Wireless communications: principle and practice
... This paper is focused on data communication and transmission in a marine environment. More specifically, we want to carry out a path loss (PL) measurement campaign [7] when communication occurs between a sail boat and a buoy. An example of a similar measurement approach is reported in [8], where the authors performed a comprehensive analysis of the propagation that occurs in the marine environment for frequencies in the 5 GHz band. ...
... This brings one to have a replica of the transmitted signal that reaches the receiver antenna A RX , causing interference at the receiver module. These kinds of channels are referred to as two-ray channels, and their behavior has been fully investigated in [7], where a typical channel response is plotted. It is easy to verify how the power decay may exhibit strong valleys when the RF nodes are separated by short distances. ...
... In a more realistic environment, where the channel is a propagation medium with losses, the received power can decay faster than 20 dB for each distance decade. Hence, let us consider the large-scale model for the received power P RX presented in [7] P ...
This paper focuses on the characterization of radio propagation, and data communication in a marine environment. More specifically, we consider signal propagation when three different sub-gigahertz industrial, scientific, and medical (ISM) bands, i.e., 169 MHz, 434 MHz, and 868 MHz, are used. The main focus of the paper is to evaluate the path loss (PL), i.e., the power loss that a propagation radio wave would experience when communication occurs between a sail boat and a buoy. We describe the measurement results obtained performing three different radio power measurement campaigns, at the three different aforementioned ISM sub-gigahertz bands. We also want to correlate the radio propagation quality with the weather conditions present in the measurement areas. The obtained results show that higher distances are achieved by transmitting at lower frequencies, i.e., 169 MHz, and, on average, the propagation is directly dependent from the dew point index.
... de Fresnel-Kirchoff (Rappaport, 2002a). ...
... Una vez hecho esto, la ubicación del receptor simulado se puede mover iterativamente a diferentes ubicaciones en el área de servicio para deducir el contorno de intensidad de la señal El modelo es muy práctico ya que usa bases de datos topográficos y referencia la información de cada elemento de la matriz correspondiente en un punto en un mapa de área de servicio, mientras que el contenido real de cada elemento de la matriz contiene los datos de elevación sobre el nivel del mar, como se muestra en la Figura 4. Estos tipos de modelos digitales de elevación (DEM) están disponibles en el Servicio Geológico de los Estados Unidos (USGS). El perfil del plano lo reconstruye el programa al cuantificar las alturas del área de servicio a lo largo del radial que une el sistema de transmisor y el equipo receptor (Rappaport, 2002a). ...
... El resultado de las rutinas de interpolación al final genera la matriz de distancias desde el receptor y las alturas correspondientes a lo largo del radial. Pero el algoritmo presenta el problema de reducir el cálculo del enlace punto a punto unidimensional, entonces se recurre a la utilización de las técnicas de difracción con borde de cuchillo como se describió anteriormente para calcular la pérdida de trayecto utilizando (Rappaport, 2002a). ...
La intención de este documento es presentar a los ingenieros en formación, personal técnico y de ingeniería encargados de la planeación y mantenimiento de redes, la posibilidad de ejecutar el proceso de medición del espectro con herramientas básicas de hardware y software para facilitar el trabajo en campo. Es importante tener presente que muchos de los contenidos estudiados en la investigación se basan en las recomendaciones UIT-R en donde se especifican cuales son: los procesos, características y parámetros que se deben estimar para un correcto estudio en la propagación de las ondas radioeléctricas a través de los diferentes medios físicos y ambientes de propagación que se necesitan de la correcta gestión y administración del espectro radioeléctrico.
... The received signal strength finds relationship with the path loss through the effective isotropic radiated power (EIRP). The expression that shows this relationship is described by [32] and is shown in equation (12): ...
... The power consumed by the UEs (CMs & CH) when connected to the BS through the CH is defined in equation (32), while the energy expended by the CMs and CH are respectively represented by equations (33), (34) and (35). To analyze power consumptions when CMs transmit/receive data from the BS through the selected CH in the 100m radius of the study area, cluster 2 of figure 5 was utilized. ...
The research proposed a clustering formation approach that ensures that the chosen cluster head (CH) in D2D communication consumes minimal energy and that the cluster members (CMs) are offered good quality of service. In addition, the study investigated various factors influencing power consumptions of User Equipment (UE) in Device to Device (D2D) Communication. Network and geographic data of the UE were collected within 200m diameter (100m radius) around the chosen base station (BS). A term Hardware Sensing Factor (a weighting factor) was formulated from the collected network data. The HSF and the distance between the UE and the base station were utilized as input data to Self Organizing Map (SOM), an unsupervised machine learning algorithm, to form clusters of the UE. A UE with highest value of HSF and minimal distance to the BS is chosen as the Cluster Head (CH) for each cluster. It was shown that the power consumption of the UE increases as the signal attenuation (which depends on distance) increases. In addition, for every transmission/reception between the Cluster Member (CM) and the BS through the CH, the CH consumes about 2.5% more than the CM. Also, in addition to the effects of signal attenuation, the power consumption of the CH is largely dependent on the number of CMs associated with the CH. Furthermore, it is more energy efficient for the CMs to communicate with the CH than communicate with the BS, especially for edge cell UE.
... The study of radio wave characteristics has received research attention since 1901 when Guglielmo Marconi who first transmitted radio over a distance. The propagation environments are categorized as rural area, suburban area, and urban area [2]. Based on the environment where transmission is to be made, obstacles such as building, trees etc. causes reflection, refraction, diffraction, scattering or blockage of the radio wave. ...
... Note: the PL applicable to an urban area has been computed to be [1], [2], [5]: ...
... e.g. [5,15,17,24,28]. Here we use a suitable function of the form ...
... Another continuously differentiable frequency window function is given in [24] as the raised cosine frequency window function Therefore, instead of determining smooth frequency window functions of the form (3.1) by means of interpolation as in Example 3.6, they can also be constructed by convolution, cf. [15]. ...
In this paper, we discuss some numerical realizations of Shannon’s sampling theorem. First we show the poor convergence of classical Shannon sampling sums by presenting sharp upper and lower bounds on the norm of the Shannon sampling operator. In addition, it is known that in the presence of noise in the samples of a bandlimited function, the convergence of Shannon sampling series may even break down completely. To overcome these drawbacks, one can use oversampling and regularization with a convenient window function. Such a window function can be chosen either in frequency domain or in time domain. We especially put emphasis on the comparison of these two approaches in terms of error decay rates. It turns out that the best numerical results are obtained by oversampling and regularization in time domain using a sinh\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sinh $$\end{document}-type window function or a continuous Kaiser–Bessel window function, which results in an interpolating approximation with localized sampling. Several numerical experiments illustrate the theoretical results.
... Of these, empirical methods are the most commonly used due to their simplicity and applicability to any experimental area [10,[25][26][27]. These empirical models are strictly derived from field measurements and rely on path loss prediction [25,26,29]. In this study, seven of these models were examined: Cost-231-Hata [24,25,28,[30][31][32], FSPL [27,30], Egli [26,30], ECC-33 [26,31,33], Ericsson [31,33], and Sui [31,32,34], in addition to the Hata model [24,28,29]. ...
... These empirical models are strictly derived from field measurements and rely on path loss prediction [25,26,29]. In this study, seven of these models were examined: Cost-231-Hata [24,25,28,[30][31][32], FSPL [27,30], Egli [26,30], ECC-33 [26,31,33], Ericsson [31,33], and Sui [31,32,34], in addition to the Hata model [24,28,29]. ...
The precise placement of antennas is essential to ensure effective coverage, service quality, and network capacity in wireless communications, particularly given the exponential growth of mobile connectivity. The antenna positioning problem (APP) has evolved from theoretical approaches to practical solutions employing advanced algorithms, such as evolutionary algorithms. This study focuses on developing innovative web tools harnessing genetic algorithms to optimize antenna positioning, starting from propagation loss calculations. To achieve this, seven empirical models were reviewed and integrated into an antenna positioning web tool. Results demonstrate that, with minimal configuration and careful model selection, a detailed analysis of antenna positioning in any area is feasible. The tool was developed using Java 17 and TypeScript 5.1.6, utilizing the JMetal framework to apply genetic algorithms, and features a React-based web interface facilitating application integration. For future research, consideration is given to implementing a server capable of analyzing the environment based on specific area selection, thereby enhancing the precision and objectivity of antenna positioning analysis.
... Consider a representative value of r in an OFDM system. According to [42]- [44], the coherence time interval within which the channel auto-correlation function is above 0.5 is given by ...
... where Λ k,m Ω k,m + Ψ h k,m ∈ C N ×N , and C is Pearl's normalization constant. From (42), the soft replica of h m [k] and its MSE are respectively expressed aŝ ...
We propose a novel joint channel tracking and data detection (JCTDD) scheme to combat the channel aging phenomenon typical of millimeter-wave (mmWave) multiple-input multiple-output (MIMO) communication systems in high-mobility scenarios. The contribution aims to significantly reduce the communication overhead required to estimate time-varying mmWave channels by leveraging a Bayesian message passing framework based on Gaussian approximation, to jointly perform channel tracking (CT) and data detection (DD). The proposed method can be interpreted as an extension of the Kalman filter-based two-stage tracking mechanism to a Bayesian bilinear inference (BBI)-based joint channel and data estimation (JCDE) framework, featuring the ability to predict future channel state information (CSI) from both reference and payload signals by using an auto-regressive (AR) model describing the time variability of mmWave channel as a state transition model in a bilinear inference algorithm. The resulting JCTDD scheme allows us to track the symbol-by-symbol time variation of channels without embedding additional pilots, leaving any added redundancy to be exploited for channel coding, dramatically improving system performance. The efficacy of the proposed method is confirmed by computer simulations, which show that the proposed method not only significantly outperforms the state-of-the-art (SotA) but also approaches the performance of an idealized Genie-aided scheme.
... In the case of a multipath propagation channel, coherence bandwidth (B c ) is an important parameter to understand the frequency selective nature of the channel. In general B c is calculated from a power delay profile (PDP) Rappaport (2009). As in Rappaport (2009), the PDP can be estimated as given below, ...
... In general B c is calculated from a power delay profile (PDP) Rappaport (2009). As in Rappaport (2009), the PDP can be estimated as given below, ...
... This model reliably describes the effect of the AWGN channel on signal, but it is not suitable for other types of channels. Ref. [12] follows the conventional idea [13] which views the channel model as a time-varying linear system with additive noise. They use a neural network layer and an additive noise layer to implement the channel model. ...
... Updating the neural network weight θ T of the encoder in Transmitter-i by backpropagation. 13: until Stop criterion is met. ...
Deep Joint transmitter-receiver optimized communication system (Deep JTROCS) is a new physical layer communication system. It integrates the functions of various signal processing blocks into deep neural networks in the transmitter and receiver. Therefore, Deep JTROCS can approach the optimal state at the system level by the joint training of these neural networks. However, due to the non-differentiable feature of the channel, the back-propagation of Deep JTROCS training gradients is hindered which hinders the training of the neural networks in the transmitter. Although researchers have proposed methods to train transmitters using auxiliary tools such as channel models or feedback links, these tools are not available in many real-world communication scenarios, limiting the application of Deep JTROCS. In this paper, we propose a new method to use undertrained Deep JTROCS to transmit the training signals and use these signals to reconstruct the training gradient of the neural networks in the transmitter, thus avoiding the use of an additional reliable link. The experimental results show that the proposed method outperforms the additional link-based approach in different tasks and channels. In addition, experiments conducted on real wireless channels validate the practical feasibility of the method.
... The Free Space Path Loss (FSPL) [30] was calculated using the formula: FSPL = 20 log 10 (d) + 20 log 10 (f ) + 20 log 10 4π c ...
The rapid deployment of large-scale UAV-assisted cellular networks has emerged as an effective solution for delivering high-speed data services to ground users in areas where terrestrial base station (BS) infrastructure is inadequate. In this paper, we address a crucial problem in these networks by aiming to maximize the uplink total rate through joint optimization of Unmanned Aerial Vehicle (UAV) association and Orthogonal Frequency Division Multiple Access (OFDMA) subcarrier assignment. However, due to the mobility of pedestrians, fixed association and subcarrier assignments lack adaptation, and centralized optimization does not scale well, especially in large-scale UAV settings. To overcome these challenges, we formulate the joint optimization problem as an exact Constrained Potential Game, called the Subcarrier Assignment and UAV Association Game (SAUAG), based on game theory. In SAUAG, each user selfishness selects the most appropriate strategy with the objective of maximizing their own utility while still fulfilling the system’s Quality of Service (QoS) constraints. We analyze the conditions under which a Nash Equilibrium (NE) exists and provide rigorous proof of its existence.To mitigate the computational complexity typically associated with Best Response Dynamics (BRD), we introduce the Two-Step Better Response (TS-BR) algorithm, which significantly reduces the computational load while ensuring convergence to an NE. Furthermore, we proposed a distributed algorithm based on sequential play and demonstrated its effectiveness in achieving NE convergence. Through comprehensive simulations, the superiority of the proposed SAUAG and TS-BR algorithms was demonstrated, showing their potential in enhancing network performance and adaptability in UAV-assisted OFDMA networks with mobile ground users.
... However, it should be noted that the file does not contain topographic information. Relevant data can be obtained from the United States Geological Survey website [13]. The USGS provides free elevation data for any region on the globe. ...
The paper investigates software solutions to simulate radio waves propagation in urban environment, specifically for the context of the Internet of Things (IoT). The purpose of the study is to provide a comprehensive guide for utilizing the Altair Feko software to obtain a detailed representation of the IoT network, its associated parameters and how they relate to the modeling of electromagnetic fields. It is beneficial to simulate the network during the design stage to obtain valuable data and make necessary adjustments. The key features of a Sigfox or other low power IoT network can be obtained by simulation, enabling an evaluation of the network design prior to its actual implementation. Given the growing demand for IoT devices and networks, researching the optimal design and performance of such networks is of great importance. This underscores the need for continuous exploration of effective methods to achieve efficient design and performance of IoT networks.
... Existem três mecanismos básicos de propagação que influenciam em um sistema de comunicação móvel [Rappaport, 2001]: ...
Uma das principais aplicações existentes em Redes de Sensores Sem Fio (RSSFs) é o monitoramento ambiental, mais particularmente no acompanhamento da fauna existente em locais diversos como florestas, campos, etc. Nesses ambientes de difícil acesso, a manutenção dos sensores fica prejudicada e a restrição de energia torna-se um fator primordial para a vida útil da rede. Como na maioria desses casos os dados não são necessários em tempo real, neste trabalho é proposto e avaliado um novo algoritmo cross-layer, denominado PWAVE, voltado para RSSFs com coleta periódica, onde as transmissões dos dados são feitas através de intervalos predeterminados. Enquanto essas transmissões não são executadas, o sensor permanece coletando as informações do ambiente e seus rádios desligam-se, a fim de reduzir o consumo de energia. Diversos outros desafios aparecem diante deste modo de trabalho como, por exemplo, a sincronização dos relógios, que são prontamente solucionados pelo algoritmo proposto. Os resultados mostram que a solução proposta é eficiente e consegue economizar até 51.2% de energia com 99% na taxa de entrega de dados quando comparado com soluções similares.
... It has been well established that in order to remove the effects of ISI, an equalizer has to be employed at the wireless communication receiver [1]. Two choices are available in this regard: an FIR filter and an IIR filter. ...
Finite Impulse Response (FIR) filter model emulates the Inter Symbol Interference (ISI) in a wireless communication channel. An equalizer, typically an Infinite Impulse Response (IIR) filter, behaves as an inverse filter to the FIR filter to remove the effects of the ISI. IIR filters are generally avoided due to tractability issues, and an FIR filter, with an adaptive signal processing algorithm to minimize the error due to the ISI, is deployed at the receiver. However, the filter is observed to quickly reach a steady state where further iterations do not yield a reduction in the error. This can be attributed to relatively slow variations in the steady state error which prevent further reduction of the errors. This work focuses on converting the low frequency error variations to high frequency variations by the use of multirate signal processing. As such, the steady state error can be damped as well, providing further reduction in the error and an enhanced adaptive filter performance.
... The results are presented in terms of accuracy in metres for 2x2m and 4x4m grid environments with percentages representing the amount of change by adding more passives. The moving test results naturally are worse than static tests as signals experience Doppler effect, multi-path interference, reflections and scatterings [34]. The most obvious observation is that as we increase the number of passive devices, there is a diminishing return. ...
Indoor location and micro-location systems are complicated by the lack of available GPS signals. This gap is being filled by Bluetooth and WiFi, but these systems have difficulty maintaining accuracy when the user is moving. This paper presents the results of an exploration of new features of Bluetooth 5.2, namely, Angle of Arrival and Angle of Departure using a Texas Instrument development board and Antenna Array. The research results are: 1) a novel prediction system for indoor positioning and navigation that performs at an accuracy of 0.23m (static), and 0.30m (moving); 2) a comparison and performance analysis of micro-location algorithms; and 3) an architectural model by which other researchers can extend our work on indoor positioning and navigation.
... (37) Then, the BER for the message stream k of the proposed schemes is given by [44] ...
With the continuous progress of intelligent unmanned cluster technology, Unmanned Aerial Vehicle (UAV) have been widely used in military operations, agriculture, uran management, disater relief and other fields. However, due to the broadcast nature of wireless channels, the problem of secure transmission also needs to be urgently addressed. Since UAV are resource-constrained aerial platform, upper-layer encryption techniques can hardly play an equally effective role in UAV communication networks. In this paper, we consider the power-efficient secure beamforming scheme in multicast directional modulation (MCDM) scenario. In MCDM, all legitimate UAVs are divided into groups, and there may exist eavesdroppers (Eves) wiretapping the confidential message. We aim to address the PHY security problem for MCDM by jointly optimizing the beamforming vector and the AN projection matrix. Specifically, the power-efficient MCDM PHY secure scheme with known/unknown locations of Eves is proposed respectively. The beamforming vector per group is designed to obtain a desired standard modulation constellation at the target UAVs while distorting the received signals at other undesired receivers. Then, the power-efficient AN projection matrix optimization (PEANO) method is calculated to enhance the interference to Eves while reducing AN power consumption. Numerical results show that the proposed scheme can achieve a secure and power-efficient wireless transmission of confidential messages in MCDM.
... Let us denote the received power and reference power in dBm as P r and P 0 , respectively, and represent the effect of fading by X σ , which is assumed to be a zero-mean Gaussian random variable. A propagation model [27,28] relating these quantities can be expressed as ...
In this article, multi-sensor indoor positioning, which is based on fusing tri-laterated position data of the target, is considered. A novel method, which is based on federated Kalman filtering and makes use of the fingerprint data, namely, federated Kalman filter with skipped covariance updating (FKF-SCU) is proposed. The data collected on two test beds are used in comparing the performances of the proposed algorithm and that of the regular federated filter. It is shown that the proposed algorithm provides fault tolerance and quick recovery, whenever signal reception from an access point is interrupted, as well as an improvement of 12.57% on the position accuracy.
... Firstly, as the movement of the finger motion is quite small, the amplitude change in the RF reflected signal caused by finger motion could be very faint, hence it is difficult to identify minor variance among users' biometrics extracted from the limited signal variance. According to the theory of the Fresnel model [24,25], when a user moves his/her hand across the boundaries of Fresnel zones, the CSI of the signal will form a series of peaks and valleys. We regard this variance pattern as a kind of RF signal resolution. ...
Radio frequency (RF) technology has been applied to enable advanced behavioral sensing in human-computer interaction. Due to its device-free sensing capability and wide availability on Internet of Things devices. Enabling finger gesture-based identification with high accuracy can be challenging due to low RF signal resolution and user heterogeneity. In this paper, we propose MeshID, a novel RF-based user identification scheme that enables identification through finger gestures with high accuracy. MeshID significantly improves the sensing sensitivity on RF signal interference, and hence is able to extract subtle individual biometrics through velocity distribution profiling (VDP) features from less-distinct finger motions such as drawing digits in the air. We design an efficient few-shot model retraining framework based on first component reverse module, achieving high model robustness and performance in a complex environment. We conduct comprehensive real-world experiments and the results show that MeshID achieves a user identification accuracy of 95.17% on average in three indoor environments. The results indicate that MeshID outperforms the state-of-the-art in identification performance with less cost.
... In all simulation cases we consider a number of 120 radio channels per cell. This corresponds to the spectrum reutilization scheme factor of N=3, for the 800 MHz band (62 carriers for each uplink/downlink communications direction) [7]. As mentioned above, the channel availability is varied at each IPSAG iteration with a 0.5 probability. ...
The paper is about a new routing protocol suggested for Cognitive Radio Networks (CRN) called Head Cluster IP Spectrum Aware Geographic (HC-IPSAG) and the associated performance. The protocol is an extension of the formerly advanced IPSAG routing protocol, for the case of larger CRNs. Splitting of the CRN domain into clusters is considered here. Each cluster is represented by a head node and the inter-cluster routing is done by using the IPSAG routing concepts within the virtual network created by the cluster head nodes. A CRN simulation model has been developed to study the performance of HC-IPSAG. Our results show that the protocol is performing well in the case of high mobility as well as the performance decreases with the growth of the cluster number.
... We consider the Friis transmission formula [20] for the wireless propagation model where for a transmit power of p t , the received power at distance d is calculated by ...
Wireless data communications are always facing the risk of eavesdropping and interception. Conventional protection solutions which are based on encryption may not always be practical as is the case for wireless IoT networks or may soon become ineffective against quantum computers. In this regard, Physical Layer Security (PLS) presents a promising approach to secure wireless communications through the exploitation of the physical properties of the wireless channel. Cooperative Friendly Jamming (CFJ) is among the PLS techniques that have received attention in recent years. However, finding an optimal transmit power allocation that results in the highest secrecy is a complex problem that becomes more difficult to address as the size of the wireless network increases. In this paper, we propose an optimization approach to achieve CFJ in large Wi-Fi networks by using a Reinforcement Learning Algorithm. Obtained results show that our optimization approach offers better secrecy results and becomes more effective as the network size and the density of Wi-Fi access points increase.
... Any kind of communication system's fundamental goal is to deliver information in such a way that the receiver, which is situated at a specific distance from the sender, is able to correctly decode it [1]. MIMO systems are used to increase wireless communication's dependability and assist in providing error-free transmission [2]. ...
For performance enhancement of wireless communication systems, MIMO systems are used and have become an essential component of modern wireless communication networks. Different types of MIMO systems are used according to the application such as massive MIMO (mMIMO), millimeter wave MIMO (mmWave MIMO), distributed MIMO (D-MIMO), cooperative MIMO such as cognitive radio based MIMO, etc. In this paper, Whale Optimization Algorithm (WOA), a metaheuristic technique is used for solving the optimization problem of performing transmit antenna selection (TAS) i.e., selecting the best set of antennas at transmitter side for an overlay cognitive radio (CR) based hybrid MIMO system. Due to their capacity to intelligently utilise the priceless electromagnetic spectrum, CR communication systems prove to be an effective strategy for current and future wireless communication networks. The Bit Error Rate (BER) versus Signal to Noise Ratio (SNR) graphs show the results of the proposed network.
... Hasil dari perhitungan ini sangat berguna untuk menentukan peletakan zona baru. Hasil perhitungan tersebut dapat divisualisasikan pada peta digital dengan menggunakan bentuk lingkaran sebagai jangkauan sinyal menara dengan radius yang dapat ditentukan dengan menggunakan persamaan sebagai 11 berikut [12]. Radius cakupan menara sangat berguna untuk melakukan penataan menara. ...
DISKOMINFO Kabupaten OKU melakukan pemberian rekomendasi kompetensi menara telekomunikasi. Maka dilakukan perencanaan dan penataan menara telekomunikasi. Namun, hal itu masih dilakukan secara manual berdasarkan visualisasi peta pada buku cetak, sehingga ketika terjadi perubahan harus mencetak ulang buku tersebut, serta harus melakukan perencanaan kembali dengan Microsoft Excel, yang membuat proses menjadi lebih sulit dan lama. Selain itu, belum ada layanan informasi menara secara digital menyebabkan Kurangnya informasi bagi provider menara, sehingga kerangka menara belum tertata dengan tepat. Maka solusi dari permasalahan tersebut adalah membangun sistem yang dapat mengelola data, dapat menyewa menara telekomunikasi dan dapat merencanakan kebutuhan menara bersama selama 5 tahun yang akan datang dengan memperhitungkan jumlah biaya, pengguna layanan seluler, kebutuhan lalu lintas, jumlah BTS dan radius cakupan menara, serta dapat memberikan informasi pengecekan koordinat dengan penerapan metode haversine yang berguna agar kerangka menara baru dapat ditata dengan tepat pada sistem, di mana sistem dibuat berbasiskan situs web dengan perancangan menggunakan metode waterfall. Hasil dari penelitian ini merupakan sebuah aplikasi yang dapat membantu proses perencanaan dan penataan menara baik visual peta, kebutuhan menara, pengecekan koordinat dan sebagainya dilakukan dengan terkomputerisasi. di mana sistem dibuat berbasis website dengan perancangan menggunakan metode waterfall. Hasil dari penelitian ini merupakan sebuah aplikasi yang dapat membantu proses perencanaan dan penataan menara baik visual peta, kebutuhan menara, pengecekan koordinat dan sebagainya dilakukan dengan terkomputerisasi. di mana sistem dibuat berbasis website dengan perancangan menggunakan metode waterfall. Hasil dari penelitian ini merupakan sebuah aplikasi yang dapat membantu proses perencanaan dan penataan menara baik visual peta, kebutuhan menara, pengecekan koordinat dan sebagainya dilakukan dengan terkomputerisasi.
One of the major challenges in designing a wireless indoor–outdoor communication network operating in tunnels and long corridors is to identify the optimal location of the outside station for attaining a proper coverage. It is required to formulate a combined model, describing the propagation along the tunnel and the resulting diffracted outdoor pattern from its exit. An integrated model enables estimations of the radiation patterns at the rectangular tunnel exit, as well as in the free space outside of the tunnel. The tunnel propagation model is based on a ray-tracing image model, while the free-space diffraction model is based on applying the far-field Fraunhofer diffraction equation. The model predictions of sensing the radiation intensity at the tunnel end and at a plane located at a distance ahead were compared with experimental data obtained using a down-scaled tunnel model and shorter radiation wavelength correspondingly. This down-scaling enabled detailed measurements of the radiation patterns at the tunnel exit and at the far field. The experimental measurements for the scaled tunnel case fit the theoretical model predictions. The presented model accurately described the multi-path effects emerging from inside the tunnel and the resulting outdoor diffracted pattern at a distance from the tunnel exit.
In this paper, we propose a geometric channel model for air-to-air (A2A) unmanned aerial vehicle (UAV) communication scenarios. The model is established by incorporating line-of-sight, specular reflection, and diffuse scattering components, and it can capture the impacts of UAV vibrations induced by the propeller’s rotation. Based on UAV heights and ground scatterer density, a closed-form expression is derived to jointly capture the zenith and azimuth angular distributions of diffuse rays. The power of diffuse rays is modeled according to the grazing angle of the rays and the electrical properties and roughness of the ground materials. Key statistics, including the temporal autocorrelation function, spatial cross-correlation function, Doppler power spectrum density, and coherence time are derived, providing an in-depth understanding of the time-variant characteristics of the channel. The results indicate that the presented model is capable of capturing certain A2A channel characteristics, which align with the corresponding theoretical analysis. The findings suggest that the scattering effect of the A2A channel is significantly influenced by the altitude of the UAV. Additionally, it is shown that UAV vibrations can introduce extra Doppler frequencies, notably decreasing the temporal correlation and coherence time of the channel. This effect is more prominent when the system operates at high-frequency bands. The effectiveness of the presented model is confirmed through a comparison of its statistics with those of an existing model and with available measurement data.
This paper introduces CSI-RFF, a new framework that leverages micro-signals embedded within Channel State Information (CSI) curves to realize Radio-Frequency Fingerprinting of commodity off-the-shelf (COTS) WiFi devices for open-set authentication. The micro-signals that serve as RF fingerprints are termed “micro-CSI”. Through experimentation, we have found that the presence of micro-CSI can primarily be attributed to imperfections in the RF circuitry. Furthermore, this characteristic signal is detectable in WiFi 4/5/6 network interface cards (NICs). We have conducted further experiments to determine the most effective CSI collection configurations to stabilize micro-CSI. Yet, extracting micro-CSI for authentication purposes poses a significant challenge. This complexity arises from the fact that CSI measurements inherently include both micro-CSI and the distortions introduced by wireless channels. These two elements are intricately intertwined, making their separation non-trivial. To tackle this challenge, we have developed a signal space-based extraction technique for line-of-sight (LoS) scenarios, which can effectively separate the distortions caused by wireless channels and micro-CSI. Over the course of our comprehensive CSI data collection period extending beyond one year, we found that the extracted micro-CSI displays unique characteristics specific to each WiFi device and remains invariant over time. This establishes micro-CSI as a suitable candidate for device fingerprinting. Finally, we conduct a case study focusing on area access control for mobile robots. In particular, we applied our CSI-RFF framework to identify mobile robots operating in real-world indoor LoS environments based on their transmitted WiFi signals. To accomplish this, we have compared and employed anomaly detection algorithms for the authentication of 15 COTS WiFi 4/5/6 NICs that were carried by a mobile robot under both static and mobile conditions, maintaining an average signal-to-noise ratio (SNR) of 34 dB. Our experimental results demonstrate that the micro-CSI-based authentication algorithm can achieve an average attack detection rate close to 99% with a false alarm rate of 0% in both static and mobile conditions when using 20 CSI measurements to construct one fingerprint.
This chapter serves as an introduction to mobile and fixed wireless access systems. It provides a top-level description of such systems and a brief history of their evolution up to their latest manifestation, namely 5G-Advanced. Finally, several key cellular system coverage methods relevant to 5G deployment are reviewed to help establish the environment that mobile and fixed wireless networks operate in.
In recent years, there has been considerable interest in robust range-based Wireless Sensor Network (WSN) localization due to the increasing importance of accurately locating sensors in various WSN applications. However, achieving precise localization is often hampered by the presence of outliers or underestimations in range measurements, particularly when employing the RSS technique. To tackle these issues, we introduce a Two-Step Localization (namely, the SelMin approach). In the initial phase, the approach utilizes Second-Order Cone Programming (SOCP) to minimize distance discrepancies. It does this by comparing a reference Euclidean Distance Matrix (EDM) with a weighted one derived from imprecise distances between sensor nodes. In the subsequent phase, a heuristic method is employed to identify a specific number of imprecise distances, referred to as outliers, that will be disregarded in the first phase, and this two-phase process continues iteratively. The experimental results demonstrate that the SelMin strategy performs better than the DSCL method when evaluated using the Root Mean Square Error (RMSE) metric. This superior performance is maintained even in challenging conditions, such as when there are many outliers (i.e, around 30 $$\%$$ % ) in the network. This indicates that SelMin is a reliable and robust choice for these environments.
In order to investigate and analyze the behavior of 4G and 5G OFDMA cellular networks in real time, it is essential to have a real‐time testbed to emulate these cellular networks. We developed the experimental testbed in this work and proposed a real‐time approach to emulating these networks. We take real‐time measurements in indoor and outdoor environments. From the results, we say the proposed testbed can be used to identify the activity of spectrum occupancy of 4G and 5G cellular systems within a specified time, and one can also test their algorithm, protocols, and solutions using our developed testbed.
Buku ini adalah panduan komprehensif tentang pentingnya literasi digital di tengah kemajuan teknologi. Mengawali dengan definisi dan urgensi literasi digital, pembaca diperkenalkan pada prinsip-prinsip dasar pengembangannya. Buku ini membahas berbagai topik penting seperti media dan teknologi digital, manajemen informasi, edukasi penggunaan teknologi sesuai hukum, kesehatan digital, perkembangan media sosial, content creator, start-up digital, kecerdasan buatan, Internet of Things, blockchain, dan cryptocurrency. Melalui pembahasan ini, pembaca memperoleh
pemahaman yang mendalam tentang berbagai aspek penting dalam dunia digital.
The presence of green areas in urbanized cities is crucial to reduce the negative impacts of urbanization. However, these areas can influence the signal quality of IoT devices that use wireless communication, such as LoRa technology. Vegetation attenuates electromagnetic waves, interfering with the data transmission between IoT devices, resulting in the need for signal propagation modeling, which considers the effect of vegetation on its propagation. In this context, this research was conducted at the Federal University of Pará, using measurements in a wooded environment composed of the Pau-Mulato species, typical of the Amazon. Two machine learning-based propagation models, GRNN and MLPNN, were developed to consider the effect of Amazonian trees on propagation, analyzing different factors, such as the transmitter’s height relative to the trunk, the beginning of foliage, and the middle of the tree canopy, as well as the LoRa spreading factor (SF) 12, and the co-polarization of the transmitter and receiver antennas. The proposed models demonstrated higher accuracy, achieving values of root mean square error (RMSE) of 3.86 dB and standard deviation (SD) of 3.8614 dB, respectively, compared to existing empirical models like CI, FI, Early ITU-R, COST235, Weissberger, and FITU-R. The significance of this study lies in its potential to boost wireless communications in wooded environments. Furthermore, this research contributes to enhancing more efficient and robust LoRa networks for applications in agriculture, environmental monitoring, and smart urban infrastructure.
This paper addresses the critical gap in the understanding of the effects of various configurations and feedback mechanisms on the performance of hybrid metaheuristics (HMs) in unsupervised clustering applications. Despite the widespread use of HMs due to their ability to leverage multiple optimization methods, the lack of comprehensive studies on their configuration and feedback mechanisms effects often results in sub-optimal clustering performances and premature convergence. To tackle these issues, we introduce two algorithms for implementing eight distinct HM schemes, focusing on the impacts of parallel and serial processing models along with different feedback mechanisms. Our approach involves selecting candidate metaheuristics based on a mix of evolutionary and swarm-based methods, including the k-means algorithm, to form various HM-based clustering schemes. These schemes were then rigorously evaluated across a range of datasets and feedback mechanisms, further assessing their efficiency in the deployment of smart grid base stations. Performance analysis was based on total fitness evaluations, timing capabilities, and clustering accuracy. The results revealed that parallel HMs with decoupled feedback mechanisms performed best in terms of accuracy but at the cost of slower convergence rates as compared to serial HMs. Our findings further suggest that serial HMs will be best suited for time-sensitive applications where a compromise between speed and accuracy is acceptable, while parallel HMs with decoupled feedback mechanisms are preferable for scenarios where precision is paramount. This research significantly contributes to the field by providing a detailed analysis of HM performance in varying conditions, thereby guiding the selection of appropriate HM schemes for specific clustering tasks.
RESUMEN / ABSTRACT Los sistemas de Multiplexación por División de Frecuencias Ortogonales (OFDM), por sus siglas en ingles, han ganado creciente interés debido a su robustez frente a la interferencia provocada por el multitrayecto y a su elevada eficiencia espectral. Cuando se trata de sistemas de altas velocidades de transmisión, empleando mecanismos de corrección FEC sobre canales de comunicación inalámbricos, los esquemas que implementan OFDM constituyen la mejor opción. En el presente trabajo se estudia y caracteriza mediante simulación el rendimiento de estos sistemas cuando se emplea como esquemas de codificación de canal las técnicas de Reed-Solomon y los códigos BCH. Las combinaciones de estos esquemas de codificación externos concatenados con métodos de codificación convolucional internos proporcionan rendimientos desde el punto de la taza de error de bit así como eficiencias energéticas verdaderamente excepcionales a bajos niveles de relaciones señal a ruido. La simulación se lleva a cabo con la ayuda de la herramienta Simulink de Matlab sobre canales de comunicaciones AWGN y canales con desvanecimiento plano y selectivo. En la simulación se hace uso del framework 802.16-2004 que trae incorporado el bloque de comunicaciones de Simulink. Como casos de estudios se incluyen la caracterización de variantes de codificación RS y BCH. Palabras claves: OFDM, Codificación de Canal, Reed-Solomon, BCH, Simulink/Matlab Orthogonal Frequency Division Multiplexing (OFDM) has gained increased interest due to its robustness against multi-path interference and high spectrum efficiency. OFDM is a suitable candidate for high data rate transmission with forward error correction (FEC) methods over wireless channels. In this paper, the system throughput of a working OFDM system is studied and characterized by means of simulation when using channel coding techniques like Reed Solomon and BCH. Combinations of these external coding schemes concatenated with internal convolutional coding provide exceptional error performance and energy efficiency at low signal-to-noise ratio. Simulation of estimated system bit error rate (BER) is performed with the help of Simulink/Matlab tools under the additive white Gaussian noise (AWGN), flat fading and selective fading channel approximation. Characterization of RS and BCH codes is shown as study cases.
In this paper, we tackle the challenging task of reconstructing Received Signal Strength (RSS) maps by harnessing location-dependent radio measurements and augmenting them with supplementary data related to the local environment. This side information includes city plans, terrain elevations, and the locations of gateways. The quantity of available supplementary data varies, necessitating the utilization of Neural Architecture Search (NAS) to tailor the neural network architecture to the specific characteristics of each setting. Our approach takes advantage of NAS’s adaptability, allowing it to automatically explore and pinpoint the optimal neural network architecture for each unique scenario. This adaptability ensures that the model is finely tuned to extract the most relevant features from the input data, thereby maximizing its ability to accurately reconstruct RSS maps. We demonstrate the effectiveness of our approach using three distinct datasets, each corresponding to a major city. Notably, we observe significant enhancements in areas near the gateways, where fluctuations in the mean received signal power are typically more pronounced. This underscores the importance of NAS-driven architectures in capturing subtle spatial variations. We also illustrate how NAS efficiently identifies the architecture of a Neural Network using both labeled and unlabeled data for Radio Map reconstruction. Our findings emphasize the potential of NAS as a potent tool for improving the precision and applicability of RSS map reconstruction techniques in urban environments.
Radio tomographic imaging (RTI) is one of the most favorable device-free localization methods with many advantages. However, since its model is approximate and ill-posed, it has low multi-target localization accuracy in indoor environments. To overcome the problem, we propose an IGWL scheme, the intersection graph of wireless links based multi-target localization, which directly utilizes target-affected links to localize targets. Firstly, the intersections of target-affected links are extracted from all intersections of all wireless links according to the first Fresnel zone. Then, analyze the distribution of extracted intersection graph and determine the intersections with high respect to targets. After, the gap statistic method is used to determine the number of targets. Finally, we modify the K-means algorithm to acquire the locations of targets. The simulation shows that the localization accuracy of the proposed IGWL scheme is significantly higher than the traditional RTI.
Due to its low cost and privacy protection, Channel-State-Information (CSI)-based activity detection has gained interest recently. However, to achieve high accuracy, which is challenging in practice, a significant number of training samples are required. To address the issues of the small sample size and cross-scenario in neural network training, this paper proposes a WiFi human activity-recognition system based on transfer learning using an antenna array: Wi-AR. First, the Intel5300 network card collects CSI signal measurements through an antenna array and processes them with a low-pass filter to reduce noise. Then, a threshold-based sliding window method is applied to extract the signal of independent activities, which is further transformed into time–frequency diagrams. Finally, the produced diagrams are used as input to a pretrained ResNet18 to recognize human activities. The proposed Wi-AR was evaluated using a dataset collected in three different room layouts. The testing results showed that the suggested Wi-AR recognizes human activities with a consistent accuracy of about 94%, outperforming the other conventional convolutional neural network approach.
The integrated fire safety management system incorporates modules that are able to detect, report, monitor, and mitigate fire disasters in the place where it is installed. The system comprises four modules, one to detect the presence of fire, one to investigate the cause of the fire to be a short circuit, one to monitor the condition of the place that can be installed in the user's mobile, and lastly, the fire extinguishing robot that is able to detect the fire and extinguish it locally. The proposed system is able to control that damage to a great extent. This system can be used in schools, office spaces, and hotels where the immediate response to a fire is of utmost importance.
The need for communication with high speed and low latency is not only needed in cellular communication, but also in railway communication. The influence of vehicle speed, such as high-speed train (HST) causes the Doppler effect which can reduce the quality of communication. Selection of the right channel model in the railway communication system, especially for communication on HST is very necessary. This study proposes a Doppler spectrum channel model on HST for DVBT2 (Digital Video Broadcasting-Second Generation Terrestrial) applications using auto correlation validation. The research results show that the line of sight (LOS) condition has a higher channel gain analysis than the Non-LOS (NLOS) condition for the two speed scenarios, and both speeds have a Normal Gaussian pattern based on the PDF analysis. According to the autocorrelation-based channel validation results, both scenarios with speeds of 50 m/s and 100 m/s exhibit a steady slope and no oscillation under LOS conditions. This study also demonstrates that the Doppler shift in the HST channel varies based on the speed scenario and the number of scatterers present, with the higher the frequency and speed resulting in a greater Doppler shift. According to Complementary Cumulative Distribution Function (CCDF) analysis, increasing the HST speed results in a fall in the CCDF value, which also means that the signal power or signal-to-noise ratio (SNR) decreases.
This paper presents a study of an indoor wireless network based on modeling, electromagnetic (EM) simulation, and measurement. It combines Building Information Modeling (BIM) and EM to predict the channel characteristics of an area within the building. Data acquisition is performed to verify the BIM accuracy and to extract channel characteristics.
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