# Evaluation of IEEE802.15.4g for Environmental Observations
## 4 Analysis
### Urban Canyon Scenario
#### 4.3.2 RX at 779 m  
At this distance we approach to the limit of the radio link. As shown in Figure 12a, only radio settings with data rates \(\leq\) 50 kbps present PDR values over 60% for frames of 127 B. The PDR of the reference 2 FSK-50 is only 42%. 2 FSK-FEC-50 is the only non O-QPSK PHY with its PDR > 50%. This RX node is located at the limits of the coverage proportionated by the TX node. We can observe the PDR values in Figure 12b for packets of 2047 B. Only 2 FSK-FEC-50 has a PDR over 50%. Even OQPSK PHYs, with their higher sensitivity, do not have a PDR over 50%. At this distance and in these conditions, only short packets can deliver a good reliability of 80% with OQPSK-50. Figure 11: Urban Canyon, 540 m. Some high data rate radio settings have a good PDR, close to 100%, and some others suffer from interferences. This is expected in this type of scenarios so an agile MAC layer would be useful in order to overcome those interferences by either changing frequency or waiting for the availability of the medium. (**a**) PDR values with packets of 127 B. Overall, high reliability except for OFDM3-600 and OFDM4-300. Reference value, 98% PDR; (**b**) PDR values with 2047 B packets. Overall values are over 50%, with a few OFDM radio settings. Highest values with 2 FSK-FEC-100 and OFDM4-100, 95% PDR and 96% PDR. Reference value, 84% PDR; (**c**) Maximum amount of TX packets of 127 B under the 0.1% duty cycle regulation. OFDM1-800 can transmit up to 1485 packets, while the reference 158 packets. OFDM2-600 and OFDM2-800 can also transmit more than 1000 short packets; (**d**) Maximum amount of TX packets of 2047 B under the 0.1% duty cycle regulation. OFDM1-800 can send up to 132 packets, OFDM2-600 110 packets and the reference just 9 packets; (**e**) Average electric charge consumed per packet of 127 B sent. OFDM1-800 is the less consuming radio setting, with 184 uC per packet whilst 2 FSK-50 consumes 1900 uC; (**f**) Average electric charge consumed per packet of 2047 B sent. OFDM1-800 and OFDM2-600 are the more electric charge-efficient PHYs, consuming around 2.1 mC and 2.5 mC. 2 FSK-50 consumes around 33 mC. Figure 12c shows the maximum amount of 1287 B packets that can be sent within an hour under the 0.1% duty cycle regulation. Only OQPSK-50 outperforms the reference, with the possibility of sending up to 81 packets per hour against 70 packets of 2 FSK-50. For long packets, the maximum amount of packets per hour can be seen in Figure 12d. With a maximum of roughly 5 packets per hour, OQPSK-50 is the most convenient PHY. 2 FSK-FEC-50 can send up to just 3 full packets and 2 FSK-50 is incapable of get any packet across. Figure 12e shows the average electric charge consumed by the TX node in order to get a 127 B packet across with the different PHYs. 2 FSK-50 consumes 4.3 mC and OQPSK-50 consumes 3.7 mC. Any other PHY does not consume less electric charge than those two. Similarly but with long packets, we see the electric charge consumption in Figure 12f. The TX node needs 105 mC to get a packet across when using 2 FSK-FEC-50 and 60.7 mC with OQPSK-50. In this scenario and at this distance, low data rates and poor PDR make energetically expensive to get packets correctly transmitted. If compared with the values at 540 m, at 779 m it is consumed twice the electric charge (2 FSK-50 at 540 m consumes 32 mC vs. OQPSK-50 at 779 m with 60.7 mC). In this scenario, we can see results that are counterintuitive:  
For OFDM1-800 and OFDM2 PHYs at 406 m, the PDR is lower for low data rates (50 to 400 kbps) than for high data rates (600 and 800 kbps). In interference-and-obstacle-free scenarios, it should be the opposite since lower data rates PHYs have a higher sensitivity. This can be attributed to interference occurred at the moment of the experiment. This affirmation is backed by the fact that for the rest of the radio settings at this distance, the PDR values are above 90%, even for those PHYs with lower sensitivity. Same reasoning goes with OFDM2-400 and OFDM2-600 at 512 m.  
Short frames have worst PDR than long frames.