TS%2023.402**):%20Non-Roaming%20Reference%20Architecture%20for%20non-3GPP%20Accesses

1
TS 23.402) Non-Roaming Reference Architecture
for non-3GPP Accesses
HSS
Wx
) Colouring of non-3GPP accesses and red arrows
(incl. text in red) added for this presentation
S6a
S4
2G/3G SGSN
PCRF
S3
Rx
S7
MME
S11
Operators IP Services (e.g. IMS, PSS etc.)
SGi
S1-MME
Serving SAE Gateway
PDN SAE Gateway
S10
EUTRAN
S5
S1-U
S6c
S2b
Wm
3GPP AAA Server
ePDG
S2a
S2c
Wn
HPLMN
Non-3GPP Networks
Trusted Non-3GPP IP Access
Untrusted Non-3GPP IP Access
Trusted/Untrusted Non-3GPP IP Access or 3GPP
Access
Wa
Ta
UE
Untrusted non-3GPP access requires ePDG in the
data path
Handovers (Discovery and Selection of non-3GPP
Access is needed before)
2
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.

3
Example of HO Message Flow (from informative
annex of TS 23.402)
Untrusted non-3GPP IP Access
2. UE discovers the untrusted non-3GPP access
system and initiates HO