Jaanus Kalde, Veli-Pekka Kutinlahti, Anu Lehtovuori
et al.
Traditional antenna array design aims at minimising the mutual coupling between the elements. When elements are fully isolated, the active impedance seen by the amplifiers does not depend on the beam steering angle. However, at the same time, the mutual coupling can not be exploited in re-configuring the operation of the antenna-amplifier system. In this paper, we show experimentally that increased mutual coupling between array elements can broaden the operation band of the system without any sacrifice in the efficiency or transmitted power. This severely challenges the traditional design paradigm and suggests that amplifiers and antennas should be co-designed.
Telecommunication, Electric apparatus and materials. Electric circuits. Electric networks
Abstract Implementation of reconfigurable metasurfaces demands a complex structure. The design methodology for metasurface elements based on PIN diodes requires targeted optimisation tailored to the varying application environments and cannot be directly transplanted from one methodological approach to another. In addition, inclusion of varactors often imposes undesirable high‐power consumption with complex analog drive circuitry. Furthermore, the design method for the reconfigurable metasurface element has not been simplified and unified, hindering the rapid deployment of metasurface applications. The authors propose a general design model based on low‐power embedded circuitry for a multi‐function metasurface element and give the corresponding numerical analysis. The authors present a reconfigurable method based on the general design model and prove that the method achieves independent regulation of amplitude and phase for the reflected electromagnetic wave. Through analysis of the sensitive area at the bottom of the embedded circuit, a gradient descent algorithm is proposed to find the optimised phase points according to device sensitivity of the application scenario and suitable strategy. Finally, the authors demonstrate that the designed metasurface element possesses phase control capability and decent phase consistency obtained via far‐field scanning experiments. The proposed element design method will provide a theoretical reference for the integrated design of metasurface.
The unpredictable environmental changes cause large fluctuations in Wi-Fi signals, and it is difficult to quantify the static and behaviorally-aware dynamic components in the subcarriers, so it is not possible to accurately portray the fluctuating form of dynamic breathing characteristics.Based on this, a subcarrier mutual information breathing perception (SMIBP) system was proposed.Firstly, a form of inscribing dynamic component information (DCI) was proposed, and mutual information theory was utilized to extract the dynamic component information representing respiration in subcarriers.Then, analytic hierarchy process (AHP) was used to combine the subcarriers to maximize the dynamic characteristics of the respiratory signals to obtain the reconstructed DCI sensory base signals.Finally, the respiration rate was obtained by combining the wavelet transform and peak detection method, which revealed of a theoretical pathway representing the dynamic component of human respiration.Simulation results show that the proposed system can better characterize the dynamic breathing component in each subcarrier, and can significantly improve the sensing accuracy and range of Wi-Fi for small-scale actions in different scenarios.
Wiktor B. Daszczuk, Denny B. Czejdo, Wociech Grześkowiak
The article outlines a contemporary method for creating software for multi-processor computers. It describes the identification of parallelizable sequential code structures. Three structures were found and then carefully examined. The algorithms used to determine whether or not certain parts of code may be parallelized result from static analysis. The techniques demonstrate how, if possible, existing sequential structures might be transformed into parallel-running programs. A dynamic evaluation is also a part of our process, and it can be used to assess the efficiency of the parallel programs that are developed. As a tool for sequential programs, the algorithms have been implemented in C#. All proposed methods were discussed using a common benchmark.
Rukshan Darshana Wijesinghe, Dumindu Tissera, Mihira Kasun Vithanage
et al.
Recent advancements in artificial intelligence have enabled reinforcement learning (RL) agents to exceed human-level performance in various gaming tasks. However, despite the state-of-the-art performance demonstrated by model-free RL algorithms, they suffer from high sample complexity. Hence, it is uncommon to find their applications in robotics, autonomous navigation, and self-driving, as gathering many samples is impractical in real-world hardware systems. Therefore, developing sample-efficient learning algorithms for RL agents is crucial in deploying them in real-world tasks without sacrificing performance. This paper presents an advisor-based learning algorithm, incorporating prior knowledge into the training by modifying the deep deterministic policy gradient algorithm to reduce the sample complexity. Also, we propose an effective method of employing an advisor in data collection to train autonomous navigation agents to maneuver physical platforms, minimizing the risk of collision. We analyze the performance of our methods with the support of simulation and physical experimental setups. Experiments reveal that incorporating an advisor into the training phase significantly reduces the sample complexity without compromising the agent’s performance compared to various benchmark approaches. Also, they show that the advisor’s constant involvement in the data collection process diminishes the agent’s performance, while the limited involvement makes training more effective.
In this paper, we analyze the average age of information (AoI) and the average peak AoI (PAoI) of a multiuser mobile edge computing (MEC) system where a base station (BS) generates and transmits computation-intensive packets to user equipments (UEs). In this MEC system, we focus on three computing schemes: (i) The local computing scheme where all computational tasks are computed by the local server at the UE, (ii) The edge computing scheme where all computational tasks are computed by the edge server at the BS, and (iii) The partial computing scheme where computational tasks are partially allocated at the edge server and the rest are computed by the local server. Considering exponentially distributed transmission time and computation time and adopting the first come first serve (FCFS) queuing policy, we derive closed-form expressions for the average AoI and average PAoI. To address the complexity of the average AoI expression, we derive simple upper and lower bounds on the average AoI, which allow us to explicitly examine the dependence of the optimal offloading decision on the MEC system parameters. Aided by simulation results, we verify our analysis and illustrate the impact of system parameters on the AoI performance.
Telecommunication, Transportation and communications
Cédric Lavenu, Cédric Chauvenet, Paolo Treffiletti
et al.
Considering the intrinsic benefits of power line communications, the long-lasting lifetime of industrial systems and the growth of IoT, PLC technologies will be part of the worldwide industrial landscape for many decades. This paper discusses the history of the G3-PLC technology and current challenges and opportunities identified in real systems. Finally, it introduces recent evolutions within the G3-PLC standard, which bring additional performance and versatility, enhancing the relevance of G3-PLC as a complementary technology to other telecommunication systems in a 5G-driven telecommunication technology landscape.
VLC has emerged as a prominent technology to address the radio spectrum shortage. It is characterized by the unlicensed and unexploited high bandwidth, and provides the system with cost-effective advantages because of the dual-use of light bulbs for illumination and communication and the low complexity design. It is considered to be utilized in various telecommunication systems, including 5G, and represents the key technology for light-fidelity. To this end, VLC has to be integrated into the existing telecommunication networks. Therefore, its analysis as a network technology is momentous. In this article, we consider the feasibility of using VLC as a network technology and discuss the challenges related to the implementation of a VLC-based network, as well as the integration of VLC into existing conventional networks and its inclusion in standards.
Exploring the limits of Fractal Electrodynamics for the future telecommunication technologies could also bring answers to the search of efficient small antennas. In the miniaturization of wire antennas it has been found that the electromagnetic coupling between wire angles limits the reduction of the resonant frequency with increasing wire length. This coupling effect has been studied for several Euclidean and Fractal shapes of different fractal dimension, in order to draw conclusions that could lead to guidelines for the reduction of self-resonant antennas size.
The telecommunication sector plays a significant role in shaping the global economy and the way people share information and knowledge. At present, the telecommunication sector is liable for its energy consumption and the amount of emissions it emits in the environment. In the context of off-grid telecommunication applications, off-grid base stations (BSs) are commonly used due to their ability to provide radio coverage over a wide geographic area. However, in the past, the off-grid BSs usually relied on emission-intensive power supply solutions such as diesel generators. In this review paper, various types of solutions (including, in particular, the sustainable solutions) for powering BSs are discussed. The key aspects in designing an ideal power supply solution are reviewed, and these mainly include the pre-feasibility study and the thermal management of BSs, which comprise heating and cooling of the BS shelter/cabinets and BS electronic equipment and power supply components. The sizing and optimization approaches used to design the BSs’ power supply systems as well as the operational and control strategies adopted to manage the power supply systems are also reviewed in this paper.
Patients with spinal cord injuries cannot move their limbs using their intact muscles. A suitable controller can be used to move their arms by employing the functional electrical stimulation method. In this article, a fuzzy exponential sliding‐mode controller is designed to move a musculoskeletal human arm model to track an optimal trajectory in the sagittal plane. This optimal arm trajectory is obtained by developing a policy for the central nervous system. In order to specify the optimal trajectory between two points, two dynamic and static optimal criteria are applied simultaneously. The first dynamic objective function is defined to minimize the joint torques, and the second static optimization is offered to minimize the muscle forces at each moment. In addition, fuzzy logic is used to tune the sliding‐surface parameter to enable an appropriate tracking performance. Simulation results are evaluated and compared with experimental data for upward and downward movements of the human arm.