# Energy Consumption Model for Sensor Nodes Based on LoRa and LoRaWAN
## 2 Related Works and Contributions  
LoRa and LoRaWAN technologies are relatively recent standards [11]. Most existing research based on LoRa and LoRaWAN has focused on features such as delay, range, throughput and network capacity [8; 11; 12; 13]. Since the LoRa modulation is deployed for sensor applications, several papers evaluated this new technology with respect to its energy consumption. Driven by the challenges of energy consumption of wireless sensor applications, many recent works have focused on the power dissipation of communicating sensors. [PERSON], et al. present an energy model for Ultra-Low Power sensor nodes in [14; 15]. In these papers, the authors described the modeling of a sensor node dedicated to wireless sensor network applications. However, the RF module used in this study was the _CC1100_ module (a short range device) which did not include the LoRa technology. An other energy estimation model is presented in [16], The goal of this work is to obtain a low power consumption of sensor nodes. To save power, [PERSON] et al. have concluded that the communication module and the microcontroller must be in idle state as long as possible when they are not active. This work proposes interesting results, but LoRa and LoRaWAN technologies are not integrated into this study. [PERSON], et al. proposed a comparison of LoRaWAN classes and their power consumption in [17]. The objective of this study is to offer an experimental comparison of LoRaWAN classes to verify the published current levels of different operating modes in LoRa datasheets. The measurement results allow to estimate the lifetime of end-node devices. However, in this paper, the authors did not study the effect of different LoRaWAN parameters such as coding rate, communication range and transmission power level on the total consumed energy. Many other studies provide the power consumption of sensor nodes based on LoRa/LoRaWAN. Most of the current values were obtained from the datasheet or by empirical means [18; 19; 20], without developing an energy model that can estimate and optimize the energy consumption of the wireless sensors. [PERSON], et al. developed current models that allow the characterization of LoRaWAN devices lifetime and energy cost in [21]. The proposed models were very important and derived from measurement results using a currently prevalent LoRaWAN platform. However, [PERSON], et al. did not include the energy consumption of the processing and the sensor units. In our paper, we have modeled these units for an application scenario of connected sensor. Another major difference is that we have illustrated our energy model with optimization of LoRaWAN parameters such as the spreading factor \(SF\), the coding rate \(CR\), the bandwidth \(BW\), the payload size and the communication range. Optimizing these parameters is very important to reduce the energy consumption of the sensor node. The previous works were proposed to estimate the amount of energy consumption by a sensor node. Some of these studies have not included LoRa technology into their energy models, so they used different RF transceivers which are mainly dedicated to short range communication. Other works did not study the energy optimization of sensor nodes. In fact, optimizing LoRa and LoRaWAN parameters are very interesting to reduce the energy consumption by the communicating sensor. To estimate and optimize the consumed energy by the sensor node, we propose a full energy model based on LoRa/LoRaWAN technologies. This model is based on LoRaWAN Class A, which is the most energy efficient class in the protocol. The proposed model takes into account the modeling of the sensor node units and especially the processing and the sensor units using a real IoT application. Then, different LoRaWAN transmission modes are studied to choose the best mode that can optimize energy consumption.