In this article, a miniaturized reconfigurable 4-element ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna is proposed to operate from 2.52 to 24 GHz, and studied using characteristics mode analysis (...
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In this article, a miniaturized reconfigurable 4-element ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna is proposed to operate from 2.52 to 24 GHz, and studied using characteristics mode analysis (CMA). Initially, a 1-element antenna is designed and then extended to 4-element MIMO configuration. The MIMO antenna achieves design merits by orthogonally sorting fractal radiators for miniaturization, a Gamma-shaped slot for band-notching and rotationally symmetric connected ground for isolation. CMA is explored to study the band-notched behavior effect in antenna, which shows two operating modes, NM-mode and NB-mode (NM: normal-mode, NB: Notched-mode). The modal metrics is discussed for both modes giving an insights on the bandwidth and radiation potentials. Four RF p-i-n diodes are mounted at the Gamma-shaped slot orifice on each antennas, to control the band-notched operation. At OFF-state, the antenna is with wide-band-rejection from 3.7 to 8.87 GHz and at ON-state, it works in pure UWB mode. To demonstrate its feasibility, a fabricated antenna of size 24 mm x 24 mm is experimented which are in good agreements with simulated results.
This work presents a dual-element multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) for sub-6 GHz applications. The proposed MIMO-DRA has two major features: (i) circular polarization (CP);and (...
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This work presents a dual-element multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) for sub-6 GHz applications. The proposed MIMO-DRA has two major features: (i) circular polarization (CP);and (ii) high interport isolation. The proposed MIMO-DRA is formed by two identical antenna elements. Each element is composed of a cylindrical dielectric resonator (DR) which is fed by a microstrip line via the underneath octagonal aperture. A modified L-shaped strip along with the octagonal aperture delivers the desired CP characteristics. Meanwhile, a novel defected ground geometry (DGG) is utilized to enhance the inter-port isolation across the operating frequency bandwidth. The proposed MIMO-DRA has an inter-port isolation of greater than 21 dB over the operating 10-dB impedance band of 4.18-6.12 GHz. Furthermore, the proposed MIMO-DRA features broadside radiation patterns, satisfactory broadside gains, and well-acceptable values of envelope correlation coefficients (ECCs).
A compact two-element multiple-input-multiple-output (MIMO) antenna system with improved impedance matching and isolation is presented for future sub-6 GHz 5G applications. The two identical tapered microstrip line fe...
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A compact two-element multiple-input-multiple-output (MIMO) antenna system with improved impedance matching and isolation is presented for future sub-6 GHz 5G applications. The two identical tapered microstrip line fed modified rhombus-shaped radiating elements are placed in the same orientation at a compact substrate area of 0.24 lambda(0) x 0.42 lambda(0) (where, lambda(0) at 3.6 GHz) on a shared rectangular ground. A remodeled T-shaped ground stub is placed between a pair of radiating element to achieve improved impedance bandwidth and isolation. Further, a split U-shaped stub connected to center of each radiating element to achieve the desired resonant frequency of 3.6 GHz. The proposed antenna covers a -10 dB operating band of 3.34 to 3.87 GHz (530 MHz) with more than 20 dB isolation between a pair of elements. MIMO performances are also analyzed and experimentally validated. The measured performances of a prototype are found in good agreement with simulated performances. Further, the simulation study is carried out to see the effect of housing and extended ground plane on two-element MIMO antenna for practical application. An idea of realization of 12-element MIMO is also studied using the proposed two-element MIMO antenna.
A four-port multipleinputmultiple-output (MIMO) antenna with common radiating element is proposed for 2.4 GHz Wi-Fi applications. It comprises a modified circular radiator fed by four identical modified feedlines, p...
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A four-port multipleinputmultiple-output (MIMO) antenna with common radiating element is proposed for 2.4 GHz Wi-Fi applications. It comprises a modified circular radiator fed by four identical modified feedlines, partial ground planes, and a diagonal parasitic element (DPE). The parasitic element is used to enhance the interport isolation. The antenna has a 2:1 Voltage standing wave ratio (VSWR) impedance band 2.34-2.56GHz and nearly omnidirectional radiation patterns. The radiation efficiency is more than 79% and gain is 2 dBi at resonant 2.43GHz. The isolation in the given frequency band is 10 dB. At the 2.43GHz, the isolation between adjacent ports (1, 2 and 1, 4) is 14dB and between opposite ports (1, 3) is 12dB. The mean effective gain (MEG)-2.7 dB and envelope correlation coefficient is <0.01. The -10 dB total active reflection coefficient bandwidth is 202MHz. The antenna is designed for a Wi-Fi device and the effectiveness of antenna has been checked for distance of 1/2 feet from the human head. The specific absorption rate (SAR) is found to be 0.17W/Kg by CST simulation tool.
With the escalation of heterogeneous data traffic, the research on optical wireless communication (OWC) has attracted much attention, owing to its advantages such as wide spectrum, low power consumption and high secur...
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With the escalation of heterogeneous data traffic, the research on optical wireless communication (OWC) has attracted much attention, owing to its advantages such as wide spectrum, low power consumption and high security. Ubiquitous optical devices, e.g. light-emitting diodes (LEDs) and cameras, are employed to support optical wireless links. Since the distribution of these optical devices is usually dense, multiple-input-multiple-output (MIMO) can be naturally adopted to attain spatial diversity gain or spatial multiplexing gain. As the scale of OWC networks enlarges, optical MIMO can also collaborate with network-level operations, like user/AP grouping, to enhance the network throughput. Since OWC is preferred for short-range communications and is sensitive to the directions/rotations of transceivers, optical MIMO links vary frequently and sharply in outdoor scenarios when considering the mobility of optical devices, raising new challenges to network design. In this work, we present an overview of optical MIMO techniques, as well as the cooperation of MIMO and user/AP grouping in OWC networks. In consideration of the challenges for outdoor OWC, key technologies are then proposed to facilitate the adoption of optical MIMO in outdoor scenarios, especially in vehicular ad hoc networks. Lastly, future applications of MIMO in OWC networks are discussed. This article is part of the theme issue 'Optical wireless communication'.
Visible Light Communication (VLC) is a promising field in optical wireless communications, which uses the illumination infrastructure for data transmission. The important features of VLC are electromagnetic interferen...
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Visible Light Communication (VLC) is a promising field in optical wireless communications, which uses the illumination infrastructure for data transmission. The important features of VLC are electromagnetic interference-free, license-free, etc. Additionally, multiple-input-multiple-output (MIMO) techniques are enabled in the VLC for enhancing the limited modulation bandwidth by its spectral efficiency. The data transmission through the MIMO-VLC system is corrupted by different interferences, namely thermal noise, shot noise and phase noise, which are caused by the traditional fluorescent light. In this paper, an effective precoding technique, namely Block Bi-Diagonalization (BBD), is enabled to mitigate the interference occurring in the indoor MIMO-VLC communications. Besides, a Quadrature Amplitude Modulation (QAM) is used to modulate the signal before transmission. Here, the indoor MIMO-VLC system is developed to analyze the communication performance under noise constraints. The performance of the proposed system is analyzed in terms of Bit Error Rate (BER) and throughput. Furthermore, the performances are compared with three different existing methods such as OAP, FBM and NRZ-OOK-LOS. The BER value of the proposed system of scenario 1 is 0.0501 at 10 dB, which is less than that of the FBM technique.
A pair of tri-band multiple-input-multiple-output (MIMO) antennas with high isolation is investigated in this paper. The proposed antenna consists of two monopole antenna elements with an edge to edge spacing of 4 mm ...
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A pair of tri-band multiple-input-multiple-output (MIMO) antennas with high isolation is investigated in this paper. The proposed antenna consists of two monopole antenna elements with an edge to edge spacing of 4 mm (0.03 lambda(0) at 2.3 GHz). The monopole antenna element chose the bending line structure that can operate in tri-band and realize miniaturization. To achieve compact dimension and high isolation, symmetrical distribution layout is adopted to decouple the low frequency band, the U-shaped neutralization line (NL) contacting with two microstrip lines, and it can to improve the isolation in high frequency band, and the inverted U-shaped NL contacting with two radiation patch can decoupling in the middle frequency band. And then study the envelope correlation coefficient is lower, and the radiation pattern in operation bands is quasi-omnidirectional. It indicates that the antenna has obtained a satisfactory diversity performance within the whole operation bands which can be a good candidate for some portable MIMO applications.
multipleinputmultipleoutput(MEVIO) system is a new antenna technology in wireless communications. It has several antennas in both transmitting and receiving end and itis a frequency selective for multiple path char...
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ISBN:
(纸本)9781728146850
multipleinputmultipleoutput(MEVIO) system is a new antenna technology in wireless communications. It has several antennas in both transmitting and receiving end and itis a frequency selective for multiple path characteristics. Orthogonal-Frequency-Division-multiplexing is used to getting higher data rates in wireless communication systems. MIMO with OFDM system is used for converting the frequency selection channels into a parallel combination of frequency flat sub-channels. Due to the atmospheric conditions, some noises such as AWGN are added in the channels. So the system performance will be degraded. To enhance the reliability of the MIMO-OFDM system uses STBC scheme. Here to minimize the BER by allocating the power at transmitter using Particle-Swarm-Optimization (PSO) algorithm. The allocation of power at transmitting end and pilot tones optimization mainly depends on the diagonal matrix which is from the QR-decomposition of the channel matrix. The system performances of the proposed method are analyzed in terms of bit error rate and signal to noise ratio.
This paper investigates two typical frequency-domain turbo equalization (FDTE) schemes, i.e., frequency-domain equalization (FDE) with parallel interference cancelation (FDE-PIC) and FDE with frequency-domain decision...
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This paper investigates two typical frequency-domain turbo equalization (FDTE) schemes, i.e., frequency-domain equalization (FDE) with parallel interference cancelation (FDE-PIC) and FDE with frequency-domain decision feedback (FDE-FDDF) in single-carrier (SC) multiple-input-multiple-output (MIMO) systems. These two FDTE schemes are proven to be equivalent under the condition that we derived. We discover that the covariance matrix of the low-complexity FDE-PIC scheme and the correlation matrix of the FDE-FDDF scheme satisfy a unique relationship for constant-modulus modulations, and the original FDE-FDDF scheme suffers numerical instability for non-constant-modulus modulations because the estimation of the correlation matrices leads to the inversion of ill-conditioned matrices. By proposing a new estimation method of the correlation matrices, we guarantee that the non-constant-modulus FDE-FDDF scheme is numerically stable and that the relationship between these two FDTE schemes holds for both constant-modulus and non-constant-modulus modulations. Furthermore, we prove that the FDE-PIC and FDE-FDDF schemes are equivalent under this relationship. The equivalence of these two FDTE schemes is also verified through numerical simulations in terms of bit error rate (BER) at each turbo iteration and the estimation of the correlation matrices.
In this study, the design of a superimposed training (ST) for an interference-limited spatially correlated multiple-input-multiple-output (MIMO) system is addressed and a closed-form solution for designing the trainin...
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In this study, the design of a superimposed training (ST) for an interference-limited spatially correlated multiple-input-multiple-output (MIMO) system is addressed and a closed-form solution for designing the training signal is proposed in a sub-optimal way. Earlier papers have considered noise limited MIMO systems. The authors also propose random/orthogonal variable spread factor (OVSF) codes as a choice for the ST signal. The mean-squared error of the channel estimate and symbol error rate performances are obtained through simulation. Considering the power allocation issue between the data and training symbols, a sub-optimal average training power that maximises the lower bound on the effective signal-to-interference ratio is also proposed. Simulation results show that the bit error rate performance of the ST is indistinguishable from the OVSF/random ST sequence.
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