End-to-End Modelling and Simulation of NLOS Sub-6 GHz Backhaul via Diffraction for Internet Connectivity of Rural Areas

Abstract

Many rural and remote areas around the world still lack access to the Internet due to the high deployment and maintenance costs, the lack of infrastructure, and the low income compared to urban regions. Therefore, cost-effective wireless backhaul links are required to connect these areas to the Internet core network. A wireless non-line-of-sight (NLOS) backhaul via diffraction in rural areas is a promising low-cost solution alternative to the traditional LOS backhaul. A reliable and cost-effective NLOS backhaul can be achieved if accurate propagation modelling and performance evaluation are performed before deployment. In this work, we first examine the accuracy of various terrain-based propagation models in predicting diffraction in different rural sites at unlicensed 5.8 GHz band. Although the classic irregular terrain model (ITM) is widely implemented in many radio frequency (RF) design software, we find that it overestimates the actual diffraction loss over small diffraction angles with an average error of −24 dB and RMSE value of 23 dB. However, a less complex rounded-obstacle diffraction model shows very high prediction accuracy compared to measured data with a negligible average error of −0.01 dB and RMSE value of 2.7 dB. Further, we evaluate the feasibility of an end-to-end NLOS backhaul link via simulation based on the IEEE 802.11ac standard using the practical characteristics of commercial RF equipment. The link performance is evaluated via end-to-end simulation in terms of the achieved throughput and the packet error rate (PER) over various antenna heights, modulation, and coding (MCS) schemes, and channel bandwidths. The results show that an NLOS backhaul at a distance of 11 km is viable with a throughput of 100–175 Mbps and PER of 0-0.1.

Keywords

• Backhaul
• diffraction
• microwave
• non-line-of-sight
• path loss
• rural areas