# From Sensor Networks to Internet of Things. Bluetooth Low Energy, a Standard for This Evolution
## 7 Improving the CSR Mesh
### Individual Mesh Evaluation
#### 7.2.2 CSR Devices Retransmit Each Packet Once  
In this experiment, CSR devices were configured in a saving mode, retransmitting each received packet once, while Waspmote devices used both two available configurations in our mesh proposal: _Low Network Load_ (each packet is transmitted only once by Waspmote devices) and _High Network Load_ (each packet is transmitted three times by Waspmote devices). Tables 10 and 11 contain data relating to network traffic. Specifically, Table 10 shows the number of packets received by CSR devices, as well as the number of original packets received by the BLE server. As we can see, the highest number of packets is received by CSR2 and CSR3 devices (especially CSR2) for both configurations, due to sensor nodes placement (see Figure 14). Analysing each configuration, an important increase in the number of packets is observed for _High Network Load_ configuration (198% for the CSR devices, on average, compared to _Low Network Load_), although the number of packets received by the BLE server is increase only a 12.4%. Table 11 shows the number of packets sent by each sensor node. Although knowing the immediate destination node is not possible due to the broadcast topology, the number of packets received in the final destination node (BLE server) is showed. In this case, the number of received packets by BLE server is increased when the _High Network Load_ configuration is used, as we will analyse later. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Number of Packets Transmitted**} & \multicolumn{4}{c}{**Packets Received by**} \\ \cline{2-5}  & **CSR1** & **CSR2** & **CSR3** & **Server** \\ \hline
1 (Low Network Load) & 7172 & 11,481 & 9197 & 4814 \\ \hline
3 (High Network Load) & 15,628 & 20,480 & 18,395 & 5410 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Number of packets received by CSR devices and BLE server for each Waspmote device configuration in Individual Mesh with CSR devices retransmit each packet once. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sensor Nodes**} & \multicolumn{3}{c}{**Low Network Load**} & \multicolumn{3}{c}{**High Network Load**} \\ \cline{2-5}  & **Sent Packets** & **Packets Received by BLE Server** & **Sent Packets** & **Packets Received by BLE Server** \\ \hline W1 & 677 & 642 & 669 & 668 \\ \hline W2 & 668 & 624 & 695 & 695 \\ \hline W3 & 646 & 610 & 681 & 678 \\ \hline W4 & 632 & 590 & 670 & 669 \\ \hline W5 & 637 & 538 & 684 & 679 \\ \hline W6 & 660 & 611 & 682 & 675 \\ \hline W7 & 672 & 587 & 681 & 681 \\ \hline W8 & 654 & 612 & 669 & 665 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Number of packets sent by each sensor node and received by BLE server, for each Waspmote device configuration in Individual Mesh with CSR devices retransmit each packet once. As Figure 16 shows, the network PLR average was lower for these configurations, compared with the PLR average from CSR Mesh when CSR devices retransmit each packet once: 8.25% for _Low Network Load_ and 0.39% for _High Network Load_, compared with the 16.73% for CSR Mesh retransmitting each packet once. The PLR for _High Network Load_ is notable, specially for Industry 4.0 requirements. Table 12 shows the traffic network, measured in packets per second received in CSR devices. As seen in CSR Mesh experiment, when packets were retransmitted only once, 1.04 packets were received in each CSR device, on average, for two sensor devices. Using our mesh proposal, we achieved a 2.71 packets per second received by each CSR device, on average, for 8 sensor devices configured with a _Low Network Load_, which guarantees the network scalability. Moreover, to minimize the PLR is possible using _High Network Load_ configuration, although network traffic is slightly higher (5.19 on average for 8 sensor devices). In this experiment, our proposal achieved a lower PLR than CSR Mesh; although the network traffic was increased, given that there was a higher number of sensor devices.