ABSTRACT: This contribution introduces the inter-RAT fast handover solution.

TITLE: Inter-Radio Access Technology Fast Handover

TSG-A WG4

RECOMMENDATION: FYI

Samsung Electronics grant a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner's name any Organizational Partner's standards publication even though it may include all or portions of this contribution; and at the Organizational Partner's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner's standards publication. Samsung Electronics are also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution.This document has been prepared by Samsung Electronics to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on Samsung Electronics . Samsung Electronics specifically reserves the right to amend or modify the material contained herein and to any intellectual property of Samsung Electronics other than provided in the copyright statement above.

DATE: August 27, 2007

Notice

SOURCE: Samsung : BeomSik Bae, Bill Semper bsbae@samsung.com Tel. +82-31-279-5093

b.semper@samsung.com Tel. 972-761-7996

22

Principles

• Single radio operation– Dual radio operation should be supported, but not mentioned in this

material.

• Bi-directional fast handover• Minimum change of legacy system• Common Solution for each scenario

– DO-UMB

– DO/UMB-LTE

– DO/UMB-WiMAX

• Low complexity of terminal

33

Overall issues for Inter-RAT handover

• System measurement (if needed)– Target system information – Measurement report– Handover decision/initiation

• Target system preparation– Method

• Tunneling based

– Steps• MS capability negotiation• Authentication• Session Setup• Radio Resource reservation• Layer 3 path switch

• Handover trigger– Handover trigger– Target system access– Resource removal from source

system

MS BS AGW T-BS T-AGW

1. System measurement

2. Measurement Report

3. Handover decision

4. Target system preparation - MS capability - Authentication - Session setup - Radio Resource reservation - Layer 3 path switch

5. Handover trigger (if needed)

6. Target system access

7. source system resource release

HA

Scope of TSG-C if needed

44

Tunneling approach• Layer 3 tunneling based approach

– MS can use the IP connectivity for communicating with the target system.

– MS should be aware of IP address of the target system node and a tunneling protocol over IP layer should be defined between the MS and the target node.

– A IWU can be introduced as the termination point of the tunneling which has the AN functionality of the target system and is connected to the CN node (e.g., 3GPP SAE S-GW and WiMAX ASN-GW)

– Minimum change of the source system nodes (e.g., DO AN/PCF/PDSN, and UMB eBS/AGW) is required.

• No change can be achieved, but minimum change can be considered to improve the efficiency.

– IETF protocol can be used with minimal modification for tunneling or new tunneling protocol can be designed.

Tunneling approach examples [1]

• UMB to DO

Tunneling approach examples [2]

• DO to UMB

Tunneling approach examples [3]

• DO to 3GPP LTE

Tunneling approach examples [4]

• DO to WiMAX

99

Layer 3 tunneling solution design [1]• Architecture

– IWU (Broker) either has RAN functionality or RAN functionality and also CN functionality• With DO as the target system

– AN and PCF functionality having A10/A11 and A13 interfaces with PDSN and PCF– AN functionality having A8/A9/(A14)/(A20) interface with PCF (legacy AN upgrade)

• With UMB as the target system (FFS)– eBS functionality having U1, U2, and U3 interfaces with AGW, SRNC and eBS respectively

• With 3GPP LTE as the target system– eBS and MME functionalities having S10 and S11 interfaces with MME and Serving GW respectively– eBS functionality having S1 interface with MME

• With WiMAX as the target system– BS and ASN-GW functionality having R4 interface with other ASN-GW– BS functionality having R6 interface with ASN-GW

1010

Layer 3 tunneling solution design [2]

• Handover flow for handover from DO to UMB1. HO is triggered based on the

radio link condition or based on the system information

2. MS discovers the IP address of IWU

3. MS is authenticated by IWU for L3 tunneling (if needed)

4. MS communicates with UMB system via IWU. MS authentication and session negotiation are performed

5. HO decision can be made by MS or network based on the radio link condition or based on some policy

6. IWU may trigger the inter-eBS hard handoff

7. MS accesses UMB eBS

MS

AN SRNCPCF PDSNUMBDO AGW

Route Open

Authentication

HO Indication

L3 Tunnel

Data service over UMB

IWU

IWU Discovery

L3 Tunnel

MS Authentication by IWU (if needed)

HO Decision

L3 Tunnel L3 Tunnel

Data service over DO

Session Negotiation

HO Trigger

eBS

Radio Resource reservation (if needed)

UMB Air access

1111

Layer 3 tunneling solution design [3]

• Handover flow for handover from DO to 3GPP LTE1. HO is triggered based on the

radio link condition or based on the system information

2. MS discovers the IP address of IWU

3. MS is authenticated by IWU for L3 tunneling (if needed)

4. MS communicates with LTE system via IWU. MS capability negotiation, authentication and LTE session setup are performed

5. HO decision can be made by MS or network based on the radio link condition or based on some policy

6. IWU may trigger the handoff7. MS accesses LTE eNB

MS

AN MMEPCF PDSNLTEDO S-GW

MS capability negotiation

Authentication

HO Indication

L3 Tunnel

Data service over LTE

IWU

IWU Discovery

L3 Tunnel

MS Authentication by IWU (if needed)

HO Decision

L3 Tunnel L3 Tunnel

Data service over DO

Session Setup

HO Trigger

eNB

LTE Air access

Radio Resource reservation (if needed)

1212

Layer 3 tunneling solution design [4]

• Handover flow for handover from DO to WiMAX1. HO is triggered based on the

radio link condition or based on the system information

2. MS discovers the IP address of IWU

3. MS is authenticated by IWU for L3 tunneling (if needed)

4. MS communicates with WiMAX system via IWU. MS capability negotiation, authentication and WiMAX session setup are performed

5. HO decision can be made by MS or network based on the radio link condition or based on some policy

6. IWU may trigger the handoff7. MS accesses WiMAX BS

MS

AN ASN-GWPCF PDSNWiMAXDOWiMAX

BS

MS capability

Authentication

HO Indication

L3 Tunnel

Data service over WiMAX

IWU

IWU Discovery

L3 Tunnel

MS Authentication by IWU (if needed)

HO Decision

L3 Tunnel L3 Tunnel

Radio Resource reservation (if needed)

WIMAX Air access

Data service over DO

WiMAX Session Setup

HO Trigger

1313

Layer 3 tunneling solution design [5]

• Study area– When IWU discovery is triggered– Mechanism to get the IP address

of IWU– Authentication mechanism for

IWU– L3 tunneling protocol between UE

and IWU– Separation of IWU from BS– When CMIP/PMIP BU should be

triggered

UE

eNB ASN-GWMME PDN-GWServing-GWWiMAXLTE BS

UE capability

Authentication

HO Indication

L3 Tunnel

Data service over DO

IWU

IWU Discovery

L3 Tunnel

UE Authentication by IWU

HO Decision

L3 Tunnel L3 Tunnel

Radio Resource reservation

WiMAX Air access (Inter BS handover)

Data service over LTE

Session setup

HO Trigger

1414

Analysis of layer 3 tunneling based approach

• Layer 3 tunneling based approach does not need the change of the source system– By introducing a new layer 3 node (which is called IWU in the

previous slide), inter-RAT mobility can be supported without requiring any change of source system

– Only tunneling protocol is newly introduced, so simple.

– Optimized handover from legacy system to the non-3GPP system also can be supported without impact to the legacy system.

– Layer 3 tunneling solution can be the common solution for support any inter-RAT handover (e.g. DO-UMB, DO/UMB-3GPP LTE, DO/UMB-WiMAX)