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Wireless Networking

Wireless Networking. 04 September 2004 Quintin Krisp. Overview. Wireless LAN Applications Wireless LAN Technology IEEE 802.11 Standard IEEE 802.11 Protocol Architecture IEEE 802.11 Relatives Wi-Fi Security. Wireless LAN Applications. LAN Extension:

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Wireless Networking

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  1. Wireless Networking 04 September 2004 Quintin Krisp

  2. Overview • Wireless LAN Applications • Wireless LAN Technology • IEEE 802.11 Standard • IEEE 802.11 Protocol Architecture • IEEE 802.11 Relatives • Wi-Fi Security

  3. Wireless LAN Applications • LAN Extension: • Buildings with large open areas (e.g. Manufacturing plants, Warehouses) • Historical buildings: may not damage building • Small offices: wired LANs not economical • May be mixed with fixed wiring system (hence LAN extension) • Either a single-cell or multiple-cell wireless LAN • Cross-building interconnection: • Point-to-point wireless link between buildings (e.g. Rural Monash Campuses) • Typically connecting bridges or routers • Used where cable connection not possible (e.g. across a street)

  4. Single Cell Wireless LAN • Control module (CM) and User Module (UM).

  5. Multi-Cell Wireless LAN

  6. Wireless LAN Applications • Nomadic access: • Between a LAN hub and mobile data terminal (e.g. laptop) • Transfer of data from laptop to server • Campus or cluster of buildings • Ad hoc networks: • Peer-to-peer (no centralized server) • Temporary connection (e.g. conference) a) Infrastructure Wireless LAN b) Ad hoc LAN

  7. Wireless LAN Technology • Infrared (IR) LANs: • Individual cell of IR LAN limited to single room • IR light does not penetrate opaque walls • More immune to electromagnetic interference (radio transmission or microwave ovens) • No licenses required • Spread spectrum LANs: • Mostly operate in ISM (industrial, scientific, and medical) bands • No Federal Communications Commission (FCC) licensing is required in USA • Narrowband microwave: • Microwave frequencies but not use spread spectrum • Some require FCC licensing

  8. Electromagnetic Spectrum for Telecommunications

  9. 802.11 Standard • IEEE 802 committee began in 1987 within the IEEE 802.4 group • Initial interest developing ISM-based wireless LAN using equivalent of token-passing bus MAC protocol • Token bus not suitable for radio medium, caused inefficient use of the radio frequency spectrum • IEEE 802.11 formed in 1990 as new working group devoted specifically to wireless LANs

  10. 802.11 Protocol Architecture • Distributed Coordination Function DFC • Lower MAC sublayer, uses Ethernet contention algorithm to provide access to all traffic • Contention protocol designed to handle two or more stations accessing network traffic simultaneously • Point Coordination Function (PCF) • Centralized MAC algorithm to provide contention-free service • AP polls according to list, no collisions occur • Logical Link Control (LLC) • Provide an interface to higher layers • Performs basic link-layer functions such as error control

  11. 802.11 Protocol Architecture

  12. 802.11 Relatives • 802.11d: Modification to comply with other countries • 802.11e: Add Quality of Service (QOS) • 802.11f: Improve communication between APs for authentication • 802.11h: Modification to comply with Europe • 802.11i: Improve WLAN security • 802.11j: Modification to comply with Japan • 802.11k: Provide measurement info of APs • 802.11m: Minor Mods to previous Pubs

  13. 802.11 Relatives • 802.11n: Increase WLAN raw throughput • 802.11p: Utilize 5.9 GHz band for Intelligent Transportation System • 802.11o: Faster handoff, prioritize voice traffic over data • 802.11q: Frame tagging for VLAN segregation • 802.11r: Standardize fast-hand-off • 802.11s: Self-healing/self-configuring Mesh networks • 802.11t: Performance prediction

  14. 802.11 Relatives • 802.11d: New Countries • Where 802.11 family not allowed to operate • Specification similar to 802.11b • Main difference, configuration fine-tuned at MAC level to comply with rules of country or district network to operate • Rules subject to variation include allowed: frequencies, power levels, and signal bandwidth

  15. 802.11 Relatives • 802.11e: Quality of Service (QOS) • Goal: Develop QOS technology to help Wi-Fi networks avoid problems when transmitting time-sensitive data like voice and video • One 802.11e innovation starting to be used: frame bursting or packet burning • Improves ratio of data-to-network overhead by sending larger amounts of data in individual frames • Can only speed up mixed 802.11b/802.11g networks • Initial improvement better if all equipment from same manufacturer

  16. 802.11 Relatives • 802.11f: Inter-Access Point Communication • Communication between Wi-Fi APs a problem depending on manufacture • APs will be able to offer fast handoff • Eliminates break in service when roaming • Some features tie with 802.11i security standard • 802.11h: Compatibility with European Regs • Supplementary to MAC layer, comply w/5Ghz WLANs • Require transmission power control (TPC), limits minimum power required to reach furthest user • Require dynamic frequency selection (DFS), selects radio channel at AP to minimize interference with other systems

  17. 802.11 Relatives • 802.11i: Security Specifications • Replaces wired equivalent privacy (WEP) encryption with temporal key integrity protocol (TKIP) • Supplement TKIP with advanced encryption system (AES) • Adds pre-authentication, enables user logged into a corporate-style network connected roaming capability while maintaining connection • Relies on inter-access point communication provided by 802.11f

  18. 802.11 Relatives • 802.11j: 5 GHz Operations in Japan • Main intent, add channels in the RF band of 4.9 GHz to 5 GHz • Implement changes to satisfy Japanese legal requirements concerning: transmitter output power, operational modes, channel arrangements, and spurious emission levels • Like 802.11a networks • Provide speeds up to 54 Mbps • Employ OFDM Transfer Method

  19. 802.11 Relatives • 802.11k: Radio Resource Management • Address lack of standard for managing WLANs • Focuses on two key elements: AP and PC cards • Goal: make measurements from physical and data link layers available to upper layers • Allow upper layers to make decisions about the radio environment and what can be accomplished in that environment • One feature allow better traffic distribution, produce higher speed for the original AP and redirected users

  20. 802.11 Relatives • 802.11m: 802.11 Housekeeping • Perform editorial maintenance, corrections, improvements, clarifications, and interpretations, relative to 802.11 family specification documentation • 802.11n: Inter-access Point Communications • Objective: increase overall and throughput speed of future 802.11 protocols • Real speed 100 Mbps • 250 Mbps in PHY level • 4-5 times faster than 802.11g • 50 times faster than 802.11b • Better operating distance

  21. 802.11 Relatives • 802.11o: Vo Wi-Fi Faster Handoff • A proposed IEEE group to beSpun out of the 802.11i group • Focus for standard for a fast handoff that is fully secure and compatible with 802.11i and Wi-Fi Protected Access (WPA) • Current supported roaming causes brief break in data stream • 802.11i implementation will exacerbate the situation • Handover time (70 milliseconds) make voice calls impossible

  22. 802.11 Relatives • 802.11p: Intelligent Transportation System • Established for wireless access in vehicular environments (WAVE) • Dedicated short range communications (DRC) is a general purpose communications link between the vehicle and roadside (or between vehicles) using 802.11p protocol • Protocols just months old • Improves on dedicated 5.9 GHz range (1,000 ft.) and transmission speed (6 Mbps) • Protocol aimed at vehicles: toll collection, vehicle safety, commerce transactions via cars • Government pushing forward to cover highways with APs that support this new type of extra-secure hotspots that ride over 5.9 GHz • Manufactures expect to install chips, initially in high-end vehicles, in 2007 or 2008 time frame

  23. 802.11 Relatives • 802.11q: VLAN Management • Defines mechanisms for tagging frames, allow them to be segregated into separate VLANs • VLANs extend into WLAN by adding 802.11q awareness to the AP • Frames destined for different VLANs are transmitted by the AP wirelessly on different SSIDs with different WEP keys • Only the client associated with the VLAN receives those packets • Conversely, packets coming from a client associated with a certain VLAN are tagged with 802.11q before they are forwarded into the wired network

  24. 802.11 Relatives • 802.11r: Fast BSS – Transition • Recently founded to address fast roaming among APs • Some experts think technology emerging from 802.11i and 802.11k will render 802.11r group unnecessary • Group still defining scope and does not have a draft yet

  25. 802.11 Relatives • 802.11s: ESS Mesh Networking • Aims to define a MAC and PHY for mesh networks • Improve coverage with no single point of failure • APs relay information hop-by-hop, router like fashion • Adding nodes, scalable and redunant • Can serve as indoor or outdoor networks • Example: Municipalities extend fiber networks or all outdoor enterprises such as construction sites • 802.11t: Wireless Performance Prediction • Enable testing, comparison, and deployment planning of 802.11 WLAN devices • Based on common accepted set of performance metrics, measurement methodologies and test conditions

  26. Wi-Fi Security • Robust Security Network (RSN) • Defined by 802.11i specification • Replaces wired equivalent privacy (WEP) • Backward compatible support of Wi-Fi protected access (WPA) based on temporal key integrity protocol (TKIP) • Uses advanced encryption system (AES) in addition to TKIP • AES method combines a key and a 128-bit block of unencrypted data to produce a block of different encrypted data. • WEP only uses 40-bit key

  27. Wi-Fi Security • 802.11i Standard Acceptance Impact • Business community interest expected to skyrocket in next year or two • Vendors already rolling out firmware enabling 802.11 compliant security protocols • Immediate impact by eliminating VPN infrastructure except when connected remotely, such as a hotel • Performance penalty for 802.11i functionality unknown

  28. Summary • Wireless LAN Applications • Wireless LAN Technology • IEEE 802.11 Standard • IEEE 802.11 Protocol Architecture • IEEE 802.11 Relatives • Wi-Fi Security

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