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IEEE 802.11 Concepts

IEEE 802.11 Concepts. 資工碩職一 492515174 周俊弘. Introduction. Overview of the Emerging 802.11 Standard 802.11 Architecture DSSS v.s. FHSS OFDM Modulation Reference. IEEE 802.11. 802.11 MAC and PHY spec., 1/2 Mbps in 2.4 GHz band 802.11a OFDM, 6/9/12/18/25/36/48/54 Mbps, in 5 GHz band

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IEEE 802.11 Concepts

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  1. IEEE 802.11 Concepts 資工碩職一 492515174 周俊弘

  2. Introduction • Overview of the Emerging 802.11 Standard • 802.11 Architecture • DSSS v.s. FHSS • OFDM • Modulation • Reference

  3. IEEE 802.11 • 802.11 MAC and PHY spec., 1/2 Mbps in 2.4 GHz band • 802.11a OFDM, 6/9/12/18/25/36/48/54 Mbps, in 5 GHz band • 802.11b Higher Speed, 5.5/11Mbps, in 2.4 GHz band (CCK modulation) • 802.11d 802.11 MAC Bridge On-going: • 802.11e enhanced MAC for supporting QoS • 802.11DS Inter-Access Point Protocol (IAPP) across a Distribution System • 802.11h Dynamic Channel Selection and Transmit Power Control in 5 GHz • 802.11g mandatory: CCK (11Mbps)/OFDM (upto54Mbps) in 2.4 GHz band optional: CCK/PBCC-22M, CCK/OFDM • 802.11i enhanced MAC for improvements in security • 802.11f Inter-Access Point Protocol

  4. ISM Unlicensed Frequency band

  5. Current Popular Wireless Technology Comparison

  6. GLOBAL SPECTRUM ALLOCATION AT 2.4GHz • Frequency band of operation: 2.400 Ghz ~ 2.483 Ghz unlicensed • Globally represented *Nor America:FCC part 15.247 - 15.249 *Europe:ETS 300 – 328 *Japan:RCR-STD-33A

  7. Comparison of Next Generation WLANs

  8. IEEE802.11 WLAN Standards • Support three (3) Physical (PHY) layer type:DSSS,FHSS,Infrared Light (IR). • Medium Access Control (MAC) sublayer • Support peer to peer(Ad Hoc) & infrastructure • High data rata extension using existing MAC layer • Provides reliable,efficient Wireless data networking • Robust against interference

  9. IEEE802.11 WLAN Standards • Short Description of the Standards: IEEE Std 802.11-1997 specifies a single Medium Access Control (MAC) sublayer and 3 Physical Layer Specifications. • Signle MAC • Three PHYs •DSSS: This PHY provides both 1 and 2Mbit/s operation. The 1Mbit/s version uses Differential Binary Phase Shift Keying (DBPSK) and the 2Mbit/s version uses Differential Quadrature Phase Shift Keying (DQPSK). •FHSS: This PHY provides for 1Mbit/s (with 2Mbit/s optional) operation. The 1Mbit/s version uses 2 level aussian Frequency Shift Keying (GFSK) modulation and the 2Mbit/s version uses 4 level GFSK. •Infrared: This PHY provides 1Mbit/s with optional 2Mbit/s. The 1Mbit/s version uses Pulse Position Modulation with 16 positions (16-PPM) and the 2Mbit/s version uses 4-PPM

  10. Why Spread Spectrum Technology ? • Immunity of interference and jamming • Immunity of multi-path fading (typical indoor environment) • Low detectability / probability of intercept • Message privacy • Multiple access via Code-Division (CDMA)

  11. What are the Spread Spectrum Signals? • Tx Rx

  12. DSSS • Data rates 5.5 Mbps and 11 Mbps.

  13. FHSS • Data rates 1 Mbps and 2 Mbps. • Carrier Hops Every 400ms (IEEE 802.11 Standard)

  14. DSSS v.s. FHSS .

  15. modulation

  16. modulation

  17. Reference • IEEE Std 802.11a-1999 (Supplement to IEEE Std 802.11-1999) • IEEE Std 802.11b/D8.0, Sept 2001 (Draft Supplement to IEEE Std 802.11 1999 Edition) • IEEE 802.11 Tutorial by Jim Zyren and AI Petrick • IEEE 802.11 Wireless LAN:Can We Use It for Multimedia? Editor: Peiya Liu • CWNA EXAM PW0-100

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