Wireless Ad Hoc and Sensor Networks

408 Wireless Ad Hoc and Sensor Networksnodes, the number of collisions observed in the OEDSR is lower becauseof the fewer RNs used to route information. Congestion is mitigatedbecause of fewer numbers of nodes accessing the channel. For smallernetworks, OEDSR and DSR have almost the same number of collisions.This is because both these protocols use almost the same number of RNsto route information. But with an increase in network size, the DSR usesmore RNs to route information, while the OEDSR uses the same numberof RNs. This is because the OEDSR is an on-demand routing protocol andit uses E2E delay and distance to the BS from each node as the routingmetrics to minimize the number of RNs used. Consequently, the traffic inthe network is minimized and the numbers of collisions are minimized.Example 8.9.3: Comparison of OEDSR with OEDRStatic Case: Additional simulations were run for networks with 40, 50, 70,and 100 nodes randomly distributed. Parameters used for this scenarioare identical to the previous case.Figure 8.41 shows the comparison of energy consumed by the OEDSRand the OEDR, wherein the energy consumed is lower for the OEDSRthan the OEDR, because the OEDSR considers the distance of a node fromthe BS apart from the energy-delay metrics for calculating the link costfactor, as this decreases the number of RNs. On the other hand, the OEDRprotocol uses more RNs because the link cost factor is calculated based76.8Energy vs network sizeoedsroedr6.66.4Energy (mWhr)6.265.85.65.45.240 50 60 70 80 90Number of nodes100 110FIGURE 8.41Energy consumed with network size.