# Energy Consumption Analysis of LPWAN Technologies and Lifetime Estimation for IoT Application
## 1 Introduction  
The Internet of Things (IoT), has gained a high momentum [1] in both industry and research community providing ease of exchange of data between application devices and sensors. The surge in the growth of IoT has shown a vast increase in the spectrum of applications like precision agriculture (PA), smart city, asset tracking, healthcare and many more [2]. Majority of these applications demands long range, low data rate with low deployment and management cost as an essential integrant. Thereby, short range radio technologies are comparatively not on high demand for high coverage applications. Wide range of data acquisition devices are already a part of IoT applications that significantly consider long range communication with low energy consumption to prolong the lifetime of the network without human intervention. Thereby, these demands have driven the emergence of Low Power Wide Area Networks (LPWANs) [3]. LPWAN is a category of wireless communication that acts as connectivity enabler to support diverse IoT applications by complimenting short and cellular wireless communication. Cellular based solutions have long connectivity but consume more energy [4]. LPWAN technology has got significantmomentum [5], mainly because of its set of features like wide range, scalable deployment, highly energy efficient, and inexpensive in regards to the cost of management, operation, and radio chip-set. It provides the link range of one to multiple kilometers with support of connecting thousands of end-devices to the infrastructure (gateway) [5]. In this paper, we have used term end-device to denote the source of data transmitted over the network. Figure 1, shows the characteristics of LPWAN technology favouring the rise in number of IoT applications. It demonstrates the set of features at different layers as an added value for numerous applications. Many licensed and unlicensed LPWAN technologies have arisen, among which the most emergent technologies are LoRaWAN, DASH7, Sigfox, and NB-IoT [6]. They have a different set of configuration parameters to regulate and position the application. The common architecture for LPWAN technologies is shown in Figure 2, which comprises of sensor devices, gateway, core network and the application. Most of the operating end-devices such as sensors and actuators are battery-operated, thereby power depletion becomes an imperative factor and needs an energy management approach to prolong the battery life. Monitoring of energy consumption is one of the crucial considerations to optimally design the network while fulfilling the application requirements. Each task that is responsible for sensing, processing, and packet transmission consumes energy which accumulates to the power consumption. Additionally, other factors also influence energy consumption that derives total lifetime of the end-device such as configuration parameters of respective LPWAN technology, type of the hardware, battery and the firmware used on the end-device. Therefore, it is crucial to investigate the characteristics of LPWAN energy consumption. However, most of the published works only focus on energy consumption to a limited extent, providing only rough estimates through simulation or investigating only one LPWAN technology. This opens up research questions: (1) Which LPWAN wireless technology is the best connectivity enabler in the context of energy consumption for the particular set of IoT applications? (2) What can be the estimated battery lifetime and how much mAh(Milliamp-hours) capacity of battery is needed for application? (3) Also, the trade-off between energy consumption calculation for the ideal case and real-time deployment. To underpin the relevance of the research questions, the following are the contributions of this paper:  
* Representation of the generic energy consumption states for LoRaWAN, DASH7, Sigfox, and NB-IoT end-device. * Real-time power consumption analysis for transmitting the data and implication of different modes of LPWAN technology concerning energy performance.