1 | l2-tunnel based – inter-tech. ho | october 29, 2007 title: an l2-tunnel based method for...

1 | L2-Tunnel based – Inter-tech. HO | October 29, 2007

Title: An L2-Tunnel based method for UMB-HRPD Inter-Technology handoff

Source: Alcatel-Lucent, Nortel, AirvanaAbstract:This contribution proposes a mechanism for UMB-HRPD inter-technology handoff using a tunnel across the radio interface to the source RAN, and another tunnel between the source and target RANs.

Proposal:Review and approve L2 tunneling as the architectural approach for UMB-HRPD handoffs.

3GPP2 A40-20071029-004r0

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OUTLINE

Background Objectives Mechanism for data tunneling Inter- RAT Module - Reverse link Inter- RAT Module - Forward link


BackgroundSeamless handovers must be supported when there are mobiles

with two radios and when there is only a single radio.

Each access technology must be able to evolve without impacting the ability to perform seamless handover with other access technologies.

A mechanism must be available for the RAN of one access technology to communicate with the RAN of a different access technology. As we have found in the HRPD-1x handoff over A21, the ability of two RANs to exchange not only HO signaling, but also status information and radio parameters is a significant means of managing and optimizing inter-RAN handoffs.

Network control of handoffs is a major requirement for many operators.

The source RAN and target RAN must both be involved in the control of the handoff; the source RAN to command that it take place and to manage the handoff, the target RAN to establish resources.


UMB-DO handoff: ObjectivesMinimize interruption to active call during handoff

Minimize changes to deployed networks like HRPD

Ability for Network control/direction of the handoff

Commonality with handoff mechanisms between other pairs of technologies


Mechanism for data tunneling The HRPD security layer packet is tunneled between the

SRNC and the AT via the session anchor route using IRTP.

The HRPD signaling is tunneled between the SRNC and the HRPD AN/PCF.


Inter- RAT Module - Reverse link In the mobile, the Inter-RAT module add its headers to the

HRPD Security-layer packet (Inter RAT Payload) which may include the following information to form the Inter– RAT packet to be tunneled to the target (HRPD) RAN

Target Technology, Target ANID, AT Index

The Inter-RAT packet is tunneled to the Session Anchor AN using IRTP.

Based on the IRTP header information the Session Anchor AN passes the IRTP payload (Inter-RAT packet) to its Inter-RAT module.

The Inter-RAT module based on the information in the received packet header (Inter-RAT packet) sends the packet on the appropriate Inter-RAT tunnel to an HRPD AN/PCF.

On the receipt of the tunneled packet at the Inter- RAT module of target (HRPD) RAN, the Inter-RAT payload (HRPD Security layer packet) is forwarded to the Security layer for processing.


The HRPD AN sends the HRPD Security-layer packet (Inter RAT Payload) to the Inter-RAT module.

The Inter-RAT module adds headers to the HRPD Security-layer packet (Inter RAT Payload) which may include the following information to form the Inter– RAT packet to be tunneled back to the mobile.

Target Technology, Target ANID, AT Index

The Inter-RAT packet is tunneled to the Source (UMB) RAN via Inter-RAT tunnel.

The Inter-RAT packet is tunneled to the mobile using IRTP.

At the mobile the IRTP payload (Inter- RAT packet) is forwarded to its Inter-RAT module.

The Inter-RAT module forwards the Inter-RAT payload (HRPD Security layer packet) to the HRPD Security layer.

Inter- RAT Module - Forward link


Issue: SRNC transfer (source new) occurs while handoff is in progress. Two Possible Solutions:

Lock the SRNC to avoid transfer Or:

The Inter-RAT packets from the mobile will be sent via the Inter –RAT tunnel between the new SRNC and the HRPD RAN.

Upon the receipt of IAS-UATI Update from target SRNC the Inter-RAT module at the Source SRNC forwards any Reverse Link in-flight Inter-RAT packets to the Inter-RAT module at the target SRNC.

The Inter-RAT header may include a token number which helps the HRPD RAN in selecting the Inter-RAT tunnel towards UMB RAN for sending the forward link Inter-RAT packets.

The token number used by source SRNC shall be passed to the new SRNC. The Inter-RAT module at new SRNC shall increment this and use it while sending packets over its Inter-RAT tunnel with the HRPD RAN.

HRPD RAN shall send data for mobile on the Inter-RAT tunnel to UMB SRNC from which it received Inter-RAT packet with the highest token number.

Issue and Possible Solutions


Thanks!

1 | l2-tunnel based – inter-tech. ho | october 29, 2007 title: an l2-tunnel based method for...

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