LoRaWAN ESL for Food Retail and Logistics

Electronic shelf labels (ESL, or electronic price tag) are used by retailers for displaying product pricing on shelves substituting printed price tags; each ESL can display not only the price, but also text, and images, and can be remotely updated, configured, and programmed from a central server. Additionally, the emerging IoT paradigm, allows to expand the application horizon. Firstly, this work presents an analysis on how the use of Cloud-connected, intelligent, ESLs can improve food logistics in the complex scenarios of medium and large cities. Then, a low-cost ESL device, using an electronic ink (e-ink) display and the LoRaWAN protocol to communicate with the central server, aimed at price display and innovative applications in food retail and logistics, is presented. Several current consumption and communication distance measurements are shown, and the design and configuration space are explored to optimize battery life and communication reliability in the different food distribution scenarios. The proposed ESL is powered with a 500mA cdot text{h} LiMnO2 battery that can last for >8 years in a typical application, considering it communicates with a central server once per hour. The developed price tag can dynamically update the price and information for the customer, which in the case of food can be used to minimize spoilage and can easily upgraded to incorporate sensors or smartphone interaction to develop innovative food logistics and marketing practices. Finally, a LoRaWAN time-slot allocation strategy is presented, to minimize collisions when thousand nodes are connected to a single gateway, with a minimum power consumption overhead.