PS: Path Sharing Scheme for AMI Networks

Traffic in Machine to Machine (M2M) communication is expected to contain a large number of constant but low data rate flows. The data rate may be much less than the link capacity. Yet interference between competing flows can lead to high loss. Medium access scheduling techniques are often not sufficient in such scenarios where the network is operating at high offered load with large number of contending transmitters. In such scenarios distributed medium access techniques such as 802.11 are unable to compute collision free schedules. Most on-demand network routing protocols react to increased packet loss due to collisions by triggering route repair events. This leads to a chain reaction of increased control overhead, and hence further increase in losses due to additional interference between routing messages and data flows. In a prior work we identified that the chain of packet loss and route repair events are results of inter-flow interference and this chain effect leads to low network utilization. In this paper, we address this issue by proposing PS, a route management scheme that computes shared routes so that interfering flows can be carried by a common network route. The objective of PS is to reduce inter-flow interference and in doing so minimal changes should be made to existing routing protocols. PS forces multiple traffic flows to share a common route and reduces dependence on link layer techniques for interference free scheduling. We have implemented PS on top of AODV and provided a simulation based comparison with the AODV protocol. We found that PS has a near constant routing overhead compared to AODV in which the routing overhead rises exponential when the number of traffic flows increases. This results in PS achieving 2x higher throughput compared to AODV with minimal impact on the end-to-end delay.