Explicit-feedback-based congestion control for lossy and dynamic wireless networks

Recently explicit-feedback-based congestion control with the assistance of routers has been introduced to deal with the inefficiency problem of TCP in high bandwidth-delay product (BDP) wired networks. However, when applying this kind of congestion control to wireless networks, we encounter two challenges. One is how to probe the unknown bandwidth capacity of a wireless link which is required in calculating router feedback. The other is how to distinguish the two kinds of packet loss (bit-error loss and congestion loss) in wireless networks and react to each of them properly. In this paper we propose some practical and novel enhancements on explicit-feedbackbased congestion control for wireless environment and we have implemented these enhancements in a congestion control protocol called QFCP. Through ns-2 simulations we show that it can fairly allocate wireless bandwidth resource among competing flows under heterogeneous network conditions.