## 6 Performance Evaluation
### Evaluating Management Efficiency  
#### 6.7.1 Performance During Node Joining  
In this section we evaluate the procedure of node joining in D-MSR as well as in WirelessHART, in terms of delay and overhead. We group the nodes based on their distance from the gateway into six categories in our evaluation. In D-MSR, the joining delay for each node at different hop distances in phase 1-3 (_i.e._, from the moment the node is started up till the node finds its path toward the gateway and the other devices) is the same. This is because most of the communications in phase 1-3 occur locally and do not depend on the hop distance of the node from the gateway. However, in Phase-4 as the hop distance increases, the delay in reserving the management resources increases as well. This is caused by the fact that in Phase-4, each node needs to reserve the management resources along the path towards the gateway and conversely. As the hop distance increases, the reservation procedure takes more time.  
To compare our node joining procedure with that of WirelessHART, we consider the total delay and overhead during Phases 1-4 in D-MSR. This is because in WirelessHART, the nodes that have sent the join request to the network manager, must wait to receive the activation command from the network manager after all the necessary network management resources (such as graphs and communication links) have been configured and reserved along the path. The joining procedure in WirelessHART therefore consists of forwarding the join request towards the network manager,  
\begin{table}
\begin{tabular}{c|c|c c} \hline \hline  & **Item** & **WirelessHART** & **D-MSR** \\ \hline \multirow{4}{*}{Static environment} & Network management energy & 38.77 J & 40.70 J \\ \cline{2-4}  & Application traffic energy & 52.84 J & 42.71 J \\ \cline{2-4}  & Total Energy (without idle) & 91.61 J & 83.41 J \\ \cline{2-4}  & Idle listening Energy & 51.48 J & 31.34 J \\ \hline \multirow{4}{*}{Dynamic environment (Link failures)} & Network maintenance energy & 3 Links & 0.717 J & 0.261 J \\ \cline{1-1} \cline{2-4}  & & 6 Links & 1.177 J & 0.435 J \\ \cline{1-1} \cline{2-4}  & Energy & 9 Links & 1.421 J & 0.560 J \\ \hline \hline \end{tabular}
\end{table}
Table 8: Energy-consumption in the network (in 1,000 s) during normal operation.  
allocating the required management resources for all the nodes along the path, and finally forwarding the activation command towards the new device.  
Figure 30 displays, the delay in nodes' joining and the number of required communications (number of messages sent) for node joining in the case of different hop distance categories. It is noticeable that the increase in hop distance results in more delay, and in a larger number of communications for joining the nodes. They do so for both D-SAR and WirelessHART.  
Figure 30 indicates that there exist considerable difference in the delay and number of required communications in node's joining between D-MSR and WirelessHART. It shows that the distributed scheme can perform far better in large-scale networks. It implies that D-MSR performs better in those scenarios in which the node joins and leaves the network frequently.