nascTime: A Full-Stack 5G-TSN Bridge Simulation Framework with SDAP-Based QoS Mapping and IEEE 802.1AS Transparent Clock
Mohamed Seliem, Utz Roedig, Cormac Sreenan, Dirk Pesch
Abstract
The integration of 5G with IEEE 802.1 Time-Sensitive Networking (TSN) is essential for enabling flexible and mobile deterministic communication in industrial automation. The 3GPP Release 16 specification defines a bridge architecture where the 5G system operates as a transparent TSN bridge, incorporating Network-side and Device-side TSN Translators (NW-TT, DS-TT), a TSN Application Function, and QoS mapping between TSN Priority Code Points and 5G QoS Flow Identifiers. However, existing simulation frameworks model only subsets of this architecture, either QoS mapping without time synchronization, or time synchronization without data plane traffic, and none implements the complete QoS pipeline through the 3GPP SDAP layer with per-flow Data Radio Bearer selection. We present nascTime[20], an open simulation framework built on OMNeT 6.3, INET 4.6, and Simu5G that implements the complete 3GPP Release 16 5G-TSN bridge model. The framework provides end-to-end QoS mapping from TSN PCP through to 5G QFI via the SDAP/DRB pipeline, IEEE 802.1AS transparent clock behavior with measured residence time correction through L2-in-GTP-U gPTP transport, and multi-endpoint scaling with bidirectional traffic. The bridge ports integrate with INET's LayeredEthernetInterface and streaming PHY for compatibility with TSN features including Time-Aware Shaping and frame preemption. We validate nascTime with a three-endpoint factory scenario demonstrating near-perfect packet delivery across two traffic classes, correct gPTP synchronization with residence time correction, and zero packet loss. nascTime is the first simulation framework to model the full 5G-TSN bridge data path with SDAP-based QoS differentiation and measured IEEE 802.1AS transparent clock behavior in a multi-endpoint topology.