Mankyu Park

Adaptive Logarithmic Increase Congestion Control Algorithm for Satellite Networks

This paper presents a new algorithm called the adaptive logarithmic increase and adaptive decrease algorithm (A-LIAD), which mainly addresses the Round-Trip Time (RTT) fairness problem in satellite networks with a very high propagation delay as an alternative to the current TCP congestion control algorithm. We defined a new increasing function in the fashion of a logarithm depending on the increasing factor α, which is different from the other logarithmic increase algorithm adopting a fixed value of α = 2 leading to a binary increase. In A-LIAD, the α value is derived in the RTT function through the analysis. With the modification of the increasing function applied for the congestion avoidance phase, a hybrid scheme is also presented for the slow start phase. From this hybrid scheme, we can avoid an overshooting problem during a slow start phase even without a SACK option. To verify the feasibility of the algorithm for deployment in a high-speed and long-distance network, several aspects are evaluated through an NS-2 simulation. We performed simulations for intra- and inter-fairness as well as utilization in different conditions of varying RTT, bandwidth, and PER. From these simulations, we showed that although A-LIAD is not the best in all aspects, it provides a competitive performance in almost all aspects, especially in the start-up and packet loss impact, and thus can be an alternative TCP congestion control algorithm for high BDP networks including a satellite network.

Design and Performance Evaluation of High Efficient TCP for HBDP Networks

While the legacy TCP is the most commonly used and reliable transport protocol in the Internet, it is not suitable for massive data transfers in high bandwidth delay product networks. To cope with this problem, we propose high efficient TCP congestion control mechanism that can provide efficient data transfer in HBDP networks. When there is some available bandwidth and it satisfies a certain condition, the congestion window grows rapidly. Otherwise, it maintains a linear growth of the congestion avoidance phase similar to the legacy TCP congestion avoidance algorithm. Based on the relationship of the current and minimum round trip time, the proposed method selects between the linear and rapid growth phases of the congestion window update during the congestion avoidance period. To prevent packet loss during the exponential growth phase, proposed method uses not only the end-to-end delay information, but also the estimated bandwidth of the bottleneck node.