1. 1 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

2. 2 IEEE 802.21 presentation release statements This document has been prepared to assist the IEEE 802.21 Working Group. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.21. The contributor is familiar with IEEE patent policy, as outlined in Section 6.3 of the IEEE-SA Standards Board Operations Manual and in Understanding Patent Issues During IEEE Standards Development http://standards.ieee.org/board/pat/guide.html> Section 6.3 of the IEEE-SA Standards Board Operations Manualhttp://standards.ieee.org/guides/opman/sect6.html#6.3 http://standards.ieee.org/board/pat/guide.html

3. 3 802.21 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

4. 4 802.21 - 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

5. 5 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

6. 6 Key Elements of Handover Functionality CapabilityMotivationComplexity 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 Network- Initiated Handoff Enables operators to enforce handoff policies and decisions. Requires inter-RAT measurement reporting High Target Preparation is the Key aspect of Optimized Handovers

7. 7 WiMAX Reference Diagram

8. 8 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

9. 9 Generic Inter-RAT Interfaces Mobile Station (MS) AG-RAT1 AG-RAT2 R AG Common Core HA AAA HSS HLR R core Inter-RAT Server RSRS RSRS 802.21 WMF-R 4

10. 10 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

11. 11 BackUp

12. 12 SAE Architecture Enhancements for WiMAX Optimized Handoff WiMAX ASN WiMAX-R1 SGi S3 S1-MME UE GERAN UTRAN SGSN LTE - Uu E-UTRAN MME S5 Serving Gateway PDN Gateway Operator's IP Services (e.g. IMS, PSS etc.) S2a WiMAX IWF X 101 Sw1 SGi

13. 13 Proposed Single-Radio HO Architecture 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 PDN GW S1- MME S10 MME S11 UE E-UTRAN SGi S1-U S2a X101 ASN GW Serving GW S5 SGSN GERAN / UTRAN S3 FAF X200 S4 Mobile WiMAX IP Access HPLMN Non-3GPP Networks FAF Relay Operators IP services X1

14. 14 3GPP to WiMAX UE/ ME Target WiMAX ASN Source 3GPP Network Source SGSN WiMAX IWF/MME Serving GW HSS/A AA 4a. WiMAX DL Sync 15. Release 3GPP Resources Uplink & Downlink PDUs (may traverse target SGSN) 5. WiMAX R4 Handover Request 3. IKEv2 Auth & IPSec Setup3. Authentication & Authorization 6. WiMAX R4 Context Request 7. WiMAX R4 Context Response 9. Proxy Binding Update (PMIP) 10. Proxy Binding Ack (PMIP) 2. Decision to perform HO to WiMAX 4. Handover Request PDN GW /HA 14. WiMAX PHY/MAC Establishment 1. WiMAX Radio on 13. Handover Command Uplink & Downlink PDUs 8. WiMAX Resource Preparation 11. WiMAX R4 Handover Response 12. WiMAX R4 Handover Ack

15. 15 WiMAX to 3GPP UE/ MS WiMAX ASN Target 3GPP Network Target SGSN WiMAX IWF/MME Serving GW PDN GW /HA HSS/A AA 2. Decision to perform HO to 3GPP 3. IKEv2 Auth & IPSec Setup 3. Authentication & Authorization 1. 3GPP Radio on Uplink & Downlink PDUs 7. Forward Relocation REQ 9. Forward Relocation RES 6. Rest of 3GPP Attach with the target network 15. Handover Complete 18. Release WiMAX Resources 14. Handover Command 11. PMIP Proxy BU/ GTP Create Bearer REQ 13. Create Default Bearer RES Uplink & Downlink PDUs (may traverse target SGSN) 4. Handover Request 10. Create Default Bearer REQ 12. PMIP Proxy BA/ GTP Create Bearer RES 8. Target SGSN prepares 3GPP access network 5. WiMAX R4 Handover Request 16. WiMAX R4 Handover Response 17. WiMAX R4 Handover Ack.