In recent years the IoT concept is more and more powerful, having set the goal of integrating billions of devices to the Internet. Thus, from this perspective, the interest allocated to low-power wireless networks of sensors is higher than ever. In this paper, the SigFox scalability is analyzed from the IoT concept point of view. In the scientific research, there are a series of papers which tackle the SigFox issues, oftentimes at a comparative study level, without evaluating the performance level of the communication protocol. This paper comes to fill this gap by creating a realistic SigFox communication model. Moreover, a developed and tested generator of SigFox traffic has been implemented, using SDRs. This allows the possibility of evaluating the performance level of WSN networks, of a large-scale high-density type. Both of the suggested instruments represent the novelty of this paper. The obtained results show that the maximum number of sensors that can transmit data at the same time, using the proposed scenarios, is of approximately 100, in order to obtain a high level of performance when the number of available channels is 360. If we are to increase the number of sensors, an avalanche effect ensues which triggers the sharp decrease of the performance of the SigFox network. At the end of this work, a series of solutions are being suggested with the main purpose of increasing the performance level of large-scale, high-density SigFox networks.

The Internet of Things (IoT) concept involves connecting devices to the internet and forming a network of objects that can collect information from the environment without human intervention. Although the IoT concept offers some advantages, it also has some issues that are associated with cyber security risks, such as the lack of detection of malicious wireless sensor network (WSN) nodes, lack of fault tolerance, weak authorization, and authentication of nodes, and the insecure management of received data from IoT devices. Considering the cybersecurity issues of IoT devices, there is an urgent need of finding new solutions that can increase the security level of WSNs. One issue that needs attention is the secure management and data storage for IoT devices. Most of the current solutions are based on systems that operate in a centralized manner, ecosystems that are easy to tamper with and provide no records regarding the traceability of the data collected from the sensors. In this paper, we propose an architecture based on blockchain technology for securing and managing data collected from IoT devices. By implementing blockchain technology, we provide a distributed data storage architecture, thus eliminating the need for a centralized network topology using blockchain advantages such as immutability, decentralization, distributivity, enhanced security, transparency, instant traceability, and increased efficiency through automation. From the obtained results, the proposed architecture ensures a high level of performance and can be used as a scalable, massive data storage solution for IoT devices using blockchain technologies. New WSN communication protocols can be easily enrolled in our data storage blockchain architecture without the need for retrofitting, as our system does not depend on any specific communication protocol and can be applied to any IoT application.

The Internet of Things (IoT) has become a part of modern life where it is used for data acquisition and long-range wireless communications. Regardless of the IoT application profile, every wireless communication transmission is enabled by highly efficient antennas. The role of the antenna is thus very important and must not be neglected. Considering the high demand of IoT applications, there is a constant need to improve antenna technologies, including new antenna designs, in order to increase the performance level of WSNs (Wireless Sensor Networks) and enhance their efficiency by enabling a long range and a low error-rate communication link. This paper proposes a new antenna design that is able to increase the performance level of IoT applications by means of an original design. The antenna was designed, simulated, tested, and evaluated in a real operating scenario. From the obtained results, it ensured a high level of performance and can be used in IoT applications specific to the 868 MHz frequency band.By inserting two notches along x axis, we find an optimal structure of the microstrip patch antenna with a reflection coefficient of −34.3 dB and a bandwidth of 20 MHz. After testing the designed novel antenna in real IoT operating conditions, we concluded that the proposed antenna can increase the performance level of IoT wireless communications.

Energy management efficiency is a topical issue for Internet of Things (IoT) sensor networks because a sensor can be placed in harsh or hardly accessible places and must transmit data without maintenance. One characteristic of the LoRa technology is the high current peaks during the data transmission procedure. These current peaks can decrease the lifetime of the conventional power sources. Thus, to protect the conventional battery of the wireless sensor from degradation during fast discharging, a hybrid energy storage system can help. This article presents the design and development of a LoRaWAN sensor powered by a hybrid energy storage system and an energy management solution that can be integrated into the node. The novel solution presented integrates a 330-mW photovoltaic (PV) panel as a main source, a 4-F supercapacitor and a 230-mA small form factor Lithium battery as backup and it was tested in a real IoT application. Currently, as the most used solution to increase the battery lifetime of a LoRaWAN sensor is to reduce the communication time with the Gateway, our hybrid power management system comes with a solution for the node to be powered for a very long period of more than two years in worst case scenario configuration when the PV panel is not installed and more than ten years with hybrid power solution, without the compromise of reducing the communication time. The achieved communication distance is about 580 m with SF7 and more of 2 km with SF12 in an urban area.

The digital revolution has changed the way we implement and use connected devices and systems by offering Internet communication capabilities to simple objects around us. The growth of information technologies, together with the concept of the Internet of Things (IoT), exponentially amplified the connectivity capabilities of devices. Up to this moment, the Long Range (LoRa) communication technology has been regarded as the perfect candidate, created to solve the issues of the IoT concept, such as scalability and the possibility of integrating a large number of sensors. The goal of this paper is to present an analysis of the communication collisions that occur through the evaluation of performance level in various scenarios for the LoRa technology. The first part addresses an empirical evaluation and the second part presents the development and validation of a LoRa traffic generator. The findings suggest that even if the packet payload increases, the communication resistance to interferences is not drastically affected, as one may expect. These results are analyzed by using a novel Software Defined Radio (SDR) technology LoRa traffic generator, that ensures a high-performance level in terms of generating a large LoRa traffic volume. Despite the use of orthogonal variable spreading factor technique, within the same communication channel, the collisions between LoRa packets may dramatically decrease the communication performance level.

The interest in developing systems working with IoT platforms is increasing nowadays. Thus, many smart sensors can communicate over the Internet without human mediation using LPWAN networks. This paper presents a low-cost high-performance multi-channel Gateway for LoRaWAN technology. In order to validate the Gateway performances, the TTN cloud data network it’s used. The configuration of the Gateway consists of a Raspberry Pi 3B+ and an iC880A concentrator LoRa Gateway board. The Gateway is certified by LoRaWAN Alliance and supports multichannel communication. Also, the system integrates a 2.2 dBi Omnidirectional antenna. From the performed measurements, the Gateway ensures a high level of performance and a maximum communication distance of 2.5 km in rural areas, and 1.3 km in urban areas with a PER of less than 20%.