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www.huawei.com
23/4/20
Non-optimized Handoff Enhancement
HUAWEI Zhiming Li [email protected] Jie Zhao [email protected]
13 September. 2010
NoticeThe contributors grants a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner’s name any Organizational Partner’s standards publication even though it may include all or portions of this contribution; and at the Organizational Partner’s sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner’s standards publication. The contributors are also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution.This document has been prepared by the contributors to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on the contributors. The contributors specifically reserves the right to amend or modify the material contained herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to any intellectual property of the contributors other than provided in the copyright statement above.
China Telecom Chengli Mei [email protected]
Ericsson Ahmad Muhanna [email protected] Ke-Chi Jang [email protected]
slide 2
Motivation
Enabling eHRPD-LTE dual mode UE to early-register on eHRPD
directly over eHRPD access.
slide 3
Working assumptions and Key Features
Assumption Based on Single Transmitter / Dual Receiver (1T/2R) UE or Single Transmitter /
Single Receiver (1T/1R) UE Minimizes changes to the current standards and network elements
Key Features – (1T/1R) UE Step 1: UE selects and camps on LTE first without any interaction with eHRPD
system Step 2: UE performs eHRPD early-registration directly over eHRPD access during
LTE idle state. Step 3: UE could maintain eHRPD session during LTE idle state Step 4: Handover Phase – UE HO from LTE to eHRPD
Key Features – (1T/2R) UE Step 1: UE can camp on either LTE or eHRPD first. Step 2: UE performs eHRPD early-registration directly over eHRPD access:
During idle state if camped on LTE first. If UE camp on eHRPD first, UE may perform early-registration on eHRPD first and then move
to LTE. Step 3: UE should be able to maintain eHRPD session during LTE idle state Step 4: Handover Phase – UE HO from LTE to eHRPD in case the UE camps on LTE
first.
slide 4
Early-Registration over eHRPD Access Call Flow(UE camps on LTE first)
UE eAN/ePCF AN-AAA HSGW HSSP-GWPCRF AAAS-GW
1 . Power on
PMIPv6 Tunnel
2 . LTE Initial Attach
4 . eHRPD Session Negotiation, PPP setup and Authentication
9 .
5 . - Req (PDN-ID, Attach Type…)
. VSNCP Config- Ack ( PDN-ID…)
. VSNCP Config- Ack (PDN-ID)
. VSNCP Config- Req ( PDN-ID)
UE initiates eHRPD connection release into dormant state
VSNCP Config
6
8
7
3. UE enters LTE idle state, discovers eHRPD network and tunes to eHRPD network
UE powers on
UE finds a candidate cell of LTE
UE camps on the LTE network
UE switches to eHRPD network and performs early-registration
over eHRPD access
UE switches back to LTE
UE stays in idle and finds a candidate eHRPD cell
UE stays in idle and finds a candidate eHRPD cell
UE stays in idle and finds a candidate eHRPD cell
10. UE Switches
back to LTE
,
If Attach Type = “Registration”, HSGW does not setup bearer path with P-GW. Only default PDN connection must to be setup. The UE can optionally establish non-default PDN connection
If eNB broadcasts the eHRPD Neighbor cell list, the UE will tune to eHRPD mode to perform session establishment when the UE is in LTE idle state.
UE and HSGW can negotiate the capability of early-registration over eHRPD access during LCP
slide 5
Details of early-Registration
Upon receiving the eHRPD neighbor cell list broadcasted by eNB, UE
initiates early-registration directly over eHRPD access.
UE and HSGW negotiate the capability of early-registration over eHRPD
access during LCP. If the HSGW doesn’t support it, UE may terminates the
PPP session setup.
UE establishes the default PDN connection with HSGW. The new attach
type “Registration” indicates that no PMIP tunnel needs to be setup.
UE can optionally establish the non-default PDN connections with HSGW.
slide 6
Roaming Cases Analysis Network
Capability
UE
Capability
non-optimized
handoff with
early-
registration.
Normal non-
optimized handoff
Optimized handoff
(S101)
Optimized handoff
(S101) and non-
optimized handoff
with early-
registration
non-optimized handoff
with early-registration
Non-optimized
with early-
registration
early-registration
attempt no PPP
context
early-registration
attempt no PPP
context
Non-optimized with
early-registration
Normal non-optimized
handoff
Normal Non-
optimized
handoff
Normal Non-
optimized handoff
Normal Non-
optimized handoff
Normal Non-
optimized handoff
Optimized handoff
Support Registration
over S101
Normal Non-
optimized
handoff
Normal Non-
optimized handoff
Optimized Handoff
using S101
Optimized Handoff
using S101
Optimized handoff and
non-optimized handoff
with early-registration
Non-optimized
with early-
registration
Normal Non-
optimized handoff
Optimized handoff
using S101
Optimized Handoff
using S101
slide 7
PPP Session Maintenance
Full PPP context The UE and the HSGW have full PPP context after the early registration The HSGW supports PPP inactivity timer, and the UE knows the MAX PPP Inactivity Timer
value For dual receiver case, UE may receive the LCP Echo-Request from HSGW, and sends Echo-
Reply in idle state For single receiver case, if the UE fails to reply the Echo-Request, the HSGW and the UE
enter to partial UE context
Partial UE context The HSGW supports UE Context Maintenance timer If UE requests one or more PDN connections, HSGW stops the UE Context Maintenance
timer, and re-start the PPP inactivity timer How the UE and the HSGW maintain the partial context, as currently documented in X.S0057
If PPP inactivity timer expires and the UE is NOT able to send any activity, the UE should assume that
the context is gone. However, the UE always can check on the context when goes to eHRPD by sending
echo-request with PDN-ID to check if the HSGW still maintains that context
slide 8
Handover Call FlowUE eAN/ePCF S-eAN HSGW HSSP-GWPCRF
10. PMIP Binding Update
11. PMIP Binding Ack
AAA
3. UATIAssignment + TCA
1. ConnectionRequest
2. A13 Session Transfer
0. Decision to handover to eHRPD
5. A11'-Registration Request
OPTIONAL PROCEDURE
S-GW
17. 3GPP EPS Resource release
4. UATIAssignmentComplete + TCC
OPTIONAL PROCEDURE16. Other PDN connection Setup
15. Network Initiated Dedicated Bearer Setup
OPTIONAL PROCEDURE
6. A11'-Registration Reply
9. VSNCP Config-Req (PDN-ID(s), Attach Type (Handover))
12. VSNCP Config-Ack (PDN-ID…)
13. VSNCP Config-Req (PDN-ID)
14. VSNCP Config-Ack (PDN-ID)
7. LCP Echo Req/Reply (Active PDN(s))
8. Retrieve context from HSS
If Attach Type = “Handover”, HSGW initiates PMIP procedure based on all PDN context received during early registration
slide 9
The details of Handover (1/2)
Full PPP context If UE setups multiple PDN connections during early registration, UE will send one
VSNCP message with “Handoff” attach type and PDN-ID(s) to trigger the HSGW
perform PMIP procedure. UE initiates the TFT process
Partial UE context UE establishes all PDN connections UE initiates the TFT process
No PPP context UE establishes the PPP session UE initiates the TFT process
slide 10
The details of Handover (2/2)
PMIP trigger HSGW doesn’t trigger the PMIP Binding when the HSGW receives A11-Registration
Request message with Active-Start Airlink Record. It is little different from current spec. Upon receiving the VSNCP with attach type = handover and one or more PDN-ID from UE,
HSGW shall trigger the PMIP Binding
PDN Synchronization The UE doesn’t need to keep the PDN connections information which is in eHRPD is
synchronized with one’s in LTE all the time, UE only update the PDN connections
information in eHRPD when it is in idle state in LTE UE shall perform the PDN connections information synchronization with HSGW via LCP
echo during handover
Accounting For the early-registration and session maintenance, the HSGW doesn’t start accounting
process
slide 11
Deployment Consideration & Standards Impacts
Node Deployment impacts Standard impacts
eNB eNB needs to broadcast SIB8, including eHRPD
related cell parameters and subnet info
None
MME None None
SGW None None
eAN/
ePCF
Legacy AN needs to be software upgraded to evolved
AN/ePCF
None
HSGW Needs to support an additional attach type ”
Registration”
Add one new Attach type “Registration” in
VSNCP Config-Req message. (X.S0057)
HSS Should be deployed to support the SWx interface None
AAA . Need to support STa and SWx for authentication &
authorization.
. Need to support S6b.
None
PDN GW Need to support S6b None
PCRF None None
UE Needs to support an additional attach type ”
Registration”
Add one new Attach type “Registration” in
VSNCP Config-Req message. (X.S0057)
slide 12
Recommendation
Adopt the early-registration over eHRPD access
solution in X.P0057 -A
slide 13
BackupInformative Only
slide 14
eHRPD Session Maintenance – KeepAlive Procedures
UE eAN/ePCF eNB S-GW P-GW
3. KeepAliveRequest
4 KeepAliveResponse
2. If UE is in LTE idle state, then tunes to eHRPD network; if UE is in active state, the UE either defers the KeepAlive request until turns to idle state, or tunes to eHRPD directly under the case described in next page
5. UE switches back to LTE
1. UE on LTE
slide 15
The details of KeepAlive Process
Concept: If UE is in Active state, it will set a flag and wait until getting to idle state, at which
time UE will switch to eHRPD to maintain the session.
Details: UE keeps a counter NKeepAliveReq. The counter increase by one when UE detects a
period of eHRPD’s inactivity for TSMPClose/NSMPKeepAlive minutes.
Case 1: If 0< NKeepAliveReq < NSMPKeepAlive, UE will set a flag. When UE enters LTE idle
mode and the flag is set, UE will tune to eHRPD and send KeepAliveRequest message. Reset NKeepAliveReq to 0 and reset the flag.
Case 2: If NKeepAliveReq = NSMPKeepAlive, UE has two options: 1) UE immediately tune to eHRPD and send KeepAliveRequest message. Reset NKeepAliveReq to
0 and reset the flag. In this scenario, the service in LTE is interrupted. 2) UE gives up the eHRPD session maintenance, just keep the service in LTE
NSMPKeepAlive is set to max 3 per C.S0024.
slide 16
eHRPD Session Maintenance – Subnet Change
UET-eAN/ePCF
4. UATI Assignment procedure
HSGW S-GW P-GW
2b. QuickConfig & SectorParameters
Subnet change, tune on eHRPD and perform UATI Assignment
procedure
S-eAN/ePCF
4. A13 Session Transfer
3. UE is in LTE idle state and tunes
to eHRPD
5. UE switches back to LTE
1. UE on LTE
7. Release A10 connection
6. Establish A10 connection
eNB
2a. SIB8(ZoneId)
Note1: For the single receiver case, UE may receive the subnet info from the eNB
Note2: For the dual receiver case, if QuickConfig or SectorParameters message received while UE in LTE active mode,
the UE will defer UATI Assignment to when it goes into LTE idle state
slide 17
LTE Paging and UL Data Process early-registration phase
For the dual receiver case, UE may receive Paging message LTE Stop/abort HRPD registration procedures and tune to LTE
Uplink Data ready for Transmission Stop/abort HRPD registration procedures and tune to LTE
KeepAlive For the dual receiver case, UE may receive Paging message LTE
Continue HRPD KeepAlive procedure and tune to LTE Uplink Data ready for Transmission
Buffer data. Complete HRPD KeepAlive procedure and tune to LTE Subnet change
For the dual receiver case, UE may receive Paging message LTE Stop/abort HRPD UATI Assignment procedures and tune to LTE
Uplink Data ready for Transmission Stop/abort HRPD UATI Assignment procedures and tune to LTE
PPP context maintenance For the dual receiver case, UE may receive Paging message LTE
Stop/abort HRPD registration procedures and tune to LTE Uplink Data ready for Transmission
Stop/abort HRPD registration procedures and tune to LTE