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%.

In this paper, we present the design, development and implementation of an integrated system for the management of COVID-19 patient, using the LoRaWAN communication infrastructure. Our system offers certain advantages when compared to other similar solutions, allowing remote symptom and health monitoring that can be applied to isolated or quarantined people, without any external interaction with the patient. The IoT wearable device can monitor parameters of health condition like pulse, blood oxygen saturation, and body temperature, as well as the current location. To test the performance of the proposed system, two persons under quarantine were monitored, for a complete 14-day standard quarantine time interval. Based on the data transmitted to the monitoring center, the medical staff decided, after several days of monitoring, when the measured values were outside of the normal parameters, to do an RT-PCR test for one of the two persons, confirming the SARS-CoV2 virus infection. We have to emphasize the high degree of scalability of the proposed solution that can oversee a large number of patients at the same time, thanks to the LoRaWAN communication protocol used. This solution can be successfully implemented by local authorities to increase monitoring capabilities, also saving lives.

Micro-level energy sources from the ambient environment can be a viable alternative to increase the life of the sensor nodes from a WSN network. Harvesting energy from the environment - particularly solar energy, is a technique that can support the operation of the sensor nodes. The power extracted from the luminous radiation is extremely variable, depending on day/night alternation, atmospheric conditions, temperature, geographical location, indoor or outdoor environment - which makes the energy harvested insufficient for use as an exclusive power source to supply sensor nodes. A special case is the indoor environment, in which the solar radiation is strongly reduced, compared to the outside environment, and artificial lighting levels are usually below 1000 Lux. We made experiments on an indoor solar cell using illumination from three different sources: fluorescent, incandescent, LED. Detailed measurements, performance comparisons, and conclusions are presented.