Ran2176 Lte Ps Handover

RAN2176 LTE LTE PS Handover 

Introduction WCDMA  – LTE Interworking from WCDMA perspective

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

WCDMA - LTE Interworking overview

• 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) Cell_DCH

RRC_CONNECTED

• 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) Cell_FACH

• 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.

Cell_PCH

• 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)

URA_PCH

• RAN2717 Smart LTE Layering

(RU40)

• Efficient mechanisms for moving active UEs to the LTE layer  UTRA_IDLE

RRC_IDLE

(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)

Introduction WCDMA  – LTE Interworking from WCDMA perspective

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

WCDMA - LTE Interworking overview

• 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) Cell_DCH

RRC_CONNECTED

• 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) Cell_FACH

• 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.

Cell_PCH

• 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)

URA_PCH

• RAN2717 Smart LTE Layering

(RU40)

• Efficient mechanisms for moving active UEs to the LTE layer  UTRA_IDLE

RRC_IDLE

(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)

LTE PS Handover  Introduction

Brief description

This feature allows incoming PS Handover for UEs coming from LTE

• 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

Once LTE coverage ends, E-UTRAN triggers PS HO

UTRAN accepts relocation ensuring seamless HO of data services

• 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.

Relocation procedure fails

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, EUTRAN triggers PS HO

UTRAN arejects relocation Call is dropped

LTE PS Handover usage SRVCC from LTE

• Handover Preparation cont. • CS and PS Core Network sends RANAP: UE

Source eNB

Target NodeB

MME

Target RNC

RELOCATION REQUEST messages to the Target

Core Network

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

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

RANAP: RELOCATION REQUEST from CS

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 contains UE History Information

•

RANAP: RELOCATION REQUEST from PS

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:

RNC RELOCATION REQUEST from CS Lastvisited Cell EUTRAN

1.

Does ISHO from LTE license exists?

2. 3.

Is RAN2176 LTE PS HO activated? Is feature RAN2345 SRVCC from LTE and CSFB with HO activated?

 ISHO from LTE license exists

•

Admission decision

Accept the Relocation Request and start allocating resources

• RAN2176 LTE PS HO is activated in target cell (parameter  WCEL/IncomingLTEISHO set to Enabled)

• RAN2345 SRVCC from LTE and RELOCATION FAILURE

If the answer for at least one question is NO

If the answer for allquestion is YES

CSFB with HO is activated in the RNC (parameter RNFC/SRVCCEnabled set to Enabled)

LTE PS Handover usage CSFB with HO

• Handover Preparation • This phase is started once the Source eNB sends UE

Source eNB

MME

Target RNC

Target NodeB

Core Network

Handover Required message towars the Mobility

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

PS Data Service;

• CSFB indication is included in PS Handover Request

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

message from the MME to the PS Core Network. Handover decidion Handover preparation

• PS Handover coordination • The PS Core Network coordinates PS Handover and sends RANAP: RELOCATION REQUEST messages to the Target RNC in order to allocate the resources.

S1-AP: HANDOVER REQUIRED

PS Handover Request

• Addmision decision  ISHO from LTE license exists?

•

RANAP: RELOCATION REQUEST from PS

Admission Control Algorithm

• RAN2176 LTE PS HO is activated in target cell (parameter WCEL/IncomingLTEISHO set to Enabled)?

• RAN2345 SRVCC from LTE and CSFB with HO is activated in the RNC (parameter  RNFC/CSFBEnabled set to Enabled)?

RNC RELOCATION REQUEST from CS Last

visited CellE-UTRAN

1. Does  ISHO from LTE licenseexists?

2. IsRAN2176LTEPS HOactivated?

Iftheanswerfor atleastonequestionisNO

RELOCATION FAILURE

AccepttheRelocati on Requestandstart allocatin gresources

Admissio ndecision

Iftheanswerfor allquestionisYES

• 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 ”).

LTE PS Handover usage Licensing

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

• Upon receving the RANAP: Relocation Request from CS CN due SRVCC from

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.

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.

ISHO from LTE CAPACITY VALUE

100

Number of  WCEL/IncomingLTEISHO parameters set to Enabled 

84

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

• 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

Number of  WCEL/IncomingLTEISHO parameters set to Enabled 

103