Ran15.0 Umts-To-lte Fast Return

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HUAWEI TECHNOLOGIES CO., LTD.

RAN15.0 UMTS-to-LTE

Fast Return

Author/Email: zhangdaliang 00164806

Version:V1.0(20121221)


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HUAWEI TECHNOLOGIES CO., LTD. Page 3HUAWEI Confidential

Background

Introduction

Deployment

Performance Monitoring

Acronyms and Abbreviations

Contents


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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.

LTE UMTS

CS call


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Background

Introduction

Deployment

Performance Monitoring


Contents


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Introductionprinciple

Fast Return (RRC

connection releasewith LTE

frequency)

UMTS

LTE

When the voice call is complete in UMTS, the RNC sendsfrequencies for neighboring LTE cells to the UE so that the UEcan fast camp on a suitable LTE cell.

Without fast return (8s)

With fast return (400 ms)

CSFB to

UMTS

CS call is

complete.

Cellreselection

Camp on

LTE

Fast return

CSFB

The time required for the UE to return from the serving UMTS

network to the LTE network decreases from 8s to 400 ms.

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 UMTScell.

Frequency source: LTE frequencies carried in system information

block 19 (SIB19)

UE: Huawei E392 (a data card)


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Introductionspecify a CSFB user

Satisfy one of the conditions below

1. The cause value inthe RELOCATION RQEUSET message is CSFallback triggered

2. The information element (IE) CSFB Informationcarried in RELOCATION

REQUEST message is set to CSFBor CSFB High Priority

3. Meets all the conditions below 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 Indicationis carried in RRC CONNECTION REQUEST

message

5. The IE End of CSFB is carried in IU RELEASE COMMAND message.


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Background

Introduction

Deployment

Performance Monitoring Acronyms and Abbreviations

Contents


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

Mutually Exclusive Features None

Impacted Features None

Hardware

None NEs

When UEs are redirected to UMTS due to CSFB, UEs must comply with 3GPP Release

9.4.0, or MSC can sent IU RELEASE COMMAND with IE End Of CSFB.

When a UE in LTE is handed over to UMTS due to CSFB, the cause value in the

RELOCATION RQEUSET message sent to the RNC is CS Fallback triggered (268), or

the IE CSFB information carried in the message is set to CSFBor CSFB High Priority, orMSC can sent IU RELEASE COMMAND with IE End Of CSFB .

License An RNC-level license control item has been introduced on the RNC side to accommodate

the UMTS-to-LTE Fast Return feature. Note that the feature is optional.

Prerequisites


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Activation

Switches in RNC Select HO_UMTS_TO_LTE_FAST_RETURN_SWITCHunder the HandOver Switchparameter in RNC

MML command SET UCORRMALGOSWITCH.

Select PERFENH_PS_FAST_RETURN_LTE_SWITCHunder the Performance Enhancement Switch 3

parameter in RNC MML command SET UCORRMPARA.

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

Select PERFENH_PS_FAST_RETURN_LTE_SWITCH andHO_UMTS_TO_LTE_FAST_RETURN_SWITCH under the Fast Return To LTE Switch parameter in CELL

MML command MOD UCELLHOCOMM.

If the feature 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

Switches in RNC(they are effective only when cell MML commandADD UCELLHOCOMM

is not configured)

Deselect HO_UMTS_TO_LTE_FAST_RETURN_SWITCH under the HandOver Switch

parameter in RNC MML command SET UCORRMALGOSWITCH.

Deselect PERFENH_PS_FAST_RETURN_LTE_SWITCH under the Performance

Enhancement Switch 3parameter in RNC MML command SET 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.


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Background

Introduction

Deployment


Contents


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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 toreturn from

UMTS to LTE


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New Counters

None


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Background

Introduction

Deployment


Contents


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CSFB: CS fallback

PS HO: packet service handover


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Copyright 2013 Huawei Technologies Co., Ltd. All Rights Reserved.

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constitutes neither an offer nor an acceptance. Huawei may change the information at any time without notice.

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Ran15.0 Umts-To-lte Fast Return

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