# Development of a Multi-Radio Device for Dry Container Monitoring and Tracking
## 2 Related Works, Enabling Technologies and Standards  
Smart containers, or containers equipped with electronics allowing them to be remotely tracked and monitored, are not a new idea. If we consider only the segment of refrigerated containers, real-time reef container monitoring systems are established and affirmed technologies in the market. Nevertheless, reef containers have the particularity of being powered or having their own source of power generation; thus, the communication can be provided without particular constraints for the technologies adopted. Figure 1: A 5 GT system data flow based on different scenarios. On the other hand, the vast majority of containers, namely multimodal dry containers, have not yet become'smart' because there are still some gaps to be overcome. Any universal smart container technology that is proposed to be viable for dry containers must have the following characteristics: low-cost system, usable on all continents, easy installation and maintenance, capable of communicating in all stacking situations, robust, durable and safe, powered by long-lasting batteries. Some attempts to address this challenge are present in the literature. For example, in 2010, a hybrid system composed of two kinds of tracking devices was proposed [4]. The first kind is a \"full-function\" device equipped with a GPS receiver, transceivers to access Wi-Fi and ZigBee networks, and an RFID tag. These full-function devices require an infrastructure-based Wi-Fi network to be present on the vessel and in the yard. The second kind corresponds to \"dummy\" devices, which are only equipped with low-cost ZigBee transceivers. \"Dummy\" devices can only be tracked with the assistance of \"full-function\" devices. The limitations of this solution mainly lie in the necessity to connect the \"full-function\" devices to a Wi-Fi network, which cannot be guaranteed in all ports worldwide. Additionally, it is not realistically feasible to equip containers with two different types of trackers, \"full-function\" on some and 'dummy' on others, as containers will have different destinations during their journeys. It will be easy to find oneself in real loading situations without 'full-function' trackers because they are shipped somewhere else, hence lacking connectivity for the 'dummy' ones. Another study in 2012 was performed to retrieve the container location using an active RFID-based real-time locating system (RTLS) [5]. To evaluate the proposed method, two kinds of devices were implemented: an active RFID tag based on a low-power microprocessor and a 2.4 GHz RF module from NanoLOC placed on the containers, and some readers consisting of ARM-based PXA255 core microcomputers running embedded Linux. The method was evaluated and tested in a real container terminal environment containing many shadow areas and verified that it outperforms a least square-based localization method. However, there has not been a comparison provided with other off-the-shelf localization methods (e.g., GPS-based), and there is no subsequent commercial implementation of these devices. More recently, several researchers have explored diverse communication systems for container tracking. These include utilizing NB-IoT networks [6], satellite communications [7, 8], and even a hybrid NB-IoT approach with satellite backhauling [3]. Additional proposals suggest employing spread spectrum technologies like LoRaWAN [9], and even AIS [10], typically used for ship-to-ship communications. Hence, the potential range of communication systems applicable to container tracking is extensive, but in a highly standardized environment such as containerized logistics, only approaches that ensure compliance with global standards stand a chance of success. As an example, the experiments with an LPWAN tracking platform based on the Sigfox network [11] have created expectations in the logistic domain that are, however, running up against the low penetration of Sigfox network coverage worldwide.