Konstantin Mikhaylov

On the coverage of LPWANs: range evaluation and channel attenuation model for LoRa technology

In addition to long battery life and low cost, coverage is one of the most critical performance metrics for the low power wide area networks (LPWAN). In this work we study the coverage of the recently developed LoRa LPWAN technology via real-life measurements. The experiments were conducted in the city of Oulu, Finland, using the commercially available equipment. The measurements were executed for cases when a node located on ground (attached on the roof rack of a car) or on water (attached to the radio mast of a boat) reporting their data to a base station. For a node operating in the 868 MHz ISM band using 14 dBm transmit power and the maximum spreading factor, we have observed the maximum communication range of over 15 km on ground and close to 30 km on water. Besides the actual measurements, in the paper we also present a channel attenuation model derived from the measurement data. The model can be used to estimate the path loss in 868 MHz ISM band in an area similar to Oulu, Finland.

Performance Analysis and Comparison of Bluetooth Low Energy with IEEE 802.15.4 and SimpliciTI

Bluetooth Low Energy (BLE) is a recently developed energy-efficient short-range wireless communication protocol. In this paper, we discuss and compare the maximum peer-to-peer throughput, the minimum frame turnaround time, and the energy consumption for three protocols, namely BLE, IEEE 802.15.4 and SimpliciTI. The specifics and the main contributions are the results both of the theoretical analysis and of the empirical measurements, which were executed using the commercially available hardware transceivers and software stacks. The presented results reveal the protocols’ capabilities and enable one to estimate the feasibility of using these technologies for particular applications. Based on the presented results, we draw conclusions regarding the feasibility and the most suitable application scenarios of the BLE technology.

Evaluation of LoRa LPWAN technology for remote health and wellbeing monitoring

Low power consumption, low transceiver chip cost and large coverage area are the main characteristics of the low power wide area networks (LPWAN) technologies. We expect that LPWAN can be part of enabling new human-centric health and wellness monitoring applications. Therefore in this work we study the indoor performance of one LPWAN technology, namely LoRa, by the means of real-life measurements. The measurements were conducted using the commercially available equipment in the main campus of the University of Oulu, Finland, which has an indoor area spanning for over 570 meters North to South and over 320 meters East to West. The measurements were executed for a sensor node operating close to human body that was periodically reporting the sensed data to a base station. The obtained results show that when using 14 dBm transmit power and the largest spreading factor of 12 for the 868 MHz ISM band, the whole campus area can be covered. Measured packet success delivery ratio was 96.7 % without acknowledgements and retransmissions.

Multihop data transfer service for Bluetooth Low Energy

Bluetooth Low Energy (BLE) is one of the recently developed protocols enabling energy-efficient short-range radio communication. One of limitations of BLE is the support for data transferring over only a single hop. In the paper, we suggest the mechanism enabling the multihop data transfers between the nodes in BLE networks. To ensure portability, the suggested mechanism is designed as BLE service, which uses only the integral components of BLE stack. We discuss in details the suggested multihop service, its implementation and present the results of evaluation, which confirm feasibility and reveal features of the suggested solution. To the best of our knowledge, this paper reports the first implementation of the multihop data transfer over the BLE networks.

Performance of a low-power wide-area network based on LoRa technology : Doppler robustness, scalability, and coverage

The article provides an analysis and reports experimental validation of the various performance metrics of the LoRa low-power wide-area network technology. The LoRa modulation is based on chirp spread spectrum, which enables use of low-quality oscillators in the end device, and to make the synchronization faster and more reliable. Moreover, LoRa technology provides over 150 dB link budget, providing good coverage. Therefore, LoRa seems to be quite a promising option for implementing communication in many diverse Internet of Things applications. In this article, we first briefly overview the specifics of the LoRa technology and analyze the scalability of the LoRa wide-area network. Then, we introduce setups of the performance measurements. The results show that using the transmit power of 14 dBm and the highest spreading factor of 12, more than 60% of the packets are received from the distance of 30 km on water. With the same configuration, we measured the performance of LoRa communication in mobile scenarios. The presented results reveal that at around 40 km/h, the communication performance gets worse, because duration of the LoRa-modulated symbol exceeds coherence time. However, it is expected that communication link is more reliable when lower spreading factors are used.

Optimization of microcontroller hardware parameters for Wireless Sensor Network node power consumption and lifetime improvement

In this article the results for study of the influence of different microcontroller hardware parameters on the system overall power consumption and thus also on the system lifetime are presented. The influence of the supply voltage, clock frequency and emplacement of the program in the microcontroller memory for MSP430 microcontroller, which is often used nowadays in Wireless Sensor Networks (WSN) nodes, were evaluated. Additionally, we have studied the influence of different power supply systems for the node lifetime and figured out the optimal microcontroller working mode parameters, which allowed to maximize the amount of microcontroller operations for power supply charge using a normal battery and an energy harvesting system based on light energy harvesting. Although the motivation of this article has been the requirements of energy efficient WSN solutions obtained results are as well applicable to any microcontroller based embedded system that is working in harsh energy conditions.

Wireless Sensor Networks in industrial environment: Real-life evaluation results

The paper summarizes the results of the RealFusion project. One of the main objectives of this project was to study the Wireless Sensor Networks (WSN) in real-life industrial environment. The results for the evaluation of different radios utilizing 433 MHz, 868 MHz and 2.4 GHz license-free industrial, scientific and medical (ISM) bands in real-life industrial environment are presented in the paper. Also, the paper discusses the results of development and evaluation of two real-life industrial WSN use cases: the WSN for remote monitoring the amount of bulk substances in the silos of a refractory materials factory and the WSN for remote warehouse monitoring.

Extensible modular wireless sensor and actuator network and IoT platform with plug&play module connection

Efficiency and flexibility are among the key requirements for Wireless Sensor and Actuator Networks (WSAN) of Internet of Things (IoT) era. In this work we present and demonstrate a novel WSAN and IoT platform. The new nodes are constructed by stacking together the different hardware modules encapsulating power sources, processing units, wired and wireless transceivers, sensors and actuators, or sets of those. Once a node is built, its processing unit can automatically identify all the connected hardware modules, obtain required software modules and tune nodes operation accounting for its structure, available resources and active applications.

Energy-efficient routing in wireless sensor networks using power-source type identification

The real-life wireless sensor networks (WSNs) nowadays often include nodes that are powered by various power sources: mains; primary or secondary batteries; or energy harvesting systems, which generate power from the environment. Although information about the parameters of the available power sources for the WSN node is crucial for optimising the operation of the whole network, the contemporary WSN nodes can only estimate the level of their supply voltage at the current time. Therefore, in this paper we are suggesting a simple mechanism that identifies the type of WSN nodes power source based on the measurements of the supply voltage. Based on the suggested power-source type identification (PSTID) mechanism, we introduce and propose the special routing protocol that is intended for WSNs containing nodes that have different power supply sources. The suggested routing protocol allows a significant increase in the lifetime of the whole network compared to the scenarios when no PSTID data is available. The proposed routing protocol is more universal then the existing routing protocols that take into account only the value of the supply voltage.

On feasibility of 5G-grade dedicated RF charging technology for wireless-powered wearables

For decades, wireless energy transfer and harvesting received focused attention in the research community, but with limited practical applications. Recently, with the development of fifth-generation (5G) mobile technology, the concept of dedicated radio-frequency (RF) charging promises to support the growing market of wearable devices. In this work we shed light on the potential of wireless RF power transfer by elaborating upon feasible system parameters and architecture, emphasizing the basic tradeoffs behind omni-directional and directional out-of-band energy transmission, providing system- level performance evaluation, and discussing open challenges on the way to sustainable wireless- powered wearables. The key aspects highlighted in this article include system operation choices, user mobility effects, impact of network and user densities, and regulatory issues. Ultimately, our research aims to facilitate the integration of wireless RF charging technology into the emerging 5G ecosystem.