Public Wireless LAN Service touch@coe.psu.ac.th
Radio Wave
Wave Frequency Amplitude Wave Length
Radio Wave Band Frequency Wavelength VLF 3-30 khz > 10 km LF 30-300 khz 1-10 km MF 300-3,000 khz 100-1000 m HF 3-30 MHz 10-100 m VHF 30-300 MHz 1-10 m UHF 300-3,000 MHz 10-100 cm SHF 3-30 GHz 1-10 cm EHF 30-300 GHz 1-10 mm
ISM Band Industrial, Scientific, and Medical Define by ITU-R Anyone can use Subject to Local usage policy
Well Known ISM Band 2450 MHz band for Bluetooth 5800 MHz band for HIPERLAN 2450 MHz and 5800 MHz band for IEEE 802.11 2450 MHz band for Microwave Oven 915 MHz, 2450 MHz and 5800 MHz for Cordless Phone 13.56 MHz for RFID devices
2.4 GHz Wifi Channels
Wireless Technologies Wireless LAN (IEEE 802.11) Wireless PAN (IEEE 802.15) Wireless Broadband (IEEE 802.16)
Wireless LAN Standards
Wireless LAN Standards 802.11
Wireless LAN Standards 802.11 802.11b
Wireless LAN Standards 802.11 802.11b 802.11a
Wireless LAN Standards 802.11 802.11b 802.11a 802.11g
Wireless LAN Standards 802.11 802.11b 802.11a 802.11g 802.11n
IEEE 802.11 Bitrate 1 or 2 Mbps + FEC code Running on 2.4 GHz ISM Band Direct Sequence Spread Spectrum (DSSS)
IEEE 802.11b Running on 2.4 GHz ISM Band Usually running in 11 channel range Provide up to 11 Mbps raw data rate Backward Compatible with 802.11 (DSSS) May caused interference with other devices
IEEE 802.11g Running on 2.4 GHz ISM Band Up to 54 Mbps raw data rate Typically 20 Mbps througthput Physical Signal Modulation OFDM with CCK Backward compatible with 802.11 and 802.11b
IEEE 802.11a Running on 5 GHz ISM Band Less Crowded Effective range is less than 2.4 GHz Provide Bitrate up to 54 Mbps Not available in some country (e.g., Thailand) OFDM
IEEE 802.11n Available on 2.4 GHz and 5 GHz ISM Band Multiple-Input Multiple-Output (MIMO) Backward compatible with 802.11a (5 GHz) and 802.11b/g (2.4 GHz) OFDM
Wireless NIC
Wireless NIC
Wireless NIC
Wireless Access Point
Wireless LAN Network
2.4 GHz Wifi Channels
Wireless LAN Network
Wireless LAN Network 1
Wireless LAN Network 1 6
Wireless LAN Network 1 11 6
Wireless LAN Network 1 11 6 1
Wireless LAN Network 1 11 6 6 1
Roaming
Hidden Node Problem
Exposed Terminal Problem
IEEE 802.3 Frame Types
IEEE 802.3 Frame Types Management Frames
IEEE 802.3 Frame Types Management Frames Association Request
IEEE 802.3 Frame Types Management Frames Association Request Association Response
IEEE 802.3 Frame Types Management Frames Probe Request Association Request Association Response
IEEE 802.3 Frame Types Management Frames Probe Request Probe Response Association Request Association Response
IEEE 802.3 Frame Types Management Frames Probe Request Probe Response Association Request Association Response Beacon
IEEE 802.3 Frame Types Management Frames Probe Request Probe Response Beacon Authentication Association Request Association Response
IEEE 802.3 Frame Types
IEEE 802.3 Frame Types Control Frames
IEEE 802.3 Frame Types Control Frames Request to send (RTS)
IEEE 802.3 Frame Types Control Frames Request to send (RTS) Clear to send (CTS)
IEEE 802.3 Frame Types Control Frames Request to send (RTS) Clear to send (CTS) Acknowledgement
IEEE 802.3 Frame Types Control Frames Acknowledgement Data Frames Request to send (RTS) Clear to send (CTS)
Adaptive Rate Selection
Authentication and Association Types
Authentication and Association Types Unauthenticated and Unassociated
Authentication and Association Types Unauthenticated and Unassociated Authenticated and Unassociated
Authentication and Association Types Unauthenticated and Unassociated Authenticated and Unassociated Authenticated and Associated
Radio Wave
Radio Modulation
Omni Directional Antenna
Omni Directional Antenna
Omni Directional Antenna
Directional Antenna
Signal-to-Noise (SNR) ratio Signal (db) - Noise (db) >40dB SNR = Excellent 25-40 db SNR = Very good 15-25 db SNR = Log signal 10-15 db SNR = Very low signal 5-10 db SNR = No signal, not association
Directional Antenna
CAntenna
Wireless Security
Wireless Security Open Authentication
Wireless Security Open Authentication Wired Equivalent Privacy (WEP)
Wireless Security Open Authentication Wired Equivalent Privacy (WEP) Wi-Fi Protected Access (WPA)
Lab
http://mamboeasy.psu.ac.th/ ~wiboon.w/content/view/58/40/
Wireless LAN Installation Site Survey Installation
Wireless LAN Site Survey Tools Airmagnet Ekahau site Survey Netstumbler
Site Survey Consideration Understand the wireless requirement Obtain a facility diagram Visual inspect the facility Identify coverage areas Verify access point locations Document findings Access existing network infrastructure Determine preliminary access point locations