LTE roaming with the YateUCNTM in the home network
The YateUCN is a unified 4G LTE core network server performing the functions of the MME (Mobility Management Entity)/S-GW (Serving Gateway)/P-GW (Packet Data Network Gateway)/PCEF (Policy and Charging Enforcement Function). This allows it to be used in any type of roaming interconnect scenario preferred by the operator.
The software-defined YateUCN implements all the protocols in the EPC and for interworking with legacy networks, including Diameter and SS7 for the HSS/HLR and the charging function. This enables 4G devices to authenticate to foreign partners over SS7 roaming agreements, to an HLR. Devices can be registered to a GSM/GPRS network and an LTE network at the same time, if necessary.
For roaming, the YateUCN uses both Camel/MAP and Diameter.
When deployed in the home network, the YateUCN replaces the P-GW and the PCEF and establishes the IP session. It supports the S8 interface to connect to the visited S-GW and performs signalling and IP traffic, enabling the subscriber access to both the Internet or the IMS network.
In a visited network, the YateUCN performs the functions of the S-GW and MME. As an S-GW, the YateUCN enables signalling and IP traffic over the S8 interface, to the home P-GW. It also supports the S6a interface to connect to the home HSS.
Local IP breakout can be provided from YateUCN.
LTE roaming in conventional networks
Camel protocol for prepaid services is not supported in LTE. This makes prepaid subscriber data be handled in the home network instead of the visited network.
Operators who want to do roaming over LTE need a new infrastructure and new roaming agreements for Diameter.
To provide voice service with circuit-switched fallback (CSFB), operators need to align their networks with the standards and interfaces of their partners’ networks.
Transition to Voice over LTE requires a new infrastructure, as well as new agreements with partner operators.