Performance evaluation of wireless multihop ad hoc networks using IEEE 802.11 DCF protocol

There has been a growing interest in multihop wireless ad hoc networks in recent years. Previous studies have shown that, in a wireless multihop network using the slotted ALOHA as the medium access control mechanism, the maximum throughput can be achieved if the number of neighbors is six to eight. We show that, when using the IEEE 802.11 DCF protocol in a wireless ad hoc network, the maximum end-to-end goodput is achieved when all nodes are within transmission range of each other. The main reason is that the channel spatial reuse factor gained from the multihop network does not match the increase in additional transmission hops that a packet needs to travel in a multihop network. For a multihop network, its MAC frame delivery capacity is approximately fixed at a value dependent on its spatial reuse factor. If the offered load increases, less capacity will be spent on delivering packets that eventually reach their destinations and hence resulting in lower end-to-end goodput.