Non-disjoint Flows

We now consider the case when the flows in the network are not disjoint - nodes participate as both sources and sinks, and in multiple flows. This scenario stresses SSCH's ability to efficiently support sharing among simultaneous flows that have a common endpoint. Each node in the network starts a maximum rate UDP flow with one other randomly chosen node in the network. We vary the number of nodes (and thus flows) from 2 to 20. As in the previous experiment, all nodes are within communication range of each other. We present the per-flow and system throughput for SSCH and IEEE 802.11a in Figures 11 and 12 respectively. The curves are not monotonic because variation in the random choices leads to some receivers being recipients in multiple flows (and hence bottlenecks). This lack of monotonicity persisted even after averaging over 5 simulation runs. As in the disjoint flow experiment, SSCH performs slightly worse in the case of a single flow, but much better in the case of a large number of flows.

Figure 11: Non-disjoint Flows: The average throughput of each flow on increasing the number of flows. There is a flow from every node in the network.

Figure 12: Non-disjoint Flows: The system throughput on increasing the number of flows. There is a flow from every node in the network.