Vertical Handovers in Heterogeneous Next-Generation Wireless Networks

1. Vertical Handovers in Heterogeneous Next-Generation Wireless Networks Prof. George Kormentzas, University of the Aegean

2. Presentation Outline • Mobility in the heterogeneous next-generation networking environment • The handover process • Mobility management protocols from IETF

3. The Heterogeneous Next-Generation Wireless Environment • Diverse access networks, with coverage at different ranges and capacity at different levels, interconnected through a common IP-based core Applications Broadcast 5G IP-based Core 3G WiMAX LTE WiFi

4. Today's Perspective Virtual Mobile Operator BSS+OSS Functions Billing, Provisioning, etc... Virtual MobileOperator Subscriber Mobile Operator BSS+OSS Functions Billing, Provisioning, AAA, etc... Mobile Operator Subscriber

5. Today's Perspective Virtual Mobile Operator Use Cases: - New Subscription - Making a Call - Billing BSS+OSS Functions Billing, Provisioning, etc... Virtual MobileOperator Subscriber Mobile Operator BSS+OSS Functions Billing, Provisioning, AAA, etc...

6. Today's Perspective Virtual Mobile Operator Use Cases: - New Subscription - Making a Call - Billing BSS+OSS Functions Billing, Provisioning, etc... Virtual Operator Subscriber Mobile Operator BSS+OSS Functions Billing, Provisioning, AAA, etc...

7. Today's Perspective Virtual Mobile Operator Use Cases: - New Subscription - Making a Call - Billing BSS+OSS Functions Billing, Provisioning, etc... Virtual Operator Subscriber Mobile Operator BSS+OSS Functions Billing, Provisioning, AAA, etc...

8. Tomorrow's Perspective‏ Virtual Mobile Operator BSS+OSS Functions Billing, Provisioning, AAA, etc... Virtual Operator Subscriber WiMax Operator1 WiMax Operator2 Cable Operator1 Local Operator Subscriber Cable Operator2 Mobile Operator1 Mobile Operator2 HotSpot Owner1 HotSpot Owner2 HotSpot Owner...

9. Technical Issues • Mobile IP Roaming (transparent to the subscriber) • Inter-Domain Handover (HO) • Mobile Node (MN) Network Preferences Steering • Inter-Domain Billing (on a large scale number of peer domains)

10. Business Issues • Introduction (acceptance) of new components such as Global Auction Market • Addition of new features in already existing components such as Clearing Houses • Use of operators signalling infrastructure • Real-Time billing

11. Mobility Management in Heterogeneous Networks • Mobility is a key issue in future heterogeneous environments • Mobility management is comprised of 2 components: • Location management (facility to find where a Mobile Node is located so as to initiate service) • Handover management (facility to allow a Mobile Node to keep its connection active when changing point of attachment to the network) • Today, mobility is supported in several cellular and wireless technologies.

12. Handover Types • With respect to the technology • Intra-technology (Horizontal) • Inter-technology (Vertical) • With respect to administrative domain • Intra-domain • Inter-domain • With respect to whether resources are allocated in advance in target network • Backward (resources are reserved) • Forward (resources are not reserved) • With respect to the entity that initiates the handover • Network-initiated • Mobile-initiated

13. Vertical Handover Use cases • Coping with imminent network unavailability • Mainly due to movement causing degradation of the signal strength • Also due to maintenance work scheduled by the network operator • Opting for extra or better service • Better in this case can be: cheaper, more secure, enhanced, etc. • Optimizing radio resource usage • Mainly driven by the operator for better utilization of the resources

14. Benefits • For operators • Increased system capacity and better load management • Provision of better services to subscribers in areas where the coverage of one of the networks is not good or demand for services high • Revenues from roaming agreements with other operators • For users • Always best connected • Best connection according to QoS, cost, user preferences, power consumption, etc.

15. Reference Scenarios • Scenario 1: Coping with imminent network unavailability • Use Case 1: Leaving the Office (Wi-Fi to WiMAX) • Use Case 2: Emergency Medical Support (Wi-Fi to UMTS to WiMAX) • Scenario 2: Opting for extra and better services • Use Case 3: Arriving at the airport (UMTS to Wi-Fi) • Use Case 4: Mobile TV on a Train (DVB to Wi-Fi) • Scenario 3: Optimizing Radio Resources Usage • Use Case 5: Improving service Experience (WiMAX to UMTS) • Use Case 6: Releasing resources for other Services (WiMAX to DVB)

16. Reference Scenarios Reference Scenario 1 flow chart • Scenario 1: Coping with imminent network unavailability • Use Case 1: Leaving the Office (Wi-Fi to WiMAX)

17. Reference Scenarios Reference Scenario 2 flow chart • Scenario 2: Opting for Extra and Better Services • Use Case 4: Mobile TV on a Train (DVB to Wi-Fi)

18. Reference Scenarios Reference Scenario 3 flow chart • Scenario 3: Optimizing Radio Resources Usage • Use Case 5: Improving Service Experience (WiMAX to UMTS)

19. Services • Voice over IP • Video Tele Conferencing • Audio Streaming • Video Streaming • Interactive Games • HTTP Services • Email Download

20. The Handover Process (1/2) • Handovers occur when a mobile node changes its Layer-2 network Point of Attachment (PoA) • i.e., the end-point of a L2 link between the mobile node and the network (e.g., WLAN Access Point) • This L2 handover may subsequently trigger reconfiguration of the mobile node’s IP address used as location identifier (L3 handover)

21. The Handover Process (2/2) • 3 phases: Initiation, Preparation & Execution

22. Phases of the Handover Process (1/3) • Handover Initiation • Compilation of information about • Application QoS requirements • User preferences • Operator policies (shaped according to regulatory constraints) • Available networks • Establishment of firm decisions on • Need for the handover • Target network

23. Phases of the Handover Process (2/3) • Handover Preparation • Actions that can be taken in advance to mitigate the impact of handover execution • Resource allocation to the target network • L2 authentication and association • Movement detection • IP parameters configuration for the target network • Preparations for data forwarding from previous to target network

24. Phases of the Handover Process (3/3) • Handover Execution • Connection to target network • Location update • Forwarding of data until location update is completed • Release of resources in previous network

25. HO Evaluation Performance metrics • HO delay • Packet loss • Out of sequence packets • Signaling overhead • Power consumption • Call drop probability • Probability of false HO

26. Who makes Standards for Handovers • Handovers within the same technology are addressed by the corresponding Standard Development Organizations • 3GPP, 3GPP2, IEEE, DVB • Handovers between heterogeneous technologies are addressed mainly by the IETF • The interoperability required to realize the B3G vision calls for coordinated actions and integrated solutions to mitigate the effects of handovers (delays and packet losses) • Today we see joint efforts from 3GPP, IETF, DVB, IEEE

27. Network-layer Mobility Management Protocols from IETF • Terminal-based • Terminals are involved in handover signaling • Need for special software in terminals • Examples: Mobile IP (MIP), Hierarchical MIP, Fast MIP • Network-based • A relatively new concept in IETF • Mobility support is provided by the network • Example: Proxy MIP

28. Data from CN to MN Data from MN to CN Overview of Mobile IPv4 CN HomeAddr. HA HN ANG Data from CN to MN Data from MN to CN Signaling Anchor Point for both local & global mobility FA FA FA CoA PoA PoA PoA AN PoA

29. MIP - Remarks • MIP provides the basis for terminal mobility management • It does not differentiate between global and local mobility • Enhancements to basic MIPv4 functionality allow for direct communication between Correspondent Node (CN) and Mobile Node (route optimization) • In this case, however, the CN must be mobility-aware • In MIPv6 • Foreign Agents (FAs) are not needed (there is no problem with limited addresses) • Route optimization is supported as a standard feature • MIP introduces significant delay due to procedures like • Movement detection • New Care-of Address (CoA) configuration • Location update

30. MN Overview of Hierarchical MIPv6 CN GMAP HN ANG Data from CN to MN Data from MN to CN Signaling LMAP Anchor Point for global mobility Regional CoA FHR FHR FHR PoA Anchor Point for local mobility PoA PoA PoA On-link CoA2 AN On-link CoA1

31. Hierarchical MIPv6 - Remarks • Extension to MIPv6 that allows for local mobility handling • Limits the amount of Mobile IPv6 signaling outside the local domain (signaling between the Mobile Node, its Correspondent Nodes, and its Home Agent) • Offers location privacy • Location tracking of a mobile node by its corresponding nodes or its home agent is difficult because they only know its Regional CoA and not its on-Link CoA • The local Mobility Anchor Point (MAP) can be located at any level in a hierarchical network of routers, including the Access Network Gateway (ANG)

32. Overview of Fast MIPv6 CN GMAP HN ANG Data between MN and CN Signaling Anchor Point for global mobility FHR PAR NAR PoA PoA PoA PoA AN MN New link detected MN

33. Fast MIPv6 - Remarks • It enables a Mobile Node (MN) to quickly detect that it has moved to a new subnet by providing the new access point and the associated subnet prefix information when the MN is still connected to its current subnet • Aims at minimizing service interruption during handovers by reducing handover latency and allowing for packet buffering at network nodes • It allows for transfer of context between network nodes • It allows for network-initiated handovers • The Previous Access Router (PAR) sends an unsolicited router advertisement message (with information about neighboring links) • Requires cooperation between network nodes • Next Access Router (NAR) and PAR must have a trust relationship • Difficult to be deployed in practice beyond administrative domains

34. Overview of Proxy MIPv6 CN GMAP HN ANG Data between MN and CN Signaling LMA MAG New MN detected Anchor Point for global mobility MAG Anchor Point for local mobility PoA PoA PoA Basic IPv6 Signaling AN MN MN

35. Proxy MIPv6 - Remarks • Doesn’t need Mobile IPv6 functionality in the IPv6 stack of the mobile node • The proxy mobility agent in the network (MAG) performs the signaling and does the mobility management on behalf of the node • The functionality is only supported inside the Proxy MIP domain. Outside that the MN needs to be mobility-capable • The MN keeps the same address inside the Network-based Localized Mobility Management (NETLMM) domain for remote communication with the CN. This results in enhanced location privacy. • Minimizes signaling overhead in the wireless parts of the network

36. Trends in Network-layer Mobility Management Protocols • Differentiate between global and local mobility • Handle mobility in hierarchical manner • Add functionality at the network side to support closer-to-seamless mobility • Add support for transfer of context (information regarding access control, QoS profile, header compression for real-time applications, etc.) between serving and target networks • Provide mobility support for unmodified terminals (network-based mobility management) • Improve privacy

37. Latencies of Network-layer Handover Solutions • Made up of latencies introduced by link and network layers • At application level these latencies are cumulative • Link-layer latencies are due to • Late detection of link state changes • Lengthy scanning and authentication/association procedures • Network-layer latencies are due to • Late detection of the loss of IP connectivity • Lengthy IP layer parameter configuration process (e.g., address, default router, DNS, etc.) • Time-consuming address registration updates • Conclusion • Despite of any optimizations in the network-layer procedures, seamless handovers cannot be experienced unless • Link-layer handover procedures are also optimized • Smooth cooperation between link and network-layer functions is established

38. IEEE 802.21 standard - Approach • Facilitates handover initiation and preparation for vertical handovers between 3GPP, and IEEE 802.3, 802.11, 802.16 networks • Introduces a common interface to L2. It provides 3 services • The Media Independent Event service • Events and triggers corresponding to dynamic changes in link characteristics, status and quality • The Media Independent Command service • Commands for the MIH users to control handover relevant link states • The Media Independent Information service • Mostly static network information within a geographical area that can be used towards efficient handover decisions (dynamic information is obtained directly from access networks)

39. IEEE 802.21 - Services Media Independent SAP Media Dependent SAP

40. IEEE 802.21 MIH Event Service

41. IEEE 802.21 MIH Command Service

42. IEEE 802.21 MIH Information Service • General Information • E.g., Network type, Operator ID, Service Provider ID, Country Code • Access Network Specific Information • E.g., Network ID, Roaming Partners, Cost, Network QoS, Network nominal data rate, Channel range, IP configuration methods, Network capabilities, Type of mobility management protocol supported • PoA Specific Information • E.g., MAC address, Geographical location, Channel range • PoA Specific Higher Layer Service Information • E.g., Supported Subnets, IP address • Other • Vendor specific services

43. Summary • Mobility in heterogeneous networks is important for both operators and end-users. • Mobility management in such environment is a complicated process • Several proposals exist for mobility management at the network layer in heterogeneous networks (MIP and enhancements) • Exploitation of link-layer intelligence and exchange of information between mobile node and network is deemed important • A handover framework built around IEEE 802.21 is promising towards the delivery of closer-to-seamless experience • There are open research issues regarding, for example, the interfacing of MIHF to other protocols, the support of DVB, the transportation of the MIHF messages and the positioning of the functionality in the evolved 3GPP network architecture