# Neighbor Discovery for IPv6 over BLE Mesh Networks
## 5 Experiments  
In order to validate the proposed neighbor discovery protocol for 6 LoBLEmesh networks, a Revierbed modeling simulator was used to simulate and test the 6 LoBLEmesh ND according to BLE 5.0 protocol standard. Based on the specification of BLE mesh networks, we set the scanning events in continuous scanning mode, where the value of ScanWindow is equal to the ScanInterval. The advertising event adopts the random fallback mechanism, and the broadcast packet is sent with random waiting time. The start times of the advertisers and the scanner are independent. The start time of the scanner is chosen randomly between \([0,3T_{SIN}]\), and the advertisers are set randomly between \([0,T_{ADV}]\). The parameter settings are list in Table 4. In the simulation, there are \(N\) nodes in a 6 LoBLEmesh network, including nodes(friend nodes) and relay nodes. Meanwhile, a mesh gateway node is deployed as well. Figure 5 compares the analytical latency results and the simulation results for all nodes joining the network. The analytical results show the close patterns as the simulation results. Figure 5 shows that the number of relay nodes has a certain influence on the discovery delay of nodes in the network. First, up to 500 nodes are deployed in the network domain, using the 6 LoBLEmesh neighbor discovery protocol, and the overall average discovery latency can be maintained within 120 s. Next, if the number of relay nodes is sufficient, the discovery latency of the network can be greatly reduced. In particular, if the average number of connectable relay nodes is less than 25, the discovery delay in the network domain can be maintained within 60 s. Generally, an increase in the number of relay nodes that can be connected reduces the discovery latency of nodes in the network domain. Figure 6 shows the discovery probability for the different number of nodes \(N\) and the different number of relay nodes \(N_{r}\). In Figure 6, when \(N:N_{r}\) remained at 10:1, we can see that the discovery probability is close to 1. However, as the ratio of the number of nodes to the number of relay nodes increases, the discovery probability drops rapidly. When \(N\) increases from 100 to 500, the discovery probability drops to the lowest at the ratio of 15:1. For the case that \(N\) increases from 400 to 500, the discovery probability drops more sharply than the less crowded situation. When the ratio reaches to 11:1, the discovery probability declines to its lowest value. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline \(T_{ADV}\) & \(3s+\mu\) \\ \(\tau\) & 40 ms \\ \(\beta\) & 10 ms \\ \(\omega_{SW}\) & 8 s \\ \(T_{SIN}\) & 8 s \\ \(\tau_{AUX}\) & 3.764 ms \\ \(offset\) & 300 us \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The parameter settings in the simulation and the analysis. Figure 7 shows the Cumulative Density Function (CDF) of the discovery latency for different numbers of advertiser nodes. It can be seen that for fewer advertiser nodes, the discovery latency does not vary much between the best and worst cases. While even for 500 advertiser nodes, the proposed neighbor discovery process could promise the latency less than 35 s with a high probability. Figure 5: The average discovery latency respect to advertiser numbers. Figure 6: The discovery probability respect to advertiser numbers. Figure 7: Cumulative Density Function (CDF) of the discovery latency. To test the impact of the IPv6 address configuration mechanism on energy consumption, in the simulation, we set the number of relay nodes to 10, and also conducted neighbor discovery simulation for 50 advertiser nodes deployed in the network domain. The average energy consumption of a single node is tested under three conditions: no address configuration mechanism, static address configuration, and devices' private address configuration for nodes.