irat handover
TRANSCRIPT
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