Resource Allocation for Machine-Type Communication of Energy-Harvesting Devices in Wi-Fi HaLow Networks
The recent Wi-Fi HaLow technology focuses on adopting Wi-Fi for the needs of the Internet of Things. A key feature of Wi-Fi HaLow is the Restricted Access Window (RAW) mechanism that allows an access point to divide the sensors into groups and to assign each group to an exclusively reserved time interval where only the stations of a particular group can transmit. In this work, we study how to optimally configure RAW in a scenario with a high number of energy harvesting sensor devices. For such a scenario, we consider a problem of device grouping and develop a model of data transmission, which takes into account the peculiarities of channel access and the fact that the devices can run out of energy within the allocated intervals. We show how to use the developed model in order to determine the optimal duration of RAW intervals and the optimal number of groups that provide the required probability of data delivery and minimize the amount of consumed channel resources. The numerical results show that the optimal RAW configuration can reduce the amount of consumed channel resources by almost 50%.
A review and analysis of existing solutions for creating a system for collecting and converting the energy of HF radiation on the Internet of Things is conducted. We propose our development of a system for collecting and converting the energy of HF radiation on the Internet of Things. The result is a proprietary development of a system for collecting and converting high-frequency radiation energy, ready to work at a distance of no more than 0.94 meters from the Wi-Fi router according to the IEEE 802.11 standard. The output voltage in case of continuous operation of our harvester is 3.3 V, which is enough for power supply: temperature sensors with digital output, humidity sensors, and atmospheric pressure sensors. It is possible to achieve an increase in the working distance by increasing the power of the source of electromagnetic waves, to improve the gain of the transmitting and receiving antenna, or to increase the number of receiving antennas.
The development of IoT systems, especially in the field of Industrial Internet of things with a large number of end devices is a complex scientific and technical problem. Inability to take into account the number of factors at the early stage leads to a negative result. This document demonstrates the scientific approach to the creation of the above systems. The IoT protocols, the IoT system architecture and its components are described in this article. The problems arising in the design of IoT systems are described. The basic characteristics of the most common protocols are systematized. The method for solution of the actual scientific and applied problem, allowing to design the IoT system, taking into account various fundamental parameters including the frequency range, bandwidth, data transfer rate, radiated power, range, work intensity, as well as the fundamental constraints, is proposed. As a result of the application of the described method, the optimal IoT protocol can be chosen to build a system, or to determine and optimize the parameters of the proprietary protocol. That makes it possible to build a reliable and scalable IoT system for the solution of the relevant experimental problems.
When combined with error-correction codes reception techniques based on nonparametric hypothesis testing and order statistics provide strong immunity to different types of interference including multiuser interference. That makes communication systems using such reception techniques most appealing candidates for various applications such as Machine-to-Machine (M2M) communications and Internet Of Things (IOT). Unfortunately analytical treatment of communication systems with nonparametric reception remains a cumbersome task. Therefore simulation remains the main tool for the development of such systems. For multiuser systems supporting hundreds of active users and operating in fading channels (e.g. IOT) time spending grows drastically hampering the design process. Thus the development of simplified multiuser channel models is of great interest. In this paper two simplified mathematical models of multiuser interference for the case of a single user nonparametric reception are proposed. The effectiveness of the proposed models is compared by means of modulation. Special attention is paid to the problem of software implementation of the models proposed.
The paper reviewed and analyzed protocols, technologies for transferring and presenting IoT data, developed a model of a heterogeneous IoT network for hard-to-reach areas, proposed a method to improve the efficiency of data transfer in a heterogeneous IoT network. As a result of the work, a model of using the Internet of Things technology (LPWAN) in hard-to-reach areas was developed, information presentation methods were identified that allow solving the problem of collecting information from remote sensors located in the absence of traditional communication channels and a practical check of the results obtained. The paper uses simulation modeling to study the applicability of different methods of presenting information in the case of transmitting IoT data over low-speed satellite communications channels. The method proposed in the paper allowed the use of the Internet of things technology in remote areas using the SBD satellite short message service. The proposed method allowed reducing the volume and number of SBD messages during data transmission via low-speed satellite communication channels, which made it possible to reduce the cost of communication data transmission by 4.82 times.
Wi-Fi HaLow is an adaptation of the widespread Wi-Fi technology for the Internet of Things scenarios. Such scenarios often involve numerous wireless stations connected to a shared channel, and contention for the channel significantly affects the performance in such networks. Wi-Fi HaLow contains numerous solutions aimed at handling the contention between stations, two of which, namely, the Centralized Authentication Control (CAC) and the Distributed Authentication Control (DAC), address the contention reduction during the link set-up process. The link set-up process is special because the access point knows nothing of the connecting stations and its means of control of these stations are very limited. While DAC is self-adaptive, CAC does require an algorithm to dynamically control its parameters. Being just a framework, the Wi-Fi HaLow standard neither specifies such an algorithm nor recommends which protocol, CAC or DAC, is more suitable in a given situation. In this paper, we solve both issues by developing a novel robust close-to-optimal algorithm for CAC and compare CAC and DAC in a vast set of experiments.
Low Power Wide Area Networks (LPWAN) is a new solution for the Internet of Things (IoT). This type of networks already has several specific implementations like LoRa, Sigfox, Weightless, RPMA and others. Due to long wireless range, low power consumption and numerous nodes low speed overlay networks can be organized on top of LPWAN. Small pieces of data like text messages, low-quality photographs, etc. can be sent over these overlays and can be of significant importance for emergency services. When organizing an overlay network over LPWAN it is important to meet the Quality of Service (QoS) requirements present in the base network to prevent malfunction of its services. This paper presents the results of experimental study of QoS metrics measurement in LoRaWAN networks.
EWDTS-2019 explores the novel trends in testing, diagnosis, repair of microelectronic systems, and also cyber security, automotive, IoT, artificial intelligence.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traﬃc is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the ﬁnal node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a ﬁnite-dimensional system of diﬀerential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of diﬀerential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.
Generalized error-locating codes are discussed. An algorithm for calculation of the upper bound of the probability of erroneous decoding for known code parameters and the input error probability is given. Based on this algorithm, an algorithm for selection of the code parameters for a specified design and input and output error probabilities is constructed. The lower bound of the probability of erroneous decoding is given. Examples of the dependence of the probability of erroneous decoding on the input error probability are given and the behavior of the obtained curves is explained.
Event logs collected by modern information and technical systems usually contain enough data for automated process models discovery. A variety of algorithms was developed for process models discovery, conformance checking, log to model alignment, comparison of process models, etc., nevertheless a quick analysis of ad-hoc selected parts of a journal still have not get a full-fledged implementation. This paper describes an ROLAP-based method of multidimensional event logs storage for process mining. The result of the analysis of the journal is visualized as directed graph representing the union of all possible event sequences, ranked by their occurrence probability. Our implementation allows the analyst to discover process models for sublogs defined by ad-hoc selection of criteria and value of occurrence probability
Let G be a semisimple algebraic group whose decomposition into the product of simple components does not contain simple groups of type A, and P⊆G be a parabolic subgroup. Extending the results of Popov , we enumerate all triples (G, P, n) such that (a) there exists an open G-orbit on the multiple flag variety G/P × G/P × . . . × G/P (n factors), (b) the number of G-orbits on the multiple flag variety is finite.
I give the explicit formula for the (set-theoretical) system of Resultants of m+1 homogeneous polynomials in n+1 variables