scholarly journals Beam Training for Millimeter-Wave Communication Based on Tabu Table Enhanced Rosenbrock Algorithm

2019 ◽  
Vol 11 (10) ◽  
pp. 214
Author(s):  
Li ◽  
Sun ◽  
Jiang
Keyword(s):  
Local Search ◽  
Success Rate ◽  
Millimeter Wave ◽  
Communication Systems ◽  
Optimization Problem ◽  
Local Optimum ◽  
Training Procedure ◽  
Beam Search ◽  
Original Algorithm ◽  
Wave Region

The codebook-based beamforming for millimeter-wave (mm Wave) communication systems is usually used to compensate the severe attenuation of the mm Wave region. The beam training process based on pre-specified beam codebooks is considered a global optimization problem in 2-D planes formed by the potential beam index. The Rosenbrock algorithm (RA) is adopted to implement optimum beam searching whereas the simulated annealing (SA) algorithm is used to solve the problem of falling into the local optimum, due to the unavailable gradient information of the objective function. However, the RA implements rounding to the integer which leads to the problem of repeated search and beam space discontinuity caused by beam index will impair the powerful local search ability. Thus, in this paper, an enhanced RA based on tabu search and combined with SA algorithm is proposed as an alternative solution for beam search success rate. The proposed algorithm reduces the search times by forbidding the repeat search with tabu table and design of neighbor region. Moreover, to prevent the search failure, the search candidate index is defined to keep the local search ability of the original algorithm and wrap around of beam index is applied to maintain continuity of the search direction. Experimental simulations show that the proposed technique can improve the search efficiency in terms of reduced steps and increase search success rate during the beam training procedure compared to existing techniques.

scholarly journals Noninferior Solution Grey Wolf Optimizer with an Independent Local Search Mechanism for Solving Economic Load Dispatch Problems

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2274 ◽  
Author(s):  
Jianzhong Xu ◽  
Fu Yan ◽  
Kumchol Yun ◽  
Lifei Su ◽  
Fengshu Li ◽  
...  
Keyword(s):  
Power Systems ◽  
Local Search ◽  
Optimization Problem ◽  
Search Strategy ◽  
Local Optimum ◽  
Economic Load Dispatch ◽  
Problem Solution ◽  
Main Task ◽  
Grey Wolf ◽  
Local Search Strategy

The economic load dispatch (ELD) problem is a complex optimization problem in power systems. The main task for this optimization problem is to minimize the total fuel cost of generators while also meeting the conditional constraints of valve-point loading effects, prohibited operating zones, and nonsmooth cost functions. In this paper, a novel grey wolf optimization (GWO), abbreviated as NGWO, is proposed to solve the ELD problem by introducing an independent local search strategy and a noninferior solution neighborhood independent local search technique to the original GWO algorithm to achieve the best problem solution. A local search strategy is added to the standard GWO algorithm in the NGWO, which is called GWOI, to search the local neighborhood of the global optimal point in depth and to guarantee a better candidate. In addition, a noninferior solution neighborhood independent local search method is introduced into the GWOI algorithm to find a better solution in the noninferior solution neighborhood and ensure the high probability of jumping out of the local optimum. The feasibility of the proposed NGWO method is verified on five different power systems, and it is compared with other selected methods in terms of the solution quality, convergence rate, and robustness. The compared experimental results indicate that the proposed NGWO method can efficiently solve ELD problems with higher-quality solutions.

scholarly journals Digitized Reconfigurable Metal Reflectarray Surfaces for Millimeter-Wave Beam-Engineering

2021 ◽  
Vol 11 (13) ◽  
pp. 5811
Author(s):  
Minwoo Yi ◽  
Youngseok Bae ◽  
Sungjun Yoo ◽  
Joonho So
Keyword(s):  
Millimeter Wave ◽  
Communication Systems ◽  
Satellite Communication ◽  
High Gain ◽  
Phase Control ◽  
Metal Plate ◽  
Field Patterns ◽  
Wave Region ◽  
Gain Loss ◽  
Reflecting Surfaces

Digitized beam-forming metal reflectarray antennas are designed for the millimeter-wave region. The phase control of antennas has been implemented by the reconfiguration of rectangular grooves on a metal plate. The antenna has 1147 elements arranged in an aluminum metal plate. The depths of all metal grooves are manipulated for designed phase control of high-gain beam-aimed reflectors. We have demonstrated a digitized reconfigurable metal reflectarray to steer a re-radiated millimeter-wave field from the reflector in a two-dimensional scanning plane from −20∘ to 20∘. The far-field patterns show that the measured gain of the 2-bit reflectarray is only 1 dB lower than that of a non-digitized reflectarray antenna. The measured peak gain is higher than 31.7 dB, and the measurements show that the gain of the full 40∘ scanned beam is 31.7 dB and well-defined scanned beams are obtained with a maximum scan gain loss of 0.2 dB. The proposed reconfigurable antennas can be a useful candidate for high-gain beam-aimed antennas for practical reflecting surfaces and a variety of wireless and satellite communication systems.

Opinion Dynamics Optimization by Varying Susceptibility to Persuasion via Non-Convex Local Search

2021 ◽  
Vol 16 (2) ◽  
pp. 1-34
Author(s):  
Rediet Abebe ◽  
T.-H. HUBERT Chan ◽  
Jon Kleinberg ◽  
Zhibin Liang ◽  
David Parkes ◽  
...  
Keyword(s):  
Local Search ◽  
Objective Function ◽  
Iterative Process ◽  
Large Scale ◽  
Opinion Dynamics ◽  
Theoretical Models ◽  
Global Optimum ◽  
Local Optimum ◽  
Opinion Formation ◽  
Long Line

A long line of work in social psychology has studied variations in people’s susceptibility to persuasion—the extent to which they are willing to modify their opinions on a topic. This body of literature suggests an interesting perspective on theoretical models of opinion formation by interacting parties in a network: in addition to considering interventions that directly modify people’s intrinsic opinions, it is also natural to consider interventions that modify people’s susceptibility to persuasion. In this work, motivated by this fact, we propose an influence optimization problem. Specifically, we adopt a popular model for social opinion dynamics, where each agent has some fixed innate opinion, and a resistance that measures the importance it places on its innate opinion; agents influence one another’s opinions through an iterative process. Under certain conditions, this iterative process converges to some equilibrium opinion vector. For the unbudgeted variant of the problem, the goal is to modify the resistance of any number of agents (within some given range) such that the sum of the equilibrium opinions is minimized; for the budgeted variant, in addition the algorithm is given upfront a restriction on the number of agents whose resistance may be modified. We prove that the objective function is in general non-convex. Hence, formulating the problem as a convex program as in an early version of this work (Abebe et al., KDD’18) might have potential correctness issues. We instead analyze the structure of the objective function, and show that any local optimum is also a global optimum, which is somehow surprising as the objective function might not be convex. Furthermore, we combine the iterative process and the local search paradigm to design very efficient algorithms that can solve the unbudgeted variant of the problem optimally on large-scale graphs containing millions of nodes. Finally, we propose and evaluate experimentally a family of heuristics for the budgeted variant of the problem.

scholarly journals Triangular Slot-Loaded Wideband Planar Rectangular Antenna Array for Millimeter-Wave 5G Applications

Electronics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 778
Author(s):  
Iftikhar Ahmad ◽  
Houjun Sun ◽  
Umair Rafique ◽  
Zhang Yi
Keyword(s):  
Antenna Array ◽  
Millimeter Wave ◽  
Communication Systems ◽  
Ground Plane ◽  
Simulated Data ◽  
Impedance Bandwidth ◽  
Antenna Element ◽  
Single Antenna ◽  
Rectangular Patch ◽  
Half Power

This paper presents a design of a triangular slot-loaded planar rectangular antenna array for wideband millimeter-wave (mm-wave) 5G communication systems. The proposed array realizes an overall size of 35.5 × 14.85 mm2. To excite the array elements, a four-way broadband corporate feeding network was designed and analyzed. The proposed array offered a measured impedance bandwidth in two different frequency ranges, i.e., from 23 to 24.6 GHz and from 26 to 45 GHz. The single-antenna element of the array consists of a rectangular patch radiator with a triangular slot. The partial ground plane was used at the bottom side of the substrate to obtain a wide impedance bandwidth. The peak gain in the proposed array is ≈12 dBi with a radiation efficiency of >90%. Furthermore, the array gives a half-power beamwidth (HPBW) of as low as 12.5°. The proposed array has been fabricated and measured, and it has been observed that the measured results are in agreement with the simulated data.

scholarly journals An Enhanced Multi-Objective Particle Swarm Optimization in Water Distribution Systems Design

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1334
Author(s):  
Mohamed R. Torkomany ◽  
Hassan Shokry Hassan ◽  
Amin Shoukry ◽  
Ahmed M. Abdelrazek ◽  
Mohamed Elkholy
Keyword(s):  
Particle Swarm Optimization ◽  
Local Search ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Particle Swarm ◽  
Large Network ◽  
Swarm Optimization ◽  
Original Algorithm ◽  
Multi Objective

The scarcity of water resources nowadays lays stress on researchers to develop strategies aiming at making the best benefit of the currently available resources. One of these strategies is ensuring that reliable and near-optimum designs of water distribution systems (WDSs) are achieved. Designing WDSs is a discrete combinatorial NP-hard optimization problem, and its complexity increases when more objectives are added. Among the many existing evolutionary algorithms, a new hybrid fast-convergent multi-objective particle swarm optimization (MOPSO) algorithm is developed to increase the convergence and diversity rates of the resulted non-dominated solutions in terms of network capital cost and reliability using a minimized computational budget. Several strategies are introduced to the developed algorithm, which are self-adaptive PSO parameters, regeneration-on-collision, adaptive population size, and using hypervolume quality for selecting repository members. A local search method is also coupled to both the original MOPSO algorithm and the newly developed one. Both algorithms are applied to medium and large benchmark problems. The results of the new algorithm coupled with the local search are superior to that of the original algorithm in terms of different performance metrics in the medium-sized network. In contrast, the new algorithm without the local search performed better in the large network.

scholarly journals Millimeter Wave Spatial Channel Characterization for Vehicular Communications

Proceedings ◽  
2019 ◽  
Vol 42 (1) ◽  
pp. 64 ◽  
Author(s):  
Fidel Rodríguez-Corbo ◽  
Leyre Azpilicueta ◽  
Mikel Celaya-Echarri ◽  
Peio López-Iturri ◽  
Imanol Picallo ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
Autonomous Vehicles ◽  
Communication Systems ◽  
Vehicular Networks ◽  
Small Scale ◽  
Vehicular Communications ◽  
Next Generation ◽  
Vehicular Communication ◽  
High Definition ◽  
High Data

With the growing demand of vehicle-mounted sensors over the last years, the amount of critical data communications has increased significantly. Developing applications such as autonomous vehicles, drones or real-time high-definition entertainment requires high data-rates in the order of multiple Gbps. In the next generation of vehicle-to-everything (V2X) networks, a wider bandwidth will be needed, as well as more precise localization capabilities and lower transmission latencies than current vehicular communication systems due to safety application requirements; 5G millimeter wave (mmWave) technology is envisioned to be the key factor in the development of this next generation of vehicular communications. However, the implementation of mmWave links arises with difficulties due to blocking effects between mmWave transceivers, as well as different channel impairments for these high frequency bands. In this work, the mmWave channel propagation characterization for V2X communications has been performed by means of a deterministic in-house 3D ray launching simulation technique. A complex heterogeneous urban scenario has been modeled to analyze the different propagation phenomena of multiple mmWave V2X links. Results for large and small-scale propagation effects are obtained for line-of-sight (LOS) and non-LOS (NLOS) trajectories, enabling inter-data vehicular comparison. These analyzed results and the proposed methodology can aid in an adequate design and implementation of next generation vehicular networks.

A Contribution to the Microwave Double Resonance Technique and Measurements of Collision Induced Transitions

1979 ◽  
Vol 34 (5) ◽  
pp. 571-574 ◽  
Author(s):  
H. Dreizier ◽  
W. Schrepp ◽  
R. Schwarz
Keyword(s):  
Millimeter Wave ◽  
Double Resonance ◽  
Absorption Cell ◽  
Resonance Technique ◽  
Wave Region

Abstract A construction for a versatile absorption cell is presented, which may be used for a large variety of double resonance experiments in the radiofrequency, microwave and millimeter wave region. Some measurements of collision induced transitions are reported.

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