# Real-Time Location-Positioning Technologies for Managing Cart Operations at a Distribution Facility
## 2 Literature Review  
Real-time locating technology is an essential enabler for our proposed platform. In particular, in our motivating example, an RFID infrastructure has been established for the AMC to locate carts in real time. The applications of RFID technologies are popular in various industries, such as retail [9; 10], logistics [11] and healthcare [12; 13; 14; 15; 16; 17]. For recent detailed reviews and summaries on RFID applications, we refer the reader to the works of [PERSON] et al. [18]. RFID has been demonstrated to be an effective technology to track tagged objects. For example, it has been deployed to track components and parts of products in a job shop [19], shopping carts and apparel products [20; 21]. The objects in this research study (i.e., carts in our application) have to be tracked in a highly dynamic environment where their precise locations in real time and continuous time have to be tracked. This is highly relevant to the applications of RFID for object localization. In existing studies, RFID has also been demonstrated in successful applications for localizing people in a building [22], patients and medical equipment at hospitals [16; 17], equipment at industrial sites [23] and shopping carts in supermarket aisles [24]. The successful applications support the feasibility of RFID technology in our research. RFID has been applied extensively in supply chains; for comprehensive literature reviews, we refer the reader to the works of [PERSON] [25] and [PERSON] et al. [26]. The benefits and values of RFID technologies have also been shown in various studies. [PERSON] et al. [27] discussed three dimensions of the value proposition of RFID--technology, value measurement and incentives--and examined how business value can be extracted from the technology. There have also been analytical approaches to evaluate impacts of RFID technologies on supply chains. Inventory record inaccuracy (such as shrinkage, transaction errors and misplacement) is a pervasive problem in retail in retail supply chain [28]. [PERSON] [29] presented a supply chain model to examine the impact of inventory record inaccuracy on optimal stocking decisions and founded that it can aggravate the inefficiencies caused by double marginalization in decentralized supply chains. Assuming that RFID technologies can improve inventory record accuracy, he derived the cost thresholds that the adoption of the technologies become beneficial. [PERSON] et al. [30] developed analytical models to evaluate the benefits of item-level RFID to the manufacturer and the retailer. [PERSON] and [PERSON] [31] reviewed a number of analytical models that can help measure the value of RFID. In addition to analytical models, simulation is also able to estimate the impacts of RFID on supply chains. [PERSON] and [PERSON] [32] developed a simulation model to show that the elimination of inventory inaccuracy can reduce supply chain costs. [PERSON] et al. [33] also adopted a simulation approach to examine the tradeoffs associated with various RFID implementation strategies. [PERSON] et al. [34] considered inventory inaccuracies and used simulation to examine the effects of introducing RFID technologies on the supply chain performance. There have also been empirical studies that attempt to measure the value of RFID technologies. [PERSON] et al. [35] used data of secondary sources to examine the impacts of RFID on supply chain performance and help practitioners identify implementation areas that the technologies can be advantageous. [PERSON] et al. [36] studied the data on U.S. firms and adverted that RFID implementation expenditure is positively correlated with the expected early return on RFID investment. Furthermore, RFID can also improve product safety and security [37] and trace bad products [38] in supply chains. There has also been literature on reporting successful real-world applications of RFID in supply chains. [PERSON] et al.