## 1 Introduction  
The construction industry generates considerable economic activity and contributes to the growth of nations. The construction industry involves the coordination and the collaboration of a number of firms and organizations engaged in the process of building a facility. Despite the importance of this industry to the economy, it has historically been criticized for low productivity compared to other industries [1]. Some of these productivity issues relate to the large number of stakeholders involved in a construction project and the communication process among them [2]. A lack of innovation in the construction industry has been listed as one of the multiple reasons resulting in low productivity [3]. This shows the importance of implementing new technologies that ease collaboration of all parties involved through effective communication mechanisms. Augmented reality (AR) is one of the emerging technologies that can be used in the construction industry, which involves overlaying virtual objects on the existing real environment so that it appears as if they are both present at the same time [4]. In the construction industry, AR has been explored in many fields including communication [5], visualization [6], inspection [7], and education [8]. Communication is a method of exchanging information in real time or with a time lag between two or more parties [9]. Asynchronous communication is a method of interaction that does not happen in real time [10]. To facilitate synchronized communication between an on-site user and an off-site user with AR, an online platform can be utilized (e.g., Microsoft Dynamics 365 Remote Assist). This approach enables individuals in remote locations to communicate with each other using AR. Off-site users can elect to use traditional computers to create and view AR annotations, while field users can elect to use head-mounted displays (e.g., Trimble XR 10 and Lynx R-1) or handheld devices for AR interaction [11]. Figure 1 represents a strategy for facilitating synchronous AR communication in order to illustrate the fundamental aspects of AR that support synchronous communication in the construction industry. This figure highlights how different types of users (top) may interact with different hardware (middle) through a common software (bottom) in order to support synchronous AR communication between on- and off-site individuals. While there have been numerous studies that have explored the trends of using AR for asynchronized communication [12; 13; 14], there is a noticeable gap in the literature regarding comprehensive reviews of trends specifically focusing on real-time communication (i.e., synchronized communication) across various contexts. Conducting such studies would greatly benefit practitioners by providing a deeper understanding of the advantages offered by AR for synchronized communication, the challenges encountered in its implementation, and the specific contexts where AR is most effective or needs to be approached with caution. This study explores the literature on the topic of using AR for synchronized communication in order to answer the following two main questions:  
1. What attributes related to AR for synchronized communication are consistently reported by researchers to be either challenging or beneficial? 2. For the attributes where researchers diverge in characterizing the benefits or drawbacks, what contextual elements within the papers differ in a manner that may contribute to the differing reports? This paper aims to identify the contexts in which AR has been implemented for synchronized communication, while also examining the benefits and challenges reported by AR researchers in the industry. An understanding of this information is important and critical, especially since the application of AR in the construction industry is being constantly developed and different studies may show divergent trends. For example, some studies  
Figure 1: Off-site and on-site users’ hardware and software.