# A Resource Oriented Route Selection Framework Using Contextual Information Based on Fuzzy Logic
## 5 Performance Evaluation and Results
### Performance with Different Network Size  
In this section, we investigate the scalability of the proposed objective function at varying network size in a fixed network area. We constructed different network topologies with the number of nodes varying from 25 to 115. The impact of the topology variation is analyzed while considering the various aspects of LLN. To this end, we consider that all of the nodes in the network generate source traffic with a rate of 120 ppm. Besides, the traffic generation rate follows Poisson function. We keep other simulation parameters the same, as in Section 5.1. Figure 14a-d show various performance metrics of COOF and other OFs under different network size. Figure 12: Average end-to-end delay with respect to different inter packet interval. Figure 13: Average energy consumption with respect to different inter packet interval. As shown in Figure 14a, the packet loss ratio of all objective function increases with the network size. The packet loss ratio of OF0 and MRHOF is relatively high, as compared to others, it is because of the routing metric used during parent selection. Under our proposed OF, queue fluctuation at each node is considered to be a routing metric during path selection. Thus, the packet loss rate significantly reduces in COOF than default OFs. In contrast, SCAOF, MRHOF, and OF0 are unable to be aware of backlog packets at the node's buffer. As a result, a node may select preferred parent that is suffering from buffer overflow. As the network size increases, the packet loss tendency becomes more severe. In this situation, SCA-OF, MRHOF, and OF0 experience 16%, 22%, and 28%, respectively, whereas the COOF is less than 15%. The experimental results show that the composite metric scenario yields better results in the packet loss rate than the default RPL OFs. Figure 14b shows the packet receiving ratio in terms of different network size. As the size of the network grows, the proposed OF explores more routing paths to deliver data successfully to the root. As a result, COOF improves the aggregate throughput as compared to others. With the increased network size, the packet receiving ratio is decreasing for all the OFs. However, COOF achieves higher PRR than others. When the network size is 25 and 115, the PRR of COOF is about 91.4% and 82.6%, respectively. Whereas, the PRR of SCA-OF, MRHOF, and OF0 is about 88.4% and 76.3%, and 83.7% and 67.1%, 78.4%, and 59.2%, respectively. The reason behind the higher PRR in COOF is that it uses multiple metrics for route selection to respond to the network dynamicity. Besides, COOF takes into account the network resource utilization effectively. We evaluated the aggregated throughput for different network size. It is the total number of data bytes received by the root node. As shown in Figure 14c, the proposed OF leads to more throughput as compared to all others. The result shows that with the increasing of the network size, the throughput under all OFs increases. However, the variation is observed when the network size is different. As compared to default RPL OFs, SCA-OF and COOF both ensure higher throughput. This show that both metric composition based OF can perform effectively. When the number of node is high, i.e.,  
Figure 14: The impact of the network size variation on different performance metrics; (**a**) packet loss ratio, (**b**) packet receiving ratio, (**c**) aggregate throughput, and (**d**) end-to-end delay in milliseconds. 110, COOF achieves about 9.95% more throughput than SCA-OF and 39.6% than OF0. On the other hand, SCA-OF achieves about 20% more throughput than MRHOF. This is because both OFs combine multiple metrics for efficient route selection towards the root. Figure 14d shows that the end-to-end delay linearly increases as the network size increases for each of the OFs. However, COOF achieves the lowest end-to-end delay as compared to others. Besides, the delay variations in COOF with respect to increased network size are also more subtle than other OFs.