Energy efficiency(EE)of downlink distributed antenna system(DAS)with multiple receive antennas is investigated over composite Rayleigh fading channel that takes the path loss and lognormal shadow fading into account.O...Energy efficiency(EE)of downlink distributed antenna system(DAS)with multiple receive antennas is investigated over composite Rayleigh fading channel that takes the path loss and lognormal shadow fading into account.Our aim is to maximize EE which is defined as the ratio of the transmission rate to the total consumed power under the constraints of the maximum transmit power of each remote antenna.According to the definition of EE,the optimized objective function is formulated with the help of Lagrangian method.By using the Karush-KuhnTucker(KKT)conditions and numerical calculation,considering both the static and dynamic circuit power consumptions,an adaptive energy efficient power allocation(PA)scheme is derived.This scheme is different from the conventional iterative PA schemes based on EE maximization since it can provide closed-form expression of PA coefficients.Moreover,it can obtain the EE performance close to the conventional iterative scheme and exhaustive search method while reducing the computation complexity greatly.Simulation results verify the effectiveness of the proposed scheme.展开更多
In the existing Electronic Health Records(EHRs),the medical information of patients is completely controlled by various medical institutions.As such,patients have no dominant power over their own EHRs.These personal d...In the existing Electronic Health Records(EHRs),the medical information of patients is completely controlled by various medical institutions.As such,patients have no dominant power over their own EHRs.These personal data are not only inconvenient to access and share,but are also prone to cause privacy disclosure.The blockchain technology provides a new development direction in the medical field.Blockchain-based EHRs are characterized by decentralization,openness and non-tampering of records,which enable patients to better manage their own EHRs.In order to better protect the privacy of patients,only designated receivers can access EHRs,and receivers can authenticate the sharer to ensure that the EHRs are real and effective.In this study,we propose an identity-based signcryption scheme with multiple authorities for multiple receivers,which can resist N-1 collusion attacks among N authorities.In addition,the identity information of receivers is anonymous,so the relationship between them and the sharer is not disclosed.Under the random oracle model,it was proved that our scheme was secure and met the unforgeability and confidentiality requirements of signcryption.Moreover,we evaluated the performance of the scheme and found that it had the moderate signcryption efficiency and excellent signcryption attributes.展开更多
In this article, multiple receiver effects in a non-line-of-sight (NLOS) ultraviolet (UV) communication system is studied. The idea of using multiple receivers for diversity reception is known as a practical, effe...In this article, multiple receiver effects in a non-line-of-sight (NLOS) ultraviolet (UV) communication system is studied. The idea of using multiple receivers for diversity reception is known as a practical, effective and widely applied technique in wireless communications. The current approach is to use multiple antennas at the receiver in order to improve the quality of the received signal. A method of modeling and simulation is proposed to depict the principle and feasibility of the multiple receiver adopted in UV communication. The study provides an insight to the channel characteristics and achievable capabilities of ultraviolet communication systems with multiple receivers. It provides guidelines for practical system design with discussions on trade off between the receiver gain and the additional cost.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61571225,61571224)the Fundamental Research Funds for the Central Universities+2 种基金the Research Founding of Graduate Innovation Center in NUAA (No.kfjj20160409)the Qing Lan Project of Jiangsu,Shenzhen Strategic Emerging Industry Development Funds(No.JSGG20150331160845693)the Six Talent Peaks Project in Jiangsu Province(No.DZXX-007)
文摘Energy efficiency(EE)of downlink distributed antenna system(DAS)with multiple receive antennas is investigated over composite Rayleigh fading channel that takes the path loss and lognormal shadow fading into account.Our aim is to maximize EE which is defined as the ratio of the transmission rate to the total consumed power under the constraints of the maximum transmit power of each remote antenna.According to the definition of EE,the optimized objective function is formulated with the help of Lagrangian method.By using the Karush-KuhnTucker(KKT)conditions and numerical calculation,considering both the static and dynamic circuit power consumptions,an adaptive energy efficient power allocation(PA)scheme is derived.This scheme is different from the conventional iterative PA schemes based on EE maximization since it can provide closed-form expression of PA coefficients.Moreover,it can obtain the EE performance close to the conventional iterative scheme and exhaustive search method while reducing the computation complexity greatly.Simulation results verify the effectiveness of the proposed scheme.
基金This work was supported by the National Key Research and Development Project of China(Grant No.2017YFB0802302)the Science and Technology Support Project of Sichuan Province(Grant Nos.2016FZ0112,2017GZ0314,and 2018GZ0204)+2 种基金the Academic and Technical Leaders Training Funding Support Projects of Sichuan Province(Grant No.2016120080102643)the Application Foundation Project of Sichuan Province(Grant No.2017JY0168)the Science and Technology Project of Chengdu(Grant Nos.2017-RK00-00103-ZF,and 2016-HM01-00217-SF).
文摘In the existing Electronic Health Records(EHRs),the medical information of patients is completely controlled by various medical institutions.As such,patients have no dominant power over their own EHRs.These personal data are not only inconvenient to access and share,but are also prone to cause privacy disclosure.The blockchain technology provides a new development direction in the medical field.Blockchain-based EHRs are characterized by decentralization,openness and non-tampering of records,which enable patients to better manage their own EHRs.In order to better protect the privacy of patients,only designated receivers can access EHRs,and receivers can authenticate the sharer to ensure that the EHRs are real and effective.In this study,we propose an identity-based signcryption scheme with multiple authorities for multiple receivers,which can resist N-1 collusion attacks among N authorities.In addition,the identity information of receivers is anonymous,so the relationship between them and the sharer is not disclosed.Under the random oracle model,it was proved that our scheme was secure and met the unforgeability and confidentiality requirements of signcryption.Moreover,we evaluated the performance of the scheme and found that it had the moderate signcryption efficiency and excellent signcryption attributes.
文摘In this article, multiple receiver effects in a non-line-of-sight (NLOS) ultraviolet (UV) communication system is studied. The idea of using multiple receivers for diversity reception is known as a practical, effective and widely applied technique in wireless communications. The current approach is to use multiple antennas at the receiver in order to improve the quality of the received signal. A method of modeling and simulation is proposed to depict the principle and feasibility of the multiple receiver adopted in UV communication. The study provides an insight to the channel characteristics and achievable capabilities of ultraviolet communication systems with multiple receivers. It provides guidelines for practical system design with discussions on trade off between the receiver gain and the additional cost.