The UDR is a functional entity that acts as a single logical repository storing user data. The user-related data
traditionally stored in the HSS/HLR/AuC, Application Servers, etc., are now stored in the UDR. UDR facilitates the
share and provisioning of user-related data. The UDR provides a unique reference point to Application Front Ends such as HSS/HLR/AuC/AS Front Ends. This reference point is named Ud. More information on the UDR can be found in
The UE allows a user access to network services. For the purpose of 3GPP specifications the interface
between the UE and the network is the radio interface. A UE can be subdivided into a number of domains, the domains being separated by reference points. Currently the User Equipment is subdivided into the UICC domain and the ME Domain. The ME Domain can further be subdivided into one or more Mobile Termination (MT) and
Terminal Equipment (TE) components showing the connectivity between multiple functional groups.
The SIM IC card that originated with GSM has evolved from Rel-3 towards the UICC (Universal Integrated Circuit Card). While for the SIM, the card platform and the Telecom application were specified in common by the 3GPP CT6, with the UICC the platform and the applications are specified separately. The UICC is the platform defined by the ETSI SCP (Smart Card Platform) and the 3GPP applications are specified by the 3GPP CT6, especially the USIM.
Trusted and Untrusted Non-3GPP Access Networks are IP access networks that use access technology whose
specification is out of the scope of 3GPP.
Whether a Non-3GPP IP access network is Trusted or Untrusted is not a characteristic of the access network.
In non-roaming scenario it is the HPLMN's operator decision if a Non-3GPP IP access network is used as Trusted or
Untrusted Non-3GPP Access Network.
In roaming scenario, the HSS/3GPP AAA Server in HPLMN makes the final decision of whether a Non-3GPP IP
access network is used as Trusted or Untrusted non-3GPP Access Network. The HSS/3GPP AAA Server may take the
VPLMN's policy and capability returned from the 3GPP AAA Proxy or roaming agreement into account.
For supporting multiple PDNs, the same trust relationship shall apply to all the PDNs the UE connects to from a certain
Non-3GPP Access Network, i.e. it shall not be possible to access one PDN using the non-3GPP access network as
Trusted, while access to another PDN using the same non-3GPP access network as Untrusted.
Main application residing on the UICC, besides other applications such as the ISIM. From R3, it has replaced the application part of the SIM and has been enhanced gradually for supporting the new release features. It is detailed in 3GPP (CT6) TS 31.102
The UTRAN consists of a set of Radio Network Subsystems connected to the Core Network through the Iu.
A RNS consists of a Radio Network Controller, one or more Node Bs, and optionally one SAS. A Node B is connected
to the RNC through the Iub interface.
Inside the UTRAN, the RNCs of the Radio Network Subsystems can be interconnected together through the Iur. Iu(s)
and Iur are logical interfaces. Iur can be conveyed over direct physical connection between RNCs or virtual networks
using any suitable transport network.