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IEEE 802.21: Media Independent Handover Services

IEEE 802.21: Media Independent Handover Services. Background: Wireless Internet Roaming. 現代網際網路係由許多種不同系統的通訊設備所構成，各種規格彼此之間無法互通，因而須透過其它設備來介接。在這樣的環境中如何提供有效的漫遊支援？. Scope of 802.21. Transfer c onnection. Setup n ew l ink. Search n ew l ink. Handover s ignaling Context t ransfer

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IEEE 802.21: Media Independent Handover Services

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  1. IEEE 802.21: Media Independent Handover Services

  2. Background: Wireless Internet Roaming 現代網際網路係由許多種不同系統的通訊設備所構成，各種規格彼此之間無法互通，因而須透過其它設備來介接。在這樣的環境中如何提供有效的漫遊支援？

  3. Scope of 802.21 Transfer connection Setup new link Search new link Handover signaling Context transfer Packet reception Network discovery Network selection Handover negotiation Layer 2 connectivity IP connectivity Background https://mentor.ieee.org/802.11/file/07/11-07-0453-00-0000-802-21-midweek-plenary-update.ppt Handover Initiation Handover Preparation Handover Execution IEEE 802.21 helps with handover initiation, networkselectionand interface activation

  4. Background: IEEE 802.21 • Goals • To enable handover between heterogeneous technologies • Service continuity during and after handover • IEEE 802.21 provides a framework • Allow higher level to interact with lower layers to provide session continuity without dealing with the specifics of each technology • Service continuity • Quality of service • Network discovery • Network selection assistance • Power management

  5. Link Layer Triggers State Change Predictive Network Initiated Applications (VoIP/RTP) Connection Management Handover Policy Handover Management Network Information Available Networks Neighbor Maps Network Services Mobility Management Protocols IETF 802.21 MIH Function Handover Commands Client Initiated Network Initiated Vertical Handovers Smart Triggers Handover Messages Information Service IEEE 802.21 Handover Messages Information Service L2 Triggers and Events Protocol and Device Hardware WLAN Cellular WMAN Background: IEEE 802.21 https://mentor.ieee.org/802.11/file/07/11-07-0453-00-0000-802-21-midweek-plenary-update.ppt 802.21is meant to operate across different media

  6. Outline • IEEE 802.21\ • Example Schemes • Appendix

  7. Handover 形式 • Horizontal handover • Roaming within homogeneous technologies over the same access network • Vertical handover • Roaming across heterogeneous technologies over different access networks • Hard handover (break-before-make) • Break the original connection before setting up the new one • Soft handover (make-before-break) • Make the new connection before breaking the old one

  8. IEEE 802.21 • Functionality • Reduce power consumption by avoiding unnecessary scanning and using information • 例：Turn on IEEE 802.16 module only if 802.16 is available • Reduce power consumption by using backend (core) networks • Reduce handover delay by passing security/QoS information to next point of service • Allow service providers to enforce their policies and roaming agreements

  9. IEEE 802.21 Features* • Network selection • Allows users to select between IEEE 802.3, 802.11, 802.16, 3GPP, and 3GPP2 networks • MS (mobile stations) can automatically connect to the right network by observing user selections or by user policies • MS can notify user when available networks change or a switch occurs • Session continuity • Allows make-before-break handover • Provide interface for: • Link state event reporting • Intersystem information service • Handover control (command) service

  10. Media Independent Handover (MIH) Concept

  11. General Architecture To handle/hide the particularities of each technology, 802.21 maps genericinterfaces to a set of media-dependent service access points (SAPs) (MIHF)

  12. General Architecture • MIHF user • An entity that uses the MIH SAPs to access MIHF services, and which is responsible for initiating and terminating MIH signaling • MIH_SAP • An interface allows communication between the MIHF layer and higher-layer MIHF users • MIH_LINK_SAP • An interface between the MIHF layer and the lower layers of the protocol stack • All communications between MIHF and lower layers are done through the MIH_LINK_SAP • MIH_NET_SAP • An interface supports the exchange of information between remote MIHF entities

  13. MIH Services (1/2) • Event Service • Delivers triggers on events • 例：link up, link down, new link available • Command Service • Set of standard commands for handover control • 例：switch link, configure link, initiate handover, etc • Information Service • Defines a service that provides information for faster handovers • 例：list of available networks, IP version, network operator, etc. MIH users access these services using well-defined service access points (SAPs)

  14. MIH Services (2/2) • MIH Function • An intermediate layer between upper and lower layers whose main functionis to coordinate the exchange of information and commands between different devices involved in making handover decision and executing handover • Media Independent Event Services: link up/down/going down, transmission status • Media Independent Command Services: switch links, get status • Media Independent Information Services: information elements (IEs), neighbor reports

  15. Reference Model

  16. Multiple Access Network Reference Model

  17. Reference Model: A Scenario PoA: point of attachmentPoS: point of service MN: mobile nide

  18. Reference Model: A Scenario* • Network entities • MIH point of service (MIH PoS): network-side MIHF instance that exchanges MIH messages with the MN-based MIHF. An MN may have different PoSs as it may exchange messages with more than one network entity. • MIH non-PoS: does not exchange MIH messages with the mobile node. A given network node may be a PoS for an MN with which it exchanges MIH messages and a non-PoS for a network node for which it does not. • MIH point of attachment (PoA): endpoint of a layer 2 link that includes the MN as the other endpoint • Communication reference points • R1 (MN←→Serving PoA (PoS)): used by the MN to communicate with its PoA. It may be used by the MN to gather information about the current status of its connection.

  19. Reference Model: A Scenario* • Communication reference points (續) • R2 (MN ←→ Candidate PoA (PoS)): used by the MN to communicate with a candidate PoA. It may be used to gather information about candidate PoAs before making a handover decision. • R3 (MN ←→ non-PoA (PoS)): used by the MN to communicate with an MIH PoS located on a non-PoA network entity. It may be used by a network node to inform the MN about the different IP configuration methods in the network. • R4 (PoS ←→ non-PoS): used for communications between an MIH PoS and an MIH non-PoS. It is typically used when an MIH server that is serving an MN (the PoS) needs to ask for information from another MIH server (the non-PoS). • R5 (PoS ←→ PoS): used between two different MIH PoSs located at different network entities

  20. Event Service • Event Service • Events related to handover can be originated at the MAC or MIHF layer located in the node or at the point of attachment to the network • Local (terminal side) and remote (network side) events • Events may trigger user actions

  21. Event Service • Event Service (續) • Provides event classification, event filtering and event reporting corresponding to dynamic changes in link characteristics, links status, and link quality • Events: administrative, state change, link parameter, predictive, link synchronous, and link transmission

  22. Event Service Event flow model for link events and MIH events

  23. Event Service: L2 Triggers (Link Events) Disconnected Connected • State Change Events • Link Up • Link Down • Link Parameters Change • Predictive Events • Link Going Down • Network Initiated Events • Load Balancing • Operator Preferences Link Going Down Link Down Link Up WLAN Make before Break Link Switch Link Up WWAN Time Triggers minimize connectivity disruption during link switching

  24. Event Service: Link Events 說明

  25. Event Service: MIH Events 說明

  26. Command Service • Command Service • Enables MIH users to manage and control link behavior relevant to handovers and mobility • Commands flow from user to MIH and then to link layer • Commands allow users to switch links • User communicates separately with each technology(commands donot flow fromone technologyto another)

  27. Command Service • Command serviceflow

  28. Information Service • Information Service • Provides information about networks in a particular geographical area • Information delivery via queries or by broadcast/multicast • Generally static information • 802.21 defines what information is required • Does not define how the service is accessed 802.21 Information Server 802.16 802.11 802.3

  29. Information Service • Information Service (續) • Provides the capability for obtaining necessary information for handovers including neighbor maps, link layer information, and availability of services • Access neighbor maps for networks in a geographic area from any network entity • Wi-Fi hotspot knows about cellular towers and vice versa • Static link layer informational parameters • QoS support and restricted networks. • Use reports to allow efficiency • Channel range prevents the need for scanning. • Vendor specific features: Prioritize networks, network labels

  30. Example Message Flow Mobile-initiated handover from 3Gto WLAN

  31. MIH Protocol Frame Format

  32. Information Elements • Information elements • Contain general Information (operators), access network (roaming, cost, security, QoS), PoA (location, data rate, channel range), higher layer, other information (vendor specified) • Information elements are delivered as a Type-Length-Value (TLV) messages

  33. Network Initiated Handover • Network initiated handover • MIH Handover Initiate: Suggested PoA • MIH Handover Prepare: Current to target network • MIH Handover Commit: Client commits to do handover • MIH Handover complete: New network to old network. Send all buffered packets

  34. MAC Layers 802.16-AN 802.11-AN MIHFUE 802.11-AN MIHFNW(IS) MME Network Initiated Network Selection (Example)* UE Network Operator UE Discovery and Registration MIH-Register-Event.Req() MIH-Register-Event.Resp() DL-Burst* Link-Detect Link-Event.Detect(link_info) MIH-Info.Req MIH-Info.Resp Unfavorable Network Beacon Beacon Link-Detect Link-Event.Detect(link_info) MIH-Info.Req MIH-Info.Resp Favorable Network => Selection www.ietf.org/proceedings/05nov/slides/mipshop-6/mipshop-6.ppt

  35. MIHFUE Mobile IP HA New-FA 802.11-AN MME 802.11 MAC Network Controlled Handover (Example)* Operator Network UE 802.11 Network Network Selection Legend Mobile-IP Signaling MIH-Remote-Link-Switch.Req(802.11 nwk) MIH signaling over new link L3-switch.Ind Proxy Rtr Solicitation Proxy Rtr Advertisement Link-Associate L2-Procedures (Security, Re-association, QoS Neg.) Link-Event-Up(802.11 nwk) MIH-Link-Event-Up FBU Mobile IP update procedure over new link Release MIH-Remote-Link-Switch.Resp www.ietf.org/proceedings/05nov/slides/mipshop-6/mipshop-6.ppt

  36. MIHF Protocol • The MIHF protocol allows peer MIHF entities to interact with each other • MIH communication may imply use of unacknowledged connection-less transport services to reduce transport overhead and ensure efficiency and reduced latency in the delivery of MIH messages

  37. MIHF Protocol* • MIHF protocol • Container for MIH messages for 802.11 defined in IEEE 802.11u • Container for MIH messages for 802.16 defined in IEEE 802.16g • Transport for MIH protocol is defined in the IETF MIPSHOP working group • IEEE 802.21 transport • CS, ES, IS messages are transported over L2 or L3 • 802.11u is defining transport of 802.21 messages over 802.11 • MIPSHOP is defining transport over IP

  38. MIHF Protocol: Usage Models* www.ietf.org/proceedings/05nov/slides/mipshop-6/mipshop-6.ppt • Direct model • Proxy model Remote ES/CS MIHFUE MIHFMME Remote ES/CS Remote ES/CS MIHFUE MIHFproxu MIHF

  39. 802.21 Amendments for MIH* • 802.21 amendments for MIH • MIH Capability indication in beacon • MAC Layer Management Entity (MLME) Service Access Point (SAP): Link up indication, Scan confirm • Information service for generic network selection: IS query frame • Transport of MIHF protocol over 802.11

  40. Summary • 802.21 is a standard protocol for handover initiation, network selection, handover • 802.21 provides a common interface to L3 and higher mobility protocols • Has triggers that allow higher layers to take action • Has commands that allow higher layer to request actions • Has information service that allows all layers to not have to discover the static information

  41. Remarks • Similar technologies • Unlicensed Mobile Access (UMA) technology is basically a mobile-centric version of 802.21 • UMA is regarded to provide roaming and handover between GSM, UMTS, Bluetooth and 802.11 networks • http://www.umatoday.com/ • Since June 19 2005, UMA is a part of the ETSI 3GPP standardization process under the GAN (Generic Access Network) Group

  42. Remarks • Similar technologies • WiOptiMo technology enables any application running on a device to use the best Internet connection among all the wired/wireless access providers available, guaranteeing persistence in case of weak or no signal and managing the switch among them (when needed/convenient) in a transparent way, without interrupting the active application/session. • http://hal.inria.fr/inria-00001015/en/or "WiSwitch: Seamless Handover between Multi-Provider Networks“.

  43. Outline • IEEE 802.21 • Example Schemes • F. Cacace and L. Vollero, “Managing Mobility and Adaptation in Upcoming 802.21-Enabled Devices”, Proc. 4th Int'l Wksp. Wireless Mobile Applications and Services on WLAN Hotspots, pp. 1–10, Sep. 2006\ • A. Dutta, S. Das, D. Famolari, Y. Ohba,K. Taniuchi, V. Fajardo, R. M. Lopez, T. Kodama, and H. Schulzrinne, “Seamless Proactive Handover Across Heterogeneous Access Networks”, Wireless Personal Communications, 43(3): 837–855, November 2007 • Appendix

  44. Abstract* • One emerging characteristic of electronic devices is the increasing number of connectivity interfaces (aka NICs) towards the outside world. That obviously translates in a set of technical issues related to their management in order to provide seamless connectivity when the connections move from one interface to another. The IEEE 802.21 is a recent effort of IEEE that aims at providing a general interface for the management of NICs. In this paper we discuss how the upcoming standard may be effectively exploited in a mobile context in order to hide network heterogeneity to end users. To accomplish this task, we propose a centralized element called Mobility Manager interfacing with the 802.21 sublayer and responsible for the application of connectivity policies. Based on a real testbed, we showed that the new standard and the MM can be used to improve network performance experienced by the end user. Moreover we showed how the MM can interact with adaptive applications in order to improve further the range of usability of real-time applications.

  45. IEEE 802.21 Architecture • Three primary services • Media Independent Event Service (MIES) • Media Independent Command Service (MICS) • Media Independent Information Service (MIIS)

  46. Media Independent Event Service* • Support for both local and remote events notification to the upper layers of a MS • Common events provided through MIHF • Link up • Link down • Link parameters change • Link going down • L2 handover imminent

  47. Media Independent Command Service* • Used to gather information about the status of connected links and to execute mobility and connectivity decisions • Commands can be both local, if issued by an upper layer entity, or remote, if sent by an entity of the access network • Typical commands • “MIH poll” and “MIH configure” to poll connected links asking for their status and to configure new links, respectively

  48. Media Independent Information Service* • Provide information to mobile nodes about available networks and services • Use standard and platform independent description language to represent that information: static and dynamic. • Static: names and the providers of mobile terminal’s neighboring network • Dynamic: channel, security and the MAC addresses. • Advantages • Help significantly in the definition of high level handoverdecisions and policies. • Avoids any specific and access-dependent discovery method for the automatic detection of neighbor networks

  49. Media Independent Information Service • Example of stack elements interaction under IEEE 802.21

  50. Applications Mobility Manager Mobility Manager 802.21 MIH Function • Mobility Manager • A centralized system entity running onboard mobile devices and directly interfacing services provided by 802.21 compliant network interfaces • To deliver higher level services to applications in order to enable active content adaptation, e.g. adaptation coordinated with underlying network services

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