# Ultra-Low-Power Wide Range Backscatter Communication Using Cellular Generated Carrier +
## 1 Introduction  
The smart city is the integration of information and communication technology (ICT) into the classical city infrastructure in order to digitize the information and the processes that are involved in the management of a city [1]. In smart city, the data from different sources are collected by smart sensors, which often use the ecosystem of the Internet of Things (IoT) and, later, these data are analysed and shared with other systems. The collected data are not only used for efficient utilization of resources but also to reduce the operational cost of a city [1]. Therefore, the IoT has numerous applications in the monitoring of urban systems, such as water and electricity metering, controlling public street lights, updating public transport status, and waste management in public areas. The IoT deployments for smart city applications only require the sensors to collect and transmit a small amount of data. In recent years, we have witnessed the developmentand deployment of low-power sensor networks of different radio technologies, such as LoRa, SigFox, NB-IoT, and Bluetooth low energy (BLE). These technologies have made a trade-off between the data rate and the coverage i.e., decreased the former to increase the latter, and the sensors utilizing these technologies are often powered with built-in batteries. However, in general, the large scale deployments of IoT networks of these technologies are mainly limited by cost, energy consumption, and the congestion of the communication medium [2]. In particular, their significant power consumption also brings forth the inconvenience of maintaining and replacing the batteries in order to accommodate a long range communication. Therefore, an alternative ICT that not only enables ultra-low-power communications rather also supports a large coverage area, while not overloading the scarce communication spectrum is needed, in order to realize the massive IoT deployments for smart cities. Backscatter communication (BC) has recently emerged as an energy efficient ICT technology that provides optimized solutions to the requirements of smart city applications [3]. This radio technology alters the RF signal, impinging it at the antenna without using power-hungry and expensive radio frequency (RF) electronics so that significant cost and power savings are obtained. The BC devices can operate on licensed communication spectrum since they do not affect the operation of other systems [4]. These advantages come at the cost of significantly lower signal levels at the receivers and, thus, the data rate and the coverage of BC are limited [2]. Despite these limitations, the aforementioned advantages have led the researchers from both academia and industry to investigate the possibilities that are enabled by this ICT in application fields. such as smart agriculture, digital healthcare, and industrial automation [5]. To the best of our knowledge, the coverage of BC for large-scale deployment of BC for smart-city applications is not available in the literature and, thus, the feasibility of this ICT for smart city applications is not known. Targets and Key ContributionsIn this article, we investigate the feasibility of BC, which is driven by a carrier signal that is generated by available cellular system base stations, in terms of coverage that can be achieved. In particular, we evaluate the outage ratio of a BC system based on the receiver sensitivity level of different low-power wide area technologies through a comprehensive set of simulations in an urban city environment. Here, the target is to evaluate the viability of cellular network based BC system in a downtown area of Helsinki city with practical system parameters. The simulation work is carried out by using a hybrid approach of deterministic ray tracing model, 3 GPP indoor hotspot model, and ITU-R device-to-device (D2D) outdoor model. The intent of this research work is to provide practical insights for a commercial _large-scale BC system_ from the coverage planning and deployment point of view.