Existing Communication Systems Research Articles

DWT-OFDM forCompressed Image Transmission

All existing communications systems require high-speed data transmission rates, as all services today demand high transmission speeds and data transmission dependability, and communications are an essential aspect of daily life. One of the most important modulation techniques used in both wired and wireless communication networks is Orthogonal Frequency Division Multiplexing (OFDM). It is a cutting-edge technology for achieving high-speed digital communication. In this work, compression Images by Discrete Wavelet Transform and transmission over DWT-OFDM, and used different baseband modulation schemes such as Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Key (QPSK), Quadrature amplitude modulation (16QAM), and (64QAM) has been considered.From numerical simulation results, it is observed that produced better quality images at the receiver when the Quarter Amplitude Modulation is 16QAM and 64QAM with high SNR

Lower boundary capacity estimations of frequency-selective communication channels with PAM-n-signals achievable using resolution time theory

The issue of ensuring high specific capacity of promising wire telecommunication systems is one of the key problems of the last decade. At the same time, despite the existing spectrally efficient modulation methods that are used in existing communication systems, the majority of leading researchers associate further solution of this issue with the transition to the mode of information transmission at a rate "Faster-than-Nyquist" rate (FTN), in which the information receiving about the channel symbol occurs with pronounced intersymbol interference. In turn, this causes difficulties in the practical implementation of the receiver when using optimal signal processing algorithms with nonpolynomial computational complexity, and in the case of suboptimal demodulation methods implementing various types of channel equalization, due to conceptual limitations cannot provide a wide coverage of speeds in this mode. In this regard, the study of an alternative approach to processing signals with multi-position PAM-n-signals on the output of baseband frequency-selective channels (FSC) is relevant. The object of this paper is the study of the possibilities offered by the theory of resolution time for baseband FSC of the, in which information is transmitted using the PAM-n-signal, in the FTN mode. A modified mathematical model of FSC is presented, thanks to which analytical expressions are obtained for estimating the specific capacity in terms of the low bound capacity estimation introduced by Sh. Shamai, expressions for estimating the BER, including the case under the action of destabilizing factors on the symbol synchronization system. Auxiliary capacity estimations and rules for calculating the conditions for achieving them are introduced, convenient for engineering analysis. By means of numerical simulating for the most typical conditions inherent in wired FSC, which are modeled in this work by Chebyshev filters with ripple level of 3 dB and Butterworth filters, it is shown that in the FSN mode with a S/N ratio of no more than 40 dB and instability of the symbol synchronization system operation of 2.5% of the channel symbol duration with a bit error probability of 10–12, it is possible to expect a specific capacity of 5.7–8 bits/Hz*s. It is shown that these results are achieved by using hybrid forms of partial pulses. Recommendations for choosing a partial pulse shape are presented, their main properties are studied from the point of view of their engineering application.

Computational Approach towards Repetitive Design Tasks: The Case Study of Parking Lot Automated Design

The study aims to develop and assess an algorithm for efficiently generating parking spot layouts within predefined area outlines. The algorithm is an attempt to streamline the decision-making process by producing different design variants and optimizing the utilization of available space. The algorithm’s primary objective is to streamline decision-making by generating diverse design variants while optimizing the use of available space, with a distinct focus on mitigating environmental impact and fostering ecological well-being. Researchers conduct thorough tests on the algorithm across various outlines, resulting in multiple layout options for each scenario. They analyzed five representative parking locations and compare the algorithm’s results with the existing parking spot layouts. Throughout the evaluation process, they consider quantitative and qualitative data, considering the complexities of communication solutions within each context. The study findings indicate that the algorithm demonstrates comparable or superior performance to existing solutions. Overall, the study highlights the promising potential of algorithmic design approaches in the context of parking lot automated design. Achieving a balance between innovative designs and user-friendly layouts is crucial, and this is achievable by conducting comprehensive analyses that consider various factors. The consistent findings underscore the algorithm’s potential to significantly contribute to sustainable design practices in parking lot layouts, highlighting decreased environmental strain, efficient land use, and creating urban spaces that prioritize ecological benefits. Furthermore, seamlessly integrating algorithmic solutions with existing communication systems is paramount to ensure practical applicability in real-world scenarios. This integration will enable more effective and practical implementation of the algorithm’s outputs in actual parking lot design projects.

Passive Radar Sensing for Human Activity Recognition: A Survey.

Continuous and unobtrusive monitoring of daily human activities in homes can potentially improve the quality of life and prolong independent living for the elderly and people with chronic diseases by recognizing normal daily activities and detecting gradual changes in their conditions. However, existing human activity recognition (HAR) solutions employ wearable and video-based sensors, which either require dedicated devices to be carried by the user or raise privacy concerns. Radar sensors enable non-intrusive long-term monitoring, while they can exploit existing communication systems, e.g., Wi-Fi, as illuminators of opportunity. This survey provides an overview of passive radar system architectures, signal processing techniques, feature extraction, and machine learning's role in HAR applications. Moreover, it points out challenges in wireless human activity sensing research like robustness, privacy, and multiple user activity sensing and suggests possible future directions, including the coexistence of sensing and communications and the construction of open datasets.

Some Properties of a Discrete Lorenz System Obtained by Variable Midpoint Method and Its Application to Chaotic Signal Modulation

Various discretization effects caused by applying numerical integration techniques to continuous chaotic systems are broadly studied in nonlinear science. Along with the negative impact on the precision of the various finite-difference schemes, such effects may have surprisingly fruitful practical applications, e.g. pseudo-random number generation, image encryption with improved diffusion and confusion properties, chaotic path planning, and many others. One such application is chaos-based communication systems which gained attention in recent decades due to their high covertness and broadband transmission capability. A crucial problem in the design of chaotic communication systems is the modulation of carrier signals. Due to the noise-like properties of chaotic signals, they can barely be modulated using the same methods as conventional harmonic signals. Thus, developing new modulation techniques is of great interest in the field of chaotic communications. In this study, we investigate the discrete model of the Lorenz oscillator obtained using controllable midpoint numerical integration and develop a novel modulation technique for chaos-based communication systems. We discover and analyze the multistability phenomenon in the dynamics of the investigated finite-difference Lorenz model through bifurcation, the basin of attraction, and Lyapunov spectrum analysis procedures. Using a specially designed testbench, we explicitly show that the proposed modulation method outperforms commonly used parametric modulation and is nearly equal to the state-of-the-art symmetry-based modulation in terms of covertness and noise resistivity. In addition, the proposed modulation technique is much easier to implement using computer arithmetics, especially in fixed-point hardware. The reported results may be efficiently applied to designing advanced chaos-based communications systems or improving the characteristics of existing communication system architectures.

Tehnologije koje omogućavaju MTC komunikaciju u domenu vozila

MTC (Machine Type Communications) and the technologies that enable them are at the peak of their development and are gaining increasing significance in the management and control of M2M devices. Since these objects possess intelligence, communication capabilities, and the ability to interact with their environment, they are considered a key component of future smart cities, buildings, vehicles, etc. This paper discusses the technologies that enable MTCs in the domain of vehicles - V2X, the architectures of existing communication systems, as well as the goals and challenges of further development of machine communications in this field.

Performance optimization and parameters estimation for MIMO-OFDM dual-functional communication-radar systems

Dual-function communication radar systems use common Radio Frequency (RF) signals are used for both communication and detection. For better compatibility with existing communication systems, we adopt Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) signals as integrated signals and investigate the estimation performance of MIMO-OFDM signals. First, we analyze the Cramer-Rao Lower Bound (CRLB) of parameter estimation. Then, the transmit powers over different subcarriers are optimized to achieve the best tradeoff between the transmission rate and the estimation performance. Finally, we propose a more accurate estimation method that uses Canonical Polyadic Decomposition (CPD) of the third-order tensor to obtain the parameter matrices. Due to the characteristic of the column structure of the parameter matrices, we only need to use DFT / IDFT to recover the parameters of multiple targets. The simulation results show that tensor-based estimation method can achieve a performance close to CRLB, and the estimation performance can be improved by optimizing the transmit powers.

Graph Neural Networks for Distributed Power Allocation in Wireless Networks: Aggregation Over-the-Air

Distributed power allocation is important for interference-limited wireless networks with dense transceiver pairs. In this paper, we aim to design low signaling overhead distributed power allocation schemes by using graph neural networks (GNNs), which are scalable to the number of wireless links. We first apply the message passing neural network (MPNN), a unified framework of GNN, to solve the problem. We show that the signaling overhead grows quadratically as the network size increases. Inspired from the over-the-air computation (AirComp), we then propose an Air-MPNN framework, where the messages from neighboring nodes are represented by the transmit power of pilots and can be aggregated efficiently by evaluating the total interference power. The signaling overhead of Air-MPNN grows linearly as the network size increases, and we prove that Air-MPNN is permutation invariant. To further reduce the signaling overhead, we propose the Air message passing recurrent neural network (Air-MPRNN), where each node utilizes the graph embedding and local state in the previous frame to update the graph embedding in the current frame. Since existing communication systems send a pilot during each frame, Air-MPRNN can be integrated into the existing standards by adjusting pilot power. Simulation results validate the scalability of the proposed frameworks, and show that they outperform the existing power allocation algorithms in terms of sum-rate for various system parameters.

Toward Zero-Energy Devices: Waveform Design for Low-Power Receivers

The use of a low-power wake-up receiver (WUR) can significantly reduce the device’s energy consumption. To incorporate such WURs into existing communication systems, the waveform design needs to facilitate simple detection yet be compatible with the orthogonal frequency division multiplexing (OFDM) transmission. In this letter, we propose a novel phase design for the wake-up signal (WUS) so that the time-domain distortion of the WUS can be minimized. A majorization-minimization (MM) method is proposed to address the waveform design problem. Simulations show that the proposed scheme can achieve a near-optimal detection performance under different system parameters.

Design of Software Defined Radio (Sdr) Waveforms For Portabilityand Interoperability

The way war is fought depends on the age. The war fighting tactics have been evolving along with the technology innovation. Accordingly, military community is transforming the battlefield of 21st century around Network-Centric Warfare (NCW). As such, the armed forces fight future wars that will be Network-centric. Anything from satellite to soldiers and everything in between whether manned ships, aircraft, ground vehicles, unmanned missiles, sensors and UAVs, secure wireless communications will be the core. The NCW demands voice, video and data capabilities with megabit bandwidths and security so that, seamless sharing of battle field information happens in a timely manner. Hardware intensive radio systems that are currently in use with many armed forces across the globe has limited utility, since parameters for each of the functional modules are fixed. Therefore, existing communication systems is being replaced with digital radio systems called as Software-Defined Radio (SDR). Once deployed, these radios need to be reconfigured periodically to meet the prevailing operational needs. Accordingly, wireless devices and network equipments are reconfigured, enhanced and upgraded through software updates that define the radio functionalities. In military terms it is called as "waveforms". SDR deployed in the battle field vary in size and capability with variety of form factors such as handheld, man pack, airborne, base station, maritime/ ship borne etc. However, the common requirement for all of them is the need to remain in network with portable and interoperable waveforms. It implies that, the waveforms can be used across all platforms with minimal modification with the same baseline architectures while satisfying the specific demands of the application.

Reconfigurable intelligent surface-enabled integrated sensing and communication: a sensing-assisted communication framework

Integrated sensing and communication (ISAC) is an essential technology in the upcoming 6G network, and its performance can be effectively enhanced by the reconfigurable intelligent surface (RIS). Among the various RIS-enabled ISAC techniques, RIS-enabled sensing-assisted communication has attracted growing attention because it can effectively improve communication performance by focusing the energy on the sensed locations of the users and is easy to be integrated into existing communication systems. However, existing RIS-enabled sensing-assisted communication systems rely on antenna arrays for the acquisition of angular information to localize the users, making the system more complex and expensive. To handle this problem, in this paper, we propose an RIS-enabled multi-user sensing-assisted communication framework where a single antenna access point (AP) first senses the locations of the single-antenna users with the help of the RIS, and then the energy of the communication signal is focused on the sensed locations of the users to provide them with a higher sum-rate by adjusting the phase shifts of the RIS. However, the selection of the RIS phase shifts heavily influences the resource block and power allocation at the AP, which makes the joint design of the RIS phase shifts and the resource allocation very challenging. In order to address this challenge, we formulate an RIS-enabled multi-user communication optimization problem and design a two-stage optimization algorithm based on the genetic and Lagrangian duality methods to jointly optimize the RIS phase shifts and the resource allocation. Simulation and experimental results show that compared with the scheme without RIS, the proposed RIS-enabled multi-user communication system can achieve a higher sum-rate and lower localization error.

Exploring barriers and opportunities to improve osteoporosis care across the acute-to-primary care interface: a qualitative study

SummaryThis qualitative study interviewed general practitioners, patients, and FLS clinicians and identified key challenges facing stakeholders seeking to improve post-fracture osteoporosis care. Local policies and care pathways as an initial strategy may address information and service delivery issues across the acute-primary care divide.IntroductionFracture liaison services (FLS) can be effective for secondary fracture prevention, but long-term adherence to therapies remains suboptimal. Few studies have explored how services manage the transition between tertiary and primary post-fracture care. This study mapped service processes and factors influencing integration of post-clinic care, identifying barriers, supports, and opportunities for seamless healthcare.MethodsQualitative descriptive study using semi-structured interviews with FLS stakeholders at two metropolitan hospitals in New South Wales (NSW) and surrounding general practices.ResultsSeven FLS clinicians, 11 general practitioners (GPs), and seven patients were interviewed. Six key themes emerged on the transition of patient care from tertiary to primary care (PC). Interprofessional communication issues and role ambiguity posed threats to seamless care. Delayed, absent, inaccessible, or poor-quality communication frustrated GPs, while FLS clinicians lacked confidence in existing communication systems and desired bidirectional communication with PC. GPs were confident managing osteoporosis, but FLS clinicians had limited confidence that patients would discuss osteoporosis with their GP and that GPs would action recommendations. Effective PC follow-up required a positive GP–patient relationship and that patients perceived a need to engage with PC. Patient understanding of osteoporosis (influenced by patient education, knowledge, beliefs, and health behaviours) affected PC attendance. Limited public awareness of osteoporosis and healthcare policy deficits contributed to care gaps.ConclusionKey challenges were identified facing stakeholders seeking to improving post-clinic osteoporosis care. Development and implementation of local, integrated acute-community policies and care pathways as an initial intervention may address information and service delivery issues across the acute-PC divide.

Factors Influencing Effective Communication between Stakeholder Groups during DVM Work-Based Learning Program in Bangladesh.

This study aimed to review the existing communication systems between the universities, placement providers, and students during the DVM final year work-based learning (WBL) program in Bangladesh. The intention was to identify what factors impact the effectiveness of the communication system and to explore ways to enhance communication to better support the program. A questionnaire was used to collect details about the WBL program and the communication systems from all universities in Bangladesh. The questionnaire was completed on paper at a meeting of the National Veterinary Dean Council and online with a member of each university's WBL coordination team. A summary of the current WBL programs in Bangladesh was produced. Focus group discussions were used to collect more detailed information about the communication systems and were held via Zoom with recent graduates (n = 16) and placement providers (n = 7). Effective means of communication between all stakeholders were identified as an initial letter, phone calls, and spot visits by teachers. However, the frequency of formal communication before and during placements was variable and the ways of providing feedback on the communication systems were insufficient. These issues sometimes undermined the student learning experience. Suggestions for improvements included increased resourcing, greater use of online communication systems, and a national committee to oversee WBL. Other ways to motivate placement providers included a better honorarium and continuing education courses. The results suggest that existing communication systems for veterinary WBL in Bangladesh are not completely satisfactory. Measures are needed to improve communication to optimize the student learning experience and capitalize on the many benefits of the WBL program for all stakeholders.

Speech Communication System Based on Piezoelectric Electret Mechanical Antenna

Low-frequency electromagnetic waves have strong penetration and low attenuation performance, making them widely used in long-wave communication areas such as underwater communication and earthquake prediction. Mechanical antennas are seen as a promising alternative to traditional low-frequency resonant antennas, as they offer the potential for miniaturization and low power consumption. However, existing communication systems using mechanical antennas are usually rudimentary, incompatible, and inconvenient to use. To address these problems, a novel speech communication system based on a piezoelectric electret mechanical antenna was proposed. This communication system includes a hardware system, a communication protocol for mechanical antennas, and a software system with a modular structure. This system includes hardware, a communication protocol, and a modular software system. The results of the experiments showed that this communication system provides real-time speech communication with a user-friendly design, high compatibility with different communication devices, and easy customization to meet specific requirements. This design holds great potential for applications in mineral detection, seismic research, submarine communication, industrial RF control, and other related mechanical antenna applications.

Adaptive Protection for Active Distribution Networks: An Approach Based on Fuses and Relays With Multiple Setting Groups

Protection schemes are essential in active distribution networks and microgrids’ reliable, efficient, and flexible operation. However, the protection of these networks presents significant challenges due to operational changes, such as variations in topology, distributed energy resources connection/disconnection, and microgrid operating modes, among others. This paper proposes an adaptive protection scheme based on overcurrent devices with several setting groups based on artificial intelligence algorithms. The developed strategy is composed of two stages. In the off-line stage, a clustering technique is employed to group the active distribution network operating scenarios exhibiting similarities. The optimal settings for the protection devices are determined for each set of scenarios. On the other hand, in the on-line stage, the protection strategy’s implementation and operation, considering the active distribution network’s existing communication system, are defined. Furthermore, the approach formulates the overcurrent relay coordination as a mixed-integer non-linear optimization problem, and as a result, the optimal setting of the overcurrent protection devices is obtained. It aims to minimize the operating time, considering the transformers’ thermal limits, fuse operating curves, and overcurrent relay settings. The solution is determined by using an Augmented Lagrangian genetic algorithm. The presented protection scheme is validated on the modified IEEE 34 node test feeder, considering the main operating scenarios of the active distribution networks, such as topology changes, distributed energy resource connection/disconnection, and microgrid operating modes (on-grid and off-grid). The results obtained and its easy implementation indicates the high potential for real-life applications.

Millimeter-Waves to Terahertz SISO and MIMO Continuous Variable Quantum Key Distribution

With the exponentially increased demands for large bandwidth, it is important to think about the best network platform as well as the security and privacy of the information in communication networks. Millimetre (mm)-waves and terahertz (THz) with high carrier frequency are proposed as the enabling technologies to overcome Shannon's channel capacity limit of existing communication systems by providing ultrawide bandwidth signals. Mm-waves and THz are also able to build wireless links compatible with optical communication systems. However, most solid-state components that can operate reasonably efficiently at these frequency ranges (100GHz-10THz), especially sources and detectors, require cryogenic cooling, as is a requirement for most quantum systems. Here, we show that secure mm-waves and THz QKD can be achieved when the sources and detectors operate at cryogenic temperatures down to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> = 4K. We compare single-input single-output (SISO) and multiple-input multiple-output (MIMO) Continuous Variable THz Quantum Key Distribution (CVQKD) schemes and find the positive secret key rate in the frequency ranges between <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> =100 GHz and 1 THz. Moreover, we find that the maximum transmission distance could be extended, the secret key rate could be improved in lower temperatures, and achieve a maximum secrete communication distance of more than 5km at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> =100GHz and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> =4K by using 1024×1024 antennas. Our results for the first time show the possibility of mm-waves and THz MIMO CVQKD with the system operating at temperatures below <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> = 50K, which may contribute to the efforts to develop next-generation secure wireless communication systems and quantum internet for applications from inter-satellite and deep space to indoor and short-distance communications.

Modulation and coding scheme in SCMA communication system

Communication networks of future generations should provide a high level of spectral efficiency. The multiple access method is one of the technologies that directly affect this parameter. During the discussion of fifth-generation communication networks, a new approach to designing the non-orthogonal multiple access was proposed. One of the implementation techniques of this approach is sparse code multiple access. In the article, we consider this method and propose an approach to the development of a modulation code scheme to evaluate the sparse code multiple access performance and efficiency under transmission conditions close to reality. The approach is based on a similar modulation code scheme of existing communication systems. To form sparse code multiple access symbols, a codebook based on the mother constellation rotation and interleaving method is considered. We also introduce a modulation code scheme table for SCMA communication systems and evaluate their spectral efficiency.

An intelligent communication system for collision avoidance on roads: A smart city application

Intelligent communication systems have become the predominant paradigm in vehicular ad hoc networks. Current research in this area is limited to the dissemination of emergency information to vehicles after an accident. However, such emergency situations necessitate prompt dissemination of information to the relevant parties prior to the collision save lives. This paper proposes an intelligent collision avoidance routing technique for VANETs (CARVNET) to address this formidable obstacle. The proposed intelligent communication system aims to avoid collisions on roads by disseminating emergency warning messages instantly to the concerned entities as soon as it detects a driver’s abnormal health condition. Simulation studies are conducted in NETSIM to validate the proposed technique. The experimental results demonstrate that the proposed system outperforms existing communication systems by improving throughput by up to 50%, packet transmission by 20%, packet delivery ratio by 10%, and delay to a negligible degree.

Safety Monitoring System of CAVs Considering the Trade-Off between Sampling Interval and Data Reliability.

The safety of urban transportation systems is considered a public health issue worldwide, and many researchers have contributed to improving it. Connected automated vehicles (CAVs) and cooperative intelligent transportation systems (C-ITSs) are considered solutions to ensure the safety of urban transportation systems using various sensors and communication devices. However, realizing a data flow framework, including data collection, data transmission, and data processing, in South Korea is challenging, as CAVs produce a massive amount of data every minute, which cannot be transmitted via existing communication networks. Thus, raw data must be sampled and transmitted to the server for further processing. The data acquired must be highly accurate to ensure the safety of the different agents in C-ITS. On the other hand, raw data must be reduced through sampling to ensure transmission using existing communication systems. Thus, in this study, C-ITS architecture and data flow are designed, including messages and protocols for the safety monitoring system of CAVs, and the optimal sampling interval determined for data transmission while considering the trade-off between communication efficiency and accuracy of the safety performance indicators. Three safety performance indicators were introduced: severe deceleration, lateral position variance, and inverse time to collision. A field test was conducted to collect data from various sensors installed in the CAV, determining the optimal sampling interval. In addition, the Kolmogorov–Smirnov test was conducted to ensure statistical consistency between the sampled and raw datasets. The effects of the sampling interval on message delay, data accuracy, and communication efficiency in terms of the data compression ratio were analyzed. Consequently, a sampling interval of 0.2 s is recommended for optimizing the system’s overall efficiency.

Interference Management with Reflective In-Band Full-Duplex NOMA for Secure 6G Wireless Communication Systems.

The electromagnetic spectrum is used as a medium for modern wireless communication. Most of the spectrum is being utilized by the existing communication system. For technological breakthroughs and fulfilling the demands of better utilization of such natural resources, a novel Reflective In-Band Full-Duplex (R-IBFD) cooperative communication scheme is proposed in this article that involves Full-Duplex (FD) and Non-Orthogonal Multiple Access (NOMA) technologies. The proposed R-IBFD provides efficient use of spectrum with better system parameters including Secrecy Outage Probability (SOP), throughput, data rate and secrecy capacity to fulfil the requirements of a smart city for 6th Generation (6thG or 6G). The proposed system targets the requirement of new algorithms that contribute towards better change and bring the technological revolution in the requirements of 6G. In this article, the proposed R-IBFD mainly contributes towards co-channel interference and security problem. The In-Band Full-Duplex mode devices face higher co-channel interference in between their own transmission and receiving antenna. R-IBFD minimizes the effect of such interference and assists in the security of a required wireless communication system. For a better understanding of the system contribution, the improvement of secrecy capacity and interference with R-IBFD is discussed with the help of SOP derivation, equations and simulation results. A machine learning genetic algorithm is one of the optimization tools which is being used to maximize the secrecy capacity.