# An Assessment of Environmental RF Noise Due to IoT Deployment
## 8 Discussions of Results  
Figures 9 and 10 brought some aspects to interrogate; however, the discussions prioritized answering this paper's question: what is the influence of IoT emissions on the radio noise environment? One of the first observations was that the mean values at the distributions' centers were very close to each other through Tx0 to Tx10 in their respective groups (site and band). The density plots in Figure 9 confirm the elimination of the outliers, as there were no visible isolated values. Additionally, there were no observations of skewed  
Figure 10: Regression lines and scatter plots grouped per candidate sites and frequency bands.  
distributions indicating near-zero skewness values. These graphs marked interesting resemblances, especially in their respective frequency bands:  
* The 433 MHz patterns exhibited characteristics of a normal distribution with noticeable Gaussian bell-shaped curves. Of course, the mean values of each transmit rate, supposedly at the center of the distributions, showed different values; however, the graphs remained symmetrical and centered around their mean through Tx0 to Tx10. The distribution shapes within each candidate site demonstrate that the data carried minor differences in standard deviations and variances, although small.
* The 868 MHz distributions demonstrated some abnormalities. The MNC and MNS data showed flattened distributions at their respective Tx10 graphs, indicating negative kurtosis values; however, the same sites presented peaked distributions with lower transmit rates exhibiting positive and high kurtosis. DUT, GLM, and NGM showed quasi-normal distributions; however, DUT and GLM counted fewer samples in their Tx10 data.
* The 2400 MHz patterns also exhibited the same characteristics as the normal distributions; however, the data showed ripples.  
The slope of the regression lines in Figure 10 helped to easily visualize the impact of increasing the transmit rates, thus multiplying radio activities in environments. Out of 15 assessments, only 3 cases (20%) showed a decreasing trend. Twelve cases (80%) indicated an augmenting direction. The levels of radio noise power in the linear scale show minimal differences, with the rates of the RF activities increasing; however, these variations, though small, may have significant merit in the context of environmental radio noise.  
In a university environment, such as the DUT Steve Biko Campus, ambient radio noise increased as the rate of the RF activities increased, irrespective of the operating frequency. The minimum amplitude was 10.529603 mW, and the maximum was 10.541081 mW at 433 MHz. At 868 MHz, the minimum was 1003.463161 mW, and the maximum was 1003.604141 mW. At 2400 MHz, the minimum was 38.965016 mW, and the maximum was 38.995504 mW. In the GLM site, the ambient radio noise at 433 MHz decreased while the rate of the RF activities increased. The maximum was 2.845122 mW, and the minimum was 2.844545 mW; however, the trends were augmented for 868 MHz (minimum 82.883005 mW, maximum 82.922968 mW) and 2400 MHz (minimum 53.710115 mW, maximum 53.740330 mW). In a suburban area such as Montclair, the ambient radio noise increased as the rate of the RF activities increased through all the frequency bands, namely, at 433 MHz (minimum 2.804772 mW, maximum 2.807212 mW), 868 MHz (minimum 1031.475526 mW, maximum 1031.693036 mW), and 2400 MHz (minimum 53.710115 mW, maximum 53.740330 mW). In an urban area such as Morningside, the ambient radio noise increased with the RF activities at 433 MHz (minimum 2.846615 mW, maximum 2.924101 mW) and 868 MHz (minimum 325.305783 mW, maximum 325.350955 mW). The trend declined at 2400 MHz (maximum 70.211370 mW, minimum 70.200025 mW). In an industrial environment such as New Germany, the ambient radio noise was increased with the RF activities at 433 MHz (minimum 2.591371 mW, maximum 2.592906 mW) and 868 MHz (minimum 589.076361 mW, maximum 589.092486 mW); however, the trend declined at 2400 MHz (maximum 186.602416 mW, minimum 186.409612 mW).