Transcript WiMAX-3GPP Optimized Handover

IEEE 802.21 MEDIA INDEPENDENT HANDOVER
DCN: 21-07-0351-00-0000
Title: Inter-Tech Handover Activity
Date Submitted: September, 2007
Presented at IEEE 802.21 session #22 Big Island
Authors or Source(s):
Vivek Gupta
Abstract: Update on Handover activities across SDOs
and messages/directions for 802.21
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802.21 How we Started ?
 Optimize L3 Handovers
– Network Discovery & Selection (ND&S)
– Enable Network initiated Handovers
– Lower Power Operation
 Assumptions:
– Dual Radio Operation
– Make before break as primary mode of operation
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802.21 - Industry Observations
 ND&S a big issue only for 802.11 networks
– Not such a big issue for other networks operating primarily
in licensed bands
– Inter-RAT Neighbor Advertisements are good enough
– Operators skeptical about dedicated IS server
 L3 MM Protocols are not widely deployed
– CMIP not that widely used
– PMIP may not require significant 802.21 services
 Network initiated HO are compelling
– Require significant investments
– Done in network specific manner
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Handovers – Key Issues
 Co-existence & Interference issues prevent dual
radio operation in many UEs
 Need optimized HO solutions for Single Radio
operation (one radio transmitting at a time ONLY…)
– May not be able to do Make operation before Break
– Need to transition to 3GPP from WiMAX during voice call
 Key 802 involved Handover Scenarios
– WiMAX <> 3GPP2/3GPP
– WiMAX <> WiFi
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Key Elements of Handover Functionality
Target Preparation is the Key aspect of Optimized Handovers
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Capability
Motivation
Complexity
Inter-RAT network
advertisements
Helps reduce power consumption on the device.
Required for single radio operation. The WiMAX
module will only turn on if WiMAX coverage is
available
Low
Inter-RAT Traffic
Anchoring
Eliminates L3 mobility signaling in inter-RAT
mobility by keeping L3 anchor in the previous
RAT access gateway. Requires inter-RAT
interface between access gateways
Low-Medium
Inter-RAT L2 Handoff
Optimization
Speeds up handoff procedure (e.g. passing
security keys). Requires inter-RAT interface
between access gateways
Medium
Inter-RAT NetworkInitiated Handoff
Enables operators to enforce handoff policies
and decisions. Requires inter-RAT measurement
reporting
High
WiMAX Reference Diagram
Visited NSP
R2
Home NSP
R2
R3
R1
SS/
MS
ASN
R5
CSN
CSN
R4
Another ASN
NAP
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ASP Network OR
Internet
ASP Network OR
Internet
WiMAX – R4
 Expected to get modified for Inter-Tech Handovers
 Support Handover Messages
– HO_Req
– HO_Rsp
– HO_Cnf
– Context_Transfer
– Bearer Path Setup
 802.21 HO Messages (HO Flows) should align with
those in WMF specs for WiMAX related HOs
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Generic Inter-RAT Interfaces
AG-RAT1
Common Core
RAG
Mobile Station
(MS)
WMF-R4
AG-RAT2
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HLR
HSS
Inter-RAT
Server
HA
AAA
Conclusions
 Providing a complete solution for WiFi<>WiMAX HOs may be
the best value add for 802.21 …..in near term
– May need to define few more N2N Handover messages
 3GPP has some reservations w.r.t IS servers but 3GPP has
accepted providing information about 802 networks over
3GPP RANs
 Single Radio HO solution is one of the Key Activity in 3GPP
– WiMAX<>3GPP/2
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BackUp
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SAE Architecture Enhancements for
WiMAX Optimized Handoff
GERAN
SGSN
UTRAN
S3
S1-MME
Sw1
MME
SGi
WiMAX IWF
“LTE-Uu”
UE
E-UTRAN
WiMAX-R1
S5
Serving
Gateway
X101
WiMAX
ASN
12
PDN
Gateway
S2a
SGi
Operator's IP Services
(e.g. IMS, PSS etc.)
Proposed Single-Radio HO Architecture
ASN GW
Mobile WiMAX
IP Access
X101
Non-3GPP
Networks
S2a
HPLMN
X1
FAF
Relay
FAF
S1MME
MME
S11
S3
S10
UE
Serving
GW
E-UTRAN
S1-U
GERAN /
UTRAN
Operator’s IP
services
SGSN
S5
PDN
GW
SGi
S4
X200





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X200 interface terminates to an FAF Relay
X200 based on L3 tunnel
X1: between FAF Relay and FAF/MME (both in the same network)
UE does NOT need to discover the FAF Relay in the HPLMN (can be provisioned)
X101: Used for 3GPP to mobile WiMAX pre-registration & for NW-initiated HO from
mobile WiMAX to 3GPP
3GPP to WiMAX
UE/
ME
Target
WiMAX ASN
Source 3GPP
Network
Source
SGSN
WiMAX
IWF/MME
Serving
GW
PDN GW
/HA
Uplink & Downlink PDUs (may traverse target SGSN)
1. WiMAX Radio on
2. Decision to perform HO to WiMAX
3. IKEv2 Auth & IPSec Setup
4. Handover Request
5. WiMAX R4 Handover Request
4a. WiMAX
DL Sync
6. WiMAX R4 Context Request
7. WiMAX R4 Context Response
8. WiMAX
Resource Preparation
9. Proxy Binding Update (PMIP)
10. Proxy Binding Ack (PMIP)
11. WiMAX R4 Handover Response
12. WiMAX R4 Handover Ack
13. Handover Command
14. WiMAX PHY/MAC
Establishment
Uplink & Downlink PDUs
15. Release 3GPP Resources
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3. Authentication & Authorization
HSS/A
AA
WiMAX to 3GPP
UE/
MS
WiMAX
ASN
Target 3GPP
Network
Target
SGSN
WiMAX
IWF/MME
Serving
GW
PDN GW
/HA
Uplink & Downlink PDUs
1. 3GPP Radio on
2. Decision to perform HO to 3GPP
3. IKEv2 Auth & IPSec Setup
3. Authentication & Authorization
4. Handover Request
5. WiMAX R4 Handover Request
6. Rest of 3GPP Attach with the target network
7. Forward
Relocation REQ
8. Target SGSN prepares
3GPP access network
9. Forward
Relocation RES
10. Create Default
Bearer REQ
11. PMIP Proxy BU/
GTP Create Bearer REQ
13. Create Default
Bearer RES
14. Handover Command
15. Handover Complete
Uplink & Downlink PDUs (may traverse target SGSN)
16. WiMAX R4 Handover Response
17. WiMAX R4 Handover Ack.
18. Release WiMAX Resources
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12. PMIP Proxy BA/
GTP Create Bearer RES
HSS/A
AA