UC Berkeley UC Berkeley Electronic Theses and Dissertations Title Towards Scalable Community Networks Permalink https://escholarship.org/uc/item/1zr87965 Author Hasan, Shaddi Publication Date 2019 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California Towards Scalable Community Networks by Shaddi Husein Hasan A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Computer Science in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Eric Brewer, Chair Associate Professor Joshua Blumenstock Professor Scott Shenker Professor Anant Sahai Spring 2019 Towards Scalable Community Networks Copyright 2019 by Shaddi Husein Hasan 1 Abstract Towards Scalable Community Networks by Shaddi Husein Hasan Doctor of Philosophy in Computer Science University of California, Berkeley Professor Eric Brewer, Chair Over 400 million people live without access to basic communication services, largely in rural areas. Community-based networks, and particularly community cellular networks, can sustainably support services even in these extremely rural areas where traditional commercial network operators cannot. However, community cellular networks face a variety of technical, business, and regulatory challenges that hamper their proliferation. In this thesis, we aim to develop approaches to enable scale within and across community cellular networks. Through a mixed-methods study of more than 80 rural wireless Internet service providers, a related class of network operators, we identify key scaling challenges rural network operators face. We next present two approaches for addressing these challenges in the context of community cellular networks. The first, GSM Whitespaces, demonstrates that rural community cellular networks can safely share spectrum in bands occupied by incumbent mobile network operators, removing a key barrier to independent operation. The second, CCM, shows how community networks and incumbent mobile network operators can cooperate to share resources to extend service. We will explore each of these approaches through practical systems and longitudinal deployments of community cellular networks in Southeast Asia that provide service to thousands of rural people. i For the people doing the work to make the community networking vision a reality. ii Contents Contents ii List of Figures iv List of Tablesv 1 Introduction1 1.1 Summary of Results ............................... 6 1.2 Dissertation Outline ............................... 7 2 Understanding the Rural Challenge9 2.1 Background.................................... 9 2.2 The Challenges of Scaling WISPs........................ 11 2.3 Methodology ................................... 12 2.4 WISP Demographics............................... 13 2.5 Operational Challenges.............................. 13 2.6 The Role of Automation............................. 20 2.7 Conclusions.................................... 22 3 Shared Spectrum for Community Cellular 24 3.1 A Brief History of Spectrum Regulation .................... 26 3.2 Dynamic Spectrum for Community Cellular .................. 29 3.3 Community Cellular Networks.......................... 31 3.4 GSM Whitespaces................................. 33 3.5 Nomadic GSM .................................. 35 3.6 Opportunities, Risks, and Incentives ...................... 39 3.7 Evaluation and Deployment ........................... 43 3.8 Discussion..................................... 52 3.9 Conclusion..................................... 54 4 Scaling Community Cellular Networks with CCM 56 4.1 Related Work................................... 57 4.2 Design Goals ................................... 59 iii 4.3 System Design................................... 60 4.4 Deployments.................................... 69 4.5 Evaluation..................................... 74 4.6 Discussion..................................... 85 4.7 Conclusion..................................... 87 5 Conclusion 89 5.1 Open Challenges ................................. 90 5.2 Lessons Learned and Closing Thoughts..................... 92 Bibliography 110 iv List of Figures 2.1 Network outage frequency by failure mode in rural WISPs............. 18 3.1 Overview of Nomadic GSM.............................. 30 3.2 The hidden node problem............................... 30 3.3 Indonesian cellular coverage as of 2013 across all carriers.............. 34 3.4 Layout of indoor test environment for Nomadic GSM................ 45 3.5 Handset uplink spectrum usage during a call. ................... 46 3.6 Spectrum usage during simulated arrival of a primary into the secondary's service area........................................... 47 3.7 Measurement report interarrival times from Papua deployment. ......... 49 3.8 Measurement report time series from Papua deployment.............. 50 3.9 Spectrum usage and scanning results from Papua deployment........... 51 4.1 CCM high level architecture.............................. 60 4.2 CCM Client architecture. .............................. 62 4.3 Illustrative CCM Client hardware components. .................. 63 4.4 CCM web user interface................................ 65 4.5 Typical University of Philippines site installation.................. 69 4.6 University of Philippines site deployments...................... 71 4.7 Aerial view of Dilasag site............................... 72 4.8 Globe proof-of-concept sites.............................. 72 4.9 Map of sites in Phillipines deployment........................ 75 4.10 Monthly active users by site type........................... 80 4.11 Site uptime by site type................................ 81 4.12 Distribution of CCM checkin sizes. ......................... 82 4.13 The infographic for the local repair service...................... 83 v List of Tables 2.2 WISP network management practices and upstream ISP redundancy. 20 3.1 A summary of wide-band spectrum occupancy studies............... 25 3.2 Bandplan for the GSM900 band in Indonesia. ................... 33 3.3 Parameters used for Nomadic GSM.......................... 44 3.4 Results of primary and secondary coexistence tests................. 48 3.5 Service utilization before and after Nomadic GSM in Papua deployment..... 50 4.1 Philippines deployment site launch dates....................... 76 4.2 Example site cost breakdown for a Globe site.................... 77 4.3 Example site cost breakdown for a University of the Philippines site. 78 4.4 Example monthly operating expense for University of Philippines site. 79 4.5 Volume of usage by service type. .......................... 79 4.6 Site outage duration by cause in University of Philippines sites. ......... 85 A.1 Q1. What are your roles in your organization?................... 94 A.2 Q2. Which of the following describe where your organization provides service? . 95 A.3 Q3. How many people work for your organization? ................ 95 A.4 Q4. How many subscribers does your network have? ............... 95 A.5 Q5. How many network devices are used in the backhaul portion of your wireless network?........................................ 96 A.6 Q6. How many network devices are used in the client-facing portion of your network?........................................ 97 A.7 Q7. If your organization offers other services besides fixed wireless broadband, please list them here.................................. 98 A.8 Q8. How many upstream providers do you have? ................. 99 A.9 Q9. What is the total bandwidth commitment to your upstream providers? . 99 A.10 Q10. What is the total bandwidth commitment from your subscribers to you? . 99 A.11 Q11. What is the typical peak usage you see on your network? . 100 A.12 Q12. Which of the following do you provide to your customers? . 100 A.13 Q13. How large is your total public IP address allocation? . 100 A.14 Q14. How much does your organization spend per month on: . 101 vi A.15 Q15. Which best describes how often your network experience faults due to each of the following:.................................... 102 A.16 Q16. How much downtime per fault event does your network experience as a result of:........................................ 103 A.17 Q17. Does your organization perform any of the following traffic engineering practices? ....................................... 104 A.18 Q18. Describe any other traffic engineering your organization performs. 105 A.19 Q19. What is the biggest challenge your organization faces that you want a solution to?...................................... 106 A.20 Q20. Anything else you want to share about your network and organization? . 108 vii Acknowledgments I have been told that a dissertation is an individual work, but in putting this one together I have never felt alone: I am lucky to have had a wonderful and supportive community of collaborators, friends, and family accompanying me throughout this journey. I thank Eric Brewer, my advisor, for his unyielding optimism about my work and enthu- siastic mentorship throughout my time at Berkeley. I am also grateful to Scott Shenker for his steadfast support and encouragement throughout the different phases of my time in grad- uate school; Anant Sahai for his clear insights and fruitful interdisciplinary collaboration; and Joshua Blumenstock for his perspectives and work to connect this work to direct social impact. I am thankful to all of them for serving on my committe and for their thoughtful advice