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Wireless Ad Hoc and Sensor Networks

Wireless Ad Hoc and Sensor Networks

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400 <strong>Wireless</strong> <strong>Ad</strong> <strong>Hoc</strong> <strong>and</strong> <strong>Sensor</strong> <strong>Networks</strong>0.70.6Delay vs network sizeaodvdsrbelloedsr0.5Delay (s)0.40.30.20.1040 60 80 100 120Number of nodes140 160FIGURE 8.28Average end-to-end delay with network size.According to Figure 8.28 <strong>and</strong> Figure 8.29, the average E2E delaysobserved using the OEDSR protocol are much smaller than the delaysincurred using AODV, DSR, <strong>and</strong> Bellman Ford protocols, because, in theproposed protocol, the E2E delay is considered explicitly in the link_cost_factor calculation. OEDSR ensures that the route renders smaller E2Edelays, whereas the Bellman Ford <strong>and</strong> the AODV create a route withhigher E2E delay. By contrast, the DSR has much lower E2E delay thanthe Bellman Ford <strong>and</strong> the AODV protocols. This is because the DSR usessource routing to determine the RNs. Initially, the entire route has to bedetermined prior to routing. However, the OEDSR performs better thanthe DSR, because unlike the DSR, which maintains the same route, theOEDSR changes its route dynamically to lower the E2E delay. Therefore,OEDSR is an on-dem<strong>and</strong> routing protocol.As observed in Figure 8.30 <strong>and</strong> Figure 8.31, Bellman Ford consumesmore energy, whereas AODV has a greater E2E delay. Therefore, theappropriate overall metric to compare the actual performance of the protocolswill be to take the product of the energy consumed <strong>and</strong> the averageE2E delay. Both the energy consumed <strong>and</strong> the average E2E delay have tobe minimized for an optimal routing path. Taking the product of thesetwo metrics helps in identifying the optimal route, <strong>and</strong> therefore it isconsidered as the overall metric in OEDR. By doing so, it is observed thatthe Bellman Ford routing protocol has the highest product. This is because

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