# Smart Warehouse Management System: Architecture, Real-Time Implementation and Prototype Design
## 3 Literature Review  
The idea of using a smart architecture with reference to the IoT and decentralization has been widely discussed in the literature. However, the design of a reference architecture for warehouse automation is a relatively emerging field. A summary of various works performed in this context is given below. The management of a warehouse may consist of  
Figure 1: A generic display of the departments in a warehouse. managing the goods or products coming into the inventory, keeping track of the location of the items, and handling the check-outs of the finished goods. Data collection or data entry is one of the important aspects of warehouse management. Data can be of any form such as IDs, prices, or time stamps, and the data collection units can be barcode scanners, RFID readers, sensors etc. An IoT-based WMS for industries operating in the development of customized products was proposed by [28]. In this WMS, all the parts are labeled with RFID tags through which the assembling of products is handled. RFID information from these parts is sent to the Electronic Product Code (EPC) information server from whence the inventory is monitored and modified and change requests and picking faults handled. However, in this proposed work, order picking, routing, and storage plans are not discussed. [PERSON] et al. [29] described a system for inventory. When a product passes through the (in/out) gateway, its tags are read by scanners, providing information corresponding to the tag ID such as the location of the targeted products, category, product name, etc., to the forklift's screen. The driver obtains the information about the location of a particular product and picks it up, then the inventory system is updated in real time. [PERSON] et al. [30] examined the use of GPS positioning for transport fleets along with RFID shipment tracking at the entrance and departure points of the warehouse. The focus of their approach was on supply chain management through the tracking and identification module. The position tracking module uses WiFi, as it requires a high data rate and more transmission power, while the information from the position tracking module is received through a base transceiver station. RFID has been very popular for the segmentation, tracking, and positioning of products [31; 32]. The RFID reader's information is sent wirelessly to open-source hardware and the data are stored in a central server. All modules are connected over the same network for effective data communication. All the data from the warehouse are stored within a Raspberry Pi and displayed on the frontend. Similarly, a system was designed by [33] that included various environmental sensors along with RFIDs attached to the boxes. They demonstrated the use of the MQTT protocol for remote monitoring and maintenance of the storage conditions of short-lived stock items. Their proposed system also explored the efficiency of MQTT and COAP, and it was concluded that MQTT was superior to COAP in terms of data integrity, ease of implementation, and security. [PERSON] et al. [11] also proposed a heterogeneous network architecture for shipment tracking using RFIDs and a Python-stained gateway. The gateway provides subscriptions to topics through an MQTT broker, whenever a client requested them. The subscription request sent by a client is entertained and fetched by WLAN, which works efficiently due to its high transmission rate. The use of vehicles for transportation within the warehouse is very common. Traditionally, manually driven vehicles are used for transportation; however, as the architecture transitions towards the IoT, unmanned vehicles, robots, and conveyer belts are also being introduced. A system was developed by [34] for inventory regulation by using Unmanned Aerial Vehicles (UAVs). These UAVs help in the counting and localization of inventory. UAVs have the capacity to avoid obstacles and collisions. This reduces the need for critically planning and maintaining inventory tracks in the warehouse.