Wireless Ad Hoc and Sensor Networks

150 Wireless Ad Hoc and Sensor Networksand network utilization. Simulation results are provided to justify thetheoretical conclusions.4.2 Network ModelFigure 4.1a shows the popular parking lot network configuration forevaluating the proposed admission control, bandwidth estimation, andcongestion control schemes (Jain 1996). It can also be viewed as an endto-endloop, as shown in Figure 4.1b, if the traffic enters at the ingressnode/switch and leaves at the egress node passing through various networksor service providers and with very little information known aboutthe internal network state. The egress node, which also contains a limitedbuffer, sends a feedback signal at every measurement interval to theingress node via the network, with regard to the congestion. It is envisionedthat the proposed admission controller reside at each networkswitch fabric where the link bandwidth usage at the ingress node isestimated at every measurement interval. The most important step indetermining bandwidth usage and allocation is to estimate the networktraffic that is being accumulated at the ingress switch/node buffer in anintelligent manner, using its occupancy.S2Link capacityS3D3SW1D2SW2SW3S1D1(a)Provider 1Provider 2End-to-end flowsIIngress nodeEdge-to-edge loop(b)Provider 3EEgress nodeFIGURE 4.1(a) Parking lot configuration, (b) end-to-end network.