Modifying the TCP Acknowledgement Mechanism

Nowadays the Transmission Control Protocol (TCP) is omnipresent in the Internet. TCP conveys 90% of the Internet traffic from applications, such as web, email, file transfers and even multimedia traffic. In this book we develop methods and algorithms to improve the fundamental working of TCP: the clocking on data packets through the timely reception of acknowledgements (ACKs). We study two complementary aspects on data transmission: the control of the congestion of ACKs and the acceleration of the ACKs frequency. First, we describe in detail a mechanism, called ACK congestion control (ACK-CC), allowing TCP to deal with the impairments produced by the congestion of ACKs in bandwidth asymmetrical networks. Then, we evaluate the functioning of ACK-CC in both phases of the transmission, namely slow start and congestion avoidance. On the other hand, for the acceleration of the ACKs frequency (and thus the acceleration of the transmission) we assess the ACK division technique, through both simple mathematical modeling and simulation. In this book we also discuss the performance of TCP over WiMAX networks. We focus on the impact of the WiMAX MAC-layer asymmetry on TCP.