Safe Clock Synchronization Mechanism for Multi-Cluster TTEthernet Networks

Abstract

The rapid progress in the area of The Internet-of-Things (IoT) promises a new generation of systems and system-of-systems(SoS). Multi-cluster systems with real-time communication networks are gaining increasing importance to meet the communication needs of SoS. To guarantee the required Quality of Service (QoS), SAE AS6802 specified a distributed clock synchronization method for the intra-cluster domain of Time-Triggered Ethernet (TTEthernet) and master-slave paradigm for the inter-cluster domain of multi-cluster TTEthernet. But the detailed clock synchronization operations for the multi-cluster TTEthernet are not presented. This paper proposes a safe clock synchronization mechanism for multi-cluster TTEthernet Networks. The proposed inter-cluster synchronization mechanism is executed to establish a global time base and not disturb clock synchronization mechanism of the intra-cluster domain. Besides, in consideration of the uncertainties derived from the accumulated jitter of time-triggered traffic, a fixed offset is introduced to guarantee a safe inter-cluster time-triggered communication. Moreover, the worst-case precision of the clock synchronization for multi-cluster TTEthernet networks is analyzed and validated by Symbolic Analysis Laboratory(SAL).