1 / 23

Improved LTE mobility mgmt

Improved LTE mobility mgmt. Buu -Minh Ta Charlie Perkins. Constraints & Goals. Constraints. Goals. eNodeB and MME shouldn’t be changed Use existing LTE authentication procedures Use existing policy interface via HA. Smooth and quick handovers

analu
Télécharger la présentation

Improved LTE mobility mgmt

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Improved LTE mobility mgmt Buu-Minh Ta Charlie Perkins

  2. Constraints & Goals Constraints Goals • eNodeB and MME shouldn’t be changed • Use existing LTE authentication procedures • Use existing policy interface via HA • Smooth and quick handovers • Identify Mobile IP features needed to support inferred LTE design goals • Present at IETF, publish

  3. Issues • S-GW • What is its purpose? • Only intermediary on the GTP tunnel • Handovers between other networks? • Length of procedures… • How many roundtrips to establish the connection?

  4. Initially planned response • Observation: Past projects have exhibited excellent performance using Mobile IP. • [S-GW + P-GW] = P-GW/S-GW  HA-D • pMME (proxy MME) HA-C • Keep existing PCEF/PCRF/PCC • Keep existing MME authentication

  5. Why is S-GW separate from P-GW? • It’s not all that easy to figure out • Some purported justifications: • Aggregation of mobility events • Distribution of statistics gathering • Hiding aspects of radio technology • Enabling multi-homed eNodeBs • By now, the P-GW and S-GW seem tightly bound • A fully routed EPC seems likely to work “better”

  6. Overall Architecture

  7. Architecture (1)Internal HA HA-D S-GW/P-GW P-GW P-GW GTP MME MME GTP HA-C pMME S-GW S-GW GTP eNodeB eNodeB UE UE

  8. Architecture (1)Internal HA

  9. Architecture (2)External HA

  10. Modifying Mobile IPv6 • Split HA into HA-D (== P-GW) + HA-C (== MME) • Enable HA to tunnel via GTP • HA-C  HA-D via GTP-C • Enable alternate security association (algorithm, data) • Enable Binding Authorization for HA • Enable alternative CoA • Problem: UE has no unique ID for eNodeB

  11. Procedures

  12. Moving to a network using MobileIP • Initial Attach • ..\Initial Attach.vsd • Initial Attach with external HA • ..\Initial Attach - HA external.vsd

  13. Extensions to NAS protocol and Mobile IPv6

  14. New NAS Attach Request message (UEpMME, pre-existing HA) • Attach Request: current message sent by UE to MME (protected using EPS security association). Encapsulated into a NAS container IE. • Ciphered Options: avoid one round trip to the UE. • Identifier: NAI. • HA address: so the pMME can send the BU. • Derived Key: to establish a security association between pMME and HA. • Ciphered derived key: so the HA can know the derived key, and verify it has been establish by the UE.

  15. New NAS Attach Request message (UEpMME, non-existing HA) Attach Request: current message sent by UE to MME (protected using EPS security association). Encapsulated into a NAS container IE. Identifier: NAI. Ciphered Options: avoid one round trip to the UE.

  16. Binding Update (pMMEP-GW)External HA Care-of Address: external address of the P-GW. Binding Authorization Data: signature on everything that precedes, using the derived key. Create Session Request: extracted by the P-GW. Ciphered Key: same as in the Attach Request.

  17. Binding Update (pMMEP-GW)Internal HA TEID: eNodeB GTP Tunnel Enpoint.

  18. Pre-Authentication with LTE network • Context: • UE is within reach of LTE network, but has not initiated attach and handover. • Goals: • Pre-authentication with pMME and MME to establish security association. • “Pro-active handover” to make the handover quicker.

  19. Pre-Authentication with LTE network • How can we do it? • Pre-Authentication Request containing Attach Request to pMME. • pMME fakes the attach of the UE to a “virtual” eNodeB by forwarding the Attach Request to the MME. • Current Authentication and Identification procedures. • Pre-create the session within the P-GW • When the UE initiates the attach: • Continues the procedure (session already created, P-GW TEID available): Attach Accept • Basically, just need the eNodeB TEID to establish the tunnel.

  20. Pre-Authentication signal flow • Pre-Authentication • ..\Pre-Attach + Attach - HA external.vsd

  21. Additional steps • Consider client-triggered PMIP approach. • Map signaling to multi-stage HA into HMIP approach. • Insert preregistration sequences from SFF designs, attempt the application of FMIP context transfer.

  22. Is it better? • With so many modifications, one wonders whether it is worth it to use Mobile IPv6 • But – compared to existing procedures, it is still much simpler – less signaling, fewer steps • Most of the complexity is due to constraint to avoid modifications to eNodeB/MME/GTP etc. • Have an almost complete spreadsheet

  23. Next Steps • Build it • Experiment with new signaling designs • Try with simulators • Measure performance • Submit documents to [mext], [netext] • Submit documents to 3GPP SA2 • Wait for hell to freeze over

More Related