A new structure of coupled-fed loop antenna con- nected with two branch radiators for eight-band LTE/WWAN (LTE700/GSM850/900/1800/1900/UMTS/LTE2300/2500) operation in the ultra-thin laptop computer is presented. The t...
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A new structure of coupled-fed loop antenna con- nected with two branch radiators for eight-band LTE/WWAN (LTE700/GSM850/900/1800/1900/UMTS/LTE2300/2500) operation in the ultra-thin laptop computer is presented. The two branch strips of the antenna are e±cient radiators and contributing multi-resonant modes to greatly enhance the bandwidth of the antenna. The proposed antenna on the top shielding metal wall of the laptop display, with a planar and compact size of 12:5 × 70 × 0:8mm3, is suitable to be embedded inside the casing of the laptop computer. The proposed antenna is fabricated and tested, and good radiation performances are obtained. Compared with the existing published antennas, the volume of the planar antenna is quite small.
IEEE 802.11 is a protocol standard widely used in wireless local area network (WLAN). For the distributed coordination function (DCF) of IEEE 802.11 MAC layer, the binary exponential backoff (BEB) algorithm has the de...
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IEEE 802.11 is a protocol standard widely used in wireless local area network (WLAN). For the distributed coordination function (DCF) of IEEE 802.11 MAC layer, the binary exponential backoff (BEB) algorithm has the defect of poor access fairness. To address this issue, the design criteria of backoff algorithm is generalized from the analysis of the key performance parameters of DCF, and then a logarithmic backoff (LB) algorithm based on dynamic contention window (CW) adjustment is proposed. The algorithm dynamically adjusts the initial value of CW and the backoff size of the CW by using the logarithmic function that takes the number of network competing nodes as the variable. Simulation results show that compared with the BEB algorithm, the LB algorithm can effectively improve the fairness performance and the throughput performance, and also reduce network delay.
A compact multiband omnidirectional antenna for the reception of GNSS signals on artillery projectiles is designed in this paper. The proposed antenna consists of a metallic cone comprising a T-shaped monopole. It exh...
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In this paper, a deep learning optimization method combining U-net model and cycle generative adversarial network (Cycle-GAN) is proposed to efficiently solve the electromagnetic inverse scattering (EMIS) problems. Fi...
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A wideband omnidirectional horizontally polarized (HP) antenna is proposed and investigated in this paper. The antenna is composed of four arc printed dipoles, a small circular patch, four tapered microstrip transmiss...
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A wideband omnidirectional horizontally polarized (HP) antenna is proposed and investigated in this paper. The antenna is composed of four arc printed dipoles, a small circular patch, four tapered microstrip transmission lines and four pairs of parasitic strips. To verify the performance of the antenna, simulations and measurements are carried out and discussed. The measured results show that the proposed antenna exhibits a 10-dB impedance bandwidth of 59.3% (2.23- 4.11 GHz). With an omnidirectional radiation pattern in E-plane, the proposed antenna has a peak gain of around 2 dBi across the operational band. The low profile and compact design, along with omnidirectional radiation pattern, make it ideal for wireless applications operated within WLAN (2.4- 2.484 GHz) and WiMAX (2.3GHz, 2.5GHz and 3.5GHz) frequency bands.
In this article, an omnidirectional circularly polarized (CP) patch antenna with bandwidth broadening is proposed. The antenna is composed of a circular patch with four L-shaped slots, a ground plane loaded a metal sl...
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In this article, an omnidirectional circularly polarized (CP) patch antenna with bandwidth broadening is proposed. The antenna is composed of a circular patch with four L-shaped slots, a ground plane loaded a metal sleeve and a set of conductive vias. In order to broaden the impedance bandwidth, four parasitic strips are also sequentially rotated around the patch. As a result, it exhibits an omnidirectional CP radiation in the azimuthal plane. To verify the design, a prototype operating at 2.4 GHz industrial, scientific and medical band (ISM band) has been fabricated and measured. Measurement results show that the proposed antenna can achieve a -10 dB impedance bandwidth of 8.2% (ranges from 2.33 to 2.53 GHz) and a 3 dB axial ratio (AR) bandwidth of 9.2% (ranges from 2.29 to 2.51 GHz) in the azimuthal plane. The results indicate that the proposed antenna is a good candidate for 2.4 GHz ISM band applications.
In the scenario of time division duplexing(TDD) massive multiple-input multiple-output(MIMO) system,when there is pilot contamination(PC) in the uplink,different pilot allocation schemes will affect the results of the...
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In the scenario of time division duplexing(TDD) massive multiple-input multiple-output(MIMO) system,when there is pilot contamination(PC) in the uplink,different pilot allocation schemes will affect the results of the uplink channel *** the channel estimation results are used for downlink transmission precoding,which will further affects the downlink *** paper analyses the impact of different pilot allocation(PA) schemes on downlink *** theoretical analysis,the system downlink signal to interference plus noise ratio(SINR) and spectral efficiency expressions of different pilot allocation schemes are obtained *** simulation results show that the pilot allocation schemes with cell grouping is better than the schemes without cell *** SINR increases as the number of cell grouping increases,and the spectrum efficiency increases first and then decreases as the number of cell grouping increases.
The noncontact detection methods of blood volume pulse (BVP) based on facial videos have become a hot spot in recent years. However, these kinds of methods are highly sensitive to face movement. To address this proble...
The noncontact detection methods of blood volume pulse (BVP) based on facial videos have become a hot spot in recent years. However, these kinds of methods are highly sensitive to face movement. To address this problem, a novel BVP detection method based on kanade-lucas-tomasi (KLT) and independent component analysis (ICA) was proposed, in which, KLT method was employed for tracking and locating the region of interest (ROI) in facial images, and ICA method was used to improve the signal to noise ratio (SNR) of BVP signal. Based on 120 recorded facial videos, we carried out the comparative study of the proposed method and other commonly-used methods, the experimental results show that our method has obvious advantages in eliminating motion interference. In the implementation of the blind source separation method, we also conducted four separation methods. The results show that the second order blind identification (SOBI) algorithm is the best one to separate the BVP signal.
A novel watermarking sharing system having the ability of sharing gray-level secret images with multi-user is proposed. Multiple-based number system is used to split the secret into n meaningless shares, each share is...
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Despite numerous efforts on blur measurement of partially blurred images, there still lacks an effective blur measure that is both pixel-wise and locally sharp consistent. The paper proposes a novel method with two co...
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