We consider a multi-hop wireless mesh network composed by routers which route traffic to the Internet through several gateway. In such network, a bottleneck phenomenon limits the performances around the gateways, the network capacity does not scale with its size. In this work, we propose a traffic scheduling strategy around the gateways in a 802.11-based wireless mesh network. We distinguish two kinds of nodes according to their location in the network and the medium sharing strategy used: those located within k-hop of the gateway run a TDMA medium access protocol while the nodes further run a CSMA/CA MAC layer. We investigate on the impact of the size of the TDMA area on the network capacity when an optimal scheduling is implemented. Through extensive simulations, it is shown that network capacity, fairness and packet loss rate are improved by our approach.