1. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 1 WLAN – Cellular Interworking Stephen McCann, Siemens Roke Manor stephen.mccann@roke.co.uk

2. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 2 Who am I? I work for Siemens in the UK. I don’t represent ETSI, MMAC or any working group within it, nor does this presentation However, this is an attempt to be a non- partisan overview of previous interworking activities in ETSI, MMAC and IEEE 802.11

3. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 3 Coupling Approaches Loosely, classify against two extremes: –Re-use WLAN radio layer within existing public network –Deploy public network services on WLAN network The ‘tight’ approaches are more specific, complex, functional –(and disruptive to existing standards) The ‘loose’ approaches don’t rule out operators falling into the more specific categories Also, alternative directions for other mobile standards (CDMA etc.)

4. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 4 Previous work

5. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 5 WLAN Standardisation } WIG

6. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 6 IEEE 802.11 & WIG Plenary Motion Approved in 2002Plenary Motion Approved in 2002 –Move that the WNG Standing Committee requests the 802.11 WG to accept the invitation from ETSI-BRAN and MMAC to participate in the “WLAN – 3G and other Public Access networks “interworking” (WIG) project.

7. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 7 What was WIG all about ? To establish a joint-effort between 802.11 and ETSI BRAN/MMAC HSWA for the interworking of WLANs to 3G Cellular systems. 802.11 should be represented by its own interworking group.

8. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 8 Previous work At engineering level, TGi already has similar approach to external authentication (EAPoL) to that of other WLAN standards (e.g. Hiperlan & HiSWAN) Previous interworking activities done by ETSI BRAN and MMAC HSWA have similar approach to that of 802.1x

9. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 9 WIG Intended Output ? WIG Baseline Document Common text, which will then be passed based to recognised WLAN standards bodies (ETSI, IEEE & MMAC) for their regulatory approval. WIG cannot NOT approve final output

10. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 10 Why bother ? To create a world wide standard for WLAN interworking with Cellular and Public Access networks. To encourage the proliferation of world wide WLAN hotspots, regardless of local regulatory constraints.

11. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 11 IEEE 802.11 activities Necessity to align interworking work from TGe, TGi, WNG and 802.1 Procedural requirement to establish some kind of interworking group within 802.11 to address these issues.

12. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 12 IEEE 802.11 Interworking No specific group in IEEE802.11 dedicated to interworking issues Many external activities in this area, 3GPP, 3GPP2, GSMA, WiFi Alliance all addressing interworking issues. Bits of interworking done in WNG, TGi, TGe, 802.1 (802.1x and 802.1aa)

13. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 13 IEEE 802.11 Interworking Study Group Proposed Scope The scope of the study group is to consider whether there is a requirement to enhance the IEEE 802.11 standard (and amendments), to add interworking capability to both cellular and external IP based networks. The intention is to re-use the output of existing Task Groups to form a complete interworking solution, and to fill in any gaps.

14. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 14 Coupling

15. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 15 Traditional Coupling Models Loose Coupling –Avoids use of core network gateways (e.g. SSGN) –Applicable to many 2.5G, 3G systems Tight Coupling –WLAN is an alternative UTRAN –Specific to particular network technology Hybrid – bit of both

16. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 16 Control Plane Interworking Defines a ‘control plane only’ convergence layer Handles primarily AAA issues –Can authenticate using SIM or other identifier –Focus is on security and roaming support –Intra-network mobility and QoS are handled in ‘user plane’

17. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 17 Architecture

18. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 18 Control & User Plane Interworking WLAN becomes a ‘peer’ RAN to UTRAN –Similar status to GERAN for GSM/GPRS –Re-use many UMTS functions as is (e.g. idle mode?) Covers the complete security/mobility/QoS problem, using UTRA-like internal model Retains 3GPP Iu interface, mainly unmodified Whole family of new WLAN related interfaces –IurWLAN, IubWLAN – network internal –UuWLAN – extensions or changes to air interface protocols (mainly in RLC layer)

19. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 19 Architecture Similar interface methodology to UTRAN Can extend to very seamless UTRA-WLAN handover (dual mode terminals)

20. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 20 Implications Strong dependencies on what mobile network considered –Even on UMTS release number (R5, R6) Strong dependencies on WLAN technology Simpler AN functionality – Core does much more of the work Significantly greater impact on WLAN and non- WLAN standards (apparently) –Re-engineering of one to fit into the assumptions of the other

21. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 21 Architecture detail

22. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 22 Interworking architecture

23. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 23 802.11 Phy 802.11 MAC 802.1x/EAPoL EAP EAP Method 802.11 Phy 802.11 MAC 802.1x/EAPoL EAP Radius IETF Transport EAP EAP Method Radius IETF Transport Service providers net AP MT WLAN AN HL2/HiSWANa 802.11i GST/EAPoH EAP EAP Method GST/EAPoH EAP Diameter IETF Transport EAP EAP Method Diameter IETF Transport Phy DLC/RLC Phy

24. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 24 Security Issues Working assumption to use EAP Method for transport of EAP over air is defined Support for SIM/USIM authentication required by 2G/3G operators –But also required that this is not the only mechanism –AKA extension (i-d) for mapping 2G/3G messages to EAP

25. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 25 Accounting and Charging System level requirements : –Basic access/session (pay by subscription) –Access/session duration –Credit card access/session/ Not real time pre paid –Calendar and time related charging –Duration dependent charging –Flat rate –Volume of transferred packet traffic –Multiple rate charge Useful features –Rate of transferred packet traffic (Vol/sec). –Toll free (like a 0800 call) –Premium rate access/session –Real time Pre-paid

26. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 26 Inter-System Handover Issues Inter-system handover is a very hard problem –Weakly supported in loose coupling case Basically network reselection by terminal Terminal has to accept that it will get a new IP address with implications for session continuity –Possible in tight coupling case but very hard IurWLAN very complex and interacts strongly with existing equipment Main gain comes from joint management of the radio resource (but main pain also) –MobileIP is always a fall-back (and near-transparent) –Affects only multi-mode terminals anyway –Need in public environment needs to be examined

27. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 27 Quality of Service If anything, can be even more complex than security and mobility Loose coupling approach leaves most options open (TGe etc) Tight coupling leverages UMTS QoS architecture Need to distinguish carefully: –What the operator wants to do –What the user wants to do –What the user’s applications are capable of doing

28. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 28 Way Forward 802 Handoff produces generic solution to homogeneous and heterogeneous interworking. 802.11 Interworking group (?) studies specific problems related to Cellular interworking.

29. IEEE P802 Handoff ECSG Submission November 2003 Stephen McCann, Siemens Roke ManorSlide 29