A Guidebook for Mitigating Disruptive WiFi Interference at Airports (2015)

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A I R P O R T C O O P E R A T I V E R E S E A R C H P R O G R A M ACRP REPORT 127 TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2015 www.TRB.org Research sponsored by the Federal Aviation Administration Subscriber Categories Aviation  •  Data and Information Technology A Guidebook for Mitigating Disruptive WiFi Interference at Airports Michael Carroll Hollis Stambaugh SyStem Planning CorPoration Arlington, VA Joseph Kolesar Sage-SolutionS grouP, inC. Arlington, VA Stephen Berger tem ConSulting, lP Georgetown, TX Heidi Benaman Zachary Varwig Faith grouP, llC St. Louis, MO

AIRPORT COOPERATIVE RESEARCH PROGRAM Airports are vital national resources. They serve a key role in trans­ portation of people and goods and in regional, national, and inter­ national commerce. They are where the nation’s aviation system connects with other modes of transportation and where federal respon­ sibility for managing and regulating air traffic operations intersects with the role of state and local governments that own and operate most airports. Research is necessary to solve common operating problems, to adapt appropriate new technologies from other industries, and to introduce innovations into the airport industry. The Airport Coopera­ tive Research Program (ACRP) serves as one of the principal means by which the airport industry can develop innovative near­term solutions to meet demands placed on it. The need for ACRP was identified in TRB Special Report 272: Airport Research Needs: Cooperative Solutions in 2003, based on a study spon­ sored by the Federal Aviation Administration (FAA). The ACRP carries out applied research on problems that are shared by airport operating agencies and are not being adequately addressed by existing federal research programs. It is modeled after the successful National Coopera­ tive Highway Research Program and Transit Cooperative Research Pro­ gram. The ACRP undertakes research and other technical activities in a variety of airport subject areas, including design, construction, mainte­ nance, operations, safety, security, policy, planning, human resources, and administration. The ACRP provides a forum where airport opera­ tors can cooperatively address common operational problems. The ACRP was authorized in December 2003 as part of the Vision 100­Century of Aviation Reauthorization Act. The primary participants in the ACRP are (1) an independent governing board, the ACRP Oversight Committee (AOC), appointed by the Secretary of the U.S. Department of Transportation with representation from airport operating agencies, other stakeholders, and relevant industry organizations such as the Airports Council International­North America (ACI­NA), the American Associa­ tion of Airport Executives (AAAE), the National Association of State Aviation Officials (NASAO), Airlines for America (A4A), and the Airport Consultants Council (ACC) as vital links to the airport community; (2) the TRB as program manager and secretariat for the governing board; and (3) the FAA as program sponsor. In October 2005, the FAA executed a contract with the National Academies formally initiating the program. The ACRP benefits from the cooperation and participation of airport professionals, air carriers, shippers, state and local government officials, equipment and service suppliers, other airport users, and research orga­ nizations. Each of these participants has different interests and respon­ sibilities, and each is an integral part of this cooperative research effort. Research problem statements for the ACRP are solicited periodically but may be submitted to the TRB by anyone at any time. It is the responsibility of the AOC to formulate the research program by iden­ tifying the highest priority projects and defining funding levels and expected products. Once selected, each ACRP project is assigned to an expert panel, appointed by the TRB. Panels include experienced practitioners and research specialists; heavy emphasis is placed on including airport pro­ fessionals, the intended users of the research products. The panels pre­ pare project statements (requests for proposals), select contractors, and provide technical guidance and counsel throughout the life of the project. The process for developing research problem statements and selecting research agencies has been used by TRB in managing cooper­ ative research programs since 1962. As in other TRB activities, ACRP project panels serve voluntarily without compensation. Primary emphasis is placed on disseminating ACRP results to the intended end­users of the research: airport operating agencies, service providers, and suppliers. The ACRP produces a series of research reports for use by airport operators, local agencies, the FAA, and other interested parties, and industry associations may arrange for work­ shops, training aids, field visits, and other activities to ensure that results are implemented by airport­industry practitioners. ACRP REPORT 127 Project 01­23 ISSN 1935­9802 ISBN 978­0­309­30842­7 Library of Congress Control Number 2015932785 © 2015 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not­for­profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB or FAA endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not­for­profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the Airport Cooperative Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the Airport Cooperative Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report. Published reports of the AIRPORT COOPERATIVE RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at http://www.national­academies.org/trb/bookstore Printed in the United States of America

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. C. D. Mote, Jr., is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Victor J. Dzau is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. Mote, Jr., are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individu- als interested in the development of transportation. www.TRB.org www.national-academies.org

C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR ACRP REPORT 127 Christopher W. Jenks, Director, Cooperative Research Programs Michael R. Salamone, ACRP Manager Theresia H. Schatz, Senior Program Officer Terri Baker, Senior Program Assistant Eileen P. Delaney, Director of Publications Scott E. Hitchcock, Editor ACRP PROJECT 01-23 PANEL Field of Administration John Newsome, Greater Orlando Aviation Authority, Orlando, FL (Chair) Pamela E. Bell, Ross & Baruzzini, Inc., Bellevue, WA John A. Buckner, Jr., Salt Lake City Department of Airports, Salt Lake City, UT Timothy M. Mitchell, Boeing, Seattle, WA Jeffrey Rae, United Airlines, Chicago, IL Dawoud Stevenson, Savannah Airport Commission, Savannah, GA Kiem Hoang, FAA Liaison Alvin Logan, FAA Liaison Aneil Patel, Airports Council International–North America Liaison

ACRP Report 127: A Guidebook for Mitigating Disruptive WiFi Interference at Airports is a guidebook written for airport leadership and other stakeholders that describes the WiFi interference problems at airports and offers solutions to mitigate disruptions. Interference is addressed in the context of the business and regulatory structure within which airports operate. The guidebook is designed to provide practical assistance for improving WiFi per­ formance by enhancing the ability of airport authorities to identify when radio frequency interference is occurring and then how to eliminate, reduce or at least minimize its impact. The guidebook addresses issues at a variety of types and sizes of U.S. airports with the fol­ lowing considerations: • Quantification of the extent and magnitude of the interference problems; • Best technical and business practices to provide accessible, secure service with adaptable band width to meet the needs of all stakeholders; • Communication and collaboration efforts among parties to maximize the benefits of a cooperative approach; • Reference designs, adaptable to different airport environments (small, medium, large, domi­ nant carrier, no dominant carrier, and other tenant mix), including security requirements for all stakeholders; • Techniques for identifying and resolving interference issues outside reference designs; • Strategic vision that addresses potential impacts due to increasing demand, rapidly evolving technologies, and new uses (e.g., 802.11 ac, HD video, 4G backhaul); and • Total cost of ownership and return on investment, including intangibles. Wireless networks have become critical for various operational applications on the airport including baggage reconciliation, aircraft­to­gate data communications, facilities mainte­ nance, and security, among others. In addition to the operational applications, wireless net­ works have become an expectation of the public which is using an increasing variety of smart­ phones, tablets, and personal mobile hotspots. These uses compete for the same spectrum and have the potential to create major radio frequency interference that is dis ruptive to all users. The FCC ruled that airports could not regulate the use of the WiFi spectrum or prohibit tenants with exclusive leases from installing WiFi in their leasehold areas. FCC staff recom­ mended airports and tenants explore cooperative arrangements and innovative solutions to mitigate disruptive interference. Airport and airport tenants’ dependence on wireless networks is increasing and will com­ pound any interference problems that currently exist. Research was needed to quantify the impacts of interference to the end user and define mitigation solutions. F O R E W O R D By Theresia H. Schatz Staff Officer Transportation Research Board

Under ACRP Project 01­23, research was conducted by System Planning Corporation in association with Sage­Solutions, TEM Consulting, and Faith Group LLC. A survey was sent to 45 airports to obtain information about wireless system interference and disrup­ tions and the extent to which these problems affect operations. More in­depth research was conducted during site visits to 9 airports that represented all sizes of airports. In addition, measurements were taken of the RF spectrum and WiFi utilization for 93 gates and other passenger areas at 23 airports.

  1  Summary 5 Chapter 1  Radio Frequency Primer 7 Chapter 2   WiFi Service at Airports and the Problem  of Interference 7 WiFi at Airports 8 Network Management Arrangements 8 Causes of WiFi Interference and Disruption 16 Adjacent Channel Interference 16 Other Sources of Interference 17 Interference Mitigation Techniques 19 Other WiFi and Network Problems 21 Network Design Solutions to Reduce Interference 24 Dynamic Frequency Selection and Transmit Power Control Requirements 26 Automated Network Management 29 Chapter 3  Airports and Network Operators: Issues and Solutions 29 Service Level Agreements 34 Network Analytics 35 System Performance Oversight 36 Influence Management in a “Bring Your Own Device” Environment 37 Structure of Network Management 37 Emerging Trends 39 Chapter 4  Strategic Planning for Wireless Networks 40 The Strategic Plan 42 Reference Design 42 Network Performance Management 43 Automated Network Management 45 Chapter 5  Stakeholder Relationships and Business Model Options 46 Master Service Level Agreements 46 Shared Tenant Services 48 Business Model 50 Chapter 6  WiFi at Small and General Aviation Airports 51 Step 1: Identify WiFi Requirements Per Physical Areas 51 Step 2: Quantify Desired Service Levels and Begin Design 52 Step 3: Establish and Maintain Data C O N T E N T S

53 Chapter 7  References and Resources 53 Standards 53 Best Practices for WAN Interference Management 54 IEEE 802.11ac & 802.11ad 55 Technology Trends 55 Small Cell Interference 55 Radio Frequency Measurement 56 Multiple­in, Multiple­out 56 Other Articles & White Papers 58 Chapter 8  Acronyms and Definitions 58 Acronyms 59 Definitions 60 Appendix A  Radio Frequency Primer 76 Appendix B  Best Technical Practices to Ensure Accessible  WiFi Service 84 Appendix C  IEEE 802 Standards Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions.