## 1 Introduction  
Prefabricated buildings, as one practice of designed building components being made in factories in advance and then transported to the construction site for assembly, have been widely promoted across the world as one of sustainable construction methods for their advantages of a short construction period on-site, high quality, low cost and less energy consumption [1; 2]. It has also been reported that the global prefabricated buildings market was USD 159 billion in 2017, a substantial increase of more than 20% from the previous year [3], and which is expected to grow at a CAGR (Compound Annual Growth Rate) of over 8% during the period 2019-2025 [4]. Moreover, it is anticipated that the area of prefabricated buildings in China will be more than 200 million square meters every year after 2020 [5]. However, with the popularization and application of prefabricated buildings in practice, it is increasingly found that the low degree of information in the construction industry chain is one of the prominent problems impeding the application efficiency of prefabrication [6; 7]. Although some efforts have been made to facilitate information exchange through various emerging technologies (e.g., building information model (BIM) [8; 9], radio frequency identification technology (RFID) [10; 11],the global positioning system (GPS) [12]), the integration, interaction and collaboration of the upstream and downstream enterprises in the industrial chain have not been fully achieved [13]. In addition, the frequent occurrence of information interruption among different stakeholders makes it very difficult to control and trace the quality and safety of construction processes [14]. Only if information is shared at all stages of design, component prefabrication, transportation and assembly, can we effectively minimize loss and waste in prefabricated buildings. Under the context of Industry 4.0, a new round of science and technology revolution, the construction industry faces a historic opportunity to undergo a deep digital transformation and upgrading [15; 16]. The fusion of various emerging information technologies makes intelligent construction possible. To be specific, intelligent construction can be defined as the next-generation information technologies characterized by \"three modernization\" (i.e., digitization, network and intelligence), which are used to realize the digital transformation of the elements and resources in construction. This lays a solid foundation for standardized modeling, networked interaction, visual cognition, high-performance computing and intelligent decision-making in the whole construction process [17]. On this basis, a highly efficient and coordinated construction with an integration of project planning, design, build, operation and maintenance can be achieved. This new mode of construction provides the future development direction of prefabricated buildings. The Internet of Things (IoT), as a core part of emerging information technologies, integrates many acquisitions, communication and computing technologies [18]. It not only makes communication between people more convenient, but also enables the exchanges between people and things as well as things and things, which drives the integration of human society, information space and the physical world (i.e., human-machine-object) [19]. Therefore, applying the IoT technology to the intelligent construction system of prefabricated buildings will significantly contribute to breakthroughs tackling the current bottleneck in information interaction in prefabricated buildings. The IoT-based Intelligent Construction System for Prefabricated Buildings (ICSPB-IoT) is a system which integrates both information science development achievements and modern construction industry technologies [20].