# Swarm-Intelligence-Centric Routing Algorithm for Wireless Sensor Networks
## 4 Performance Evaluation  
This section presents the results of the WSN simulations performed using Network Simulator-2 (NS-2), and compares them with those obtained using the proposed SICROA protocol, AODV, and dynamic source routing (DSR) routing protocols [39; 40; 41]. One hundred nodes were randomly distributed in a square region with 1000-m\({}^{2}\) area, and the results obtained were measured in accordance with the change in the number of nodes in the proposed protocol. The experiment was repeated 10 times, and the number of nodes was increased from 10 to 100 in increments of 10 during each iteration. The random waypoint (RWP) was used as the mobility model, and the performance change was examined in terms of mobility by changing the maximum speed from 5 to 30 m/s. During the 90-s simulation, the occurrence of data packets was observed every 0.25 s, and RREQ flooding occurred in intervals of 1, 2, and 3 s. ROUTE_TIMEOUT--i.e., the time for deleting the generated routing information--was set to 3 s, and the TTL value of all of the control packets was set to 20. To confirm the routing effect, they were only reflected in the results when the number of shortest-path hops between the origin and destination exceeded three. In addition, the TTL value was set large enough to ensure that RREQ and RREP remained flooded throughout the network during flooding for initial routing. The end-to-end delay in Figure 6 denotes the time required for a data packet to arrive successfully at its destination, and it represents the length of the path used for data transmission. The proposed method demonstrates the lower delay performance compared with the existing AODV and DSR techniques. In addition, a lower delay performance is observed corresponding to a shorter flooding period at the beginning of the destination, owing to frequent updating of the new path. In general, for all of the routing protocols, the delay increases with the increase in mobility. However, in this study, the end-to-end delay of all of the routing protocols was reduced owing to the consideration of only successfully delivered data packets for delay-performance evaluation, and the new shortest path was found during path disconnection. Figure 5: Route table entry when using SICROA. The packet delivery ratio in Figure 7 can be defined as the ratio of data packets arriving at the destination to the total number of data packets originating from the source. Thus, the packet delivery ratio is directly affected by the number of disconnections, because each node immediately discards the data packet, which needs to be delivered to the destination without resending it, when the path is disconnected. Therefore, the performance of the proposed method was observed to have greatly improved in terms of the packet delivery ratio. Figure 8 shows the trend concerning changes in the survival rate of nodes with an increase in the node count until the end of the simulation. The observed trends correspond to the formation of a large network. As can be confirmed, SICROA demonstrates a higher survival rate, owing to its consideration of residual energy, which is not considered by other routing protocols. Upon selection of the network path, both the transmission and reception of the control packets is reduced, which in turn reduces energy consumption. Figure 6: Latency measurement with respect to node count. Figure 7: Packet delivery ratio with respect to number of nodes. Based on the observed trends concerning the simulation factors, as described in Figures 6-8, the proposed SICROA routing protocol clearly outperforms AODV and DSR. Because the transmitting node exchanges paths through the researching path prior to the occurrence of node failure and link damage, no data or link loss occurs. Additionally, the packet delivery rate in SICROA exceeds those observed when using DSR and AODV. In other words, because the transmitting node continues to initiate path discovery prior to packet transmission, the disconnection of all paths can be avoided.