LTE S1 Handover过程中信息交互

 

Msg Name

Entities

Comment

RRC: MeasurementReport

UE->eNB

measConfig settled in ConnectionReconfiguration

S1AP: Handover Required

SeNB->MME

HO UE and Target Info & Source to Target transparent container

S1AP: Handover Request

MME->TeNB

Include E-RABs, UE security, Source to Target transparent container etc

TeNB alloc resource for admitted E-RABs

S1AP: Handover Request Acknowledge

TeNB->MME

Failed and admitted E-RABs, Target to Source transparent container included

S1AP: Handover Command

MME->SeNB

E-RAB (forward & release) list, Target to Source Transparent container

RRC: ConnectionReconfiguration

SeNB->UE

MobilityControlInfo included notifying UE for handover; This message includes target eNB’s config

S1AP: eNB Status Transfer

SeNB->MME

PDCP SN receiver and transmitter status included

S1AP: MME Status Transfer

MME->TeNB

PDCP SN receiver and transmitter status included

Msg1-2 (Msg3 if contention based)

TeNB<->UE

RACH (done right after ConnectionReconfig received, parallel with S1AP msg exchange)

RRC Connection Reconfiguration Complete

UE-> TeNB

Send in UL data to confirm the handover

S1AP: Handover Notify

TeNB->MME

Notify MME UE arrived, S1 handover complete

S1AP: UE Context Release Command

MME->SeNB

Notify source eNB to release UE context

S1AP: UE Context Release Complete

SeNB->MME

release all related signalling and user data transport resources

 

 

 

 

Note: Messages among MMEs and other EPC entities are ignored here