Report of Mobile Computing.docx
- 文档编号:27866579
- 上传时间:2023-07-05
- 格式:DOCX
- 页数:10
- 大小:47.86KB
Report of Mobile Computing.docx
《Report of Mobile Computing.docx》由会员分享,可在线阅读,更多相关《Report of Mobile Computing.docx(10页珍藏版)》请在冰豆网上搜索。
ReportofMobileComputing
Mobileandubiquitouscomputing
WeiLuo
ReportforEnglishpracticalskills
Vasa28.2.2012
Contents
1Introduction.......................................................................1
2Mobileandubiquitouscomputing...................................1
3Background........................................................................2
4Challengesandsolutions..................................................4
5Conclusion..........................................................................6
6Reference............................................................................8
1Introduction
Mobileandubiquitouscomputingisanemergingtechnologyintechnologyfieldinrecentyears.Itcouldn’timagedinpreviousyearswhencomputingonlyexistindesktopandserver-racks.TherearemanyfactorscontributingtoboomofMobileandUbiquitouscomputing.Firstly,Moore,co-founderofIntel,oncesaidthat“Thenumberoftransistorsonachiproughlydoubleseverytwoyears.Anditspricewilldrophalf”.Hisviewhasbeenconfirmedbyhistory.Nowadays,thebulkofdevicesarebecomingmoreandmorelight.Asdevicesbecomesmaller,wecaneasilycarriedittoeverywhere.Ontheotherhand,thankstothecheapprice,wecandeploylargescalesofthesedevicestoembedintomanypartsofoureverydayphysicalworld.Secondly,nowadays,wirelessconnectivitybecomesmoreprevalentthanbefore;wecanmoreeasilyconnectourdevicewithconventionalcomputerandServerbyBluetoothorWIFI.Thisabilityprovidesusanovelmeanstodealwithdataandextremelyfacilitatesthisindustrydeveloping.
2MobileandUbiquitousComputing
2.1Mobileandhand-heldcomputing
Severalyearsago,peopleusedtorelatecomputingwithcumbersomedesktopsorserver-rack.However,thingsarechanging.Mobilecomputingaroseasaparadigminwhichuserscouldcarrytheirpersonaldeviceandretainsomeconnectivitytoothermachines.Inabout1980,itbecamepossibletobuildmachinesthatwerelightenoughtocarryandcouldbeconnectedtoeachotherviatelephoneline.Technologyevolutionhasledtomoreorlessthesameideabutfarbetterfunctionalityandperformance:
thepresent-daycounterpartisthelaptop,netbookandsmartphone,eachwithseveralformsofwirelessconnectivityincludingcellularnetworks,WIFIandBluetooth.
Thenewtrendsoftechnologicalevolutionleadtohandheldcomputing,suchassmartphone,tabletandothers.ThankstotherevolutioncausedbyStevenJobs,handledevicemadeabigdifferencecomparedtoonestwoorthreeyearsage.Thereasoncouldbeconsideredfromtwoperspectives.
Fromthehardwarepointofview,manufacturersaddmoreandmorebuilt-insensorsinthesmartphones,includingGPS,proximitysensorsandothers.Thesesensorsgivethedevicetheabilitytodetectenvironment.Ontheotherhand,theseparametersthatsensorsdetectedwillcontributetosoftwaredeveloperscreatingmoreamazingapps.
Fromthesoftwareperspective,mobileoperatingsystems,suchasAndroid,IOSandWindowsphone7,provideamiddlewarefordeveloper.Thesemakedevelopinganddebuggingmoreeasilythanbefore.
However,newchallengesemergeinthisfield.Industryexperthavetoconsidethowtoprovidecontinuousconnectivityformobiledevicesthatpassinandoutoftherangeofbasestation.Thesecondproblemishowtoenablecollectionofmobiledevicewhenthereisnoinfrastructure.
2.2Ubiquitouscomputing
ThistermwasfirstlyprovidedbyMarkWeiserin1988.Ubiquitousisasynonymof“pervasivecomputing”.Weiserbelievestheincreasingprevalenceofcomputingdevicesisleadingtorevolutionaryshiftsinthewaywewouldusecomputers.Althoughitsoundsprettystraightforward,thatchangewillhaveadramaticeffectonthewayweusecomputerscomparedtothemainframeerabeforeit.Weiser’sideaof‘oneperson,manycomputersisnotequivalenttothecommonsituationinwhichweeachhaveseveralcomputersthataremoreorlessalike-oneatwork,oneathome,alaptopandperhapsasmartphonewecarryinthehand.Rather,inubiquitouscomputing,computersmultiplyinformandfunction,notjustinnumber,tosuitdifferenttasks.
Forexample,supposethatalltheinertdisplayandwritingsurfacesinaroom,suchaswhiteboards,books,piecesofpaper,Post-itnotesandsoonwerereplacedbytensorhundredsofcomputersandtouchscreens.Booksalreadyhaveelectronicformwhichextremelyincreasestheirutility.Notonlycanyouviewthemindevice,butalsosearchtext,lookupthemeaningofwordsandsearchrelatedideasviaInternet.
3Background
3.1Volatilesystems
Thesetofusers,softwareandhardwareinmobileandubiquitoussystemishighlydynamicandchangeunpredictably.Therelevantformsofvolatilesystemsinclude:
●failureofdevicesandcommunicationlink
●changesinthecharacteristicofcommunicationsuchasbandwidth
●thecreationanddestructionofassociations-logicalcommunicationrelationships-betweensoftwareonthedevices
However,Volatilityisnotadefiningpropertyofmobileandubiquitoussystems.Thereisanothersystemthatencompassesthischaracteristic,likepeer-to-peercomputing.
3.2Smartspace
Physicalspaceisthefoundationofmobileandubiquitouscomputing.Mobilityhappensbetweenphysicalspaces;Ubiquitouscomputingisembeddedintophysicalspaces.Sowecallthisspaceassmartspace,whichisanyphysicalspacewithembeddedwithservices-thatis,servicesprovidedonlyorprincipallywithinthatphysicalspace.
3.3Devicemodel
Thecharacteristicsofadeviceusedinmobileandubiquitouscomputingislistedinfollowing:
●Limitedenergy
Inordertoportableorembeddedintoenvironment,thesedevicefetchenergybybatteryratherplugin.Andthesmallerandlighterthedeviceneedstobe,theloweritsbatterycapacitywillbe.Itismoreorlessinconvenienttoreplaceorrechargethedevicefromtheviewoftimeandphysicalaccess.Computingandaccesstomemoryandotherformsofstorageallconsumepreciousenergy.Wirelesscommunicationisparticularlyenergy-intensive.Soifwewantadevicelastaslongaspossibleonagivenlevelofbatterysupply,algorithmneedtobesensitivetotheenergythattheyconsume.Butultimately,theprobabilityofdevicefailureisincreasingduetobatterydischarge
●Resourceconstraints
Comparedtoconventionaldesktopsorserver-racks,thedevicesofmobileandubiquitouscomputinghavelimitedcomputationalresourcesintermsofprocessspeed,storagecapacityandnetworkingbandwidth.Thisisadilemmasinceenergyconsumptionwilldramaticallyboomasweimprovethosecharacteristics.Ontheotherhand,tomakedevicesmoreportableortoembedthemintotheenvironmententailsmakingthemphysicallysmall.Givenlimitationsimposedbymanufacturingprocessesrestrictedthetransitedinthenode
.
●Sensorsandactuators
Toenabletheirintegrationwiththephysicalworld,thedevicesmustbecontext-awarebymeansofsensorsandactuators.Sensorsmeasurethephysicalparametersandsupplythesevaluestothesoftware.Inturn,softwarehandlesthesedataretrievefromsensorstoconductrelevantactuatorsmovement.Awidevarietyofeachcomponentexists.Onthesensorside,forexample,therearesensorsthatmeasureposition(GPS),orientation(compasssensor),light(opticalsensor)andothers.Actuatorsincludeprogrammableair-conditioningcontrollerandmotors.Animportantissueaboutsensorsisaccuracy,whichwillleadtospuriousbehavior,suchasaninappropriateresponsetowhatturnedouttobethewronglocation.ButInaccuracyisonecharacteristicofsensors,whichcan’tbeeliminated.
Thedevicesdescribedabovemaysoundsomewhatexotic.However,notonlyaretheycommerciallyavailable,buttheyareevenmass-produced.Herearetwoexamplesofthat
Motes:
Figure1.Mote
Inthefieldofenvironmentalsensing,Motesareprevalentlyused.Theyaredesignedtobeembeddedintotheenvironmentandcapabletowitlesslydiscoveroneanotherandtransfersensedvalueamongstthemselves.(Zerfos2010:
34)
Smartphone:
Figure2.Smartphone
Smartphonesarequitedifferentexamplesofadeviceinthesystemswearediscussing.Theirprincipalfunctionsarecommunicationandimaging.But,withthehelpofmobilesystemssuchasAndroid,IOSandWindowsphone,theyareprogrammableforquiteawidevarietyofapplications.
4.Challengesandsolution
4.1Association
Asmentionedbefore,theconnectionbetweenmobileandubiquitousdevicesisnotalwayssteady.
Sothedevicemaydisappearunexpectedly.Ontheotherhand,wehopedeviceshavecapabilitytointeroperatepreferablywithoutuserintervention.Inotherwords,itmeansdevicesappearinginthesmartspaceneedtobeabletobootstrapthemselvesontothelocalnetworktoenablecommunicationwithotherdevicesandassociateappropriatelyinthesmartspace.
4.1.1Networkbootstrapping
Typically,communicationstakeplaceoveralocalnetwork,whichispreconditionisthatdevicesmustfirstacquireanaddressonthelocalnetwork
Nowadays,Expertsalreadyhavewell-establishedsolutionstotheproblemofintegratingadeviceintoanetwork.Somesolutionsrelyonserversaccessiblewithinthesmartspace,suchasDHCPservers.(George2011:
842)
Amoreinterestingcaseisassigningnetworkparametersintheabsenceofanyservices.Thisisdesirablebothtosimplifythesmartspaceandtoavoidexcessivedependenciesonserversthatmightfail.TheIPV6standardincludesaprotocolallowingserverlessaddressassignment
4.1.2Theassociationproblemandboundaryprinciple
Whendeviceswanttocommunicatewithotherdevicesinasmartspace,theyfaceanassociatio
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- Report of Mobile Computing