In this paper, we propose a simplified spatial channel sounding method by utilizing bistatic synthetic aperture radar(BiSAR) principles. Despite the different deployment geometries compared with a conventional BiSAR s...In this paper, we propose a simplified spatial channel sounding method by utilizing bistatic synthetic aperture radar(BiSAR) principles. Despite the different deployment geometries compared with a conventional BiSAR system, the feasibility of the approach is established by 1) the proposed method achieves a better spatial resolution than conventional directional channel sounders and 2) reconstruction algorithms based on time-domain backprojection in conjunction with a digital elevation model provide a good imaging performance and are suitable for reconstructing the spatial distribution of scatterers. Simulations of a high-speed rail(HSR) scenario demonstrate that the estimated power delay profiles(PDPs) and power angle profiles(PAPs) are close to the actual values.展开更多
Terahertz(THz)communications are envisioned as a key technology for the sixth-generation wireless communication system(6G).However,it is not practical to perform large-scale channel measurements with high degrees of f...Terahertz(THz)communications are envisioned as a key technology for the sixth-generation wireless communication system(6G).However,it is not practical to perform large-scale channel measurements with high degrees of freedom at THz frequency band.This makes empirical or stochastic modeling approaches relying on measurements no longer stand.In order to break through the bottleneck of scarce fulldimensional channel sounding measurements,this paper presents a novel paradigm for THz channel modeling towards 6G.With the core of high-performance ray tracing(RT),the presented paradigm requires merely quite limited channel sounding to calibrate the geometry and material electromagnetic(EM)properties of the three-dimensional(3D)environment model in the target scenarios.Then,through extensive RT simulations,the parameters extracted from RT simulations can be fed into either ray-based novel stochastic channel models or cluster-based standard channel model families.Verified by RT simulations,these models can generate realistic channels that are valuable for the design and evaluation of THz systems.Representing two ends of 6G THz use cases from microscopy to macroscopy,case studies are made for close-proximity communications,wireless connections on a desktop,and smart rail mobility,respectively.Last but not least,new concerns on channel modeling resulting from distinguishing features of THz wave are discussed regarding propagation,antenna array,and device aspects,respectively.展开更多
Due to the large amount of unused and unexplored spectrum resources, the so-called subTerahertz(sub-THz) frequency bands from 100 to 300 GHz are seen as promising bands for the next generation of wireless communicatio...Due to the large amount of unused and unexplored spectrum resources, the so-called subTerahertz(sub-THz) frequency bands from 100 to 300 GHz are seen as promising bands for the next generation of wireless communication systems. Channel modeling at sub-THz bands is essential for the design and deployment of future wireless communication systems. Channel measurement is a widely adopted method to obtain channel characteristics and establish mathematical channel models. Channel measurements depend on the design and construction of channel sounders. Thus, reliable channel sounding techniques and accurate channel measurements are required. In this paper, the requirements of an ideal channel sounder are discussed and the main channel sounding techniques are described for the subTHz frequency bands. The state-of-the-art sub-THz channel sounders reported in the literature and respective channel measurements are presented. Moreover, a vector network analyzer(VNA) based channel sounder, which supports frequency bands from 220 to330 GHz is presented and its performance capability and limitation are evaluated. This paper also discussed the challenge and future outlook of the sub-THz channel sounders and measurements.展开更多
With the increasing demand for high bandwidth wireless communication systems,and with a congested spectrum in the sub-6 GHz frequency bands,researchers have been looking into exploration of millimeter wave(mmWave)and ...With the increasing demand for high bandwidth wireless communication systems,and with a congested spectrum in the sub-6 GHz frequency bands,researchers have been looking into exploration of millimeter wave(mmWave)and sub-terahertz(subTHz)frequency bands.Channel modeling is essential for system design and performance evaluation of new wireless communication systems.Accurate channel modeling relies on reliable measured channel data,which is collected by high-fidelity channel sounders.Furthermore,it is of importance to understand to which extent channel parameters are frequency dependent in typical deployment scenario(including both indoor short-range and outdoor long-range scenarios).To achieve this purpose,this paper presents a stateof-art long-range 28 GHz and 300 GHz VNA-based channel sounder using optical cable solutions,which can support a measurement range up to 300 m and 600 m in principle,respectively.The design,development and validation of the long-range channel sounders at mmWave and sub-THz bands are reported,with a focus on their system principle,link budget,and backto-back measurements.Furthermore,a measurement campaign in an indoor corridor is performed using the developed 300 GHz system and 28 GHz channel sounding systems.Both measured channels at the 28 GHz and 300 GHz channels are shown to be highly sparse and specular.A higher number of Multi Path Components(MPC)are observed for the 28 GHz system,while the same main MPC are observed for both systems.展开更多
When an inaudible sound covert channel(ISCC)attack is launched inside a computer system,sensitive data are converted to inaudible sound waves and then transmitted.The receiver at the other end picks up the sound signa...When an inaudible sound covert channel(ISCC)attack is launched inside a computer system,sensitive data are converted to inaudible sound waves and then transmitted.The receiver at the other end picks up the sound signal,from which the original sensitive data can be recovered.As a forceful countermeasure against the ISCC attack,strong noise can be used to jam the channel and literally shut down any possible sound data transmission.In this paper,enhanced ISCC is proposed,whose transmission frequency can be dynamically changed.Essentially,if the transmitter detects that the covert channel is being jammed,the transmitter and receiver both will switch to another available frequency and re-establish their communications,following the proposed communications protocol.Experimental results show that the proposed enhanced ISCC can remain connected even in the presence of a strong jamming noise source.Correspondingly,a detection method based on frequency scanning is proposed to help to combat such an anti-jamming sound channel.With the proposed countermeasure,the bit error rate(BER)of the data communications over enhanced ISCC soars to more than 48%,essentially shutting down the data transmission,and thus neutralizing the security threat.展开更多
A new 6.1 channel surround sound system and its two signal mixing methods are proposed. Theoretical and experimental results show that the system is able to recreate 360° sound image in horizontal plane. Especial...A new 6.1 channel surround sound system and its two signal mixing methods are proposed. Theoretical and experimental results show that the system is able to recreate 360° sound image in horizontal plane. Especiallys compared with current 5.1 channel system, lateral and rear image of the new system is improved obviously. Therefore it is suitable to be used as a general surround sound system. It is also proved that, the new system is fully compatible with 5.1 channel system, and current methods are available to record 6.1 channel signals.展开更多
In this paper based on the study of time-space-variant characteristics of ocean sound Channel, the channel response function is found by adaptive filtering. The obtained channel′s response function is applied to matc...In this paper based on the study of time-space-variant characteristics of ocean sound Channel, the channel response function is found by adaptive filtering. The obtained channel′s response function is applied to match the channel and satisfactory effect is shown. In the case of time-invariant channel the key problem is how to increase the convergent speed of adaptive match algorithm. For this purpose, besides using an adaptive step size factor and performing adaptive filtering in the filtering in the frequency domain, a rational selection of the weight parameters (the number of weights and the time relationship between the weights) is proposed.The result shows that under the condition of rational selection of the weight parameters a complicated response function of the channel can be expressed by a limited number of weights.展开更多
The two-axis underwater channel often exists in deep ocean. Sound propagation in the two-axis underwater channel is a benchmark problem for computational methods of underwater acoustics. In this paper, the generalized...The two-axis underwater channel often exists in deep ocean. Sound propagation in the two-axis underwater channel is a benchmark problem for computational methods of underwater acoustics. In this paper, the generalized phase-integral (WKBZ) normal mo de approach is extended to deal with this kind of problem. Numerical results show that the extended WKBZ approach is effective.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.6147088the Natural Sciences and Engineering Research Council of Canada-Discovery Grant Program
文摘In this paper, we propose a simplified spatial channel sounding method by utilizing bistatic synthetic aperture radar(BiSAR) principles. Despite the different deployment geometries compared with a conventional BiSAR system, the feasibility of the approach is established by 1) the proposed method achieves a better spatial resolution than conventional directional channel sounders and 2) reconstruction algorithms based on time-domain backprojection in conjunction with a digital elevation model provide a good imaging performance and are suitable for reconstructing the spatial distribution of scatterers. Simulations of a high-speed rail(HSR) scenario demonstrate that the estimated power delay profiles(PDPs) and power angle profiles(PAPs) are close to the actual values.
基金supported by the Fundamental Research Funds for the Central Universities 2020JBZD005NSFC under Grant(61771036,61901029,U1834210,and 61725101)+4 种基金the State Key Laboratory of Rail Traffic Control and Safety(Contract No.RCS2020ZZ005)Beijing Jiaotong Universitythe ZTE CorporationState Key Laboratory of Mobile Network and Mobile Multimedia TechnologyBeijing Natural Science Foundation under Grant L201023。
文摘Terahertz(THz)communications are envisioned as a key technology for the sixth-generation wireless communication system(6G).However,it is not practical to perform large-scale channel measurements with high degrees of freedom at THz frequency band.This makes empirical or stochastic modeling approaches relying on measurements no longer stand.In order to break through the bottleneck of scarce fulldimensional channel sounding measurements,this paper presents a novel paradigm for THz channel modeling towards 6G.With the core of high-performance ray tracing(RT),the presented paradigm requires merely quite limited channel sounding to calibrate the geometry and material electromagnetic(EM)properties of the three-dimensional(3D)environment model in the target scenarios.Then,through extensive RT simulations,the parameters extracted from RT simulations can be fed into either ray-based novel stochastic channel models or cluster-based standard channel model families.Verified by RT simulations,these models can generate realistic channels that are valuable for the design and evaluation of THz systems.Representing two ends of 6G THz use cases from microscopy to macroscopy,case studies are made for close-proximity communications,wireless connections on a desktop,and smart rail mobility,respectively.Last but not least,new concerns on channel modeling resulting from distinguishing features of THz wave are discussed regarding propagation,antenna array,and device aspects,respectively.
基金supported by the EURAMET European Partnership on Metrology(EPM),under the 21NRM03 Metrology for Emerging Wireless Standards(MEWS)projectThe project(21NRM03 MEWS)has received funding from the EPM,co-financed from the European Union’s Horizon Europe Research and Innovation Programme,and by the Participating States。
文摘Due to the large amount of unused and unexplored spectrum resources, the so-called subTerahertz(sub-THz) frequency bands from 100 to 300 GHz are seen as promising bands for the next generation of wireless communication systems. Channel modeling at sub-THz bands is essential for the design and deployment of future wireless communication systems. Channel measurement is a widely adopted method to obtain channel characteristics and establish mathematical channel models. Channel measurements depend on the design and construction of channel sounders. Thus, reliable channel sounding techniques and accurate channel measurements are required. In this paper, the requirements of an ideal channel sounder are discussed and the main channel sounding techniques are described for the subTHz frequency bands. The state-of-the-art sub-THz channel sounders reported in the literature and respective channel measurements are presented. Moreover, a vector network analyzer(VNA) based channel sounder, which supports frequency bands from 220 to330 GHz is presented and its performance capability and limitation are evaluated. This paper also discussed the challenge and future outlook of the sub-THz channel sounders and measurements.
基金supported by EURAMET European Partnership on Metrology Programme (MEWS) and under the framework of European COST INTERACT action(CA20120)
文摘With the increasing demand for high bandwidth wireless communication systems,and with a congested spectrum in the sub-6 GHz frequency bands,researchers have been looking into exploration of millimeter wave(mmWave)and sub-terahertz(subTHz)frequency bands.Channel modeling is essential for system design and performance evaluation of new wireless communication systems.Accurate channel modeling relies on reliable measured channel data,which is collected by high-fidelity channel sounders.Furthermore,it is of importance to understand to which extent channel parameters are frequency dependent in typical deployment scenario(including both indoor short-range and outdoor long-range scenarios).To achieve this purpose,this paper presents a stateof-art long-range 28 GHz and 300 GHz VNA-based channel sounder using optical cable solutions,which can support a measurement range up to 300 m and 600 m in principle,respectively.The design,development and validation of the long-range channel sounders at mmWave and sub-THz bands are reported,with a focus on their system principle,link budget,and backto-back measurements.Furthermore,a measurement campaign in an indoor corridor is performed using the developed 300 GHz system and 28 GHz channel sounding systems.Both measured channels at the 28 GHz and 300 GHz channels are shown to be highly sparse and specular.A higher number of Multi Path Components(MPC)are observed for the 28 GHz system,while the same main MPC are observed for both systems.
基金This work was supported partly by the National Natural Science Foundation of China under Grant No.61971200partly by Zhejiang Lab under Grants No.2021LE0AB01 and No.2021PC0AC01+3 种基金partly by the Major Scientific Research Project of Zhejiang Lab under Grant No.2021LE0AC01partly by the Key Technologies R&D Program of Jiangsu(Prospective and Key Technologies for Industry)under Grant No.BE2021003partly by the National Key Research and Development Program of China under Grant No.2019QY0705by the Guangdong Provincial Key Laboratory of Short-Range Wireless Detection and Communication under Grants No.2014B030301010 and No.2017B030314003.
文摘When an inaudible sound covert channel(ISCC)attack is launched inside a computer system,sensitive data are converted to inaudible sound waves and then transmitted.The receiver at the other end picks up the sound signal,from which the original sensitive data can be recovered.As a forceful countermeasure against the ISCC attack,strong noise can be used to jam the channel and literally shut down any possible sound data transmission.In this paper,enhanced ISCC is proposed,whose transmission frequency can be dynamically changed.Essentially,if the transmitter detects that the covert channel is being jammed,the transmitter and receiver both will switch to another available frequency and re-establish their communications,following the proposed communications protocol.Experimental results show that the proposed enhanced ISCC can remain connected even in the presence of a strong jamming noise source.Correspondingly,a detection method based on frequency scanning is proposed to help to combat such an anti-jamming sound channel.With the proposed countermeasure,the bit error rate(BER)of the data communications over enhanced ISCC soars to more than 48%,essentially shutting down the data transmission,and thus neutralizing the security threat.
基金National Natural Science Foundation of China !(project 19974012) The Science and Technology Project 98-J-010 - 01 of Guang
文摘A new 6.1 channel surround sound system and its two signal mixing methods are proposed. Theoretical and experimental results show that the system is able to recreate 360° sound image in horizontal plane. Especiallys compared with current 5.1 channel system, lateral and rear image of the new system is improved obviously. Therefore it is suitable to be used as a general surround sound system. It is also proved that, the new system is fully compatible with 5.1 channel system, and current methods are available to record 6.1 channel signals.
文摘In this paper based on the study of time-space-variant characteristics of ocean sound Channel, the channel response function is found by adaptive filtering. The obtained channel′s response function is applied to match the channel and satisfactory effect is shown. In the case of time-invariant channel the key problem is how to increase the convergent speed of adaptive match algorithm. For this purpose, besides using an adaptive step size factor and performing adaptive filtering in the filtering in the frequency domain, a rational selection of the weight parameters (the number of weights and the time relationship between the weights) is proposed.The result shows that under the condition of rational selection of the weight parameters a complicated response function of the channel can be expressed by a limited number of weights.
文摘The two-axis underwater channel often exists in deep ocean. Sound propagation in the two-axis underwater channel is a benchmark problem for computational methods of underwater acoustics. In this paper, the generalized phase-integral (WKBZ) normal mo de approach is extended to deal with this kind of problem. Numerical results show that the extended WKBZ approach is effective.
