# Compressive Sensing-Based IoT Applications: A Review
## 2 IoT Framework  
The international telecommunication union (ITU) defines the IoT as a global infrastructure for the information society, enabling advanced services by interconnecting (physical and virtual) things based on existing and evolving interoperable information and communication technologies [17].  
IoT consists of a network of sensors, actuators, wireless communication protocols and data processing technologies that interact with each other to provide a specific application [18]. IoT is often characterized by a large number of highly dynamic heterogeneous devices each with different and limited communication and computation resources. This heterogeneity in both the software/hardware levels requires a new level of networking/communication protocols as well as adaptation mechanisms [19]. Moreover, several other issues have to be addressed as well in both the integration and the management of these devices, such as scalability, information exchange, power consumption, interoperability and system flexibility for the dynamic change in the network topology [20]. Moreover, IoT has shifted the applications from the scale of a single device to real-time massive deployments of embedded cross-platform and cloud technologies. Therefore, to link everything together, several research groups and standardization bodies have approached and addressed these issues from several perspective [21].  
Subsequently, different architectures have been proposed in the literature to establish a universal framework for IoT applications. These architectures take into consideration several parameters related to the IoT devices, the communication protocols, the networking and the targeted applications and services. For instance, a three-layer IoT platform consisting of a perception layer, a communication layer and a service layer has been proposed in [22; 23]. [PERSON] et al. considered an IoT architecture of four layers, namely physical, transport, middleware and application layers [24]. A five-layer IoT platform consists of perception layer, processing layer, transport layer, application layer and the business layer has been proposed in [25]. Table 1 summarizes a three-layer IoT platform with a brief description of the functionality of each layer. The IoT platform presented in Figure 1 consists of several sensors that can be deployed to gather information about the different physical phenomenon, these sensors are interconnected through a wireless network and communicate with a local processing unit where the data can be stored and lightweight processing can be performed. Afterwards, data are routed to the application layer hosted on the cloud where different data analytic algorithms can be applied to provide explicit services.  
IoT platforms have evolved rapidly in the last decade by leveraging the interactions among different types of smart devices, such as vehicles, medical sensors, cameras and RFID systems. Subsequently, a wide range of applications has been enabled, for instance, experimental monitoring, automated industry, connected health-care, smart buildings, intelligent transportation systems (ITS), smart grid, etc. [26]. Moreover, growing interest has been dedicated to incorporate IoT platforms in an environmental context. Strong efforts have been made by several national governments and leading information technology (IT) companies to adopt IoT solutions in the development of smart cities [27]. Even though a unified smart city framework has not been clearly defined yet, all the effort to develop this sector of applications aims to fully exploit any public resource to enhance the quality of the services offered to the citizens [28]. Smart cities can provide assistance for public service management. These services include transportation [29, 30, 31], city surveillance and emergency management [32, 33], preservation of cultural heritage [34] and environment monitoring [4, 28, 35].