Joint Scheduling of IEEE 802.1AS gPTP and Industrial Data Traffic in TSN-6G Networks

Abstract

The 6th Generation (6G) mobile network is envisaged to play a significant role for supporting time-sensitive applications in industrial scenarios. The integration between 6G and (wired) Ethernet Time-Sensitive Networking (TSN) is a natural step to provide end-to-end deterministic communications guaranteeing bounded latency. Time synchronization, which is key for the operation of industrial automation networks, can be provided via the IEEE 802.1AS generalized Precision Time Protocol (gPTP). This protocol is executed over the integrated TSN-6G network to synchronize industrial devices and to keep the TSN bridges synchronized to support the IEEE 802.1Qbv Time-Aware Shaper (TAS). The TAS is a time-triggered scheduling mechanism commonly used to guarantee the delay requirements of industrial data traffic. The gPTP traffic may also be scheduled as a critical traffic, requiring careful consideration. First, the accuracy provided by gPTP relies on the effective transmission of the gPTP packets over the integrated TSN-6G network. Second, uncoordinated or misaligned TAS schedules in the TSN bridges due to loss of timing accuracy may provoke undesired packet delays. Third, the 6G system may introduce additional sources of timing inaccuracies with respect to a TSN-native network. In this paper, we propose a TAS-based scheduling scheme for gPTP traffic and industrial data traffic by allocating them a number of periodic, aligned time intervals, such that the provided timing accuracy and schedules are enough to transmit the time-critical packets in the specified time intervals. We compare by simulation various configurations for comprehensive analysis of synchronization accuracy, end-to-end delay and bandwidth utilization.