Wireless multihop backhauls for rural areas: A preliminary study

RESEARCH ARTICLE Wireless multihop backhauls for rural areas: A preliminary study Zainab Zaidi1, Kun-chan Lan2* 1 Independent Researcher, London, United Kingdom, 2 Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan City, Taiwan * Abstract a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Zaidi Z, Lan K-c (2017) Wireless multihop backhauls for rural areas: A preliminary study. PLoS ONE 12(4): e0175358. https://doi.org/ 10.1371/journal.pone.0175358 Editor: Kim-Kwang Raymond Choo, University of Texas at San Antonio, UNITED STATES Rural areas have very low revenue potential. The major issue in providing low-cost broadband to rural areas is to provide reliable backhaul connections that spread over tens or even hundreds of miles, connecting villages to the nearest service provider. Along with aerial networks of Google and Facebook, there has been a considerable amount of research toward long-distance terrestrial WiFi links. As a comparison, WiFi routers are easier to be deployed and maintained by non-technical people from the local communities, whereas the aerial networks require professional support to operate. Moreover, they are still in the experimentation phase. However, the long distance WiFi links require high-gain directional antennas and very expensive tall towers for high data rates. On the other hand, multihop paths with stronger links may provide better data rates without the need of tall towers. In this paper, we evaluated the concept of using such multihop WiFi links for long backhaul connections. Our simulation results show that these networks can possibly be a cost-effective and practical solution for rural connectivity. These initial results can serve as a first step to understand the comprehensive feasibility of using multihop WiFi networks for backhaul connections in rural area. Received: September 15, 2016 Accepted: March 7, 2017 Published: April 12, 2017 Copyright: © 2017 Zaidi, Lan. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All data used in our simulations can be found in the URL below: https:// github.com/lenscsie/Rural-chain. Funding: The author(s) received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Introduction In the modern telecom era of low-cost and high-speed WiFi technology, plug-and-play type small cells, flexible and programmable software defined networks and functional virtualization, there exists huge opportunity for bridging digital divide which never existed before [1]. Although, the advancements are mostly driven by high-capacity demands in urban areas, but low-cost, flexible use, and hardware sharing possibilities of these equipment could be the much-awaited enablers for a practically realizable and economically feasible first generation of rural network technology. The major inhibitor for rural deployment is the return potential of the sparsely populated low-income communities. The usual distance that needs to be covered for providing backhaul connection, i.e., connecting remote villages to the nearest service provider, could be tens or hundreds of miles. According to [2], the revenue potential for a traditional wireless carrier in a least populated area of USA drops to $262 per square mile from $248,000 per square mile in a PLOS ONE | https://doi.org/10.1371/journal.pone.0175358 April 12, 2017 1 / 32 Wireless multihop backhauls for rural areas major urban center. When translated to low-income developing regions, the potential drops even further. Satellite, although provide global coverage, is also the most expensive approach, with the cost of 1 Mbits/s connectivity in Africa exceeding $3000/month [3]. Recent initiatives from Google (www.google.com/loon) and Facebook (www.internet.org) have started to look into exploiting the aerial space over the remote areas to provide connectivity. In aerial networks, a costly node/network could be made affordable as it serves a much larger area but economical network maintenance and providing always-on, reliable, and secure connectivity in wake of intermittent link/node failures are still big open challenges. Moreover, with 60% global population still on the other side of digital divide, it is a huge problem with no simple solution yet in sight. It is very important to explore possibilities and cheaper alternatives, specially those which can be managed and run by local communities. On the other hand, there has been a considerable amount of research directed towards long-distance WiFi links [3–6], and the practicality of this approach has been successfully demonstrated, with the current record being a 6 Mbits/s link over 384 Km in Venezuela. Such links require LoS (Line of Sight) for sufficient signal-strength; otherwise, signal attenuation in the 2.4-5 GHz range becomes too high beyond a few hundred meters [4]. To provide LoS, significant infrastructure investments in terms of antenna towers are required [4]. The tall towers are usually one or two orders of magnitude more expensive than the equivalent radio equipment, e.g., a 45 m tower costs around $5000 according to [4]. The use of high-gain directional antennas also considerably increases the cost. A detailed survey of different rural communication initiatives is given in Section Related Work. In this paper, we focus towards multihop relay networks rather than a single link to provide real-time backhaul connectivity over large distances. Our main motivation comes from the fact that multihop paths with smaller and stronger links with high capacity may provide better data rates than a longer and weaker link with low-rate modulation. With low cost hardware such deployment may also be economical and cost-effective. With plug-and-play type of nodes, the local manpower can be trained to perform day-to-day maintenance tasks, which reduces the cost and delays in maintenance and also creates opportunities for involvement of local community, a must for sustained success of such project according to [7]. Such networks can be deployed along existing roads, as shown in Fig 1. They would be easily accessible and can utilize the available utility poles and resources, e.g., power supply and maintenance logistics, to further reduce the cost. These networks can be used to provide connectivity to the commuters as well along with relaying backhaul traffic, although, this scenario is outside the scope of present paper and our analysis considers only the backhaul traffic for reliable delivery. Commuter traffic will provide significant interference and reduce the capacity of network for relaying backhaul data. As software defined networks with functional virtualization are becoming a re (...truncated)