Mean Channel Capacity Research Articles

Mutual Coupling Reduction in Compact MIMO Antenna Operating on 28 GHz by Using Novel Decoupling Structure.

This article presents an antenna with compact and simple geometry and a low profile. Roger RT6002, with a 10 mm × 10 mm dimension, is utilized to engineer this work, offering a wideband and high gain. The antenna structure contains a patch of circular-shaped stubs and a circular stub and slot. These insertions are performed to improve the impedance bandwidth of the antenna. The antenna is investigated, and the results are analyzed in the commercially accessible electromagnetic (EM) software tool High Frequency Structure Simulator (HFSS). Afterwards, a two-port multiple-input-multiple-output (MIMO) antenna is engineered by orthogonalizing the second element to the first element. The antenna offers good value for mutual coupling of less than -20 dB. The decoupling structure or parasitic patch is placed between two MIMO elements for more refined mutual coupling of the proposed MIMO antenna. The resultant antenna offers mutual coupling of less than -32 dB. Moreover, other MIMO parameters like envelop correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL) are also studied to recommend antennas for future applications. The hardware model is fabricated and tested to validate the results, which resembles software-generated results. Moreover, the comparison of outcomes and other important parameters is performed using published work. The outcome of this proposed work is performed using already published work. The outcomes and comparison make the presented design the best option for future 5G devices.

Miniaturized and high gain circularly slotted 4×4 MIMO antenna with diversity performance analysis for 5G/Wi-Fi/WLAN wireless communication applications

A miniaturized with a high gain four port Multiple-Input Multiple-Output (MIMO) is presented in the manuscript. The presented design contains four radiating patch elements with a Defected Ground Structure (DGS). The shape of the radiating element is identified after the analysis of three stages. The design optimization is performed by changing the diameter of the circle loaded in the patch region and changing the length of the ground layer. The design is investigated for L, S, C, and X frequency band regions. The structure is designed using flame-retardant glass-reinforced epoxy laminate material (FR4) substrate material. The physical size of the four-port structure is 78x50 mm2. Three resonating frequency bands are observed at 2.02 GHz, 5.87 GHz and 11.19 GHz. The structure provides minimum return loss of −10.27 dB, −18.51 dB and −18.59 dB. The proposed design achieves a peak bandwidth of 3.94 GHz, and a maximum gain of 10.03 dBi, Various diversity parameters, including Total active reflection coefficient (TARC), Envelope Correlation Coefficient (ECC), mean effective gain (MEG), Diversity Gain (DG), and channel capacity loss (CCL), have been thoroughly analyzed. The measured and simulated outcomes are compared and analyzed. All performance indicators meet the allowed limits, demonstrating the suitability of the design for 5G, Wi-Fi and WLAN wireless communication applications.

A Numerical Investigation of Graphene-Based Hilbert-Shaped Multi-Band MIMO Antenna for the Terahertz Spectrum Applications.

We proposed the numerical investigation of Hilbert-shaped multiple-input multi-output (MIMO) with multi-band operation characteristics using graphene resonator material, which operates on the band of 1 to 30 THz of the frequency range. This numerical investigation of antenna structure was carried out for the multiple antenna types, consisting of graphene as a regular patch, Hilbert order 1, and Hilbert order 2 designs. This antenna is investigated for the multiple physical parameters, such as return loss, gain, bandwidth, radiation response, Envelope Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), Mean Effective Gain (MEG), Directivity Gain (DG), and Channel Capacity Loss (CCL). These variables are also determined to verify compatibility and the difficulties connected with communicating over a short distance. The THz MIMO antenna that was recommended offers strong isolation values in addition to an operational band. The maximum gain of ~10 dBi for the band of <15 THz and ~17 dBi for the band of the >15 THz frequency range of the proposed antenna structures. The proposed antennas are primarily operated in three bands over 1 to 30 THz of frequency. This work aims to create a brand new terahertz antenna structure capable of providing an extraordinarily wider bandwidth and high gain while keeping a typical compact antenna size suited for terahertz applications.

Transparent 2-Element 5G MIMO Antenna for Sub-6 GHz Applications

A dual-port transparent multiple-input multiple-output (MIMO) antenna resonating at sub-6 GHz 5G band is proposed by using patch/ground material as transparent conductive oxide (AgHT-8) and a transparent Plexiglas substrate. Two identical circular-shaped radiating elements fed by using a microstrip feedline are designed using the finite element method (FEM) based high-frequency structure simulator (HFSS) software. The effect of the isolation mechanism is discussed using two cases. In case 1, the two horizontally positioned elements are oriented in a similar direction with a separate ground plane, whereas in case 2, the elements are vertically placed facing opposite to each other with an allied ground. In both cases, the transparent antennas span over a −10 dB band of 4.65 to 4.97 GHz (300 MHz) with isolation greater than 15 dB among two elements. The diversity parameters are also analyzed for both the cases covering the correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL). The average gain and efficiency above 1 dBi and 45%, respectively with satisfactory MIMO diversity performance, makes the transparent MIMO antenna an appropriate choice for smart IoT devices working in the sub-6 GHz 5G band by mitigating the co-site location and visual clutter issues.

FOUR-ELEMENT MIMO ANTENNA WITH HIGH ISOLATION AND DIVERSITY PERFORMANCE FOR UWB APPLICATIONS

A four-element multiple-input multiple-output (MIMO) antenna for wireless ultra-wideband (UWB) applications is proposed in this study. The single-element antenna is derived by conducting several design evolutions. This fundamental antenna achieves an UWB impedance bandwidth with good positive gain across the operating frequency ranges. In the investigation of MIMO antennas, dual and four-element MIMO antennas with variable layouts are designed and analyzed according to their S parameters, gain, radiation pattern, and diversity performance findings. Thus, a four-element MIMO antenna operating in the frequency range of 3.5-11.2 GHz with &amp;#62; -20 dB isolation in the majority of the band is proposed. The diversity performances in terms of envelope correlation coefficient and diversity gain are less than 0.006 and greater than 9.9, respectively, while the mean effective gain (MEG) and channel capacity loss (CCL) are within acceptable ranges. The simulated findings agree well with the measured results.

A Compact Self-Isolated MIMO Antenna System for 5G Mobile Terminals

A compact self-isolated Multi Input Multi Output (MIMO) antenna array is presented for 5G mobile phone devices. The proposed antenna system is operating at the 3.5 GHz band (3400–3600 MHz) and consists of eight antenna elements placed along two side edges of a mobile device, which meets the current trend requirements of full-screen smartphone devices. Each antenna element is divided into two parts, a front part and back part. The front part consists of an I-shaped feeding line and a modified Hilbert fractal monopole antenna, whereas the back part is an L-shaped element shorted to the system ground by a 0.5 mm short stub. A desirable compactness can be obtained by utilizing the Hilbert space-filling property where the antenna element’s overall planar size printed on the side-edge frame is just (9.57 mm × 5.99 mm). The proposed MIMO antenna system has been simulated, analyzed, fabricated and tested. Based on the self-isolated property, good isolation (better than 15 dB) is attained without employing additional decoupling elements and/or isolation techniques, which increases system complexity and reduces the antenna efficiency. The scattering parameters, antenna efficiencies, antenna gains, and antenna radiation characteristics are investigated to assess the proposed antenna performance. For evaluating the proposed antenna array system performance, the Envelope Correlation Coefficients (ECCs), Mean Effective Gains (MEGs) and channel capacity are calculated. Desirable antenna and MIMO performances are evaluated to confirm the suitability of the proposed MIMO antenna system for 5G mobile terminals.

Design of an Integrated Sub-6 GHz and mmWave MIMO Antenna for 5G Handheld Devices

The reported work demonstrates the design and realization of an integrated mid-band (sub-6 GHz) and mmWave multiple input, multiple output (MIMO) antenna for 5G handheld devices. The proposed prototype consists of the two-port MIMO configuration of the mid-band antenna placed at the top and bottom of the substrate, while the 4-port mmWave MIMO antenna is placed sideways. The MIMO configuration at the top and bottom consists of a two-element array to achieve high gain at the mid-band spectrum, while the antennas placed sideways are optimized to cover the 5G-mmWave band spectrum. The overall dimensions of the board were selected the same as the of smartphones, i.e., 151 mm × 72 mm. The mid-band antenna has an operational bandwidth of 2.73 GHz, whereas the mmWave antenna has an impedance bandwidth of 3.85 GHz with a peak gain of 5.29 and 8.57 dBi, respectively. Furthermore, the design is analyzed for the various MIMO performance parameters; it was found that the proposed antennas offer high performance in terms of envelop correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG) and channel capacity loss (CCL) within operational range. A fabricated prototype was tested and measured results show strong agreement with predicted results. Moreover, the proposed work is compared with state-of-the-art work for the same applications to demonstrate its potential for targeted application.

A Modified OMP Algorithm with Reduced Feedback Overhead for Massive MIMO System

Objectives: Massive Multiple-Input and Multiple-Output (MIMO) is the optimum way to enhance the bandwidth issue, in which the feedback overhead is a challenging concern when tested with Frequency Division Duplex (FDD) systems. Conventional greedy search algorithms like Matching Pursuit (MP) and Orthogonal Matching Pursuit (OMP) are based on the prior knowledge of the signal sparsity, which enhances overhead. So, the objective of this study is to develop a method with low complexity channel estimation and reduced feedback overhead. Methods: The proposed method is based on the residual vector which is updated after iteration and a threshold-based approach is utilized to decide the stopping criteria thereby controlling the number of iterations. The evaluation parameters used in the experimental analysis are Normalized Mean Square Error and channel capacity. Findings: The proposed method improves the effectiveness in signal recovery and reconstruction along with signal sparsity it also reduces the complexity of the estimation process and limits the feedback. This results in a high data rate and can be used in a massive MIMO system to optimize the channel estimation. Novelty : The proposed model is independent of the sparsity in the input vector and improves the effectiveness of the signal recovery and reduces the feedback burden. The proposed method is suitable for a 5G massive MIMO systems. Keywords: Feedback overhead; CSI; OMP; Residue vector

Sub-6 GHz Dual-Band 8 × 8 MIMO Antenna for 5G Smartphones

In this letter, a dual-band 8x8 MIMO antenna that operates in the sub-6 GHz spectrum for future 5G multiple-input multiple-output (MIMO) smartphone applications is presented. The design consists of a fully grounded plane with closely spaced orthogonal pairs of antennas placed symmetrically along the long edges and on the corners of the smartphone. The orthogonal pairs are connected by a 7.8 mm short neutral line for mutual coupling reduction at both bands. Each antenna element consists of a folded monopole with dimensions 17.85 x 5mm2 and can operate in 3100-3850 MHz for the low band and 4800-6000 MHz for the high band ([S11] ˂ -10dB). The fabricated antenna prototype is tested and offers good performance in terms of Envelope Correlation Coefficient (ECC), Mean Effective Gain (MEG), total efficiency and channel capacity. Finally, the user effects on the antenna and the Specific Absorption Rate (SAR) are also presented.

Rectangular DR-based dual-band CP-MIMO antenna with inverted Z-shaped slot

ABSTRACT In this paper, a dual-band circular polarised (CP), Multiple Input Multiple Output (MIMO) antenna with bi-directional polarisation is presented. Designed antenna is operating at two frequency bands i.e. 5.4 GHz–6.2 GHz and 7.0 GHz–7.4 GHz. A rectangular dielectric resonator (DR) is excited by two ports for designing an MIMO antenna system. To generate the Circular polarisation, ground plane is modified by etching an inverted Z-shaped slot. The fundamental mode , and higher order mode , are generated in the antenna structure due to the specified geometry which excites the circular polarisation. 3-dB axial ratio (AR) bandwidth of 300 MHz (5.7 GHz–6.0 GHz) and 200 MHz (7.0 GHz–7.2 GHz) is obtained for the lower and upper bands, respectively. Maximum isolation is 19 dB, and 15 dB for the targeted bands have been achieved. S-parameters, gain and radiation pattern are measured to authenticate the simulated results. Envelope correlation, diversity gain, mean effective gain and channel capacity loss are calculated from the measured parameters; their values lie within the optimum range. Results show that antenna is suitable for WLAN 5.5/5.8 GHz and X-band downlink communication at 7.0 GHz.

Morphological Response to Discharge Reduction in a Partially Abandoned Channel of the Catawba River, North Carolina, USA

Examples of partial avulsion and river bifurcation around large stable islands make up a small but locally important portion of the total length of rivers in the Piedmont physiographic province of North Carolina (U.S.). Despite remaining ecologically significant, the partially abandoned (or “abandoning”) branches along such reaches have received less attention than the often dominant newly created branches. The existence of perennial flow through abandoning channels may be contingent upon their ability to rapidly adjust their morphologies to declining flows. In this paper we study the response of a partially abandoned channel of the upper Catawba River in North Carolina to major loss of flow following flood-induced partial avulsion in 1977. Human activities have strongly modified the floodplain in this area, assisting the avulsion and possibly influencing the natural erosion and sedimentation processes responsible for subsequent adjustments of the abandoning channel. Using a combination of downstream gaging data, flow estimation functions, channel mapping, and hydraulic geometry analyses, we assess the degree to which channel capacity reduction matches the amount of post-avulsion diminished discharge. Construction of fluvial sediment benches inset within the old single-thread channel has occurred along 83% of the channel's length, and most of these have crest elevations in the 1–2 yr flood stage range. Hydraulic geometry reconstructions indicate that length-weighted mean channel width, depth, and capacity deviate from predicted values by 36%, 18%, and 61%. Thus, channel cross-section dimensions for the abandoning channel appear substantially larger than predicted, a condition that is potentially discordant with a hypothetical necessity of rapid width adjustment for maintaining an open channel, depending on what constitutes a rapid rate of adjustment. Variables such as the morphology of the bifurcation node and load properties also influence the longevity of abandoning channels, and rates of adjustment or infilling can vary widely. Stratigraphic, pedogenic, and vegetative evidence together suggest that channel narrowing via inset bench formation has occurred gradually over at least two or more decades following initial flow loss. Comparisons with channel dimensions predicted from existing Piedmont regional curves show greater agreement, supporting the contention that Piedmont valley characteristics exercise at least as strong an influence on channel morphology as does the higher relief watershed topography and associated flow regime. The presence of perennial flow and active geomorphological processes in the abandoning channel indicates that it remains part of a dynamic and ecologically significant river reach, despite being currently designated as land in county land parcel records.

Super‐wideband multi‐input–multi‐output dielectric resonator antenna

A half-split inverted-frustum shaped two-port multi-input-multi-output (MIMO) dielectric resonator antenna is proposed with the ultra-wideband response. The antenna provides the impedance bandwidth of 132.69% (7 - 34.6 GHz) with each port. The MIMO performance parameters like envelope correlation coefficient, diversity gain, mean effective gain and channel capacity loss remain in the acceptable limits with the isolation more than 20 dB throughout the operating band. In addition, the antenna provides the peak gain ranging from 4 - 9.5 dBi at port-1 and 4 - 8 dBi at port-2.

Dual polarized triple‐band dielectric resonator based hybrid MIMO antenna for WLAN/WiMAX applications

AbstractIn this article, a dual polarized triple‐band dielectric resonator based hybrid multiple‐input multiple‐output (MIMO) antenna is presented. The proposed MIMO antenna is designed with the help of two cylindrical dielectric resonators along with two symmetrical modified Y‐shaped microstrip printed lines. Two metallic strips and a slot on the ground plane are used to enhance the isolation. A prototype of the proposed design is fabricated and tested to validate the simulation outcomes. The measured outcomes confirmed that the proposed antenna can be utilized in three different frequency bands such as 2.21–3.13, 3.40–3.92, and 5.30–6.10 GHz with fractional bandwidth of 34.45%, 14.2%, and 14%, respectively. The modified Y‐shaped printed line is used to obtain circular polarization in the upper frequency band with fractional axial ratio (AR) bandwidth of 4.18%. Besides, MIMO performance has also been examined in terms of diversity parameters like envelope correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL).

A compact dual port UWB-MIMO/diversity antenna for indoor application

A compact printed quadrant shaped monopole antenna is introduced in this paper as a good prospect for ultra wideband- multiple-input multiple-output (UWB-MIMO) system. The proposed MIMO antenna comprises two perpendicularly oriented monopoles to employ polarization diversity. An open circuit folded stub is extended from the ground plane of each radiating element to enhance the impedance bandwidth satisfying the UWB criteria. Two ‘L’ shaped slots are further etched on the radiator to provide good isolation performance between two radiators. The desirable radiator performances and diversity performances are ensured by simulation and/or measurement of the reflection coefficient, radiation pattern, realized peak gain, envelope correlation coefficient (ECC), diversity gain, mean effective gain (MEG) ratio and channel capacity loss (CCL). Results indicate that the proposed antenna exhibits 2.9–11 GHz 10 dB return loss bandwidth, mutual coupling &lt;−20 dB, ECC&lt;0.003, MEG ratio≈1, and CCL&lt;0.038 Bpsec/Hz, making it a good candidate for UWB and MIMO diversity application.

Eight‐port orthogonally dual‐polarised MIMO antennas using loop structures for 5G smartphone

An eight-port antenna array designed for future 5G 2.6 GHz band (2550-2650 MHz) for multi-input multi-output (MIMO) in the smartphone applications is presented. In order to enhance the port isolation and reduce correlation between antennas, square loop radiating strip with orthogonal polarisation is employed. The proposed antenna array is composed of four pairs of uniform antenna elements that are symmetrically placed at the four corners of the main board, and each antenna pair includes a communal square loop and two independently coupled feeding strips. By exciting the square loop from the two feeding strips, respectively, two orthogonally polarised waves are generated. Thus, four horizontally polarised and four vertically polarised antennas are achieved in total. Due to this feature, coupling between antenna pairs is reduced and the MIMO performances are enhanced. A prototype of the proposed antenna array was fabricated, and the experimental results show good impedance matching and acceptable isolation measured across the bands of interest. The MIMO performances such as envelope correlation coefficient, mean effective gain, multiplexing efficiency and channel capacity are also calculated. Besides, simulations of the antenna shifted to 3.5 GHz are also performed. The consistent performances indicate that the proposed structure has good scalability and is promising for future 5G smartphone applications.

Experimental evaluation of theperformance of 2×2 MIMO-OFDM for vehicle-to-infrastructure communications

In this paper, a novel 2×2 multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) testbed based on an Analog Devices AD9361 highly integrated radio frequency (RF) agile transceiver was specifically implemented for the purpose of estimating and analyzing MIMO-OFDM channel capacity in vehicle-to-infrastructure (V2I) environments using the 920 MHz industrial, scientific, and medical (ISM) band. We implemented two-dimensional discrete cosine transform-based filtering to reduce the channel estimation errors and show its effectiveness on our measurement results. We have also analyzed the effects of channel estimation error on the MIMO channel capacity by simulation. Three different scenarios of subcarrier spacing were investigated which correspond to IEEE 802.11p, Long-Term Evolution (LTE), and Digital Video Broadcasting Terrestrial (DVB-T)(2k) standards. An extensive MIMO-OFDM V2I channel measurement campaign was performed in a suburban environment. Analysis of the measured MIMO channel capacity results as a function of the transmitter-to-receiver (TX-RX) separation distance up to 250 m shows that the variance of the MIMO channel capacity is larger for the near-range line-of-sight (LOS) scenarios than for the long-range non-LOS cases, using a fixed receiver signal-to-noise ratio (SNR) criterion. We observed that the largest capacity values were achieved at LOS propagation despite the common assumption of a degenerated MIMO channel in LOS. We consider that this is due to the large angular spacing between MIMO subchannels which occurs when the receiver vehicle rooftop antennas pass by the fixed transmitter antennas at close range, causing MIMO subchannels to be orthogonal. In addition, analysis on the effects of different subcarrier spacings on MIMO-OFDM channel capacity showed negligible differences in mean channel capacity for the subcarrier spacing range investigated. Measured channels described in this paper are available on request.

PIFA-based 16 × 20 large MIMO cube antenna

A wideband dual polarized planar inverted F antenna-based 16 × 20 multi-input multi-output (MIMO) antenna cube with radome is designed and developed with an aim to achieve high data rate (>1 Gbps) wireless link in an urban street grid scenario. Developed antenna is mechanically stable and has a volume of 1.8λo3. All the elements have a wide impedance bandwidth from 2.4 to 2.8 GHz (VSWR < 1.6), low mutual coupling (<−15 dB) with almost hemispherical coverage (120° beam width) and peak gain of 3 dBi. MATLAB codes were generated to calculate mean effective gain (MEG), envelop correlation and channel capacity using simulated and measured values of antenna parameter. For urban street grid line of sight case, expected channel capacity of our 16 × 20 MIMO cube antenna is 80 b/s/Hz at 30-dB SNR, with MEG (0 dB) and envelop correlation coefficient less than 0.7. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:685–690, 2015

Accuracy of MIMO Channel Capacity Equation Based Only on &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$S$&lt;/tex&gt; &lt;/formula&gt;-Parameters of MIMO Antenna

Since the evaluation of multiple-input multiple-output (MIMO) antennas requires full information of its complex radiation patterns as well as propagation channels, its design procedures and analyses are cumbersome and complicated in general. In this letter, the accuracy of a closed-form capacity formula for mean MIMO channel capacity is investigated, where the S-parameter of the antenna is needed but the antenna must be lossless. Numerical analyses show that this formula gives mean channel capacity with a good accuracy when the signal-to-noise ratio is sufficiently high.

Statistical Characterization of the Indoor Low-Voltage Narrowband Power Line Communication Channel

This paper presents a novel statistical characterization of the indoor low-voltage (LV) narrowband power line communication (PLC) channel in CENELEC and FCC/ARIB bands. Experimental measurements of electrical network complex transfer functions were used to determine, for the frequency range up to 500 kHz, the statistics of the average channel gain, the delay spread parameters, the coherence bandwidth and the channel capacity. The average measured channel attenuation exhibits values between 16.36 and 26.95 dB with a mean of 20.75 dB in the frequency band from 10 to 500 kHz. The root mean square (rms) delay spread has a mean value of 2.12 μs with 90% of the channels revealing values below 3.20 μs. The minimum coherence bandwidth at 0.9 correlation level is of 1.23 kHz and the mean channel capacity is of 5.32 Mbps. The lognormal behavior is confirmed and justified for the rms delay spread but not for the average channel gain. The negative correlation between these two parameters is examined, and the relationships between the different studied metrics are also explored.

A scalable joint routing and scheduling scheme for large-scale wireless sensor networks

The multihop configuration of a large-scale wireless sensor network enables multiple simultaneous transmissions without interference within the network. Existing time division multiple access (TDMA) scheduling schemes exploit gain based on the assumption that the path is optimally determined by a routing protocol. In contrast, our scheme jointly considers routing and scheduling and introduces several new concepts. We model a large-scale wireless sensor network as a tiered graph relative to its distance from the sink, and introduce the notion of relay graph and relay factor to direct the next-hop candidates toward the sink fairly and efficiently. The sink develops a transmission and reception schedule for the sensor nodes based on the tiered graph search for a set of nodes that can simultaneously transmit and receive. The resulting schedule eventually allows data from each sensor node to be delivered to the sink. We analyze our scheduling algorithm both numerically and by simulation, and we discuss the impact of protocol parameters. Further, we prove that our scheme is scalable to the number of nodes, from the perspectives of mean channel capacity and maximum number of concurrent transmission nodes. Compared with the existing TDMA scheduling schemes, our scheme shows better performance in network throughput, path length, end-to-end delay, and fairness index.