378 research outputs found

    Coverage measurements of NB-IoT technology

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    Abstract. The narrowband internet of things (NB-IoT) is a cellular radio access technology that provides seamless connectivity to wireless IoT devices with low latency, low power consumption, and long-range coverage. For long-range coverage, NB-IoT offers a coverage enhancement (CE) mechanism that is achieved by repeating the transmission of signals. Good network coverage is essential to reduce the battery usage and power consumption of IoT devices, while poor network coverage increases the number of repetitions in transmission, which causes high power consumption of IoT devices. The primary objective of this work is to determine the network coverage of NB-IoT technology under the University of Oulu’s 5G test network (5GTN) base station. In this thesis work, measurement results on key performance indicators such as reference signal received power (RSRP), reference signal received quality (RSRQ), received signal strength indicator (RSSI), and signal to noise plus interference (SINR) have been reported. The goal of the measurement is to find out the NB-IoT signal strength at different locations, which are served by the 5GTN cells configured with different parameters, e.g., Tx power levels, antenna tilt angles. The signal strength of NB-IoT technology has been measured at different places under the 5GTN base station in Oulu, Finland. Drive tests have been conducted to measure the signal strength of NB-IoT technology by using the Quectel BG96 module, Qualcomm kDC-5737 dongle and Keysight Nemo Outdoor software. The results have shown the values of RSRP, RSRQ, RSSI, and SINR at different locations within several kilometres of the 5GTN base stations. These values indicate the performance of the network and are used to assess the performance of network services to the end-users. In this work, the overall performance of the network has been checked to verify if network performance meets good signal levels and good network coverage. Relevant details of the NB-IoT technology, the theory behind the signal coverage and comparisons with the measurement results have also been discussed to check the relevance of the measurement results

    Accurate acoustic ranging system using android smartphones

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    ACCURATE ACOUSTIC RANGING SYSTEM USING ANDROID SMARTPHONES By Mohammadbagher Fotouhi, Master of Science A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University Virginia Commonwealth University 2017 Major Director: Dr. Ruixin Niu, Associate Professor of Department of Electrical and Computer Engineering In this thesis, we present the design, implementation, and evaluation of an android ranging system, a high-accuracy acoustic-based ranging system which allows two android mobile phones to learn their physical distance from each other. In this system we propose a practical solution for accurate ranging based on acoustic communication between speakers and microphones on two smartphones. Using the audible-band acoustic signal with the Wi-Fi assistance without the sound disturbance is promising for large deployment. Our method is a pure software-based solution and uses only the most basic set of commodity hardware: a speaker, a microphone, and Wi-Fi communication. So it is readily applicable to many commercial-off-the-shelf mobile devices like cell phones. Our system is the result of several design goals, including user privacy, decentralized administration, and low cost. Rather than relying on any centralized management which tracks the user’s location to help them find their distance, our system helps devices learn their distance from each other without advertising their location information with any centralized management. Compared to alternatives that require special-purpose hardware or pre-existence of precision location infrastructure , our system is applicable on most of off-the-shelf components so it is a commodity-based solution will obviously have wider applications and is cost effective. Currently, two smartphones are used to estimate the distance between them through Wi-Fi and audio communications. The basic idea is estimating the distance between two phones by estimating the traveling time of audio signal from one phone to the other as the speed of sound is known. The preliminary results of ranging demonstrate that our algorithm could achieve high accuracy, and stable and reliable results for real time smartphone-based indoor ranging

    In-field assessment of change-of-direction ability with a single wearable sensor.

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    The Agility T-test is a standardized method to measure the change-of-direction (COD) ability of athletes in the field. It is traditionally scored based on the total completion time, which does not provide information on the different CODs. Augmenting the T-test with wearable sensors provides the opportunity to explore new metrics. Towards this, data of 23 professional soccer players were recorded with a trunk-worn GNSS-IMU (Global Navigation Satellite System-Inertial Measurement Unit) device. A method for detecting the four CODs based on the wavelet-denoised antero-posterior acceleration signal was developed and validated using video data (60 Hz). Following this, completion time was estimated using GNSS ground speed and validated with the photocell data. The proposed method yields an error (mean ± standard deviation) of 0 ± 66 ms for the COD detection, - 0.16 ± 0.22 s for completion time, and a relative error for each COD duration and each sequential movement durations of less than 3.5 ± 16% and 7 ± 7%, respectively. The presented algorithm can highlight the asymmetric performance between the phases and CODs in the right and left direction. By providing a more comprehensive analysis in the field, this work can enable coaches to develop more personalized training and rehabilitation programs

    Open Platforms for Connected Vehicles

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    L'abstract è presente nell'allegato / the abstract is in the attachmen

    Approach to acoustic mapping through continuous mobile monitoring

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    For the production of representative noise maps, a large amount of information is necessary, which includes, among others, on-site measurements of environmental noise. Thus, for noise maps based on measurements, mobile sampling emerges as a possible solution for the enhancement of data acquisition. The present research proposes a complete framework to perform mobile sampling. Since the normative requires long-term values to be presented in a noise map, a sampling strategy based on temporal stratification, which reduces the required sampled days to estimate the annual equivalent noise level, is presented. Furthermore, to compute long-term values for the night period, since they are usually affected by noise sources different to traffic, specifically leisure noise, a complementary temporal and spatial stratification is also presented. Then, the statistical requirements to perform mobile noise measurements using bicycles is evaluated. The vehicles and bicycles journeys are reproduced based on micro-traffic simulation and then coupled with an acoustic modeling. The estimation error of LAeq for the mobile sampling is compared to reference static samples, in terms of the Root Mean Square Error (RMSE), and is computed for different aggregation radius of mobile receivers, and as a function of the number of passes-by and to the distance to its nearest cross street. To perform the mobile sampling on a real scenario, a low-cost noise monitoring device with the aim of performing georeferenced noise sampling, is developed. The accuracy tests suggest that it is able to acquire noise levels with an equivalent accuracy as a Class 2 sound level meter. Finally, to validate the results obtained through the modeling framework, a noise monitoring device is mounted on a bicycle and on-site mobile measurements are performed simultaneously to reference static ones. The same scenario is again recreated based on micro-simulation of traffic complemented with acoustic modeling. Then, for the simulated framework and the on-site measurements, the RMSE of the estimation of LAeq for different aggregation radius of mobile samples is compared to the reference static ones. It is confirmed that mobile sampling is a solution to improve noise data acquisition, which reduces the resources required to produce a noise map without sacrificing the accuracy and representativeness.Para la producción de mapas de ruido representativos, una gran cantidad de información es necesaria, que incluye, entre otras, mediciones de ruido ambiental en sitio. Por lo tanto, para los mapas de ruido basados en mediciones, el muestreo móvil surge como una posible solución para mejorar la adquisición de datos. La presente investigación propone un marco completo para realizar el muestreo móvil. Dado que la normativa requiere de valores de largo plazo para realizar un mapa de ruido, se propone una estrategia de muestreo basada en estratificación temporal que reduce los días de muestreo necesarios para estimar el nivel de ruido equivalente anual. Además, para calcular los valores a largo plazo para el período nocturno, ya que generalmente se ve afectado por fuentes de ruido distintas al tráfico, específicamente de ruido de ocio, se presenta una estratificación temporal y espacial complementaria. Por otra parte, se evalúan los requisitos estadísticos para realizar mediciones de ruido móviles utilizando bicicletas. Los trayectos de los vehículos y las bicicletas se reproducen en base a una microsimulación de tráfico para después combinarse con modelado acústico. El error de estimación del indicador LAeq calculado con el muestreo móvil se compara, en términos del error cuadrático medio (RMSE), con muestras de referencia obtenidas de forma estática para diferentes radios de agregación de receptores móviles, y también en función del número de pases y de la distancia al cruce de calles más cercano. Para realizar el muestreo móvil en un escenario real, se desarrolla un dispositivo de monitoreo de ruido de bajo costo con el objetivo de realizar un muestreo de ruido georreferenciado. Las pruebas de precisión muestran que es capaz de adquirir niveles de ruido con una precisión equivalente a un sonómetro de Clase 2. Finalmente, para validar los resultados obtenidos a través de las simulaciones, se equipa una bicicleta con el dispositivo de monitoreo y se realizan mediciones móviles en sitio al mismo tiempo que mediciones estáticas de referencia. El mismo escenario se recrea basándose nuevamente en una microsimulación de tráfico complementada con modelado acústico. Después, para los niveles de ruido simulados y las mediciones en sitio, el RMSE de la estimación del indicador LAeq para distintos radios de agregación de muestras móviles se compara con el muestreo estático de referencia. Con ello, se confirma que el muestreo móvil es una solución para mejorar la adquisición de datos de ruido, lo que reduce los recursos necesarios para producir un mapa de ruido sin sacrificar la precisión y la representatividad.Postprint (published version

    Collaborative Indoor Positioning Systems: A Systematic Review

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    Research and development in Collaborative Indoor Positioning Systems (CIPSs) is growing steadily due to their potential to improve on the performance of their non-collaborative counterparts. In contrast to the outdoors scenario, where Global Navigation Satellite System is widely adopted, in (collaborative) indoor positioning systems a large variety of technologies, techniques, and methods is being used. Moreover, the diversity of evaluation procedures and scenarios hinders a direct comparison. This paper presents a systematic review that gives a general view of the current CIPSs. A total of 84 works, published between 2006 and 2020, have been identified. These articles were analyzed and classified according to the described system’s architecture, infrastructure, technologies, techniques, methods, and evaluation. The results indicate a growing interest in collaborative positioning, and the trend tend to be towards the use of distributed architectures and infrastructure-less systems. Moreover, the most used technologies to determine the collaborative positioning between users are wireless communication technologies (Wi-Fi, Ultra-WideBand, and Bluetooth). The predominant collaborative positioning techniques are Received Signal Strength Indication, Fingerprinting, and Time of Arrival/Flight, and the collaborative methods are particle filters, Belief Propagation, Extended Kalman Filter, and Least Squares. Simulations are used as the main evaluation procedure. On the basis of the analysis and results, several promising future research avenues and gaps in research were identified

    Indoor Localization Using Radio, Vision and Audio Sensors: Real-Life Data Validation and Discussion

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    This paper investigates indoor localization methods using radio, vision, and audio sensors, respectively, in the same environment. The evaluation is based on state-of-the-art algorithms and uses a real-life dataset. More specifically, we evaluate a machine learning algorithm for radio-based localization with massive MIMO technology, an ORB-SLAM3 algorithm for vision-based localization with an RGB-D camera, and an SFS2 algorithm for audio-based localization with microphone arrays. Aspects including localization accuracy, reliability, calibration requirements, and potential system complexity are discussed to analyze the advantages and limitations of using different sensors for indoor localization tasks. The results can serve as a guideline and basis for further development of robust and high-precision multi-sensory localization systems, e.g., through sensor fusion and context and environment-aware adaptation.Comment: 6 pages, 6 figure

    Võrguaja protokolli serveri arenduse ja toimivuse analüüs

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    Käesolev magistritöö kirjeldab lihtsa võrguaja protokolli (NTP) serveri ehitamist monoplaatarvutisse Tartu Observatooriumi aatomikella tarbeks. See selgitab NTP-protokolli terminoloogiat ja on loodud NTP-serveri ja kliendi jaoks. Mõõtmise eesmärgil kirjeldatakse ka seda, kuidas ehitatatakse NTP-klienti, mis genereerib impulssi sekundis, mis põhineb NTP-kellaajale. Selle kasutamise tulemusi võrreldakse NTP plotteri testitulemustega. Seejärel hinnatakse NTP-serveri eksperimentaalset konfiguratsiooni, millele järgneb arutelu võimalike paranduste ja tulevaste projektide üle.This Master thesis describes the process of building a simple network time protocol (NTP) server on a single-board computer for the Atomic clock at Tartu Observatory. It explains the terminology of NTP protocol and set up for the NTP server. It also describes how to build a NTP client which generates pulse per second by its own script for the measurement purposes. This new pulse is synchronized with the NTP timestamp. Results of its use are compared against the test results from NTP plotter. The experimental configuration of the NTP server is then evaluated which is followed by a discussion regarding possible improvements and future projects
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