Shanghai Breakout: Advanced RF Design and Troubleshooting
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George Stefanick presented on advanced RF design and troubleshooting of WiFi networks. He discussed designing WiFi networks for coverage and capacity, including considering application requirements, client devices, channel planning, transmission power levels, and ensuring proper cell overlap and separation. He also covered the methodology for troubleshooting WiFi networks, including collecting information from end users, inspecting devices, reproducing issues, and using various monitoring tools.
Shanghai Breakout: Advanced RF Design and Troubleshooting
- 1. Advanced RF Design and Troubleshooting George Stefanick December 2014
- 2. Wireless Architect @ Houston Methodist Hospital – 5 years • Manage 3,000 Access points • 11,000 concurrent clients / 26,000 total • Deployed our first AWO (All Wireless Office) 300 users / 800 devices Independent Consultant (training, site survey, security, deployment and troubleshooting) Blog: www.my80211.com , www.nostringsattachedshow.com, Cisco Support Community and Aruba. 2 Started WiFi in late 90’s Vendor and Vendor neutral certifications Aruba MVP 2014 Cisco VIP 2012,2013 and 2014 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Who Am I ? Interop - Speaker 2014 Las Vegas / NYC (Wifi Tools) Cisco Live - Speaker 2013 Orlando (Deployment of 802.11ac) Published Technical Editor – Sybex Project: CCNA Wireless Study Guide by Todd Lammle Published Technical Editor – Cisco Press Project: Designing and Deploying 802.11 Wireless Networks: A Practical Guide to Implementing 802.11n and 802.11ac Wireless Networks For Enterprise-Based Applications (2nd Edition) (Networking Technology) by Jim Geier
- 3. 3 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf In the next 60 minutes Take (2) things away from this session you didn’t know before then this session was a success!! “I personally define my own success in how I can help others on their journey in WiFi”
- 4. CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved 4 #AirheadsConf Agenda Designing WiFi Networks for RF Coverage / Capacity (Overview) The Methodology of Troubleshooting WiFi Networks WiFi Tools and Monitoring For WiFi Networks
- 5. 5 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Designing WiFi Networks for RF Coverage / Capacity • Designing WiFi for RF Coverage and Capacity
- 6. 6 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Designing WiFi Networks for RF Coverage / Capacity We need to understand the technical reasons “WHY” there is a difference in design approach when comparing coverage and density designs ..
- 7. WiFi Radios Listen, Transmit and Receive 7 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Fundamentals CSMA-CA NAV (Network Allocation Vector) • Layer 2 • NAV (Time Busy After Transmission) (ACKs, SIFS) CCA (Clear Channel Assessment) • Layer 1 • Energy Detect • CS Carrier Sense (Preambles / PHY Headers)
- 8. 8 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Fundamentals Preambles and PHY Headers –Aruba Networks White Paper 802.11ac In-Depth
- 9. 9 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Fundamentals Constellations –Aruba Networks White Paper 802.11ac In-Depth
- 10. 10 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Fundamentals Constellations QPSK – 2 bits per modulation symbol at 90 degrees phase 4 wave forms (phases)
- 11. 11 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Fundamentals Constellations
- 12. 12 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Fundamentals Layer 1 and Layer 2
- 13. 13 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Fundamentals Understand (CCI) Majority of interference on todays WiFi networks come from our own access points. (CCI) • High Power Radios • Excessive Gain Antennas • Excessive Overlap • Poor Designs
- 14. x x 14 x x x x x CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved x x x x x #AirheadsConf Fundamentals TX Power and CSMA-CA x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x TX Power In Relation To Cell Size
- 15. 15 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Designing for WiFi Coverage and Capacity Typical Questions to Ask Type of applications • Real time (Voice / Video) • EMR (Electronic Medical Record) • PoS (Point of Sale) • WMS (Warehouse Management System) Type of WiFi devices • Laptops • Handhelds • Phones How many WiFi devices UP/DOWN Bandwidth (Mbps) Requirements Bands 2.4 GHz / 5 GHz Area of coverage Seamless Roaming Requirements* WiFi Design WiFi Grade • Data • Voice • Vocera* • RTLS • Density (Indoor / Outdoor) Identify High density areas • Conference Rooms • Lecture Halls Security Requirements • PCI • HIPPA
- 16. Designing for WiFi Coverage and Capacity Generally Accepted WiFi Specifications 16 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf DATA Cell Size @ -75 RSSI / 20% Cell Overlap VOICE Cell Size @ -67 RSSI / 25% Cell Overlap VOCERA* Cell Size @ -67 RSSI / 25% Cell Overlap RTLS Cell Size @ -67 RSSI / 25% Cell Overlap (Edge Coverage) DENSITY Cell Size @ ?? RSSI / ??% Cell Overlap
- 17. Designing for WiFi Coverage and Capacity Bands 2.4 GHz / 5 GHz - Design for the future! 17 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf 2.4 GHz Longer Wave Length (Longer Distance) Most popular WiFi Frequency Unlicensed Over crowded Many devices operate on 2.4 Limited channel selection (3 Channels) 5 GHz Shorter Wave Length (Shorter Distance) Popular WiFi Frequency Unlicensed 20+ Channels DFS Not all clients support all channels Careful with 2.4 GHz / 5 GHz enabled WLANs. Some client radios don’t make the best decisions. Aruba’s Client Match aids with sticky clients.
- 18. Designing for WiFi Coverage and Capacity Channel Bonding – Should You Channel Bond? 20 MHz / 40 MHz / 80 MHz 18 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Just because you can bond 80 MHz doesn’t mean you should! Let the design requirements dictate channel width. You may have specific Access points bonding at 40 / 80 MHz while others are at 20 MHz. Channel reuse is a must to consider during any design!
- 19. Designing for WiFi Coverage and Capacity 19 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Channel Separation – 20 dBm 6 1 11 11 6
- 20. Designing for WiFi Coverage and Capacity 20 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Channel Separation
- 21. Designing for WiFi Coverage and Capacity 21 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Disable Low PHY Rates DSSS / HRDSSS 1 PHY 2 PHY 5.5 PHY 11 PHY ERP-OFDM / OFDM 6 PHY 9 PHY
- 22. Designing for WiFi Coverage and Capacity 22 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf High Channel Utilization
- 23. TX Power – Design for the lowest common device? 23 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Designing for WiFi Coverage and Capacity
- 24. Example Excessive Transmission Power 1 Access Point Seen At -90 dBm – 250k sq feet Warehouse 24 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Designing for WiFi Coverage and Capacity
- 25. 25 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Example Excessive Transmission Power -60 dBm -70 dBm -80 dBm 100% CCC or CCI Designing for WiFi Coverage and Capacity
- 26. Designing for WiFi Coverage and Capacity 26 TX Power @ 6mW CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Floor to Floor Coverage 1 Floor Below 2 Floors Below
- 27. Designing for WiFi Coverage and Capacity 27 TX Power @ 12mW CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Floor to Floor Coverage 1 Floor Below 2 Floors Below
- 28. Designing for WiFi Coverage and Capacity 28 TX Power @ 25mW CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Floor to Floor Coverage 1 Floor Below 2 Floors Below
- 29. Designing for WiFi Coverage and Capacity 29 TX Power @ 50mW CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Floor to Floor Coverage 1 Floor Below 2 Floors Below
- 30. Designing for WiFi Coverage and Capacity 30 TX Power @ 100mW CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Floor to Floor Coverage 1 Floor Below 2 Floors Below
- 31. Designing for WiFi Coverage and Capacity 31 TX Power @ 200mW CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Floor to Floor Coverage 1 Floor Below 2 Floors Below
- 32. Designing for WiFi Coverage and Capacity 32 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Example Hallway Design
- 33. Designing for WiFi Coverage and Capacity 33 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Limit Signal Pollution • Shape Signal • Antennas • Walls • Low Transmission Power • Proper Channel Assignment
- 34. Designing for WiFi Coverage and Capacity 34 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Do The Math – Maximize Your Performance Application Bandwidth Requirements • Web Browsing • Video • VoIP Client Device Types Maximum Clients Per Cell
- 35. Designing for WiFi Coverage and Capacity 35 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Outdoor – These Fundamentals Apply Mining Oil / Gas Stadium Green Area
- 36. Designing for WiFi Coverage and Capacity 36 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Success Starts Here • Small cells low power • Shape your signal • Disable the low PHY rates • Proper channel plan • Proper cell overlap • Know your application requirements • Know your clients
- 37. 37 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf The Methodology of Troubleshooting WiFi Networks • The Methodology of Troubleshooting WiFi Networks
- 38. 38 Mental Check Box CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf The Methodology of Troubleshooting WiFi Networks Is the area of coverage designed and configured correctly ? If yes, and no changes to (ARM) then move on to device debugs, logs and WiFi Analyzer. If no, fix the area of coverage Where there any changes to the infrastructure, device configuration or application that could cause this issue? If yes, understand what changes were made. If no, move on to device, debugs, logs and WiFi Analyzer.
- 39. Collect End User Data / Field Visit 39 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf The Methodology of Troubleshooting WiFi Networks What is the issue from the end user perspective. Get detailed description of the problem. Drop voice calls; Static calls; One way speech; Slow connection; Can’t Connect ; Specific Apps don’t work; Multicast feature not working “Call to many”. What device(s) are involved ? Inspect device for damage; Driver Rev.; Configuration. Can the issue be reproduced ? ALWAYS try and get the device to fail yourself; Reproduce the failure. In almost all cases if you can get it to fail. You can resolve the problem quicker. Test against known working devices side by side. Is anyone else having a similar issue ? If so, then track down these users and question them and compare stories. Best to do one on one discussion and not group. Are there any commonalities or differences in data collected ? Is this isolated to a certain area of coverage; Certain population of devices or users. When did this problem start happening? Correlate to any possible network changes or pushes.
- 40. 40 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf The Methodology of Troubleshooting WiFi Networks Physically Inspect The Device
- 41. 41 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf The Methodology of Troubleshooting WiFi Networks Know Your Clients • Cardiac Imaging • Electronic Medical Record (EMR) • Mobile Ultrasound • Mobile Picture Archiving and Communications systems (PACS) • RTLS • Mobile Robots • Infusion Pumps • Handheld Scanners • Cows (Computer on Wheels) • Cisco 7925 Handsets • Vocera Badges • Mobile Cisco TelePresence VX Clinical Assistant • Roche Diagnostics ACCU-CHECK • Mobile EKG Carts • Mobile Med Dispensing Carts • WorkGroup Bridges (WGB) • Mobile Deaf Response Devices • Patient Video Monitoring Carts • DaVinci Simulators • Laptops • Tablets
- 42. 42 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf The Methodology of Troubleshooting WiFi Networks Clients Hear RSSI Differently
- 43. 43 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks • WiFi Tools and Monitoring For WiFi Networks
- 44. 44 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks Spectrum Analyzer
- 45. Wireless NICs, External USB Hubs, and Noise 45 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks
- 46. 46 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks Site Survey (Active, Passive, Virtual)
- 47. 47 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks Site Survey (Active, Passive, Virtual)
- 48. 48 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks Site Survey Rig
- 49. 49 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks Sniffer
- 50. 50 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks Mobile 802.11ac 3x3:3 (beta) BY FLUKE AIRMAGNET
- 51. 51 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf WiFi Tools and Monitoring For WiFi Networks Aruba AirWave
- 52. 52 CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved #AirheadsConf Education “Having a powerful tool in knowledgeable hands is the difference between owning a wireless problem or having a wireless problem owning you”
- 53. Thank You 53 #AirheadsConf CONFIDENTIAL © Copyright 2014. Aruba Networks, Inc. All rights reserved
Editor's Notes
- #4: Q: Who in the room has been in wifi 1-3 years Q: Who in the room has been in wifi 3-6 years Q: Who in the room has been in wifi 6+ years
- #6: Coverage designs have existed since day one in WiFi High density isnt anything new. It has been around for years. However, large outdoor venus like stadiums have given new meaning to high density design.
- #7: Coverage designs have existed since day one in WiFi High density isnt anything new. It has been around for years. However, large outdoor venus like stadiums have given new meaning to high density design.
- #8: ANYONE cn be trained where to put an access point on a map with survey software … BUT UNDERSATNDING WHY is the most important reason
- #9: If having a conversaion about frequency and cell size. We have to mention CSMA-CA
- #10: Bit Error rate mention
- #11: Bit Error rate mention
- #12: Bit Error rate mention
- #13: Before I go any further let discuss CSMA-CA.
- #14: Phone
- #15: CSMA – CA layer 1 / layer 2 CCA (ED) / NAV Preamble, PHY headers Wifi was orginally deisned without qos. Its purpose was equal access for all
- #16: The short list of questions ..
- #17: Typically when designing for coverage you design to blanket areas of coverage with a particular grade of wireless network.
- #25: Typically when designing for coverage you design to blanket areas of coverage with a particular grade of wireless network.
- #26: Typically when designing for coverage you design to blanket areas of coverage with a particular grade of wireless network.
- #33: Typically when designing for coverage you design to blanket areas of coverage with a particular grade of wireless network.
- #35: Typically when designing for coverage you design to blanket areas of coverage with a particular grade of wireless network.
- #38: Coverage designs have existed since day one in WiFi High density isnt anything new. It has been around for years. However, large outdoor venus like stadiums have given new meaning to high density design.
- #44: Coverage designs have existed since day one in WiFi High density isnt anything new. It has been around for years. However, large outdoor venus like stadiums have given new meaning to high density design.
- #45: If having a conversaion about frequency and cell size. We have to mention CSMA-CA
- #47: If having a conversaion about frequency and cell size. We have to mention CSMA-CA
- #48: If having a conversaion about frequency and cell size. We have to mention CSMA-CA
- #49: If having a conversaion about frequency and cell size. We have to mention CSMA-CA
- #50: If having a conversaion about frequency and cell size. We have to mention CSMA-CA
- #51: If having a conversaion about frequency and cell size. We have to mention CSMA-CA
- #52: If having a conversaion about frequency and cell size. We have to mention CSMA-CA