Degree of freedom(DOF)is a key indicator for spatial multiplexing layers of a wireless channel.Traditionally,the channel of a multiple-input multiple-output(MIMO)half-wavelength dipole array has a DOF that equals the ...Degree of freedom(DOF)is a key indicator for spatial multiplexing layers of a wireless channel.Traditionally,the channel of a multiple-input multiple-output(MIMO)half-wavelength dipole array has a DOF that equals the antenna number.However,recent studies suggest that the DOF could be less than the antenna number when strong mutual coupling is considered.We utilize a mutual-coupling-compliant channel model to investigate the DOF of the holographic MIMO(HMIMO)channel and give a upper bound of the DOF with strong mutual coupling.Our numerical simulations demonstrate that a dense array can support more DOF per unit aperture as compared with a half-wavelength MIMO system.展开更多
China-EU Summit charts the course for the development of China-EU relations with its first onsite session since 2019.D ESPITE the din about de-risking and decoupling made by some Western media,the convening of the 24t...China-EU Summit charts the course for the development of China-EU relations with its first onsite session since 2019.D ESPITE the din about de-risking and decoupling made by some Western media,the convening of the 24th EU-China Summit in Beijing on December 7,the first in-person one since 2019,showed the significant importance the two sides attached to the bilateral relations,and their mutual intention to steer the important ties toward more fruitful cooperation.展开更多
A4-port multiple-input multiple-output(MIMO)antenna exhibiting lowmutual coupling andUWBperformance is developed.The octagonal-shaped four-antenna elements are connected with a 50microstrip feed line that is arranged...A4-port multiple-input multiple-output(MIMO)antenna exhibiting lowmutual coupling andUWBperformance is developed.The octagonal-shaped four-antenna elements are connected with a 50microstrip feed line that is arranged rotationally to achieve the orthogonal polarization for improving the MIMO system performance.The antenna has a wideband impedance bandwidth of 7.5GHz with S11<−10 dB from(103.44%)3.5–11GHz and inter-element isolation higher than 20 dB.Antenna validation is carried out by verifying the simulated and measured results after fabricating the antenna.The results in the form of omnidirectional radiation patterns,peak gain(≥4 dBi),and Envelope Correlation Coefficient(ECC)(≤0.01)are extracted to validate the suggested antenna performance.Aswell,time-domain analysis was investigated to demonstrate the operation of the suggested antenna in wideband applications.Finally,the simulated and experimental outcomes have almost similar tendenciesmaking the antenna suitable for its use in UWBMIMOapplications.展开更多
To overcome the mutual coupling (MC) of multiple antennas in millimeter wave (mmWave) communication systems, a novel beam design method with low complexity is proposed in this paper. Firstly, an equivalent channel mod...To overcome the mutual coupling (MC) of multiple antennas in millimeter wave (mmWave) communication systems, a novel beam design method with low complexity is proposed in this paper. Firstly, an equivalent channel model incorporating the effect of MC is analyzed and established, and then an optimal precoding / combiner vector for beamforming is derived. On this basis, by using greedy geometric (GG) algorithm, a novel hybrid beam design method is proposed. Finally, the performance of proposed method is analyzed and compared with other traditional ones. The simulation results show that the proposed method has better suppression of the MC effect as well as lower complexity.展开更多
A decoupling-estimation signal parameters via rotarional invariance technique(ESPRIT) method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output(MIMO)...A decoupling-estimation signal parameters via rotarional invariance technique(ESPRIT) method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output(MIMO) radar.Two steps are carried out in this method.The decoupling operation between angle and mutual coupling estimates is realized by choosing the auxiliary elements on both sides of the transmit and receive uniform linear arrays(ULAs).Then the ESPRIT method is resilient against the unknown mutual coupling matrix(MCM) and can be directly utilized to estimate the direction of departure(DOD) and the direction of arrival(DOA).Moreover,the mutual coupling coefficient is estimated by finding the solution of the linear constrained optimization problem.The proposed method allows an efficient DOD and DOA estimates with automatic pairing.Simulation results are presented to verify the effectiveness of the proposed method.展开更多
Anovel compact E shape High Impedance Surface(HIS) Electromagnetic Band-Gap(EBG) comprising Amended Minkowski Fractal Boundary(AMFB),Added Metal Strips(AMS),and metal plated via printed on a Rogers TMM 10i substrate i...Anovel compact E shape High Impedance Surface(HIS) Electromagnetic Band-Gap(EBG) comprising Amended Minkowski Fractal Boundary(AMFB),Added Metal Strips(AMS),and metal plated via printed on a Rogers TMM 10i substrate is presented.The first order AMFB and ABS are introduced for equivalent capacitance enhancement and miniaturization with effective space-filling characteristics.The dimension of lattice size is only The proposed structure exhibits a most compact characteristic about 35% size reduction as compared with conven-tional mushroom-like HIS-EBG,and better surface-wave decoupling of around 9 dB at the operating frequency band.Details of design parameters which affect the whole performance of certain band-gap are intensively investigated.A constructed prototype is potential candidate for antenna system per-formance enhancement.展开更多
A new and exact calculation method for the mutual impedance matrix of receiving arrays is proposed. The mutual impedance matrix is derived from electromagnetic boundary conditions and can be used to relate the couplin...A new and exact calculation method for the mutual impedance matrix of receiving arrays is proposed. The mutual impedance matrix is derived from electromagnetic boundary conditions and can be used to relate the coupling free open-circuit voltages, instead of the conventional ones, to the measured voltages. A remarkable improvement on compensation for the coupling effects is shown in the direction finding applications, while a simple relationship between measured terminal voltages and the coupling free voltages is remained.展开更多
A novel Direction-Of-Arrival (DOA) estimation method is proposed in the presence of mutual coupling using the joint sparse recovery. In the proposed method, the eigenvector corresponding to the maximum eigenvalue of c...A novel Direction-Of-Arrival (DOA) estimation method is proposed in the presence of mutual coupling using the joint sparse recovery. In the proposed method, the eigenvector corresponding to the maximum eigenvalue of covariance matrix of array measurement is viewed as the signal to be represented. By exploiting the geometrical property in steering vectors and the symmetric Toeplitz structure of Mutual Coupling Matrix (MCM), the redundant dictionaries containing the DOA information are constructed. Consequently, the optimization model based on joint sparse recovery is built and then is solved through Second Order Cone Program (SOCP) and Interior Point Method (IPM). The DOA estimates are gotten according to the positions of nonzeros elements. At last, computer simulations demonstrate the excellent performance of the proposed method.展开更多
We propose a method for estimating the mutual coupling coefficient among antennas in this paper which is based on the principle of signal subspace and the simulated annealing (SA) algorithm. The computer simulation ...We propose a method for estimating the mutual coupling coefficient among antennas in this paper which is based on the principle of signal subspace and the simulated annealing (SA) algorithm. The computer simulation has been conducted to illustrate the' excellent performance of this method and to demonstrate that it is statistically efficient. The benefit of this new method is that calibration signals and unknown signals can be received simultaneously, during the course of calibration.展开更多
A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output(MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5...A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output(MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5.8 GHz,and 7.1 GHz with an improved impedance bandwidth of 37% and a reduced mutual coupling of-33 dB.These results are better compared to a normal E shaped patch antenna designed with same size and thickness,achieved without using any additional decoupling methods.A 2×2 MIMO system employing the Swastika shaped patch antennas is analyzed using computational electromagnetic ray tracing software for an indoor environment.The results show an improvement in the capacity compared to a 2×2 MIMO system developed with dipole antennas.The proposed antenna is a good choice for MIMO systems operating for several Ultra WideBand(UWB) applications.展开更多
In this paper, the capacity of a multiuser Multiple Input Multiple Output (MIMO) system employing the block diagonalization broadcasting scheme in presence of spatial correlation and mutual coupling is investigated. I...In this paper, the capacity of a multiuser Multiple Input Multiple Output (MIMO) system employing the block diagonalization broadcasting scheme in presence of spatial correlation and mutual coupling is investigated. It is shown by computer simulations that, in general, the presence of spatial correlation decreases the capacity of a multiuser MIMO system. However, for some particular antenna element spacing mutual coupling decreases the spatial correlation rendering an increased capacity. The optimized diagonalization broadcasting technique with a two-stage power allocation scheme is proposed and verified. The presented simulations results confirm the advantage of the proposed broadcasting scheme.展开更多
A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate an...A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate and complete analysis of the mutual coupling effect on multiple antenna systems.展开更多
Based on the integral equation formulations and the moment method, a novel closed form solution for analyzing the mutual coupling effect between the cylindrical comformal rectangular microstrip patch antennas is pres...Based on the integral equation formulations and the moment method, a novel closed form solution for analyzing the mutual coupling effect between the cylindrical comformal rectangular microstrip patch antennas is presented. By using this algorithm, the elements of the impedance matrix and exciting vector are cast into closed forms, thus the computational efficiency is improved dramatically. Numerical results are presented to verify the validity and reliability of the algorithm.展开更多
A compact CPW-fed double T-Shaped antenna is proposed for dual-band wireless local area network (WLAN) operations. For the proposed antenna, the -10 dB return loss bandwidth could reach about 25.5% for the 2.4 GHz ban...A compact CPW-fed double T-Shaped antenna is proposed for dual-band wireless local area network (WLAN) operations. For the proposed antenna, the -10 dB return loss bandwidth could reach about 25.5% for the 2.4 GHz band and 5.7 % for the 5 GHz band, which meet the required bandwidth specification of WLAN standard. To reduce the mutual coupling and get high isolation between two dual-band antennas, we proposed the novel electromagnetic band gap (EBG) structures. When the EBG structure is employed, a -13dB and -30dB mutual coupling reduction is achieved at 2.4 and 5.2 GHz. It shows that the features of small size, uniplanar structure, good radiation characteristics and small mutual coupling are promising for multi-input multi-output (MIMO) applications.展开更多
This work provides the design and analysis of a single layer,linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization.Detailed analysis was carried out at 26GHz design frequency using ...This work provides the design and analysis of a single layer,linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization.Detailed analysis was carried out at 26GHz design frequency using the simulations of the reflectarray unit cells as well as the periodic reflectarray antenna.The simulated results were verified by the scattering parameter and far-fieldmeasurements of the unit cell and periodic arrays,respectively.Aclose agreement between the simulated and measured results was observed in all the cases.Apart from the unit cells and reflectarray,the waveguide and horn antenna were also fabricated to be used in the measurements.The measured scattering parameter results of the proposed circular ring unit cells provided a maximum reflection loss of 2.8 dB with phase errors below 10°.On the other hand,the measured far-field results of the 20×20 reflectarray antenna provided a maximum gain of 26.45 dB with a maximum 3 dB beam width of 12°and 1 dB gain drop bandwidth of 13.1%.The performance demonstrated by the proposed reflectarray antenna makes it a potential candidate to be used in modern-day applications such as 5th Generation(5G)and 6th Generation(6G)communication systems.展开更多
This paper reports on investigations into capacity of ad hoc network whose nodes are equipped with multiple element antennas (MEAs). The investigation of this multi-user Multiple Input Multiple Output (MIMO) system ta...This paper reports on investigations into capacity of ad hoc network whose nodes are equipped with multiple element antennas (MEAs). The investigation of this multi-user Multiple Input Multiple Output (MIMO) system takes into account mutual coupling (MC) in addition to spatial correlation that is present in array antennas. A closed-form expression for an upper bound of mutual information (capacity) of MIMO ad hoc network is derived. An optimal signal transmission scheme is proposed to maximize the MIMO ad hoc network capacity. Simulation results for capacity of non-optimized and optimized cases of signal transmission are presented.展开更多
The number of wireless electronic gadgets used in mobile communication, vehicle collision avoidance system, compact radars, etc. is extremely increasing at a rapid rate. Thus, the characteristics of the antennas invol...The number of wireless electronic gadgets used in mobile communication, vehicle collision avoidance system, compact radars, etc. is extremely increasing at a rapid rate. Thus, the characteristics of the antennas involved in these gadgets are to be designed very stringently so as to avoid interferences & coupling and to improve compatibility, susceptibility, etc. Compact smart antenna with improved performance is highly essential to meet this challenging scenario. Mutual coupling between various elements of an array is one of the main factors which can be considered for improvement of performance of the antenna. Influence of mutual coupling on performance of the antenna is considered in this paper and various techniques to minimize this effect are presented. Effect of mutual coupling on radiation characteristics of the antenna can be compensated employing various methods like Conventional Mutual Impedance (CMI), Receiving Mutual Impedance (RMI). Analysis is presented as comparison between the two methods for different number of elements in the array. Analysis is also presented for different geometries of the array like circular and elliptical for improved performance. The results show performance improvement in the proposed array for parameters like SNR and Speed of convergence.展开更多
Coupled oscillators are common in many scientific areas,such as optics,communications,engi-neering,biology,etc.The synchronization of oscillators has important practical applications.This letter focuses on synchroniza...Coupled oscillators are common in many scientific areas,such as optics,communications,engi-neering,biology,etc.The synchronization of oscillators has important practical applications.This letter focuses on synchronization of coupled hyperchaotic oscillators,which exists in natureand in laboratory and is very important.展开更多
An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal ...An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.展开更多
基金supported in part by National Key Research and Develop⁃ment Program of China under Grant No.2020YFB1807600.
文摘Degree of freedom(DOF)is a key indicator for spatial multiplexing layers of a wireless channel.Traditionally,the channel of a multiple-input multiple-output(MIMO)half-wavelength dipole array has a DOF that equals the antenna number.However,recent studies suggest that the DOF could be less than the antenna number when strong mutual coupling is considered.We utilize a mutual-coupling-compliant channel model to investigate the DOF of the holographic MIMO(HMIMO)channel and give a upper bound of the DOF with strong mutual coupling.Our numerical simulations demonstrate that a dense array can support more DOF per unit aperture as compared with a half-wavelength MIMO system.
文摘China-EU Summit charts the course for the development of China-EU relations with its first onsite session since 2019.D ESPITE the din about de-risking and decoupling made by some Western media,the convening of the 24th EU-China Summit in Beijing on December 7,the first in-person one since 2019,showed the significant importance the two sides attached to the bilateral relations,and their mutual intention to steer the important ties toward more fruitful cooperation.
文摘A4-port multiple-input multiple-output(MIMO)antenna exhibiting lowmutual coupling andUWBperformance is developed.The octagonal-shaped four-antenna elements are connected with a 50microstrip feed line that is arranged rotationally to achieve the orthogonal polarization for improving the MIMO system performance.The antenna has a wideband impedance bandwidth of 7.5GHz with S11<−10 dB from(103.44%)3.5–11GHz and inter-element isolation higher than 20 dB.Antenna validation is carried out by verifying the simulated and measured results after fabricating the antenna.The results in the form of omnidirectional radiation patterns,peak gain(≥4 dBi),and Envelope Correlation Coefficient(ECC)(≤0.01)are extracted to validate the suggested antenna performance.Aswell,time-domain analysis was investigated to demonstrate the operation of the suggested antenna in wideband applications.Finally,the simulated and experimental outcomes have almost similar tendenciesmaking the antenna suitable for its use in UWBMIMOapplications.
基金supported by Aeronautical Science Foundation of China (2017ZC52021)the Major Program of National Natural Science Foundation of China (61827801)
文摘To overcome the mutual coupling (MC) of multiple antennas in millimeter wave (mmWave) communication systems, a novel beam design method with low complexity is proposed in this paper. Firstly, an equivalent channel model incorporating the effect of MC is analyzed and established, and then an optimal precoding / combiner vector for beamforming is derived. On this basis, by using greedy geometric (GG) algorithm, a novel hybrid beam design method is proposed. Finally, the performance of proposed method is analyzed and compared with other traditional ones. The simulation results show that the proposed method has better suppression of the MC effect as well as lower complexity.
基金supported by the National Natural Science Foundation of China (60702015)
文摘A decoupling-estimation signal parameters via rotarional invariance technique(ESPRIT) method is presented for multi-target localization with unknown mutual coupling in bistatic multiple-input multiple-output(MIMO) radar.Two steps are carried out in this method.The decoupling operation between angle and mutual coupling estimates is realized by choosing the auxiliary elements on both sides of the transmit and receive uniform linear arrays(ULAs).Then the ESPRIT method is resilient against the unknown mutual coupling matrix(MCM) and can be directly utilized to estimate the direction of departure(DOD) and the direction of arrival(DOA).Moreover,the mutual coupling coefficient is estimated by finding the solution of the linear constrained optimization problem.The proposed method allows an efficient DOD and DOA estimates with automatic pairing.Simulation results are presented to verify the effectiveness of the proposed method.
基金Supported by the 2010 Natural Science Foundation of Shanghai (No. 09ZR1430400)
文摘Anovel compact E shape High Impedance Surface(HIS) Electromagnetic Band-Gap(EBG) comprising Amended Minkowski Fractal Boundary(AMFB),Added Metal Strips(AMS),and metal plated via printed on a Rogers TMM 10i substrate is presented.The first order AMFB and ABS are introduced for equivalent capacitance enhancement and miniaturization with effective space-filling characteristics.The dimension of lattice size is only The proposed structure exhibits a most compact characteristic about 35% size reduction as compared with conven-tional mushroom-like HIS-EBG,and better surface-wave decoupling of around 9 dB at the operating frequency band.Details of design parameters which affect the whole performance of certain band-gap are intensively investigated.A constructed prototype is potential candidate for antenna system per-formance enhancement.
基金the National High Technology Research and Development Program of China (2002AA123032)
文摘A new and exact calculation method for the mutual impedance matrix of receiving arrays is proposed. The mutual impedance matrix is derived from electromagnetic boundary conditions and can be used to relate the coupling free open-circuit voltages, instead of the conventional ones, to the measured voltages. A remarkable improvement on compensation for the coupling effects is shown in the direction finding applications, while a simple relationship between measured terminal voltages and the coupling free voltages is remained.
基金Supported by the Innovation Foundation for Outstanding Postgraduates in the Electronic Engineering Institute of PLA (No. 2009YB005)
文摘A novel Direction-Of-Arrival (DOA) estimation method is proposed in the presence of mutual coupling using the joint sparse recovery. In the proposed method, the eigenvector corresponding to the maximum eigenvalue of covariance matrix of array measurement is viewed as the signal to be represented. By exploiting the geometrical property in steering vectors and the symmetric Toeplitz structure of Mutual Coupling Matrix (MCM), the redundant dictionaries containing the DOA information are constructed. Consequently, the optimization model based on joint sparse recovery is built and then is solved through Second Order Cone Program (SOCP) and Interior Point Method (IPM). The DOA estimates are gotten according to the positions of nonzeros elements. At last, computer simulations demonstrate the excellent performance of the proposed method.
基金Supported by the 863 High Technology Project ofChina (2001AA631050)
文摘We propose a method for estimating the mutual coupling coefficient among antennas in this paper which is based on the principle of signal subspace and the simulated annealing (SA) algorithm. The computer simulation has been conducted to illustrate the' excellent performance of this method and to demonstrate that it is statistically efficient. The benefit of this new method is that calibration signals and unknown signals can be received simultaneously, during the course of calibration.
文摘A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output(MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5.8 GHz,and 7.1 GHz with an improved impedance bandwidth of 37% and a reduced mutual coupling of-33 dB.These results are better compared to a normal E shaped patch antenna designed with same size and thickness,achieved without using any additional decoupling methods.A 2×2 MIMO system employing the Swastika shaped patch antennas is analyzed using computational electromagnetic ray tracing software for an indoor environment.The results show an improvement in the capacity compared to a 2×2 MIMO system developed with dipole antennas.The proposed antenna is a good choice for MIMO systems operating for several Ultra WideBand(UWB) applications.
文摘In this paper, the capacity of a multiuser Multiple Input Multiple Output (MIMO) system employing the block diagonalization broadcasting scheme in presence of spatial correlation and mutual coupling is investigated. It is shown by computer simulations that, in general, the presence of spatial correlation decreases the capacity of a multiuser MIMO system. However, for some particular antenna element spacing mutual coupling decreases the spatial correlation rendering an increased capacity. The optimized diagonalization broadcasting technique with a two-stage power allocation scheme is proposed and verified. The presented simulations results confirm the advantage of the proposed broadcasting scheme.
基金Supported by National High Technology Research and Development Program of China (No. 2002AA123032)
文摘A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate and complete analysis of the mutual coupling effect on multiple antenna systems.
文摘Based on the integral equation formulations and the moment method, a novel closed form solution for analyzing the mutual coupling effect between the cylindrical comformal rectangular microstrip patch antennas is presented. By using this algorithm, the elements of the impedance matrix and exciting vector are cast into closed forms, thus the computational efficiency is improved dramatically. Numerical results are presented to verify the validity and reliability of the algorithm.
文摘A compact CPW-fed double T-Shaped antenna is proposed for dual-band wireless local area network (WLAN) operations. For the proposed antenna, the -10 dB return loss bandwidth could reach about 25.5% for the 2.4 GHz band and 5.7 % for the 5 GHz band, which meet the required bandwidth specification of WLAN standard. To reduce the mutual coupling and get high isolation between two dual-band antennas, we proposed the novel electromagnetic band gap (EBG) structures. When the EBG structure is employed, a -13dB and -30dB mutual coupling reduction is achieved at 2.4 and 5.2 GHz. It shows that the features of small size, uniplanar structure, good radiation characteristics and small mutual coupling are promising for multi-input multi-output (MIMO) applications.
基金The authors extend their appreciation to the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University for funding this work through Research Group No.RG-21-12-08.
文摘This work provides the design and analysis of a single layer,linearly polarized millimeter wave reflectarray antenna with mutual coupling optimization.Detailed analysis was carried out at 26GHz design frequency using the simulations of the reflectarray unit cells as well as the periodic reflectarray antenna.The simulated results were verified by the scattering parameter and far-fieldmeasurements of the unit cell and periodic arrays,respectively.Aclose agreement between the simulated and measured results was observed in all the cases.Apart from the unit cells and reflectarray,the waveguide and horn antenna were also fabricated to be used in the measurements.The measured scattering parameter results of the proposed circular ring unit cells provided a maximum reflection loss of 2.8 dB with phase errors below 10°.On the other hand,the measured far-field results of the 20×20 reflectarray antenna provided a maximum gain of 26.45 dB with a maximum 3 dB beam width of 12°and 1 dB gain drop bandwidth of 13.1%.The performance demonstrated by the proposed reflectarray antenna makes it a potential candidate to be used in modern-day applications such as 5th Generation(5G)and 6th Generation(6G)communication systems.
文摘This paper reports on investigations into capacity of ad hoc network whose nodes are equipped with multiple element antennas (MEAs). The investigation of this multi-user Multiple Input Multiple Output (MIMO) system takes into account mutual coupling (MC) in addition to spatial correlation that is present in array antennas. A closed-form expression for an upper bound of mutual information (capacity) of MIMO ad hoc network is derived. An optimal signal transmission scheme is proposed to maximize the MIMO ad hoc network capacity. Simulation results for capacity of non-optimized and optimized cases of signal transmission are presented.
文摘The number of wireless electronic gadgets used in mobile communication, vehicle collision avoidance system, compact radars, etc. is extremely increasing at a rapid rate. Thus, the characteristics of the antennas involved in these gadgets are to be designed very stringently so as to avoid interferences & coupling and to improve compatibility, susceptibility, etc. Compact smart antenna with improved performance is highly essential to meet this challenging scenario. Mutual coupling between various elements of an array is one of the main factors which can be considered for improvement of performance of the antenna. Influence of mutual coupling on performance of the antenna is considered in this paper and various techniques to minimize this effect are presented. Effect of mutual coupling on radiation characteristics of the antenna can be compensated employing various methods like Conventional Mutual Impedance (CMI), Receiving Mutual Impedance (RMI). Analysis is presented as comparison between the two methods for different number of elements in the array. Analysis is also presented for different geometries of the array like circular and elliptical for improved performance. The results show performance improvement in the proposed array for parameters like SNR and Speed of convergence.
基金The project supported by Nuclear Science Foundation of China and the National Project of Science and Technology for REturned Students.
文摘Coupled oscillators are common in many scientific areas,such as optics,communications,engi-neering,biology,etc.The synchronization of oscillators has important practical applications.This letter focuses on synchronization of coupled hyperchaotic oscillators,which exists in natureand in laboratory and is very important.
文摘An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.