Throughput optimization in single commodity multihop packet radio networks

Abstract

Abstract In this paper, we are interested in determining the maximum throughput that can be supported between a pair of nodes in a multihop packet radio network. To determine the maximum throughput between a pair of nodes, single commodity traffic is considered, that is, the only traffic in the network is that which is being transmitted from the source node to the destination node. We investigate two channel access protocols: perfect scheduling (spatial TDMA, link activation) and slotted ALOHA with the results of perfect scheduling serving as the upper bound of the maximum throughput achievable. For perfect scheduling, we show that the maximum throughput between a pair of nodes in a packet radio network is always 1 if there exist four or more independent paths between those two nodes. For the slotted ALOHA protocol, the optimization problem can be formulated as a nonlinear programming problem. We only consider the case where the flow from the source to destination is equally split among all the independent paths connecting them. For networks with three or more independent paths connecting the source and destination nodes, we are able to find a closed form expression for the maximum throughput and the optimum transmitting probabilities for each node. Comparison between the perfect scheduling and the slotted ALOHA channel access protocols is then made.