Multiple-input Multiple-output Applications Research Articles

Latency and Residual Energy Analysis of MIMO Heterogeneous Wireless Sensor Networks

Energy-constrained Wireless Sensor Networks (WSNs) have garnered significant research interest in recent years. Multiple-Input Multiple-Output (MIMO), or Cooperative MIMO, represents a specialized application of MIMO technology within WSNs. This approach operates effectively, especially in challenging and resource-constrained environments. By facilitating collaboration among sensor nodes, Cooperative MIMO enhances reliability, coverage, and energy efficiency in WSN deployments. Consequently, MIMO finds application in diverse WSN scenarios, spanning environmental monitoring, industrial automation, and healthcare applications. This research paper presents a comparative performance analysis of MIMO wireless sensor networks and traditional wireless sensor networks without MIMO using Network Simulator NS2.35 for analysis of End to End Delay for packet transmission and Residual energy of nodes. The research work shows application of MIMO in Wireless Sensor Networks with considerable improvements in Quality of Service parameters which is achieved through Spatial Multiplexing and Diversity Gain. MIMO enables multiple spatial streams, allowing several data streams to be transmitted simultaneously on the same channel. This increases the overall throughput as multiple sensors can transmit their data concurrently without interference. MIMO systems also provide diversity gain by transmitting multiple copies of the same data over different antennas which helps in mitigating the effects of fading and interference, resulting in a more reliable and higher-throughput communication link as compared to a SISO channel. Another advantage of employing MIMO in WSN is reduction in End-to-End delays in data transmission. Last but not the least, MIMO can be configured to optimize the power consumption of individual sensors by adjusting the number of antennas used and transmission power levels based on channel conditions. Hence, MIMO can help to extend the network's lifetime by conserving energy in resource-constrained sensor nodes by preservation of Residual Energy.

DESIGN OF HIGHLY ISOLATED UWB MIMO ANTENNA USING STUBS BETWEEN GROUND PLANES

This study introduces an in-depth analysis and evaluation of a novel High-Isolation Ultra-Wideband (UWB) Multiple Input Multiple Output (MIMO)antenna design featuring the integration of Stubs between ground planes.The objective is to develop an antenna system capable of achieving high isolation between closely spaced antenna elements for MIMO applications while maintaining a wide operating bandwidth. The proposed antenna is composed of four slot antenna elements with a common rhombic slot, each fed by a microstrip-fed line to greatly reduce the overall size of the antenna.It has a compact size of (34 x 34 x 1.6 mm3).The wide frequency range of Ultra-wide band lies in the range of 3.1 to 10.6 GHz and wide channel bandwidths of 500 MHz.The combination of ultra-wideband multiple-input and multiple-output(UWB MIMO) technology has high transmission rate,good communication quality and large channel capacity.Investigation will be done with respect to correlation parameter coefficients,radiation characteristics,efficiency,realized gain and the active reflection coefficient. In essence,the Highly Isolated MIMO Antenna marks a significant stride in antenna technology and in the field of wireless communication.CST(Computer Simulation Technology) is used to design the proposed antenna. Keywords-Antenna,Isolation,UWB,MIMO,Stubs,S-Parameter Results.

Design and verification of an umbrella shaped narrow band - UWB antenna pair for MIMO applications using characteristic mode analysis

Using characteristic mode analysis (CMA), a pair of ultra-wideband (UWB) and narrow band antennas is made. The Multiple Input Multiple Output (MIMO) configuration incorporates a circular monopole to attain UWB functionality, while an umbrella-shaped element generates the narrowband operation. The two radiators are symmetrically positioned to accomplish space diversity. Distinct sizes of small electromagnetic band gap cells separate the two radiators. The MIMO structure has dimensions of 40×40×1.6 mm3 (0.32λo×0.32λo×0.12 λo) and improved isolation is accomplished by adding a T-shaped stub to the ground plane. The exceptional bandwidth of 11.6 GHz offered by the Circular-pot UWB antenna covers a frequency range from 2.4 GHz to 14 GHz. The antenna demonstrates favorable MIMO performance, featuring a gain of 4.9dBi, isolation exceeding 23 dB. The diversity characteristics encompass an enveloped correlation coefficient (ECC) of under 0.0012, a diversity gain (DG) approaching 10 dB, a channel capacity loss of 0.28 b/s/Hz, and a mean effective gain (MEG) measuring -3.3 dB. A favorable agreement between the tested and simulated results.

Miniaturized Multi-band Millimeter-Wave Vivaldi Antenna with Performance Optimization at 28 GHz for 5G MIMO Applications

A novel design for Vivaldi antenna is introduced to operate in more than one frequency band in the millimeter-wave spectrum range with high gain. The proposed Vivaldi antenna is planar and printed on both sides of Rogers 3003C flexible substrate. A parasitic annular ring is added to each arm of the Vivaldi antenna to adjust the impedance matching and maximize the gain. The dimensions of the antenna are optimized using the CST microwave simulator to obtain the best impedance matching bandwidths and highest gain in a compact-size antenna. The 28-GHz band is then selected due to its importance to enhance the gain and improve the operating bandwidth for the 5G applications. A gain of 10 dBi and bandwidth of 6.1 GHz are obtained at 28 GHz. A multiple-input multiple-output (MIMO) antenna system is then designed for pattern diversity for the fifth-generation mobile applications. The performance of the MIMO system is evaluated regarding the envelope correlation coefficient and the diversity gain showing good results. The optimized antenna is fabricated and its return loss and radiation patterns are measured showing good consent between the simulations and the practical work. The MIMO antenna system is also fabricated, and its performance is measured regarding the reflection and coupling coefficients showing good agreement between the measurements and simulations.

Four‐port MIMO Vivaldi antenna for access points

AbstractIn this article, a 4‐port multiple input, multiple output (MIMO) antenna array is presented, based on a Vivaldi design for nonplanar applications like access points above 6 GHz. The antenna is configured with four Vivaldi antennas arranged orthogonally, one to each other, to increase the electromagnetic isolation among elements. The Vivaldi element is fed with a microstrip with an integrated balun in only one arm, and each arm is set in an antipodal position to the other, giving an easy‐to‐design and build prototype, with no complicated feeding techniques. Each antenna plane has dimensions of 90 × 40 mm2. The array presents a bandwidth from 5.3 GHz to beyond 20 GHz, with electromagnetic isolation above 20 dB, an envelope correlation coefficient below 0.001 for the entire bandwidth, giving a diversity gain around 20 dB, and a total active reflection coefficient below −10 dB from 7 to 20 dB, fulfilling the metrics for MIMO applications.

SMALL-SCALE MIMO ANTENNA WITH HIGH ISOLATION FOR 5G COMMUNICATION

This manuscript describes two- and three-element small-scale multiple-input multiple-output (MIMO) antenna configurations for 5G communications ranging from 23.5 to 28.6 GHz. Modern device antennas have two essential features: isolation and a larger bandwidth. In this regard, firstly a single element antenna has been designed using quarter wavelength impedance transformer and semi-circular loaded patch along with defected ground structure. Furthermore, two single-element antennas are placed orthonormal to each other having quarter wavelength distance from the center of the single-element antenna. To increase the bandwidth and isolation, additionally a rectangular patch and strip isolate from ground. This structural change alters the current path, improving the impedance matching and isolation of the two-element MIMO antenna configuration. After that the three-element MIMO configuration was formed by placing two single-element antennas orthogonally at quarter wavelength from the center of the single-element antenna. The total size of two- and three-element MIMO antenna is 15 × 11 × 1.6 mm and 20 × 11 × 1.6 mm, respectively. The proposed MIMO antennas provide isolation of more than 21 dB and gain more than 25 dB throughout the working band. MIMO diversity features function reasonably well, with an envelope correlation coefficient of less than 0.002 and diversity gain of 10. Proposed antennas can be a good candidate for MIMO applications in the 5G communication frequency range 2 (FR2), 28 GHz bands.

Designing Eight-port Antenna Array for Multi-Band MIMO Applications in 5G Smartphones

This article introduces a dual-functional low-profile compact multiple input multiple output (MIMO) antenna array for multi-band communication in 5G smartphones. The proposed eight elements of the antenna array form two different 4×4 MIMO systems. The first four elements are placed at the four mobile corners and operate in a single band of 3.445-3.885 GHz for 5G n77 and n78 applications. The other system, in which four antennas are positioned in the middle of the terminal board, supports two wide bands of 1.684-2.300 GHz and 4.432-5.638 for n2, n3, n39, n65, n66, n79, and WLAN applications. The second iteration of a modified Peano-type fractal geometry served as the design foundation for the proposed antenna element. The system's ground plane design is based on self-isolated and spatial diversity methods. The single-band MIMO system's isolation is better than 23 dB. In the dual-band MIMO system that is based on self-isolation, isolation equals approximately 16 dB in the higher band and 10 dB in the lower band. To evaluate performance, radiation-related and total antenna efficiencies, scattering parameters and gains were investigated. Additionally, ECCs have been considered to evaluate MIMO performance. According to the results, such design constitutes a valuable option for MIMO applications in 5G smartphones.

High isolation frequency-reconfigurable UWB-MIMO antenna with on-demand WiMAX band elimination

Abstract In this article, a planar dual-element frequency reconfigurable multiple-input multiple-output (MIMO) antenna for ultra-wideband (UWB) applications is studied. The frequency band can be switched between UWB operation and single band rejected UWB performance using a pair of PIN diodes in the MIMO configuration. The presented antenna is comprised of two similar slotted circular radiators, having tapered microstrip feedlines and separate partial ground planes. An RT/Duroid 5880 substrate with size 54 × 54 mm2 is used for the design purpose. Rotational symmetry between the radiators and diagonally oriented t-shaped decoupling structure behind the substrate have been utilized for high isolation purpose. The designed MIMO antenna exhibits UWB performance in mode 1. In other mode, the antenna operates in the frequency range 2.46–10.44 GHz with Worldwide Interoperability for Microwave Access (WiMAX) band rejection. Thus, the MIMO antenna exhibits on-demand single band rejection behavior depending on the switching conditions of the diodes. The measured isolation is greater than −20 dB in both the modes. The presented MIMO configuration possesses compact and planar geometry with high gain, good isolation, ultrawideband performance with reconfigurable band elimination, high efficiency and efficient diversity performance parameters. The suggested antenna is a good choice to be utilized for portable UWB MIMO applications.

Integrated Waveform Design Based on UAV MIMO Joint Radar Communication

The problem of orthogonal waveform construction in multiple input/multiple output (MIMO) radar communication integration greatly limits the realization of integration technology. In the unmanned aerial vehicle (UAV) MIMO antenna scenario, an orthogonal integrated waveform suitable for a MIMO antenna is designed using a sub−LFM−BPSK waveform combined with a chaotic spread spectrum code. After spread spectrum processing, each MIMO antenna transmits different communication data for orthogonal spread spectrum processing, which is suitable for the omnidirectional detection of MIMO application scenarios; moreover, the closed-form expressions of the integrated orthogonal waveform under certain constraints are derived. Finally, the simulation proves that the integrated orthogonal waveform set in the UAV MIMO scenario has excellent radar detection and communication capabilities.

Multiband Band and Dual Diversity Eight-Element MIMO Microstrip Antenna for Wireless Applications

This paper presents the design and performance analysis of multiband dual diversity 8-element multiple-input multiple-output (MIMO) antenna at 2.45/3.5/5.2/6 GHz. The proposed antenna was designed on a Flame Resistant (FR-4) substrate having a dielectric constant of 4.4 , dimensions of . The antenna was simulated and analyzed using Computer Simulation Studio (CST Studio). Results obtained from simulation showed that the 8-element MIMO antenna achieved a combined bandwidth of 908.68 MHz representing 34.51% of the fractional bandwidth. Broadside radiation pattern was observed across the three frequency bands in both E- and H-plane with average main lobe magnitude of 7.8 dBi. Furthermore, proposed antenna achieved consistent Envelop Correlation Coefficient (ECC) and Diversity Gain (DG) values of 0.0008 and 9.999 as well as Port-to-port isolation of 27 dB across all frequencies considered. Also, an antenna gain of 8.58 dB was achieved at a frequency of 6 GHz. The gain, isolation, DG and ECC between adjacent ports as well as the loss in capacity were within the standard margins, making the antenna structure suitable for MIMO applications.

Compact four elements SUB-6 GHz MIMO antenna for 5G applications

This work proposes a four elements sub-6 GHz multiple-input multiple-output (MIMO) antenna to operate within a frequency range of 1.6–4.4 GHz to serve 5G new radio (NR) n77 (3.3–4.2 GHz) and n78 (3.3–3.80 GHz) bands. The antenna elements are orthogonally placed to increase isolation. Defected ground structure and parasitic elements are used to reduce mutual coupling. The suggested antenna has been designed over FR-4 substrate on high frequency structure simulator software. The overall size of the antenna is 40 mm × 40 mm × 1.6 mm. The dimension of each element is 16.2 mm × 14.3 mm × 1.6 mm. An “EH” slot into the radiating element and protruded stubs are incorporated to improve bandwidth and impedance matching. The overall characteristics of the antenna is found to be better than some of the recently reported works making it a potential candidate for MIMO applications.

Self‐decoupling coupled‐fed patch antennas for 5G multiple‐input multiple‐output applications

AbstractSelf‐decoupling coupled‐fed patch antennas are designed in this letter. The self‐decoupling mechanism is based on the weak‐field region formed by the T‐shaped probe feed and the radiating patch of the antenna element itself. When another identical antenna element is placed in the weak‐field region, high isolation between the two elements can be achieved without adding extra decoupling structures. To validate the decoupling mechanism, a dual‐element antenna array is initially built and an isolation level of better than 30 dB is achieved over the impedance band of 3.3–3.66 GHz with an element spacing of 0.53λ0. Next, a four‐element multiple‐input multiple‐output (MIMO) linear antenna array is presented to further verify the decoupling method and good isolation performance is also obtained, which demonstrates that the proposed designs are good candidates for 5G MIMO applications.

Miniaturized six‐ring elliptical monopole‐based MIMO antenna for ultrawideband applications

SummaryThis paper proposes a miniature two‐element Multiple Input Multiple Output (MIMO) antenna dedicated to UWB applications. The proposed MIMO design has a very low profile of 30 × 20 × 1.6 mm3. The proposed antenna is carefully designed and optimized using HFSS simulation software. As a proof of concept, the proposed design is realized and experimentally tested for MIMO applications. The proposed structure, printed on an FR4 substrate, comprises two symmetrical elliptical conductive patches on the upper side and a modified ground plane on the lower one. Each radiating element includes six elliptical rings. The modified ground plane consists of a T‐shaped strip and two semielliptical slots etched opposite the feed line. All the parameters of the design are carefully optimized to achieve an ultrawide bandwidth antenna spanning from (136.08%) 3.1 to 16.3 GHz. The results are discussed and analyzed in terms of bandwidth, gain, efficiency, radiation pattern, diversity gain, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and mean effective gain (MEG). All simulated results are found to be in good accordance with experiments. The design reveals attractive features for UWB applications. A good isolation (17 dB) between the two radiators is achieved despite the close proximity using the suggested ground plane geometry.

Mutual coupling reduction in a textile ultra-wide band MIMO antenna

This paper presents a mutual coupling reduction technique in a textile ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna system implemented on a textile substrate. The compact textile UWB MIMO antenna consists of two patch antennas implemented on a felt textile substrate. The compact size and close placement of the antennas in a MIMO system cause higher mutual coupling which deteriorates the performance of the communication systems. To minimize the mutual coupling, Parasitic Elements and Defected Ground Structures are used in the designed textile UWB MIMO antenna. The MIMO antenna performed very well over almost the whole UWB frequencies ranging from 3.29 GHz to 13.3 GHz. The simulated and the measured parameters showed a good impedance matching with an impedance bandwidth of 133.4%. The results showed an improvement of 20 dB isolation at certain frequencies without impacting the reflection coefficient S11 and the antenna impedance bandwidth. The MIMO antenna has good diversity performance parameters in terms of Envelope Correlation Coefficient (ECC), Diversity Gain, Mean Effective Gain (MEG) and radiation pattern and the results indicate that the textile antenna is suitable for UWB MIMO applications. The overall size of the antenna is 30x60 mm2. Fully embroidered structure provides freedom of movement and comfort, so it is a good fit for Wireless Body Area Network applications.

Four ports MIMO printed antenna with high isolation for UWB and X-band systems

AbstractIn this work, a compact size 4 ports multiple input multiple output (MIMO) slot antenna with the connected ground for Ultra-Wide Band (UWB) and X band applications is introduced and discussed. The single antenna is a cross-shaped slot antenna in the ground plane and a 50 Ω microstrip line with a small L-stub is used to feed the antenna on the other side. The suggested MIMO antenna has four identical elements arranged to be orthogonal to each other to enhance the MIMO system performance. The antenna elements are connected with a small strip to compose the proposed connected ground antennas. The suggested MIMO antenna has an overall size of 47 mm × 47 mm. The antenna has tested and simulated bandwidth with S11 < −10 dB extended from 4– 14 GHz and has isolation greater than 20 dB between ports without utilizing the decoupling elements and with good consistency between results. The MIMO antenna has peak gain and efficiency, envelope correlation coefficient, diversity gain, and channel capacity loss of 5.6 dBi and 80%, <5 × 10–3, 10 dB, and <0.4 bit/s/Hz, respectively which prove that our antenna can be suggested for the UWB MIMO applications.

Unimodular Perfect and Nearly Perfect Sequences: a Variation of Björck’s Scheme

Constant Amplitude (CA), Zero Auto Correlation (ZAC) sequences (or CAZAC sequences, aka perfect sequences) have numerous applications. We generalize the CAZAC notion to what we term as CASAC by permitting small autocorrelations (SAC). We extend Björck’s classification result of two-valued CAZAC sequences by providing a complete classification of all almost 2-valued (i.e., two-valued except for the first position which uses a third value) CASAC sequences. While Björck’s original work dealt only with primes p, we extend his ideas to any abelian group of order <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$v\equiv 1\pmod {4}$ </tex-math></inline-formula> , as opposed to restricting just to the prime fields GF(p). Björck sequences have better ambiguity function than Zadoff-Chu sequences, making them suitable for radar and communications applications in the presence of high Doppler shifts. In fact, the discrete narrow band ambiguity function has an optimal bound in case of Björck sequences (as opposed to Gauss sequences). A one-parameter infinite family of CASAC we construct would have applications in Multiple-Input Multiple-Output (MIMO) areas. Toward MIMO applications, we introduce a performance measure we term as cross merit factor to study cross correlation behavior, generalizing the well-known notion of Golay Merit Factor (GMF).

A Compact Wideband Antenna With Suppressed Mutual Coupling for 5G MIMO Applications

A novel miniaturized wideband dual-polarized antenna, based on cross magnetic dipoles and a backed cavity, is proposed in this letter for multiple-input–multiple-output (MIMO) applications. The dipoles with exponential curvature edges deliver inherent wideband character to the radiator. Four parasitic resonators are introduced to miniaturize the top radiator's conducting area and lower the Q-factor of the whole structure, enhancing the antenna's impedance matching. Different from conventional direct-fed cross-dipole antennas, a wideband hybrid ring coupler is applied to excite the two dipoles simultaneously in-phase/out-of-phase to generate the ±45° polarization. The dimension of the proposed antenna is 42.5 mm × 42.5 mm × 18 mm, which is only 0.48 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_L</i> × 0.48 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_L</i> × 0.2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_L</i> at the frequency of 3.4 GHz. The corresponding MIMO array is studied, showing a low mutual coupling and envelope correlation coefficient level across the band, and an outperforming front-back-ratio performance. The antenna is prototyped and measured. The measurement results agree with those of the simulations well .

An Electromagnetic Information Theory Based Model for Efficient Characterization of MIMO Systems in Complex Space

It is the pursuit of a multiple-input-multiple-output (MIMO) system to approach and even break the limit of channel capacity. However, it is always a big challenge to efficiently characterize the MIMO systems in complex space and get better propagation performance than the conventional MIMO systems considering only free space, which is important for guiding the power and phase allocation of antenna units. In this manuscript, an Electromagnetic-Information-Theory (EMIT) based model is developed for efficient characterization of MIMO systems in complex space. The group-T-matrix-based multiple scattering fast algorithm, the mode-decomposition-based characterization method, and their joint theoretical framework in complex space are discussed. Firstly, key informatics parameters in free electromagnetic space based on a dyadic Green's function are derived. Next, a novel group-T-matrix-based multiple scattering fast algorithm is developed to describe a representative inhomogeneous electromagnetic space. All the analytical results are validated by simulations. In addition, the complete form of the EMIT-based model is proposed to derive the informatics parameters frequently used in electromagnetic propagation, through integrating the mode analysis method with the dyadic Green's function matrix. Finally, as a proof-or-concept, microwave anechoic chamber measurements of a cylindrical array is performed, demonstrating the effectiveness of the EMIT-based model. Meanwhile, a case of image transmission with limited power is presented to illustrate how to use this EMIT-based model to guide the power and phase allocation of antenna units for real MIMO applications.

LoS MIMO transmission for LEO satellite communication systems

To provide global service with low latency, the broadband low earth orbits (LEO) satellite constellation based communication systems have become one of the focuses in academic and industry. To allow for wideband access for user links, the feeder link of LEO satellite is correspondingly required to support high throughput data communications. To this end, we propose to apply line-of-sight (LoS) multiple-input multiple-output (MIMO) transmission for the feeder link to achieve spatial multiplexing by optimizing the antenna arrangement. Unlike the LoS MIMO applications for static scenarios, the movement of LEO satellites make it impractical to adjust the optimal antenna separation for all possible satellite positions. To address this issue, we propose to design the antenna placement to maximize the ergodic channel capacity during the visible region of the ground station. We first derive the closed-form probability distribution of the satellite trajectory in visible region. Based on which the ergodic channel capacity can be then calculated numerically. The antenna placement can be further optimized to maximize the ergodic channel capacity. Numerical results verify the derived probability distribution of the satellite trajectory, and show that the proposed LoS MIMO scheme can significantly increase the ergodic channel capacity compared with the existing SISO one.

High-Isolation wideband MIMO antenna with offset T-Shaped slots for 5G/WLAN applications

A broadband multiple-input multiple-output (MIMO) antenna with high isolation operating in 3.14–5.42 GHz (2.28 GHz, 53.3%) is proposed for 5G smartphones. An offset T-shaped slot with dual functions is employed to improve the bandwidth of one antenna element and enhance the isolation. Then, the double L-shaped stubs are loaded to improve the impedance matching of the other antenna in the MIMO antenna. Finally, the 2 × 2 MIMO antenna is constructed by four T-shaped monopole antennas, two double L-shaped stubs, and two offset T-shaped slots. The proposed MIMO antenna is first simulated and then experimentally tested with a good agreement. High isolation of greater than 15 dB, high antenna efficiency of more than 54%, and low envelope correlation coefficient (ECC) of smaller than 0.08 are realized within 3.14–5.42 GHz. These good performances indicate that the proposed antenna can be applied for MIMO applications in smartphones.