## 4 Performance Analysis of QoS Metrics
### Evaluation of PDR for the Transmission Power Level (\(P_{\text{Trans}}\)) and Energy Consumption
#### 4.1.1 PDR Performance at Different \(\text{P}_{\text{Trans}}\)  
The packet delivery ratio can be represented by Equation (2), which signifies what percentage of the sent data packet is received at the other end, a vital metric in WSN. If the PDR is bad, the network is prone to losing important data and it also increases the number of retransmissions, which eventually increases the power consumption, network traffic, and data overhead. Moreover, some IoT applications in medical sector, and industry demand higher reliability where PDR is a very crucial parameter as it also signifies the reliability of the communication [51]. For the indoor scenario, the PDR is measured by  
Figure 4: Location of the coordinator end nodes in the indoor lab environment.  
placing the coordinator at C\({}_{1}\) and end nodes at E\({}_{25}\), E\({}_{30}\), E\({}_{35}\), and E\({}_{40}\), at a distance of 25, 30, 35, and 40 m from the coordinator, respectively, as presented in Figure 4. Moreover, 1000 data packets are sent from the coordinator to the end nodes at each location and from the number of received packets, PDR has been calculated. To equalize the effect of interference of other 2.4 GHz wireless technologies, three different tests at different times of the day have been carried out with the same setup and the mean of these three tests is taken into consideration. The transmission power is kept unchanged throughout the experiment and the whole process is repeated for each transmission power level, at 1, 3, and 5 dBm. For the test in the outdoor scenario, the coordinator node is placed in an open parking lot and end nodes around it with direct LoS where the interference is also minimum. Figure 5 presents the variation of PDR at different distances with three different transmission power levels.  
\[\text{PDR}=\frac{\text{Total packet received}}{\text{Total packet sent}} \tag{2}\]  
With 1 dBm, at 30 m of transmission distance, the PDR decreased to 96% and 97%, respectively, for indoor and outdoor scenarios, which are still quite reliable. The PDR with 3 dBm starts decreasing after 30 m and reaches 98% at 35 m with the indoor scenario whereas it still performs with 100% PDR in the outdoor. So, up to a transmission distance of 35 m, transmission with all the P\({}_{\text{Trans}}\) perform reliably. However, the PDR performances degrade drastically at 40 m in the indoor scenario for the transmissions of all the power levels which are 94%, 86%, and 50% for 5, 3, and 1 dBm, respectively. For the outdoor scenario, the PDR performances did not degrade so drastically, 96% and 75% with P\({}_{\text{Trans}}\) of 3 and 1 dBm, respectively, whereas the transmission with 5 dBm still performs with 100% PDR at a transmission distance of 40 m even. It is evident from the analysis that the decrease of the PDR at 3 dBm is not as drastic as at 1 dBm. The transmission link with 1 dBm becomes quite unreliable at 40 m for both indoor and outdoor scenarios whereas for 5 and 3 dBm it remains reasonably reliable with decent PDR indoor and performs with even better PDR outdoor. To find an optimized P\({}_{\text{Trans}}\) level with decent PDR and energy consumption, and extensive current and energy consumption analysis is done. This would help to realize the trade-offs between P\({}_{\text{Trans}}\), PDR, and energy consumption and to find an optimized P\({}_{\text{Trans}}\) where it can perform both reliably and energy efficiently.