## 8 Conclusions  
During storage and transportation of perishable commodities, several environmental factors should be kept within recommended thresholds to preserve quality throughout the supply chain, maximizing their shelf life. Temperature is the most important environmental factor affecting quality; however, most of the temperature control systems used in transportation media do not have multi-point measurement and temperature-recording systems,  
Figure 16: Evolution of the temperature between the two node locations at different temperatures: (**a**) 10 \({}^{\circ}\)C; (**b**) 5 \({}^{\circ}\)C; (**c**) 2 \({}^{\circ}\)C.  
Figure 15: Distribution of the nodes during land transportation.  
which are based on temperature cards or tags, and also do not have real-time communication protocols to know the conditions in which the commodities are being stored.  
Due to the thermal differences observed in the tests, the real-time knowledge of such conditions during storage and transportation can be used not only as a warning mechanism, but also as a tool for predicting shelf life.  
In this sense, a portable, multi-configurable system with real-time communication is presented in this paper.  
The main advantages of the designed system over other similar devices are that it combines the measurement of multiple parameters with the flexibility of sending the measured information through Wi-Fi networks, whose infrastructure is widespread and easy to install. However, the Wi-Fi infrastructure is a broadband network, and therefore, its energy consumption is higher than other wireless technologies such as SigFox, LoRa or ZigBee. Therefore, to be able to use this technology taking advantage of the aforementioned advantages with sufficient autonomy, specific time synchronization algorithms were developed to allow for device usage ranges greater than 28 days.  
On the other hand, the temperature and humidity conditions of the different stages of the supply chain affect the quality of data transmission, with tests showing data loss rates of less than 10% even in unfavorable conditions. Temporary storage of unsent data allows data to be sent when transmission conditions are favorable.  
The main disadvantage is that the devices cannot be used for maritime transport as designed. The metal containers typically used in this type of transport affect the data transmission capacity. This could be solved by installing external antennas, although this would affect the ease of installation of the nodes. On the other hand, in the ocean there is no coverage for networks such as Sigfox, LoRa or NB-IoT, but ships usually have Wi-Fi communication (with satellite networks such as Iridium), so the nodes described in this article could be valid for this type of transport.  
Regarding the use of the system by the agents involved in the supply chain, the main drawback observed was the programming of the nodes with the different networks (SSIDs and passwords) that the commodities were going to travel through during the journey from the harvest to the warehouse. This problem was solved by means of the APP, which allows the nodes to be programmed in an intuitive way with the different configurations. However, the input of the information is manual, and errors can be made that can cause the system to malfunction. For this reason, in future work, we proposed to improve the configuration system by using QR coding associated with the product and the route it will follow to the destination, making it unlikely that errors will be made when entering the information of the different Wi-Fi networks. On the other hand, the QR coding will allow for access to the traceability of the product conditions during the whole process. As future research, further experiments will be conducted to compare our proposal with other systems using different communication technologies.