20 -Mobility20 Mobility6: Wireless and Mobile Networks 6-1802.15: personal area network less than 10 m diameterrepl cement f r c bles radius ofSPPreplacement for cables (mouse, keyboard, headphones)Mradius ofcoverageSSPP ad hoc: no infrastructure master/slaves:l ii P slaves request permission to send (to master) master grants requestsMSMaster deviceSlave deviceParked device (inactive)P 802.15: evolved from Bluetooth specification24-25 GHz radio band6: Wireless and Mobile Networks 6-2Parked device (inactive)P2.4-2.5 GHz radio band up to 721 kbpsComponents of cellular network architecture connects cells to wide area net manages call setup (more later!)MSC handles mobility (more later!) covers geographical regioncellPublic telephonenetwork andMobile Switching Centerregionbase station(BS) analogous to 802.11 APmobile usersattach t nt k th h BSMobile Switching network, andInternetto network through BSair-interface:physical and link layer protocol between Centerpmobile and BSwired network5: DataLink Layer 5-3Cellular networks: the first hopCellular networks the f rst hopTwo techniques for sharing biltBS di mobile-to-BS radio spectrumcombined FDMA/TDMA:combined FDMA/TDMAdivide spectrum in frequency channels, divide each channel into time time slotseach channel into time slots CDMA: code division frequencybandsmultiple access5: DataLink Layer 5-4Cellular standards: brief surveyCellular standards br ef survey2G systems:voice channels2G systems:voice channels IS-136 TDMA: combined FDMA/TDMA (north america) GSM (global system for mobile communications): combined FDMA/TDMA most widely deployedmost widely deployed IS-95 CDMA: code division multiple accessGSMDon’t drown in a bowlof alphabet soup: use thisff l5: DataLink Layer 5-5for reference onlyCellular standards: brief surveyCellular standards br ef survey2.5 G systems:voice and data channels2.5 G systems:voice and data channels for those who can’t wait for 3G service: 2G extensionsgeneral packet radio service(GPRS)gp() evolved from GSM  data sent on multiple channels (if available)enhanced data rates for global evolution (EDGE)enhanced data rates for global evolution (EDGE) also evolved from GSM, using enhanced modulation  Date rates up to 384K CDMA-2000 (phase 1) data rates up to 144Kevolved from IS955: DataLink Layer 5-6evolved from IS-95Cellular standards: brief surveyCellular standards br ef survey3G systems:voice/data3G systems:voice/data Universal Mobile Telecommunications Service (UMTS) GSM next step, but using CDMApg CDMA-2000….. more (and more interesting) cellular topics due to mobility (stay tuned for details)5: DataLink Layer 5-7mob l ty (stay tuned for deta ls)What is mobility?What s moblty? spectrum of mobility, from thenetworkperspective:pfy,fppno mobilityhigh mobilityyhgh mobltymobile wireless user, using same access pointmobile user, passing through multiple access points while mobile user, connecting/ disconnecting pointaccess points while maintaining ongoing connections (like cell phone)disconnecting from network using DHCP. 5: DataLink Layer 5-8phone)Mobility: VocabularyMob l ty Vocabularyhome network:permanent “home” of mobilehome agent: entity that will perform mobility functions on f(e.g., 128.119.40/24)perform mobility functions on behalf of mobile, when mobile is remotewide area Permanent address:address in home wide area networknetwork, can alwaysbe used to reach mobilee.g., 128.119.40.186correspondent5: DataLink Layer 5-9Mobility: more vocabularyMob l ty more vocabularyvisited network:network in which mobile currently Permanent address:remains Care-of-address:address yresides (e.g., 79.129.13/24)Permanent address:remains constant (e.g., 128.119.40.186)Careofaddressaddress in visited network.(e.g., 79.129.13.2) wide area networkf i n nt: ntit foreign agent: entity in visited network that performs mobility functions on correspondent: wants 5: DataLink Layer 5-10mobility functions on behalf of mobile. correspondent: wants to communicate with mobileHow do youcontact a mobile friend:yI wonder where Consider friend frequently changing  search all phone won r wh r Alice moved to?Consider friend frequently changing addresses, how do you find her?pbooks? call her parents? h l  expect her to let you know where he/she is?5: DataLink Layer 5-11Mobility: approachesMob l ty approachesLet routing handle it: routers advertise permanent gpaddress of mobile-nodes-in-residence via usual routing table exchange.routing tables indicate where each mobile locatedrouting tables indicate where each mobile located no changes to end-systemsLet end-systems handle it: Let endsystems handle it: indirect routing:communication from correspondent to mobile goes through home h f dd agent, then forwarded to remotedirect routing:correspondent gets foreign address of mobile sends directly to mobile5: DataLink Layer 5-12address of mobile, sends directly to mobileMobility: approachesMob l ty approachesLet routing handle it: routers advertise permanent gpaddress of mobile-nodes-in-residence via usual routing table exchange.routing tables indicate where each mobile locatednot scalableto millions ofrouting tables indicate where each mobile located no changes to end-systemslet end-systems handle it: mobileslet endsystems handle it: indirect routing:communication from correspondent to mobile goes through home h f dd agent, then forwarded to remotedirect routing:correspondent gets foreign address of mobile sends directly to mobile5: DataLink Layer 5-13address of mobile, sends directly to mobileMobility: registrationyghome networkvisited networkid 12wide area networkmobile contacts foreign agent on 2forei n a ent contacts home foreign agent on entering visited networkforeign agent contacts home agent : “this mobile is resident in my network”End result: Foreign agent knows about mobile5: DataLink Layer 5-14gg Home agent knows location of mobileMobility via Indirect Routingygforeign agent receives packets, visitednetworkhome agent intercepts packets, forwards to foreign agentp,forwards to mobilewide area homenetwork3wide area network241correspondent paddresses packets using home address of mobilemobile replies directly to correspondent5: DataLink Layer 5-15pIndirect Routing: commentsgmm Mobile uses two addresses:mt ddss:s d