ECE544: Communication Networks-II, Spring 2007Today’s LectureMobility in Cellular NetworksCellular Concept of MobilityFunctional ElementsGSM RegistrationMobile Data NetworksMobile Networks: IP ApproachMobile Networks: ATM ApproachMobile Networks : “+M” Protocol StacksMobile IP Refer to: http://computer.org/internet/ v2n1/perkins.htM http://www.ietf.org/html. charters/mobileip-charter.html http://wwwtgs.ctit.utwente.nl/Docs/ education/advanced/mobile/Tutorials/MobileIPv6.pdf Slides on Mobile IP at: http://ing.ctit.utwente.nl/WU4/Documents/47Name, Address, RoutingMobility Problem: The Internet ViewpointConstraintsIP’s subnet model vs. MobilityBasic Mobile IPKey componentsRoute OptimizationTerminologySlide 20Binding Cache Creation/UpdateForeign Agent Smooth HandoffMobile ATM DetailsMobile ATM: System ModelMobile ATM: Location MgmtMobile ATM: HandoffMobile ATM: Use with CellularMobile ATM: Use with 3G/WLANToday’s HomeworkECE544: Communication Networks-II, Spring 2007D. RaychaudhuriLecture 8Includes tutorial materials from C. Perkins & D. ReiningerToday’s Lecture•Mobility in networks•Mobile IP•Mobile ATM, 3GMobility in Cellular NetworksCellular Concept of Mobility•Users have a home system but can register at visited systems to make and receive calls – Single Number Service•Users can roam among systems during a call and the call is handed-off without being dropped.Functional ElementsHome System Visited SystemHLR ACVLRAuthenticationCenter – Authenticates usersVisitor Location Register-Maintains temporary information onVisiting users.Home Location Register –Maintains current customerLocation and service profileGSM RegistrationHLR/ACVLROld VLRVisited System2) VLR queriesprevious VLR for user’s(actually the user’s smartcard) permanent ID.Handset1) Visited system detects handset,handset transmits temporary ID assignedby previous system.3) The VLR sendsa registration messageto the HLR.Mobile Data NetworksMobile Networks: IP Approach•Mobile IP based on the notion that today’s Internet protocols will evolve to provide most voice/data services:Connectionless protocols offer lower complexity implementationDistributed mobility management (no MSC!)Needs further enhancements for flow QoS supportIP ROUTER+ Mobility ExtIP TERMINALIP ACCESS POINTRadioAir Interface IP/RSVP + “M” IP HOST/SERVERStandard IPIP Pkts w/ DLC segmentsIP packetsRadio Microcell 1Radio Microcell 2Mobile Networks: ATM Approach•Mobile ATM a candidate architecture for telco scenarios where an ATM access network is available:Support for service integration & flow QoSConnection-oriented framework suitable for dynamic handoffMay be used for micro-level mobility, with mobile IP for macro-levelATM SWITCH+ Mobility ExtMobile TERMINALATM ACCESS POINTRadioAir InterfaceMobile ATM“M” UNI/NNIHOST/SERVERIPOAATM cellsRadio Microcell 1Radio Microcell 2MAC PDU’sIP services+ voiceApplication DataMedium Access ControlRadio Transport Convergence LayerRadio Physical Medium Dependent LayerWirelessControlRadioPHYRadioAccess LayersUserPlaneControlPlaneSignaling, etc.+ mobility ext..VC# 1 2nATM Network LayerSIG VCRadiolinkcontrolMultiplexed user dataRadio SignalData Link Control (or “LLC”)ATM Adaptation LayersMobile Networks : “+M” Protocol StacksApplication DataMedium Access ControlRadio Transport Convergence LayerRadio Physical Medium Dependent LayerWirelessControlRadioPHYRSVP +Mob Ext..Flow # 1nIP Network Layer (incl.. Mob IP)RadiolinkcontrolMultiplexed user dataRadio SignalData Link Control (or “LLC”)TCP/UDP/RTPControlFlowWireless ATM Protocol StackWireless IP Protocol StackOptionalMobile IPRefer to:http://computer.org/internet/v2n1/perkins.htMhttp://www.ietf.org/html.charters/mobileip-charter.htmlhttp://wwwtgs.ctit.utwente.nl/Docs/education/advanced/mobile/Tutorials/MobileIPv6.pdfSlides on Mobile IP at: http://ing.ctit.utwente.nl/WU4/Documents/47Name, Address, Routing•Name: is a location independent identifier of a host•Address: indicates where a given host is located.•Route: tells how to get to a destinationMobility Problem: The Internet Viewpoint•Internet addresses are assigned in a topologically significant manner.–A mobile host must be assigned a new address when it moves.•Change host address  connection breaks.•Retain host address  routing fails.•Host address must be preserved regardless of its location.Constraints•Inter-operability with TCP/IP protocol suite.•Existing networking apps should run unmodified on mobile hosts.•System should provide Internet-wide mobility.•No modification on existing routing infrastructure should be required.•Solution should be independent of wireless hardware technology.•Solution should have good scaling properties.IP’s subnet model vs. Mobility•Terminals move from one IP subnet to another, but have the wrong “subnet prefix” for the destination subnet.•Solution: two-tier IP addressing–The mobile keeps its static IP address, but borrows the service of a “care-of-address” on whatever IP subnet it happens to be visiting.–A “care-of-address”, offered by a mobility agent, can be shared by visiting mobiles.Basic Mobile IP •How does it work?–Agent discovery: advertisement/solicitation–MH registration–Use of Care-of-Address (COA)–Proxy ARP (Address Resolution Protocol)–Packet tunneling–Triangle routingKey componentsHNR1 R3FN FNR2HAMHMHCHFAMobile Host:a host or router capableof changing its point ofattachment to the InternetForeign Network:a network, other than MA’s homenetwork, that MH is currently attachedto.Corresponding Host:a host or router communicationgwith a mobile node.Home Network:the network identifiedwith a mobile nodeHome Address:MH’s permanent IP address,network ID of this address identifiesthe mobile’s home network.Home Agent:a router attached to the MH’s home networkmaintains current location information for the MHis responsible for forwarding packets destined for theMH when MH is away from home.Foreign Agent (FA)a router in the foreign network that the MH is visitingprovides routing services to the MH while registredde-tunnels datagram to MHmay serve as default router for outgoing packet from MHRoute OptimizationRoute Optimization•Provides a means for nodes to–cache the bindings of a mobile node–tunnel their own datagrams directly to the care-of-address–bypass mobile node’s home agent during datagram delivery•Allow datagrams sent based on