Multiple-input And Multiple-output Antenna Research Articles

Switchable Long-Term Evolution/ Wireless Wide Area Network/ Wireless Local Area Network Multiple-Input and Multiple-Output Antenna System for Laptop Computers

This paper introduces a multiple-input and multiple-output (MIMO) antenna system for deployment in the closed hinge slot region of notebook computers for long-term evolution (LTE)/wireless wide area network (WWAN)/wireless local area network (WLAN) applications. This antenna system was placed in the closed hinge slot region formed by the full metal cover, metal ground plate, and metal hinges. The MIMO antenna system, includes a main antenna (Ant 1), an auxiliary antenna (Ant 2), and an isolation element. The main and auxiliary antennas were integrated with the metal surrounding them and were used to excite several resonance modes of the closed hinge slot. Excellent antenna efficiency was achieved using the small antennas. Although Ant1 and Ant2 are only 25 mm $\times5$ mm in size, they could cover LTE/WWAN or WLAN operating bands by switching feed points in the same antenna pattern. The isolation element—a 10 mm $\times6$ mm metal sheet—was placed at the center of the closed hinge slot region, and enhanced isolation by more than 7 dB. The isolation levels exceeded 18 dB for LTE700/2300/2500 bands and 15 dB for 2.4/5.2/5.8 GHz WLAN bands.

Mô phỏng kênh truyền cho truyền thông MIMO quang không dây

Optical wireless communication is a potential candidate for 5th generation wireless communication systems (5G). The technology is orientated towards a commercial product called LiFi. This is technology for high-speed transmission and is especially effective in applications of Internet of Things (IoT). In order to evaluate the transmission quality of optical wireless systems, the wireless optical channel needs to be simulated through mathematical equations. The popular simulation methods of optical channel nowadays need to take many operations, particularly in the multiple-input and multiple-output (MIMO). In this paper, the response of the MIMO optical wireless communication and methods to reduce the number of operations in determining response of MIMO optical wireless channel were studied. Analysis results show that this method was reduced four times the complexity in 2x2 MIMO antenna configuration with reflection factor of 2.

A compact MIMO antenna system for WLAN with enhanced isolation

ABSTRACTA compact multiple‐input and multiple‐output (MIMO) monopole antenna system for WLAN (2.45 GHz) with enhanced isolation is proposed. The proposed MIMO antenna system consists of two identical monopole antenna elements operating at the same frequency of 2.45 GHz. In order to improve the isolation performance, each antenna element is individually placed on one side of the substrate. With meandered strips, the size of the proposed antenna system is dramatically decreased to 15.9 mm × 9 mm. The isolation between the two antenna elements exceeds 18.29 dB by employing the orthogonal polarization diversity technique and the physical isolation method. The 10 dB bandwidth of the proposed antenna system reaches 120 MHz, which is wide enough for the practical application. Measured results are in close agreement with the simulated ones. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1968–1973, 2016

Decoupling between ground radiation antennas with ground‐coupled loop‐type isolator for WLAN applications

A compact and easy to fabricate decoupling method is proposed to yield high isolation for the multiple-input and multiple-output (MIMO) ground radiation antenna (GradiAnt) system. The proposed MIMO antenna system is comprised of two symmetrical, closely spaced, loop-type (GradiAnts) with a ground-coupled loop-type isolator inserted between them. The isolator can be seen as a series resonant circuit which is connected with lumped components to control decoupling. In the proposed MIMO GradiAnt system, a coupling null is induced due to the ground-coupled isolator, which effectively can be used for isolation enhancement between two GradiAnts. Within WLAN band, a minimum 14 dB isolation with a peak value of 42 dB at 2.42 GHz is achieved. In this manuscript, the decoupling principle and controlling mechanisms are first explained, then the antenna performances and tuning mechanisms are discussed in detail. The simulation and the measurement of the MIMO antenna, including the scattering parameters, efficiency, radiation patterns, peak gains and envelope correlation coefficients are conducted to verify the performance of the proposed MIMO system.

Mm‐waves propagation measurements in underground mine using directional MIMO antennas

This study reveals the interests towards the use of directional (D)-multiple-input and multiple-output (MIMO) setup as a potential solution to overcome the severe propagation loss of inherent line of sight (LOS) mm-waves communications in underground mine. To show the advantages of the proposed D-MIMO, two separate measurement campaigns are assessed in a comparative way; the first uses a single-input single-output (SISO), while the second uses a 2 × 2 D-MIMO system. Furthermore, due to the unavoidable blockage of direct LOS in underground mines, the miner's shadowing effects (NLOS-MSE) are investigated. Thus, using both D-SISO and D-MIMO setup, the channel propagation characteristics are extracted and investigated with and without the presence of a miner completely blocking LOS. Under LOS, results show that, besides offering a reliable mm-waves link budget, D-MIMO restrains the average path loss (PL) by more than 4.7 dB, further suppresses the root mean square delay to 1.85 ns and offers an average capacity of 23.3 bits/s/Hz. As a miner completely blocks LOS, the proposed D-MIMO system has shown a greater signal ability to overcome the effects of a miner's body; NLOS-MSE compensation of about 4.3 dB and a capacity gain of 19.6 bits/s/Hz have been achieved over the conventional SISO system.

Compact dual band‐notched UWB mimo antenna with shared radiator

ABSTRACTAn ultrawideband (UWB) multiple input and multiple output (MIMO) antenna having shared radiator with dual band rejection characteristics is presented in this article. The proposed antenna is based on the concept of dual polarization. The antenna consists of two tapered CPW feeds printed on one side of the substrate and a circular shared radiator on the other side. The radiator is shared between two antenna elements. High isolation between the antenna elements is achieved by introducing a rectangular slot in the circular radiator and an inverted Y‐shaped stub on the ground plane at an angle of 45°. The proposed antenna rejects the WiMAX and wireless LAN band of frequencies using elliptical split ring slots in the shared radiator. The diversity performance of UWB MIMO antenna is also studied. The antenna is fabricated on FR4 substrate and has a small size of 41 mm × 41 mm. The simulated and measured results are in good agreement which demonstrate its potential use in UWB portable devices. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2886–2891, 2015

Analysis of MIMO antenna array based on 3D Von Mises Fisher distribution

A three-dimensional (3D) Von Mises Fisher (VMF) distribution model was derived in multiple-input and multiple-output (MIMO) antenna communication environment. The azimuth of arrival and elevation of arrival are distributed for VMF distribution instead of the uniform or other traditional distributions. In particular the MIMO uniform Y-shaped array (UYA) and the uniform circular array (UCA) antenna topology are considered at mobile station and base station. The developed spatial fading correlation of the VMF model is determined by parameters of the concentration parameter, antenna spacing, mean azimuth of arrival, mean elevation of arrival. Using the channel model, the effects of the concentration parameter and the mean elevation angle on the capacity of MIMO antenna systems was analyzed. It is shown that the mean elevation of arrival must be taken into account in 3D MIMO communication environment.

Design and optimization of LTE 1800 MIMO antenna.

A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide's outer shell. Isolation characteristics better than −15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz–1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi.

Asymmetric geometrical‐based statistical channel model and its multiple‐input and multiple‐output capacity

One of the fundamental research areas in wireless communications is the development of realistic models that can efficiently and accurately describe the wireless propagation channel. In this paper, the authors developed an asymmetric geometrical-based statistical channel model for mobile system and investigated the multiple-input and multiple-output (MIMO) receiving performance. This work was first in the asymmetric geometry literature to derive the closed-form explicit formulae for the time-of-arrival and the angle-of-arrival of the multi-paths, then the Doppler spectra. The channel model assumed that each multi-path component of the propagating signal undergoes only one bounce travelling from the base station (BS) to the mobile station (MS) and the scattering objects distributed around the BS, are assuming Gaussian and exponential spatial distribution models. Using the channel model, the authors first analysed the performance of MIMO antenna systems and Doppler spectra because of MS's motion.

Reduction of the Envelope Correlation Coefficient With Improved Total Efficiency for Mobile LTE MIMO Antenna Arrays: Mutual Scattering Mode

A mutual scattering mode is introduced in this paper. Utilizing this mode, the correlation of a lossy long-term evolution (LTE) multiple-input and multiple-output (MIMO) antenna array can be reduced efficiently, even down to zero, by increasing the Q factors of the MIMO antenna elements. In practice, the Q factors can be straight forwardly tuned through different input impedance matching. The zero correlation occurs at a Q factor higher than that resulting from the conjugate input impedance matching. On one hand, if the inter-element distance is larger than a certain distance (what we denominate as the Critical Distance), the total efficiency can also be improved in addition to reducing the correlation. On the other hand, when the inter-element distance is less than the critical distance, a reference MIMO antenna with high correlation and high total efficiency is obtained. This antenna can well be proposed for over-the-air (OTA) measurement applications. The introduced scattering mode is investigated for dual monopoles on a large lossy ground plane and for various mobile terminal MIMO antenna designs. A wideband MIMO antenna, with multiple resonances, covering the band 746-870 MHz is proposed with the envelope correlation coefficient and total efficiency less than 0.5 and higher than 50% (-3 dB), respectively. Measurements and simulations agree well for all the fabricated prototypes. The envelope correlations and the multiplexing efficiencies of the prototypes are also investigated in propagation channels with Gaussian distributed angle of arrivals.

Average Mutual Information Analysis of Multiple Input and Multiple Output System with Multihop Relaying in Wireless Communication System

Problem statement: Multiple Input and Multiple Output (MIMO) system with Multihop relaying techhnique is significant and active areas of wireless communication. In a rich scattering environment MIMO antenna system provides better channel capacity and data rates than single antenna systems. To provide high throughput, reliable transmission and broad coverage, wireless relaying techniques are essential in a variety of applications. In a cellular environment a relay can be used to overcome shadowing effect due to obstacles and multihop relaying can improve the throughput for mobiles suffering from poor signal to interference, noise ratio at the edge of a cell and reduce cell size to increase spectral efficiency. Approach: This study analyzes average mutual information of the Ricean channel for single hop Multiple Input Multiple Output (MIMO) system for different antenna configuation and dependence of capacity on the Rice factor for cellular system. The asymptotic capacity of multiuser two-hop MIMO system with Regularization Block Diagonalization (RBD) precoding techniques for Indepenent Identically Distributed (IID) channal and realistic Mobile to Mobile fading channel model was examined. In this realistic model, Non-Line-Sight (NLOS) propagation conditions are assumed from source mobile station to mobile relay and also from mobile relay to destination station. A non regenerative Amplify and Forward (AF) relay is used to optimize the capacity between the source and destination and also the evaluation was made for multiuser multi-hop relay system with correlated fading channel model using RBD precoding matrix. Results: The simulation results for average mutual information of single hop MIMO relay system for different antenna configuration with ricean channel model, ergodic sum mutual information for two hop relay system with RBD precoding technique and mutual information results for multiuser multihop relay system with correlated channel model was presented. Conclusion/Recommendations: Cellular systems generally operated at a fairly low SINR which can be increased on each hop by adding relays. Multiuser two hop relay system with RBD precoding for realistic mobile to mobile fading channel model is simulated and compared with IID channel model. Multiuser Multi-hop relay with optimal precoding and RBD precoding technique results were analyzed for correlated fading channel and found that capacity offered by RBD precoding scheme is better than other relaying systems.

MIMO SAR using Chirp Diverse Waveform for Wide-Swath Remote Sensing

Synthetic aperture radar (SAR) is a well-proven remote sensing technique; however, current single-antenna SAR systems cannot fulfill the increasing demands of future remote sensing in high-resolution and wide-swath imaging performance. This paper presents a scheme of multiple-input and multiple-output (MIMO) SAR using chirp diverse waveform for wide-swath remote sensing. This approach employs MIMO antenna configuration in elevation which is divided into multiple subpertures. In this way, multiple pairs of transmit-receive virtual beams directing to different subswathes are formed simultaneously. Equivalently a large swath is synthesized. The corresponding system scheme, chirp diverse waveform design, multi-beam forming algorithm and range ambiguity performance are investigated. A chirp-scaling-based image formation algorithm is presented to focus the MIMO SAR simulation data. Comprehensive numerical simulation examples are performed. It is shown that the proposed method enables the SAR systems to operate with high flexibility and reconfigurability which is particularly attractive for next generation remote sensing technique.

Design of a compact multiband internal antenna for mobile application

AbstractA compact multiband internal antenna for global system for mobile communication, digital cellular system, and wireless local area network services is proposed. The proposed antenna is composed of a multiple input and multiple output (MIMO) antenna and a dual‐band printed inverted F antenna. In particular, projected ground structure is adopted to improve isolation characteristic between the two elements of the MIMO antenna. The experimental results show that sufficient bandwidths, reasonable radiation patterns, and antenna gains are achieved for each frequency band. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2865–2868, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26413

Limited Feedback Beamforming Systems in Dual-Polarized MIMO Channel

Dual-polarized multiple-input and multiple-output (MIMO) antenna systems, where the antennas are grouped in pairs of orthogonally polarized antennas, are a spatiallyefficient alternative to single polarized MIMO antenna systems. A limited feedback beamforming technique is proposed for dualpolarized MIMO channels where the receiver has perfect channel knowledge but the transmitter only receives partial information regarding the channel instantiation. The system employs an effective signal-to-noise ratio (SNR) distortion minimizing codebook to convey channel state information (CSI) in the form of beamforming direction. By investigating the average SNR performance of this system, an upper bound on the average SNR distortion is found as a weighted sum of two beamforming distortion metrics. The distortion minimization problem is solved by designing a concatenated codebook. Finally, we propose a codebook switching scheme exploiting the cross-polar discrimination (XPD) statistics. Simulations show that the proposed codebook switching scheme with an XPD dependent concatenated codebook has the ability to adapt to dual-polarized channels.

Robust frequency offset estimation for pilot symbol assisted packet CDMA with MIMO antenna systems

We propose frequency offset estimation and combining techniques for pilot symbol assisted (PSA) packet downlink code-division multiple access (CDMA) with multiple-input and multiple-output (MIMO) antenna systems. Orthogonal Walsh codes are used for dedicated pilot symbols at the transmit antennas. The discrete Fourier transform (DFT)-based frequency offset estimation is used for simple implementation. In addition, simple interpolation is also used for resolution improvement of the DFT. When identical frequency offset is assumed, the frequency offset estimates for each single-input single-output (SISO) sub-stream (i.e., transmit/receive antenna pair) can be combined at the receiver. Simulation results show that the estimation and combining techniques proposed deliver improvement in the frequency offset estimation performance.