Transcript General Considerations for Media Independent Handover

• IEEE 802.21 MEDIA INDEPENDENT HANDOVER
• DCN: 21-04-00xx-00-0000
• Title: General Considerations for Media Independent
Handover (MIHO)
• Date Submitted: July 8, 2004
• Presented at IEEE 802.21 session #03 in Portland, Oregon
• Authors or Source(s): Yogesh Bhatt, Alistair Buttar, James Han,
Floyd Simpson, Nat Natarajan, Les Eastwood
• Abstract: Definition of 'Service Types' would provide a good
basis for subsequent specification of Layer 2 Hints and Triggers.
The growing interest in Handover between different terminals
will necessitate efficient collaboration with several other
standards bodies on a 'roadmap' on an on-going basis.
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General Considerations for Media
Independent Handover (MIHO)
Yogesh Bhatt, Alistair Buttar, Simpson Floyd,
James Han, Nat Natarajan, Les Eastwood
Motorola
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Contents
• Current Handover Landscape
• Where can IEEE802.21 make an impact ?
• Conclusions
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Current Handover Landscape
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Heterogeneous Access System
Example 1: Loosely Coupled
Operator’s
IP Network
Access System X
Internet
Firewall
Proxy AAA
Access System Y
(operator owned)
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Access System Y
(Third party)
Heterogeneous Access System
Example 2: Tightly Coupled
RAN of an
Access
System X
Access
System X
Core
Operator’s IP Network
Firewall
Access system Y Network
IWU
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Internet
Loose and Tight Coupling
• Loose Coupling
• Access systems as peer IP access network
• Maintain distinct systems for bearer traffic
• Reuse AAA services for peer access system
• Tight Coupling
• Hierarchical relationship between access systems
•
•
Access system lower in hierarchy provides alternate access to network
Traffic from alternate access can be routed through parent’s core network
• Various implementations possible between 'loose' and 'tight'
• Number of wireless air interfaces is increasing continually
• Products are already appearing on the market so market value
of 802.21 MIHO standard would be maximized by early
results, ie. roadmap of deliverables
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Related Standards
• 802.1 Network Management & Security, 802.11 WLAN, 802.16
BWA , 802.20 MBWA, …
• IETF - SEAMOBY, TRIGTRANS, …
• 3GPP - cellular, with WLAN interworking work item
• 3GPP2 - cellular, with WLAN interworking work item
• ETSI - NGG (Next Generation Networks Globalization)
• ITU-T NGN (Next Generation Networks) Focus Group
• TIA (Telecommunication Industry Association)
• TMF (Tele Management Forum)
• …..
• Close collaboration necessary to promote synergy
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Examples - Imperatives for Timely 802.21
• Future 3GPP to WLAN Interworking work will
include
•
•
•
Scenario 4: Service Continuity
The goal of this scenario is to allow the services supported in Scenario 3 to
survive a change of access between WLAN and 3GPP systems, ie. basic
mobility. The change of access may be noticeable to the user, but there will
be no need for the user/UE to re-establish the service
Scenario 5: Seamless Services
The goal of this scenario is to provide seamless service continuity, as
defined in between the access technologies, for the services supported in
Scenario 3. One example is the handover of a voice call between the cellular
network and the VoIP over WLAN, whereby the interruption of service is
masked from the user, and security features are maintained.
802.21 'Services' will be critical to support the 3GPP roadmap,
especially Scenarios 4 & 5
• Fast MIP handover
• Impossible without Layer 2 triggers
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Where can IEEE802.21 make an
Impact ?
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MIHO considerations (1)
• Link “Availability” or “new network” discovery
• All the media sensed by a Device and link quality estimate
for each
• loading and network congestion
• Link Triggers may be used for that
• Network provider selection
• Needs Network availability information
• User preferred operator
• Operator preferred, defaults, capabilities
• How to convey this information ?
• Link layer connection and configuration
• Triggers would help with link identifiers and layer 2 ID to
layer 3 ID translation tables
• Trigger information packet format (not content) must be
standardized
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MIHO considerations (2)
• Controlling the access to Network
• No compromise on security
• Latency considerations for cross domain AAA.
• QoS mapping between different links when HO
• shall be possible to map and adapt QoS classes according to
individual access technology
• Support low power procedures
• Battery efficient network scanning (e.g. enhanced 802.11
passive scanning vs. active scanning)
• Optimize network scanning opportunities to coincide with
scheduled awake times (e.g. minimize switching between
active and deep sleep states)
• Minimize protocol overhead as much as possible to reduce
active duty cycle (e.g. for network neighborhood)
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MIHO considerations (3)
• Mobile IP shall not be assumed as the only Mobility protocol.
• Handover latency targets can be set based on application types
• Categorized apps in broader classes like hard Real-time loss tolerant, soft
real time loss sensitive, lossless assured delivery and loss tolerant non
real time
• For each of these category factor a range of delay and packet loss
contributed by HO in end-to-end value.
• Flexible handover decision making support
• Terminal-initiated network assisted
– Only the device can see all the available networks
– Only the Device have knowledge of all applications running
presently
•
Hence, can make better HO decisions with some help from network.
• Terminal-initiated should be considered in the first phase of standardization
to align with likely early market approach.
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Network Selection Recommendations
• 802.21 Group should support network selection control by both
mobile node and infrastructure, which also means:
• Selection entity and measurement entity may be different
• Network selection not only by bandwidth and roaming
agreements but on feature capabilities such as
• Fast MIP or not,
• Supported services (SMS, SIP,…)
• Network selection algorithm can be vendor specific, but
enable the network selection protocol and procedures
• capability advertising, request/ responses of information,
messages and their format (possible borrowing from IETF)
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Security Concerns
• Trigger information must be trustable
• If sent over the current link, authenticated with current trust
mechanism
• If sent over new links, authentication may be needed
• Network selection information must be trustable
• Signal strength either measured directly by the selection
entity (less security issues) or
• If sent from measurement entity to selection entity,
authentication is required (possibly certificates)
• Capability information may be confidential, may need
protection
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Conclusions
• Use phased standardization approach
• L2 triggers to support multi-mode terminals in short term
• Need to liaise closely with other standards bodies
• Develop full 'Layer 2.5' approach as longer term goal
• Add 'Services' section to requirements document to support a
wide variety of handover scenarios based on needs of
• Users, operators, multi-mode terminals, heterogeneous
networks
• Preserve freedom to choose handover algorithms based on User,
Operator and Vendor interests.
• Optimize network layer performance based on physical (usually
RF) and link conditions
• Arrive at a clear conclusion of the initial stage work that can
help focus subsequent technical specification work
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