This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency band.In order to analyze the feasibility of the higher frequency band appli...This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency band.In order to analyze the feasibility of the higher frequency band applications,the cumulative distribution of simulated user throughput in a cellular is investigated firstly.It shows that capacity improvement can be obtained using higher operating frequency band,especially in hotspot scenarios.Secondly,the architecture of the distributed antenna system(DAS) is introduced to overcome the disadvantages of weak coverage and rank deficient for the traditional multiple-input multiple-output(MIMO) systems using higher frequency bands in line-of-sight(LOS)environments.In addition,a software-defined-radio(SDR) based Gbps wireless transmission system with scalable hardware architecture is designed and implemented.Finally,a demo of outdoor DAS coverage for high data throughput application is given.Field trials show that 1 Gbps data rate and a large coverage in outdoor environments can be achieved over 6.05 GHz.It is proved that the Gbps DAS system at a higher frequency band can be a successful model for future wireless broadband coverage in hotspot scenarios.展开更多
On the basis of an introduction of the Wigner Higher-Order spectra(WHOS)and a general class of time-frequency higher-order moment spectra,the geophysical signal was analyzed using the higher order time-frequency distr...On the basis of an introduction of the Wigner Higher-Order spectra(WHOS)and a general class of time-frequency higher-order moment spectra,the geophysical signal was analyzed using the higher order time-frequency distributions(TFD).Simulation results obtained in this paper show that the higher-order TFD(Wigner Bispectrum,Wigner Trispectrum and Choi-Williams Trispectrum)have much better Time-Frequency Concentration than the second-order TFD,and the reduced interference higher-order TFD such as CWT can effectively reduce the cross-term in multicomponent signals and simultaneously obtain high time-frequency concentration.展开更多
The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models...The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic elements.Therefore,a large storage size of memory and long solution time are often needed in solving higher-frequency problems.In this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic BEM.The first one uses a plane wave expansion,which can be used to model scattering problems.The second one uses a special plane wave expansion,which can be used tomodel radiation problems.Five examples are investigated to showthe advantages of the enriched elements.Compared with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational time.This improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.展开更多
Wave dissipation characteristics in SWAN （Simulating Waves Nearshore） model are investigated through numerical experiments. It is found that neither the fully developed integral parameters of wind waves （significan...Wave dissipation characteristics in SWAN （Simulating Waves Nearshore） model are investigated through numerical experiments. It is found that neither the fully developed integral parameters of wind waves （significant wave height and peak frequency） nor the high frequency spectral tail can be well reproduced by the default wave dissipation source terms. A new spectral dissipation source term is proposed, which comprises saturation based dissipation above two times of peak frequency and improved whitecapping dissipation at lower frequency spectrum. The reciprocal wave age （u./ep） is involved into the whitecapping model to adjust dissipation rate at different wind speed. The Phillips higher frequency saturation parameter in the saturation-based dissipation is no longer taken as a constant, but varies with wave age. Numerical validations demonstrate that both the wind wave generation process and higher frequency spectrum of wind waves can be well simulated by the new wave dissipation term.展开更多
Data rates and volume for mobile communication are ever-increasing with the growing number of users and connected devices.With the deployment of 5G and 6G on the horizon,wireless communication is advancing to higher f...Data rates and volume for mobile communication are ever-increasing with the growing number of users and connected devices.With the deployment of 5G and 6G on the horizon,wireless communication is advancing to higher frequencies and larger bandwidths enabling higher speeds and throughput.Current micro-acoustic resonator technology,a key component in radiofrequency front-end filters,is struggling to keep pace with these developments.This work presents an acoustic resonator architecture enabling multi-frequency,low-loss,and wideband filtering for the 5G and future 6G bands located above 3 GHz.Thanks to the exceptional performance of these resonators,filters for the 5G n77 and n79 bands are demonstrated,exhibiting fractional bandwidths of 25%and 13%,respectively,with low insertion loss of around 1 dB.With its unique frequency scalability and wideband capabilities,the reported architecture offers a promising option for filtering and multiplexing in future mobile devices.展开更多
With the surge in fifth-generation(5G)wireless systems and escalating growth of data traffic,the push for higher carrier frequencies with wider bandwidths intensifies.This work reveals the outstanding capabilities of ...With the surge in fifth-generation(5G)wireless systems and escalating growth of data traffic,the push for higher carrier frequencies with wider bandwidths intensifies.This work reveals the outstanding capabilities of wafer-level longitudinal leaky surface acoustic wave(LLSAW)devices on the lithium niobate on insulator(LNOI)platform in scaling SAW technology beyond 4 GHz by mass-produced lithography.Leveraging SiC-based LNOI,the fabricated LLSAW resonators showcase remarkable quality factor(Q),scalable electromechanical factor k_(eff)^(2)from 14%to 28%,and record high figure-of-merit(FoM)of 166 to 222 at 5-6 GHz.Targeted for diverse bands,LLSAW filters with adaptable bandwidths have been realized on specific LN-on-SiC platforms.The filters covering the n79 full band with a minimum insertion loss(IL_(min))of 0.85 dB and the 5 GHz Wi-Fi full band with an IL_(min)of 1.62 dB,have been demonstrated for the first time.These findings position LLSAW on LN-on-SiC platform as a promising commercial-grade candidate for pushing the SAW paradigm towards high frequency and wideband filtering.展开更多
基金supported in part by the National Natural Science Foundation of China(No.61402044)863 plan program of China(No.2015AA01 A706)+2 种基金Science Foundation of Beijing Education Commission(No.KM201511232011)Science Fundation of Beijing Information Science & Technology University(No.5211524100)Beijing Nova Program(No.Z161100004916086)
文摘This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency band.In order to analyze the feasibility of the higher frequency band applications,the cumulative distribution of simulated user throughput in a cellular is investigated firstly.It shows that capacity improvement can be obtained using higher operating frequency band,especially in hotspot scenarios.Secondly,the architecture of the distributed antenna system(DAS) is introduced to overcome the disadvantages of weak coverage and rank deficient for the traditional multiple-input multiple-output(MIMO) systems using higher frequency bands in line-of-sight(LOS)environments.In addition,a software-defined-radio(SDR) based Gbps wireless transmission system with scalable hardware architecture is designed and implemented.Finally,a demo of outdoor DAS coverage for high data throughput application is given.Field trials show that 1 Gbps data rate and a large coverage in outdoor environments can be achieved over 6.05 GHz.It is proved that the Gbps DAS system at a higher frequency band can be a successful model for future wireless broadband coverage in hotspot scenarios.
基金Supported by the National Natural Science Foundation of China(49904010)
文摘On the basis of an introduction of the Wigner Higher-Order spectra(WHOS)and a general class of time-frequency higher-order moment spectra,the geophysical signal was analyzed using the higher order time-frequency distributions(TFD).Simulation results obtained in this paper show that the higher-order TFD(Wigner Bispectrum,Wigner Trispectrum and Choi-Williams Trispectrum)have much better Time-Frequency Concentration than the second-order TFD,and the reduced interference higher-order TFD such as CWT can effectively reduce the cross-term in multicomponent signals and simultaneously obtain high time-frequency concentration.
基金the National Natural Science Foundation of China(https://www.nsfc.gov.cn/,Project No.11972179)the Natural Science Foundation of Guangdong Province(http://gdstc.gd.gov.cn/,No.2020A1515010685)the Department of Education of Guangdong Province(http://edu.gd.gov.cn/,No.2020ZDZX2008).
文摘The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic elements.Therefore,a large storage size of memory and long solution time are often needed in solving higher-frequency problems.In this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic BEM.The first one uses a plane wave expansion,which can be used to model scattering problems.The second one uses a special plane wave expansion,which can be used tomodel radiation problems.Five examples are investigated to showthe advantages of the enriched elements.Compared with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational time.This improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.
基金The Public Science and Technology Research Funds Projects of Ocean,State Oceanic Administration of the People’s Republic of China,under contract No.201005033
文摘Wave dissipation characteristics in SWAN （Simulating Waves Nearshore） model are investigated through numerical experiments. It is found that neither the fully developed integral parameters of wind waves （significant wave height and peak frequency） nor the high frequency spectral tail can be well reproduced by the default wave dissipation source terms. A new spectral dissipation source term is proposed, which comprises saturation based dissipation above two times of peak frequency and improved whitecapping dissipation at lower frequency spectrum. The reciprocal wave age （u./ep） is involved into the whitecapping model to adjust dissipation rate at different wind speed. The Phillips higher frequency saturation parameter in the saturation-based dissipation is no longer taken as a constant, but varies with wave age. Numerical validations demonstrate that both the wind wave generation process and higher frequency spectrum of wind waves can be well simulated by the new wave dissipation term.
基金support from the Swiss National Science Foundation(SNSF)under projects CRSII5_189967 and 200020_184935.S.S。
文摘Data rates and volume for mobile communication are ever-increasing with the growing number of users and connected devices.With the deployment of 5G and 6G on the horizon,wireless communication is advancing to higher frequencies and larger bandwidths enabling higher speeds and throughput.Current micro-acoustic resonator technology,a key component in radiofrequency front-end filters,is struggling to keep pace with these developments.This work presents an acoustic resonator architecture enabling multi-frequency,low-loss,and wideband filtering for the 5G and future 6G bands located above 3 GHz.Thanks to the exceptional performance of these resonators,filters for the 5G n77 and n79 bands are demonstrated,exhibiting fractional bandwidths of 25%and 13%,respectively,with low insertion loss of around 1 dB.With its unique frequency scalability and wideband capabilities,the reported architecture offers a promising option for filtering and multiplexing in future mobile devices.
基金supported in part by the National Key Research and Development Program of China(Grant No.2022YFB3606700)Natural Science Foundation of Beijing Municipality(Grant No.JQ20010)National Natural Science Foundation of China(Grant No.52002205)。
文摘With the surge in fifth-generation(5G)wireless systems and escalating growth of data traffic,the push for higher carrier frequencies with wider bandwidths intensifies.This work reveals the outstanding capabilities of wafer-level longitudinal leaky surface acoustic wave(LLSAW)devices on the lithium niobate on insulator(LNOI)platform in scaling SAW technology beyond 4 GHz by mass-produced lithography.Leveraging SiC-based LNOI,the fabricated LLSAW resonators showcase remarkable quality factor(Q),scalable electromechanical factor k_(eff)^(2)from 14%to 28%,and record high figure-of-merit(FoM)of 166 to 222 at 5-6 GHz.Targeted for diverse bands,LLSAW filters with adaptable bandwidths have been realized on specific LN-on-SiC platforms.The filters covering the n79 full band with a minimum insertion loss(IL_(min))of 0.85 dB and the 5 GHz Wi-Fi full band with an IL_(min)of 1.62 dB,have been demonstrated for the first time.These findings position LLSAW on LN-on-SiC platform as a promising commercial-grade candidate for pushing the SAW paradigm towards high frequency and wideband filtering.
