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Trusted Non-3GPP IP Access

TS 23.402**): Non-Roaming Reference Architecture for non-3GPP Accesses

Trusted/Untrusted* Non-3GPP IP

Access or 3GPP Access

SGi

PCRF

S7

S6a

HSS

ePDG

S2b

Serving SAE

Gateway

Wn*

3GPP AAA Server

Operator’s IP Services

(e.g. IMS, PSS etc.)

Wm*

Wx*

UntrustedNon-3GPP IP Access

Wa*

Ta*

HPLMN

Non-3GPP Networks

S1-U

S1-MME

EUTRAN

2G/3G SGSN

S4

S3

S5S6c

Rx+

S2a

PDN SAE

Gateway

MME S11

S10

UE

S2c

* Untrusted non-3GPP access requires ePDG in the data path

Handovers (Discovery and Selection of non-3GPP Access is needed before)

**) Colouring of non-3GPP accesses and red arrows (incl. text in red) added for this presentation

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Key Issue NW Discovery & Selection (NW-DS)(Excerpt from TR 23.882)

It is necessary to optimize NW-DS procedures for frequent mobility events.

It is desirable that the concept for NW-DS in SAE supports effective means for minimizing processing.

Looking at the currently defined NW-DS principles for I-WLAN in TS 23.234 it becomes clear that they cannot be extended for time critical handovers and for other RATs, due to complexity and latency:

per available WLAN access NW a scan/probe has to be performed if a WLAN AN is connected to more than one 3GPP NW this is only detected after L2 association and trying authentication.

It is therefore necessary to develop or adopt new, more efficient mechanisms, for both idle and active mode (where this differentiation is applicable).

Solutions may be based on concepts developed in other fora (e.g. IEEE 802.11u, IEEE 802.21, IETF) or based on concepts defined by 3GPP (e.g. provision of specific databases). Further mechanisms are FFS. When selecting solutions, the amount of signalling, size of stored and transferred data, especially over the radio interface, and terminal power consumption shall be taken into account.

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Example of HO Message Flow (from informative annex of TS 23.402)

Ipsec Tunnel

ePDGMME-EUTRAN

Untrusted Non-3GPPIP Access

UE

2. UE discovers the untrusted non-3GPP access system and

initiates HO

PDNGW

HSS/AAA

7. BU/BA (IP Addr)

PCRFServing GW

1. GTP/PMIPv6 Tunnel

3. Access Authentication

8. DSMIPv6 Tunnel

3. Access Auth

6. IKEv2/Ipsec SA setup6. AAA Auth/

Authz

5. IKEv2/Ipsec SA setup (CoA config) 5. AAA Auth/ Authz

4. ePDG Discovery

Untrustednon-3GPP IP Access

2. UE discovers the untrusted non-3GPP access system and

initiates HO