# Environmental Impacts on Hardware-Based Link Quality Estimators in Wireless Sensor Networks
## 3 Experimental Setup  
### Experimental Environments  
Experiments were conducted using TelosB, which is equipped with an IEEE 802.15.4 compliant radio chip CC2420 and an integrated planar inverted F-style antenna printed directly on the circuit board [31]. TelosB has been widely used in WSNs due to its advantages of small size, low power, \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Ref.**} & **RF Chip** & \multirow{2}{*}{**Experimental Environment**} & \multirow{2}{*}{**Parameters**} & \multirow{2}{*}{**Modeling Method**} \\  & **(Node Type)** & & & \\ \hline
[3] & N/A (Berkeley Mote) & indoor & _PRR_ & N/A \\
[4] & CC2420 (TelosB) & outdoor (garden) & _SNR_, _PRR_ & N/A \\  & & outdoor (500 kV substation), & & \\
[5] & CC2420 (TelosB) & indoor (underground transformer & _SNR_, _PRR_, RNP & N/A \\  & & vault and main power control & _SNR_, _PRR_, RNP & N/A \\
[6] & CC2550 (N/A) & indoor (industrial environment) & _SNR_, LQI, _PRR_ & N/A \\
[7] & CC2420 (TelosB) & indoor (corridor), outdoor & _PRR_ & N/A \\  & & (rooftop and playground) & _PRR_ & Pre-calibrated \\
[8] & CC2420 (N/A) & indoor (office) & _SNR_, _PRR_ & _SNR-PRR_ relationship \\
[9] & RFM TR1000 (Mica) & indoor (office), outdoor (park and parking lot) & Distance, _PRR_ & N/A \\
[10] & CC2420 (MicaZ, TelosB) & indoor (office), outdoor (dry lake) & _RSSI_, _PRR_ & N/A \\
[11] & CC2420 (Imote2) & outdoor (road) & Distance, _PRR_ & Fitting model \\  & outdoor (distribution substation, & & \\
[12] & CC2530 (N/A) & low-voltage transformer, & Distances, _SNR_, _RSSI_, _PRR_ & Theoretical model \\  & & residential area) & & \\
[15] & CC1101 (N/A) & single environment & _RSSI_, LQI, _PRR_ & N/A \\
[16] & CC2420 (TelosB) & outdoor & LQI, _PRR_ & Cubic model \\
[17] & CC2420 (N/A) & indoor (hadoop) & LQI, _PRR_ & Piecewise linear model \\
[18] & CC2420 (TelosB) & indoor (hadoratory) & _RSSI_, _PRR_ & Polynomial regression \\
[19] & MRF2440 (N/A) & indoor, outdoor (square and & _RSSI_, _PRR_ & Logistic regression \\
[20] & CC2530 (N/A) & indoor (office and a small home), & _SNR_, _RSSI_, LQI, & N/A \\  & TelosB) & outdoor (dry lake) & _PRR_ & N/A \\
[21] & CC2530 (N/A) & outdoor (smart grid) & _SNR_, _RSSI_, _PRR_ & Theoretical model \\
[23] & CC2420 (TelosB) & indoor (office), outdoor (park, & _SNR_, _PRR_ & Theoretical model \\  & square) & & & \\
[24] & AT86 RF231 (N/A) & outdoor (industrial) & _SNR_, _PRR_ & Theoretical model \\
[25] & CC2420 (N/A) & indoor (corridor), outdoor & _SNR_, LQI, _PRR_ & Logistic regression \\  & & (rooftop and playground) & _SNR_, _RSSI_, LQI, & Logistic regression \\
[26] & CC2420 (Tmote Sky) & indoor, outdoor & _SNR_, _RSSI_, LQI, & Logistic regression \\
[27] & CC2420 (Tmote Sky) & indoor (office building) & _SNR_, _RSSI_, LQI, & Logistic regression \\  & & _PRR_ & & Logistic regression \\
[28] & N/A & different environments & LQI, _PRR_ & N/A \\
[29] & CC2420 (TelosB) & indoor & _RSSI_ & N/A \\
[30] & CC2420 (TelosB) & outdoor (road) & _RSSI_, LQI, _PRR_ & N/A \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main features of existing studies. and ease of use. TelosB uses TinyOS 2.1 and is programmed with NesC language. TinyOS is an open-source operating system developed by Berkeley, which is specially designed for embedded WSNs. Several experimental environments were chosen, as shown in Figure 1. Among which, there were not only typical outdoor environments which have simple propagation channels and low external interferences but also a semi-enclosed environment which has complex propagation channel and high external interferences. The corridor was located in the first experimental building of the Chongqing University of Technology. Its length, width, and height were 106, 3.2, and 2.8 m, respectively. It was relatively clean and has almost no obstacles in the corridor. The runway and artificial lawn were located in the playground of the Chongqing University of Technology, which both have no obstacles in the line of sight (LOS).