Mobile edge computing(MEC) is a novel technique that can reduce mobiles' computational burden by tasks offloading, which emerges as a promising paradigm to provide computing capabilities in close proximity to mobi...Mobile edge computing(MEC) is a novel technique that can reduce mobiles' computational burden by tasks offloading, which emerges as a promising paradigm to provide computing capabilities in close proximity to mobile users. In this paper, we will study the scenario where multiple mobiles upload tasks to a MEC server in a sing cell, and allocating the limited server resources and wireless channels between mobiles becomes a challenge. We formulate the optimization problem for the energy saved on mobiles with the tasks being dividable, and utilize a greedy choice to solve the problem. A Select Maximum Saved Energy First(SMSEF) algorithm is proposed to realize the solving process. We examined the saved energy at different number of nodes and channels, and the results show that the proposed scheme can effectively help mobiles to save energy in the MEC system.展开更多
In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, ...In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, we propose a joint hybrid precoding algorithm for single-user mmWave MIMO systems in this paper. By using the concept of equivalent channel, the proposed algorithm skillfully utilizes the idea of alternating optimization to complete the design of RF precoder and combiner. Then, the baseband precoder and combiner are computed by calculating the singular value decomposition of the equivalent channel. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance with quite low complexity. Moreover, we investigate the effects of quantization on the analog components and find that the proposed scheme is effective even with coarse quantization.展开更多
We investigate computationally the attenuation and reffection of Terahertz (THz) wave using targets coated with plasmas. The simulators are the Wentzel-Kramer-Brillouin (WKB) method and finite-difierence time-domain (...We investigate computationally the attenuation and reffection of Terahertz (THz) wave using targets coated with plasmas. The simulators are the Wentzel-Kramer-Brillouin (WKB) method and finite-difierence time-domain (FDTD) method. The relation between the frequency of the incident electromagnetic (EM) wave and the attenuation caused by unmagnitized plasma is analyzed. The results demonstrate that the amount of absorbed power is a decreasing function of the EM wave frequency and the plasma collision frequency. For THz band incident wave, the attenuation that is caused by plasma is small when the plasma has common density and the collision frequency. This conclusion has fine applying foreground for plasma anti stealth.展开更多
This paper explores the multi-frequency independent channel interference alignment(MFC-IA) system of 3 channels and4 users,and single data stream transmit,i.e.(3×3,1)~4 system.We derive the analytic solution for(...This paper explores the multi-frequency independent channel interference alignment(MFC-IA) system of 3 channels and4 users,and single data stream transmit,i.e.(3×3,1)~4 system.We derive the analytic solution for(3×3,1)~4 MFC-IA system.Based on the analytic solution,an optimization problem is proposed aim at the optimal IA solution.Then based on such a math model,we propose a simulated annealing(SA) algorithm to search optimal IA solution.The simulation results show that the simulated annealing IA algorithm has a better sum rate performance than iterative maximize signal to interference plus noise ratio(Max-SINR) algorithm.This result can be extended to single data stream multi-antenna IA system with 3 antennas and4 users.展开更多
Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output system...Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.展开更多
A zero-IF transmitter for Cognitive Radio(CR) application is presented.To effectively reduce the interference between Power Amplifier(PA) and Voltage Controlled Oscillator(VCO),two VCOs are adopted,one is 450 MHz and ...A zero-IF transmitter for Cognitive Radio(CR) application is presented.To effectively reduce the interference between Power Amplifier(PA) and Voltage Controlled Oscillator(VCO),two VCOs are adopted,one is 450 MHz and the other is from 1148 MHz to 1252 MHz with an 8 MHz step,so the frequency of them are different from the operational frequency of PA.The Local Oscillator(LO) of the modulator generated by mixing the signals of the two VCOs has a low phase noise of-82 dBc/Hz with an offset of 1 kHz.The measurement result of the transmitter shows that the Adjacent Channel Power Ratio(ACPR) is less than-47.5 dBc at 27 dBm output,and the Error Vector Magnitude(EVM) is less than 1.7%.展开更多
An electrically scanned lens antenna for two dimensional scanning is presented. The antenna system is composed of a (N × 1) feed array, a binary diffractive dielectric lens (BDL) and a voltage-controlled ferroele...An electrically scanned lens antenna for two dimensional scanning is presented. The antenna system is composed of a (N × 1) feed array, a binary diffractive dielectric lens (BDL) and a voltage-controlled ferroelectric lens (VCFL). The feeds at different offset foci of the BDL generate receiving beams pointing to different angles to perform beam scanning in one dimension;the VCFL made of ferroelectric slabs which show linear permittivity gradient when loaded with corresponding DC voltages generate linear phase shift to steer the beam in the other dimension.展开更多
Based on local Taylor expansions on the complex plane,a method for fast locating all modes(FLAM) of spectral-domain Green's Functions in a planar layered medium is developed in this paper. SDP-FLAM,a combination o...Based on local Taylor expansions on the complex plane,a method for fast locating all modes(FLAM) of spectral-domain Green's Functions in a planar layered medium is developed in this paper. SDP-FLAM,a combination of FLAM with the steepest descent path algorithm(SDP) ,is employed to accurately evaluate the spatial-domain Green's functions in a layered medium. According to the theory of complex analysis,the relationship among the poles,branch points and Riemann sheets is also analyzed rigorously. To inverse the Green's functions from spectral to spatial domain,SDP-FLAM method and discrete complex image method(DCIM) are applied to the non-near field region and the near filed region,respectively. The significant advantage of SDP-FLAM lies in its capability of calculating Green's functions in a layered medium of moderate thickness with loss or without loss. Some numerical examples are presented to validate SDP-FLAM method.展开更多
Two types of dual periodic circuits are introduced. The distributions of passbands and stopbands are generated from their dispersion relationships. Based on the study, Brillouin diagrams of three representative specia...Two types of dual periodic circuits are introduced. The distributions of passbands and stopbands are generated from their dispersion relationships. Based on the study, Brillouin diagrams of three representative special cases are drawn; S parameters of these three cases are simulated by Aglient ADS; the S parameters of one of the three cases are verified by an experiment. The phase characteristics are compared with those generated from the dispersion relationship. The theoretical analysis and the experimental verification show that both types of the periodic structures can behave as electromagnetic band gap (EBG) structures, right-handed structures (RHS), and left-handed structures (LHS), when they operate at different frequency ranges. Thus, the possibility of a physical structure showing these three different characteristics at different frequency ranges is proven.展开更多
A planar millimeter-wave shared-aperture array antenna is proposed and designed in this paper.By composing the substrate integrated waveguide(SIW)and the stripline,the K-band antenna is embedded inside the Ka-band ant...A planar millimeter-wave shared-aperture array antenna is proposed and designed in this paper.By composing the substrate integrated waveguide(SIW)and the stripline,the K-band antenna is embedded inside the Ka-band antenna to achieve a smaller size and a low profile by sharing an aperture.The Ka-band antenna radiates through the parallel slot pairs on the surface of the SIW cavities with horizontal polar‐ization,while the K-band antenna radiates through the butterfly-shaped slots with vertical polarization,which are also designed on the surface.Then the two array antennas can radiate by sharing a common ap‐erture with high isolation.To verify this idea,a proto‐type of an 8×8 shared-aperture array antenna has been designed with center frequencies of 19 and 30 GHz and fabricated using multilayer printed circuit board(PCB)technology.展开更多
The Fabry-Perot resonator (FPR) antenna has found wide applications in microwave and millimeter waves and recently attracted considerable interest. In this paper, a summary of planar and cylindrical structures, analyt...The Fabry-Perot resonator (FPR) antenna has found wide applications in microwave and millimeter waves and recently attracted considerable interest. In this paper, a summary of planar and cylindrical structures, analytic models and research development is presented, and a comparison between these structures and analytic models is made, showing that such analytic models as the FP cavity mode, electromagnetic band gap (EBG) defect mode, transmission line mode, and leaky-wave mode are consistent when applied to analyze this type of resonator antenna. Some interesting topics under recent research, including dual or multi-band, improvement of gain bandwidth, low profile and beam control, are surveyed.展开更多
基金supported by NSFC(No. 61571055)fund of SKL of MMW (No. K201815)Important National Science & Technology Specific Projects(2017ZX03001028)
文摘Mobile edge computing(MEC) is a novel technique that can reduce mobiles' computational burden by tasks offloading, which emerges as a promising paradigm to provide computing capabilities in close proximity to mobile users. In this paper, we will study the scenario where multiple mobiles upload tasks to a MEC server in a sing cell, and allocating the limited server resources and wireless channels between mobiles becomes a challenge. We formulate the optimization problem for the energy saved on mobiles with the tasks being dividable, and utilize a greedy choice to solve the problem. A Select Maximum Saved Energy First(SMSEF) algorithm is proposed to realize the solving process. We examined the saved energy at different number of nodes and channels, and the results show that the proposed scheme can effectively help mobiles to save energy in the MEC system.
基金supported by NSFC (No. 61571055)fund of SKL of MMW (No. K201815) Important National Science & Technology Specific Projects (2017ZX03001028)
文摘In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, we propose a joint hybrid precoding algorithm for single-user mmWave MIMO systems in this paper. By using the concept of equivalent channel, the proposed algorithm skillfully utilizes the idea of alternating optimization to complete the design of RF precoder and combiner. Then, the baseband precoder and combiner are computed by calculating the singular value decomposition of the equivalent channel. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance with quite low complexity. Moreover, we investigate the effects of quantization on the analog components and find that the proposed scheme is effective even with coarse quantization.
基金the National Natural Science Foundation of China (60771017)the China Postdoctoral ScienceFoundation (20060390272)
文摘We investigate computationally the attenuation and reffection of Terahertz (THz) wave using targets coated with plasmas. The simulators are the Wentzel-Kramer-Brillouin (WKB) method and finite-difierence time-domain (FDTD) method. The relation between the frequency of the incident electromagnetic (EM) wave and the attenuation caused by unmagnitized plasma is analyzed. The results demonstrate that the amount of absorbed power is a decreasing function of the EM wave frequency and the plasma collision frequency. For THz band incident wave, the attenuation that is caused by plasma is small when the plasma has common density and the collision frequency. This conclusion has fine applying foreground for plasma anti stealth.
基金supported by the 863 Program of China under Grant No.2015AA01A703the Fundamental Research Funds for the Central Universities under Grant No.2014ZD03-02+1 种基金the National Natural Science Foundation of China(NSFC,No.61171104,61571055)fund of State Key Laboratory of Millimeter Wave(SKL of MMW,No.K201501)
文摘This paper explores the multi-frequency independent channel interference alignment(MFC-IA) system of 3 channels and4 users,and single data stream transmit,i.e.(3×3,1)~4 system.We derive the analytic solution for(3×3,1)~4 MFC-IA system.Based on the analytic solution,an optimization problem is proposed aim at the optimal IA solution.Then based on such a math model,we propose a simulated annealing(SA) algorithm to search optimal IA solution.The simulation results show that the simulated annealing IA algorithm has a better sum rate performance than iterative maximize signal to interference plus noise ratio(Max-SINR) algorithm.This result can be extended to single data stream multi-antenna IA system with 3 antennas and4 users.
基金supported by NSFC (No. 61571055)fund of SKL of MMW (No. K201815)Important National Science & Technology Specific Projects (2017ZX03001028)
文摘Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.
基金Supported by the National High-Tech Project (No. 2009AA011801)National Natural Science Foundation of China (No. 60621002)
文摘A zero-IF transmitter for Cognitive Radio(CR) application is presented.To effectively reduce the interference between Power Amplifier(PA) and Voltage Controlled Oscillator(VCO),two VCOs are adopted,one is 450 MHz and the other is from 1148 MHz to 1252 MHz with an 8 MHz step,so the frequency of them are different from the operational frequency of PA.The Local Oscillator(LO) of the modulator generated by mixing the signals of the two VCOs has a low phase noise of-82 dBc/Hz with an offset of 1 kHz.The measurement result of the transmitter shows that the Adjacent Channel Power Ratio(ACPR) is less than-47.5 dBc at 27 dBm output,and the Error Vector Magnitude(EVM) is less than 1.7%.
文摘An electrically scanned lens antenna for two dimensional scanning is presented. The antenna system is composed of a (N × 1) feed array, a binary diffractive dielectric lens (BDL) and a voltage-controlled ferroelectric lens (VCFL). The feeds at different offset foci of the BDL generate receiving beams pointing to different angles to perform beam scanning in one dimension;the VCFL made of ferroelectric slabs which show linear permittivity gradient when loaded with corresponding DC voltages generate linear phase shift to steer the beam in the other dimension.
基金This project was supported by the Na- tional Natural Science Foundation of China （Grant No. 6157110 and No. 61601120）, the Prospective Future Network Project of the Jiangsu Province, China （Grant No. BY2013095-1-18）, and the In- dependent Project of State Key Laboratory of Millimeter Waves （Grant No. Z201504）.
基金This project was supported by the National Natural Science Foundation of China （Grant No. 61571105）, the Prospective Future Network Project of the Jiangsu Province, China （Grant No. BY2013095-1-18）, and the Independent Project of State Key Laboratory of Millimeter Waves （Grant No. Z201504）.
基金Supported by the National Natural Science Foundation of China (Grant No. 60621002)the State Key Development Program for Basic Research of China (Grant No. 2009CB320200)
文摘Based on local Taylor expansions on the complex plane,a method for fast locating all modes(FLAM) of spectral-domain Green's Functions in a planar layered medium is developed in this paper. SDP-FLAM,a combination of FLAM with the steepest descent path algorithm(SDP) ,is employed to accurately evaluate the spatial-domain Green's functions in a layered medium. According to the theory of complex analysis,the relationship among the poles,branch points and Riemann sheets is also analyzed rigorously. To inverse the Green's functions from spectral to spatial domain,SDP-FLAM method and discrete complex image method(DCIM) are applied to the non-near field region and the near filed region,respectively. The significant advantage of SDP-FLAM lies in its capability of calculating Green's functions in a layered medium of moderate thickness with loss or without loss. Some numerical examples are presented to validate SDP-FLAM method.
基金Supported by the National Natural Science Foundation of China (Grant No. 60471018)
文摘Two types of dual periodic circuits are introduced. The distributions of passbands and stopbands are generated from their dispersion relationships. Based on the study, Brillouin diagrams of three representative special cases are drawn; S parameters of these three cases are simulated by Aglient ADS; the S parameters of one of the three cases are verified by an experiment. The phase characteristics are compared with those generated from the dispersion relationship. The theoretical analysis and the experimental verification show that both types of the periodic structures can behave as electromagnetic band gap (EBG) structures, right-handed structures (RHS), and left-handed structures (LHS), when they operate at different frequency ranges. Thus, the possibility of a physical structure showing these three different characteristics at different frequency ranges is proven.
基金the National Natural Science Foundation of China(No.62131008)the Fundamental Research Funds for the Central Universities,China(No.2242022k30003)。
文摘A planar millimeter-wave shared-aperture array antenna is proposed and designed in this paper.By composing the substrate integrated waveguide(SIW)and the stripline,the K-band antenna is embedded inside the Ka-band antenna to achieve a smaller size and a low profile by sharing an aperture.The Ka-band antenna radiates through the parallel slot pairs on the surface of the SIW cavities with horizontal polar‐ization,while the K-band antenna radiates through the butterfly-shaped slots with vertical polarization,which are also designed on the surface.Then the two array antennas can radiate by sharing a common ap‐erture with high isolation.To verify this idea,a proto‐type of an 8×8 shared-aperture array antenna has been designed with center frequencies of 19 and 30 GHz and fabricated using multilayer printed circuit board(PCB)technology.
基金Proje ct supported by the National Natural Science Foundation of China(No.61571055)the Fund of SKL of MMW(No.K201815)the Important National Science&Technology Specific Projects(No.20 17ZX03001028)
基金Project (Nos. 60671016 and 60621002) supported by the National Natural Science Foundation of China
文摘The Fabry-Perot resonator (FPR) antenna has found wide applications in microwave and millimeter waves and recently attracted considerable interest. In this paper, a summary of planar and cylindrical structures, analytic models and research development is presented, and a comparison between these structures and analytic models is made, showing that such analytic models as the FP cavity mode, electromagnetic band gap (EBG) defect mode, transmission line mode, and leaky-wave mode are consistent when applied to analyze this type of resonator antenna. Some interesting topics under recent research, including dual or multi-band, improvement of gain bandwidth, low profile and beam control, are surveyed.
