Deployment and operational aspects of rural broadband wireless access networks

摘要

Broadband speeds, Internet literacy and digital technologies have been steadily evolvingudover the last decade. Broadband infrastructure has become a key asset in today’sudsociety, enabling innovation, driving economic efficiency and stimulating cultural inclusion.udHowever, populations living in remote and rural communities are unable toudtake advantage of these trends. Globally, a significant part of the world population isudstill deprived of basic access to the Internet.udBroadband Wireless Access (BWA) networks are regarded as a viable solutionudfor providing Internet access to populations living in rural regions. In recent years,udWireless Internet Service Providers (WISPs) and community organizations around theudworld proved that rural BWA networks can be an effective strategy and a profitableudbusiness.udThis research began by deploying a BWA network testbed, which also providesudInternet access to several remote communities in the harsh environment of the ScottishudHighlands and Islands. The experience of deploying and operating this networkudpointed out three unresolved research challenges that need to be addressed to easeudthe path towards widespread deployment of rural BWA networks, thereby bridgingudthe rural-urban broadband divide. Below, our research contributions are outlined withudrespect to these challenges.udFirstly, an effective planning paradigm for deploying BWA networks is proposed:udincremental planning. Incremental planning allows to anticipate return of investmentudand to overcome the limited network infrastructure (e.g., backhaul fibre links) in ruraludareas. I have developed a software tool called IncrEase and underlying networkudplanning algorithms to consider a varied set of operational metrics to guide the operatorudin identifying the regions that would benefit the most from a network upgrade,udautomatically suggesting the best long-term strategy to the network administrator.udSecond, we recognize that rural and community networks present additional issuesudfor network management. As the Internet uplink is often the most expensive partudof the operational expenses for such deployments, it is desirable to minimize overheadudfor network management. Also, unreliable connectivity between the network operationudcentre and the network being managed can render traditional centralized managementudapproaches ineffective. Finally, the number of skilled personnel available to maintainudsuch networks is limited. I have developed a distributed network management platform called Stix for BWA networks, to make it easy to manage such networksudfor rural/community deployments and WISPs alike while keeping the network managementudinfrastructure scalable and flexible. Our approach is based on the notions ofudgoal-oriented and in-network management: administrators graphically specify networkudmanagement activities as workflows, which are run in the network on a distributed setudof agents that cooperate in executing those workflows and storing management information.udThe Stix system was implemented on low-cost and small form-factor embeddedudboards and shown to have a low memory footprint.udThird, the research focus moves to the problem of assessing broadband coverageudand quality in a given geographic region. The outcome is BSense, a flexible frameworkudthat combines data provided by ISPs with measurements gathered by distributedudsoftware agents. The result is a census (presented as maps and tables) of the coverageudand quality of broadband connections available in the region of interest. Such informationudcan be exploited by ISPs to drive their growth, and by regulators and policyudmakers to get the true picture of broadband availability in the region and make informeduddecisions. In exchange for installing the multi-platform measurement softwareud(that runs in the background) on their computers, users can get statistics about theirudInternet connection and those in their neighbourhood.udFinally, the lessons learned through this research are summarised. The outcome isuda set of suggestions about how the deployment and operation of rural BWA networks,udincluding our own testbed, can be made more efficient by using the proper tools. Theudsoftware systems presented in this thesis have been evaluated in lab settings and in realudnetworks, and are available as open-source software.