A cross-layer TCP enhancement in QoS-aware mobile ad hoc networks

With the increase of multimedia traffic over the Internet, current network protocols are largely concerned with the QoS requirements of delay-sensitive applications. In Mobile Ad-hoc Networks (MANETs), the majority of protocols developed to date provide QoS mechanisms by assigning high priority to delay-sensitive applications. While today’s Internet traffic is still dominated by TCP-based applications, the negative effects of the IEEE 802.11e service differentiation scheme on TCP performance in the presence of high priority traffic have not been adequately addressed in the literature. In this paper we first evaluate the performance of TCP in 802.11e MANETs when competing with high priority VoIP traffic. We then propose a novel TCP-friendly scheme, called IEDCA, to improve IEEE 802.11e EDCA mechanism. Our simulation-based performance study demonstrates that our proposed scheme IEDCA not only improves the performance of TCP significantly, it also facilitates the voice traffic transmission.