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IEEE 802.11 Concepts

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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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