes key to a continued success for wireless Internet access. Recently, an extension to the Stream Control Transmission Protocol (SCTP) -- the Dynamic Address Reconfiguration (DAR) extension -- was standardized by the IETF. This extension enables the use of SCTP for vertical handover. Still, the way vertical hand overworks in SCTP with DAR makes it less suitable for real-time traffic. Particularly, it takes a significant amount of time for the traffic to ramp up to full speed on the handover target path. In this paper, we study the extent to which an increased initial congestion window on the handover target path decreases the transfer delay spikes in real-time video traffic experienced during a vertical handover. The impact on both standard and high-definition video traffic is considered. The results of our study suggest that an increased initial congestion window does indeed significantly decrease the spikes in the video traffic. However, the results also indicate that it does not resolve the problem altogether.