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  • This section discusses theories and processes of using Spred Spectrum technology to send data over an RF signal. Spread Spectrum is a type of emission designed to be somewhat immune to interference, difficult to detect, and hard to intercept. Actress Hedy Lamarr and music composer George Antheil patented the concept of Spread Spectrum in 1942. The idea was a method for guiding a torpedo without interference from a jamming signal. In 1986, the FCC agreed to allow the use of Spread Spectrum in the commercial market under the ISM bands. Just as the radio in your car has AM (Amplitude Modulation) and FM (Frequency Modulation) bands, other radios use different bands and types of modulation.
  • Assuming a 6 dBi antenna (The radiated power is): UNII-1 – 50 mW in the US/Japan, 200mW in Europe, 4 Channels (5.15-5.25), Indoor Access- Fixed Antenna UNII-2 – 250 mW in US, 4 Channels (5.25-5.35)- Indoor/Outdoor Use – Flexible Antenna UNII-3 – 1 W in the US, 4 Channels (5.725-5.825) – Outdoor Bridging only HiperLAN – 200 mW in Europe, 8 Channels (5.25-5.35) – Indoor Use only HiperLAN– 1W in Europe, 11 channels (5.470-5.725) – Indoor/Outdoor Use –Flexible Antenna
  • The Site Survey utility allows a user to perform a site survey to determine the best placement of the access points in order to provide the desired coverage. The Site Survey can run in either Passive or Active mode. The Active mode is used to perform site surveys. The Site Survey utility can be set to display results as percentages, or as actual values (for example, as dBm, or decibels per milliwatt). Complete the following steps to switch from percentage to dBm. 1. Click on the Preferences icon on the main page. 2. Select the dBm radio button under Signal Strength Display Units . Now your ACU Site Survey will show signal to noise ratio.

FWL_v11_Mod02.ppt FWL_v11_Mod02.ppt Presentation Transcript

  • © 2003, Cisco Systems, Inc. All rights reserved.
  • Module 2 IEEE 802.11 and Network Interface Cards
  • Learning Objectives
      • Identify the IEEE 802. standards.
      • Identify the IEEE 802.11 standards.
      • Understand the MAC and PHY layers of 802.11
      • Identify which client operating systems are supported.
      • Determine the status of a client card by observing the indicator lights.
      • Install and configure a Cisco Aironet PC Card.
  • Overview
      • This chapter will cover the IEEE 802.11 WLAN (WLAN) standards in detail, including data link and physical layer specifications. Throughout this module and this course, the terms IEEE and 802 are used often. This module provides a short overview of IEEE and the 802 committee. The MAC and physical layer services that have been standardized will be discussed. Finally, client adapters, driver types, and client support will also be discussed.
  • Key terms
    • IEEE
    • MAC
    • PHY
    • NIC
    • STA
    • MSDU
    • PLCP
    • PMD
    • BSS
  • 802.11 Standards
  • IEEE 802.11 Standards Activities
    • 802.11a: 5GHz, 54Mbps
    • 802.11b: 2.4GHz, 11Mbps
    • 802.11d: Multiple regulatory domains
    • 802.11e: Quality of Service (QoS)
    • 802.11f: Inter-Access Point Protocol (IAPP)
    • 802.11g: 2.4GHz, 54Mbps
    • 802.11h: Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC)
    • 802.11i: Security
    • 802.11j: Japan 5GHz Channels (4.9-5.1 GHz)
    • 802.11k: Measurement
    • 802.11m: Maintenance
    • 802.11n: High-Speed
  • 802.11a / 5 GHz Band
    • Data rates supported: 54, 48, 36, 24, 12, and 6 Mbps
      • Client will automatically “downshift” to lower data rate when it gets further from AP
    • 23 Countries have approved the use of 802.11a products:
      • U.S. Australia Austria Denmark France Sweden New Zealand Ireland Japan Singapore Taiwan Argentina
      • U.K. Germany Norway Portugal Canada Belgium Netherlands Finland Poland Switzerland Mexico
    • 802.11h will ultimately permit worldwide usage of WLANs @ 5 GHz
      • Transmit Power Control (TPC)
      • Dynamic Frequency Selection (DFS)
    • 5.470-5.725 GHz band being opened up (11 more channels)
      • This new 5.47-5.725 GHz band, plus 5.25-5.35 GHz UNII-2 band, will require DFS
      • Current UNII-2 products in the market will likely be grandfathered (i.e. no DFS)
    • 5 GHz band has more channels than 2.4 GHz band
      • UNII-1 + UNII-2 = 8 channels (plus 11 future channels) vs. 3 channels for 2.4 GHz
      • However, depending on distance between AP’s, you may only be able to use half of the 5 GHz channels due to adjacent channel interference
    • 5 GHz band subject to less interference than 2.4 GHz band
      • However, 2.4 GHz interference not a major problem in most business environments
  • Three Wireless Technologies The Laws of Radio Dynamics: Higher Data Rates = Shorter Transmission Range Higher Power Output = Increased Range, but Lower Battery Life Higher Frequency Radios = Higher Data Rates Shorter Ranges 802.11 b 802.11 a 802.11 g 2.4 GHz 5 GHz 2.4 GHz Worldwide US/AP Worldwide 11 Mbps 54 Mbps 54 Mbps Frequency Band Availability Maximum Data rate Other Services (Interference) Cordless Phones Microwave Ovens Wireless Video Bluetooth Devices Cordless Phones Microwave Ovens Wireless Video Bluetooth Devices HyperLAN Devices
  • IEEE 802.11 Standard
    • IEEE 802.11 became a standard in July 1997
      • 2.4 GHz at 2 Mbps Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS)
    • IEEE 802.11a and 802.11b became standards in September 1999
      • 802.11a – 5 GHz at 54 Mbps OFDM
      • 802.11b – 2.4 GHz at 11 Mbps DSSS
    • IEEE 802.11g is scheduled to be ratified in 2003
      • 802.11g – 2.4 GHz at 54 Mbps OFDM
    • 802.11 promises “true” vendor interoperability
  • Standards and Organizations
  • WLAN Speeds & Frequencies 802.11g 2.4 GHz – OFDM/CCK 54 Mbps Proprietary
    • IEEE 802.11a/b Ratified
    802.11a 5 GHz – OFDM 54 Mbps 802.11b 2.4 GHz – CCK 11 Mbps Jan’99 Jan’00 Jan’01 Jan’02 Jan’03 Jan’04
  • What Is WLAN RF Technology?
    • Data sent over the air waves
    • Two-way radio communications (half duplex)
    • Same radio frequency for sending & receiving (transceiver)
    • No licensing required for Cisco Aironet Wireless products (in most countries)
  • IEEE 802. Standards
  • 802.11 Architecture
  • 802.11 Physical (PHY) Layer Modulations
  • Stations (STA)
  • PHY Protocols
  • Basic Service Set (BSS)
  • Independent Basic Service Set (IBSS)
  • Extended Service Set (ESS) and Distributed System (DS)
  • MAC Layer
  • MAC Services
  • MAC Architecture
  • CSMA
  • Interframe Spaces
  • PHY Layer
  • PHY Functions
  • 802.11b
  • 2.4 GHz Channel Sets Americas Europe, Middle East and Asia 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Center Frequency 2412 MHz 2417 MHz 2422 MHz 2427 MHz 2432 MHz 2437 MHz 2442 MHz 2447 MHz 2452 MHz 2457 MHz 2462 MHz 2467 MHz 2472 MHz 2484 MHz Japan Israel X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Regulatory Domain Channel Identifier
  • Channels- 2.4 GHz DSSS
    • 11 “chips per bit” means each bit sent redundantly
    • 11 Mbps data rate
    • 3 access points can occupy same area
    11 Channels – each channel 22 MHz wide 1 set of 3 non-overlapping channels 14 Channels – each channel 22 MHz wide 4 sets of 3 non-overlapping channels, only one set used at a time
  • 802.11b Access Point Coverage 1 Mbps DSSS 5.5 Mbps DSSS 11 Mbps DSSS 2 Mbps DSSS
  • 802.11b Scalability Blue = 11 Mbps Green = 11 Mbps Red = 11 Mbps Total Theoretical Bandwidth = 33 Mbps
  • Comparing the Technologies 802.11a Data Rates Modulation with Sub Channels BPSK Data Rate Per Subchannel (Kbps) BPSK QPSK 125 187.5 250 QPSK 375 Total Data Rate (Mbps) 6 9 12 18 16QAM 16QAM 64QAM 500 750 1000 64QAM 1125 24 36 48 54
  • 802.11a Channel Sets Americas (-A) Japan (-J) Singapore (-S) Taiwan (-T) 34 5170 x 36 5180 x x 38 5190 x 40 5200 x x 42 5210 x 44 5220 x x 46 5230 x 48 5240 x x 52 5260 x x 56 5280 x x 60 5300 x x 64 5320 x x 40 40 20 40 Channel Set Cisco Maximum Peak Power (mW)* Channel ID Frequency (MHz) Americas include: Argentina Australia Austria Brazil Canada Chile Columbia Denmark France Mexico New Zealand Panama Peru Sweden United Kingdom United States Venezuela
  • 802.11a Access Point Coverage OFDM 54 Mbps 48 Mbps 36 Mbps 24 Mbps 18 Mbps 12 Mbps 09 Mbps 06 Mbps
  • 802.11a Scalability (Indoor UNII-1 and 2) 54 Mbps 54 Mbps 54 Mbps Total Theoretical Bandwidth = 432 Mbps 8 non-overlapping channels 54 Mbps 54 Mbps 54 Mbps 54 Mbps 54 Mbps
  • Client Adapters
  • Cisco Aironet 802.11b Client Adapters
    • 2.4 GHz
      • 802.11b
      • 11 Mbps
    • Include
      • PC Card
      • PCI Card
      • LMC Card
      • Mini PCI
  • 802.11b PC Card
    • 2.4 GHz/802.11b
      • 11 Mbps
    • Rate Shifting
      • 1, 2, 5.5, and 11Mbps
    • Fixed data rates
      • User configurable option
    • Integrated Antenna
    • PCMCIA interface
    • Transmit power settings:
      • 100 mW, 50 mW, 30 mW, 20 mW, 10 mW, 5 mW, and 1 mW
  • 802.11b LMC Card
    • 2.4 GHz/802.11b
      • 11 Mbps
    • Rate Shifting
      • 1, 2, 5.5, and 11Mbps
    • Fixed data rates
      • User configurable option
    • PCMCIA interface
    • Transmit power settings:
      • 100 mW, 50 mW, 30 mW, 20 mW, 10 mW, 5 mW, and 1 mW
  • 802.11b PCI Card
    • 2.4 GHz/802.11b
      • 11 Mbps
    • Rate Shifting
      • 1, 2, 5.5, and 11Mbps
    • Fixed data rates
      • User configurable option
    • RP-TNC Connector
    • PCMCIA interface
    • Transmit power settings:
      • 100 mW, 50 mW, 30 mW, 20 mW, 10 mW, 5 mW, and 1 mW
  • 802.11b Mini PCI Adapter
    • 2.4 GHz/802.11b embedded wireless for notebooks
    • 100 mW transmit power
    • Must order through PC manufactures (not orderable directly through Cisco)
  • 802.11a CardBus2 Client Adapter
    • 5 GHz/802.11a
      • 54 Mbps
    • Rate Shifting
      • 6, 9, 12, 18, 24, 36, 48, or 54
    • Fixed data rates
      • User configurable option
    • 5 dBi Patch Antenna
    • CardBus interface
    • Transmit power settings:
      • 20 mW, 10 mW, and 5 mW
  • PC Card LEDs
    • Dual LED helps identify the card status
    • Green LED is the Status LED
    • Orange LED is the RF traffic LED
  • LED Status
  • Windows Drivers
  • Linux and Macintosh Drivers
  • Downloading Drivers and Software
  • Ad-Hoc
  • Infrastructure
  • Aironet Client Utility: Main Screen
  • Aironet Client Utility: Loading Firmware
  • Aironet Client Utility: Profile Manager
  • Aironet Client Utility: Adding a Profile
  • Profile: System Parameters
  • Profile: RF Network
  • Profile: RF Network
  • Profile: Advanced (Infrastructure)
  • Profile: Advanced (Ad Hoc)
  • Profile: Network Security
  • Aironet Client Utility: Status
  • Aironet Client Utility: Statistics
  • Aironet Client Utility: Link Test
  • Aironet Client Utility: Site Survey
  • Link Status Meter
  • Installing the Client Adapter
    • Insert the adapter card into the PCMCIA slot in the PC
  • Task 4: ACU Install and Setup From the UTILS folder on the driver CD, run SETUP SETUP
  • Task 4: ACU Install and Setup (cont.)
  • Task 4: ACU Install and Setup (cont.)
  • Task 4: ACU Install and Setup (cont.)
  • Task 4: ACU Install and Setup (cont.)
  • Task 4: ACU Install and Setup (cont.)
    • Aironet Client Utility (ACU)
  • Task 4: ACU Install and Setup (cont.) Step 12 Step 13 Step 14
  • Task 4: ACU Install and Setup (cont.) Step 16 Step 17
  • Summary
      • Identify characteristics of Cisco Aironet 802.11a products.
      • Identify characteristics of Cisco Aironet 802.11b products.
  • © 2003, Cisco Systems, Inc. All rights reserved.