Distributed Protocols for Scheduling and Rate Control to Achieve Max-Min Fairness in Wireless Mesh Networks

The goal in this paper is to develop comprehensive protocol support in all layers to provide max-min fairness for multihop flows in a wireless mesh network. Our approach has three parts. First, we estimate the max-min fair rate of all multihop flows in the network using a distributed protocol. This estimation uses the knowledge of the flow contention graph that the network nodes learn by exchanging local information. Second, the nodes enforce this rate by controlling the rate at which a flow is scheduled to the link layer. Third, a back pressure flow control is used to reduce the transmission rate of a flow if it has been exceeding its fair rate. Finally, we argue that the fair rate estimation can at best be approximated in an 802.11 based MAC protocol. Thus, to complement our fair rate estimation and scheduling procedures, we develop a virtual time based MAC protocol. We demonstrate via extensive simulations the benefit of all these approaches for ensuring fairness relative to the base case that uses 802.11 MAC and FIFO scheduling.