A Method for Correcting Minimum RTT of TCP Congestion Control in Mobile Networks

In mobile networks such as LTE and 3G, there is a problem in that the transmission control protocol (TCP) cannot sufficiently utilize network bandwidth and TCP throughput decreases. One cause of this degraded TCP throughput is the underestimation of minimum round trip time (RTT) in TCP congestion control algorithms. Handovers between mobile networks might increase propagation delay, so it is important to increase the minimum RTT appropriately. However, conventional methods cannot increase the minimum RTT because the minimum RTT is updated when a shorter RTT is observed. This causes many delay-based TCP variants to decrease the congestion window size, which in turn decreases TCP throughput. In this paper, we propose a method that revises the minimum RTT in mobile networks based on information available at the TCP sender node. Simulation results indicate that the proposed method can appropriately revise the minimum RTT.