# Experimental Performance Analysis of Wi-SUN Channel Modelling Applied to Smart Grid Applications
## 2 AMI Architecture and Last-Mile Communication
Wi-SUN is a seamless connectivity LP-WAN standard for smart utility networks, which amends Zigbee (IEEE 802.15.4) to IEEE 802.15.4g [13] for the physical layer (PHY), and IEEE 802.15.4e [14] for the MAC layer. Wi-SUN includes additional specifications of the MAC layer, adaptation, network and transport layer protocols standardized by IEEE and IETF to support several smart utility applications, e.g., smart municipality, city infrastructure monitoring and management and many more IoT applications [14]. Wi-SUN is an IPv6 wireless mesh network with frequency hopping, and multi-hop networking that improves robustness, reliability due to high redundancy and good scalability. Data rate is up to 300 kbps with low link latency. Therefore, the Wi-SUN mesh network has a self-healing network connection and is interference resistant, which is an interesting choice for studying in this article. With the rising interest in dependable wireless communications for AMI applications, there are various studies [5; 6; 7; 13; 14; 15; 16] that have recently focused on IEEE 802.15.4g (Wi-SUN) in many regions and countries. China uses IEEE 802.15.4g with a Gaussian frequency shift keying (GFSK) at 470-510 MHz and 779-787 MHz. Europe uses IEEE 802.15.4g with GFSK at 863-870 MHz, and US and Japan use IEEE 802.15.4g with GFSK at 920-928 MHz [6]. Nevertheless, one of the most common challenges for the Wi-SUN mesh network is channel modelling, which is typically used in estimating the signal behavior, such as channel propagations (i.e., absorption, reflection, scattering and diffraction), interference (i.e., thermal noise and shared unlicensed bands) and dynamic environment (i.e., multi-path fading channel). The smart meter installation in Thailand is typically fixed on the utility pole situated along the side of the street. The optimal location of DCU installation could significantly enhance the reliability of AMI communication networks, especially the quality of service (QoS). Additionally, Thailand does not specify the frequency band or modulation types used for AMI application. However, the national broadcasting and telecommunications commission (NBTC) published the radio frequency utilization for the development of the smart grid in Thailand [17], which suggested using wireless networks on unlicensed bands (i.e., 433 MHz, 920-925 MHz and 2.4 GHz) or a licensed band (i.e., utility's license) in the urban and suburban areas, and use the mobile network for rural areas. The 433 MHz and 2.4 GHz unlicensed bands are reserved internationally for industrial, scientific and medical (ISM) purposes [18]. The 920-925 MHz unlicensed bands are reserved for IoT applications in Thailand [19]. On the unlicensed bands, the AMI last-mile communication will share the communication's resource with other IoT systems, which is a concern point for the IIoT. On the other hand, 443 and 448 MHz licensed bands for SG applications are individual; therefore, the level of interference is low. The frequency bands of the Wi-SUN network in Thailand by NBTC suggestion are presented in Table 1, which are used in this article experiment. Hence, the experimental performance analysis in multiple bands of Wi-SUN channel modelling is of interest in this article.