On Supporting IP Routing in the Next Generation of Mobile Systems

The upcoming generation of mobile telecommunication systems is expected to support new use cases, where the mobile network serves one or more IP subnetworks located behind the User Equipment (UEs). This would create new challenges for the mobile system to efficiently serve such behind-UE subnetworks, as the latter are commonly not visible to the mobile system. In 3GPP, there have been works on Time-Sensitive Networking (TSN) and Deterministic Networking (DetNet), where the 5G System (5GS) is considered as a bridge or a DetNet node. In order to efficiently serve behind-UE IP subnetworks, we foresee the need for a further generalization where the mobile system (5GS and beyond) acts as a set of IP routers with more generic capabilities. In this article, we introduce the concept of Mobile System Router (MS-Router) which aims to provide a reference architectural design to enable the support of IP routing in the next generation of mobile telecommunication systems. The concept models a mobile system as an IP router per User Plane granularity. Each MS-Router implements an IP routing protocol, exchanges routing messages with the external routers and constructs a routing table, enabling the mobile system to dynamically learn the topology of the IP subnetwork behind the UEs and Data Network. The learned topology is translated into User Plane configuration to serve the IP subnetworks in an optimal way. The article also advocates different approaches where routing protocols can be implemented in the mobile system.