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Indoor Wireless LAN (System Overview)

Indoor Wireless LAN (System Overview). Contents. Network diagrams System elements Standards Spectrum usage Technology Key System Features. Stand alone Wireless LAN - any to any. Laptop PC with PC Card. Laptop PC with PC Card. Desktop PC with USB adapter.

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Indoor Wireless LAN (System Overview)

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  1. Indoor Wireless LAN (System Overview)

  2. Contents • Network diagrams • System elements • Standards • Spectrum usage • Technology • Key System Features

  3. Stand alone Wireless LAN - any to any Laptop PC with PC Card Laptop PC with PC Card Desktop PC with USB adapter

  4. Stand alone Wireless LAN - With Access Point Access Point Laptop PC with PC Card Laptop PC with PC Card Desktop PC with USB adapter

  5. Stand alone Wireless LAN (SOHO, connected to Internet) Desktop PC with USB adapter and shared printer Broadband Gateway Laptop PCs with PC Card

  6. Enterprise network (Printer) Server Gateway server Access Point Access Point

  7. Contents • Network diagrams • System elements • Standards • Spectrum usage • Technology • Key System Features

  8. System elements - PC Cards • PC Card with integrated antenna for laptops • IEEE 802.11b (ORiNOCO) PC Card • PCMCIA Type 2 compliant • WiFi compliant • Data-rates up to 11 Mbps • Operates in 2.4 GHz ISM band • Based on Agere Systems design • Provides connector for range extender • IEEE 802.11a (Harmony) PC Card • Cardbus compliant • Data-rates up to 54 Mbps • Can double data-rate to 108 Mbps (not IEEE 802.11a compliant) • Operates in 5 GHz ISM band • Based on Atheros reference design

  9. System elements - PCI Adapter • Embedded solution for desktop computers Two products available: • PCI-to-PCMCIA bridge card • Adapter card that provides PCMCIA socket to desktop PC • Requires wireless PC Card to operate as wireless station • Operates on PCMCIA cards only • Can use other PCMCIA cards than wireless PC Cards • Wireless PCI adapter • Network card with wireless PC card attached to it • Works as real NIC • Card is locked in position

  10. System elements - Mini PCI Adapter • MiniPCI Type IIIA Form Factor • For use by PC Vendors for integration in laptops • Design by Agere Systems • Antenna Integrated in OEM Notebook. • 4 versions: • Antenna diversity & 64 WEP • Antenna diversity & 128 RC4 • No antenna diversity & 64 WEP • No antenna diversity & 128 RC4

  11. System elements - USB Client Adapter • desk-top unit with integrated wireless PC Card, to connect to USB port of client station • Includes ORiNOCO PC Card (World card). • Software driver support for Windows 98 and Windows 2000 (NDIS5 Miniport Driver) • Compliant with ORiNOCO Client Manager (Diagnostic Utility)

  12. System elements - Indoor Range Extender Antenna • For ORiNOCO PC Cards • Antenna diversity • Omni-directional • Provides 2.5 dBi gain • Cable length 1.5 Meter • Table stand or wall mounted

  13. System elements - Access Points • Ethernet MAC Bridge • Connects wireless stations to Ethernet • Handles roaming stations Different models for different needs: • AP-200 • Low end model meant for SME market • Single embedded PC Card • AP-500 • Small Enterprise model • Single PC Card • Active Ethernet ready • AP-1000 • Will be phased out (replaced by AP-2000) • AP-2000 • Dual slot AP • 2.4GHzand 5 GHz support

  14. System elements - Access Points comparison

  15. System elements - Power over LAN (Active Ethernet) • Power-Over-LAN Hub is the means for adding power to premise cabling that is also being used to carry Ethernet. Products: • 12 port injector • 6 port injector • 1 Port Injector • splitter for AP-1000 and AP-2000 (AP500 is AE-ready)

  16. Network Layer IEEE: LLC Layer IEEE: MAC Layer Physical Layer System elements - Client driver software • Drivers for ORiNOCO PC Card, PCI adapter, USB Adapter and Mini PCI Card • Windows 3.xx (NDIS, ODI) • Windows 95 driver • Windows NT4 driver • Windows 98/ME/2000 • Windows/XP • Linux • Apple (G3) Powerbook • Windows/CE • DOS (packet) drivers

  17. System elements - Client station diagnostic utility software • Utilities that allow the client station to configure its PC card and monitor the quality of the connection • ORiNOCO Client Manager • Works with ORiNOCO PC Cards • Includes: • Link test • Site Monitor • History test • Support for user defined profiles • Harmony utility • Works with 802.11a PC Cards • Includes: • Support for user defined profiles • Signal strength test • Snoop tool • Statistics monitor

  18. System elements - Client Station Supplicant SW (802.1x) • To provide “supplicant” support for Windows versions that do not include a supplicant • Windows/XP includes a supplicant provided by Microsoft • Older Windows OS-es do not include a Microsoft supplicant • Supplicants are available and provided by: • Funk Software • Meeting House Communications

  19. AP systems Router Router Backbone System elements - AP Management tools • AP-500 and AP-1000 managed through windows based “AP Manager”: • Configuration • Monitor AP units • Upgrade AP firmware • Remote link test between AP and associated client • AP-200 and AP-2000 managed through: • Web browser • Command Line Interface (Telnet or Serial communications) • All APs manageable through WiLMA (Wireless LAN Manager) • SNMP based • Manages a large number of APs from single location • Allows group operation (single command on multiple APs)

  20. Contents • Network diagrams • System elements • Standards • Spectrum usage • Technology • Key System Features

  21. Standards - IEEE 802.11 (What is it) • Standard for Wireless Local Area Networks • Optimized specifically for wireless LANs • Designed by large consortium of major industry players • Multi-vendor interoperability over the same physical media Medium Access Control (MAC) the protocol the transmitters and receivers DSSS PHY FHSS PHY IR PHY

  22. Standards - IEEE 802.11 (the base) • Available since August 1999 (first ratified version June 1997) • Defines • MAC protocol • IR PHY • Spread Spectrum in 2.4 GHz band • FHSS PHY • Data rate (1 and 2 Mbps) • Modulation (2 and 4 level GFSK) • Hop sequences • DSSS PHY • Data rate (1and 2 Mbps) • Modulation (DBPSK and DQPSK) • Channels per regulatory domain

  23. Standards - IEEE 802.11b (high speed extension for 2.4 GHz) • Drafted • Defines • High speed (> 2 Mbps) • 2.4 GHz band • Modulation (BPSK, QPSK, with CCK) • Data rates (5.5, 11 Mbps) • Channels per domain (Up to 13) • Implemented in ORiNOCO 11Mbps

  24. Standards - IEEE 802.11a (high speed extension for 5 GHz) • Drafted • Defines: • Speeds up to 54 Mbps • Spectrum usage in 5 GHz band (lower and middle U-NII bands) • Up to 12 channels • Data-rates 54, 48, 36, 24, 18, 12, 6 Mbit/s • OFDM Modulation with 64 QAM, 16 QAM, QPSK, BPSK • Implemented in • 5GHz kit for AP-2000 • Harmony PC Card • FCC regulations prohibit use of external antennae: • No connector on radio card • Antenna fixed to the radio

  25. Integral antennas only Standards - HiperLAN • Restricts usage of IEEE 802.11a products as there differences between HiperLAN allowed operation and IEEE 802.11a • With limitations IEEE 802.11a can be used under HiperLAN rules: • HiperLAN does not allow use of the high U-NII band • HiperLAN requires TPC (Transmit Power Control) • HiperLAN requires DFS (Dynamic Frequency Selection)

  26. Standards - IEEE 802.1x (Port Based Access Control) • IEEE 802.1x - Port Based Network Access Control • Standard to address the requirement to restrict access to LANs (and their connected services) to those users that are permitted to use the LAN • Still in draft (version 11 is out for working-group comments) • Primary focus is authentication of wired ports, extended to apply to wireless • Uses Extensible Authentication Protocol (PPP-EAP, defined in RFC) and applies it over LAN • Standard addresses Authentication and not encryption • Regular WEP encryption is required for wireless

  27. Standards - WiFi and WECA • Marketing and interoperability alliance for IEEE 802.11b • Founded by 3Com, Aironet, InterSil (was Harris), Lucent Technologies, Nokia and Symbol Technologies • Several others joind as member, such a Dell, Compaq, Cabletron, Apple • Compliance shown by WiFi sticker (Wireless Fidelity)

  28. Contents • Network diagrams • System elements • Standards • Spectrum usage • Technology • Key System Features

  29. U-NII Low band: 5.15-5.25 GHz Middle band: 5.25-5.35 GHz High band: 5.725-5.825 GHz ISM 902-928 MHz 2.400-2.4835 GHz 5.725-5.850 GHz U-NII Bands (5.150-5.350 & 5.725-5.825 GHz) WAVELENGTH Very Low Frequency LF MF HF VHF UHF SHF EHF INFRARED BAND DESIGNATIONS Microwaves ACTIVITIES FREQUENCY 3 cm 0.03 cm 30 cm 3 m 0.3 cm 3x105A 3,000 m 300 m 3x106m 3x105m 30 m 30,000 m 10 GHz 1 THz 1 GHz 100 MHz 100 GHz 1013Hz 100 kHz 1 MHz 100 Hz 1 kHz 10 MHz 10 kHz FM Broadcast 2.4 GHz (ISM) AM Broadcast 902 MHz (ISM) 5.8 GHz (ISM) Audible Range Spectrum Usage - Frequency bands

  30. Channel ID FCC ETSI France Japan 1 2412 2412 - 2412 2 2417 2417 - 2417 3 2422 2422 - 2422 4 2427 2427 - 2427 5 2432 2432 - 2432 6 2437 2437 - 2437 7 2442 2442 - 2442 8 2447 2447 - 2447 9 2452 2452 - 2452 10 2457 2457 2457 2457 11 2462 2462 2462 2462 12 - 2467 2467 2467 13 - 2472 2472 2472 14 - - - 2484 Spectrum Usage - 2.4 GHz channels • 2.4 GHz ISM band 2400-2483.5 MHz • Standard defines channel to be 22 MHz wide: • distance from center frequency where power has dropped 30 dB • +11MHz from center and -11MHz from center • All radios are tuned as part of manufacturing to meet this requirement: • Fit within Transmit Spectrum Mask

  31. Band Operating Channel Numbers Channel Center Frequencies U-NII lower band 5.15-5.25 GHz 36 40 44 48 5,180 MHz 5,200 MHz 5,220 MHz 5,240 MHz U-NII middle band 5.25-5.35 GHz 52 56 60 64 5,260 MHz 5,280 MHz 5,300 MHz 5,320 MHz Spectrum Usage - 5 GHz channels • Use of 5GHz ISM band is defined in three sub bands: • Lower U-NII band (5.150 - 5.270 GHz) • Middle U-NII band (5.230 - 5.350 GHz) • Upper U-NII band (5.725 - 5.825 GHz) • Current product implementations use lower and middle band only to allow operation under HiperLAN rules • 8 channels in lower and middle U-NII band • 20 MHz spacing between center frequencies of adjacent channels • Channel width: • 22 MHz @ -20dBr (first sidelobes overlap) • 40 MHz @ -28dBr (second sidelobes overlap) • 60 MHz @ -40dBr (full separation

  32. Contents • Network diagrams • System elements • Standards • Spectrum usage • Technology • Key System Features

  33. Symbol time ts “1” “0” “symbol” X = “Barker” sequence Result of multiplication Chip time tc 22 Mhz 2 Mhz Technology - DSSS • DSSS (Direct Sequence Spread Spectrum) • IEEE 2 Mbit/s (Standard) and IEEE 1 Mbit/s (Standard-Low) • QPSK/BPSK modulation • Barker sequence spreading (11 chips) • Due to the multiplication of a symbol with Barker code, the “rate-of-change” increases with a factor 11 • This means that cycle rate increases from 1 MHz to 11 MHz • In terms of spectrum this means that after RF modulation the signal is spread from 2 MHz bandwidth to 22 MHz bandwidth

  34. 5.5 MBps CCK 2 bits encoded to 4 complex code words; 2-QPSK 11 MBps CCK 8 chips 6 bits encoded to 64 complex code words; 2-QPSK 8 chips Technology - CCK • CCK (Complementary Code keying) • Accepted by IEEE 802.11 as the high speed technology (IEEE 802.11b) • Proposed by Lucent Technologies and Intersil Corporation • Bit-rates of 5.5 and 11 Mbits/sec • Uses 64 8-chips complex code sequences

  35. 5180 5220 5260 5300 5350 MHz 5150 5200 5240 5280 5320 Technology - OFDM • Orthogonal Frequency Division Multiplexing (OFDM) modulation • each “channel” composed out of 52 sub-carriers of which 48 can carry information • 64 QAM, 16 QAM, QPSK, BPSK • Data rates • 54, 48, 36, 24, 18, 12, 6 Mbit/s; auto fall back Eight channels in lower 5 GHz band 52 Carriers total ... 20 MHz One Channel (detail) Each carrier is ~300kHz wide

  36. Contents • Network diagrams • System elements • Standards • Spectrum usage • Technology • Key System Features

  37. Secret Key WEP IV IV IV PRNG Plaintext WEP TX + Secret Key PRNG Ciphertext Ciphertext + ICV'=ICV? Plaintext Integrity Alg ICV ICV Integrity Alg Key System Features - Security • Network name • In combination with closed name • MAC based Access Control • With static table or • Using RADIUS server • IEEE 802.11 defined Authentication • Open System Authentication • Shared Key Authentication • Data encryption • WEP64 • 128 RC4 • IEEE 802.1x based Security • Several Authentication methods (MD5, TLS, TTLS) • Dynamic encryption key generation

  38. Office (one room) 30 nsec Delay spread ORiNOCO radio Office 40 - 150 nsec Speed Airport 120 nsec Warehouse 130 nsec Shopping mall 90 - 200 nsec At FER <1% High (11 Mbps) 65 ns Delay spread Environment Factory 300 - 500 nsec Medium (5.5 Mbps) 225 ns IEEE Standard (2 Mbps) 400 ns IEEE Low (1 Mbps) 500 ns Key System Features - Echo robustness • Echo robustness • Ability for a receiver to differentiate between the original signal and echoes • Depends on shape of the room and objects in it • Expressed in terms of “delay spread” (average time between echo and original signal in nanoseconds) • Larger value for “delay spread” means more robust

  39. Key System Features - Interference immunity • Works in the presence of other RF emitting devices • microwave ovens • other wireless systems • via built-in acknowledge protocol • can be switched via “Interference robustness” parameter

  40. Data rate Receiver sensitivity 11 Mbps -82 dBm 5.5 Mbps -87 dBm 2 Mbps -91 dBm 1 Mbps -94 dBm Key System Features - Receiver sensitivity • Receiver sensitivity reflects quality of the radio • Receiver design • Built-in antenna • Defined as signal level at which the “radio” still is able to detect data (demodulate): • distance between stations • Noise level • Superior Receiver Sensitivity results in: • Higher degree of error free • Larger operational coverage Receiver sensitivity (at BER = 10-5)

  41. Summary • Network diagrams • System elements • Standards • Spectrum usage • Technology • Key System Features

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