## 5 Performance Analysis
### Multiple Sources with Different Sink Position  
This section describes the effects with different position of multiple sources and a single sink for further analysis. The error group may vary according to the position of sources and a sink. The different number of sources and the position of a sink may slightly degrade the advantages of proposed RA due to the different shape of error group in MCP. In this experiment, we performed three simulations with different MCP including multiple sources and single sink. Figure 9 shows the deployment of different position of nodes and MCP. Basically, when the path between a source and a sink becomes longer, the lossy situation tends to frequently occur. For the simulation, multiple sources are placed at the edge of each topology with a different sink positions to maximize the effect of the lossy situation. Figure 9 shows each topology and the node deployment which defines the error group of MCP. We defined three topology based on the shape of each MCP to identify topologies: arrow type, cross type, and diamond type. Figure 9(a) shows the node deployment of arrow type that includes three sources and one sink placed at each corner. Figure 9(b) illustrates the topology of cross type which places four sources at each corner and one sink at the center. The third topology that includes three sources and one sink at the center of four each end edge as shown in Figure 9(c). Figure 10 shows the performance comparison in different MCP with the different position of multiple sources and a sink. According to our analysis, the arrow type of MCP shows the best performance. The second is the diamond type and the third is the cross type in order. In the Figure 10(a), the data delivery rate of both RA and OPP decreased smoothly as compared with the first simulation (one source and one sink). The increment of the number of source and different position of a sink influence the delivery rate of both algorithms. The topology with the arrow type of MCP showed the best delivery rate than others. Figure 9: The topology used in the simulation for different MCP including multiple sources with different sink position (i.e., error rate: 10%) **(a)** Arrow type, **(b)** Cross (X) type, **(c)** Diamond type. However, when the network is stable (error rate: 0%), all of OPP show better data delivery rates (almost 95%) than the case of RA (around 70%). The performance degradation of RA is resulted from interferences increased around a sink. When data arrives at the neighbors of a sink, a neighbor has to choose a next hop to send data to a sink. At the same time, if another neighbor tries to choose a route as the same way, the re-route scheme of the node is executed to avoid lossy situation. The packets generated by the re-route scheme may be additional overhead. For this reason, if a sink has insufficient candidate nodes, the interference may increase more in RA. Figure 10(b) shows the comparison of protocol overhead for each topology. All of OPP show larger protocol overhead than RA. Especially, when a sink is located at the corner (left-bottom), the interest flooding increased to recover lossy situation. Since the longer distance between a source and a sink enables the error probability to be high, protocol overhead is usually quite large in two topologies (arrow type and diamond type). The comparison of total number of packet is as shown in Figure 10(c). All of OPP show a large number of total packets resulting from generating many control packets in the algorithm. Oppositely,  
Figure 10: Performance comparison based on error rate in different topologies with multiple sources and different sink position (0%, 5%, 10%, 15%, 20%) (a) Packet delivery rate, (b) Protocol overhead, (c) Total number of packets. the number of total packets of RA is smaller than OPP. Compared to the first experiment (one source and one sink), the number of total packets of RA increased three times more due to the multiple sources.