The IP.com Journal (v8n8A)
Juergen Carstens - Contact
email@example.com; phone +49-89-636-82995
Nokia Siemens Networks 2008
English (United States)
5 pages / 133.3 KB
Architecture Alternatives for LTE Femto GW Integration into the Evolved Packet Core
Idea: Ivan Ore, FI-Espoo; Joanna Jokinen, FI- Espoo; Tom Grahn, FI- Espoo; Jarmo Virtanen, FI-
The LTE (Long Term Evolution) technology, which is currently under the standardization by 3rd
Generation Partnership Project (3GPP), will deliver ultra-broadband speeds and almost instantaneous
responsiveness for multimedia applications. To take full advantage of these broadband access
networks and to enable the co-existence of multiple technologies through an efficient, all-packet
architecture, 3GPP is developing a new core network, the evolved packet core (EPC). The current
EPC architecture is illustrated in Figure 1. The evolved packet system (EPS) comprises the EPC and a
set of access systems such as the eUTRAN or UTRAN (eUTRAN: evolved UMTS Terrestrial Radio
Access Network, UMTS: Universal Mobile Telecommunications System). EPS represents a migration
from the traditional hierarchical system architecture to a flattened architecture that minimizes the
number of hops and distributes the processing load across the network.
Furthermore, closed subscription groups (CSG) are introduced as a new concept in 3GPP cellular
networks where certain access nodes are restricted to a certain group of users. This restriction should
be taken into account in the UE (User's Equipment) mobility procedures in idle and dedicated mode.
The support of CSG adds requirements documented in TS 36.300 Annex F to UE, radio access
(eNodeB, HNB (HomeNodeB), etc) and the core network (EPC). Some of the CSG requirements
impacting the core network are:
1. Handling two kinds of multimedia identifiers (IDs): 1) Tracking area identifier and 2) CSG
network identifier. The CSG network identifier identifies the closed subscription group. A
collection of CSG network identifiers can be stored in UE memory on the whitelist. The UE
is only able to access the CSG networks that are registered in the UE whitelist. To support
a large number of CSG networks, for example home cells, the CSG network identifier may
be long (e.g. 30 bits).
2. Updates of the subscriber information (CSG membership class), which may be delivered
to eNodeB during the S1 establishment.
3. Updating in the NAS (Non-Access Stratum) signaling:
4. Mobility Management Entity (MME) informs the UE via NAS signaling whether the CSG
cell search can be done in the Tracking Area (TA).
5. Updating the CSG whitelist of the UEs (UE has to confirm the whitelist updating via NAS
signaling as well).
6. Handling the three lists: mobility, forbidden TAs and allowed CSG network IDs (whitelist).
7. Database for the mapping of the TA and the network ID (location).
8. Database for mapping CSG members and network ID.
9. The databases have to be updated in real time upon CSG owner request.
One of the most important CSG scenario...