Multiple-input Multiple-output Applications Research Articles

Millimeter-Wave Transmission for Small-Cell Backhaul in Dense Urban Environment: a Solution Based on MIMO-OFDM and Space-Time Shift Keying (STSK)

Next generation wireless standards will exploit the wide bandwidth available at the millimeter-wave (mm-Wave) frequencies, in particular the $E$ -band (71–76 and 81–86 GHz). This large available bandwidth may be converted into multi-gigabit capacity, when efficient and computationally affordable transceivers are designed to cope with the constrained power budget, the clustered fading, and the high level of phase noise, which actually characterize mm-wave connections. In this paper, we propose a viable multiple-input multiple-output (MIMO) solution for high bit-rate transmission in the $E$ -band with application to small-cell backhaul based on space-time shift keying (STSK) and orthogonal frequency division multiplexing. STSK provides an efficient tradeoff between diversity and multiplexing without inter-channel interference and without the need for large antenna arrays. These features make STSK theoretically preferable over other throughput-oriented space-time coding techniques, namely, spatial multiplexing and spatial modulation, which were recently considered in the literature for mm-wave MIMO applications. In this paper, we consider the most significant channel impairments related to small-cell backhaul in dense urban environment, namely, the correlated fading with and without the presence the line-of-sight, the phase noise, the rain attenuation, and shadowing. In addition, we consider small-size MIMO systems ( $2 \times 2$ and $4 \times 4$ ), and low-cost base station equipments in the perspective of easily deployable small-cell network components. Comparative results, obtained by intensive simulations targeted at assessing link performance and coverage, have clearly shown the superior performance of STSK against counterpart techniques, although obtained at the cost of a somewhat reduced spectral efficiency.

Dual-Polarized On-Chip Antenna for 300 GHz Full-Duplex Communication System

This paper presents a novel design of compact orthogonally polarized on-chip antenna to realize 300 GHz full-duplex communication system with high isolation. It consists of a dipole antenna for horizontal polarization and a disk-loaded monopole antenna for vertical polarization. They are in good cross-polarization state with more than 90 dB of self-interference suppression and then can be used to achieve good isolation between transmitting and receiving antennas. In addition, two dual-polarized antennas have been adopted in two separated transceivers to study their isolation performance. Furthermore, this compact antenna only occupies an active area of 390 μm × 300 μm × 78 μm and can be used for multiple-input multiple-output application as well.

Dual-band pattern reconfigurable antenna for wireless MIMO applications

In this study, a dual-band pattern reconfigurable antenna is proposed for 2.4 and 5.8 GHz wireless multiple-input multiple-output (MIMO) applications. The proposed antenna comprises four pairs of active elements and parasitic elements loaded on PIN diodes. By switching PIN diodes, the parasitic element acts as a director or reflector, and the radiation patterns of the antenna are optimized. The antenna offers three modes with nine radiation beam patterns in a 5.8 GHz band. The measured peak gain of all the beam patterns ranges from 5.6 to 10.4 dBi. At a 2.4 GHz band, omnidirectional beam patterns with a measured peak gain of approximately 4.5 dBi are generated.

Compact modified ‘T’ slot circular patch quad band antenna for MIMO applications

Compact modified T-slot circular patch antenna for multiple input multiple output (MIMO) applications, which has good response for four operating frequency bands is developed. Here the design consists of a circular patch with a new slot loaded T- shape on one side of the substrate and a feeder line on the other side of the substrate. A shorting pin is located between the patch and the feeder line. This proposed antenna resonates at the frequencies of 2, 4.8, 5.4, and 6.2 GHz covering the S-band, C-band, and LTE applications. The independent tuning of frequency bands is achieved by varying the length of the slots. By independent tuning of frequency bands, the selection of interested frequency band is achieved. The single element with miniaturized size of 1.945λ × 1.945 λ (30 × 30 mm2) is achieved including the feed line. The antenna has been tested for MIMO applications. The measured envelope correlation coefficient between the two elements, which are spaced 0.139 λ is <0.1(low correlation) and mutual coupling is found to be in the range of −20 dB to −80 dB. The simulation and measurement results of reflection coefficient, mutual coupling, and radiation pattern are presented.

Compact band-notched UWB antenna for MIMO applications in portable wireless devices

A compact 5.5 GHz band-notched ultra-wideband (UWB) 2-element antenna with high isolation for multiple-input multiple-output (MIMO) portable wireless devices in wireless personal area network (WPAN) application is proposed. The MIMO antenna is designed for 3.1–10.6 GHz range on Neltec substrate with compact dimension of 43 × 20 mm2 and is tested experimentally. For the rejection band at 5.5 GHz, a slot of length 1.0 λ is etched into the radiator. Simple structure, i.e., receded steps at ground are used to improve isolation by 3 dB between two UWB antennas. The simulated and measured results show |S11| ≤ −10 dB and |S21| ≤ −20 dB in most of the frequency range excluding the reject band at 5.5 GHz in UWB range. The measured, simulated and calculated results show that the proposed UWB MIMO antenna is a good candidate for UWB MIMO systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1390–1394, 2016

Analysis and Design of SDF Architecture for MIMO Application

Background/Objectives: Fast Fourier transforms (FFT) has become ubiquitous in many engineering applications. FFT is one of the most employed blocks in many communications and signal processing systems. This paper aims in designing SDF architecture for efficient FFT algorithms. Methods/Statistical analysis: Efficient algorithms are being designed to improve the architecture of FFT. Higher Radix FFT algorithms have the traditional advantage of using less numbers of computational elements and are more suitable for calculating FFT of long data sequence. Findings: In designing SDF architecture for efficient FFT algorithms like Radix 2, Radix 4 and Radix 22, the designs are compared by performing simulations using VERILOG HDL and power analysis. The comparison includes the number of logic gates used by every architectures and their power dissipation using various devices. Trade-off between accuracy, speed, hardware complexity and power consumption should be made so as to choose the best fit architectures for the given application. Improvements/Applications: From the comparison results, best fit architecture is chosen and is implemented at the software level for the desired device for the Multiple Input Multiple Output (MIMO) application using Orthogonal Frequency Division Multiplexing (OFDM) employed in 4G technologies.

UWB MIMO antenna with common radiator

A compact printed 2 × 2 ultrawideband (UWB) multiple input multiple output (MIMO) antenna with a single circular patch as a common radiator for both the antenna elements is presented in this paper. A single circular patch is excited by two tapered CPW feeds for dual polarization. To improve the isolation between two ports, a rectangular slot of dimension L1 × W1 is created in the radiator. The UWB MIMO antenna has impedance bandwidth of 3–12 GHz with a isolation better than 17 dB between the two ports. The envelope correlation coefficient and the capacity loss are evaluated to ensure the good diversity performance of UWB MIMO antenna. The antenna has a compact size of 45 × 45 mm2 and is fabricated on low cost FR4 substrate and measured using Agilent VNA. The simulated and measured results show that the proposed UWB antenna is good candidate for UWB MIMO applications.

The Application of MIMO to Non-Orthogonal Multiple Access

This paper considers the application of multiple-input multiple-output (MIMO) techniques to non-orthogonal multiple access (NOMA) systems. A new design of precoding and detection matrices for MIMO-NOMA is proposed and its performance is analyzed for the case with a fixed set of power allocation coefficients. To further improve the performance gap between MIMO-NOMA and conventional orthogonal multiple access schemes, user pairing is applied to NOMA and its impact on the system performance is characterized. More sophisticated choices of power allocation coefficients are also proposed to meet various quality of service requirements. Finally computer simulation results are provided to facilitate the performance evaluation of MIMO-NOMA and also demonstrate the accuracy of the developed analytical results.

Dual-Band Textile MIMO Antenna Based on Substrate-Integrated Waveguide (SIW) Technology

A dual-band textile antenna for multiple-input–multiple-output (MIMO) applications, based on substrate-integrated waveguide (SIW) technology, is designed. The fundamental SIW cavity mode is designed to resonate at 2.4 GHz. Meanwhile, the second and third modes are modified and combined by careful placement of a via within the cavity to enable wideband coverage in the 5-GHz WLAN band. The simple antenna topology can be fabricated fully using textiles in a planar form, ensuring reliability and comfort. Numerical and experimental results indicate satisfactory antenna performance when worn on body in terms of impedance bandwidth, radiation efficiency, and specific absorption ratio (SAR). In order to validate its potential for MIMO applications, two elements of the proposed SIW antenna are arranged in six configurations to study the performance in terms of mutual coupling and envelope correlation. It is observed that the placement of the shorted edges of the two elements adjacent to each other produces the lowest mutual coupling and consequently the best envelope correlation.

Dual-band-notched antenna for UWB MIMO applications

In this report, a compact antenna system with dual-band-notched characteristics is proposed for ultra-wideband (UWB) multiple-input multiple-output (MIMO) applications. Two antenna elements are placed side by side and fed with matched microstrip lines on a substrate with an area of 35 × 30 mm2. Notched characteristics at WiMAX (3.4–3.6 GHz) and WLAN (5.725–5.825 GHz) have been achieved using complementary split ring resonator (SRR) slots etched in both the antenna elements. Electromagnetic isolation between the two elements close to each other is achieved using a ground T-stub and slots etched in the ground plane. Antenna system has been tested and measured results are close to the desired ones. Measured isolation >20 dB is obtained in most of the UWB bands. The proposed antenna system meets the requirements well for MIMO applications.

Four‐element quad‐band multiple‐input–multiple‐output antenna employing split‐ring resonator and inter‐digital capacitor

In this study, a novel four-element multiple-input–multiple-output (MIMO) antenna having quad-band characteristics is proposed. A coplanar waveguide-fed monopole is loaded with a split-ring resonator and an inter-digital capacitor to achieve miniaturisation and quad-band operation. These quad-band elements are arranged properly to implement a four-element MIMO configuration which provides both spatial and pattern diversities. The achieved isolation performance is better than 20 dB. Measurement results confirm that the proposed MIMO antenna operates at 1.95, 2.39, 2.64 and 3.27 GHz with impedance bandwidths of 2.66, 6.57, 8.8 and 4.09%, respectively. The proposed antenna exhibits quasi-monopolar radiation pattern and measured envelope correlation coefficient <0.01 is obtained in all the operating bands. The proposed antenna can be useful for MIMO applications in global system of mobile/Bluetooth/wireless local area network/worldwide interoperability for microwave access operating bands.

Novel ultra-compact two-dimensional waveguide-based metasurface for electromagnetic coupling reduction of microstrip antenna array

A novel ultracompact two-dimensional (2D) waveguide-based metasurface is proposed herein and applied for the first time to reduce mutual coupling in antenna array for multiple-input multiple-output applications. The unit cell of the proposed 2D waveguide-based metasurface is ultracompact (8.6 mm × 4.8 mm, equal to λ0/14.2 × λ0/25.5) mainly due to the symmetrical spiral lines etched on the ground. The metasurface exhibits a bandgap with two transmission zeros attributing to the negative permeability in the vicinity of magnetic resonance and the negative permittivity in the vicinity of electric resonance. Taking advantage of these two features, a microstrip antenna array is then designed, fabricated, and measured by embedding an 8 × 1 array of the well-engineered 2D waveguide-based metasurface elements between two closely spaced (9.2 mm, equal to λ0/13.3) H-plane coupled rectangular patches. There is good agreement between the simulated and measured results, indicating that the metasurface effectively reduces antenna mutual coupling by more than 11.18 dB and improves forward gain. The proposed compact structure has one of the highest reported decoupling efficiencies among similar periodic structures with comparable dimensions. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:789–794, 2015.

A novel eight ports dual band antenna array for 2.4/3.5 GHz MIMO applications

An eight ports multiple-input multiple-output (MIMO) patch antenna array operating at 2.4GHz and 3.5GHz band is presented in this paper, which can be used for the Long Term Evolution (LTE), Microwave Access (WiMAX) and the low frequency band of Wireless Fidelity (WiFi). The presented antenna is fabricated on a F4B-2 substrate (ɛr=2.65, tanδ=0.002), it consists of four coplanar E-shaped patches which are orthogonal to each other. Two feed ports are respectively located at two adjacent sides of each patch. Double symmetrical slots are etched out in each patch to improve the antenna bandwidth, a 46mm×33mm metal parasitic patch is placed above each patch to improve the gain. The maximum gain of the proposed antenna array is more than 8dB at 2.4GHz band and 9dB at 3.5GHz band respectively.

Open Source SDR Frontend and Measurements for 60-GHz Wireless Experimentation

This paper aims to make 60-GHz experimentation possible for a wider range of research groups. We do this by describing a low-cost front-end that can be used in combination with any baseband processing platform. We provide detailed instructions and software for connection with the USRP N200/N210, including general classes for controlling the board and example single-input single-output and 2 × 2 Multiple-Input Multiple Output applications. In addition, we provide measurements to assess the impact of phase noise and other hardware impairments in low-cost millimeter-wave systems for hybrid measurement and simulation studies. Finally, we also perform performance measurements on the hardware. All our materials, such as the hardware design, the software, and the measurements, are freely available.

Wideband Characteristic Mode Tracking Utilizing Far-Field Patterns

The Theory of Characteristic Modes provides a convenient tool for designing multi-antennas for multiple-input multiple-output applications, as it enables orthogonal radiation patterns to be excited in a given antenna structure. Moreover, the frequency behavior of the modes reveals interesting wideband properties of the structure. However, the tracking of characteristic modes over frequency remains a challenge, especially when differences between modes are limited to high currents in small regions of the structure. The common approach of tracking characteristic modes is through correlating the modal currents over frequency, this leads to multiple eigenvalues being mapped to the same eigencurrent. In this letter, we propose a new approach to track characteristic modes by means of cross correlating far-field patterns, which effectively eliminates the mode mapping ambiguity.

Design of planar inverted‐F antenna over uniplanar EBG structure for laptop mimo applications

ABSTRACTThree uniplanar shapes of electromagnetic band gap (EBG) structure as T‐shape, fractal shape, and interdigital capacitors are investigated for antenna applications. The proposed EBG shapes are etched on the ground plane of the planar inverted‐F antenna (PIFA) to improve the impedance bandwidth, reduce the antenna size, increase the gain, and improve radiation pattern. Next, two trapezoidal shaped slots are etched on the radiating plate of PIFA antenna to excite two resonant frequencies. The proposed antenna is designed to cover two narrow bands at GSM 1.8 GHz, upper WLAN 5.2 GHz and a wideband from 2.4 to 4 GHz. Effect of the laptop is investigated on the performance of the proposed antenna. Finally, the effect of these new EBG shapes on mutual coupling reduction between two pair of antennas is studied for multiple input multiple output application in laptop device. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:277–285, 2015

A reduced size dual port MIMO DRA with high isolation for 4G applications

© 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:495-501, 2015. © 2014 Wiley Periodicals, Inc.A dual-port reduced size multiple input multiple output (MIMO) Dielectric Resonator Antenna (DRA) has been studied and proposed. The MIMO antenna consists of a Rectangular Dielectric Resonator antenna, which is fed by two symmetrical feed lines for orthogonal mode excitation. The proposed antenna is suitable for operation over various long term evolution (LTE) bands. A measured bandwidth of 264 MHz for |S 11 | <-10dB and isolation of 18 dB at 1.8 GHz has been obtained. Besides, the Envelope Correlation Coefficient, Mean Effect Gain and Diversity Gain have been studied for the presented MIMO DRA using the S-parameters. Based on these results, it can be concluded that the proposed antenna can be a suitable candidate for MIMO applications.

RBFNN Variable Structure Controller for MIMO System and Application to Ship Rudder/Fin Joint Control

Aiming at a class of multiple-input multiple-output (MIMO) system with uncertainty, a sliding mode control algorithm based on neural network disturbance observer is designed and applied to ship yaw and roll joint stabilization. The nonlinear disturbance observer is finished by radial basis function neural network and with that a terminal sliding mode control algorithm is proposed. The asymptotic stability of closed-loop system is proved based on Lyapunov theorem. The proposed control law is applied to anti-roll control under simulative wave disturbances. Simulation results verified robustness and effectiveness of the suggested algorithm. A good anti-rolling effect is achieved and yaw angle is also reduced greatly with less mechanical loss.

A new design of triple‐band WLAN/WiMAX monopole antenna for multiple‐input/multiple‐output applications

ABSTRACTIn this manuscript, a new design of microstrip‐fed monopole antenna with meander‐line strips for wireless local area network (WLAN) and world‐wide interoperability microwave access (WiMAX) systems is proposed. The operating frequencies of the proposed antenna are 2.4/3.5/5.5 GHz, which covers the WLAN and WiMAX bands. The measured results of the proposed antenna show that the impedance bandwidths are from 2.01 to 2.67 GHz, 3.25 to 3.75 GHz, and 5 to 6 GHz. The presented antenna has a small size of 12 × 18 mm2. Various configurations of array of this antenna for multiple input‐multiple output (MIMO) application are also studied. It shows that the features of low profile, good return loss, and small mutual coupling are promising for MIMO applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2667–2671, 2014

Design and Evaluation of Pattern Reconfigurable Antennas for MIMO Applications

In recent years, reconfigurable antennas have been sought to improve the performance of multiple-input multiple-output (MIMO) wireless communication systems. Their ability to dynamically reconfigure their radiation pattern adds diversity in a manner that is not possible with fixed antennas. This paper investigates the performance benefits provided by pattern reconfigurable receiving antennas with uniform beam steering capability. Their potential performance is first estimated using simulations, and for the first time, the effect of uniform beam steering on MIMO system performance is evaluated in a real indoor channel using two electrically steerable passive array radiator (ESPAR) antennas. Performance comparison is made against a pair of monopole antennas using a hardware bit error rate (BER) test-bed that incorporates statistical spatial averaging in order to assess performance improvements in a more realistic way, and analyze the effect of antenna diversity on the overall system performance. The MIMO-ESPAR system reduces BER with certain pattern combinations and excels in capacity evaluations. The ESPAR antennas improve the spatially averaged channel capacity by as much as 37% at 10 dB transmit SNR, and gain an additional 1 bit/s/Hz in peak capacity at 10 dB receive SNR from diversity gain alone. These improvements make pattern reconfigurable antennas promising options in MIMO-related applications.