Introducing multi-level communication in the IEEE 802.15.4e protocol: The MultiChannel-LLDN

The Low Latency Deterministic Network (LLDN) protocol is defined in the IEEE 802.15.4e, which is an amendment to the IEEE 802.15.4 standard specifically devised to support the requirements of industrial applications. The LLDN provides a TDMA-based medium access mechanism in which the network cycle time grows linearly with the number of nodes. As a result, to offer low cycle times to applications requiring a high number of nodes, the LLDN specifications suggest to create multiple networks operating on different channels by embedding multiple transceivers in the coordinator. However, such an approach entails high costs and increases the design complexity. Moreover, the LLDN protocol foresees a star topology that limits the network area coverage. This paper proposes a novel approach, called a MultiChannel LLDN, based on a hierarchical network structure in which nodes communicate on different channels at the same time. The approach supports a high number of network nodes while maintaining short cycle times without the need for multiple transceivers in the coordinator and also provides backward compatibility with the standard LLDN. The paper presents the MultiChannel LLDN and comparative performance assessments.