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Principles of High Performance Wi-Fi

Principles of High Performance Wi-Fi. Brian Mason Director of Product Marketing. Wi-Fi Needs. High speed connectivity for fast transfer of large data files (e.g. CAD, simulation software, etc) Robust coverage for reliability on mission critical projects

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Principles of High Performance Wi-Fi

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  1. Principles of High Performance Wi-Fi Brian Mason Director of Product Marketing

  2. Wi-Fi Needs • High speed connectivity for fast transfer of large data files (e.g. CAD, simulation software, etc) • Robust coverage for reliability on mission critical projects • Pervasive availability for easy collaboration any where. • Reliable enough to be considered suitable failover for wired networks • Secure connectivity to entrust proprietary data

  3. Wi-Fi Nightmares

  4. Wi-Fi Nightmares

  5. Wi-Fi Nightmares

  6. Wi-Fi Challenges • Higher User Density • Performance • Reliable Seamless coverage • Security • Resiliency

  7. Wired Faced same problem 15 years ago • Added bandwidth – Ethernet trumped ATM and Token Ring • Dedicated Resources – Switches beat hubs • Intelligence at the edge – Intelligent switches are the standard • Easier Deployment – more ports, fewer devices

  8. Wireless Following Wired’s lead • Six Trends in wireless making this possible: • Standardization of 802.11n (Increased Bandwidth) • Move from 2.4GHz to 5GHz (Increased Bandwidth) • Multi-Radio devices (Greater Capacity) • Directional Antennas (Greater range, fewer devices) • Embedded Threat Sensors (Increased Security) • Integrated Spectrum Analyzer (Easier Troubleshooting)

  9. 802.11n: The Basics • Should be ratified June 2009 • Faster • Up to 100 Mbps with first-gen pre-N products • Up to 300 Mbps with 802.11n draft 2.0 products • Ample bandwidth makes it easier for a single WLAN to support a mix of voice, video and data • Farther • More than 300 feet vs. 100 feet with 802.11a/b/g • Potential for lower infrastructure costs because fewer access points (APs) required to blanket an area

  10. 802.11n: The Basics • More Robust • MIMO technology mitigates interference and maintains broadband performance even with weak signals • More Secure • Wi-Fi Alliance certified 802.11n draft 2.0 products must include Wi-Fi Protected Access 2 (WPA2)

  11. 802.11n – Obtaining Higher Data Rates Spatial Multiplexing • Source data stream split and sent over separate antennas at the same time • Recombined at receiver using MIMO signal processing • Doubles, triples, or quadruples the data rate depending on the number of transmit antennas used Channel Bonding • Increasing the Bandwidth • Bonds two 20MHz channels to a 40MHz channel • Slightly more than doubles the bandwidth • Phased channel operation: ability to jump between 20 and 40Mhz channels

  12. 802.11n – MAC Improvements Reducing Overhead Improves Efficiency • Frame Aggregation • Block ACKs • Reduced Inter-frame spacing

  13. 802.11n Range and Data Rates • Longer Range or Higher Data Rates • Wi-Fi Certified data rates 300Mpbs • Most compatible with 802.11a • Backwards compatible with 802.11bg • Channel Bonding • Multiple Input/ Muliple Output (MIMO) • Spactial Multiplexing

  14. 5GHz vs 2GHz Spectrum

  15. 802.11 Channels – Cell Planning 802.11b/g Channels Available = 3 • Distance to cell with same channel is less than a single cell • Sensitive to co-channel interference (from other cells on the same channel) • If energy is weak, seen as interference • If energy is strong, stations will defer • Bleed-over retards higher data rates • Greatly reduces overall network capacity 802.11a Channels Available = 23 • High Performance: 8 times the capacity • Far less interference from cells on same channel • More channels to avoid interference

  16. 802.11 Channels – Interference Issues 802.11b/g uses the 2.4 GHz ISM band • Common devices cause interference • Bluetooth devices • Cordless phones • Microwave ovens • X10 wireless video cameras • HAM radio operators • Interference collides with the intended signal • Transmissions are garbled and data packets are retransmitted • Reduced end-user throughput and increased latency of data traversing the RF network 802.11a uses the 5GHz UNII band • Relatively interference free

  17. 802.11n Rates and Modes 802.11a/n (5GHz) 23 channels * 150Mbps = 3.4Gbps 802.11a (5GHz) 23 channels * 54Mbps = 1.2 Gbps 802.11g/n (2.4GHz) 3 channels * 150Mbps = 450 Mbps 802.11g (2.4GHz) 3 channels * 54Mbps = 162 Mbps 802.11b (2.4GHz) 3 channels * 11Mbps = 33 Mbps 150 17

  18. Multi-Radio vs Dual-radio Architectures Multiple Radios in a single AP (i.e. an Array) = MORE CAPACITY - Traditional APs have one or two radios - New multi-radio architectures have up to 4, 8, or 16 radios in a single device - Each radio has fixed bandwidth - Each radio can support a limited number of users at one time Multi-Radio Traditional AP: In a classroom of 30 students a dual radio AP will have 15 students per radio In the same classroom an Array would just have 2 or 3 students per radio

  19. Directional vs Omni-Directional Directional Antennas = GREATER RANGE • Better antenna gain • Better receiver sensitivity • Allows fewer devices cover a larger area • Typically 75% fewer devices and cable drops required

  20. Distributed vs Centralized • Distributed = HIGHER PERFORMANCE • Packet Processing at edge • Control plane at edge • Policy and security enforcement at edge • Encryption processing at edge • Just like Ethernet Switching • Central management • Central Controller + Thin Aps • Packet Processing at core • Control plane at core • Policy and security enforcement at core • Encryption processing at core • Central management Centralized Processing Distributed Processing

  21. Hardware-Based Line-Speed Encryption Encryption Engine Dedicated Monitor Radio Security • Security Performance • Use Line-rate Hardware Based Encryption • AES (WPA2) is Best • Hardware based encryption on client • Best to Use a Single Encryption Mode per SSID • Authentication: 802.1X • RADIUS Servers should be local • PMK Sharing = faster roaming • Intrusion Detection • Threats, Attacks, Compliance • Neighboring Networks • Requires: Dedicated Radio for RF Monitoring • Time sharing radios for IDS reduces performance especially for voice • You cant fix a problem if you don’tknow there is a problem Ethernet Switch Authentication Server Access Point / Array

  22. Wi-Fi Sponsor ’06 & ‘07 Best Design of the Year B e s t S t a r t u p Wi-Fi Array Antennas • The Xirrus Wi-Fi Array • Single Device • Superior Range and Capacity • 75% Less Devices and Cabling • Up to 16 Modular Radios • 802.11n Upgradeable • Advanced RF Management • Redundant Radios and Ethernet • Integrated Wi-Fi Switch • Integrated Spectrum Analyzer • Integrated Threat Monitor • Line Speed Hardware-based Encryption • Filtering and Firewalling • Complete Suite of Management and Planning Tools • Plan for the Success of your Wi-Fi Network! Radio Modules Array Controller

  23. The Future of Wi-Fi “The only effective way to deliver high-performance Wi-Fi is to have a centrally managed intelligent edge network – just like your wired networks do”

  24. Wi-Fi Reference Poster Series Xirrus Wi-Fi Reference Posters • Register at: www.xirrus.com/library • Email: posters@xirrus.com • Posters in the Series • 802.11a/b/g • 802.11n Principles • Wi-Fi Authentication • Wi-Fi Encryption • Wi-Fi Range Dynamics • Wi-Fi Network Architectures • Wi-Fi Cousins & Nephews • High Performance Wi-Fi • Also: • Reference Poster Podcast • Reference Poster Companion Guides • Webinars • White Papers • Design Guides

  25. Thanks Visit www.xirrus.com for - Wi-Fi posters - 802.11n webcast and podcast - Best Practices and design guides - Wi-Fi gadgets and widgets

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