Wireless mesh network - WikiLeaks mesh network...12/31/2015 Wireless mesh network ... An important possible application for wireless mesh networks is VoIP. ... (Hybrid Wireless Mesh

  • View
    216

  • Download
    4

Embed Size (px)

Text of Wireless mesh network - WikiLeaks mesh network...12/31/2015 Wireless mesh network ... An important...

  • 12/31/2015 Wireless mesh network - Wikipedia, the free encyclopedia

    https://en.wikipedia.org/wiki/Wireless_mesh_network 1/6

    Diagramshowingapossibleconfigurationforawirelessmeshnetwork,connectedupstreamviaaVSATlink(clicktoenlarge)

    WirelessmeshnetworkFromWikipedia,thefreeencyclopedia

    Awirelessmeshnetwork(WMN)isacommunicationsnetworkmadeupofradionodesorganizedinameshtopology.Itisalsoaformofwirelessadhocnetwork.Wirelessmeshnetworksoftenconsistofmeshclients,meshroutersandgateways.Themeshclientsareoftenlaptops,cellphonesandotherwirelessdeviceswhilethemeshroutersforwardtraffictoandfromthegatewayswhichmay,butneednot,connecttotheInternet.Thecoverageareaoftheradionodesworkingasasinglenetworkissometimescalledameshcloud.Accesstothismeshcloudisdependentontheradionodesworkinginharmonywitheachothertocreatearadionetwork.Ameshnetworkisreliableandoffersredundancy.Whenonenodecannolongeroperate,therestofthenodescanstillcommunicatewitheachother,directlyorthroughoneormoreintermediatenodes.Wirelessmeshnetworkscanselfformandselfheal.Wirelessmeshnetworkscanbeimplementedwithvariouswirelesstechnologyincluding802.11,802.15,802.16,cellulartechnologiesorcombinationsofmorethanonetype.

    Contents

    1 History

    1.1 Architecture

    1.2 Management

    1.3 Applications

    1.4 Operation

    1.5 Multiradiomesh

    1.6 Researchtopics

    2 Protocols

    2.1 Routingprotocols

    2.2 Autoconfigurationprotocols

    3 CommunitiesandProviders

    https://en.wikipedia.org/wiki/File:Wireless_mesh_network_diagram.jpghttps://en.wikipedia.org/wiki/Telecommunications_networkhttps://en.wikipedia.org/wiki/Radiohttps://en.wikipedia.org/wiki/Node_(networking)https://en.wikipedia.org/wiki/Mesh_networkinghttps://en.wikipedia.org/wiki/Network_topologyhttps://en.wikipedia.org/wiki/Wireless_ad_hoc_networkhttps://en.wikipedia.org/wiki/Mesh_nodehttps://en.wikipedia.org/wiki/802.11shttps://en.wikipedia.org/wiki/802.15https://en.wikipedia.org/wiki/802.16

  • 12/31/2015 Wireless mesh network - Wikipedia, the free encyclopedia

    https://en.wikipedia.org/wiki/Wireless_mesh_network 2/6

    3 CommunitiesandProviders

    4 Seealso

    5 References

    6 Externallinks

    History

    Architecture

    Wirelessmesharchitectureisafirststeptowardsprovidingcosteffectiveanddynamichighbandwidthnetworksoveraspecificcoveragearea.Wirelessmeshinfrastructureis,ineffect,anetworkofroutersminusthecablingbetweennodes.It'sbuiltofpeerradiodevicesthatdon'thavetobecabledtoawiredportliketraditionalWLANaccesspoints(AP)do.Meshinfrastructurecarriesdataoverlargedistancesbysplittingthedistanceintoaseriesofshorthops.Intermediatenodesnotonlyboostthesignal,butcooperativelypassdatafrompointAtopointBbymakingforwardingdecisionsbasedontheirknowledgeofthenetwork,i.e.performrouting.Suchanarchitecturemay,withcarefuldesign,providehighbandwidth,spectralefficiency,andeconomicadvantageoverthecoveragearea.

    Wirelessmeshnetworkshavearelativelystabletopologyexceptfortheoccasionalfailureofnodesoradditionofnewnodes.Thepathoftraffic,beingaggregatedfromalargenumberofendusers,changesinfrequently.Practicallyallthetrafficinaninfrastructuremeshnetworkiseitherforwardedtoorfromagateway,whileinadhocnetworksorclientmeshnetworksthetrafficflowsbetweenarbitrarypairsofnodes.[1]

    Management

    Thistypeofinfrastructurecanbedecentralized(withnocentralserver)orcentrallymanaged(withacentralserver),[2]botharerelativelyinexpensive,andveryreliableandresilient,aseachnodeneedsonlytransmitasfarasthenextnode.Nodesactasrouterstotransmitdatafromnearbynodestopeersthataretoofarawaytoreachinasinglehop,resultinginanetworkthatcanspanlargerdistances.Thetopologyofameshnetworkisalsoreliable,aseachnodeisconnectedtoseveralothernodes.Ifonenodedropsoutofthenetwork,duetohardwarefailureoranyotherreason,itsneighborscanquicklyfindanotherrouteusingaroutingprotocol.

    Applications

    Meshnetworksmayinvolveeitherfixedormobiledevices.Thesolutionsareasdiverseascommunicationneeds,forexampleindifficultenvironmentssuchasemergencysituations,tunnels,oilrigs,battlefieldsurveillance,highspeedmobilevideoapplicationsonboardpublictransportorrealtimeracingcartelemetry.AnimportantpossibleapplicationforwirelessmeshnetworksisVoIP.ByusingaQualityofServicescheme,thewirelessmeshmaysupportlocaltelephonecallstoberoutedthroughthemesh.

    Somecurrentapplications:

    https://en.wikipedia.org/wiki/Node_(networking)https://en.wikipedia.org/wiki/Router_(computing)https://en.wikipedia.org/wiki/Peer-to-peer

  • 12/31/2015 Wireless mesh network - Wikipedia, the free encyclopedia

    https://en.wikipedia.org/wiki/Wireless_mesh_network 3/6

    U.S.militaryforcesarenowusingwirelessmeshnetworkingtoconnecttheircomputers,mainlyruggedizedlaptops,infieldoperations.Electricmetersnowbeingdeployedonresidencestransfertheirreadingsfromonetoanotherandeventuallytothecentralofficeforbillingwithouttheneedforhumanmeterreadersortheneedtoconnectthemeterswithcables.[3]ThelaptopsintheOneLaptopperChildprogramusewirelessmeshnetworkingtoenablestudentstoexchangefilesandgetontheInterneteventhoughtheylackwiredorcellphoneorotherphysicalconnectionsintheirarea.The66satelliteIridiumconstellationoperatesasameshnetwork,withwirelesslinksbetweenadjacentsatellites.Callsbetweentwosatellitephonesareroutedthroughthemesh,fromonesatellitetoanotheracrosstheconstellation,withouthavingtogothroughanearthstation.Thismakesforasmallertraveldistanceforthesignal,reducinglatency,andalsoallowsfortheconstellationtooperatewithfarfewerearthstationsthanwouldberequiredfor66traditionalcommunicationssatellites.

    Operation

    TheprincipleissimilartothewaypacketstravelaroundthewiredInternetdatawillhopfromonedevicetoanotheruntilitreachesitsdestination.Dynamicroutingalgorithmsimplementedineachdeviceallowthistohappen.Toimplementsuchdynamicroutingprotocols,eachdeviceneedstocommunicateroutinginformationtootherdevicesinthenetwork.Eachdevicethendetermineswhattodowiththedataitreceiveseitherpassitontothenextdeviceorkeepit,dependingontheprotocol.Theroutingalgorithmusedshouldattempttoalwaysensurethatthedatatakesthemostappropriate(fastest)routetoitsdestination.

    Multiradiomesh

    Multiradiomeshreferstoauniquepairofdedicatedradiosoneachendofthelink.ThismeansthereisauniquefrequencyusedforeachwirelesshopandthusadedicatedCSMAcollisiondomain.Thisisatruemeshlinkwhereyoucanachievemaximumperformancewithoutbandwidthdegradationinthemeshandwithoutaddinglatency.ThusvoiceandvideoapplicationsworkjustastheywouldonawiredEthernetnetwork.Intrue802.11networks,thereisnoconceptofamesh.ThereareonlyAccessPoints(AP's)andStations.Amultiradiowirelessmeshnodewilldedicateoneoftheradiostoactasastation,andconnecttoaneighbornodeAPradio.

    Researchtopics

    OneofthemoreoftencitedpapersonWirelessMeshNetworksidentifiedthefollowingareasasopenresearchproblemsin2005

    NewmodulationschemeInordertoachievehighertransmissionrate,newwidebandtransmissionschemesotherthanOFDMandUWBareneeded.

    AdvancedantennaprocessingAdvancedantennaprocessingincludingdirectional,smartandmultipleantennatechnologiesisfurtherinvestigated,sincetheircomplexityandcostarestilltoohighforwidecommercialization.

    FlexiblespectrummanagementTremendouseffortsonresearchoffrequencyagiletechniquesarebeingperformedforincreasedefficiency.

    https://en.wikipedia.org/wiki/Mesh_networkinghttps://en.wikipedia.org/wiki/One_Laptop_per_Childhttps://en.wikipedia.org/wiki/Iridium_satellite_constellationhttps://en.wikipedia.org/wiki/Earth_stationhttps://en.wikipedia.org/wiki/Packet_(information_technology)https://en.wikipedia.org/wiki/Internethttps://en.wikipedia.org/wiki/Routinghttps://en.wikipedia.org/wiki/Algorithmhttps://en.wikipedia.org/wiki/Carrier_sense_multiple_accesshttps://en.wikipedia.org/wiki/Collision_domainhttps://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexinghttps://en.wikipedia.org/wiki/Ultra-widebandhttps://en.wikipedia.org/wiki/Directional_antennahttps://en.wikipedia.org/wiki/Smart_antennahttps://en.wikipedia.org/wiki/Multiple_antenna_researchhttps://en.wikipedia.org/wiki/Spectrum_management

  • 12/31/2015 Wireless mesh network - Wikipedia, the free encyclopedia

    https://en.wikipedia.org/wiki/Wireless_mesh_network 4/6

    WikimediaCommonshasmediarelatedtoMeshnetwork.

    CrosslayeroptimizationCrosslayerresearchisapopularcurrentresearchtopicwhereinformationissharedbetweendifferentcommunicationslayersinordertoincreasetheknowledgeandcurrentstateofthenetwork.Thiscouldenablenewandmoreefficientprotocolstobedeveloped.Ajointprotocolwhichcombinesvariousdesignproblemslikerouting,scheduling,channelassignmentetc.canachievehigherperformancesinceitisproventhattheseproblemsarestronglycorelated.[4]Itisimportanttonotethatcarelesscrosslayerdesigncouldleadtocodewhichisdifficulttomaintainandextend.[5]

    Protocols

    Routingprotocols

    Therearemorethan70competingschemesforroutingpacketsacrossmeshnetworks.Someoftheseinclude:

    AODV(AdhocOnDemandDistanceVector)B.A.T.M.A.N.(BetterApproachToMobileAdhocNetworking)Babel(protocol)(adistancevectorroutingprotocolforIPv6andIPv4withfastconvergenceproperties)DNVR(DynamicNIxVectorRouting)DSDV(DestinationSequencedDistanceVectorRouting)DSR(DynamicSourceRouting)HSLS(HazySightedLinkState)HWMP(HybridWirelessMeshProtocol)IWMP(InfrastructureWirelessMeshProtocol)forInfrastructureMeshNetworksbyGRECOUFPBBrazilMRP(Wirelessmeshnetworksroutingprotocol)byJangeunJunandMihailL.SichitiuOLSR(OptimizedLinkStateRoutingprotocol)OORP(OrderOneRoutingProtocol)(OrderOneNetworksRoutingProtocol)OSPF(OpenShortestPathFirstRouting)RoutingProtocolforLowPowerandLossyNetworks(IETFROLLRPLprotocol,RFC6550)PWRP(PredictiveWirelessRoutingProtocol)TORA(TemporallyOrderedRoutingAlgorithm)ZRP(ZoneRoutingProtocol)

    TheIEEEisdevelopingasetofstandardsunderthetitle802.11stodefineanarchitectureandprotocolforESSMeshNetworking.

    AlessthoroughlistcanbefoundatAdhocroutingprotocollist.

    Autoconfigurationprotocols

    Standardautoc