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

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

53 C H A P T E R 7 This chapter is a compilation of recommended reading and resources on the topic. These resources each have significant value in gaining a better understanding of WiFi and the best methods for maximizing network efficiency. Standards related to the management of WiFi are also cited. Standards [1] IEEE 1900.2:2008: IEEE Recommended Practice for the Analysis of In-Band and Adjacent Band Interference and Coexistence between Radio Systems [2] ISO TR 20000-1:2011: Information Technology—Service Management [3] ISO TR 80001-1:2010 Application of Risk Management for IT-Networks Incorporating Medical Devices—Part 1: Roles, Responsibilities and Activities [4] ANSI/AAMI/IEC TR 80001-2-3:2012: Application of Risk Management for IT-Networks Incorporating Medical Devices—Part 2–3: Guidance for Wireless Networks [5] AAMI TIR 18:2008: Guidance on Electromagnetic Compatibility of Medical Devices in Healthcare Facilities Best Practices for WAN Interference Management [1] BAA’s Response to Ofcom’s Consultation, Higher Power Limits for License Exempt Devices, 2006. [2] Cisco Systems, Cisco Intelligent Airport Wireless (WI-FI) Network Solution, 2004. This white paper is now rather dated but shows how quickly this area is changing. For example, statements that laptops now are including WiFi and that there are over 10,000 WiFi hotspots in the U.S. now seem like ancient history. However, many of the basic management techniques presented continue to be used effectively. [3] Cisco Systems, Enterprise Mobility 4.1 Design Guide. Available at: http://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob41dg/ emob41dg-wrapper.html This book describes the design and implementation of the Cisco Unified Wireless Network solution for the enterprise, using the features incorporated in the Wireless LAN Controller software Release 4.1. [4] Hoglund, David, Are Mobile Medical Devices “Hospital Grade”? Meeting the Challenge of Today’s Healthcare WLANs, April 29, 2013. Available at: http://info.ixiacom.com/rs/ixiacom/images/Ixia-David-Hoglund-Medical- Device-Testing.pdf References and Resources

54 A Guidebook for Mitigating Disruptive WiFi Interference at Airports Integra Systems and Ixia provide this healthcare white paper focused on the growing need to validate and verify the performance of wireless medical devices and healthcare networks. They propose the need for proper validation as a critical paradigm change in the medical device and healthcare provider marketplace. The new model of testing and validating the performance described in this paper can decrease costs, mitigate serious risk to providers’ brand reputation, and vastly improve the overall quality of the wireless experience. [5] Raymond, Phil, The Wireless Challenge: Achieving a Robust and Reliable Network, Biomedical Instrumentation & Technology, May/June 2013. This article is a very useful overview, written by someone who deals with the issues on a daily basis. [6] Silver Peak Systems, Inc., Best Practices for Deploying WAN Optimization with Data Replication. Available at: http://www.silver-peak.com/sites/default/files/infoctr/silver-peak_wp_ best_practices_withdatareplication.pdf [7] Silver Peak Systems, Inc., Five Ways to Optimize Offsite Data Storage and Business Continuity Available at: http://www.silver-peak.com/sites/default/files/infoctr/silver-peak_wp_ optimize_offsite_dr.pdf [8] WiFi Alliance, WiFi in Healthcare: The Solution for Growing Hospital Communication Needs, 2011. Available at: http://www.wi-fi.org/downloads-registered/wp_Wi-Fi_in_Healthcare_ 20110217.pdf/Wi-Fi%25C2%25AE%2Bin%2BHealthcare%253A%2BThe%2Bsolution% 2Bfor%2Bgrowing%2Bhospital%2Bcommunication%2Bneeds%2B%25282011%2529 [9] WiFi Alliance, WiFi in Healthcare: Security Solutions for Hospital WiFi Networks, 2012. Available at: http://www.wi-fi.org/downloads-registered/wp_201202_Wi-Fi_Security_ for_Hospital_Networks-Final.pdf/Wi-Fi%25C2%25AE%2Bin%2BHealthcare%253A%2B Security%2BSolutions%2Bfor%2BHospital%2BWi-Fi%2BNetworks%2B%25282012%2529 [10] WiFi Alliance, WiFi in Healthcare: Improving the User Experience for Connected Hospital Applications and Devices, 2013. Available at: http://www.wi-fi.org/downloads-registered/wp_201305_Healthcare- Improving_User_Experience.pdf/Wi-Fi%25C2%25AE%2Bin%2BHealthcare%253A%2B Improving%2Bthe%2Buser%2Bexperience%2Bfor%2Bconnected%2Bhospital%2Bappli cations%2Band%2Bdevices%2B%25282013%2529 [11] Smith, Graham, Dense Apartment Complex Capacity Improvements with Channel Selec- tion and Dynamic Sensitivity Control, presentation to IEEE 802.11, IEEE 802.11 document IEEE 802.11-13/1487r2. This presentation claims dynamic sensitivity control produces improvements of: – 296% for Single Apartment Complex – 412% for Double Apartment Complex [12] Smith, Graham, Airport Capacity Analysis, IEEE 802.11-13/1489r2. This presentation extends the author’s apartment analysis to airports. IEEE 802.11ac & 802.11ad [1] Perahia, Eldad, and Gong, Michelle X., Gigabit Wireless LANs: An Overview of IEEE 802.11ac and 802.11ad, ACM SIGMOBILE Mobile Computing and Communications Review, Volume 15, Issue 3, July 2011, pgs. 23-33. Available at: http://www.informatik.uni-trier.de/~ley/pers/hy/p/Perahia:Eldad.html An excellent introduction to the history of the IEEE 802.11ac and 802.11ad standards, their development history, and use cases. Eldad Perahia, one of the authors, was chair of the IEEE 802.11ad committee and hence, an authoritative source for this information.

References and Resources 55 [2] Myles, A., and de Vegt, R., WiFi Alliance (WFA) VHT Study Group Usage Models, IEEE 802.11-07/2988r4, March 19, 2008. Available at: https://mentor.ieee.org/802.11/dcn/07/11-07-2988-04-0000-liaison-from- wi-fi-alliance-to-802-11-regarding-wfa-vht-study-group-consolidation-of-usage- models.ppt A presentation of the WiFi Alliance usage models used as a basis for the IEEE 802.11ac and 802.11ad standards. [3] WildPackets, 802.11ac and 802.11ad: What They Are and How They Will Impact Your Net- work, April 5, 2012. Technology Trends [1] Department of Defense, Electromagnetic Spectrum Strategy (EMS), September 11, 2013. The DoD sets forth its spectrum strategy and in doing so highlights how it will address a variety of issues in spectral management. This document is significant for the insight it gives to future DoD activities related to spectrum management. [2] Frenzel, Louis E., Freescale’s Ritu Favre Discusses Today’s RF Technologies, Electronic Design, October 3, 2013. Component manufacturers work closely with their leading customers to support their needs and have the components available for the next generation of technology. This article is a good example of how that methodology can give insight to emerging trends. Freescale is a leading provider of RF components, particularly power amplifiers, and a good example of how new components show the next steps their customers will be taking with their products. [3] Frenzel, Louis E., WiFi and Bluetooth Rule the Airwaves, Electronic Design, July 11, 2013. A very interesting article discussing the growing dominance of Bluetooth and WiFi operating in the 2.4 GHz ISM band. [4] The joint ACI, Airline Business, and SITA report, The 2012 Airport IT Trends Survey. This is a very useful survey of airport technology trends and priorities. [5] Radisys, LTE-A and Small Cell Deployment Strategies, May 2013. Presented in an eBook format, this document presents Radisys’s views on the development of heterogeneous networks and the introduction of Long Term Evolution—Advanced (LTE-A) features. It discusses the advantages it sees these developments bringing to network providers and their users. Small Cell Interference [1] The Small Cell Forum, Release 3: Urban Foundations, WiFi/Cellular Radio Co-existence in Enterprise Products, Document #064.03.01, December 2013. Most recent release available at: http://www.scf.io This very brief report provides important conclusions on the potential for interference from small cell deployments, but unfortunately keeps the underlying research confidential. [2] Worsham, J., WiFi Femtocell Interference Testing Final, 2010. [3] 3GPP. TR 36.816: Evolved Universal Terrestrial Radio Access (E-UTRA); Study on Signaling and Procedure for Interference Avoidance for In-Device Co-existence, 2011. Radio Frequency Measurement [1] Agilent Technologies, Digital Modulation in Communications Systems—An Introduction, Application Note AN1298.

56 A Guidebook for Mitigating Disruptive WiFi Interference at Airports [2] Feher, Gabor, Bit-Error Analysis in WiFi Networks Based on Real Measurements, 5th Inter- national ICST Conference on Access Networks, Nov. 4, 2010. This is a very useful paper for several purposes. It provides a good rationale for understand- ing network performance at multiple layers and how cyclic redundancy check (CRC) and other error-correcting mechanisms can hide what is happening at lower layers. The measurements made give significant insight to network performance and how to adapt by decreasing data rates. [3] Frenzel, Louis, Understanding Error Vector Magnitude, Electronic Design, October 10, 2013. Available at: http://electronicdesign.com/engineering-essentials/understanding-error- vector-magnitude An excellent and well-illustrated tutorial on modern RF modulations and error vector magnitude. [4] IxChariot Roaming Test Plan Available at: http://www.ixiacom.com/sites/default/files/resources/test-plan/wlan_ roaming_0.pdf Ixia’s recommended test plan for evaluating WLAN roaming using their IxChariot. [5] VoIP Testing with IxChariot Available at: http://www.ixiacom.com/sites/default/files/resources/test-plan/voip_0.pdf Ixia’s recommended test plan for evaluating VoIP performance over WLANs using their IxChariot. [6] Scott, A.W., and Frobenius, R., RF Measurements for Cellular Phones and Wireless Data Systems, Wiley/IEEE, 2008. [7] Shafik, R.A., et al., On the Error Vector Magnitude as a Performance Metric and Comparative Analysis, IEEE 2nd International Conference on Emerging Technologies, November 2006. Multiple-in, Multiple-out [1] Bhagavatulay, R., Heath, R.W., Jr., and Linehan, K., Performance Evaluation of MIMO Base Station Antenna Designs, Antenna Systems & Technology, Vol. 11, No. 6, Nov./Dec. 2008. Other Articles & White Papers [1] ISCO International, Airport Communications at Risk, 2012. [2] Cisco Systems, Wireless RF Interference Customer Survey Results, 2010. Available at: http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10981/ white_paper_c11-609300.pdf The survey results are very interesting but more useful as a representation of generally held opinion than a research result. Based on this survey, RF interference is clearly an issue in the minds of a majority of IT managers. However, to verify if that belief is accurate requires objective evidence to differentiate true RF interference from other sources of performance degradation. [3] Cisco Systems, 20 Myths of WiFi Interference: Dispel Myths to Gain High-Performing and Reliable Wireless. [4] Cisco Systems, The Future of Hotspots: Making WiFi as Secure and Easy to Use as Cellular. [5] Cisco Systems, Guidelines and Tools for Migrating to the Cisco Unified Wireless Network. [6] Kerner, S.M., Cisco Aims for Clean Air on WiFi, 2010. [7] Frenzel, L., WiFi and Bluetooth Rule the Airwaves, Electronic Design, July 11, 2013. This article gives an excellent overview of WiFi and Bluetooth protocols. Its main purpose is to discuss their market dominance, which it accomplishes with considerable insight. [8] Visiwave, Visualize Your Wireless Network. Available at: www.visiwave.com

References and Resources 57 [9] Bandspeed, Understanding the Effects of Radio Frequency (RF) Interference on WLAN Performance and Security, 2010. [10] Howard Preston Cinema Systems, The Wireless Jungle, 2009. [11] IEEE 802 Working Group Project Timelines Available at: http://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm [12] Metageek, Interference Identification Guide. [13] Novarum Inc., High Density WLAN Comparison Testing: Aruba, Cisco and Juniper, September 2013. A useful study showing the capacity performance differences using equipment from different vendors. [14] Paul, U., Kashyap, A., Maheshwari, R., and Das, S.R., Passive Measurement of Interference in WiFi Networks with Application in Misbehavior Detection, 2013. [15] Intel, USB 3.0* Radio Frequency Interference Impact on 2.4 GHz Wireless Devices, April 2012. This paper from Intel explains the reason why USB 3.0 data connections can cause WiFi interference and offers suggestions about how it can be mitigated. The paper is well-researched and presented and illustrates an important example of a class of WiFi interference from unintentional emitters. [16] Coleman, D., and Diener, N., Protecting WiFi Networks from Hidden Layer 1 Security Threats, 2007. [17] Schneider Electric Industries SAS, WiFi in the 5 GHz Band, April 2011. Available at: www.schneider-electric.co.uk This white paper gives a good overview and history of the use of WiFi in the 5 GHz band and the role DFS and transmit power control had in its proliferation. The paper also provides a good summary of the state of international harmonization for the channels in this band. [18] Matsumoto, Y., Takeuchi, M., Fujii, K., Sugiura, A., and Yamanaka, Y., A Time-Domain Microwave Oven Noise Model for the 2.4 GHz Band, IEEE Transactions on Electromagnetic Compatibility, Vol. 45, No. 3, August 2003. [19] Wireless World Research Form, Working Group C, Communication Architectures and Technologies, Multi-RAT Network Architecture, June 30, 2013. [20] Zeto, J., Bringing WiFi to Healthcare, Wireless Design Magazine, July-Aug 2013. [21] Thonet, G., et al., Schneider Electric Innovation Department, ZigBee—WiFi Coexistence. [22] Zubow, A., Sombrutzki, R., and Chausse, R., Reinvestigating Channel Orthogonality— Adjacent Channel Interference in IEEE 802.11n Networks, SAR-PR-2011-14, Humboldt University, 2011. Available at: http://sar.informatik.hu-berlin.de/research/publications [23] Villegas, E., López-Aguilera, E., Vidal, R., and Paradells, J., Effect of Adjacent-Channel Interference in IEEE 802.11 WLANs Available at: http://upcommons.upc.edu/e-prints/bitstream/2117/1234/1/CrownCom07_ CReady.pdf [24] Lakshmanan, S., Lee, J., Etkin, R., Lee, S.-J., and Sivakumar, R., Realizing High Performance Multi-Radio 802.11n Wireless Networks. Available at: http://www.ece.gatech.edu/research/GNAN/archive/tr-mrd.pdf