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Telecommunications in ITS WiFi

Telecommunications in ITS WiFi

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Telecommunications in ITS WiFi

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  1. Telecommunications in ITSWiFi Ing. Martin Šrotýř srotyr@fd.cvut.cz

  2. Access systems CATV Metalic xDSL Fixed PLC Ethernet Optic AON Access network PON WiFi Fixed Wireless WiMAX Nomadic GSM,UMTS Mobile Satelit

  3. Access systems CATV Metalic xDSL Fixed PLC Ethernet Optic AON Access network PON WiFi Fixed Wireless WiMAX Nomadic GSM,UMTS Mobile Satelit

  4. WiFi – IEEE 802.11 WiFi – Wireless Fidelity • First version accepted in 1997 • Range up to several kilemetrs (directional antenna, direct visibility,…) • Network configuration: • ad-hoc (p2p) • infrastructure • Main standards 802.11 a / b / g / n / p • Additional standards 802.11 f / i / r / …

  5. IEEE 802.11 – standard summary

  6. IEEE 802.11b Approved in 1999, CTO authorized this standard to use in 2000 2,412 – 2,472 GHz (60 MHz) 13 channels with intervals of 5 MHz, channel width is about 22 MHz Max. transfer rate 11 Mbit (11, 5,5, 2, 1 Mbit/s) Ad-hoc (P2P), Infrastructure DSSS (Direct Sequence Spread Spectrum) 30 – 40 % of capacity is used by the 802.11 protocol

  7. IEEE 802.11b 802.11b channel width

  8. IEEE 802.11b/g Schematic distribution of 802.11b/g channels

  9. 2,4 GHz channels

  10. IEEE 802.11a Approved in 1999, CTO (Czech Telecommunication Office) authorized this standard to use in september 2005 5,470 – 5,725 GHz (255 MHz) 11 non-overlapping channels with intervals of 20 MHz Max. transfer rate 54 Mbit (54,48,36,24,18,12,9,6 Mbit/s) Ad-hoc (P2P), Infrastructure OFDM (Orthogonal Frequency Division Multiplexing) BPSK, QPSK, 16-QAM, 64-QAM

  11. 5 GHz channels INDOOR OUTDOOR

  12. IEEE 802.11g • Approved in 2003, CTO authorizedthis standard to use in 2000 • 2,412 – 2,472 GHz (60 MHz) • 13 channelswithintervalsof 5 MHz, channelwidthisabout 22 MHz • OFDM a DSSS (forcompatibilitywith 802.11b) • Max. transfer rate 54 Mbit OFDM: 16-QAM (54, 48, 36, 24 Mbit/s) QPSK (18, 12 Mbit/s) BPSK (9, 6 Mbit/s) DSSS: (11, 5,5, 2, 1 Mbit/s)

  13. IEEE 802.11n Approved on 11.9.2009 2,4 GHz, 5 GHz with 20 and 40 MHz channels Compactibility with 802.11a/b/g MIMO technology (Multiple Input Multiple Output) Available max. transfer rate 300 Mbit (Draft 2.0) Max. data rate up to 600 Mbit (4 spatial streams, 64-QAM 5/6, 40 MHz channels, short guard interval) 13

  14. IEEE 802.11n 14

  15. IEEE 802.11n – 40 MHz in 2,4 GHz 15

  16. IEEE 802.11p Approved in November 2010 ??? WAVE (Wireless Access for the Vehicular Environment) Licensed band 5,9 GHz For road safety application and inter-vehicle, infrastructure communications For speeds up to 200 km/h Max. transfer rate 27 Mbit/s Range up to several km Cooperation with CALM, DSRC

  17. IEEE 802.11 – architecture

  18. IEEE 802.11 – MAC layer – DCF CSMA/CA (CarrierSense Multiple Access withCollisionAvoidance) RTC/CTS (Request To Send / Clear To Send)

  19. IEEE 802.11 – MAC layer – PCF Rarelyimplemented, small support, thereis no choiceofpriorities Broadcastingstationsbroadcast „beacon“ framcesatfixedintervals (0,1s) CP (Contention Period) – DCF system CFP (Contention Free Period) – PCF systemIsdirectlydeterminedwhichclient has theright to broadcast, theother are forbidden to broadcast

  20. IEEE 802.11e – Wireless QoS Approved in 2005 Adds support for QoS Implements a class of traffic 3 phase certificationWMM – 2004 (EDCA)WMM-PS – 2005 (EDCA)WMM-SA – ? (EDCA, HCCA) Still based on collision approach

  21. IEEE 802.11e – Wireless QoS EDCAPriorities according to 802.1d4 traffic category 8 priority classes HCCASimilarly to PCFTwo sections – CAP (CFP) a CPCAP (Controlled Acces Phase) – initiated anytime by access pointPreference according to priority classesQueuing priorities + reporting informations about queues

  22. IEEE 802.11i – WPA2 Wireless Protected Access Approved in 06/2004 Significantly improves security (compared to the original WEP) Uses a block cipher AES Implemented protocols CCMP – provides confidentiality, integrity and authenticationTKIP – provides the combination of keys for packets, checking the integrity of messages and key exchange mechanism

  23. IEEE 802.11r Fast roaming Aprroved in September 2008 Cooperation with 802.11i Multilevel hierarchy, WLAN controller Ensuring the handover with WPA2 in units of ms vs. specialized software

  24. IEEE 802.11 – equipment Antenna - omnidirectional, sector, directional Frequency, gain, polarization, pattern

  25. IEEE 802.11 – equipment Antenna - omnidirectional, sector, directional Frequency, gain, polarization, pattern

  26. IEEE 802.11 – equipment Active elemets Interface (USB, Ethernet, miniPCI, PCI, ExpressCard, …) Supported standards, modes, …

  27. Thank you for attention.