# Location-Aware Point-to-Point RPL in Indoor IR-UWB Networks
## 5 Performance Evaluation  
In this section, P2P-RPL, ER-RPL, and LA P2P-RPL are implemented on Cooja network simulator for Contiki operating system platform [29; 30]. LA P2P-RPL implementation is based on the modules of ContikiRPL library and P2P-RPL implementation on Contiki platform. The software architecture of Location-Aware P2P-RPL is shown in Figure 7.  
The radio channel features are based on Decawave DW1000 UWB device radio characteristics on the lossy environments, and the simulation studies are conducted with the IEEE 802.15.4 [29; 30]. In this paper, the network configuration is basically stationary for routing procedures just like in RPL and P2P-RPL operations. In basic simulation network configurations, 200 stationary nodes are randomly deployed in a 150 m \(\times\) 150 m network area while anchor nodes are deployed at every 75 m, and the average estimated localization error is 120 cm. Five mobile nodes are moving continuously with slow random walking speed and operate as leaf nodes without intermediate route forwarding features in route discovery procedures [27; 28]. In this simulation study, the source and the destination node pair is randomly selected for each traffic flow. We used the model of UWB frame transmission time and  
Figure 7: The software architecture of position-adaptive forwarding zone based P2P-RPL on Contiki OS. the parameter setting validated by [PERSON] et al. in the testbed experiments [31; 32]. The latency from initiating P2P route discovery by sending a P2P-DIO of 66 bytes to receiving the first P2P-DRO of 38 bytes takes much less than 1 s, which includes UWB packet transmission time and the time required for the P2P-DIOs to reach the destination node considering Trickle parameters. Other parameters are displayed in Table 1. A different random topology is generated and each data result is the average value from all simulation runs. The following metrics are adopted to evaluate the performance of the proposed protocol. 1. Routing control overhead refers to the total number of control messages for finding P2P routing path between the source node and the destination node. 2. Energy consumption refers to the total energy consumption for finding P2P routing path between the source node and the destination node. We only consider the energy consumption in transmitting and receiving states by using the first order radio model [33]. The parameters used in the first order radio model are shown in Table 1.
3. Average routing path finding success rate refers to the ratio of the successfully routing path finding number to the total number of the routing path finding attempts. 4. Average hop count refers to the average discovered P2P routing path hop length between the source node and the destination node. 5. Packet delivery ratio (PDR) refers to the ratio of the successfully received packet number on the destination node to the total generated packet number by the source node. Figures 8-10 show the performance results for the network configuration of 150 m \(\times\) 150 m with 200 nodes. Figure 8 shows that the routing control overhead for route discovery increases as the distance between the source node and the destination node increases. Even in the short range networking situations for P2P-RPL route discovery procedure, the route discovery forwarding packets are flooded through the whole network. Location-aware P2P-RPL reduces the unnecessary forwarding packets by using the location information of the source and the destination node. In LA P2P-RPL, if the distance between the source and the destination node is short, the route discovery forwarding zone is limited to a small area, which reduces the number of route discovery forwarding packets significantly. Figure 8 shows that LA P2P-RPL reduces the route discovery forwarding overhead significantly in short distance range.