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IEEE 802.21 MEDIA INDEPENDENT HANDOVER

DCN: 21-07-0351-00-0000

Title: Inter-Tech Handover Activity

Date Submitted: September, 2007

Presented at IEEE 802.21 session #22 Big Island

Authors or Source(s):

  Vivek Gupta

Abstract: Update on Handover activities across SDOs and messages/directions for 802.21

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IEEE 802.21 presentation release statementsThis document has been prepared to assist the IEEE 802.21 Working

Group. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.

The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.21.

The contributor is familiar with IEEE patent policy, as outlined in Section 6.3 of the IEEE-SA Standards Board Operations Manual <http://standards.ieee.org/guides/opman/sect6.html#6.3> and in Understanding Patent Issues During IEEE Standards Development http://standards.ieee.org/board/pat/guide.html> 

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802.21 How we Started ?

Optimize L3 Handovers– Network Discovery & Selection (ND&S)

– Enable Network initiated Handovers

– Lower Power Operation

Assumptions: – Dual Radio Operation

– Make before break as primary mode of operation

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802.21 - Industry Observations ND&S a big issue only for 802.11 networks

– Not such a big issue for other networks operating primarily in licensed bands

– Inter-RAT Neighbor Advertisements are good enough– Operators skeptical about dedicated IS server

L3 MM Protocols are not widely deployed– CMIP not that widely used– PMIP may not require significant 802.21 services

Network initiated HO are compelling– Require significant investments– Done in network specific manner

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Handovers – Key Issues Co-existence & Interference issues prevent dual

radio operation in many UEs

Need optimized HO solutions for Single Radio operation (one radio transmitting at a time ONLY…)– May not be able to do Make operation before Break– Need to transition to 3GPP from WiMAX during voice call

Key 802 involved Handover Scenarios– WiMAX <> 3GPP2/3GPP– WiMAX <> WiFi

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Key Elements of Handover Functionality

Capability Motivation Complexity

Inter-RAT network advertisements

Helps reduce power consumption on the device. Required for single radio operation. The WiMAX module will only turn on if WiMAX coverage is available

Low

Inter-RAT Traffic Anchoring

Eliminates L3 mobility signaling in inter-RAT mobility by keeping L3 anchor in the previous RAT access gateway. Requires inter-RAT interface between access gateways

Low-Medium

Inter-RAT L2 Handoff Optimization

Speeds up handoff procedure (e.g. passing security keys). Requires inter-RAT interface between access gateways

Medium

Inter-RAT Network-Initiated Handoff

Enables operators to enforce handoff policies and decisions. Requires inter-RAT measurement reporting

High

Target Preparation is the Key aspect of Optimized Handovers

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WiMAX Reference Diagram

NAP

ASN CSN

R4

Another ASN

Visited NSP Home NSPR2

R2

R3R1 R5

SS/MS

ASP Network ORInternet

ASP Network ORInternet

CSN

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WiMAX – R4 Expected to get modified for Inter-Tech Handovers Support Handover Messages

– HO_Req– HO_Rsp– HO_Cnf– Context_Transfer– Bearer Path Setup

802.21 HO Messages (HO Flows) should align with those in WMF specs for WiMAX related HOs

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Generic Inter-RAT Interfaces

Mobile Station(MS)

AG-RAT1

AG-RAT2

RAG

Common Core

HAAAA

HSSHLR

Rcore

Rcore

Inter-RATServer

RS

RS

802.21

802.21

WMF-R4

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Conclusions

Providing a complete solution for WiFi<>WiMAX HOs may be the best value add for 802.21 …..in near term– May need to define few more N2N Handover messages

3GPP has some reservations w.r.t IS servers but 3GPP has accepted providing information about 802 networks over 3GPP RANs

Single Radio HO solution is one of the Key Activity in 3GPP– WiMAX<>3GPP/2

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BackUp

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SAE Architecture Enhancements for WiMAX Optimized Handoff

WiMAXASN

WiMAX-R1

SGi

S3

S1-MME

UE

GERAN

UTRAN SGSN

“ LTE - Uu ” E-UTRAN

MME

S5 Serving Gateway

PDN Gateway Operator's IP Services

(e.g. IMS, PSS etc.)

S2a

WiMAX IWF

X101

Sw1 SGi

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Proposed Single-Radio HO Architecture

X200 interface terminates to an FAF Relay X200 based on L3 tunnel X1: between FAF Relay and FAF/MME (both in the same network) UE does NOT need to discover the FAF Relay in the HPLMN (can be provisioned) X101: Used for 3GPP to mobile WiMAX pre-registration & for NW-initiated HO from

mobile WiMAX to 3GPP

PDN GW

S1-MME

S10

MMES11

UE E-UTRAN SGiS1-U

S2aX101

ASN GW

Serving GW

S5

SGSNGERAN / UTRAN

S3

FAF

X200

S4

Mobile WiMAXIP Access

HPLMN

Non-3GPP Networks

FAFRelay

Operator’s IP services

X1

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3GPP to WiMAXUE/ ME

Target WiMAX ASN

Source 3GPP Network

SourceSGSN

WiMAX IWF/MME

Serving GW

HSS/AAA

4a. WiMAX DL Sync

15. Release 3GPP Resources

Uplink & Downlink PDUs (may traverse target SGSN)

5. WiMAX R4 Handover Request

3. IKEv2 Auth & IPSec Setup 3. Authentication & Authorization

6. WiMAX R4 Context Request

7. WiMAX R4 Context Response

9. Proxy Binding Update (PMIP)

10. Proxy Binding Ack (PMIP)

2. Decision to perform HO to WiMAX

4. Handover Request

PDN GW/HA

14. WiMAX PHY/MACEstablishment

1. WiMAX Radio on

13. Handover Command

Uplink & Downlink PDUs

8. WiMAX Resource Preparation

11. WiMAX R4 Handover Response

12. WiMAX R4 Handover Ack

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WiMAX to 3GPPUE/ MS

WiMAX ASN

Target 3GPP Network

TargetSGSN

WiMAX IWF/MME

Serving GW

PDN GW/HA

HSS/AAA

2. Decision to perform HO to 3GPP

3. IKEv2 Auth & IPSec Setup 3. Authentication & Authorization

1. 3GPP Radio on

Uplink & Downlink PDUs

7. Forward Relocation REQ

9. Forward Relocation RES

6. Rest of 3GPP Attach with the target network

15. Handover Complete

18. Release WiMAX Resources

14. Handover Command

11. PMIP Proxy BU/

GTP Create Bearer REQ

13. Create Default Bearer RES

Uplink & Downlink PDUs (may traverse target SGSN)

4. Handover Request

10. Create Default Bearer REQ

12. PMIP Proxy BA/GTP Create Bearer RES

8. Target SGSN prepares 3GPP access network

5. WiMAX R4 Handover Request

16. WiMAX R4 Handover Response

17. WiMAX R4 Handover Ack.