Mitigating the exposed node problem in IEEE 802.11 ad hoc networks

The enhancements to the IEEE 802.11 DCF MAC protocol which enable nodes to identify themselves as exposed nodes and to opportunistically schedule concurrent transmissions whenever possible, thereby improving utilization and mitigating the exposed node problem are described. The algorithm makes minimal changes to the IEEE 802.11 MAC protocol. It does not require the introduction of new frame types or changes to existing frame formats. We show, using simulations in GloMoSim, that it provides significant improvement in throughput.