# Next Generation Wireless Technologies for Internet of Things
## 2 A Review of the Contributions in This Special Issue
In [6], the primary aim of the authors is to prove that multi-model distribution of the received signal strength indicator (RSSI) is linked to the signals' modulation schemes and medium access mechanisms, and RSSI from different technologies may present very peculiar characteristics. An experimental study is carried out, and the results prove that even RSSI obtained at a sub-Nyquist sampling rate can give sufficient peculiarities to separate technologies such as Wi-Fi, Long Term Evolution (LTE), Digital Video Broadcasting-Terrestrial (DVB-T) and Bluetooth. On the contrary, the authors of [7] present a state-of-the-art survey explicitly intended for examining middlewares with the quality of context support. Furthermore, they propose a middleware of this type, suitable for IoT applications, which combines the use of a mobile gateway with a data distribution service. The main aim of the suggested middleware is to meet several requirements related to the specific IoT application. The performance evaluation shows that the data processing time of the middleware components is relatively low. Also, a small impact on the total delivery time is needed for communication between data producers and consumers. The most significant number of papers accepted in the special issue has concentrated on proposing innovative applications, in different contexts, suitable for the Internet of Things. For instance, the authors of [8] suggest the use of virtual objects to control and manage the various resource-constrained objects that define the IoT, with the aim to determine those that can accomplish some specific tasks guaranteeing the required quality of information. To this end, they propose a consensus-based algorithm where the resources of these objects are designated for the execution of tasks so that the workload is allocated in a fair way. Tests on real devices prove that the proposed algorithm can obtain a concrete improvement concerning the average lifetime. A Smart Collaborative Caching (SCC) scheme is introduced in [9] with the aim to support an information-oriented IoT establishment. The authors provide details on several features, such as the cluster composition, content processing, and position management. Moreover, four representative SCC actions and appropriate algorithms are also analyzed. The results obtained in a validation topology composed of two scenarios prove that the performance of the proposed scheme, concerning total packet number and average transmission latency, can outperform that of the original ones. As future works, the authors aim to examine the applicability of SCC in numerous scenarios and further optimize the data exchange processes. The authors of [10] present the results from three-years of constant monitoring of environmental conditions employing a wireless sensor network established in an art museum. The proposed solution is based on several sensors to gather the temperature and air flow and to evaluate microclimate changes using physics-based and statistical models. The results exhibited by the authors confirm not only the effectiveness of monitoring through their platform but that in specific contexts the installation of a wireless sensor network may be the best choice since it is less invasive compared to a wired solution. On the contrary, the problem of estimating the location of multiple individuals moving and interacting in an indoor space is analyzed in [11]. In this case, the authors propose a multi-sensor data-fusion framework, relying on a unifying location-estimate representation as a confidence map of the indoor space. The effectiveness concerning the deployment of a wireless sensor network is also proven in this context because the results regarding the indoor localization are very encouraging. The authors of [12] focus on the problem of target location in belt-type sensor networks. In the proposed solution, an energy-efficient strategy is utilized to dispose of IoT nodes.