Alexandru Lavric

The design of a street lighting monitoring and control system

Increasing the efficiency and automation of lighting control systems is an important issue that has been addressed by many research centers. This paper presents the design and implementation of a lighting monitoring and control system that can be employed for street lighting control. The main advantages of this system consist in substantially reducing the costs related to energy consumption and maintenance, by dimming the light intensity using vehicle detection. The system architecture is based on a WSN (Wireless Sensor Network) communication protocol.

Street lighting control system based on large-scale WSN: A step towards a smart city

This paper presents the field testing of a street lighting monitoring and control system. The system is based on a WSN network of the large-scale type that enables the remote control of street lighting lamps. The system also enables savings in terms of the electric power and maintenance costs. The architecture uses integrated Doppler sensors that allows for vehicle detection and help complete the power efficiency objective. Thus, when a vehicle is detected the light intensity of the lamps is increased to a preset level, so as not to affect road traffic safety, and reduced in the opposite case. Moreover, the system uses current sensors so as to allow for the identification of any possible malfunctions and thus facilitate the maintenance process. According to the obtained results, the system allows for an increased performance level and can be integrated in the Smart City concept.

Performance evaluation of Power Line Communications over power transformers

Power Line Communications (PLC) are used in Automatic Meter Reading (AMR) systems more and more this day. This paper analyses the problems encountered when the PLC signal is needed to be sent through the body of a power transformer, we have made field tests to verify if communication can take place and with what performances. For this a comparative analyze of protocols PRIME and G3-PLC data transfer has been made, when communication took place as follow: through the secondary winding of a MV/LV power transformer from a phase to another, through two power transformers from one secondary LV winding to the other one secondary LV winding over the MV power line that feeds the both of them, and through the second power transformer when distance on one phase was increased to 50 m. Parameters as BER (Bit Error Rate), PER (Packet Error Rate), data rate the signal spectrum are analyzed.

A mathematical approach of a HF RFID multi loop antenna for metallic environments

The most important factors that may influence and affect the performance of HF RFID systems that use passive tags, consists in the effects of the metallic environments in the proximity of the antenna. In order to overcome a part of these issues, both the device antennas and their impedance matching units must be optimized. This paper presents a mathematical model that enables the identification of the optimal size of a multi loop HF RFID antenna that would encompass the coordinates of a given surface. The antenna has been mathematically modeled, simulated and tested for a specific situation when the metal plate is positioned in its close proximity.

Internet of Things and LoRa™ Low-Power Wide-Area Networks: A survey

Nowadays there is a lot of effort on the study, analysis and finding of new solutions related to high density sensor networks used as part of the IoT (Internet of Things) concept. LoRa (Long Range) is a modulation technique that enables the long-range transfer of information with a low transfer rate. This paper presents a review of the challenges and the obstacles of IoT concept with emphasis on the LoRa technology. A LoRaWAN network (Long Range Network Protocol) is of the Low Power Wide Area Network (LPWAN) type and encompasses battery powered devices that ensure bidirectional communication. The main contribution of the paper is the evaluation of the LoRa technology considering the requirements of IoT. After introduction in Section II the main obstacles of IoT development are discussed, section III addresses the challenges and entails the need for solutions to different problems in WSN research. Section IV presents the LoRaWAN communication protocol architecture requirements while in Section V the LoRa modulation performance is evaluated and discussed. In conclusion LoRa can be considered a good candidate in addressing the IoT challenges.

Internet of Things and LoRa™ low-power wide-area networks challenges

Nowadays there is a lot of effort on the study, analysis and finding of new solutions related to high density sensor networks used as part of the IoT (Internet of Things) concept. LoRa (Long Range) is a modulation technique that enables the long-range transfer of information with a low transfer rate. This paper presents a review of the challenges and the obstacles of IoT concept with emphasis on the LoRa technology. A LoRaWAN network (Long Range Network Protocol) is of the Low Power Wide Area Network (LPWAN) type and encompasses battery powered devices that ensure bidirectional communication. The main contribution of the paper is the evaluation of the LoRa technology considering the requirements of IoT. In conclusion LoRa can be considered a suitable candidate in addressing the IoT challenges.

LoRa™ wide-area networks from an Internet of Things perspective

In recent years, there are many discussions about the IoT (Internet of Things) concept. LoRa (Long Range) modulation together with LoRaWAN (LoRa Wide-Area Networks) communication protocol can represent a suitable candidate ensuring a high level of performance. The main contribution of the paper is the performance evaluation of the LoRa technology considering the requirements of IoT. In the first part of this paper LoRa technology is summarized by reviewing some aspects regarding the architecture and the security of the technology, meanwhile in the second part of the paper are presented some simulation scenarios. From the obtained results, by simply varying the SF (Spreading Factor) parameter the communication distance and robustness to interferences can be increased, meanwhile the data rate is reduced.

Performance evaluation of WSN topology control algorithms that can be used in the Smart City concept

Smart City concept is a topical issue. The main contribution of this paper is the performance evaluation of topology control algorithms that can be integrated in the Smart City concept. Thus, the following topology algorithms A3, A3 Coverage and EECDS are considered. The parameters evaluated are: the number of active nodes after the topology reduction algorithm is applied, the number of packets sent and the energy consumed for building the topology. From the obtained results we conclude that the topology construction algorithm A3 provides the lowest number of active nodes and is recommended for use in the Smart City concept.

Performance evaluation of 13.56 MHz RFID antenna operating in metallic environments

The present paper analyses and measures the effects that the presence of a metallic surface can induce on the integrated antennae of HF RFID systems operating on a 13.56 MHz frequency. The results of the conducted measurements have been compared with those arrived at by means of the Ansoft HFSS application. Thus, the conducted tests and simulations reveal the fact that the resonant frequency increases in direct ratio to the distance between the loop antenna and a parallel metallic surface. When the antenna is positioned within less than 3 cm from a metal surface, its performance is drastically reduced and the resonant frequency increases from 13.56 MHz to 14.75 MHz, which eventually compromises the entire communication process, since the interrogation zone is considerably reduced. Further analyses are conducted on the influences exerted on the performance of the antenna, which is made from various materials, such as copper or aluminium. Apart from the detailed account of these issues, we also suggest a series of solutions that will eventually enable the expansion of the interrogation zone.

Performance Evaluation of LoRaWAN Communication Scalability in Large-Scale Wireless Sensor Networks

The LoRaWAN communication protocol can be used for the implementation of the IoT (Internet of Things) concept. Currently, most of the information regarding the scalability of the LoRa technology is commercial and deals with the best-case scenario. Thus, we need realistic models, enabling the proper assessment of the performance level. Most of the time, the IoT concept entails a large number of nodes distributed over a wide geographical area, therefore forming a high density, large-scale architecture. It is important to determine the number of collisions so that we can assess the network performance. The present paper aims at assessing the performance level of the LoRaWAN technology by analyzing the number of packet collisions that can occur. Thus, this paper determines the maximum number of LoRa nodes that can communicate with a Gateway considering the LoRaWAN protocol specifications. Furthermore, we have proposed a series of solutions for reducing the number of collisions and increasing the capacity of the communication channel.