scholarly journals Wideband beamspace squint user grouping algorithm based on subarray collaboration

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Xiaoliang Pan ◽  
Chunguo Li ◽  
Luxi Yang
Keyword(s):  
Optimization Problem ◽  
Base Station ◽  
Line Of Sight ◽  
Planar Antenna ◽  
Two Dimensional ◽  
Beam Direction ◽  
User Grouping ◽  
Constrained Problem ◽  
Wideband Communications ◽  
Grouping Algorithm

AbstractThe beam direction constrained problem is one of the important issues to be solved in millimeter-wave (mmWave) wideband communications when serving multi-user with squint beams whose direction varies with frequency. In this paper, we improve the number of simultaneous users served by collaboratively transmitting squint beams among multi-subarray at the base station (BS) end in a downlink multi-user line-of-sight (LoS) scenario, and reduce the interference among co-channel squint beams by a beam domain approach. The optimization problem of maximizing the number of users served in the system by transmitting beams in the two-dimensional beamspace of the planar antenna subarray is proposed and its suboptimal algorithm is given. Finally, the feasibility of the proposed method and the performance of the proposed algorithm are verified by numerical simulations.

Performance Improvement of MU-MIMO System by Optimizing the K-Factor for the K-Mean User Grouping Algorithm

2016 ◽  
Vol 5 (3) ◽  
pp. 89
Author(s):  
Ankush Kansal ◽  
Pawandeep Singh
Keyword(s):  
Mimo System ◽  
Access Point ◽  
Base Station ◽  
Optimum Number ◽  
Multiuser Mimo ◽  
User Grouping ◽  
Single Antenna ◽  
User Groups ◽  
Sum Rate ◽  
Grouping Algorithm

<p>In this paper, downlink multiuser-MIMO system with large number of transmitting antennas at the base station and R user terminals each having single antenna is considered. According to this design, an access point communicates with large number of users in the Rayleigh fading scenario. Due to large number of users, it becomes difficult to accommodate all of them in the system simultaneously. So, a user grouping technique known as K-mean clustering is used, such that a group of users with similar conditions at that particular time are served together. While making groups, the interference is surely reduced but the number of users being served at a time also reduces. So, it is necessary to make out the balance such that the performance of the system is maintained while accommodating maximum number of users. So, optimum number of user groups needs to be formed. The results show that when groups are increased from two till four sum rate increases but when five groups are made the sum rate decreases to a point but, is still higher than two groups.</p><p> </p>

scholarly journals Max-Min Fairness and Sum Throughput Maximization for In-Band Full-Duplex IoT Networks: User Grouping, Bandwidth and Power Allocation

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2182
Author(s):  
Ngo Tan Vu Khanh ◽  
Van Dinh Nguyen
Keyword(s):  
Iterative Algorithm ◽  
Optimization Problem ◽  
Base Station ◽  
Throughput Maximization ◽  
Full Duplex ◽  
Quadratic Program ◽  
User Grouping ◽  
Grouping Method ◽  
Network Interference ◽  
Inner Approximation

The skyrocketing growth in the number of Internet of Things (IoT) devices has posed a huge traffic demand for fifth-generation (5G) wireless networks and beyond. In-band full-duplex (IBFD), which is theoretically expected to double the spectral efficiency of a half-duplex wireless channel and connect more devices, has been considered as a promising technology in order to accelerate the development of IoT. In order to exploit the full potential of IBFD, the key challenge is how to handle network interference (including self-interference, co-channel interference, and multiuser interference) more effectively. In this paper, we propose a simple yet efficient user grouping method, where a base station (BS) serves strong downlink users and weak uplink users and vice versa in different frequency bands, mitigating severe network interference. First, we aim to maximize a minimum rate among all of the users subject to bandwidth and power constraints, which is formulated as a nonconvex optimization problem. By leveraging the inner approximation framework, we develop a very efficient iterative algorithm for solving this problem, which guarantees at least a local optimal solution. The proposed iterative algorithm solves a simple convex program at each iteration, which can be further cast to a conic quadratic program. We then formulate the optimization problem of sum throughput maximization, which can be solved by the proposed algorithm after some slight modifications. Extensive numerical results are provided to show not only the benefit of using full-duplex radio at BS, but also the advantage of the proposed user grouping method.

scholarly journals Correlation Investigation for Uniform Circular Array Based on Measured Massive MIMO

2019 ◽  
Vol 33 (09) ◽  
pp. 1958010
Author(s):  
Yanping Lu ◽  
Cheng Tao ◽  
Liu Liu
Keyword(s):  
Massive Mimo ◽  
Field Measurements ◽  
Base Station ◽  
Line Of Sight ◽  
Two Dimensional ◽  
Circular Array ◽  
Parameter System ◽  
Correlation Characteristic ◽  
Spatial Parameters ◽  
Angle Parameter

In this paper, the performance of a two-dimensional (2D) Massive MIMO angle parameter system with a uniform circular array (UCA) topology at base station is studied based on the field measurements in indoor line-of-sight (LOS) scenario at a frequency of 4.45[Formula: see text]GHz. Many spatial parameters are extracted, including angle information and correlation characteristic. It is shown that correlation lies between antenna elements and users. It is illustrated in the envelope correlation coefficient which goes on a downward trend while the antenna spacing is increasing in the measurements.

CALCULATION OF THE DEPENDENCE OF THE DISTANCE TO THE LOCATED OBJECT FROM THE CORNER POSITION OF THE VEHICLE LINE

2018 ◽  
pp. 14-18
Author(s):  
V. V. Artyushenko ◽  
A. V. Nikulin
Keyword(s):  
Real Time ◽  
Statistical Physics ◽  
Angular Position ◽  
Three Dimensional ◽  
Line Of Sight ◽  
Two Dimensional ◽  
Radar Station ◽  
Flight Mode ◽  
Vector Algebra ◽  
Analytical Expressions

To simulate echoes from the earth’s surface in the low flight mode, it is necessary to reproduce reliably the delayed reflected sounding signal of the radar in real time. For this, it is necessary to be able to calculate accurately and quickly the dependence of the distance to the object being measured from the angular position of the line of sight of the radar station. Obviously, the simplest expressions for calculating the range can be obtained for a segment or a plane. In the text of the article, analytical expressions for the calculation of range for two-dimensional and three-dimensional cases are obtained. Methods of statistical physics, vector algebra, and the theory of the radar of extended objects were used. Since the calculation of the dependence of the range of the object to the target from the angular position of the line of sight is carried out on the analytical expressions found in the paper, the result obtained is accurate, and due to the relative simplicity of the expressions obtained, the calculation does not require much time.

scholarly journals Robust Beamforming Design for Secure V2X Downlink System with Wireless Information and Power Transfer under a Nonlinear Energy Harvesting Model

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3294 ◽  
Author(s):  
Shidang Li ◽  
Chunguo Li ◽  
Weiqiang Tan ◽  
Baofeng Ji ◽  
Luxi Yang
Keyword(s):  
Energy Harvesting ◽  
Traffic Safety ◽  
Optimization Problem ◽  
Optimal Solution ◽  
Base Station ◽  
Power Splitting ◽  
Power Transfer ◽  
Vehicular Communication ◽  
Downlink System ◽  
Nonlinear Energy

Vehicle to everything (V2X) has been deemed a promising technology due to its potential to achieve traffic safety and efficiency. This paper considers a V2X downlink system with a simultaneous wireless information and power transfer (SWIPT) system where the base station not only conveys data and energy to two types of wireless vehicular receivers, such as one hybrid power-splitting vehicular receiver, and multiple energy vehicular receivers, but also prevents information from being intercepted by the potential eavesdroppers (idle energy vehicular receivers). Both the base station and the energy vehicular receivers are equipped with multiple antennas, whereas the information vehicular receiver is equipped with a single antenna. In particular, the imperfect channel state information (CSI) and the practical nonlinear energy harvesting (EH) model are taken into account. The non-convex optimization problem is formulated to maximize the minimum harvested energy power among the energy vehicular receivers satisfying the lowest harvested energy power threshold at the information vehicular receiver and secure vehicular communication requirements. In light of the intractability of the optimization problem, the semidefinite relaxation (SDR) technique and variable substitutions are applied, and the optimal solution is proven to be tight. A number of results demonstrate that the proposed robust secure beamforming scheme has better performance than other schemes.

scholarly journals A Method of Implementing a 4 × 4 Correlation Matrix for Evaluating the Uplink Channel Properties of MIMO Over-the-Air Apparatus

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6184
Author(s):  
Kazuhiro Honda
Keyword(s):  
Correlation Matrix ◽  
Channel Model ◽  
Multiple Input Multiple Output ◽  
Correlation Coefficients ◽  
Base Station ◽  
Theoretical Formula ◽  
Secondary Wave ◽  
Two Dimensional ◽  
Mimo Antenna ◽  
Channel Properties

This paper presents a method of implementing a 4 × 4 correlation matrix for evaluating the uplink channel properties of multiple-input multiple-output (MIMO) antennas using an over-the-air measurement system. First, the implementation model used to determine the correlation coefficients between the signals received at the base station (BS) antennas via the uplink channel is described. Then, a methodology is introduced to achieve a 4 × 4 correlation matrix for a BS MIMO antenna based on Jakes’ model by setting the initial phases of the secondary wave sources in the two-dimensional channel model. The performance of the uplink channel for a four-element MIMO terminal array antenna is evaluated using a two-dimensional bidirectional fading emulator. The results show that the measured correlation coefficients between the signals received via the uplink channel at the BS antennas using the proposed method are in good agreement with the BS correlation characteristics calculated using Monte Carlo simulation and the theoretical formula, thereby confirming the effectiveness of the proposed method.

scholarly journals Animated Two-Dimensional Barcode Generation Using Optimization Algorithms – Redesign of Formulation, Operator, and Quality Evaluation

2009 ◽  
Vol 13 (3) ◽  
pp. 245-254 ◽  
Author(s):  
Satoshi Ono ◽  
◽  
Kensuke Morinaga ◽  
Shigeru Nakayama
Keyword(s):  
Code Generation ◽  
Optimization Problem ◽  
Quality Evaluation ◽  
Qr Code ◽  
Two Dimensional ◽  
Quick Response ◽  
Qr Codes ◽  
Running Head ◽  
Generation Problem ◽  
Font Color

To improve on our previously proposed but problem-plagued innovation for generating animated and illustrated Quick Response (QR) codes, this paper proposes a method which formulates the animated QR code generation problem as an optimization problem rather than as a set of still QR code decoration problems. The proposed method also uses optimization operators designed for this problem and quality evaluation to maintain natural, smooth movement. Experiments demonstrate that the proposed method can generate animated QR codes involve a maximum of eight illustrations moving inside the code which maintaining decoding feasibility and smooth illustration movement.<FONT color="red" size="3">Erratum<br /></FONT> <FONT color="red" size="2">Due to a wrong manipulation during the correction of the proofs of the above paper, the running head title (short title) was incorrect. The correct running head title should have read as "Animated Two–Dimensional Barcode Generation."</FONT>

scholarly journals Base Station Selection for Hybrid TDOA/RTT/DOA Positioning in Mixed LOS/NLOS Environment

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4132
Author(s):  
Zhongliang Deng ◽  
Hanhua Wang ◽  
Xinyu Zheng ◽  
Lu Yin
Keyword(s):  
Selection Method ◽  
Base Station ◽  
Line Of Sight ◽  
Positioning Accuracy ◽  
Channel Condition ◽  
Fifth Generation ◽  
Hybrid Positioning ◽  
Channel Conditions ◽  
Geometric Dilution Of Precision ◽  
Value Changes

The fifth generation (5G) cellular communication system is designed to support Time Difference of Arrival (TDOA), Round-Trip Time (RTT), and Direction of Arrival (DOA) measurements for indoor positioning. To mitigate the positioning error caused by non-line-of-sight (NLOS), existing base station selection methods identify channel conditions and only use line-of-sight (LOS) signals for positioning. However, different selected base station combination would lead to a different geometric dilution of precision (GDOP), base station selection based only on channel condition is not fully applicable for the hybrid positioning. This paper derives the GDOP for the hybrid TDOA, RTT, and DOA positioning, and proposes a GDOP-assisted base station selection method, which is based on both channel conditions and GDOP value changes. The simulation shows that using the proposed base station selection method could lead to higher positioning accuracy than base station selection based only on channel condition. In the simulation, in the side region of the scenario, where the change of selected base station combination causes a notable increment in GDOP value, the positioning accuracy improvement caused by the proposed method is greater than that in the center region.

scholarly journals Shells and Encounters of Disk Galaxies with Ellipticals

1987 ◽  
Vol 127 ◽  
pp. 473-474
Author(s):  
Tsvi Piran ◽  
Jens Verner Villumsen
Keyword(s):  
Disk Galaxy ◽  
Line Of Sight ◽  
Disk Galaxies ◽  
Two Dimensional ◽  
Small Disk ◽  
Radial Orbit

Faint shells have been found around a large number of ellipticals (Malin and Carter 1980, 1983; Schweizer, 1980). Quinn (1984) has suggested that shells form around ellipticals when a small disk galaxy is tidally disrupted in a near radial orbit. According to this mechanism the remnants of the nearly two-dimensional disk maintain their dimensionality and form sheets. These sheets will phasewrap around the elliptical, and the shells are seen when the line of sight is tangent to one of these surfaces (Quinn 1984, Hernquist and Quinn 1986a,b,c).

Sign in / Sign up

Export Citation Format

Share Document