Wireless Systems Research Articles

Research on path planning in UAV-assisted emergency communication

The rapid development of UAV communication technology makes it have application potential in wireless systems. However, for the optimization problem of UAV base station providing communication for ground personnel in the disaster area under special natural disasters, traditional deep reinforcement learning is used. Algorithms cannot solve such problems well. This article proposes the AD3QN algorithm combined with the attention mechanism, which can communicate with disaster victims on the ground better and more quickly, providing better information collection for rescue missions and completing the task of communication optimization. In the mission simulation environment, in order to make the environment more realistic, we innovatively designed the ground user distribution model, air-to-ground communication model, and electromagnetic interference model. Finally, the effect of the proposed algorithm is evaluated by comparing different deep reinforcement learning algorithms. The results show that the algorithm we proposed can provide communication services faster and has higher practicability in terms of algorithm.

Electromagnetic compatibility study of trackside antenna array miniaturization in the subway tunnel

Abstract To improve the compatibility of the subway tunnel’s electromagnetic environment and reduce the radiation impact of trackside antennas on subway workers. This paper proposes a miniaturized dual-band trackside antenna array by using metamaterial units. Its operation bandwidth is 2.33 ∼ 2.56 GHz and 3.24 ∼ 3.45 GHz, which could simultaneously satisfy the signal cover demands of the communications-based train control (CBTC) and the civil 5G wireless communication system. The proposed miniaturized antenna array has a maximum gain of 14.4 dBi and a maximum channel capacity of 13.9 bps Hz−1 at a signal-to-noise ratio (SNR) of 20 dB, which can effectively improve the quality of wireless communication systems. The number of trackside antennas with a single operation frequency band is reduced, and the distance between the antennas is enlarged at the same time. Besides that, we analyze the radiation impact on the tunnel electromagnetic environment of the proposed trackside antenna array. In particular, the electromagnetic dose absorbed by the human model of a tunnel worker is quantized. The results show that the electric field strength in the tunnel reduces by 4.11% at least after antenna array miniaturization, and the specific absorption rate (SAR) absorbed by the worker model’s trunk, skull, brain, heart, and liver is reduced by a maximum of 19.02%, 33.16%, 28.27%, 41.75%, and 74.54%, respectively, further lowering the human electromagnetic exposure risk. Therefore, a miniaturized trackside antenna array could reduce the interference from other radiation sources in the tunnel while providing a new idea for electromagnetic protection for subway workers.

Multidimensional QPSK symbol modulation scheme based on random sequence extraction for D-band photonics-aided wireless communication.

We propose a multidimensional (MD) quadrature phase shift keying (QPSK) symbol modulation and demodulation scheme based on random sequence extraction, which overcomes the limitations of traditional QPSK signals in performing probabilistic shaping. Unlike probabilistic shaping (PS) and geometric shaping (GS), our approach does not require modifications to the existing digital signal processing (DSP) architecture; it only necessitates the addition of sequence modulation and demodulation modules. Additionally, the source entropy (SE) can be flexibly adjusted. An experimental verification was conducted in a 50 m, 150 GHz photonics-aided wireless communication system. The results show that, under the same net data rate, the random sequence extraction QPSK scheme can achieve a maximum optical power gain of 0.7 dB. These findings indicate that the random sequence extraction QPSK (SE-QPSK) scheme can effectively enhance system performance, providing a promising outlook for future wireless communication.

An Optimized Multi-Level Control Method for Wireless Power Transfer System Using the Particle Swarm Optimization Algorithm

A Wireless Power Transfer (WPT) system, known for its contactless power delivery, is extensively used for power supply in spacecraft applications. Achieving efficient and stable power transfer necessitates the integration of DC/DC converters on both the primary and secondary sides of WPT systems for power conversion and control. Traditional efficiency optimization methods primarily focus on impedance matching within the wireless power resonance network, often neglecting the overall efficiency optimization of multi-stage DC-DC and WPT systems. This oversight results in suboptimal overall system efficiency despite optimal efficiency in the wireless transmission segment. Additionally, the time-varying nature of mutual inductance and load parameters during power transmission in WPT systems presents challenges for maximum efficiency tracking and power control. This paper introduces a multi-level coordinated control efficiency optimization method for WPT systems utilizing the particle swarm optimization (PSO) algorithm. This method takes into account the transmission losses across all power conversion units within the WPT system, establishing a mathematical model for the joint optimization of overall system transmission efficiency and power. The PSO algorithm is then employed to solve this optimization model using estimated mutual inductance and load values. By adjusting the DC/DC converters on both sides, the method ensures optimal overall system efficiency and consistent power transmission. Experimental results indicate that under varying load and mutual inductance conditions, a Series–Series (SS) compensated WPT system using this method achieves a 200 W power output with maximum efficiency tracking, a power output error of 0.63%, and an average transmission efficiency of 86.2%. This demonstrates superior power transmission stability and higher efficiency compared to traditional impedance matching methods.

OFDM system based on parametric DFT transform

This study introduces a specific type of orthogonal frequency division multiplexing (OFDM) system that relies on the parametric discrete Fourier transform (DFT-alpha), where alpha is a parameter randomly selected within the range [-2pi, 0]. We investigate the performance of the proposed system across various channel types and modulation formats, including binary phase shift keying (BPSK), 16 quadratic amplitude modulation (QAM), analyzing aspects such as bit-error rate (BER), peak-to-average power ratio (PAPR), and computational complexity. This work considers the most interesting special case of the one-parameter DFT, which is the DFT-π/6 . The simulated results confirm the suggested OFDM system’s ability to minimize the computational complexity of the conventional OFDM system, standing as the primary contribution of the current study, while maintaining the performance identical. Therefore, the parametric DFT-OFDM system would be a good alternative to the classical DFT-OFDM. The findings suggest that parametric DFT based OFDM holds significant potential for high-speed optical wireless communication systems.

Evolutionary optimisation of pixelated IFA inspired antennas

As wireless communication systems increasingly require compact and efficient antennas, conventional antenna design methods are proving difficult to meet the rigorous demands of modern applications. For this purpose, this study introduces a methodology which uses pixelated Inverted-F Antenna (IFA) inspired designs optimised through genetic algorithms to enhance performance in constrained spatial environments. As pixels the antenna features the exemplary use of Einstein Hat-shaped tiles, enabling the antenna to efficiently utilize space. A with the proposed method optimised antenna is compared to traditional IFA designs and shows improved properties like enhanced antenna gain and efficiency as well as smaller reflection coefficient offering a promising solution for future compact antenna systems in the Internet of Things and beyond. Finally, a prototype was manufactured and the scattering parameters and antenna gain were measured within an anechoic chamber.

Single laser based novel wavelength shift keying scheme for ground to satellite bidirectional links

Abstract Laser communication in space is gaining more recognition due to its ability to provide a much broader and unregulated data transmission capacity compared to traditional radio frequency systems, while also significantly decreasing the size, power requirements, and weight of the communication system. In this work, a novel technique for the generation of a wavelength shift keying (WSK) signal for the bidirectional transmission of 10 Gbps data between the ground station and low Earth orbit (LEO) satellite is presented. Our proposed scheme requires a single laser source to transmit WSK signal, that generally requires two wavelength sources to transmit the binary data bits. Furthermore, the scheme allows us to remodulate the optical signal received at the LEO satellite for downlink signal transmission. Therefore, the requirement of a laser source at the LEO satellite is eliminated, achieving the much desirable goals of low power consumption, weight and cost. The free space optical (FSO) channel is modelled using the gamma-gamma channel model. The performance of the proposed link is also compared with a conventional On-Off keying (OOK) based modulation scheme by using bit-error-rate (BER) as the performance metric.

Transfer learning enabled transformer-based generative adversarial networks for modeling and generating terahertz channels

Terahertz communications are envisioned as a promising technology for the sixth generation and beyond wireless systems, which can support wireless links with Terabits-per-second (Tbps) data rates. As the foundation of designing terahertz communications, channel modeling and characterization are crucial to scrutinize the potential of this spectrum. However, current channel modeling in the terahertz band heavily relies on time-consuming and costly measurements. Here, we propose a transfer learning enabled transformer based generative adversarial network to mitigate this problem in terahertz channel modeling. Specifically, as a fundamental building block, a generative adversarial network is exploited to generate channel parameters. To improve the accuracy, a transformer structure with a self-attention mechanism is incorporated in generative adversarial network. Still incurring errors compared with ground-truth measurement, a transfer learning is designed to solve the mismatch between the formulated network and measurement. The proposed method can achieve high accuracy in channel modeling, while requiring only rather limited amount of measurement, which is a promising complement of current channel modeling techniques.

Adaptive tunicate swarm optimization with partial transmit sequence for phase optimization in MIMO-OFDM

<span>Multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) are widely utilized in wireless systems and maximum data rate communications. The MIMO-OFDM technology increases the efficiency of spectrum utilization. The peak-to-average-power ratio (PAPR) minimization in MIMO-OFDM is a complex task in wireless communications systems. In this research, an adaptive tunicate swarm optimization with partial transmit sequence (ATSO-PTS) algorithm is proposed for a reduction of PAPR in MIMO-OFDM. The nonsquare-matrix-based differential space time coding (N-DSTC) scheme is used for the encoding and decoding process of MIMO-OFDM. The N-DSTC encoding and decoding are linear error-correcting codes that are utilized for message transmission over noisy channels. The pre-specified quadrate phase shift keying (QPSK) symbol is deployed for the modulation and demodulation scheme. On the receiver side, the serial to parallel (S/P) conversion, and fast Fourier transform (FFT) are accomplished, alongside the received data bits being demodulated to obtain the output bits. The proposed ATSO-PTS method achieves better results according to performance metrices PAPR, bit error rate (BER) and signal-to-noise-ratio (SNR), with values of about 2.9, 0.01 and 0.025, respectively. This ensures superior results when compared to the existing methods of twin symbol hybrid optimization applied to partial transmit sequence (TSHO-PTS), selective level mapping and PTS (SLM-PTS), and particle swarm and grey wolf (PS-GW) with PTS, respectively.</span>

Robust rateless space time block coding for mmWave massive MIMO system

In the vast growing wireless communication system creating robust encoding mechanisms using space-time block codes (STBC) for mmWave massive MIMO to overcome uncertainty and ensure reliability is a critical concept to be covered. This article reviews the core concepts behind MIMO communication, Massive MIMO communication, space-time block codes, and rateless codes in the context of wireless communication systems. Building on the foundational concepts of information theory and mmWave massive MIMO, we developed space-time block codes that maintain orthogonality for real-valued symbols. Following a thorough analysis of these codes, we successfully extended them into rateless orthogonal space-time block codes (ROSTBC) for massive MIMO. This extension enables the codes to adapt their rates dynamically based on the unknown channel conditions at the transmitter. The research work was concluded by comparing static G4 encoded Tarokah work and other Orthogonal Space Time Block Codes (OSTBCs) with Rateless Space Time Block Codes (ROSTBCs). The results show that as the number of blocks used to encode the message in Rateless Space Time Block Code (ROSTBC) increases, this coding scheme can outperform static Rateless Space Time Block Codes (OSTBC) in very low SNR values by a minimum of 8.5 %. This work can enhance wireless communication by creating reliable communication over inherently unreliable systems.

Structure optimization of transmission coil of wireless power transmission system for rail transit vehicles

Abstract To solve the transmission efficiency problem of traditional wireless energy systems applied to rail transit vehicles. In this paper, the key components of a wireless power transmission system, such as the transmission efficiency of the transmission coil and the poor anti-deviation ability of the coil, are studied. Firstly, this paper analyzes the traditional planar circular and square coil shapes, analyzes the magnetic field characteristics of the traditional transmission coil structures by ANSYS Maxwell simulation software, and obtains the advantages and disadvantages of different coil structures. According to the analysis structure, the coil structure is optimized and improved, and the coil structure form of the combined coil is put forward. Through the comparative analysis of finite element simulation software, it is attested that combined coil structure has a significant improvement in transmission efficiency and anti-deviation ability.

Wireless power supply near-infrared light drug-loaded microneedle system for the treatment of linear skin wounds

The healing of linear skin wounds is a complex biological process, and traditional treatment methods have certain limitations. This study proposes a wireless power supply near-infrared light drug-loaded microneedle system (NIR-LED-NG-R1-MN), which utilizes microneedles (MNs) to achieve targeted delivery of the active component of traditional Chinese medicine, Notoginsenoside R1 (NG-R1), and combines the biological regulatory effect of near-infrared light (NIR) to achieve efficient synergistic treatment for linear skin wounds. Experimental results show that the device can significantly promote the wound closure rate and reduce the levels of inflammatory factors and the risk of scar formation. By comparing the wound repair conditions of different treatment groups, it was found that the group treated with the NIR-LED-NG-R1-MN patch for NG-R1 and NIR synergistic treatment (MN@NG-R1@LED group) showed superior wound repair effects compared to other groups, thus confirming the synergistic therapeutic advantages of NG-R1 and NIR in skin wound healing. In addition, the application of wireless power supply technology used in this system eliminates the dependence on external power sources, enhancing the convenience of treatment. This study clearly demonstrates that the NIR-LED-NG-R1-MN has the potential to become a new clinical method for the treatment of linear skin wound healing.

Performance modeling and comparison of URLLC and eMBB coexistence strategies in 5G new radio systems

Performance modeling and comparison of URLLC and eMBB coexistence strategies in 5G new radio systems

Optimized Architecture for Efficient OFDMA Network Design

This study presents a novel approach to enhancing the design and performance of OFDMA (Orthogonal Frequency Division Multiple Access) networks, with a particular focus on WiMAX (Worldwide Interoperability for Microwave Access) for Best Effort (BE) services. The proposed method integrates a robust Markovian analytical model with four advanced scheduling algorithms: throughput fairness, resource fairness, opportunistic scheduling, and throttling. A sophisticated simulator was developed, incorporating an ON/OFF traffic generator, user-specific wireless channels, and a dynamic central scheduler to validate the model’s accuracy and evaluate its robustness by dynamically allocating radio resources per frame. The validation study showed that the proposed model reduced simulation time by over 90%, completing analytical calculations in just 15 min, compared to nearly 2 days for simulations using conventional scheduling algorithms. Performance metrics such as the average number of active users and resource utilization closely matched those from the validation study, confirming the model’s accuracy. In the robustness study, the model consistently performed well across diverse traffic distributions (exponential and Pareto) and channel conditions. The proposed architecture increased network throughput by up to 25% and reduced latency under dynamic conditions, demonstrating its scalability, adaptability, and efficiency as a crucial solution for next-generation wireless communication systems.

Low Power Dynamic and Asymmetric Inductive Wireless Power Transfer System to an Endoscopic Capsule

Low Power Dynamic and Asymmetric Inductive Wireless Power Transfer System to an Endoscopic Capsule

Timely Remote Control in Wireless Cyber-Physical System With Multiple Processes: A Cross-Time Slot Scheduling Policy

Timely Remote Control in Wireless Cyber-Physical System With Multiple Processes: A Cross-Time Slot Scheduling Policy

Determination and analysis of compensation capacitor for a robust distance-variable wireless power transfer system

Wireless power transfer (WPT) systems have been widely adopted for full autonomy in various fields due to their convenience. However, changes in the air gap between the Tx and Rx coils significantly affect efficiency. To overcome this challenge, this paper introduces the determination of a compensation capacitor for a distance-variable WPT system that is robust in varying air gap conditions. The proposed method was verified using theoretical analysis, simulation, and experimental measurement. The electrical circuit was modeled using a T-equivalent model in a series–series (SS) topology to calculate power transfer efficiency (PTE). Specifically, compensation capacitors were analyzed at distances of 10, 30, and 50 mm, considering different self-inductance values. These results are compared against varying load resistances to demonstrate the effectiveness of the proposed approach. Additionally, the PTE drop ratio was defined to facilitate comparison. The results show that the PTE drop ratio for the compensation capacitor at the farthest distance was consistently smaller than that for the capacitor at the nearest distance under varying air gaps and load resistances. In this research, the difference in the PTE drop ratio between 10 and 50 mm was measured, demonstrating that determining the capacitor at the farthest distance reduces the PTE drop ratio across a range of operational conditions.

Design of a stagger‐tuned high‐power low‐stress capacitive wireless power transfer system

AbstractCapacitive power transfer (CPT) has emerged as a promising alternative to traditional inductive methods. CPT offers advantages like cost‐effectiveness, reduced weight and volume, and greater tolerance to alignment errors. However, the high‐Q resonant circuits used as matching networks can be susceptible to high voltage stress, especially when transmitting substantial power. Consequently, designing matching networks for CPT systems necessitates consideration of multiple parameters, including practical constraints such as component losses and breakdown thresholds. In this work an innovative algorithm is presented for designing practical matching networks in CPT systems. The algorithm conducts a methodical search of potential solutions, and converges on component values that maximize power transfer efficiency whilst also minimizing component voltage stress. The proposed algorithm is demonstrated theoretically and experimentally.

Dynamic parameter identification method for wireless charging system of AUV based on multi-strategy nonlinear rime algorithm

Dynamic parameter identification method for wireless charging system of AUV based on multi-strategy nonlinear rime algorithm

Average Energy Detection With Adaptive Threshold for Spectrum Sensing in Cognitive Radio Systems

Average Energy Detection With Adaptive Threshold for Spectrum Sensing in Cognitive Radio Systems