# Smart Warehouses: Rationale, Challenges and Solution Directions
## 4 Results
### RQ-3: What Are the Current Distinctive Characteristics of Smart Warehouses? A key feature of a smart warehouse is automation with no or a little human interaction. The smart warehouse is perceived as being flexible both to the environment and within the warehouse, and for it to be in constant connection with the cloud. With all sorts of tracking abilities and other forms of data gathering, data management became a crucial factor. The identified distinctive characteristics are presented in Figure 4.  
Warehouses are no longer confined to keeping large amounts of SKUs [24]. Current orders are often of low quantity and a wide variety. Modern warehouses must be highly responsive by enhancing order cycle times, cutting costs, and excelling in customer service [19]. Flexibility is key in a changing environment, and reducing the total cycle time ensures smooth inbound and outbound logistics, including amongst others stock accuracy, process management, space utilization, and optimized picking [3; 30]. The goal is to \"allocate minimum warehouse resources and satisfy customer demands within a short period of time\". To optimize order-picking, the concept of order-batching will be a crucial element [19]. The concept of public warehouses (PW) anticipates this where small quantities of goods are delivered when requested [24]. Current automated warehouses are often known for having manually operating [22] or programmed equipment. Examples of this equipment are AGV [20], palletizing robots, carton flow racks, rotary storage cabinets, and AS/RSs [13]. Automated storage and retrieval system (AS/RS) is a material handling mechanism that is a key element of automated warehouses or distribution centers [26]. Automated guided vehicle systems (AGVS) are used as their movements are directed and programmed by sensors, which enables more flexibility in the routing and dispatching [15]. Optimization is also increased efficiency and technological support for processes that cannot be technologically atomized [27; 28]. [PERSON] and [PERSON] [18] argue to integrate an auto-access multi-level conveying device (IMCD) into the AS/RS to enable three-dimensional movement through conveyors. WMSs have tracking abilities through RFID [24; 25]. An RFID-inventory management system is a part of future generation automated warehousing systems [14; 26]. RFID-based order scheduling and execution monitoring system (RFID-OSEMS) combines the advanced data collecting performance of RFID with real-time data-based order scheduling to coordinate all order handling devices [24]. The RFID-OSEMS has two subsystems (1) real-time order scheduling (RTOS), storing and retrieval (R/S) orders from different customers are stored in an order pool, and (2) an RFID-based order executing and monitoring (ROEM). ROEM is the joint of four sub-models (1) RFID configuration strategy (RFCS) creating a ubiquitous monitoring environment through the use of different types of RFID devices, (2) RFID-based order executing (RFOE), which reduces order executing time and facilitates the collection of related data, (3) real-time data collecting (RTDC) on-site by vehicle-mounted RFID readers, and (4) RFID-based executing monitoring (RFEM), which processes all data and is in direct contact with the RTOS in case rescheduling is needed, creating a closed-loop system [24]. Hub processors for RFID data flow are used to pre-process  
Figure 4: Summary of the frequency of current distinctive characteristics. the data and provide classified, filtered, and uniform data for all systems. This will form the basis for an IoT-based warehouse [16]. WMSs have tracking abilities through IoT [25; 30]. A WMS integrated with autonomous components which support the communicating object (CO), having intelligent interactions and decision making, will turn this IoT-based system towards a smart warehouse system [23; 32]. IoT can be apportioned into a sensor, transmission, and application network [30].