Wireless Ad Hoc and Sensor Networks

326 Wireless Ad Hoc and Sensor Networksflows are chosen as 0.1, 0.075, 0.05, and 0.025, with 4 flows selecting eachof these weights. Observe that the sum of the weights is equal to one. Thefigure shows that the ADFS algorithm results in fair allocation of bandwidtheven when flows have been assigned different initial weights.Example 7.4.2: Random TopologiesnThe ADFS protocol is now simulated for scenarios with n nodes, and22flows where the weight of each flow is . In general, initial weights arenassigned based on user specified QoS. Figure 7.7, Figure 7.8, and Figure 7.9represent the throughput/weight (normalized weights) ratio vs. the flowsfor networks with 32, 64, and 128 nodes, respectively. Plots show thatADFS and DFS result in fair allocation of bandwidth compared to the802.11 MAC protocol. Moreover, it can be observed that, though ADFSand DFS give almost the same degree of fairness, ADFS renders 10 to 20%higher throughput compared to DFS, due to weight adaptation anddynamic backoff intervals.The results shown in Figure 7.10 are for a network with 32 nodes and16 flows. Packet sizes of 584, 328, 400, and 256 are used for different flows.It can be seen that ADFS achieves fair allocation of bandwidth, even whenpackets of different sizes were used. Figure 7.11 depicts the throughput/weight ratio for the flows having different initial weights. The initial450400350ADFSDFS802.11Throughput/weight (Kbps)3002502001501005005 10 15 20Flows25 30FIGURE 7.7Performance of ADFS with 32 nodes.