This paper develops a general and tractable framework for the finite-sized downlink terahertz(THz)network.Specifically,the molecular absorption loss,receiver locations,directional antennas,and dynamic blockage are tak...This paper develops a general and tractable framework for the finite-sized downlink terahertz(THz)network.Specifically,the molecular absorption loss,receiver locations,directional antennas,and dynamic blockage are taken into account.Using the tools from stochastic geometry,the exact expressions of the blind probability,signal-to-interference-plus-noise ratio(SINR)coverage probability,and area spectral efficiency(ASE)for the reference receivers and random receivers are derived.The upper bounds of the SINR coverage probability are also obtained by using the generalized dominant interferers approach.Numerical results validate the accuracy of our theoretical analysis and suggest that two or more dominant interferers are required to provide sufficiently tight approximations for the SINR coverage probability.We also show that densifying the finite terahertz networks over a certain density threshold will degrade the coverage probability while the ASE keeps increasing.Moreover,deploying more obstructions appropriately in ultra-dense THz networks will benefit both the coverage probability and ASE.展开更多
As an emerging vertical heterogeneous network architecture that integrates the satellite-based space networks,air networks,and traditional ground networks,space–air–ground integrated network(SAGIN)is developed to re...As an emerging vertical heterogeneous network architecture that integrates the satellite-based space networks,air networks,and traditional ground networks,space–air–ground integrated network(SAGIN)is developed to realize the Internet of everything,global coverage,and ubiquitous intelligent communications.However,SAGIN also faces quite a few challenges due to its unique characteristics,such as highly complex network architecture,highly dynamic node topology,time-varying communication channels,and restricted resources.In this paper,we first introduce the architecture and benefits of SAGIN,and then present the faced challenges.Next,we discuss some key technologies in SAGIN.In particular,we discuss the flexible access in the realization of a dynamic communication architecture,explore some efficient resource scheduling methods to avoid wastage of resources,and investigate the secure communications,such as covert communications,physical layer security,and anti-jamming communications,in SAGIN.Finally,the potential future directions are discussed.展开更多
Quantum remote sensing utilizes quantum entanglement between the probe and the receiver to enhance the capability to sense a remote target.Quantum illumination is considered as a promising protocol to realize such a q...Quantum remote sensing utilizes quantum entanglement between the probe and the receiver to enhance the capability to sense a remote target.Quantum illumination is considered as a promising protocol to realize such a quantum technology in an environment of high loss and intense noise.However,the protocol requires an additional on-demand quantum memory,the imperfect performance of which diminishes the quantum advantage and limits the enhancement of sensing.In this paper,we propose a new protocol for quantum remote sensing based on quantum illumination with atom-light entangled interface.Compared to conventional light-only quantum illumination,the proposed protocol utilizes Raman coupling to create a long-lived atomic spin wave entangled with a Stokes light.The atomic spin wave,automatically built-in memory via the Raman coupling,acts as a local reference.The entangled Stokes light is used as a probe to irradiate a remote target.Meanwhile,the returned probe light from target is detected through coupling again to the atomic spin wave.A joint measurement on the returned probe light and spin wave is performed to discriminate the target.A 4 dB quantum enhancement over classical illumination is estimated.The atom-light entangled interface naturally integrates the quantum source,quantum memory,and quantum receiver in a single unit which exhibits great potential to develop highly compact and portable devices for quantum-enhanced remote sensing.展开更多
基金National Natural Science Foundation of China(No.61771054).
文摘This paper develops a general and tractable framework for the finite-sized downlink terahertz(THz)network.Specifically,the molecular absorption loss,receiver locations,directional antennas,and dynamic blockage are taken into account.Using the tools from stochastic geometry,the exact expressions of the blind probability,signal-to-interference-plus-noise ratio(SINR)coverage probability,and area spectral efficiency(ASE)for the reference receivers and random receivers are derived.The upper bounds of the SINR coverage probability are also obtained by using the generalized dominant interferers approach.Numerical results validate the accuracy of our theoretical analysis and suggest that two or more dominant interferers are required to provide sufficiently tight approximations for the SINR coverage probability.We also show that densifying the finite terahertz networks over a certain density threshold will degrade the coverage probability while the ASE keeps increasing.Moreover,deploying more obstructions appropriately in ultra-dense THz networks will benefit both the coverage probability and ASE.
基金supported by the National Natural Science Foundation of China under grants U23B2005,62201054,62201055,62371047Beijing Natural Science Foundation under grant JQ23015Beijing Nova Program under grant Z211100002121161.
文摘As an emerging vertical heterogeneous network architecture that integrates the satellite-based space networks,air networks,and traditional ground networks,space–air–ground integrated network(SAGIN)is developed to realize the Internet of everything,global coverage,and ubiquitous intelligent communications.However,SAGIN also faces quite a few challenges due to its unique characteristics,such as highly complex network architecture,highly dynamic node topology,time-varying communication channels,and restricted resources.In this paper,we first introduce the architecture and benefits of SAGIN,and then present the faced challenges.Next,we discuss some key technologies in SAGIN.In particular,we discuss the flexible access in the realization of a dynamic communication architecture,explore some efficient resource scheduling methods to avoid wastage of resources,and investigate the secure communications,such as covert communications,physical layer security,and anti-jamming communications,in SAGIN.Finally,the potential future directions are discussed.
基金support from the Innovation Program for Quantum Science and Technology 2021ZD0303200the National Science Foundation of China(Grant NO.12234014,11904227,12204304,11654005)+4 种基金Shanghai Municipal Science and Technology Major Project(Grant NO.2019SHZDZX01)the Sailing Program of Shanghai Science and Technology Committee under Grant 19YF1421800the Fundamental Research Funds for the Central Universities,and the Fellowship of China Postdoctoral Science Foundation(Grant No.2020TQ0193,2021M702146,2021M702150,2021M702147,2022T150413)the National Key Research and Development Program of China under Grant number 2016YFA0302001support from the Shanghai talent program.
文摘Quantum remote sensing utilizes quantum entanglement between the probe and the receiver to enhance the capability to sense a remote target.Quantum illumination is considered as a promising protocol to realize such a quantum technology in an environment of high loss and intense noise.However,the protocol requires an additional on-demand quantum memory,the imperfect performance of which diminishes the quantum advantage and limits the enhancement of sensing.In this paper,we propose a new protocol for quantum remote sensing based on quantum illumination with atom-light entangled interface.Compared to conventional light-only quantum illumination,the proposed protocol utilizes Raman coupling to create a long-lived atomic spin wave entangled with a Stokes light.The atomic spin wave,automatically built-in memory via the Raman coupling,acts as a local reference.The entangled Stokes light is used as a probe to irradiate a remote target.Meanwhile,the returned probe light from target is detected through coupling again to the atomic spin wave.A joint measurement on the returned probe light and spin wave is performed to discriminate the target.A 4 dB quantum enhancement over classical illumination is estimated.The atom-light entangled interface naturally integrates the quantum source,quantum memory,and quantum receiver in a single unit which exhibits great potential to develop highly compact and portable devices for quantum-enhanced remote sensing.
