15.1 Non-Optimized Active Handoff or Idle Mode Mobility
from E-UTRAN to eHRPD using PMIPv6 based S5 and
S2a
The steps involved in the handover from E-UTRAN to eHRPD system are depicted
below for the case of non-roaming, roaming with home routed traffic, roaming with local
breakout and roaming with anchoring in the Serving Gateway in the VPLMN. It is
assumed that while the UE is served by the 3GPP Access, a PMIPv6 tunnel is established
between the S-GW and the P-GW in the evolved packet core. The call flow is based on
the non-optimized handoff procedures for E-UTRAN to non-3GPP access described in
TS 23.402 Clause 8.2.2 Error! Reference source not found.. At the beginning of this
call flow, the UE may be active or idle. This call flow assumes that the UE does not have
a previously established PPP session.
Roaming
Scenario
UE
eNB
MME
eAN/ePCF
HSGW
S-GW
P-GW
3GPP2 AAA
Server/Proxy
vPCRF
hPCRF
HSS/
AAA
PMIPv6 Tunnel
1. Non-optimized
handover initiated
2. S2a attach procedures (see Section 6.4.1) modified for non-optimized handoff as per TS23.402 Clause 8.2.2
PMIPv6 Tunnel
3. Release resourcs in EPS (Binding Revocation) – TS23.402 Section 6.12
4. UE initiated Connectivity to Additional PDNs
Figure 1
E-UTRAN to eHRPD non-optimized handoff between PMIP6 S5 and S2a
1.
The UE is attached to the 3GPP Access and has a PMIPv6 tunnel on the S5 interface.
Non-optimized handover procedures are triggered.
2.
The UE and the eHRPD network perform the steps for eHRPD session establishment and
default PDN bearer establishment. These steps are described in Section Error!
Reference source not found.. If eHRPD session is previously established between UE
and eAN/ePCF, then steps 1 to 5 of Section 6.4.1 are omiited. The following changes are
required to the flow in Section Error! Reference source not found.:
i. Step 8, the VSNCP Config-Req message has the Attach Type set to ‘Handover’
to indicate to the network that the UE has previously established state with the
EPC network.
ii. Step 11, the P-GW executes a PCEF-Initiated IP CAN Session Modification
Procedure with the PCRF as specified in TS 23.203 Error! Reference source
not found.. The Event Report indicates the change in Access Type.
3.
Resources are released in EPS as per TS23.402, clause 6.12 Error! Reference source
not found..
4.
If required, the UE may connect to additional PDNs.
15.4 Non-Optimized Active Handoff or Idle Mode Mobility
from E-UTRAN to eHRPD using PMIPv6 based S5 and
S2a with previously established eHRPD session and
PPP session
The steps involved in the handover from E-UTRAN to eHRPD system are depicted
below. It is assumed that while the UE is served by the 3GPP Access, a PMIPv6 tunnel is
established between the S-GW and the P-GW in the evolved packet core. The call flow
is based on the non-optimized handoff procedures for E-UTRAN to non-3GPP access
described in TS 23.402 Clause 8.2.2 [15]. At the beginning of this call flow, the UE may
be active or idle.
This call flow assumes that the UE has a previously established eHRPD session and PPP
session.
Roaming
Scenario
UE
eNB
MME
eAN/ePCF
HSGW
S-GW
P-GW
3GPP2 AAA
Server/Proxy
vPCRF
hPCRF
HSS/
AAA
1. UE sets up eHRPD session [see Section 6.4.1 & 6.4.4 for default and additional PDN connection setup]
2. UE handoff to E-UTRAN (see Section 15.2 steps 1-3]
PMIPv6 Tunnel
3. Non-optimized handover to eHRPD
initiated
4. UE handoff to eHRPD [See steps 6a to 8c, Section 14.1.2]
PMIPv6 Tunnel
5. QoS updates (if applicable) for previously established flows on eHRPD
6. UE initiated PDN connectivity updates (addition/release of any PDN while UE was active on LTE)
7. Release resources in EPS (Binding Revocation) – TS23.402 Section 6.12
Figure 2
E-UTRAN to eHRPD non-optimized handoff between PMIP6 S5 and S2a
1.
The UE is attached to eHRPD Access. The UE has established PDN connections
using eHRPD access. PMIPv6 tunnel is setup between HSGW and P-GW.
2.
The UE handoff to E-UTRAN. The steps 1 to 3 in Section 15.2 are executed.
HSGW starts a ‘HSGW context inactivity’ timer. HSGW keeps the PDN context
of the UE for each of the PDNs the UE is connected to until the timer expires.
Following steps assume that the ‘HSGW context inactivity’ timer has not expired. If the
timer, then the procedure described in Section 15.1 are executed.
3.
Non-optimized handover from E-UTRAN to eHRPD is triggered.
4.
UE handoff to eHRPD. Steps 6a to 8c of Section 14.1.2 are executed
5.
(Optional) The network initiates QoS update procedures to update the dedicated
bearers on eHRPD based on any changes that might have occurred during the
time while the UE is on E-UTRAN network. If there are no updates to QoS from
the last time QoS was setup on eHRPD access, then this step is not executed.
6.
(Optional) The UE establishes PDN connections on eHRPD access to those
PDNs that are added during the time while the UE was active on E-UTRAN,
and releases the PDN connections on eHRPD access to those PDNs that are
released during the time while UE was active on E-UTRAN. If there are no
updates to PDN connections from the last time the UE sets up PDN connections
on eHRPD access, then this step is not executed.
7.
Resources are released in EPS as per TS23.402, clause 6.12 [15]