Добірка наукової літератури з теми "621.396.1"

Актуальність роботи. Зі стрімким розвитком Інтернету речей та популяризацією концепції «розумного міста» кількість підключених до мережі пристроїв з кожним днем невпинно зростає. За прогнозами Ericsson до 2021 р. кількість підключень сягатиме 28 мільярдів. При цьому близько півтора мільярда пристроїв, підключених до глобальної мережі, будуть представляти категорію споживчої електроніки і смарт-автомобілів. Стає очевидним, що звичайних технологій мобільного зв’язку недостатньо для подальшого розвитку IoT мережі через невелику ємність та зону покриття, а також досить високу вартість терміналів. До того ж пристрої можуть знаходитись у важкодоступних місцях, що вимагає їх високої автономності та достатнього рівня сигналу в точці приймання. Це створює потребу впровадження нових технологій безпроводового зв’язку [1]. Для вирішення цієї проблеми була розроблена технологія IoT, яка отримала назву LoRa. Ця технологія, перш за все, відрізняється низьким рівнем енергоспоживання. Її основним призначенням є застосування у М2М додатках. LoRa надає компанії, що працює в сфері телекомунікацій, величезний вибір можливостей. Так, застосування цього стандарту дає змогу значно збільшити дохідності операторів від одного користувача. У цьому випадку, LoRa займе свою нішу в галузі, в якій вимагається мінімальне енергоспоживання та забезпечення безперебійного передавання даних [2]. Мета і завдання дослідження. Метою роботи є дослідження реалізації сенсорної мережі з використанням технологої LoRa. Для досягнення поставленої мети необхідно виконати такі завдання:  розглянути концепцію сенсорних мереж і технології, що використовуються в системах Інтернету речей;  дослідити технічні характеристики технології LoRa;  проаналізувати можливості технології для її використання;  змоделювати мережу покриття частини міста для використання технології LoRa; Об’єкт дослідження - безпроводова телекомунікаційна технологія LoRa. Предмет дослідження – створення сенсорних мереж в рамках ІоТ за технологією LoRa. Методи дослідження – критичний аналіз технології LoRa та інших безпроводових технологій ІоТ, використання програмного забезпечення Atoll для моделювання мережі за технологією LoRa. Наукова новизна одержаних результатів. Удосконалено застосування технології LoRa для створення сенсорних мереж ІоТ, що дає можливість реалізувати такі складові як транспортна, медична, адміністративна, що вимагають мінімальних затримок та невисокої швидкості передачі даних (близько 10 кбіт/с). Практичне значення одержаних результатів. Запропоновано сценарії застосування технології LoRa у великих містах та мегаполісах в Україні на основі вже існуючих стільникових мереж LTE та встановленого обладнання на частоті 900 МГц, що вже використовується операторами. Розраховано параметри мережі та проведено її моделювання в програмному середовищі Atoll на території 4,5 км2 [2]. Практичним результатом роботи є те, що отримано модель покриття сенсорної мережі та здобуто знання про її впровадження в системах Інтернету речей. Результати проведеної роботи можуть бути використані для вибору для проектування сенсорних мереж для Інтернету речей на певній території.
With the rapid development of the Internet of Things and the popularization of the concept of "smart city", the number of devices connected to the network is constantly growing. Ericsson estimates that by 2021 the number of connections will reach 28 billion. At the same time about one and a half billion devices connected to the global network will represent the category of consumer electronics and smart cars. It is becoming clear that conventional mobile technologies are not enough for the further development of the IoT network due to the small capacity and coverage area, as well as the relatively high cost of terminals. In addition, devices may be located in hard-to-reach places, which requires their high autonomy and a sufficient level of signal at the point of reception. This creates the need for new wireless technologies. To solve this problem, IoT technology was developed, which was called LoRa. This technology, above all, has a low level of energy consumption. Its main purpose is to be used in M2M applications. LoRa provides telecommunications companies with a huge range of opportunities. Yes, the application of this standard allows to significantly increase the profitability of operators from one user. In this case, LoRa will occupy its niche in the industry, which requires minimal energy consumption and uninterrupted data transmission.

In recent years, the use of wireless sensor networks has increased. This is due in part to the increasing miniaturization, decreasing costs and the identification of real-world scenarios where sensors can be deployed. Device-free Passive Localisation (DfPL) is the identification of a person without the need for any physical devices i.e. tags or sensors. A DfPL system uses the Received Signal Strength Indicator (RSSI) for monitoring and tracking changes in a Wireless Network infrastructure. The changes in the signal along with prior fingerprinting of a physical location allow identification of a person's location. The human body contains more than 70% water and it is known that resonance frequency of water is 2.4 GHz. Thus the human body reacts as an absorber attenuating the wireless signal. Many of the proposed RSSI-based technologies use the fingerprinting method for estimating the location of the tracked person. Fingerprinting in location estimation systems refers to a method that compares the fingerprint of some characteristic of a signal that is location dependent. This research is focused on implementing DfPL using a Wireless Sensor Network (WSN) to locate the presence of an individual within indoor locations. The main reason for deploying Wireless Sensor Network DfP Localisation is due in part to the benefits of deploying when a wireless network infrastructure is not available. Thus, a novel system that can identify multi-occupants in an environment using patterns of motion from those monitored areas has been deployed. A Pattern Recognition Neural etwork was used to identify two people in the environment. No other work based on the Device-free Passive Localisation (DfPL) technique has focused on multi-occupancy. DfPL is a new approach for detecting a person's presence and estimating the actual position of that person. Various functions such as: tracking, identification, multi-person and automatic construction of a passive radio map could be implemented for DfPL systems. This project is focused on addressing the possibility of deploying a multi-person localisation system based on Wireless Sensor Network DfPL. RSSI-based localisation techniques became more attractive because of their simplicity and robustness in environments affected by multipath compared to the techniques based on metrics like time or angle. The simplicity is achieved due to RSSI-based localisation systems not requiring additional hardware. Further, the RSSI values can be obtained by using functions that are already provided. How- ever, RSSI-based techniques are significantly affected by the variance of the wireless signal.

Optical switches that reflect light through the process of total internal reflection offer many advantages when compared with other systems such as interferometric and resonant devices as compact stl1lctures can be produce~ with a wavelength- and polarizationindependent response. As well as these benefits, they are immune to temperature variations and tolerant to imperfections which can be imparted into a structure from the manufacturing process. To reflect light efficiently requires the creation of an abl1lpt change in refractive index which is difficult to achieve in silicon based material systems operating through carrier injection due to the long diffusion length of caniers. The aim of this project was to design, fabricate and test a canier injection reflective optical switch in the silicon-on-insulator material system for routing applications within a telecommunication network. To achieve the objective, a reflective optical switch design has been developed which consists of a symmetric Y-branch rib waveguide with twinp-i-n diode arrangement. A confinement barrier is incorporated into the structure which is created by the standard CMOS process of creating a deep isolation trench that prevents caniers from diffusing outside the modulation region and at the same time allows the passage of a propagating mode. Computer simulations have predicted the devices are capable of attaining low TE/TM crosstalk values of -20dB for a power consumption below 22.5m W. Models of the ultrathin oxide barrier which is used in the deep isolation trench for electrical isolation have indicated that a layer with a thickness of2nm can achieve the lowest TE/TM losses of 0.05 and 1.77dB, respectively. Prototype devices have been successfully constl1lcted by using equipment typically found in academia cleamoom environments. Processing was undertaken by using techniques such as chemical mechanical polishing and cryogenic reactive ion etching. The ultrathin oxide has been formed in nitric acid for the confmement banier. Testing has demonstrated the prototypes are capable of directing light from an input port to a particular output port by applying a forward bias to one of the modulation regions. 111

IP-based packet-switched networks have become one of the main content distribution platforms for emerging multimedia services such as IPTV, thanks to the rapidly growing bandwidth and exclusive internetworking and interactivity features of IP-based networks. Meanwhile, high quality video content services are becoming particularly popular within content delivery networks (CDN). During content distribution, packets of encoded video streams can be delayed, corrupted or dropped due to network impairments in packet-switched networks. This leads to perceptual quality degradations of the delivered content at receiver. Although network impairments are rare in commercial managed networks, any distortion caused by impairments can be highly detrimental to end users' experience. Consequently the ability to meet customer expectations on video quality has become a critical service differentiator. Quality of Experience (QoE) that was merely recognised as a value-added service of traditional content distribution services is now one of the fundamental requirements and challenges of providing high quality video services. In order to maintain a high level of user experience throughout the life-cycle of a video service, a service quality measurement and management service must be established. In this thesis a parametric assessment model is designed and implemented to provide accurate in-service quality assessment services with respect to human users' perception of visual distortions. The model monitors video quality specifically in response to discrete network impairment events. Multiple impact factors and quantification metrics have been defined for the realisation of assessment functions. Exploiting specifically designed discrete analysis methodology and packet inspection mechanisms, the designed assessment model aims at supporting a quality monitoring service in large scale commercial video content networks. A testbed system, the LA2 system, is also developed to provide an assortment of tools for the design and evaluation of parametric assessment models. Using the LA2 system, comprehensive test plans and subjective experiments are specified and conducted to establish relevant impact factors and to quantitatively model users' opinion of visual distortions as a set of assessment functions. Specifically, the statistical binary logistic model and cumulative logit model are employed to model the distribution of perceivability of content loss distortion in dichotomous and polytomous scales. The designed model provides high performance estimations to subjective user opinions according to selected statistical fitness tests. A validation test also verifies the generality of the designed model

Simulation and performance analysis of wired and wireless Time-Critical Real-Time(TCRT) LANs is the subject of this research work. Special emphasis has been placed on deterministic Medium Access Control (MAC) method as defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.4 Token Passing Bus. Another very popular MAC method based on the IEEE 802.11 wireless LAN standard has also been investigated. The demands imposed by TCRT LANs are of a time-bounded nature which require messages to be delivered on time or within allowable delay defined by the applications they serve. A number of metrics for measuring network performance have been proposed for use throughout the thesis, specific important parameters, such as response time, waiting time, access time, and delay which greatly influence the performance of TCRT LANs have been analysed and examined in great detail. Fine tuning of these parameters was carried out to observe the influence they have on networks performance. Distinct approaches for measuring network performance are proposed and analysed. An analytical approach using mathematical models to determine network performance for different real-time process control applications is analysed and tested. The advantages and limitations of this approach are identified and evaluated for real-time applications. The second approach is modelling by simulation employing industry standards simulation tools, namely Network II.S and COMNET III. These simulation tools provide an effective platform for studying time-critical applications. Simulation models representing process control applications were created. A number of practical simulation models characterising real-time manufacturing cells have been modelled, analysed, and tested. Both simulation tools are used to model different network scenanos utilising the strengths and advantages of each. Simulation results and comparison of specific models were carried out. Network II.S is used to simulate IEEE 802.4 and COMNET III is used to simulate IEEE 802.11. A third approach based on an empirical network is investigated. Real data were collected and fed into a simulationmodel representing this practical network. Results from the simulation models were analysed and compared to evaluate the performance of the practical network and verify the simulation model. This cross-approach concept is found to be a very important way of studying performance of real-time LANs. A number of real-time network applications and scenarios representing process control applications were modelled using the various techniques. A generic network application was modelled to permit a comparison of the three methods. Most of the analyses are modelled using the simulation approach alone. This is due to the complexity and limitations involved in mathematically modelling dynamically changing situations in real-time applications. However, this approach was adopted only after having verified the correctness of the simulation models by cross referencing the results obtained from the mathematical and simulation approaches as applied to the generic (base) model. The simulation models enabled the analysis of the performance of IEEE 802.4 and IEEE 802.11 media access networks protocols used in real-time environments. Hypothetical and actual network scenarios were considered to fully investigate the effects of varying the various parameters on network performance. This research has clearly demonstrated that real-time networks impose different timing restrictions based on the applications they serve. Type of carried traffic by the real-time network plays a major role in influencing the choice of network protocols. Use of wireless network in real-time environment based on IEEE 802.11 under heavy load is ruled out under the current available proposals, however, they could be used in situation under low loading conditions serving small process control and manufacturing cells with limited number of processing elements. On the other hand, Real-time deterministic networks using access protocol based on IEEE 802.4 are found to be suitable for the most demanding network loading conditions and configurations. Simplifying the management functions of the IEEE 802.4 protocol reduces its complexity and costs of deployment without undermining its performance. This in tum will encourage more vendors to adopt the IEEE 802.4 standard for implementation in TCRT applications