802.11 standards - wireless networks

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802.11 standards - wireless networks

  1. 1. Wireless Networks
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  3. 3. Wireless Networks - Fundamentals <ul><li>Two Types </li></ul><ul><li>Infrastructural Network </li></ul><ul><ul><li>Client/Server Hierarchy </li></ul></ul><ul><ul><li>BSS – Basic Unit = One AP + One Station </li></ul></ul><ul><li>Ad-Hoc Network </li></ul><ul><ul><li>Peer-to-Peer Scheme </li></ul></ul><ul><ul><li>BSS / IBSS – Basic Unit = Two Stations </li></ul></ul>
  4. 4. Wireless Networks - Fundamentals <ul><li>Infrastructure Model includes: </li></ul><ul><li>(most common) </li></ul><ul><ul><li>Stations (STA) </li></ul></ul><ul><ul><ul><li>any wireless device </li></ul></ul></ul><ul><ul><li>Access Point (AP) </li></ul></ul><ul><ul><ul><li>connects BSS to DS </li></ul></ul></ul><ul><ul><ul><li>controls access by STA’s </li></ul></ul></ul><ul><ul><li>Basic Service Set (BSS) </li></ul></ul><ul><ul><ul><li>a region controlled by an AP </li></ul></ul></ul><ul><ul><ul><li>mobility is supported within a single BSS </li></ul></ul></ul><ul><ul><li>Extended Service Set (ESS) </li></ul></ul><ul><ul><ul><li>a set of BSS’s forming a virtual BSS </li></ul></ul></ul><ul><ul><ul><li>mobility is supported between BSS’s in an ESS </li></ul></ul></ul><ul><ul><li>Distribution Service (DS) </li></ul></ul><ul><ul><ul><li>connection between BSS’s </li></ul></ul></ul>DS BSS1 BSS2 BSS3 STA1 STA2 STA3 ESS1 AP1 AP2 AP3
  5. 5. <ul><li>Ad Hoc Model includes: </li></ul><ul><ul><li>Stations (STA) </li></ul></ul><ul><ul><ul><li>any wireless device </li></ul></ul></ul><ul><ul><ul><li>act as distributed AP </li></ul></ul></ul><ul><ul><li>Independent Basic Service Set (IBSS) </li></ul></ul><ul><ul><ul><li>IBSS forming a self contained network </li></ul></ul></ul><ul><ul><ul><li>no AP and no connection to the DS </li></ul></ul></ul>IBSS STA1 STA2 STA3 Wireless Networks - Fundamentals
  6. 6. <ul><li>Comparison between Ad Hoc and Infrastructure </li></ul><ul><ul><li>Infrastructure mode – </li></ul></ul><ul><ul><ul><li>More stability, scalability, ease of management and improved security </li></ul></ul></ul><ul><ul><li>Ad hoc does not provide security to that level and managing can be difficult incase of network growth. Performance suffers as we increase devices as well. </li></ul></ul><ul><ul><li>Infrastructure mode </li></ul></ul><ul><ul><ul><li>High initial cost to for Access points (routers and switches) </li></ul></ul></ul>Wireless Networks - Fundamentals
  7. 7. Two types of access to air <ul><li>DCF (Distributed Coordination Function ) </li></ul><ul><li> means everybody can speak and try </li></ul><ul><li> to get air : 100% on the market </li></ul><ul><li>PCF (Point Coordination Function) </li></ul><ul><li>means ONE point coordinator (BOSS) </li></ul><ul><li>who will allowed you to speak </li></ul><ul><li>(like in bluetooth) </li></ul>
  8. 8. MAC Classification <ul><li>1. Type of Multiplexing: </li></ul><ul><li>Depending on the dimension used for multiplexing we can classify the MAC layer </li></ul><ul><ul><li>a) Space Division Multiple access(SDMA) </li></ul></ul><ul><ul><li>b) Time Division Multiple access(TDMA) </li></ul></ul><ul><ul><li>c) Frequency Division Multiple access(FDMA) </li></ul></ul><ul><ul><li>d) Code Division Multiple access(CDMA) </li></ul></ul><ul><li>2. Based on Control: </li></ul><ul><li>One can also classify the MAC layer on the basis of the way the control is achieved. </li></ul><ul><li>Centralized -- BSS </li></ul><ul><li>Distributed -- IBSS </li></ul>
  9. 9. MAC Classification <ul><li>Centralized Vs Distributed MAC control </li></ul><ul><li>Centralized </li></ul><ul><li>(+) Easy to design </li></ul><ul><li>(+) Easy management </li></ul><ul><li>(+) Service Differentiation : Giving access according to the priority. </li></ul><ul><li>( - ) Central Bottleneck </li></ul><ul><li>( - ) Single point of failure </li></ul><ul><li>  </li></ul><ul><li>Distributed </li></ul><ul><li>(+) Natural when there is no central information </li></ul>
  10. 10. Goal of Wireless Standards To develop a Medium Access Control (MAC) and Physical Layer (PHY) specification for wireless connectivity for fixed, portable and moving stations within a local area.
  11. 11. Wireless Standards
  12. 12. Wireless Standards <ul><li>Wireless LANs </li></ul><ul><ul><li>Standard is 802.11 </li></ul></ul><ul><ul><li>Also Known as WiFi </li></ul></ul><ul><ul><li>Higher Data Rate </li></ul></ul><ul><ul><li>Longer Distance Coverage – So High Power </li></ul></ul><ul><ul><li>Enhancements </li></ul></ul><ul><ul><ul><li>802.11e – QoS </li></ul></ul></ul><ul><ul><ul><li>802.11i –Security </li></ul></ul></ul><ul><ul><ul><li>802.11n – Throughput </li></ul></ul></ul><ul><ul><ul><li>802.11h – Transmission Power control </li></ul></ul></ul><ul><ul><ul><li>Enhancement – No Explicit Policy, Only facilities will be provided </li></ul></ul></ul>
  13. 13. Wireless Standards <ul><li>Wireless PANs </li></ul><ul><ul><li>Standard is 802.15…….. </li></ul></ul><ul><ul><li>Lower Data Rate </li></ul></ul><ul><ul><li>Shorter Distances – So Low Power </li></ul></ul><ul><ul><li>Enhancements </li></ul></ul><ul><ul><ul><li>802.15.1 – Bluetooth </li></ul></ul></ul><ul><ul><ul><li>802.15.3 – High Data Rate, but Short Range </li></ul></ul></ul><ul><ul><ul><li>802.15.4 – Zigbee – WSN </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Low cost, low power </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Multi functional & More number of devices </li></ul></ul></ul></ul></ul>
  14. 14. Power Consumption in IEEE 802 Wireless Networks
  15. 15. Power Management Techniques <ul><li>Application Layer </li></ul><ul><ul><li>Aimed at scheduling the applications or part of them </li></ul></ul><ul><ul><li>Application Layer Based </li></ul></ul><ul><ul><li>Load Partitioning </li></ul></ul><ul><ul><ul><li>Uses the power from base station </li></ul></ul></ul><ul><ul><li>Proxy based techniques </li></ul></ul><ul><ul><ul><li>Adaptive based on the Power availability </li></ul></ul></ul><ul><ul><li>Applications Based </li></ul></ul><ul><ul><ul><li>Database Techniques </li></ul></ul></ul><ul><ul><ul><li>Video Processing </li></ul></ul></ul>
  16. 16. Power Management Techniques <ul><li>Transport Layer </li></ul><ul><ul><li>Aimed to reduce the number of Retransmissions </li></ul></ul><ul><ul><li>The pa cket loss will not immediately interpreted </li></ul></ul><ul><ul><li>TCP-Probing </li></ul></ul><ul><ul><li>Wave-and-Wait Protocol </li></ul></ul>
  17. 17. Power Management Techniques <ul><li>Network Layer </li></ul><ul><ul><li>Aimed at efficient routing with minimal distance and hops </li></ul></ul><ul><ul><li>Backbone Based - Charge Based Clustering </li></ul></ul><ul><ul><li>Topology Control Based </li></ul></ul><ul><ul><li>Hybrid </li></ul></ul>
  18. 18. Power Management Techniques <ul><li>Network Layer </li></ul><ul><ul><li>Backbone Based - Charge Based Clustering </li></ul></ul><ul><ul><ul><li>Backbone Nodes - Always active </li></ul></ul></ul><ul><ul><ul><li>Hops - Periodically sleep </li></ul></ul></ul>
  19. 19. Power Management Techniques <ul><li>Network Layer </li></ul><ul><ul><li>Topology Control Based </li></ul></ul><ul><ul><ul><li>Reduce the power of overall transmission </li></ul></ul></ul><ul><ul><ul><li>So, power of one hop transmission limited to the range of the nearest neighbor. </li></ul></ul></ul>
  20. 20. Power Management Techniques <ul><li>Data Link Layer - LLC </li></ul><ul><ul><li>Aimed at reducing the transmission overhead </li></ul></ul><ul><ul><li>Two Common Techniques </li></ul></ul><ul><ul><li>Automatic Repeat Request - ARQ </li></ul></ul><ul><ul><ul><li>The router itself enable the retransmission rather than the receiver </li></ul></ul></ul><ul><ul><li>Forward Error Correction – FEC codes </li></ul></ul><ul><ul><ul><li>Reduces the retransmission </li></ul></ul></ul>
  21. 21. Power Management Techniques <ul><li>Data Link Layer - LLC </li></ul><ul><ul><li>Aimed at reducing the transmission overhead </li></ul></ul><ul><ul><li>Packet Scheduling Protocol </li></ul></ul><ul><ul><ul><li>Transmission of Multiple packets </li></ul></ul></ul><ul><ul><ul><ul><li>Burst Mode of Transmission </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Only First packet needs preamble bytes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>All others follow piggyback </li></ul></ul></ul></ul>
  22. 22. Power Management Techniques <ul><li>Data Link Layer - MAC </li></ul><ul><ul><li>Two Common Techniques </li></ul></ul><ul><ul><li>Sleep Scheduling Protocols </li></ul></ul><ul><ul><ul><li>Aimed at reducing the power during ideal listening of channels </li></ul></ul></ul><ul><ul><li>Battery Aware MAC Protocols - BAMAC </li></ul></ul><ul><ul><ul><li>Priority will be given to the Low Charge Node to transmit the packets </li></ul></ul></ul>
  23. 23. Power Management Techniques <ul><li>Data Link Layer - MAC </li></ul><ul><ul><li>Sleep Scheduling Protocols </li></ul></ul><ul><ul><ul><li>Aimed at reducing the power during ideal listening of channels </li></ul></ul></ul><ul><ul><ul><li>Synchronous Sleep Scheduler </li></ul></ul></ul><ul><ul><ul><li>Asynchronous Sleep Scheduler </li></ul></ul></ul>
  24. 24. Power Management Techniques <ul><li>Data Link Layer - MAC </li></ul><ul><ul><li>Sleep Scheduling Protocols </li></ul></ul><ul><ul><ul><li>Synchronous Sleep Scheduler </li></ul></ul></ul><ul><ul><ul><ul><li>Global Clock for all nodes in the set-up </li></ul></ul></ul></ul><ul><ul><ul><ul><li>All nodes are active during “AWAKE” period and inactive during “ASLEEP” </li></ul></ul></ul></ul>
  25. 25. Power Management Techniques <ul><li>Data Link Layer - MAC </li></ul><ul><ul><li>Sleep Scheduling Protocols </li></ul></ul><ul><ul><ul><li>Asynchronous Sleep Scheduler </li></ul></ul></ul><ul><ul><ul><ul><li>No Global Clock for all nodes in the set-up </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Transmitter may start to transmit at any time </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Receiver periodically checks the channel </li></ul></ul></ul></ul>
  26. 26. Power Management Techniques <ul><li>Physical Layer </li></ul><ul><ul><li>Two Common Practices </li></ul></ul><ul><ul><li>Energy Saving </li></ul></ul><ul><ul><ul><li>Remote Access Switch </li></ul></ul></ul><ul><ul><ul><ul><li>Enable the Receiver when only it has the Information </li></ul></ul></ul></ul><ul><ul><li>Energy Harvesting </li></ul></ul><ul><ul><ul><li>Increasing the Energy level from its surroundings </li></ul></ul></ul>
  27. 27. Research Challenges in Power Management Wireless Networks <ul><li>Hardware Level </li></ul><ul><ul><li>Energy Saving </li></ul></ul><ul><ul><li>Energy Harvesting </li></ul></ul><ul><li>Technique / Protocol Level </li></ul><ul><li>Programming Level </li></ul><ul><li>Debate between Hardware and Software </li></ul>
  28. 28. Security in Wireless Networks <ul><li>Authentication – Identification of Anticipated </li></ul><ul><ul><li>There Cases </li></ul></ul><ul><ul><ul><li>User Does Something </li></ul></ul></ul><ul><ul><ul><li>User Has Something </li></ul></ul></ul><ul><ul><ul><li>User Knows Something </li></ul></ul></ul><ul><li>Authorization – Level of Access </li></ul><ul><li>Encryption </li></ul>
  29. 29. Security <ul><li>WEP ( Wired Equivalent Privacy) 64/128 bits </li></ul><ul><li> Using RC4 algorithm, almost permanent key, very week security, able to crack by collecting statistic current security level for 99.9% products on the market. </li></ul><ul><li>TKIP (Temporal Key Integrity Protocol ) </li></ul><ul><li>Used RC4 algorithm with a 128-bit &quot;temporal key&quot; but changes temporal keys every 10,000 packets and key depends on address and sequence number. </li></ul><ul><li>Will be required to obtain WiFi certification from 09/01/03 </li></ul><ul><li>AES (Advanced Encryption Standard ) </li></ul><ul><li>New, much more stronger encryption, protect against hacker frames in insertion. Need hardware accelerator. Optional feature. </li></ul><ul><li>Service Set Identifier (SSID) 802.1X Access Control </li></ul><ul><li>Wireless Protected Access (WPA) IEEE 802.11i </li></ul>
  30. 30. Bandwidth in Wireless Networks <ul><li>Very Peculiar because of a global medium </li></ul>
  31. 31. Addressing in Wireless Networks <ul><li>Traditional addressing – 3 types </li></ul><ul><li>Device addressing </li></ul>
  32. 32. Roadmap of Wireless Standards <ul><li>IEEE 802.11 - The original 1 Mbit/s and 2 Mbit/s, 2.4 GHz RF and IR standard </li></ul><ul><li>IEEE 802.11a - 54 Mbit/s, 5 GHz standard (1999, shipping products in 2001) </li></ul><ul><li>IEEE 802.11b - Enhancements to 802.11 to support 5.5 and 11 Mbit/s (1999) </li></ul><ul><li>IEEE 802.11d - International (country-to-country) roaming extensions </li></ul><ul><li>IEEE 802.11e - Enhancements: QoS, including packet bursting </li></ul><ul><li>IEEE 802.11F - Inter-Access Point Protocol (IAPP) </li></ul><ul><li>IEEE 802.11g - 54 Mbit/s, 2.4 GHz standard (backwards compatible with b) (2003) </li></ul><ul><li>IEEE 802.11h - 5 GHz spectrum </li></ul><ul><li>IEEE 802.11i - Enhanced security </li></ul><ul><li>IEEE 802.11j - Extensions for Japan </li></ul><ul><li>IEEE 802.11k - Radio resource measurement enhancements </li></ul><ul><li>IEEE 802.11n - Higher throughput improvements </li></ul><ul><li>IEEE 802.11p - Wireless Access for the Vehicular Environment (ambulances and passenger cars) </li></ul><ul><li>IEEE 802.11r - Fast roaming </li></ul><ul><li>IEEE 802.11s - Wireless mesh networking </li></ul><ul><li>IEEE 802.11T - Wireless Performance Prediction (WPP) - test methods and metrics </li></ul><ul><li>IEEE 802.11u - Interworking with non-802 networks (e.g., cellular) </li></ul><ul><li>IEEE 802.11v - Wireless network management </li></ul><ul><li>IEEE 802.11w - Protected Management Frames </li></ul>
  33. 33. Roadmap of Wireless Standards Gs Focus Technologies Standards 1G Voice Analog Technology FDMA American Mobile Phone Systems (AMPS) - US Nordic Mobile Telephone (NMT) – Europe Total Access Cellular System (TACS) - UK NTT - Japan 2G Voice Digital Technology TDMA CDMA US TDMA & US CDMA Global System for Mobile GSM) – Europe Pacific Digital System (PDS) - Japan 3G Internet & Multimedia Services to the Mobile Users Digital Technology TDMA CDMA Enhancements of the Above International Mobile Telecommunications 2000 (IMT – 2000)
  34. 34. Roadmap of Wireless Standards Divergence of US and European Standards
  35. 35. Wireless Standards – Present Scenario US and European Standards
  36. 36. Some Comparisons Advantages Disadvantages <ul><li>Mobility </li></ul><ul><li>Ease of Installation </li></ul><ul><li>Flexibility </li></ul><ul><li>Cost </li></ul><ul><li>Use unlicensed part of the radio spectrum </li></ul><ul><li>Roaming </li></ul><ul><li>Interference </li></ul><ul><li>Degradation in performance </li></ul><ul><li>High power consumption </li></ul><ul><li>Low Speed </li></ul><ul><li>Limited range </li></ul><ul><li>Low Reliability </li></ul><ul><li>Low Security </li></ul>
  37. 37. Some Comparisons Wi-Fi Wi-MAX 802.11 802.16 limited in most cases to only 100 - 300 feet (30 - 100m). Provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations. Less Interference More Interference
  38. 38. Some Comparisons 802.11 Wireless LAN Standards Comparison 802.11a 802.11b 802.11g Bluetooth Data Rate (Mbps) 54 11 54 721Kbps 56Kbps Operating Frequency (GHz) 5 2.4 2.4 2.4 Typical power output (mw) 40-800 100 100 100 Compatibility Not compatible with 802.11b or 802.11g Not compatible with 802.11a or 802.11g Compatible with 802.11b Not compatible with 802.11a/b. Range 150feet 150feet 150feet 30feet Interference risk Low High High High Price Expensive Cheap Moderate Moderate Hot-spot access Poor Good Good Poor

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