Proprietary and Confidential

IRAT HandoverIRAT Handover

Northeast RAN Performance

IRATIRAT

• IRAT handover was successfully tested on 01/09/06 in the UMTS FOA network in Queens.

• All UMTS cells except for BQU4363C was locked for testing.• Call was originated on BQU4363C and then handover to

BQ04744B was performed.

IRAT Handover – Site LocationIRAT Handover – Site Location

3G Cell BQU4363C

2G Cell BQ4744A and BQ4744B

Site Address:

77-16 101st Ave, Queens, NY

For 3G: Only BQU4363C needs to be on-air and the remaining cells should be off.

UMTS & GSM Cell InformationUMTS & GSM Cell Information

3GSector Scrambling Code Cell ID LAC RNC MSC

BQU4363A 76 28631 52153 NYRNC003 NYMSS900BQU4363B 84 28632 52153 NYRNC003 NYMSS900BQU4363C 92 28633 52153 NYRNC003 NYMSS900

2GSector BCCH BSIC Cell ID LAC BSC MSC

BQ04744A 594 45 27441 32121 112 NYMSC04BQ04744B 601 07 27442 32121 112 NYMSC04BQ04744C 606 62 27443 32121 112 NYMSC04

Active Set – Ec/Io

UMTS Call Initiated

Handover completed to GSM

Handover Command from RNC to UE

RSCP: -102dBm

Ec/Io: -5 dB

UE starts compressed mode measurements to start measuring GSM neighbors

RSCP: -96dBm

Ec/Io : -4 dB

Event 2d: When estimated quality of currently used freq is below a certain threshold, UE sends a event 2d to SRNC, which on receiving this message asks the UE to set up event 3a

IRAT Events

Contd…

RNC send a Physical channel reconfiguration message to UE which tells the UE to enter compressed mode to measure GSM neighbor cells.

The method to induce compressed mode is SF/2

IRAT Events Contd..

Contd…

IRAT Events Contd..

Event 3a -> Event trigger for IRAT; RNC asks UE to report GSM neighbors fulfilling a minimum criteria for signal quality

Time to trigger: 100 s

UE sends a measurement report to RNC reporting the RSSI measurements of all the GSM neighbors fulfilling the criteria

IRAT Events Contd..

Handover to GSM command sent by RNC to UE

IRAT handover successfully completed. A more detailed analysis will be done for parameter optimization and to control IRAT boundaries as part of FOA

IRAT Analysis – RNC LogIRAT Analysis – RNC Log

• The figure shows the IRAT handover sequence

• A brief analysis of the corresponding RNC log is attached with all the messages showing the successful IRAT HO.

RNC Log analysis

Path ForwardPath Forward

• For this IRAT testing, the UMTS network was changed to 2 digit MNC – the same as the 2G network.

• After the testing, the UMTS network was reverted back to 3 digit MNC.

• The way forward is to standardize the MNC length to ensure that both UMTS and GSM networks have the same length MNC for successful IRAT handovers.

AppendixAppendix

Tables illustrating the concept of Handover events 2d and 3a related to IRAT.

Taken from Ericsson ALEX library