Ran2176 Lte Ps Handover

(1)

RAN2176 L

(2)

Introduction

WCDMA – LTE Interworking from WCDMA perspective

UTRA_IDLE Cell_PCH URA_PCH Cell_DCH Cell_FACH RRC_IDLE RRC_CONNECTED

WCDMA - LTE Interworking overview

•

RAN2067 LTE Interworking(RU20 On Top)and RAN3069 RSRQ based LTE Reselection

• The UE, on operator ’s preference, selects to camp on LTE layer based on absolute layers’ priorities once coverage is available.

• RAN3069 introduces quality criteria (Squal related)

•

RAN2176 LTE PS Handover (RU20 On Top)

• Seamless handover of data services to WCDMA when leaving the LTE coverage with minimal interruption time.

• Multi-RAB handover is supported.

•

RAN2435 SRVCC from LTE and CSFB with HO(RU40)

• Single Radio Voice Call Continuity from LTE to W CDMA allows LTE VoIP call to be handed over to WCDMA as a normal CS voice call.

• CS Fallback support (if VoLTE call cannot be setup, for realization of the voice call the UE is handed over to WCDMA for CS connection setup)

•

RAN2717 Smart LTE Layering(RU40)

• Efficient mechanisms for moving active UEs to the LTE layer (RRC Connection Release with Redirection command to LTE).

•

RAN2264 Smart LTE Handover

• WCDMA-LTE outgoing PS handover once LTE coverage is available

•

RAN2980 Measurement based LTE Layering

• Moving active UEs to the LTE layer (measurements of LTE layer are done before redirection command)

(3)

Introduction

WCDMA – LTE Interworking from WCDMA perspective

UTRA_IDLE Cell_PCH URA_PCH Cell_DCH Cell_FACH RRC_IDLE RRC_CONNECTED

WCDMA - LTE Interworking overview

•

RAN2067 LTE Interworking(RU20 On Top)and RAN3069 RSRQ based LTE Reselection

• The UE, on operator ’s preference, selects to camp on LTE layer based on absolute layers’ priorities once coverage is available.

• RAN3069 introduces quality criteria (Squal related)

•

RAN2176 LTE PS Handover (RU20 On Top)

• Seamless handover of data services to WCDMA when leaving the LTE coverage with minimal interruption time.

• Multi-RAB handover is supported.

•

RAN2435 SRVCC from LTE and CSFB with HO(RU40)

• Single Radio Voice Call Continuity from LTE to W CDMA allows LTE VoIP call to be handed over to WCDMA as a normal CS voice call.

• CS Fallback support (if VoLTE call cannot be setup, for realization of the voice call the UE is handed over to WCDMA for CS connection setup)

•

RAN2717 Smart LTE Layering(RU40)

• Efficient mechanisms for moving active UEs to the LTE layer (RRC Connection Release with Redirection command to LTE).

•

RAN2264 Smart LTE Handover

• WCDMA-LTE outgoing PS handover once LTE coverage is available

•

RAN2980 Measurement based LTE Layering

• Moving active UEs to the LTE layer (measurements of LTE layer are done before redirection command)

(4)

LTE PS Handover

Introduction

Brief description

•

Seamless handover of data services to WCDMA when leaving the LTE coverage with minimal interruption time.

•

RAN2176 LTE PS Handover feature accepts incoming interRAT-HO from a UE coming from LTE

•

UTRAN uses complete specification of radio links and radio bearers for the RRC:Handover to

UTRAN message, instead of predefined default configurations

•

Therefore UTRAN has to identify the source of the HO in order to detect that HO comes from LTE

•

UTRAN can detect the source RAT of the incoming HO from:

•

"Source RNC to Target RNC Transparent Container" contained in the incoming RANAP:Relocation Request message. This IE contains "UE History Information" IE.

•

If "UE History Information" contains "Last Visited E-UTRAN Cell Information", then UTRAN

identifies this HO as an incoming HO from LTE

•

Multi-RAB handover is supported.

Once LTE coverage ends, E-UTRAN triggers PS HO

UTRAN accepts relocation ensuring seamless HO of

data services

This feature allows incoming PS Handover for UEs coming from LTE

Without this feature

•

All relocations coming from LTE are rejected.

•

All relocation procedures like PS HO, SRVCC or CSFB fail

•

PS call started in LTE is dropped once user is leaving LTE coverage and there are no means of continuing this call in UTRAN

LTE coverage ends, E-UTRAN triggers PS HO

UTRAN arejects relocation Call is dropped

(5)

LTE PS Handover usage

SRVCC from LTE

•

Handover Preparation cont.

•

CS and PS Core Network sends RANAP:

RELOCATION REQUESTmessages to the Target

RNC in order to allocate the resources. Each of these messages contains an indication of Number of Iu Instances. In this case equals 2.

•

Upon receiving first message and reading this number, the RNC waits for the second message. It may happen that relocation request message from PS comes first.

•

Addmision decision

• RANAP: RELOCATION REQUEST message

containsUE History Information

information element. It indicates E-UTRAN as a last visited cell. The target RNC knows that this is an SRVCC procedure and accepts the request only if the following conditions are satisfied:

• ISHO from LTE license exists

•

RAN2176 LTE PS HO is activated in target cell (parameter

WCEL/IncomingLTEISHOset to

Enabled)

•

RAN2345 SRVCC from LTE and CSFB with HO is activated in the RNC (parameter RNFC/SRVCCEnabledset

toEnabled)

UE Source eNB Target NodeB Target RNC MME Core Network

MSC Server coordinatesPS-CS Handover (SRVCC) Data Bearers are handed over according to existing mechanisms

RANAP: RELOCATION REQUEST from CS

RANAP: RELOCATION REQUEST from PS

Admission decision RELOCATION REQUEST from CS Lastvisited Cell E-UTRAN RNC 1. DoesISHO from LTE license

exists?

2. Is RAN2176 LTE PS HO activated?

3. Is feature RAN2345 SRVCC from

LTE and CSFB with HO activated?

RELOCATION FAILURE If the answer for at least one question is NO

Accept the Relocation Request and start allocating

resources

(6)

LTE PS Handover usage

CSFB with HO

•

Handover Preparation

•

This phase is started once the Source eNB sends

Handover Requiredmessage towars the Mobility

Management Entity (MME). This message contains CSFB indication and generic Source to Target Transparent Container.

•

CSFB indication is included in PS Handover Request message from the MME to the PS Core Network.

•

PS Handover coordination

•

The PS Core Network coordinates PS Handover and sendsRANAP: RELOCATION

REQUESTmessages to the Target RNC in

order to allocate the resources.

•

Addmision decision

• ISHO from LTE license exists?

•

RAN2176 LTE PS HO is activated in target cell (parameter WCEL/IncomingLTEISHOset

toEnabled)?

•

RAN2345 SRVCC from LTE and CSFB with HO is activated in the RNC (parameter

RNFC/CSFBEnabledset toEnabled)?

• In case of CSFB, all PS RABs (RT or NRT) are always allocated to DCH 0/0. DCH/DCH is allocated for SRBs only (based on SRBBitRateRRCSetupEC parameter value related to establishment cause “originating conversational call ”).

UE Source eNB Target NodeB Target RNC MME Core Network

Handover decidion PS Data Service;

Based on trigger, the E-UTRAN makes a decision to iniciate an Inter-technology Handover

PS Handover Request S1-AP: HANDOVER REQUIRED

RANAP: RELOCATION REQUEST from PS

Admission Control Algorithm

Admissio ndecision RELOCATION REQUEST from CS Last visitedCellE-UTRAN RNC

1.Does ISHO from LTE licenseexists? 2.IsRAN2176 LTE PS

HOactivated?

RELOCATION FAILURE Iftheanswerfor atleastonequestionisNO

AccepttheRelocation Requestandstart allocatingresources

Iftheanswerfor allquestionisYES

(7)

LTE PS Handover usage

Licensing

•

The „ISHO from LTE” license controls RAN2176 LTE PS Handover

License Name: ISHO from LTE

License Type: Long-term Capacity

Description:

It is possible to allow incoming LTE Handover (e.g. PS HO, SRVCC, CSFB) when license exists and the state is ON.

•

Upon receving the RANAP: Relocation Request from CS CN due SRVCC from LTE or from PS CN due to CSFB from LTE or from PS CN due to LTE PS

Handover, RNC accepts the request only if the following conditions are

satisfied:

1. License of

„

ISHO from LTE

”

exists and the state is

„On”

.

2. Management parameter

WCEL/IncomingLTEISHO

is set to

Enabled

for the

corresponding target cell under target RNC.

• For PS Handover, if the

IncomingLTEISHO

has value

Disabled

, the relocation is

rejected

• For SRVCC, if the

IncomingLTEISHO

or

SRVCCEnabled

has value

Disabled

, the

relocation is rejected

• For CSFB, if the

IncomingLTEISHO

or

CSFBEnabled

has value

Disabled

, the

relocation is rejected

ISHO from LTE

CAPACITY VALUE

100

ISHO from LTE

CAPACITY VALUE

100

Number of

parameters set toEnabled

84

Number of

parameters set toEnabled

103

Number of activated cells must not exceed the capacity of „ISHO from LTE” license.