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Turbo codes play a crucial role in wireless communication systems, and their compiled code structures are key factors affecting the performance of the entire communication system. As a result, the study of turbo compiled code structures has been a focal point for researchers. The iterative decoding of turbo code structures has multiple limitations and large storage resource consumption, leading to poor system anti‐interference ability and a rapid increase in BER. To address these issues, this paper proposes the mimic turbo compiled code structure (MTCCS) for wireless communication systems. MTCCS is based on the DHR idea, incorporating dynamic, heterogeneous, and redundancy characteristics. Dynamicity is achieved through a dynamic scheduling algorithm based on abnormal feedback information. Heterogeneity is achieved through a codec component collection design method based on intrinsic and extrinsic heterogeneity. Redundancy is achieved through a majority voting algorithm. At the beginning of information transmission, MTCCS randomly selects heterogeneous codecs from the heterogeneous codec collection to enter the runtime pool. After the information transmission is complete, the majority voting algorithm is used to adjudicate the multi‐mode output of the codecs, resulting in a relatively accurate decoding outcome. Meanwhile, the dynamic scheduling module calculates the abnormal feedback information of each codec and accordingly dynamically schedules the mimic turbo codecs to replace the abnormal ones. Through the above process, MTCCS realizes the adaptive compilation code and improves the anti‐interference ability of turbo code. Simulation experiments are conducted on MTCCS in both non‐interference and interference scenarios. Simulation experiments show that MTCCS introducing the DHR idea achieves a balance between anti‐interference and decoding performance. It effectively addresses the issue of poor anti‐interference ability in turbo codes, and the decoding performance of MTCCS is superior to that of the previous single conventional turbo codes. [ABSTRACT FROM AUTHOR]

The authors study the energy efficiency (EE) of ambient backscatter communication (AmBC) device‐assisted and reconfigurable intelligent surfaces (RIS)‐assisted non‐orthogonal multiple access (NOMA) downlinks. The authors establish two optimisation problems based on the two collaborative devices (AmBC devices, RIS) with the objective of maximising the EE of the system, taking into account the requirements of power limitation and rate limitation, etc. and also obtain the solutions of two problems by optimising the relevant performance metrics based on the alternating optimisation algorithm. For the backscatter device (BD)‐aided downlink NOMA network, the problem is first decoupled into three subproblems, where the power allocation optimisation subproblem is solved by using the quadratic transformation method and the subgradient algorithm. The maximum EE is obtained by iterating according to the Dinkelbach's algorithm. For the RIS‐aided downlink NOMA network, the power allocation problem is solved by the same method as above and the phase optimisation problem is solved by the successive convex approximation method. Numerical results show that the proposed algorithm can achieve convergence after several iterations, and the EE of systems with BD‐assisted and RIS‐assisted have different levels of sensitivity to different influencing factors. [ABSTRACT FROM AUTHOR]

Abstract The authors study the energy efficiency (EE) of ambient backscatter communication (AmBC) device‐assisted and reconfigurable intelligent surfaces (RIS)‐assisted non‐orthogonal multiple access (NOMA) downlinks. The authors establish two optimisation problems based on the two collaborative devices (AmBC devices, RIS) with the objective of maximising the EE of the system, taking into account the requirements of power limitation and rate limitation, etc. and also obtain the solutions of two problems by optimising the relevant performance metrics based on the alternating optimisation algorithm. For the backscatter device (BD)‐aided downlink NOMA network, the problem is first decoupled into three subproblems, where the power allocation optimisation subproblem is solved by using the quadratic transformation method and the subgradient algorithm. The maximum EE is obtained by iterating according to the Dinkelbach's algorithm. For the RIS‐aided downlink NOMA network, the power allocation problem is solved by the same method as above and the phase optimisation problem is solved by the successive convex approximation method. Numerical results show that the proposed algorithm can achieve convergence after several iterations, and the EE of systems with BD‐assisted and RIS‐assisted have different levels of sensitivity to different influencing factors.

This letter presents experimental angularly resolved measurements and a model framework for characterizing continuous wideband reflection coefficients at sub‐terahertz frequencies between 92 and 110 GHz. Surfaces that appear "smooth" but with internal features comparable to the wavelength have shown to cause frequency selective scattering. An nth‐degree polynomial regression model is employed to quantify non‐linear multi‐path scattering that cannot be described by a best‐fit line, with least‐squares regression applied to find the best‐fitting polynomial and hence the coefficients. The obtained coefficients are then validated against the delay domain statistics of the propagation channel, demonstrating the proposed model's good agreement with measurements and its efficiency in reproducing angle‐dependent reflection coefficients for use in ray‐tracing tools. [ABSTRACT FROM AUTHOR]

The article deals with the design problems of secure information networks. The process of introducing new information technologies into all spheres of social life is unthinkable without solving the issues of information security, which is structured in completely different but interconnected aspects. Modern progress in the field of global networks and multimedia tools has led to the development of numerous methods designed to ensure the safe transmission of information through telecommunications channels and their use for undeclared purposes, methods of synthesis of various information objects and the development of their new mathematical models. The mathematical apparatus used in the field of information security has so far remained rather limited. Until now, there is no single mathematical approach to the analysis and processing of data about information objects, information transmission networks and their design methods. Due to the lack of a single mathematical apparatus, until now there were no methods for conducting an a priori analysis of the properties of these objects, comparing different technologies of the functioning of communication systems, which in general deprived the possibility of a reasonable choice of the technology of the functioning of the communication network or the method of its design. Therefore, it is extremely relevant to ensure the possibility of automated analysis of the state and functioning of protected communication networks, including the analysis of the functioning of the information system as a whole, taking into account the possibility of the emergence of both natural and artificial channels of information leakage and various types of influences, automatic processing of the results of such leakage and influences, choosing the way to restore the network after an attack, as well as to solve the issues of synthesis and design of protection systems of communication information networks with the involvement of modern mathematical apparatus is the creation of a unified mathematical approach to the problem of assessing the state of communication information networks, which would avoid their heterogeneous and poor formalizability by means of a computationally simple analysis of only a certain group of mathematical parameters describing the functioning of protected communication networks. This work is dedicated to solving this urgent problem. [ABSTRACT FROM AUTHOR]

Abstract This letter presents experimental angularly resolved measurements and a model framework for characterizing continuous wideband reflection coefficients at sub‐terahertz frequencies between 92 and 110 GHz. Surfaces that appear “smooth” but with internal features comparable to the wavelength have shown to cause frequency selective scattering. An nth‐degree polynomial regression model is employed to quantify non‐linear multi‐path scattering that cannot be described by a best‐fit line, with least‐squares regression applied to find the best‐fitting polynomial and hence the coefficients. The obtained coefficients are then validated against the delay domain statistics of the propagation channel, demonstrating the proposed model's good agreement with measurements and its efficiency in reproducing angle‐dependent reflection coefficients for use in ray‐tracing tools.

Abstract A power line carrier (PLC) communication characteristics‐based method is proposed for single‐phase‐to‐ground fault location in neutral isolated medium voltage meshed distribution networks in this paper. The carrier signals with a time‐varying frequency and constant amplitude are processed by a set of PLC transmitters and receivers, whose placement is optimized by regarding the power network as an undirected graph. Two signal encoding and decoding algorithms for the PLC terminals are proposed to avoid using expensive timing systems between the terminals. The fault location technique is implemented by comparing the cosine similarity of amplitude attenuation and phase offset between the fault and a feature library. The node corresponding to the maximum cosine similarity of the characteristics between the present fault and the library is selected as the location of the current fault. Only one set of low‐cost PLC communication terminals and the widely available power lines are needed in the fault location system, making this approach highly practical. Numerical simulations using MATLAB/Simulink have been performed to verify the technique's feasibility. The results show that the method can accurately locate faults in neutral isolated medium voltage meshed distribution networks. Besides, the presented approach achieves a high level of accuracy in estimating transition resistance values.

A power line carrier (PLC) communication characteristics‐based method is proposed for single‐phase‐to‐ground fault location in neutral isolated medium voltage meshed distribution networks in this paper. The carrier signals with a time‐varying frequency and constant amplitude are processed by a set of PLC transmitters and receivers, whose placement is optimized by regarding the power network as an undirected graph. Two signal encoding and decoding algorithms for the PLC terminals are proposed to avoid using expensive timing systems between the terminals. The fault location technique is implemented by comparing the cosine similarity of amplitude attenuation and phase offset between the fault and a feature library. The node corresponding to the maximum cosine similarity of the characteristics between the present fault and the library is selected as the location of the current fault. Only one set of low‐cost PLC communication terminals and the widely available power lines are needed in the fault location system, making this approach highly practical. Numerical simulations using MATLAB/Simulink have been performed to verify the technique's feasibility. The results show that the method can accurately locate faults in neutral isolated medium voltage meshed distribution networks. Besides, the presented approach achieves a high level of accuracy in estimating transition resistance values. [ABSTRACT FROM AUTHOR]

Summary: The paper identifies a Wiener system, which is excited by a cyclostationary time series. To estimate the first subsystem's linear dynamic impulse response: this proposed algorithm first kernel‐windows the Wiener system's input measurements, then cross‐correlates with the output time series. To identify the second subsystem's static nonlinearity: this proposed algorithm first estimates the unobservable inter‐block internal signal (consistently in the statistical sense), and then kernel‐windows these estimates with the Wiener system output. This estimator provides the unusual capability to identify non‐invertible nonlinearities. This strategy removes any restrictive requirement for a Gaussian random excitation or a sinusoidal deterministic excitation. This paper further proves the estimator's asymptotic consistency and determines the kernel bandwidth for algorithmic convergence. The proposed algorithm's efficacy is verified in the context of two common applications: a servo mechanical system and a telecommunication channel. [ABSTRACT FROM AUTHOR]

Wireless communication supports various real-world applications, such as aeronautical navigation, satellite and TV broadcasting, wireless LANs, and mobile communications. The inherent characteristics of the electromagnetic spectrum impose constraints on telecommunication channels and their frequency bandwidths within mobile networks. A persistent challenge in these applications is providing high-demand services to mobile users, where frequency assignment problems, also known as channel assignment problems, assume significance. Researchers have developed several modeling approaches to address different facets of this problem, including the management of interfering radio signals, the assessment of available frequencies, and optimization criteria. In this paper, we present improved algorithms for solving the Minimum Span Frequency Assignment Problem in mobile communication systems using the greedy optimization approach known as F/DR. We solved and evaluated twenty well-known benchmark cases to assess the efficacy of our algorithms. Our findings consistently demonstrate that the modified algorithms outperform the F/DR approach with comparable computational complexity. The proposed algorithm notably achieves the following benchmarks: The modified algorithms consistently produce at least one local optimum better than the traditional algorithm in all benchmark tests. In 95% of the benchmarks evaluated, the probability of discovering a local optimum value (calculated by the modified algorithm) that is better than or equal to the one found by the conventional algorithm exceeds 50%. [ABSTRACT FROM AUTHOR]

• Telecommunications infrastructure could promote entrepreneurship in developing countries represented by China, but there is a time lag. • Telecommunications infrastructure has heterogeneous effects on entrepreneurship in geographic location, city scale, and traditional infrastructure development. • Alleviating capital misallocation and labor misallocation are potential transmission channels for telecommunications infrastructure to impact entrepreneurship. As an essential element of the entrepreneurial ecosystem, telecommunications infrastructure could effectively stimulate entrepreneurial activity. Based on prefectural city data from 2003 to 2019, this study constructs a time-varying difference-in-differences model (DID) to identify the impact of telecommunications infrastructure on entrepreneurship by adopting the Broadband China strategy as a quasi-natural experiment. Several heterogeneity analyses are further conducted under different city characteristics. The potential transmission channels from the perspective of resource misallocation are also explored. The results show that telecommunications infrastructure significantly promotes entrepreneurship in China, but there is a time lag effect. The positive impact of telecommunications infrastructure on entrepreneurship is more pronounced in the midwestern regions, small-medium scales, and cities with underdeveloped traditional infrastructure. Alleviating capital and labor misallocation are potential channels for telecommunications infrastructure to promote entrepreneurship. These findings provide evidence for building telecommunications infrastructure rationally to facilitate entrepreneurship and reduce the imbalance of regional entrepreneurship. [ABSTRACT FROM AUTHOR]

A central goal for quantum technologies is to develop platforms for precise and scalable control of individually addressable artificial atoms with efficient optical interfaces. Color centers in silicon, such as the recently-isolated carbon-related G-center, exhibit emission directly into the telecommunications O-band and can leverage the maturity of silicon-on-insulator photonics. We demonstrate the generation, individual addressing, and spectral trimming of G-center artificial atoms in a silicon-on-insulator photonic integrated circuit platform. Focusing on the neutral charge state emission at 1278 nm, we observe waveguide-coupled single photon emission with narrow inhomogeneous distribution with standard deviation of 1.1 nm, excited state lifetime of 8.3 ± 0.7 ns, and no degradation after over a month of operation. In addition, we introduce a technique for optical trimming of spectral transitions up to 300 pm (55 GHz) and local deactivation of single artificial atoms. This non-volatile spectral programming enables alignment of quantum emitters into 25 GHz telecommunication grid channels. Our demonstration opens the path to quantum information processing based on implantable artificial atoms in very large scale integrated photonics. Realising integrated photonic circuits containing isolated telecommunications-wavelength artificial atom single photon emitters is an outstanding challenge in quantum technologies. Here, the authors demonstrate how to embed optically tunable G-centers in silicon-on-insulator integrated circuits. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc networks (VANETs) refer to ad hoc networks where many vehicles and other devices connect to wireless communications and exchange their information. The combination of VANETs in a heterogeneous Internet of Things (IoT) allows vehicles belonging to different cryptosystems to communicate with each other. An essential purpose of the VANET is to implement Vehicle-to-Roadside units (V2R) and Vehicle-to-Vehicle (V2V) communications over a reliable telecommunication channel. Therefore, authentication and privacy are the prime goals of a secure connection. This paper proposes a practical heterogeneous signcryption system for vehicular communication (PHSC-VC) with a pairing free to make V2V communication in VANETs more secure. In PHSC-VC, a vehicle registered in a Certificateless Cryptosystem (CLC) environment can exchange its information with another vehicle registered in a Public-Key Infrastructure (PKI) environment. The recommended protocol meets VANET security requirements such as authentication, unforgeability, confidentiality, and integrity simultaneously at a lower cost. Also, it is effective in high-traffic areas. Besides, under the Computational Diffie-Hellman (CDH) and Discrete logarithm (DL) concerns, the random oracle model reveals that PHSC-VC scheme is secure. Finally, as shown in the performance analysis, our protocol shows lower computation cost, better communication efficiency, and lower power consumption. Hence, PHSC-VC is practical and efficient in achieving cryptography in limited devices such as VANETs. [ABSTRACT FROM AUTHOR]

Non-Orthogonal Multiple Access (NOMA) system has been very interesting technique recommended for the fifth generation (5G) of wireless mobile communication networks. The strategy of a suitable multiple access technique is one of the most important aspects in improving the system capacity. Multiple access techniques can broadly be categorized into two different approaches, namely: OMA and NOMA. In this paper a downlink communication system composed of a base station and M users where each one is equipped with a single antenna is considered, and multiple users system are characterized by multipath communication known as Rayleigh fading channel which can be described by a complex fading channel coefficient. It is well known that NOMA fairness feature implies that, with NOMA approach, near and far mobile users from a base station are able to achieve at least the possible information capacity similarly to OMA users. Fair-NOMA is described by fairness index (F) and a power allocation coefficient (a) limiting the fairness region R bounded by extreme values amin and amax, this fairness index is given as a function of NOMA power allocation coefficient, SNR ratio and channel gains of NOMA users. Maximum fairness index is obtained for a power allocation coefficient belonging to the fairness region, which is large for weak SNR ratios, and slight for high levels. In addition, the calculation of NOMA and OMA ergodic capacities at fairness bounds, indicates that NOMA approach always outperforms OMA one. Further, fairness index evolution is considered in function of channel gains, power allocation coefficients and SNR ratio levels, giving as result, optimal fairness can be reached by a judicious power allocation to the furthest user from the base station. Copyright © 2022 Praise Worthy Prize S.r.l. - All rights reserved. [ABSTRACT FROM AUTHOR]

Call centers are an essential communication channel between telecommunication companies and their customers, playing a pivotal role in creating memorable experiences. Multiple factors influence the satisfaction of Telecommunication customers with their interactions with call centers, so it is essential to measure it. Using a sample of 2236 interactions with call centers from the largest UK Telecom operators, this study aimed to measure the effect of different factors on satisfaction through multiple linear regression. It was observed that the variable with the greatest impact on satisfaction was the resolution of the problem, followed by the will to solve the problem. [ABSTRACT FROM AUTHOR]

We design and evaluate the performance of a one-dimensional photonic crystal (PhC) optical filter that comprises the integration of alternating layers of a barium titanate ferroelectric (BaTiO 3) and an yttrium oxide dielectric (Y 2 O 3) , with a critical high-temperature superconductor defect, yttrium–barium–copper oxide (YBa 2 Cu 3 O 7 − X) , resulting in the (BTO / Y 2 O 3) N / YBCO / (Y 2 O 3 / BTO) N multilayered nanostructure array. Here, we demonstrate that such a nanosystem allows for routing and switching optical signals at well-defined wavelengths, either in the visible or the near-infrared spectral regions—the latter as required in optical telecommunication channels. By tailoring the superconductor layer thickness, the multilayer period number N, the temperature and the direction of incident light, we provide a computational test-bed for the implementation of a PhC-optical filter that works for both wavelength-division multiplexing in the 300–800 nm region and for high-Q filtering in the 1300–1800 nm range. In particular, we show that the filter's quality factor of resonances Q increases with the number of multilayers—it shows an exponential scaling with N (e.g., in the telecom C-band, Q ≈ 470 for N = 8 ). In the telecom region, the light transmission slightly shifts towards longer wavelengths with increasing temperature; this occurs at an average rate of 0.25 nm/K in the range from 20 to 80 K, for N = 5 at normal incidence. This rate can be enhanced, and the filter can thus be used for temperature sensing in the NIR range. Moreover, the filter works at cryogenic temperature environments (e.g., in outer space conditions) and can be integrated into either photonic and optoelectronic circuits or in devices for the transmission of information. [ABSTRACT FROM AUTHOR]

• Presenting an artificial intelligence-based protection method for hybrid parallel HVAC/HVDC overhead transmission lines (HPOTLs) using only the sending-end data (not needing a telecommunication channel) • Using a Decision Tree (DT) algorithm and a fault energy index to select the best features for identification of faulty transmission line (HVAC/HVDC line), type of fault (AC/DC/intersystem fault), and faulty phase(s)/pole(s) • Accurate modeling of HPOTL considering electromagnetic coupling between the HVAC and HVDC lines • Low sampling frequency, high speed and high accuracy in fault detection and classification • Robustness of the proposed method to fault resistance, fault angle, transmission line length and noise In this paper, a novel method is presented to detect and classify the AC, DC, and AC/DC intersystem faults in hybrid parallel HVAC/HVDC overhead transmission lines (HPOTLs) on the same tower. In HPOTLs lines the presence of electromagnetic coupling between the AC and DC conductors induces components in the AC and DC lines which can affect the performance of their protection systems. To tackle these challenges, a protection method based on the decision tree (DT) algorithm and a fault energy index (FEI) is proposed for HPOTLs. The proposed method uses the sending-end voltages and currents of the AC and DC lines and some transformations to calculate the FEIs. The fault detection and classification algorithms and their criteria are derived by the DT algorithm. PSCAD and MATLAB software are used for HPOTL modeling, and voltage and current signals processing, respectively. Simulation results show that the proposed protection method can detect and classify different faults (AC and DC line faults and AC/DC intersystem faults) accurately, and is able to discriminate between transmission line internal and external faults. Simplicity, high speed and accuracy, robustness to the fault resistance and noise, and not needing a telecommunication channel are important features of the proposed method. [ABSTRACT FROM AUTHOR]

Implementation of different telecommunication systems based on wireless optical technologies requires careful awareness of the link conditions in order to predict the performance of each system and its expectations. Wireless optical communication channels, like telecommunication channels, have a fading phenomenon, which is called optical turbulence. A particular class of adaptive networks has the ability to move nodes and can move and converge to moving or static targets. The applications of these networks include dynamic and regional observation and pursuit of underwater military objects. The best type of communication technologies proposed for such networks is Visible Light Communication, or VLC, through which sensors, like the fish schools, with the optical communication between each other, move toward the targets. Investigating the impact of channel conditions and optical noise on these networks are other innovations of this research. In this paper, we model the behavior of a fish school in underwater VLC conditions using a mobile diffusion network. Our simulation results show the effects of water properties on the convergence of the mobile network nodes to a certain target. It is shown that as the water temperature, salinity level and the distance between the nodes increase, the convergence error rises and the nodes become departed from the target position. [ABSTRACT FROM AUTHOR]

Security is one of the most important aspects of data transmission. To provide controlled access to the network, user authorization and authentication are often used with the help of an AAA server. RADIUS servers provide users with access to data, user authentication, and configuration information. When designing networks with such access control method implementation, it is necessary to understand how the characteristics of the communication channel affect the switching time of IP-TV channels, and therefore the overall quality of IPTV services. The principles of the main protocols for IP-TV using a RADIUS server are described. The main parameters of the communication channel were identified. The mathematical model and the graphs demonstrate how IP-TV service access time depends on telecommunication channel parameters. The results of a practical experiment are presented to prove the formed mathematical model. The results of a practical experiment and theoretical calculation are compared. [ABSTRACT FROM AUTHOR]

The paper deals with research into performance of а wideband telecommunication channel with direct spectrum spreading in multipath signal propagation with deployment of adaptive antenna arrays that function according to root mean square error criterion. It is stressed that for root mean square criterion implementation in adaptive arrays, substantial challenge in practical realization is reference signal formation. It is proposed to use for deriving the reference signals wideband signals with direct spectrum spreading that are formed with the help of pseudo noise coding sequences. In using such signals, it is envisioned to deploy RAKE receiver to determine multipath components delays and, in such a way, to obtain reference signals for root mean square criterion. It is stressed that the real wideband signal comprises at least two pseudo noise coding sequences, which spread and scramble the spectrum, and the bit sequence, which transmits the desired signal. Computer simulation of a wideband telecommunication channel is carried out in the conditions of total knowledge of all three components of the wideband signal, two components and only one of them. Computer simulation results allows one to come to the conclusion that lack of knowledge about wideband signal components leads to substantial performance deterioration of adaptive antenna arrays due to impossibility to form the exact reference signal. It is proposed to deploy two approaches to securing adaptive antenna arrays operation in the conditions of incomplete knowledge about the structure of the wideband signal being transmitted in the channel. The first one envisions using discontinued adjustment of adaptive antenna arrays only in the periods of the frame sync pulse transmission, which for the scrambling sequence and the bit sequence of the desired signal always equals unity. The other approach concerns adaptation only in the time intervals with the training sequence transmission, which is known beforehand. It is proposed to carry out further research on studying adaptive performance of adaptive antenna arrays in the discontinuous mode of their adjustment. [ABSTRACT FROM AUTHOR]

The transfer of information by telecommunication channels is accompanied by message hashing to control the integrity of the data and confirm the authenticity of the data. When using a reliable hash function, it is computationally difficult to create a fake message with a pre-existing hash code, however, due to the weaknesses of specific hashing algorithms, this threat can be feasible. To increase the level of cryptographic strength of transmitted messages over telecommunication channels, there are ways to create hash codes, which, according to practical research, are imperfect in terms of the speed of their formation and the degree of cryptographic strength. The collisional properties of hashing functions formed using the modified UMAC algorithm using the methodology for assessing the universality and strict universality of hash codes are investigated. Based on the results of the research, an assessment of the impact of the proposed modifications at the last stage of the generation of authentication codes on the provision of universal hashing properties was presented. The analysis of the advantages and disadvantages that accompany the formation of the hash code by the previously known methods is carried out. The scheme of cascading generation of data integrity and authenticity control codes using the UMAC algorithm on crypto-code constructions has been improved. Schemes of algorithms for checking hash codes were developed to meet the requirements of universality and strict universality. The calculation and analysis of collision search in the set of generated hash codes was carried out according to the requirements of a universal and strictly universal class for creating hash codes. [ABSTRACT FROM AUTHOR]

To increase the recording density of optical discs, analog recording techniques such as the use of orthogonal frequency division multiplexing (OFDM) method has been investigated. In OFDM method, the recording signal is separated into several sub frequency bands. So the readout channel becomes tolerant of the deterioration by disturbances such as defocus and disc skew in optical disc systems. Faster than Nyquist (FTN) signaling is known as the method to increase the transfer rate of OFDM channels in the area of telecommunication. In this paper, a possibility to achieve higher recording density of optical disc systems by applying the FTN is described. The readout signal of FTN-OFDM method was calculated using the optical disc readout and the signal processing models considering the crosstalk from adjacent tracks and FTN applied to a five-channel 64-QAM OFDM system. The calculation results show that the proposed system has a possibility of 1.5 times recording density of the conventional optical disc with a similar tolerance to disturbances. [ABSTRACT FROM AUTHOR]

To enhance the performance and the coverage area of the next‐generation heterogeneous wireless networks (HetNets), smaller cells such as femtocells are deployed. A reasonable resource allocation strategy is crucial for the operation of such systems. In this work, the Nash bargaining solution (NBS), Kalai–Smorodinsky bargaining solution (KSBS), and a proposed bargaining solution, which is the combination of NBS and KSBS, are studied to ensure the efficiency and fairness in the transmission rate allocation among femtocells. The mentioned bargaining solutions are optimised subject to the rate constraints due to the Han–Kobayashi (HK) rate splitting scheme, and a maximum tolerable interference caused by femtocell base stations (FBSs) at the macrocell user equipment. Two methods are used to address the bargaining solutions' optimisations. First, the conventional optimisation‐based method is used for the situations where the channel gains are known, then a reinforcement learning‐based algorithm for a real environment is proposed without being aware of the channel gains. To accelerate the speed of the learning process and to initialise the values of quality functions, the hotbooting technique is used. The bargaining solutions are compared by fairness and efficiency criteria in both methods. Numerical simulations show that the proposed reinforcement learning‐based algorithm achieves the same performance derived from the conventional optimisation method. First, this paper studies the two well‐known Nash and Kalai–Smorodinsky bargaining solutions as the good tools to establish fairness in rate allocation problem among femtocells in a HetNet. Then a new bargaining solution is proposed as the combination of the two bargaining solutions. The fairness and the efficiency of the allocated rates to femtocells as the output of optimisation problems of bargaining solutions are compared via Jain index criterion (as the fairness metric) and inverse price of anarchy criterion (as the efficiency metric). Moreover, the femtocell base stations are allowed to use Han–Kobayashi signalling scheme to send their signals in private and common messages which results in the best‐known achievable rate region. Two methods are used to solve the optimisation problems: the conventional optimisation method and the reinforcement learning‐based method (to formulate a real‐world model with the unknown channel gains). It is shown that the proposed bargaining solution (in both methods) results in fairer rates than Nash and Kalai–Smorodinsky bargaining solutions while all of them are efficient. [ABSTRACT FROM AUTHOR]

A Vehicle to Anything (V2X) packet data is used for a vehicle safety and automated driving applications. It is broadcasted periodically to provide a warning message or share the vehicular sensor's data among vehicles. This paper proposes IEEE 802.11p based dual channel transmission and packet selection method to improve the Packet Detection Rate (PDR) for V2X broadcasting messages. The PDR gain of the proposed scheme over the single channel transmission is given theoretically by the packet error rate of a single radio channel. And the PDR improvement is evaluated by a computer simulation in a highway or urban multipath fading channel. [ABSTRACT FROM AUTHOR]

Owing to the continuous and rapid evolution of telecommunication equipment, the demand for a more efficient and noise-robust detection of Dual-tone multi-frequency (DTMF) signals is conspicuous. In this research article, a novel machine learning based approach to detect DTMF tones perturbed by noise, frequency and time variations by employing the K-Nearest Neighbour (KNN) algorithm is proposed. The features required for training the proposed KNN classifier are extracted using Goertzel's Algorithm employed to estimate the absolute Discrete Fourier Transform (DFT) coefficient values for the fundamental DTMF frequencies with or without their secondary harmonic frequencies. The proposed KNN classifier model is configured in four different manners which differ in being trained with or without augmented data, as well as, with or without inclusion of secondary harmonic frequency DFT coefficient values as features. These models are validated with an unseen test data set created to simulate real-time noise as observed in telecommunication channels. We found that the model which is trained using the augmented dataset and additionally includes the absolute DFT values pertaining to the secondary harmonic frequency values of the eight fundamental DTMF frequencies as the features, achieved the best performance with a macro classification F1 score of 0.980835, a 5-fold stratified cross-validation accuracy of 98.47% and test dataset detection accuracy of 98.1053%. Additionally, the proposed KNN classifier has been compared with existing models to ascertain its superiority and proclaim its state-of-the-art performance. It has proven itself utterly reliable and accurate whilst being relatively lightweight. [ABSTRACT FROM AUTHOR]

This paper presents an exact statistical analysis for the best relay location in a random two‐way relay network whose channels are subject to multi‐slope path loss and Rayleigh fading. In this network, relays are distributed randomly as a two‐dimensional Poisson point process, and the best relay is selected according to a max–min criterion. The midpoint between the two sources is adopted as a reference point and the relays are indexed such that the closer to the reference point, the smaller is the index. An exact analytical expression is derived for the probability that the kth nearest relay to the reference point is the best relay. Then, a detailed statistical analysis for the location of the best relay with respect to the reference point is presented. In each case, a low‐complexity approximation is also derived and its accuracy is verified by numerical simulation. The proposed analysis demonstrates the counter‐intuitive fact that the best relay in a random two‐way relay network is quite unlikely to be located on, or very close to the reference point. Numerical results also suggest that the proposed analysis can be used to restrict the search region for finding the best relay. [ABSTRACT FROM AUTHOR]

In the last two decades, filters based on defected ground structure (DGS) have been employed in various radio frequency systems, and there has been a significant growth in using these structures. In non-tunable filters, a separate unit is used for each telecommunication channel, while the use of tunable filters can reduce the size of multichannel filters. In this paper, tunable filters based on DGS, microstrip and coplanar waveguide (CPW) structures are reviewed. The filters that are designed in this area include either new DGSs or improvements in the previous structures. This paper focuses on tunable filters that have been based on CPW with DGS in the literature since these filters can be easily implemented using CPW lines with coplanar elements realization, no via hole is needed in these filters and radiation loss is less in CPW lines compared to other types of lines. To the best of the author's knowledge, there is currently no review article on the tunable filters based on microstrip and CPW in MEMS technology. This paper can be very useful for starting to work on tunable filters that include DGS. [ABSTRACT FROM AUTHOR]

This paper focuses on high efficiency secret key generation mechanism of physical‐layer communication over fading channels in ubiquitous wireless networks. The secret key rate via traditional physical‐layer approach could be limited when the wireless propagation channels connecting two sensors change slowly. To generate a high‐rate secret key and improve the communication efficiency over quasi‐static block fading channels, a novel multi‐randomness device‐to‐device secret key generation strategy and a cooperative communication mechanism aided by relay nodes are proposed. In the proposed schemes, the legitimate members to send random signals rotationally in every coherent time T are set; thus, two legitimate ubiquitous wireless network members, Alice and Bob, can obtain the potential correlated information by exploiting the randomness and the reciprocity of the wireless propagation channels. Considering the reciprocity of wireless channels is variable while the forward channel gain and backward channel gain are correlated in coherent time, a modified secret key generation scheme is proposed via layered coding with theoretical secret key rates derived. The simulation results show that the proposed scheme outperforms traditional approaches with favourable application prospects in ubiquitous wireless communications networks and internet of things. [ABSTRACT FROM AUTHOR]

In multi‐cell massive multiple‐input multiple‐output (MIMO) cellular networks, pilot contamination (PC) caused by ineluctable pilot reuse severely restricts the system performance in the effectiveness and reliability of transmission. To deal with this problem, an efficient pilot assignment scheme based on fractional pilot reuse and max k‐cut (FPR‐MKC) is therefore proposed in this study. Specifically, first, the measure of susceptibility to interference for each user is designed, and based on this, an innovative boundary is determined for properly selecting the edge users who could employ the unique pilot sequences. Subsequently, the process of allocating reused pilots is innovatively treated as the partition of the vertices of a graph. Building on this idea, an edge‐weighted undirected graph is constructed to present the potential interference intensity among users, and eventually, the max k‐cut (MKC) strategy is executed, which aims to partition centre users into a desired number of mutually exclusive subsets with maximizing the total weight of the edges between the disjoint subsets. Compared with some existing pilot assignment schemes, the proposed FPR‐MKC scheme can adequately mitigate the PC with significantly enhanced quality of service for edge users, which is verified by theoretical analysis and numerical simulation results. [ABSTRACT FROM AUTHOR]

Demands for stable and efficient transmission are increasing due to the ongoing expansion of global wireless data traffic. One of the most promising ways to moderate burden of traffic load and decrease the queuing delay is to design cross‐layer protocols. This paper considers a utility maximization problem for multipath ad hoc wireless networks via joint cross‐layer congestion control, routing and scheduling design. In the formulated utility maximization problem, rate, scheduling and queuing delay constraints are involved under the condition of fixed channels and time varying channels. To solve this utility maximization problem, two scheduling methods are proposed, that is, perfect scheduling and distributed scheduling. In perfect scheduling, all nodes in the network contribute to the scheduling process, while distributed method only takes into account adjacent nodes. For both methods, the global convergence is proved. A comprehensive simulation evaluation is performed which shows that this proposed algorithms outperform existing cross layer protocols in terms of increasing source rate and reducing congestion price. [ABSTRACT FROM AUTHOR]

Ad hoc networks are characterized by ease of setup, low costs, and frequent use in the corporate world. They ensure safety to the user and maintain the confidentiality of the information circulated. They also allow the user to address the cases of communication failure in areas subject to destruction of communication infrastructure. The proposed protocols in the ad hoc networks often build only one path to achieve communication between the nodes, due to the restrictions of battery run out and the movement of the nodes. This connection is often subject to a failure within a certain range. Thus, multiple alternate paths in ad hoc networks use a solution to failing node communications. In addition, when looking at the situation where interference is widespread, each path is preferably somewhat distant from the others. In this paper, we present a simple processing by building multipath routing that do not overlap at the level of an ad hoc network zone, which is achieved through dividing the zone. The evaluation performed by using Network Simulator (nsallinone-3.20) showed that the proposed ad hoc network connection is more efficient than the connection with the traditional methods of constructing multipath routings. [ABSTRACT FROM AUTHOR]

The development of smart grid technologies has resulted in increased interdependence between power and communication systems. Many of the operations in the existing power system rely on a stable and secured communication system. For electrically weak systems and time-critical applications, this reliance can be even greater, where a small degradation in communication performance can degrade system stability. However, despite inter-dependencies between power and communication systems, only a few studies have investigated the impacts of communication system performance on power system dynamics. This study investigates the dependencies of power system dynamics operations on a communication system performance. First, a detailed, dynamic networked microgrid model is developed in the GridLAB-D simulation environment, along with a representative multi-traffic, multi-channel, multi-protocol communication system model, developed in the network simulator (ns-3). Second, a hierarchical engine for large-scale infrastructure co-simulation framework is developed to co-simulate microgrid dynamics, its communication system, and a microgrid control system. The impact of communication system delays on the dynamic stability of networked microgrids is evaluated for the loss of generation using three use-cases. While the example use-cases examine microgrid applications and the impact to resiliency, the framework can be applied to all levels of power system operations.

Intelligent reflecting surfaces have attracted much attention recently as they can manipulate the wireless channel. However, the typical analysis of the downlink system considers the BS‐IRS‐UE link only. Apart from the BS‐IRS‐UE link, the BS‐UE link also exists. In this letter, closed‐form expressions are derived for coverage at the UE considering both these links. Simulations verify the derived expressions, which shed light on the impact of different parameters. Using the closed‐form expression for coverage, an accurate bound is derived for IRS coverage range, that is, the distance beyond which the coverage drops to zero. [ABSTRACT FROM AUTHOR]

Data compression has its own importance in numerous applications, including power systems and several algorithms were developed for managing data associated with the power system. As security is a matter of concern in transferring the compressed information through any communication channel, data encryption can ensure data security. A low computational, microcontroller implementable, asymmetric key encryption algorithm similar to Rivest–Shamir–Adleman algorithm is proposed here for encrypting any ASCII character. As combined differential binary encoding algorithm (C-DBEA) can handle almost all practical data sets and can achieve a moderately high compression ratio (CR), an attempt was made to ensure the security of the compressed data by developing the low computational compressed, encrypted algorithm. A data array is compressed by using C-DBEA in this compressed, encrypted algorithm and is encrypted by using the proposed encryption algorithm. After successful PC-based testing, the algorithm is implemented successfully at the microcontroller level as well. Finally, the compressed, encrypted Data Acquisition System is realised for measuring distribution voltage where compressed, encrypted data transfer occurs between two microcontrollers. High CR is obtained for the less fluctuating voltage profile data of urban areas where the volume of data reduces by >95%. [ABSTRACT FROM AUTHOR]

Ground-based microwave radiometer (MWR) observations of downwelling brightness temperature (푇퐵) are commonly used to estimate the atmospheric attenuation at relative transparent channels for radiopropagation and telecommunication purposes. The atmospheric attenuation is derived from 푇퐵 by inverting the radiative transfer equation with a priori knowledge of the mean radiating temperature (푇푀푅). 푇푀푅 is usually estimated by either time-variant site climatology (e.g., monthly average computed from atmospheric thermodynamical profiles) or condition-variant estimation from surface meteorological sensors. However, information on 푇푀푅 may also be extracted directly from MWR measurements at other channels than those used to estimate atmospheric attenuation. This paper proposes a novel approach to estimate &#119879 푀푅 in clear and cloudy sky from independent MWR profiler measurements. A linear regression algorithm is trained with a simulated dataset obtained by processing one year of radiosonde observations of atmospheric thermodynamic profiles. The algorithm is trained to estimate 푇푀푅 at K-, and V/W-band frequencies (22-31 and 72-82 GHz, respectively) from independent MWR observations at V-band (54-58 GHz). The retrieval coefficients are then applied to a one-year dataset of real V-band observations, and the estimated 푇푀푅 at K- and V/W-band are compared with estimates from nearly collocated and simultaneous radiosondes. The proposed method provides 푇푀푅 estimates in better agreement with radiosondes than a traditional method, with 32-38% improvement depending on frequency. This maps into an expected improvement in atmospheric attenuation of 10-20% for K-band and ~30% for V/W-band channels. [ABSTRACT FROM AUTHOR]

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In telecommunication channel modelling the wavelength is small compared to the physical features of interest, therefore deterministic ray tracing techniques provide solutions that are more efficient, faster and still within time constraints than current numerical full-wave techniques. Solving fundamental Maxwell's equations is at the core of computational electrodynamics and best suited for modelling electrical field interactions with physical objects where characteristic dimensions of a computing domain is on the order of a few wavelengths in size. However, extreme communication speeds, wireless access points closer to the user and smaller pico and femto cells will require increased accuracy in predicting and planning wireless signals, testing the accuracy limits of the ray tracing methods. The increased computing capabilities and the demand for better characterization of communication channels that span smaller geographical areas make numerical full-wave techniques attractive alternative even for larger problems. The paper surveys ways of overcoming excessive time requirements of numerical fullwave techniques while providing acceptable channel modelling accuracy for the smallest radio cells and possibly wider. We identify several research paths that could lead to improved channel modelling, including numerical algorithm adaptations for large-scale problems, alternative finite-difference approaches, such as meshless methods, and dedicated parallel hardware, possibly as a realization of a dataflow machine. [ABSTRACT FROM AUTHOR]

Multi-Agent Systems are susceptible to external disturbances, sensor failures or collapse of communication channel/media. Such failures disconnect the agent network and thereby hamper the consensus of the system. Quick recovery of consensus is vital to continue the normal operation of an agent-based system. However, only limited works in the past have investigated the problem of recovering the consensus of an agent-based system in the event of a failure. This work proposes a novel algorithmic approach to recover the lost consensus, when an agent-based system is subject to the failure of an agent. The main focus of the algorithm is to reconnect the multi-agent network in a way so as to increase the connectivity of the network, post recovery. The proposed algorithm may be applied to both linear and non-linear continuous-time consensus protocols. To verify the efficiency of the proposed algorithm, it has been applied and tested on two multi-agent networks. The results, thus obtained, have been compared with other state-of-the-art recovery algorithms. Finally, it has been established that the proposed algorithm achieves better connectivity and therefore, faster consensus when compared to the other state-of-the-art. [ABSTRACT FROM AUTHOR]

This paper proposes a novel control strategy for the synchronization of network systems. The designed distributed controllers adopt the communication channels to exchange information. The designed controller for each heterogeneous node includes two parts: 1) the reference generator (RG) to copy the dynamics of the leader and 2) adaptive regulator (AR) to achieve synchronization purpose. Under the action of sampled-data control law, outputs of all RGs converge to the output of the leader. The closed-loop system of the leader and all RGs are be equivalently written as the interaction of an operator and a linear time-invariant system. The small gain theorem is utilized to calculate the upper bound of the sampling intervals. Furthermore, the integral quadratic constraints can provide the passivity-type property of the operator and give the less conservative results. Meanwhile, the AR can ensure that nonidentical node tracks its exosystem. Thus, all nonidentical nodes and the leader achieve output synchronization. The proposed control strategy is similar to the separation principle, which includes two steps. Finally, a numerical example is given to demonstrated the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper presents a procedure for the design of a Wide-Area Damping Controller (WADC) towards improving the low-frequency oscillation modes of the power system considering uncertainties in both nominal power system operation condition and time delay on the WADC communication channels. A set of possible operating conditions is linearized around their equilibrium points and used for the construction of the uncertainty model of the system. The lower and upper limits of the time delay are also included in the set. The WADC operation requires remote signals provided by Phasor Measurement Units and highly susceptible to failures or cyber-attacks that may compromise the controller performance. The proposed procedure evaluates in each stage if the resulting controller presents robustness to communication channel permanent failure. Modal analysis and time-domain nonlinear simulations were conducted in the IEEE 68-bus power system. [ABSTRACT FROM AUTHOR]

Commutativity of subsystems (SSs) in cascade connected forms to form larger systems gets worthy to improve noise disturbance, stability, robustness and many other properties in system design. There is a huge amount of work on the subject of commutativity of linear time-varying (LTV) systems and the mentioned improvements; these are referenced in the introduction. In this paper, another benefit of commutativity property is investigated in detail and illustrated by examples. This benefit is the gain of a new and original method for hiding the original (possibly secret) signals when sending them from one local area to another. Switching, pseudo-commutativity, and power-spectrum which are important for communication channels are extensively studied. It is shown that switching used for increasing safeness and slight deformations in commutativity conditions hardly spoil to attain the mentioned benefit. Hence, the paper presents an original and alternative method in cryptology. The results are all validated by illustrative examples and Matlab simulation toolbox Simulink. [ABSTRACT FROM AUTHOR]

Wireless networks of the next generation should optimally adapt themselves to the operating environment in order to meet the requirements of a significantly higher throughput at a lower energy consumption and at increased utilization of radio resources. The current methods used for the radio environment modelling are insufficiently accurate. Older empirical models can no longer be used to model channel spatial and temporal characteristics because of their inadequacy. The widespread deterministic modelling based on geometric optics significantly deviates from the radio frequency diffraction and scattering behavior. On the other hand, the numerical finite-difference techniques based on the Maxwell’s partial differential equations of electrodynamics do provide the required level of details but are limited to rather small computation domains. However, the increasing number of the access points and the associated reduction in the wireless cell reach suggest to use numerical techniques as a viable alternative to the ray optical modelling of the telecommunication channels. The paper reviews the current challenges and approaches to solving the large-scale telecommunication problems by using the numerical finite-difference techniques and proposes to adapt them because of their considerable acceptability. The techniques complemented with the use of hardware accelerators can become an efficient accuracy-improved alternative of the deterministic models. [ABSTRACT FROM AUTHOR]

Hybrid quantum systems are essential for the realization of distributed quantum networks. In particular, piezo-mechanics operating at typical superconducting qubit frequencies features low thermal excitations, and offers an appealing platform to bridge superconducting quantum processors and optical telecommunication channels. However, integrating superconducting and optomechanical elements at cryogenic temperatures with sufficiently strong interactions remains a tremendous challenge. Here, we report an integrated superconducting cavity piezo-optomechanical platform where 10 GHz phonons are resonantly coupled with photons in a superconducting cavity and a nanophotonic cavity at the same time. Taking advantage of the large piezo-mechanical cooperativity (Cem ~7) and the enhanced optomechanical coupling boosted by a pulsed optical pump, we demonstrate coherent interactions at cryogenic temperatures via the observation of efficient microwave-optical photon conversion. This hybrid interface makes a substantial step towards quantum communication at large scale, as well as novel explorations in microwave-optical photon entanglement and quantum sensing mediated by gigahertz phonons. Hybrid quantum systems would allow interfacing superconducting nodes with optical links. Here, the authors demonstrate an integrated platform where 10 GHz phonons are resonantly coupled with photons in a superconducting cavity and a nanophotonic cavity at the same time, allowing efficient mediation of bidirectional microwave-optical conversion. [ABSTRACT FROM AUTHOR]

We present an analysis of dynamic processes for the electromagnetic wave packet passing through the opaque media with quasi-free charges. We consider plasma sheath surrounding the spacecraft as it passes through the dense layers of the atmosphere. In order to provide effective tunneling of the signal to the receiving antenna, the dielectric “resonator” between the surface of the vehicle and plasma is supposed. We discuss the peculiarities of such radio frequency telecommunication channel and analyze in detail tunneling of the wave packet to the resonator and the decay processes for excited oscillations in the resonator. The peculiarities of tunneling through the nonstationary plasma layer are analyzed. [ABSTRACT FROM AUTHOR]

The compressive sensing theory is implemented by means of analog-to-information converter (AIC) that provides a digitized and compressed output $y$ directly from its analog input signal $x$. A reconstruction algorithm, in turn, is needed to obtain a reconstructed signal $\hat {x}$ that estimates $x$ from $y$. This algorithm can be far away from the AIC, linked through a communication channel, and embedded in a remote machine, for instance. In general, $\hat {x}$ is evaluated in order to test the AIC itself and, in consequence, the performance of the reconstruction algorithm affects the test result of the AIC-under-test and, as a result, can invalidate the AIC test at all. Few state-of-the-art works have proposed the test methods that take into account only the AIC output $y$. However, they take into consideration a single-sine test signal to follow the IEEE Standard 1241 for analog-to-digital converter testing. In this paper, two new AIC test methods are introduced in which only the AIC outputs, that is, only the compressed outputs $y$ , are taken in account. In the first one, multisine signals can be applied and, in the second one, four-parameters sine-wave fit methods, as recommended by the IEEE Standard 1241, can be applied. Experimental results were obtained for two different AIC implementations (namely, random demodulator and random modulation preintegrator) and the signal-to-noise and distortion ratio (SINAD) of both was measured directly from the AIC output proving that the proposed AIC test methods are effective. [ABSTRACT FROM AUTHOR]

We demonstrate realization of a time-modulated metasurface in near-infrared frequency regime via integration of conducting oxide layers into plasmonic stripe nanoantennas arranged in a reflectarray configuration. The permittivity of conducting oxide layers is modulated in time through modulation of carrier concentration by applying radio frequency biasing signals which leads to generation of higher order frequency harmonics. We rigorously characterize the electro-optical frequency conversion performance of the metasurface. We then exploit the dispersionless angle-independent phase discontinuities on the wavefront of higher order frequency harmonics to achieve dynamic multi-wavelength multi-beam scanning across S, C, and L telecommunication bands via pixelated control over the modulation phase delay. It is established that such time-modulated metasurfaces can be utilized as reflectarray antennas for active multicasting as well as wavelength and angle multiplexing, thus improving optical communication capacity by providing multiple access and integrating several communication channels into a single antenna platform. The role of modulation waveform in the spectral diversity of harmonics is also explored. Specifically, modulation waveform is optimized to realize unicast and broadcast links. Finally, active beam-scanning performance of the time-modulated conducting oxide metasurface is compared with that of its quasi-static counterpart verifying the enhanced bandwidth as well as suppressed side lobes in the time-modulated platform. [ABSTRACT FROM AUTHOR]