## 5 Experiments
### Setup  
The effectiveness of the proposed methodology has been tested in three indoor scenarios: a conference room, an office room and a small flat, with some details provided in Table 1. The tools used for the experiments are as follows:  
* Development kit case provided by Telit Wireless Solutions. This kit is made of five ZigBee radio boards that are based on the Texas Instruments CC2530 System on Chip with the Embedded Telit Z-One ZigBee-PRO Stack. The antennas are external dipoles characterized by an omnidirectional pattern. Four modules are used to create the network under analysis whereas the fifth works as the sniffer, for which a specific firmware has been developed to correctly capture all the packets on air. * The software used to inspect the packet content is Wireshark. To analyze the performance of the network from the Wireshark output and to conduct network discovery and commissioning, a specific tool has been developed by Telit Wireless Solution in collaboration with our lab and namedSRManager Tool. In this experiment, this tool has been used to collect the RSSI values observed from the different nodes in the network. During the experiments we used the standard ZigBee channel number 14 in the 2.4 GHz ISM frequency band. For each scenario, the blind nodes (\(N_{B}=4\)) have been placed randomly and then switched on; then, the sniffer has been moved again randomly in ten positions (\(N_{A}=10\)) to perform the required sniffing session. The network nodes are identified by their network 16-bit address: 00-00, 95-4C, 1E-57, 28-1F. For each position, the sniffer captures the first 1,000 packets generated by each active node and exchanged in the PAN network. We firstly performed the campaign of RSSI measures by the sniffer; secondly, we applied the model of indoor propagation to estimate the distances; and thirdly, we used the approach discussed in Section 4 to estimate the physical link performance. Figures 5-7 show the locations of both the blind nodes and the sniffer for the three scenarios. Note that in these figures, the origin of the Euclidean space has been set to the first anchor position. Through the serial port, the sniffer was connected to a laptop running Wireshark together with the SRManager Tool. For each position, the sniffer captured around 1000 packets from which we extracted the RSSI values from the IEEE 802.15.4 packets. This value is a measure of the power of the received signal as measured by the receiving device. In our scenarios, the receiver is the sniffer and the transmitters are the blind nodes building the PAN. For each packet with the same source node address, we extracted the RSSI and computed the arithmetic average of all the resulting values. Indeed, these measurements are affected by the peaks caused by a multipath fading, since in the indoor scenario a small variation of the environment can significantly affect the signal strength. This process is replicated for each anchor position. Finally, we obtained ten sets of observations, each containing information about the average RSSI value between the anchor node and the blind nodes. Table 2 shows the average RSSI values for the three scenarios. \begin{table}
\begin{tabular}{|p{56.9 pt}|p{113.8 pt}|p{113.8 pt}|} \hline
**Scenario** & **Size** & **Description** & **Link type** \\ \hline Conference room & 6.3 m \(\times\) 5.4 m & The room includes 12 desks with around 40 chairs. The room was empty when making the measurements. & LOS \\ Office room & 4.5 m \(\times\) 9.5 m & The room includes 5 desks, 5 personal computers, and 4 people were working when making the measurements. & LOS \\ Small flat & around 85 \(m^{2}\) & The flat has 5 rooms (kitchen, living room, corridor and 2 bedrooms) with typical furniture & LOS/NLOS \\ \hline \end{tabular}
\end{table} 
Table 1: Environment of the experiments scenarios. Figure 5: Position of the blind nodes and anchors for the conference room experiments. Figure 6: Position of the blind nodes and anchors for the office. Figure 7: Position of the blind nodes and anchors for the flat.