1.2 Broadband Wireless Access Networks
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Deployment and Operational Aspects of Rural Broadband Wireless Access Networks Giacomo Bernardi I V N E R U S E I T H Y T O H F G E R D I N B U Doctor of Philosophy Institute of Computing Systems Architecture School of Informatics University of Edinburgh 2012 Abstract Broadband speeds, Internet literacy and digital technologies have been steadily evolv- ing over the last decade. Broadband infrastructure has become a key asset in today’s society, enabling innovation, driving economic efficiency and stimulating cultural in- clusion. However, populations living in remote and rural communities are unable to take advantage of these trends. Globally, a significant part of the world population is still deprived of basic access to the Internet. Broadband Wireless Access (BWA) networks are regarded as a viable solution for providing Internet access to populations living in rural regions. In recent years, Wireless Internet Service Providers (WISPs) and community organizations around the world proved that rural BWA networks can be an effective strategy and a profitable business. This research began by deploying a BWA network testbed, which also provides Internet access to several remote communities in the harsh environment of the Scot- tish Highlands and Islands. The experience of deploying and operating this network pointed out three unresolved research challenges that need to be addressed to ease the path towards widespread deployment of rural BWA networks, thereby bridging the rural-urban broadband divide. Below, our research contributions are outlined with respect to these challenges. Firstly, an effective planning paradigm for deploying BWA networks is proposed: incremental planning. Incremental planning allows to anticipate return of investment and to overcome the limited network infrastructure (e.g., backhaul fibre links) in ru- ral areas. I have developed a software tool called IncrEase and underlying network planning algorithms to consider a varied set of operational metrics to guide the oper- ator in identifying the regions that would benefit the most from a network upgrade, automatically suggesting the best long-term strategy to the network administrator. Second, we recognize that rural and community networks present additional is- sues for network management. As the Internet uplink is often the most expensive part of the operational expenses for such deployments, it is desirable to minimize overhead for network management. Also, unreliable connectivity between the network operation centre and the network being managed can render traditional centralized management approaches ineffective. Finally, the number of skilled personnel available to main- tain such networks is limited. I have developed a distributed network management iii platform called Stix for BWA networks, to make it easy to manage such networks for rural/community deployments and WISPs alike while keeping the network man- agement infrastructure scalable and flexible. Our approach is based on the notions of goal-oriented and in-network management: administrators graphically specify network management activities as workflows, which are run in the network on a distributed set of agents that cooperate in executing those workflows and storing management infor- mation. The Stix system was implemented on low-cost and small form-factor embed- ded boards and shown to have a low memory footprint. Third, the research focus moves to the problem of assessing broadband coverage and quality in a given geographic region. The outcome is BSense, a flexible frame- work that combines data provided by ISPs with measurements gathered by distributed software agents. The result is a census (presented as maps and tables) of the coverage and quality of broadband connections available in the region of interest. Such infor- mation can be exploited by ISPs to drive their growth, and by regulators and policy makers to get the true picture of broadband availability in the region and make in- formed decisions. In exchange for installing the multi-platform measurement software (that runs in the background) on their computers, users can get statistics about their Internet connection and those in their neighbourhood. Finally, the lessons learned through this research are summarised. The outcome is a set of suggestions about how the deployment and operation of rural BWA networks, including our own testbed, can be made more efficient by using the proper tools. The software systems presented in this thesis have been evaluated in lab settings and in real networks, and are available as open-source software. iv Acknowledgements I am very thankful to the communities around Loch Hourn, and in particular to some Tegola users: Finlay and Anna MacKenzie, Peter Carr, Peter Fletcher, Martin Davies, Ewen Ballantyne, Rick Rohde, Iain Wilson, Mick Simpson. Thanks to Martainn Domhnallach, for the precious assistance at the Sabhal Mor Ostaig campus, our In- ternet uplink. You all made me experience why the Highlands are so special. After all, Beinn Sgritheall is not that different from Monte Rosa. Thanks to Dmitry Rykovanov and Francesco Talamona for helping me implement the IncrEase system. For the work on the Stix system, I am grateful to Alex Macmillan and Matt Calder, who helped me code a software prototype, and to Robert Macgregor (University of Edinburgh) for his assistance in developing the StixControl board. For the BSense project, many thanks to Alessio Botta, Walter de Donato and An- tonio Pescape` (University of Naples ‘Federico II’) for the continuous support on their D-ITG tool. I am thankful to my supervisor Mahesh K. Marina, who taught me how to do research, guided me along this journey and painstakingly brought me back on track. I am heavily indebted to Peter and Annie Buneman, for the mixture of academic guidance, algorithmic tips, Highlands hiking and sailing, scaffolding hacking and warm meals they offered me. My admiration goes to the smart people at NGI SpA. Their example was inspiration for the topics discussed in this thesis. Everyday they demonstrate that the rural ISP business is profitable and socially useful. A toast with my flatmates, friends and colleagues Sofia Pediaditaki and Damon Fenacci (also co-author of several of my publications), who shared all the ups and downs of student life. I am grateful to my family and all my friends in Masnago. Thanks to Luca Polinelli and Davide Franzetti for being there when I needed. And to Rita Kosmidou, the best result of my academic research. This work was funded by the EPSRC, The University of Edinburgh Development Trust, and the School of Informatics IDEAlab. v Declaration I declare that this thesis was composed by myself, that the work contained herein is my own except where explicitly stated otherwise in the text, and that this work has not been submitted for any other degree or professional qualification except as specified. Some of the material used in this thesis has been published in the following papers. For publications with co-authors other than my advisors, their contribution is limited to helping with the implementation of the respective software tools. • Giacomo Bernardi, Peter Buneman and Mahesh K. Marina. Tegola Tiered Mesh Network Testbed in Rural Scotland. In the proceedings of the ACM Mobicom workshop on Wireless Networks and Systems for Developing Regions (WiNS- DR). September 2008. • Giacomo Bernardi, Francesco Talamona, Dmitry Rykovanov, Mahesh K. Ma- rina. IncrEase: A Tool for Incremental Planning of Rural Fixed Broadband Wireless Access Networks. In the proceedings of the IEEE GLOBECOM work- shop on Rural Communications (RuralComm). December 2011. • Giacomo Bernardi, Matt Calder, Damon Fenacci, Alex Macmillan, and M. K. Marina. Stix: A Goal-Oriented Distributed Management System for Large-Scale Broadband Wireless Access Networks. In the proceedings of ACM Mobicom. September 2010. • Giacomo Bernardi, Damon Fenacci, Mahesh K. Marina and Dimitrios P. Pezaros. BSense: A Flexible and Open-Source Broadband Mapping Framework. In the proceedings of the International Conference on Networking. May 2012. (Giacomo Bernardi) vi In memory of Carlo and Stefano. vii Table of Contents 1 Introduction 1 1.1 BroadbandDivide............................ 1 1.2 Broadband Wireless Access Networks . 5 1.2.1 AccessTier........................... 8 1.2.2 BackhaulTier.......................... 9 1.3 ThesisStatement ............................ 10 1.3.1 Broadband Mapping . 10 1.3.2 Network Planning . 11 1.3.3 Network Management . 12 1.4 Thesis Contributions . 12 1.4.1 RuralWirelessTestbed . 12 1.4.2 Incremental Network Planning . 13 1.4.3 Network Management . 14 1.4.4 Broadband Mapping . 15 1.5 ThesisStructure............................