Ran15.0 Umts-To-lte Fast Return

 

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RAN15.0 UMTS-to-LTE Fast Return www.huawei.com

 Author/Email: zhangdaliang zhangdaliang 00164806 Version:  V1.0(20121221) Version: V1.0(20121221) HUAWEI TECHNOLOGIES CO., LTD.

 

Contents •

Background

•

Introduction

•

•

Deployment Performance Monitoring

•

 Acronyms and Abbreviations Abbreviations

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Background 

The circuit switched fallback (CSFB) applies to scenarios where UMTS and LTE are deployed together. The LTE network does not support voice services. Therefore, when a UE initiates a voice service on the LTE network, it will fall back to the UMTS network. When the voice service is complete, the UE can fast return to the LTE network from the serving UMTS network, improving user experience.

CS call

LTE

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UMTS

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Contents 

Background



Introduction



Deployment



Performance Monitoring



 Acronyms and Abbreviations

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Introduction——principle 

When the UE's voice service is complete, RRC Connection Release message is sent to UE containing frequencies for neighboring LTE cells whose priorities are higher than the priority of the serving UMTS cell.

LTE



Frequency source: LTE frequencies carried in system information block 19 (SIB19)

Without fast return (8s) Fast Return (RRC connection release with LTE frequency)

CSFB

Cell reselection CSFB to UMTS

Camp on LTE

CS call is complete. Fast return

UE: Huawei E392 (a data card) With fast return (400 (400 ms) ms)

UMTS When the voice call is complete in UMTS, the RNC sends frequencies for neighboring LTE cells to the UE so that the UE

The time required for the UE to return from the serving UMTS network to the LTE network decreases from 8s to 400 ms.

can fast camp on a suitable LTE cell.

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Introduction——specify a CSFB user 

Satisfy one of the conditions below 1. The The c cau ause se valu value e in the RELOCATION RQEUSET message is CS

Fallback triggered  2. The The in info form rmat atio ion n ele eleme ment nt (I (IE) E) CSFB Information carried in RELOCATION

REQUEST message is set to CSFB CSFB or  or CSFB High Priority  Priority  3. Meets Meets all all the con condit dition ions s belo below w 

RRC CONNECTION REQUEST message does not carry the IE pre-

redirection. 



UE supports E-UTRA TDD or E-UTRA FDD.  A CS call is successfully setup within 10s after RRC connection setup complete.

4. The IE CSFB Indication is carried in RRC CONNECTION REQUEST message 5. The IE End of CSFB is carried in IU RELEASE COMMAND message. HUAWEI TECHNOLOGIES CO., LTD.

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Contents 

Background



Introduction



Deployment



Performance Monitoring



 Acronyms and Abbreviations

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Prerequisites 

Prerequisite Features 



Mutually Exclusive Features 



None

Hardware 



None

Impacted Features 



The LOFD-001033 CS Fallback to UTRAN feature has been enabled on the LTE network.

None

NEs 



When UEs are redirected to UMTS due to t o CSFB, UEs must comply with 3GPP Release 9.4.0, or MSC can sent IU RELEASE COMMAND with IE End Of CSFB. CSFB. When a UE in LTE is handed over to UMTS due to CSFB, the cause value in the RELOCATION RQEUSET RQEUSET message sent to the RNC is CS Fallback triggered (268), or the IE CSFB information carried in the message is set to CSFB CSFB or  or CSFB High Priority, or MSC can sent IU RELEASE COMMAND with IE End Of CSFB .



 License 

 An RNC-level license control item has been introduced on the RNC RNC side to accommodate the UMTS-to-LTE Fast Return feature. Note that the feature is optional.

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Activation 

Switches in RNC 

Select HO_UMTS_TO_LTE_FAST_RETURN_SWITCH HO_UMTS_TO_LTE_FAST_RETURN_SWITCH under  under the HandOver Switch parameter Switch parameter in RNC MML command SET UCORRMALGOSWITCH. UCORRMALGOSWITCH.



 under the Performance Enhancement Switch 3  Select PERFENH_PS_FAST_RETURN_LTE_SWITCH PERFENH_PS_FAST_RETURN_LTE_SWITCH under 3  parameter in RNC MML command SET UCORRMPARA. UCORRMPARA.



Switches in cell(if they are configured, switches in RNC are out of service) 

Select PERFENH_PS_FAST_RETURN_LTE_SWITCH and HO_UMTS_TO_LTE_FAST_RETURN_SWITCH under the Fast Return To LTE Switch parameter in CELL MML command MOD UCELLHOCOMM.  UCELLHOCOMM. 



If the feature feat ure has been activated, the RNC sends the UE an RRC Connection Release message carrying the IE Redirection info, which contains frequencies for neighboring LTE cells after the UE's RRC connection is released in UMTS.

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Deactivation 

UCELLHOCOMM c ell MML command ADD command ADD UCELLHOCOMM Switches in RNC(they are effective only when cell is not configured) 



Switch  Deselect HO_UMTS_TO_LTE_FAST_RETURN_SWITCH  under the HandOver Switch  parameter in RNC MML command SET UCORRMALGOSWITCH. UCORRMALGOSWITCH. Deselect PERFENH_PS_FAST_RETURN_LTE_SWITCH  under the Performance Enhancement Switch 3  3 parameter in RNC MML command SET UCORRMPARA. UCORRMPARA.



Switches in cell(if they are configured, switches in RNC are out of service) 

Deselect PERFENH_PS_FAST_RETURN_LTE_SWITCH and HO_UMTS_TO_LTE_FAST_RETURN_SWITCH  under the Fast Return To LTE Switch parameter in CELL MML command MOD UCELLHOCOMM.  UCELLHOCOMM. 

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Contents 

Background



Introduction



Deployment



Performance Monitoring



 Acronyms and Abbreviations

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Gains 

Query the time required for UEs to return from UMTS to LTE from UE logs. The time is the interval at which the UE receives the RRC CONNECTION RELEASE message and sends the RRC CONNECTION REQUEST message.



If the time is shorter than that before the UMTS-to-LTE Fast Return feature is enabled, this feature yields positive gains.

Time required for UEs to return from UMTS to LTE

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New Counters 

None

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Contents 

Background



Introduction



Deployment



Performance Monitoring



 Acronyms and Abbreviations

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Acronyms and Abbreviations 

CSFB: CS fallback



PS HO: packet service handover

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