Until Rakuten Mobile extends its new 4G/5G network across the whole of Japan, it is reliant on a roaming deal with larger Japanese MNO KDDI to fill the gaps. Users will not get the same low Rakuten tariffs when they move onto the KDDI system, but they will be able to get national coverage, including on the high speed trains.
Roaming between the two networks will be enabled by Cisco, which is providing an inter-network service based on the 3GPP’s S10 signaling interface standard. Cisco is running that interface within its Virtual Ultra Packet Core platform to connect the mobility management entities (MMEs) in Rakuten’s and KDDI’s networks, respectively. The MMEs track user data sessions to support handover.
The data path will be managed by connecting KDDI’s network with another element of the Cisco core, the virtualized System Architecture Evolution Gateway (SAEGW). This supports control/user plane separation, which allows MNOs to keep the control plane in the centralized location while moving the user plane closer to the applications.
Rakuten and KDDI are already linked through the 3GPP-based S8 interface, which is used for connecting the SAEGW virtual network functions in the core network and for transferring user data.
Kishen Mangat, head of Cisco’s Service Provider Mobility Business, said Rakuten was “using the S10 integration with KDDI’s network to provide a true production-grade service. That’s really the significance of this announcement, the realization of a macro-scale network given all the assets that are required with Rakuten’s architecture to make that happen.”
Cisco also has been working with KDDI on a proof-of-concept (PoC) that demonstrated cloud-native software with Cisco’s Ultra Packet Core, the goal being that “their 4G and 5G networks can reside on a common platform and interact seamlessly”.
“With the launch of our S10 roaming service, we are setting a new experience standard for service and device continuity over multiple networks,” said Tareq Amin, CTO of Rakuten Mobile.