On the Feasibility of Providing Affordable Broadband Services using Backhaul in TV White Spaces Submitted in partial fulfillment of the requirements of the degrees of Master of Technology by Gaurang Naik Roll No. 123079009 Supervisors: Prof. Abhay Karandikar & Prof. Animesh Kumar DEPARTMENT OF ELECTRICAL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY BOMBAY JUNE, 2015 Approval Sheet This thesis entitled On the Feasibility of Providing Affordable Broadband Ser- vices using Backhaul in TV White Spaces by Gaurang Naik (Roll No. 123079009) is approved for the degree of Master of Technology in Communication and Signal Processing. Examiners Supervisors Chairperson Date: Place: Declaration I declare that this written submission represents my ideas in my own words and where others' ideas or words have been included, I have adequately cited and referenced the original sources. I also declare that I have adhered to all principles of academic honesty and integrity and have not misrepresented or fabricated or falsified any idea/data/fac- t/source in my submission. I understand that any violation of the above will be cause for disciplinary action by the Institute and can also evoke penal action from the sources which have thus not been properly cited or from whom proper permission has not been taken when needed. Gaurang Naik Date: Roll No: 123079009 To Amma & Anna Acknowledgements I would like to express my sincere gratitude to my supervisors, Prof. Abhay Karandikar and Prof. Animesh Kumar for the invaluable guidance they have provided over the last three years. The discussions I have had with them have helped me give a definite direc- tion to my thought process. Their enthusiasm has been a source of constant motivation for me throughout my stay at IIT Bombay. I will always be grateful to Karandikar Sir for the innumerable opportunities given to me to interact with some of the most intellectual people I have come across. A large part of the work done in this thesis is collaborated with my friend and colleague Sudesh Singhal. We have been working on this project from day-1 at IIT Bombay, and I would like to sincerely thank him for the support he has provided throughout. I have had few of the best moments in the InfoNet Lab and the Wireless Networks Lab with all the lab members. I would like to specially thank Soumik Ghosh and Rajeev Kumar for the time we spent during the project deployment at Palghar and in the lab. I am also thankful to Sonal, Dhanashree, Aditya Sir, Sangeeta Ma'am, Shubhada Ma'am and Tusharika for helping me on innumerable occassions in the InfoNet Lab. I would simply not have been here had it not been for my parents' support, love and motivation. I am extremely fortunate to be their son, and will always remain indebted to them. Their immense faith in me made it possible for me to come to IIT Bombay, and survive here for three years. I also thank Priyanka, my partner in life and my best friend for all the support she has given me. Without my parents and Priyanka, none of what I am today would have been possible. I dedicate this thesis to them! Finally, I would like to thank my dearest friends Kumar, Venkhat, Shrikant, Pravjyot, Shashi, Navneet, Mayank and Naireeta for making my stay at IIT Bombay one of the most wonderful and enriching experience in life. All of you turned the Wireless Networks Lab into my home away from home. Thank you all! June 3, 2015 Gaurang Naik Abstract Licensed but unutilized television (TV) band spectrum is called as TV white space in the literature. Ultra high frequency (UHF) TV band spectrum has very good wireless radio propagation characteristics. Even though research issues related to TV White Spaces started emerging only after the FCC regulations in 2009, several issues have been identified and studied extensively in literature. These research problems range right from estimating the available White Space in TV band and proposing ideas for interference avoidance to predicting the use cases of TV White Space operations and proposing solutions for the same. Most of the research pertaining to TV White Spaces started from United States, Japan and European countries. In this report, some key questions regarding TV White Space operations in India have been raised and some solutions have been offered. We first look at the global scenario for usage of TV White Space. Regulations and study of quantitative analysis of TV White Space in different countries have been studied. TV band utilization in India is much different and interesting as compared to that in other countries. Owing to the presence of a single TV broadcaster in India, much of the TV band remains underutilized in India. This calls for applications different from those being studied in other countries of the world. We look at one such application | affordable provision of broadband services, especially in the rural areas. The implementation and planning details of a pilot test-bed in the Palghar district of Maharashtra state have been outlined, and some preliminary experimental results have been presented. In any wireless network using TV white spaces (either for backhaul or access), a geo- location database can be used for the protection of the terrestrial TV broadcast receivers, and the coexistence of secondary devices. To the best of our knowledge, though TV White Space calculations are available, an active online database does not exist for India. The development of the first TVWS database for India is detailed and is released for public i access. A standardized protocol to access the TV White Space database on a readily available hardware platform is implemented. A hardware prototype, which is capable of querying the TV White Space database and operating in the TV band without causing harmful interference to the TV receivers in UHF TV bands, is developed. The source code of our implementation has been released under the GNU general public license version 2.0. ii Contents Abstract i 1 Introduction1 1.1 Present Status of Broadband in India....................1 1.1.1 Rural Broadband Challenges in India................1 1.1.2 National Optical Fiber Network Plan................2 1.1.3 Middle Mile/ Last Mile Problem...................2 1.2 TV White Space - A Potential Solution to the Rural Broadband Problem3 1.2.1 Primary and Secondary Users....................4 1.2.2 TV White Spaces and Rural Broadband..............4 2 TV White Space Around the World6 2.1 TV White Space in United States......................6 2.1.1 Regulations..............................6 2.1.2 Spectrum Sensing...........................8 2.1.3 Geolocation Databases........................8 2.1.4 Beacon.................................9 2.1.5 Availability of TV White Space in United States.......... 10 2.2 TV White Space in United Kingdom.................... 10 2.2.1 Regulations.............................. 10 2.2.2 Availability of TV White Space in United Kingdom........ 13 2.3 TV White Space in Japan.......................... 14 2.3.1 Regulations.............................. 14 2.3.2 Availability of TV White Space in Japan.............. 15 2.4 TV White Space in Europe......................... 15 2.4.1 Regulations.............................. 15 2.5 TV White Space in India........................... 16 2.5.1 How is the Indian Situation Different?............... 17 3 Test-bed for Affordable Broadband in India using Backhaul in TV White Space 19 3.1 Proposed Solution for Rural Broadband and Associated TV White Space Backhaul.................................... 19 3.1.1 Architecture for TV White Space Based Network Operations in India 21 3.1.2 Architecture for Database Assisted TV White Space Operations in India.................................. 22 3.1.3 Regulatory Approach for the Use of TV White Space in India.. 23 3.1.4 Details of the Proposed Test-bed.................. 24 iv 3.1.5 Selection of Sites for Test-bed.................... 24 3.2 Topographic Details of Wireless Nodes................... 26 3.3 Equipment for TV White Space....................... 28 3.3.1 Available Products/Prototypes................... 30 3.4 IP Connectivity Details............................ 31 3.4.1 Private IP-addresses to Enable Networking within the Wireless Lo- cal Area Network........................... 31 3.5 Experimental Results............................. 34 4 Implementation of Protocol to Access White Space (PAWS) Database on OpenWrt platform 43 4.1 OpenPAWS: Protocol Details........................ 44 4.1.1 Format of PAWS Messages...................... 46 4.2 Implementation Architecture......................... 47 4.2.1 TV White Space Database for India................. 48 4.3 Experimental Results............................. 52 5 Conclusions 56 5.1 Summary................................... 56 5.2 Future Work.................................. 57 5.2.1 Minimum Amount of Spectrum Needed for Target Quality of Service 57 5.2.2 Frequency of Operation and Coexistence Study with Adjacent Band Technologies.............................. 57 5.2.3 Spectral Mask and Out-of-band Emissions............. 57 5.2.4 Element Management System and Control Server......... 58 5.2.5 Implementation of Scheduling Algorithms, Extensions of Frottle for Multi-hop, Interference Management................ 58 5.2.6 Technology to be Used for Backhaul Network........... 58 5.2.7 Study of Coexistence in Multi-operator Environment....... 58 5.2.8 Study of Propagation Model in the 470-585Hz Band in the Indian Context................................ 59 Appendix A Compilation of RouterBoard 433AH in Bridged AP and Routed AP/Client modes 61 A.1 Make kernel and rootfs files for the desired OS............... 61 A.2 Flash kernel and rootfs files into the RouterBoard............. 63 A.3 Configure relevant files and install selected tools.............. 65 Appendix B Compilation of OpenWrt Attitude Adjustment 12.09 from source-code 68 B.1 Operation mode of RouterBoard 433AH.................. 69 B.1.1 Bridged AP.............................. 69 B.1.2 Routed AP.............................. 70 Publications 83 v List of Figures 1.1 Number of Habitat clusters in India and share of population.......3 1.2 The concept of TV White Space.