A 3-Dimensional Broadcast Protocol with Optimized Transmission Efficiency in Industrial Wireless Networks

Wireless technologies are promising for industrial automation and distributed control due to the properties of mobility, reduced deployment and maintenance costs, and so on. By the technologies, wireless networks are formed for integrating processes and devices of industrial systems. Broadcasting is one of the most important operations in the wireless network for disseminating information throughout the entire network. Flooding is a simple mechanism to realize broadcasting, but it has high redundancy of retransmissions, leading to low transmission efficiency. Many broadcast protocols have been proposed for pursuing optimized transmission efficiency for wireless networks hypothetically deployed on the 2-dimesional (2D) plane. In some industrial applications (e.g., a multi-storey factory), however, wireless networks are deployed in the 3D space. In this paper, we derive the upper bound of 3D transmission efficiency and propose a 3D broadcast protocol, called 3DOBP (3-Diemsional Optimized Broadcast Protocol), to achieve optimized transmission efficiency by partitioning the 3D space into multi-layer hexagonal prisms of a hexagon ring pattern in each layer. As we will show, the transmission efficiency of the proposed protocol is 1/π, which is better than those of polyhedron-filling 3D broadcasting approaches using cubes, hexagon prisms, rhombic dodecahedrons, and truncated octahedrons. To the best our knowledge, the proposed broadcast protocol is the one with the highest 3D transmission efficiency so far.