## 1 Introduction  
A location-based service identifies the location of persons or objects through location awareness technology and then provides the necessary information [1]. In general, the Global Positioning System (GPS) is widely used for identifying the location of objects but has a disadvantage in that the location of objects in indoor areas cannot be grasped because the signals cannot reach there from the satellite. Furthermore, the deployment of GPS is expensive in terms of the automated tracking of individual material items [2]. Real-time locating system (RTLS) technology has been used as an alternative in indoor areas for the location-based service. Various technologies, including wireless LAN (IEEE 802.11b or Wi-Fi) [3], radio-frequency identification (RFID) [4], ZigBee [5], ultra-wideband (UWB) [6], infrared rays [7], and ultrasonic waves [8], are utilized for RTLS implementation. Recently, RTLS technology has been widely used for data management and localization in warehousing, where RFID is the most commonly used system for locating the stock [9, 10]. RFID is divided into two types, active and passive, depending on whether the tag is capable of reading and writing data and has its own power supply (battery). The active RFID type has the advantages of having its own battery, being capable of bidirectional communication with the RFID reader, and being able to transmit over long distances of over 3 m, whereas its disadvantages include having higher costs than the passive type and a limited operation time (i.e., average from 5 to 10 years) because it has its own battery [11]. Meanwhile, the passive RFID type has the merits of a simple and semi-permanently available structure, because it is powered through the radio signal from the RFID reader, and lower costs, and its disadvantage is its limited communication range because it mainly involves backscattering communication. As the active RFID type can store its own location information and transmit it to the receiver, most studies on RFID technology-based inventory location awareness have focused on the deployment of active RFID for tracking without localization [12; 13; 14] or tracking with localization [15]. Small and medium-sized enterprises (SMEs) account for 99% of all businesses and for between 50% and 60% of value added. Almost one in three people is employed in a micro firm with fewer than 10 employees and two in three in an SME. In many regions and cities, SMEs have been the main drivers of job creation and often contribute to the identity and social cohesion of local communities [16]. Most SMEs have utilized multi-stacking cracking (MSR) capable of multi-stage loading to efficiently manage their warehousing due to the lack of warehouse space and the difficulty in expanding and securing the scale of the warehouse. MSR-based inventory management allows many items to be stored in a narrow space. However, accurately identifying and managing stock locations through warehouse management, which frequently involves changing the stock location in the MSR, can be cumbersome and difficult. Thus, many SMEs desire to introduce a warehouse management system (WMS) that enables effective MSR stock location management. However, the WMS system is out of reach for many SMEs because introducing such a system requires a large amount of financial investment. For this reason, many SMEs have not adopted automated WMS and continue to manually manage their inventory location. Overall, although introducing cutting-edge technology for inventory location management is important for SMEs, more practical methods are needed to effectively manage inventory location information at a low cost. Most RFID-based indoor location tracking methods have incorporated active RFID, which enables tags to transmit the location information to an RFID reader. However, active RFID is more expensive to deploy and maintain than passive RFID, which can be an issue for many SMEs.