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Maximilian Riegel
ICM Networks, Advanced Standardization
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Prolog: The ubiquitous WLAN n Today’s road worriers require access to the Internet everywhere. n WLAN is more than just cable replacement, it provides hassle-free broadband Internet access everywhere. Office Hospital Office Congress hall, Hotel Semi-public Railway WLAN Corporate Station Plant WLAN Remote Airport Public Access WLAN Home WLAN Campus n Coverage in ‘hot-spots’ sufficient. n IEEE802.11b meets the expectations for easiness, cost and bandwidth. WLAN-IEEE802.11 Tutorial (Maximil
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Prolog: WLAN has taken off ... n Lots of serious WLAN activities have been started – All big players have products (Cisco, Intel, …) – Integrated WLAN solutions appearing (Apple, IBM, ...) n The prediction have been exceeded by actual market. For comparison: Total PC world market in ‘01: ~ 120 Mio pcs.; > 30 % portable. 25 :/$1UILI>PLR@ 20 Source: Frost&Sullivan (2000-03) 15 10 5 0 ’98 ’99 ’00 ’01 ’02 n Ruling technology is IEEE802.11b (Wi-Fi) [11Mb/s, 2.4 GHz]. WLAN-IEEE802.11 Tutorial (Ma
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Outline n Part 1: Wireless Internet System Architecture n Part 2: IEEE802.11 Overview n Part 3: Physical Layer n Part 4: Medium Access Control n Part 5: MAC Layer Management n Part 6: WLAN Mobility n Part 7: WLAN Security n Part 8: Public Hotspot Operations n Part 9: WLAN – UMTS Interworking WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 4 © Siemens, 2002
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Part 1: Wireless Internet system architecture n Generic Internet network architecture n Layering means encapsulation n IEEE802.11 – seamless integration into the Internet n IP based network architecture n Wireless LAN IEEE802.11 basic architecture n What is unique about wireless? WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 5 © Siemens, 2002
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Generic Internet network architecture 3ROLF\6HUYHU $$$6HUYHU :/$1$FFHVV Peer Peer (Client) (Web-Server) Internet/Web Applications www www http http tcp tcp ip ip ip ip ip ip ip ip 802.2 802.2 802.2 802.2 link link link link link link 802.3 802.3 phy phy phy phy phy phy WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 6 © Siemens, 2002
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Layering means encapsulation HTML user data http appl. header tcp tcp header application data TCP segment ip ip header IP datagramm 802.2 Ethernet ip header tcp header appl. header user data 14 bytes 20 bytes 20 bytes Ethernet frame 64 - 1500 bytes WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 7 © Siemens, 2002
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IEEE802.11 - seamless integration into the Internet KWPO [PO [VO VPLO www W3C +773 )73 6073 08$ 1)6 '16 6103 7&3 6&73 8'3 ,3 333 $53 HQFDS ,QWHUQHW IETF ITU ,6'1 $70 6'+ *60 ETSI ATMF WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 8 © Siemens, 2002
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)/$*6 IP based network architecture 193.175.26.92 131.34.3.35 www www http http N-DATA.indication N-DATA.request N-DATA N-DATA N-DATA tcp tcp ip ip ip ip ip ip ip ip link link link link link link link link phy phy phy phy phy phy phy phy 1234 Version Length Type of Service Total Length ip = connectionless, TOS (pre-diffserv) Identification Fragment offset D T R 0 0 non-reliable, Time-to-live Protocol Header checksum Source IP Address (32bit) end-to-end, D: Delay Destination IP Address (32 bit) T
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Wireless LAN IEEE802.11 basic architecture local distribution network internet Netscape apache http http tcp tcp ip ip ip ip ip 802.2 ppp 802.2 802.2 802.2 802.2 ppp Bluetooth 802.3 802.3 802.3 Bluetooth 802.3 IEEE802.11 Client Access Point Access Router Server WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 10 © Siemens, 2002
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What is unique about wireless? n Difficult media – interference and noise – quality varies over space and time – shared with “unwanted” 802.11 devices – shared with non-802 devices (unlicensed spectrum, microwave ovens) n Full connectivity cannot be assumed – “hidden node” problem n Mobility – variation in link reliability – battery usage: requires power management – want “seamless” connections n Security – no physical boundaries – overlapping LANs n Multiple international regulatory requirement
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Part 2: IEEE802.11 Overview n Wireless IEEE802.11 Standard n IEEE802.11 Configurations n IEEE802.11 Architecture Overview n IEEE802.11 Protocol Architecture n Wireless LAN Standardization WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 12 © Siemens, 2002
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Wireless IEEE802.11 Standard n Operation in the 2.4GHz ISM band – North America: FCC part 15.247-15.249 – Europe: ETS 300 - 328 – Japan: RCR - STD-33A n Supports three PHY layer types: DSSS, FHSS, Infrared n MAC layer common to all 3 PHY layers n Robust against interference n Provides reliable, efficient wireless data networking n Supports peer-to-peer and infrastructure configurations n High data rate extension IEEE802.11b with 11 Mbps using existing MAC layer Approved June 1997 802.11b ap
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IEEE802.11 Configurations n Independent – one “Basic Service Set”, BSS Station – “Ad Hoc” network AH2 – direct communication Station Ad Hoc Network AH3 – limited coverage area Station AH1 n Infrastructure Server – Access Points and stations – Distribution System interconnects DISTRIBUTION SYSTEM Multiple Cells via Access Points to form a single Network. AP AP A B • extends wireless coverage area BSS-B Station A1 Station B2 Station Station BSS-A A2 B1 WLAN-IEEE802.11 Tutorial (Maximilian Riegel)
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IEEE802.11 Architecture Overview n One common MAC supporting multiple PHYs n Two configurations – “Independent” (ad hoc) and “Infrastructure” n CSMA/CA (collision avoidance) with optional “point coordination” n Connectionless Service – Transfer data on a shared medium without reservation – data comes in bursts – user waits for response, so transmit at highest speed possible – is the same service as used by Internet n Isochronous Service – reserve the medium for a single connection and provide a
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IEEE802.11 Protocol Architecture n Station Management – interacts with both MAC Management and PHY Management n MAC Layer Management Entity LLC = 802.2 – power management MAC Layer MAC – handover Management Sublayer MAC – MAC MIB n MAC Entity – basic access mechanism PHY Layer PLCP Sublayer Station Management – fragmentation Management PHY PMD Sublayer – encryption n PHY Layer Management – channel tuning – PHY MIB n Physical Layer Convergence Protocol (PLCP) – PHY-specific, supports common PH
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Wireless LAN Standardization WIG Wireless Interworking Group IEEE 802.11 ETSI BRAN 802.11f: Inter Access Point Protocol 8076,QWHJUDWLRQ 802.11e: 4R6(QKDQFHPHQWV 802.11i:6HFXULW\(QKDQFHPHQWV HiperLAN/2 0$& IEEE 802.11 802.11h DFS & TPC DFS & TPC 802.11a 802.11g 802.11b 3+< 5 GHz 5 GHz 2,4 GHz 2,4 GHz 2,4 GHz 54 Mbit/s 54Mbit/s 54Mbit/s 11Mbit/s 2 Mbit/s Current standardization topics WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt Page 17 © Siemens, 2002
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Part 3: Physical layer n IEEE802.11 2.4 GHz & 5 GHz Physical Layers n Frequency Hopping Spread Spectrum n Direct Sequence Spread Spectrum n DSSS Transmit Spectrum and Channels n IEEE802.11a 5GHz PHY Layer n IEEE802.11g: Further Speed Extension for the 2.4 GHz Band n Spectrum Designation in the 5GHz range n IEEE802.11h: Spectrum and Transmit Power Management n ... when will 5 GHz WLANs come? n PHY Terminology n Physical Layer Convergence Protocol (PLCP) WLAN-IEEE802.11 Tutorial (Maximilian Riegel
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Power Frequency Power Power IEEE802.11 2.4 GHz & 5 GHz Physical Layers n Baseband IR, 1 and 2Mbps, 16-PPM and 4-PPM n 2.4 GHz Frequency Hopping Spread Spectrum – 2/4 FSK with 1/2 Mbps – 79 non overlapping frequencies Time of 1 MHz width (US) n 2.4 GHz Direct Sequence Spread Spectrum – DBPSK/DQPSK with 1/2 Mbps spreading – Spreading with 11 Bit barker Code – 11/13 channels in the 2.4 GHz band Frequency Frequency n 2.4 GHz High Rate DSSS Ext. (802.11b) – CCK/DQPSK with 5.5/11 Mbps n 5 GHz OFD
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Frequency Hopping Spread Spectrum f5 f4 f3 FREQUENCY f2 f1 1 2 3 4 5 678 9 10 11 12 TIME n 2.4GHz band is 83.5MHz wide (US & Europe) n Band is divided into at least 75 channels n Each channel is < 1MHz wide n Transmitters and receivers hop in unison among channels in a pseudo random manner n Power must be filtered to -20db at band edge , © Siemens, 2002 AMPLITUDE
