Wireless LAN Technology Chapter 13 Chapter 10 (Pahlavan) Wideband local wireless networks WLAN Coverage area Data rate Batter consumption IEEE 802.11 and HIPERLAN WPAN IEEE 802.16, Bluetooth, HomeRF Data-oriented and voice-oriented MAC History of LAN Industry WANs are offered as service Cost of infrastructure Coverage area LANs are sold as “end products” You own, no service charge Analogy with PSTN/PBX LAN History-2 Emerged to enable sharing of expensive resources such as printers & to ease wiring problems Early 1980s: Three standards are developed 802.3 (Ethernet) 802.4 (Token Bus) 802.5 (Token Ring) Distinct PHY and MAC layers & topologies, but same management and bridging ~1985: Think coax Thin coax TP wiring Shorter segments, but ease of installation, lower cost, increased data rate 500 m per segment 185 m per segment Thick coax Terminator Thin coax with MAU BNC T-connector MAU MAU AUI cable 10 Mbps clients Server 10 Mbps clients Thin Coax Cheaper-net Installation Server Thick Coax Installation 100 m UTP MAU: Medium Attachment Unit 10BASE-T Repeater AUI: Attachment Unit Interface UTP: Unshielded Twisted Pair Hub-and-Spoke Architecture Server Figure 10.1: Evolution of the LANs from thick to thin cable and then to star topology using TP. Need for higher data rates Thick/Think/TP ~ 10Mbps Interconnect LANs in different buildings to share computing resources High speed multimedia applications Interconnect LANs FDDI (fiber distributed data interface): 100 Mbps in mid-1980 Mid-1990: 100 Mbps fast Ethernet (802.3) Mid-1990: 100VG-AnyLAN (802.12) Late-1990: Gigabit Ethernet (802.3) Backbone Network Router Figure 10.2: Hierarchical LANs LAN History-3 Mid 1990: ATM LAN (LANE) Emulation IEEE 802 Standards 802.3, 802.4, 802.5 are wired LANs 802.9: ISO Ethernet 802.6: MAN 802.11, 802.15, 802.16: Wireless local net 802.14 Cable modem 802.10 Security management IEEE 802.10 Security Higher Layers 802 Overview and Architecture IEEE 802.2 Logical Link Control IEEE 802.1 Management IEEE 802.1 Bridging 802.3 802.4 802.5 802.6 802.9 802.11 802.12 802.14 802.15 802.16 MAC MAC MAC MAC MAC MAC MAC MAC MAC MAC 802.3 802.4 802.5 802.6 802.9 802.11 802.12 802.14 802.15 802.16 PHY PHY PHY PHY PHY PHY PHY PHY PHY PHY Figure 10.3: IEEE 802 Standard Series WLAN Industry WLAN vs. WAN Cellular Networks Data rate (2 Mbps vs. 54 Mbps) Frequency band regulation (Licensing) Method of data delivery (Service vs. own) Early Experiences IBM Switzerland Late 1970 Factories and manufacturing floors Diffused IR technology Could not get 1 Mbps HP Labs, Palo Alto 1980 100 Kbps DSSS around 900 Mhz CSMA as MAC Experimental licensing from FCC Frequency administration was problematic, thus abandoned Motorola ~1985 1.73 GHz Abandoned after FCC difficulties What we learned Complexity and cost Bandwidth Coverage Interference Frequency administration Unlicensed Bands FCC dilemma WLAN requires ~o(10 MHz) WWAN uses 2*25 MHz tens of billions FCC solutions (mid 1980) Avoid 1-2 GHz, approve higher frequencies Motorola Altair (18-19 GHz) Release unlicensed frequency bands ISM bands (May 1985) Public vs private public use etiquette Products, Bands, Standards By late 1980s, products with diff. tech. 18-19 MHz licensed bands Spread spectrum technology in ISM bands IR 802.4L 802.11 Shoe-box sized APs (LAN extension) LAN WLAN did not materialize More bands WINForum created to obtain more license from FCC 20 MHz in PCS band 10 for voice, 10 for data Rules (based on CSMA) Listen before talk Low transmit power Restricted duration Three basic rules 1. Listen before talk (or transmit) LBT Protocol 2. Low transmitter power 3. Restricted duration of transmissions Figure 10.4 Unlicensed PCS Bands and their Spectrum Etiquette Even more bands 1992 HIPERLAN completed 23 Mbps 200 MHz, 5.15-5.35 & 17.1-17.3 GHz FCC responded by U-NII bands in 1997 OFDM based WLANs Shift in Marketing Early 1990’s expectation of LAN WLAN shift did not happen Two new directions 1: Boost the power, directional antennas Cross-building interconnect Alternative (T1) were expensive Range is fairly good (Tens of kms) 2: Reduce the size to PCMCIA card Targeted for notebooks Use SS, low power, unlicensed bands Building Cross-connect (b) PCMCIA cards and Laptops Wired Backbone (c) (a) Shoebox type LAN Extension Figure 10.5 Different forms of WLAN products (a) LAN-Extension (b) Inter-LAN Bridge (c ) PCMCIA cards for laptops Shift in Marketing Horizontal vs. vertical integration Traditionally horizontal (end products) New vertical markets (solutions) Barcode industry Financial services Health care WCANs Horizontal markets now…. New Interest from Military Mid-1990 InfoPAD BodyLAN SUO/SAS Figure 10.7: Fusion of Computers and Communications in the InfoPAD project at the University of California, Berkeley. Figure 10.8: Body LAN or Wearable LAN Figure 10.9: The urban/outskirts combat scenario for the SUO-SAS project New Interest in EU Incorporate into cellular industry ATM-based vision HIPERLAN-2 Explosion in 2000 Japan Small office sizes Laptops replacing PCs EU WLAN is seen part of the WWAN Cellular Unlicensed, high-data rate US Broadband Internet access Home networking Low-power personal networking devices To fixed network Connection Point Intelligent Office Smart Home TODAY! Win $ 1000 Ad hoc setup WLAN Position Location Figure 10.11: Wireless Networks: 2000 and Beyond Wireless Home Networking PSTN Telephone Wiring Virtual connection Internet Cable, xDSL, Voiceband modem Cable or Cable Net Satellite Figure 10.12: Today’s fragmented home access and distribution networks 12 10 Almost doubles each year 8 6 No. of Homes 4 2 0 1998 1999 2000 2001 2002 2003 2004 Figure 10.13: Growth of the home networking industry Internet Broadband Home-Access Broadband Home-Distribution or Home Area Network (HAN) Figure 10.14: Two basic technologies needed for home networking What is a HAN? Location / Navigation Phone appliances locating children and Standard phone pets Inter Comm navigating handicaps Cordless phone Home Computing Entertainment Desktop computer Audio/Visual Laptop appliances Printer Security Analog/Digital TV Scanner Systems VCR / DVD QuickCam Motion detectors Camcorder Door pins Stereo system Smart appliances System control Speakers / Headphones Oven(s) unit Fridge(s) Camera Utility metering Washing machine(s) Alarm Electricity Gas PROGRAM Fuel Water Figure 10.15: Classification of home equipment demanding networked operation Why do we need a HAN? LANs do not provide a good solution Applications diversity Number of users Bandwidth requirements Coverage area System administration Installation and maintenance HAN Technologies TP phone lines Relatively good distribution Suitable for Ethernet connection Also used for phone and xDSL Cable from cable TV Poor distribution Used for multi-channel TV signal distribution Cable-modems are required Power lines Excellent distribution Line quality is poor Frequency selective channel & impulse noise Data-rate limitations and complex DSP Wireless Ideal Bandwidth, coverage, security, interference, reliability etc. HPNA Ethernet compatible LAN over home phone lines Stand-alone adapter to connect to any device with 10Base-T interface to phone jacks Shares the medium through FDM Up converts the Manchester coding to HPNA band MAC layer is the same as 802.3 Incorporates the legacy hardware and software Network camera Home Gateway Laptop Internet Desktop telephone Multimedia PC Printer Webphone TV and Set-Up Box Camera Scanner Figure 10.17 An example of a HPNA network Figure 10.18: Phone line wirings shared among three technologies using FDM. (a) POTS uses 20 Hz – 3.4 kHz (b) xDSL uses 25 kHz – 1.1 MHz, and (c) HomePNA uses 2 MHz – 30 MHz Power Line Modems 1 Mbps type rates AM band is avoided Some use in smart appliances Interference, noise, multi-path, fading makes it a challenging medium FSK and QPSK is used for low-rates OFDM for high rates CSMA is used as MAC Figure 10.16: (a) Typical Power line transfer function (b) Typical noise level in the power lines Narrowband applications Wideband applications AM radio 3 kHz - 148.5 kHz (EU) HF band (1 - 30 MHz) frequency 9 kHz - 490 kHz (US) Figure 10.19: Frequency bands for low- and high-speed data communications over power lines. Electric Company Internet Local Transformer Meter reading communications through outside AC lines to the meter Head Control network control/security on/off, light dimmer, xDSL modem HVAC control Voice band modem Cable modem Smart appliances Sense other appliances on the power lines, breakdown alert, access through web site, email High speed computing Security systems PROGRAM Sharing Internet Sensors network connection, through power lines file transfer, share printer Figure 10.20: Power lines potential applications Home Server Security HPNA Cable, xDSL, Internet v.90 Home RF Power Line PROGRAM Figure 10.21: Evolving Home Area Networks (HAN) • Wireless • 802.16 Digital • HIPER-ACCESS Broadcast • DBS Satellite • Wired • xDSL • Cable Modem Wireless Hybrid Fiber-Coax Network PSTN Figure 10.23: Broadband home access alternatives Grandma’s Brownies HomeRF SWAP 3 cups flour 1 cup grated chocolate 1 cup sugar 1 stick butter Control Point USB Phone Cable Camera Game Pad Printer 1394 Stereo Camcorder VCR TV Multimedia (e.g. 1394) HomePNA Figure 10.22: Vision of the Home RF group at IEEE 802.15.