Core Network Support for Other 3GPP Accesses

OpenEPC includes the core network functionality related to other 3GPP accesses than LTE such as HSPA+, HSPA, UMTS, EDGE and GPRS. The LTE related functionality is available here. The core network support for the 3GPP accesses consists of an SGSN implementation and a NodeB simulation which emulates the specific characteristics through a generic RAN over WiFi technology. The functionality for the SGSN integration into the EPC follows the requirements from the EPC from 3GPP TS 23.401 as well as the adaptation required through the usage of the former core network for the 3GPP accesses from 3GPP TS 23.060. Similarly to the core network support for the LTE access, the components of the support for the other 3GPP acceses enables the showcasing of specific connectivity features for various service platforms and applications as well as it represents a major step towards the integration of off-the-shelf available radio technology specific hardware for licensed spectrum communication.

The implementation includes the S4 reference point between the SGSN and S-GW enabling the signaling of the connectivity procedures towards the EPC using the OpenEPC stack as specified in 3GPP TS 29.274. Additionally, the S12 reference point is implementing including the encapsulation and transmission of data packets between the S-GW and a RAN access stub, generically named in the implementation NodeB using the GTP encapsulation mechanisms. Additionally, the SGSN is equipped with the S6d reference point enabling the authentication and authorization of the subscribers as described in 3GPP TS 29.272. For the signaling between the RAN and the SGSN a generic GTP-C interface was deployed enabling the exchange of authentication and authorization information for the establishment and termination of the connectivity of the specific devices.

As the functionality of OpenEPC Rel. 3 regarding the 3GPP accesses other than LTE implements a great majority of the required features, an aggressive timeline was established for the integration of commercially available femtocells with the goal of enabling cost efficient radio and core network testbed setups. For the availability of specific access integration, please send us an email at info [at] openepc [dot] net.

web-epc-3gpp

The OpenEPC Core Network Support for other 3GPP accesses than LTE Access includes the functionality for the attachment and the detachment of UEs from the 3GPP access correspondent to the generic NodeB emulation. An aggressive timeline is considered for the development of the other features addressing the integration of real 3GPP access components as well as for the intra-3GPP handover support.

SGSN features:

New interfaces for interconnection with SGW (S4) and HSS (S6b)
Support for attachment and detachment procedures (based on the procedures from 3GPP TS 23.401 Section 5.3.2.1 and Section 5.3.8.2)
Support for default bearer establishment, modification and termination (based on the procedures from 3GPP TS 23.401 Section 5.3.2.1
Support for dedicated bearer with PCRF initiation procedures
Support for the security association through S6d reference point
Dual IPv4/IPv6 supported for GTP signaling
Context state saved in persistent MySQL database
Web based data base provisioning

SGSN features to be implemented on demand:

IDLE mode management
UE Reachability in ECM-IDLE state (including control and execution of paging retransmission);
Routing Area support;
Roaming (S6d towards home HSS);
Lawful Interception of signaling traffic;
No procedures GTPv1 to GGSN (no Gn/Gp interface)
No MME handover (S3 interface)

RAN emulation features:

support for default bearer establishment
support for the security association through the SGSN through S6d reference point
communication with the Fraunhofer FOKUS eDHCP serving IPv4/IPv6 addresses
dual IPv4/IPv6 supported for GTP signaling
ability to use various types of tunnels (ipip RFC2003, sit RFC4213, ipip6 RFC 2473, ip6ip6 RFC 2473), covering all possible IPv4/IPv6 connectivity combinations
context state saved in persistent MySQL database
Web based data base provisioning

RAN Limitations:

Radio technology functionality is not in the scope of the OpenEPC toolkit including header compression, bearer enforcement and admission control over the radio link. Integration with cost efficient off-the-shelf hardware will follow shortly.

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