In cellular systems,establishing the initial symbol timing of potential preambles is the first step of a cell search.The envelope fluctuation of the downlink signal hinders the successful timing of conventional symbol...In cellular systems,establishing the initial symbol timing of potential preambles is the first step of a cell search.The envelope fluctuation of the downlink signal hinders the successful timing of conventional symbol timing methods.To solve this problem,a hybrid timing strategy is proposed with two novel detectors,namely the normalized replica-based detector and normalized differential detector.The strategy first detects all potential preambles via the normalized replica-based detector and then employs the normalized differential detector to verify the target preamble,which comes from the target cell and has the highest power.The strategy is unaffected by envelope fluctuation and has computational complexity comparable to that of conventional methods.Simu-lations and real-data tests show that the hybrid timing strategy is robust and practical for initial symbol timing.展开更多
Recently, the multi-hop cellular networks have been widely studied in order to enhance the cell performances such as the cell capacity. While most of these works merely use the multi-hop methods instead of direct tran...Recently, the multi-hop cellular networks have been widely studied in order to enhance the cell performances such as the cell capacity. While most of these works merely use the multi-hop methods instead of direct transmission without considering the co-channel inter-cell interference, signal transmission mode and the effects of the number of antennas. With the consideration of above important elements, this paper proposed an improved cellular system with multi-relay amplifies-andforward (AF) cooperative transmission scheme and the corresponding capacity expression is derived under the corresponding environment. By using the potential space diversity and selecting relays based on maximizing the capacity, the cellular system capacity can be improved effectively. The simulation results show that with the assistance of optimal selected relays, the improved cooperative cellular system capacity with multi-relay AF transmission scheme performs better than single-hop cellular system.展开更多
Within a cell of cellular system,cooperative relay technique can improve the performance of multicast efficiently,but it can cause the stream frequent interruptions because of the mobility of relay terminals.A video l...Within a cell of cellular system,cooperative relay technique can improve the performance of multicast efficiently,but it can cause the stream frequent interruptions because of the mobility of relay terminals.A video layered cooperative relay strategy is proposed to guarantee the continuity of multicast stream and retain high-bandwidth of the cooperative relay channel.Based on the capacity analysis for layered relay channel in the strategy,the optimal power allocation is studied to maximize capacity.After analyzing and optimizing the capacity in abstract models,the study is extended to a non-fading and a Gaussian wireless channel model to satisfy the scenario of cellular system.Giving the relay nodes position or distribution of noise power,the obtained results can determine the optimal power allocation among the transmitter and relay nodes.At last,the simulation results show that the strategy and its optimal power allocation have a significant improvement on the performance.展开更多
In this paper, an asynchronous cooperative cellular system applied with space-time block coding (STBC) is investigated. A signal detector is proposed based on parallel interference cancellation (PIC), to cancel the in...In this paper, an asynchronous cooperative cellular system applied with space-time block coding (STBC) is investigated. A signal detector is proposed based on parallel interference cancellation (PIC), to cancel the inter-symbol interference (ISI) caused by the imperfect synchronization. Simulation results show that the proposed PIC detector can effiectively suppress the ISI, but there is still a comparatively high error floor, due to the co-channel interference (CCI) of the cellular system.展开更多
It is known that dynamic channel assignment(D CA ) strategy outperforms the fixed channel assignment(FCA) strategy in omni-direc tional antenna cellular systems. One of the most important methods used in DCA w as chan...It is known that dynamic channel assignment(D CA ) strategy outperforms the fixed channel assignment(FCA) strategy in omni-direc tional antenna cellular systems. One of the most important methods used in DCA w as channel borrowing. But with the emergence of cell sectorization and spatial d ivision multiple access(SDMA) which are used to increase the capacity of cel lular systems, the channel assignment faces a series of new problems. In this pa per, a dynamic channel allocation scheme based on sectored cellular systems is p roposed. By introducing intra-cell channel borrowing (borrowing channels from n eighboring sectors) and inter-cell channel borrowing (borrowing channels from n eighboring cells) methods, previous DCA strategies, including compact pattern ba sed channel borrowing(CPCB) and greedy based dynamic channel assignment(GDCA) schemes proposed by the author, are improved significantly. The computer simu lation shows that either intra-cell borrowing scheme or inter-cell borrowing s cheme is efficient enough to uniform and non-uniform traffic service distributi ons.展开更多
The rapid developing of the fourth generation(4G)wireless communications has aroused tremendous demands for high speed data transmission due to the dissemination of various types of the intelligent user terminals as w...The rapid developing of the fourth generation(4G)wireless communications has aroused tremendous demands for high speed data transmission due to the dissemination of various types of the intelligent user terminals as well as the wireless multi-media services.It is predicted that the network throughput will increase展开更多
Multi-criteria handoff algorithms have been playing a more important role than the traditional handoff algorithms.In order to balance the satisfaction of users and the efficiency of networks,it is necessary to develop...Multi-criteria handoff algorithms have been playing a more important role than the traditional handoff algorithms.In order to balance the satisfaction of users and the efficiency of networks,it is necessary to develop new technologies to improve the validity of handoff algorithms.Intelligent and optimized handoff algorithms in hybrid networks that integrate Ad hoc and mobile cellular systems are well-adaptive and robust.They are able to implement handoffs adaptively,according to specific multi-factors such as different Quality of Service(QoS)requirements,network states and mobile node conditions in the future hybrid networks.Therefore,these intelligent and optimized algorithms can make more effective handover decision,and accordingly improve the system’s performance.The future research will tackle intelligent or optimized vertical handoff algorithms for integrated Ad hoc and mobile cellular networks to improve their whole system performance.展开更多
This paper focuses on the problem of secure transmission in a cellular system. A full-duplex base station using artificial noise is adopted to improve both the uplink and downlink secrecy rate via pairing terminals wh...This paper focuses on the problem of secure transmission in a cellular system. A full-duplex base station using artificial noise is adopted to improve both the uplink and downlink secrecy rate via pairing terminals which reverses the downlink and uplink of each other. We give the designs of artificial noise and the user's desired signal, and derive the pairing prin-ciple between terminals. Moreover, the influence of self-interference cancellation on secrecy rate is ex-plored. Simulation results show that the secrecy rate can get much better performance by adopting full-duplex artificial noise scheme and proposed pair-ing method. The downlink secrecy rate decreases with the distance between terminals. Besides the uplink secrecy rate is sensitive to the ability of self-interference cancellation.展开更多
This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighbori...This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighboring cells. It is shown that when using inter-cell relay, the number of calls in the congestion cell can be significantly increased. The congestion cell is divided into two parts. One is called non-relay area(NRA), in which a call directly communicates with the base station(BS) of a congested cell. The other is called relay area(RA), in which a call communicates with the BS of a neighboring cell through a relay station(RS). The two parts have different user-call densities. By adjusting the densities of two parts, we will maximize the number of supported calls inside a congested cell. The results show the benefits gained from inter-cell relay in congestion relief, which can reduce cell congestion by fully utilizing the available resources in the neighboring cells.展开更多
Power control is an important technique in WCDMA mobile systems for both increasing system capacity and guaranteeing the required QoS (time delay and wireless link transmission quality) of multimedia services. The opt...Power control is an important technique in WCDMA mobile systems for both increasing system capacity and guaranteeing the required QoS (time delay and wireless link transmission quality) of multimedia services. The optimum power control for narrow band CDMA cellular systems is a problem of single threshold optimization. Because these systems have only one type of traffic and have the same QoS requirement. However, WCDMA mobile system should provide multimedia services and different types of traffic have different QoS requirements. Thus, the power control in WCDMA mobile systems isn't a problem of single threshold optimizing, but turns into the optimizing problem of multi-threshold. We analyze the power control problem in WCDMA cellular mobile systems and propose the optimum transmitter power control algorithm. Three criteria to optimize transmitter power levels of multi-thresholds based on grading the priority orders of multimedia services are proposed. Simulation results show that the proposed algorithms are more effective than conventional algorithms and can provide better performance for WCDMA cellular mobile systems.展开更多
This paper presented a scheme of relayed cellular mobile telecommunication network,which only employs fixed digital relays and not more than two-hop relay routes.Power saving potential of the network is deeply studied...This paper presented a scheme of relayed cellular mobile telecommunication network,which only employs fixed digital relays and not more than two-hop relay routes.Power saving potential of the network is deeply studied under the assumption of not occupying additional frequency bands(i.e.relays share the same frequency bands as used by the base stations).Theoretical analysis and simulation results have both shown that,with the same radio coverage requirement,the necessary effective transmission powers in such a relayed network have greatly decreased compared to conventional cellular network.展开更多
This paper presents an efficient Radio Resource Management (RRM) strategy for adaptive Orthogo-nal Frequency Division Multiplexing (OFDM) cellular systems. In the proposed strategy, only those users who have the same ...This paper presents an efficient Radio Resource Management (RRM) strategy for adaptive Orthogo-nal Frequency Division Multiplexing (OFDM) cellular systems. In the proposed strategy, only those users who have the same distance from their base stations can reuse a same subcarrier. This can guarantee the received Carrier-to-Interference ratio (C/I) of each subcarrier to be acceptable as required by system planning. Then by employing different modulation scheme on each subcarrier according to its received C/I, system spectral effi-ciency can be gracefully increased. Analytical and simulation results show that the spectral efficiency is im-proved by 40% without sacrificing the Bit Error Rate (BER) performance and call blocking probability and sys-tem capacity of the proposed strategy is better than conventional systems.展开更多
Land use/land cover represents the interactive and comprehensive influences between human activities and natural conditions,leading to potential conflicts among natural and human-related issues as well as among stakeh...Land use/land cover represents the interactive and comprehensive influences between human activities and natural conditions,leading to potential conflicts among natural and human-related issues as well as among stakeholders.This study introduced economic standards for farmers.A hybrid approach(CA-ABM)of cellular automaton(CA)and an agent-based model(ABM)was developed to effectively deal with social and land-use synergic issues to examine human–environment interactions and projections of land-use conversions for a humid basin in south China.Natural attributes and socioeconomic data were used to analyze land use/land cover and its drivers of change.The major modules of the CA-ABM are initialization,migration,assets,land suitability,and land-use change decisions.Empirical estimates of the factors influencing the urban land-use conversion probability were captured using parameters based on a spatial logistic regression(SLR)model.Simultaneously,multicriteria evaluation(MCE)and Markov models were introduced to obtain empirical estimates of the factors affecting the probability of ecological land conversion.An agent-based CA-SLR-MCE-Markov(ABCSMM)land-use conversion model was proposed to explore the impacts of policies on land-use conversion.This model can reproduce observed land-use patterns and provide links for forest transition and urban expansion to land-use decisions and ecosystem services.The results demonstrated land-use simulations under multi-policy scenarios,revealing the usefulness of the model for normative research on land-use management.展开更多
Cellular senescence is the results of aging and age-related diseases,and the development of anti-aging methods may improve health and extend longevity.The natural flavonol fisetin has been shown to antagonize senescen...Cellular senescence is the results of aging and age-related diseases,and the development of anti-aging methods may improve health and extend longevity.The natural flavonol fisetin has been shown to antagonize senescence in vitro and increases longevity in vivo,but has poor water solubility and limited bioavailability.In this study,a food-grade and senescent cell-targeted delivery system for fisetin was developed based on whey protein isolate-galactooligosaccharides(WPI-GOS)Maillard conjugate,which could recognize senescence associatedβ-galactosidase in senescent cells.The fisetin nanoparticles possessed a high encapsulation efficiency,excellent dispersibility in water,good storage stability and well biocompatibility.Moreover,they could effectively accumulate and retain in senescent cells with excellent senescent cell-targeting efficacy,and inhibit the oxidative stress-induced cellular senescence in vitro.Thus,this novel nanoparticle system based on WPI-GOS Maillard conjugate showed promise to deliver hydrophobic bioactive ingredients like fisetin to senescent cells to improve their bioavailability and anti-senescence effect.展开更多
Due to the fact that a memristor with memory properties is an ideal electronic component for implementation of the artificial neural synaptic function,a brand-new tristable locally active memristor model is first prop...Due to the fact that a memristor with memory properties is an ideal electronic component for implementation of the artificial neural synaptic function,a brand-new tristable locally active memristor model is first proposed in this paper.Here,a novel four-dimensional fractional-order memristive cellular neural network(FO-MCNN)model with hidden attractors is constructed to enhance the engineering feasibility of the original CNN model and its performance.Then,its hardware circuit implementation and complicated dynamic properties are investigated on multi-simulation platforms.Subsequently,it is used toward secure communication application scenarios.Taking it as the pseudo-random number generator(PRNG),a new privacy image security scheme is designed based on the adaptive sampling rate compressive sensing(ASR-CS)model.Eventually,the simulation analysis and comparative experiments manifest that the proposed data encryption scheme possesses strong immunity against various security attack models and satisfactory compression performance.展开更多
Cellular structures are commonly used to design energy-absorbing structures,and origami structures are becominga prevalent method of cellular structure design.This paper proposes a foldable cellular structure based on...Cellular structures are commonly used to design energy-absorbing structures,and origami structures are becominga prevalent method of cellular structure design.This paper proposes a foldable cellular structure based on theWaterbomb origami pattern.The geometrical configuration of this structure is described.Quasi-static compressiontests of the origami tube cell of this cellular structure are conducted,and load-displacement relationship curvesare obtained.Numerical simulations are carried out to analyze the effects of aspect ratio,folding angle,thicknessand number of layers of origami tubes on initial peak force and specific energy absorption(SEA).Calculationformulas for initial peak force and SEA are obtained by the multiple linear regression method.The degree ofinfluence of each parameter on the mechanical properties of the single-layer tube cell is compared.The resultsshow that the cellular structure exhibits negative stiffness and periodic load-bearing capacity,as well as foldingangle has the most significant effect on the load-bearing and energy-absorbing capacity.By adjusting the designparameters,the stiffness,load-bearing capacity and energy absorption capacity of this cellular structure can beadjusted,which shows the programmable mechanical properties of this cellular structure.The foldability andthe smooth periodic load-bearing capacity give the structure potential for application as an energy-absorbing structure.展开更多
The evolution of microstructure during hot deformation is key to achieving good mechanical properties in aluminum alloys.We have developed a cellular automaton(CA) based model to simulate the microstructural evolution...The evolution of microstructure during hot deformation is key to achieving good mechanical properties in aluminum alloys.We have developed a cellular automaton(CA) based model to simulate the microstructural evolution in 7075 aluminum alloy during hot deformation.Isothermal compression tests were conducted to obtain material parameters for 7075 aluminum alloy,leading to the establishment of models for dislocation density,nucleation of recrystallized grains,and grain growth.Integrating these aspects with grain topological deformation,our CA model effectively predicts flow stress,dynamic recrystallization(DRX) volume fraction,and average grain size under diverse deformation conditions.A systematic comparison was made between electron back scattered diffraction(EBSD) maps and CA model simulated under different deformation temperatures(573 to 723 K),strain rates(0.001 to 1 s^(-1)),and strain amounts(30% to 70%).These analyses indicate that large strain,high temperature,and low strain rate facilitate dynamic recrystallization and grain refinement.The results from the CA model show good accuracy and predictive capability,with experimental error within 10%.展开更多
UAV-aided cellular networks,millimeter wave(mm-wave) communications and multi-antenna techniques are viewed as promising components of the solution for beyond-5G(B5G) and even 6G communications.By leveraging the power...UAV-aided cellular networks,millimeter wave(mm-wave) communications and multi-antenna techniques are viewed as promising components of the solution for beyond-5G(B5G) and even 6G communications.By leveraging the power of stochastic geometry,this paper aims at providing an effective framework for modeling and analyzing a UAV-aided heterogeneous cellular network,where the terrestrial base stations(TBSs) and the UAV base stations(UBSs) coexist,and the UBSs are provided with mm-wave and multi-antenna techniques.By modeling the TBSs as a PPP and the UBSs as a Matern hard-core point process of type Ⅱ(MPH-Ⅱ),approximated but accurate analytical results for the average rate of the typical user of both tiers are derived through an approximation method based on the mean interference-to-signal ratio(MISR) gain.The influence of some relevant parameters is discussed in detail,and some insights into the network deployment and optimization are revealed.Numerical results show that some trade-offs are worthy of being considered,such as the antenna array size,the altitude of the UAVs and the power control factor of the UBSs.展开更多
To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlin...To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.展开更多
基金supported in part by the National Natural Science Foundation of China(61931015,62071335)in part by the Natural Science Foundation of Hubei Province of China(2021CFA002)+2 种基金in part by the Fundamental Research Funds for the Central Universitiesin part by the Technological Innovation Project of Hubei Province of China(2019AAA061)in part by the Science and Technology Program of Shenzhen(JCYJ20170818112037398).
文摘In cellular systems,establishing the initial symbol timing of potential preambles is the first step of a cell search.The envelope fluctuation of the downlink signal hinders the successful timing of conventional symbol timing methods.To solve this problem,a hybrid timing strategy is proposed with two novel detectors,namely the normalized replica-based detector and normalized differential detector.The strategy first detects all potential preambles via the normalized replica-based detector and then employs the normalized differential detector to verify the target preamble,which comes from the target cell and has the highest power.The strategy is unaffected by envelope fluctuation and has computational complexity comparable to that of conventional methods.Simu-lations and real-data tests show that the hybrid timing strategy is robust and practical for initial symbol timing.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2231100)+1 种基金the Shanghai Pujiang Program (Grant No.08PJ14057)the Graduate Student Innovation Foundation of Shanghai University (Grant No.SHUCX080151)
文摘Recently, the multi-hop cellular networks have been widely studied in order to enhance the cell performances such as the cell capacity. While most of these works merely use the multi-hop methods instead of direct transmission without considering the co-channel inter-cell interference, signal transmission mode and the effects of the number of antennas. With the consideration of above important elements, this paper proposed an improved cellular system with multi-relay amplifies-andforward (AF) cooperative transmission scheme and the corresponding capacity expression is derived under the corresponding environment. By using the potential space diversity and selecting relays based on maximizing the capacity, the cellular system capacity can be improved effectively. The simulation results show that with the assistance of optimal selected relays, the improved cooperative cellular system capacity with multi-relay AF transmission scheme performs better than single-hop cellular system.
基金Sponsored by State Key Program of National Natural Science of China(Grant No.60832009)Natural Science Foundation of Beijing,China(Grant No.4102044)+1 种基金Innovative Project for Young Researchers in Central Higher Education Institutions,China(Grant No.2009RC0119New Generation of Broadband Wireless Mobile Communication Networks of Major Projects of National Science and Technology(Grant No.2009ZX03003-003-01)
文摘Within a cell of cellular system,cooperative relay technique can improve the performance of multicast efficiently,but it can cause the stream frequent interruptions because of the mobility of relay terminals.A video layered cooperative relay strategy is proposed to guarantee the continuity of multicast stream and retain high-bandwidth of the cooperative relay channel.Based on the capacity analysis for layered relay channel in the strategy,the optimal power allocation is studied to maximize capacity.After analyzing and optimizing the capacity in abstract models,the study is extended to a non-fading and a Gaussian wireless channel model to satisfy the scenario of cellular system.Giving the relay nodes position or distribution of noise power,the obtained results can determine the optimal power allocation among the transmitter and relay nodes.At last,the simulation results show that the strategy and its optimal power allocation have a significant improvement on the performance.
基金supported by the Shanghai Pujiang Program (Grant No.08PJ14057)the Science Foundation of Science and Technology Commission of Shanghai Municipality (Grant No.08220510900)
文摘In this paper, an asynchronous cooperative cellular system applied with space-time block coding (STBC) is investigated. A signal detector is proposed based on parallel interference cancellation (PIC), to cancel the inter-symbol interference (ISI) caused by the imperfect synchronization. Simulation results show that the proposed PIC detector can effiectively suppress the ISI, but there is still a comparatively high error floor, due to the co-channel interference (CCI) of the cellular system.
文摘It is known that dynamic channel assignment(D CA ) strategy outperforms the fixed channel assignment(FCA) strategy in omni-direc tional antenna cellular systems. One of the most important methods used in DCA w as channel borrowing. But with the emergence of cell sectorization and spatial d ivision multiple access(SDMA) which are used to increase the capacity of cel lular systems, the channel assignment faces a series of new problems. In this pa per, a dynamic channel allocation scheme based on sectored cellular systems is p roposed. By introducing intra-cell channel borrowing (borrowing channels from n eighboring sectors) and inter-cell channel borrowing (borrowing channels from n eighboring cells) methods, previous DCA strategies, including compact pattern ba sed channel borrowing(CPCB) and greedy based dynamic channel assignment(GDCA) schemes proposed by the author, are improved significantly. The computer simu lation shows that either intra-cell borrowing scheme or inter-cell borrowing s cheme is efficient enough to uniform and non-uniform traffic service distributi ons.
文摘The rapid developing of the fourth generation(4G)wireless communications has aroused tremendous demands for high speed data transmission due to the dissemination of various types of the intelligent user terminals as well as the wireless multi-media services.It is predicted that the network throughput will increase
基金This work was funded by the High- tech Research and Development Program of China (863 Program) under Grant 2006AA01Z208.
文摘Multi-criteria handoff algorithms have been playing a more important role than the traditional handoff algorithms.In order to balance the satisfaction of users and the efficiency of networks,it is necessary to develop new technologies to improve the validity of handoff algorithms.Intelligent and optimized handoff algorithms in hybrid networks that integrate Ad hoc and mobile cellular systems are well-adaptive and robust.They are able to implement handoffs adaptively,according to specific multi-factors such as different Quality of Service(QoS)requirements,network states and mobile node conditions in the future hybrid networks.Therefore,these intelligent and optimized algorithms can make more effective handover decision,and accordingly improve the system’s performance.The future research will tackle intelligent or optimized vertical handoff algorithms for integrated Ad hoc and mobile cellular networks to improve their whole system performance.
基金supported in part by National Natural Science Foundation of China under Grants No.61379006,61401510,61501516,61471396 and 61521003Research and Development Program of China(863 Program)under Grant No.2014AA01A701The Open Research Fund of National Mobile Communications Research Laboratory,Southeast University under Grants No.2013D09
文摘This paper focuses on the problem of secure transmission in a cellular system. A full-duplex base station using artificial noise is adopted to improve both the uplink and downlink secrecy rate via pairing terminals which reverses the downlink and uplink of each other. We give the designs of artificial noise and the user's desired signal, and derive the pairing prin-ciple between terminals. Moreover, the influence of self-interference cancellation on secrecy rate is ex-plored. Simulation results show that the secrecy rate can get much better performance by adopting full-duplex artificial noise scheme and proposed pair-ing method. The downlink secrecy rate decreases with the distance between terminals. Besides the uplink secrecy rate is sensitive to the ability of self-interference cancellation.
基金National Natural Science Foundation of China under grant number (61872186,61872193)The National Natural Science Foundation of China for Youth (61201160, 61602263)+8 种基金The Natural Science Foundation of Jiangsu Province (BK20131377, BK20151507, BK20160916)The Natural science fund for colleges and universities in Jiangsu Province under Grants (16KJB510034)The six talent peaks project in Jiangsu Province (XYDXXJS-044)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (yx002001)The Jiangsu Overseas Research and Training Program for University Prominent Young and Middle-aged Teachers and PresidentsSponsored by NUPTSF (Grant Nos. NY212012, NY214065,NY216020)The Six Talented Eminence Foundation of Jiangsu Province (No. XYDXXJS-044)The 333 High-level Talents Training Project of Jiangsu ProvinceThe 1311 Talents Plan of NUPT and the China Postdoctoral Science Foundation (No. 2018M630590)
文摘This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighboring cells. It is shown that when using inter-cell relay, the number of calls in the congestion cell can be significantly increased. The congestion cell is divided into two parts. One is called non-relay area(NRA), in which a call directly communicates with the base station(BS) of a congested cell. The other is called relay area(RA), in which a call communicates with the BS of a neighboring cell through a relay station(RS). The two parts have different user-call densities. By adjusting the densities of two parts, we will maximize the number of supported calls inside a congested cell. The results show the benefits gained from inter-cell relay in congestion relief, which can reduce cell congestion by fully utilizing the available resources in the neighboring cells.
文摘Power control is an important technique in WCDMA mobile systems for both increasing system capacity and guaranteeing the required QoS (time delay and wireless link transmission quality) of multimedia services. The optimum power control for narrow band CDMA cellular systems is a problem of single threshold optimization. Because these systems have only one type of traffic and have the same QoS requirement. However, WCDMA mobile system should provide multimedia services and different types of traffic have different QoS requirements. Thus, the power control in WCDMA mobile systems isn't a problem of single threshold optimizing, but turns into the optimizing problem of multi-threshold. We analyze the power control problem in WCDMA cellular mobile systems and propose the optimum transmitter power control algorithm. Three criteria to optimize transmitter power levels of multi-thresholds based on grading the priority orders of multimedia services are proposed. Simulation results show that the proposed algorithms are more effective than conventional algorithms and can provide better performance for WCDMA cellular mobile systems.
基金National Science Fund for Creative ResearchGroups(No.60521002)Chinese NationalKey Technology R&D Program(No.2005BA908B02)Science Foundation ofShanghai Municipal Commission of Scienceand Technology,Chinese(No.05dz05802)
文摘This paper presented a scheme of relayed cellular mobile telecommunication network,which only employs fixed digital relays and not more than two-hop relay routes.Power saving potential of the network is deeply studied under the assumption of not occupying additional frequency bands(i.e.relays share the same frequency bands as used by the base stations).Theoretical analysis and simulation results have both shown that,with the same radio coverage requirement,the necessary effective transmission powers in such a relayed network have greatly decreased compared to conventional cellular network.
基金Supported by the National Natural Science Foundation of China (No.60002003) and National Hi-Tech Research and Development Project of China (No.2002AA123044).
文摘This paper presents an efficient Radio Resource Management (RRM) strategy for adaptive Orthogo-nal Frequency Division Multiplexing (OFDM) cellular systems. In the proposed strategy, only those users who have the same distance from their base stations can reuse a same subcarrier. This can guarantee the received Carrier-to-Interference ratio (C/I) of each subcarrier to be acceptable as required by system planning. Then by employing different modulation scheme on each subcarrier according to its received C/I, system spectral effi-ciency can be gracefully increased. Analytical and simulation results show that the spectral efficiency is im-proved by 40% without sacrificing the Bit Error Rate (BER) performance and call blocking probability and sys-tem capacity of the proposed strategy is better than conventional systems.
基金Supported by the State Key Program of National Natural Science Foundation of China (No. 60832009), Natural Science Foundation of Bcijing (No. 4102044), Innovative Project for Young Researchers in Central Higher Education Institutions, China (No. 2009RC0119) and New Generation of Broadband Wireless Mobile Communication Networks of Major Projects of National Science and Technology (No.2009ZX03003-003-01).
基金supported by the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2021ZT090543)the National Natural Science Foundation of China(U20A20117)the Key-Area Research and Development Program of Guangdong Province(2020B1111380003).
文摘Land use/land cover represents the interactive and comprehensive influences between human activities and natural conditions,leading to potential conflicts among natural and human-related issues as well as among stakeholders.This study introduced economic standards for farmers.A hybrid approach(CA-ABM)of cellular automaton(CA)and an agent-based model(ABM)was developed to effectively deal with social and land-use synergic issues to examine human–environment interactions and projections of land-use conversions for a humid basin in south China.Natural attributes and socioeconomic data were used to analyze land use/land cover and its drivers of change.The major modules of the CA-ABM are initialization,migration,assets,land suitability,and land-use change decisions.Empirical estimates of the factors influencing the urban land-use conversion probability were captured using parameters based on a spatial logistic regression(SLR)model.Simultaneously,multicriteria evaluation(MCE)and Markov models were introduced to obtain empirical estimates of the factors affecting the probability of ecological land conversion.An agent-based CA-SLR-MCE-Markov(ABCSMM)land-use conversion model was proposed to explore the impacts of policies on land-use conversion.This model can reproduce observed land-use patterns and provide links for forest transition and urban expansion to land-use decisions and ecosystem services.The results demonstrated land-use simulations under multi-policy scenarios,revealing the usefulness of the model for normative research on land-use management.
基金supported by Dalian Youth Science and Technology Star Project(2020RQ121)the National Science Fund for Distinguished Young Scholars of China(31925031)+1 种基金Doctoral Scientific Research Foundation of Liaoning Province(2020-BS-211)Liaoning Province Education Administration(J2020101)。
文摘Cellular senescence is the results of aging and age-related diseases,and the development of anti-aging methods may improve health and extend longevity.The natural flavonol fisetin has been shown to antagonize senescence in vitro and increases longevity in vivo,but has poor water solubility and limited bioavailability.In this study,a food-grade and senescent cell-targeted delivery system for fisetin was developed based on whey protein isolate-galactooligosaccharides(WPI-GOS)Maillard conjugate,which could recognize senescence associatedβ-galactosidase in senescent cells.The fisetin nanoparticles possessed a high encapsulation efficiency,excellent dispersibility in water,good storage stability and well biocompatibility.Moreover,they could effectively accumulate and retain in senescent cells with excellent senescent cell-targeting efficacy,and inhibit the oxidative stress-induced cellular senescence in vitro.Thus,this novel nanoparticle system based on WPI-GOS Maillard conjugate showed promise to deliver hydrophobic bioactive ingredients like fisetin to senescent cells to improve their bioavailability and anti-senescence effect.
文摘Due to the fact that a memristor with memory properties is an ideal electronic component for implementation of the artificial neural synaptic function,a brand-new tristable locally active memristor model is first proposed in this paper.Here,a novel four-dimensional fractional-order memristive cellular neural network(FO-MCNN)model with hidden attractors is constructed to enhance the engineering feasibility of the original CNN model and its performance.Then,its hardware circuit implementation and complicated dynamic properties are investigated on multi-simulation platforms.Subsequently,it is used toward secure communication application scenarios.Taking it as the pseudo-random number generator(PRNG),a new privacy image security scheme is designed based on the adaptive sampling rate compressive sensing(ASR-CS)model.Eventually,the simulation analysis and comparative experiments manifest that the proposed data encryption scheme possesses strong immunity against various security attack models and satisfactory compression performance.
基金partially supported by the National Key R&D Program of China(Grant No.2022YFB2602700)the National Natural Science Foundation of China(Grant No.52378216)+1 种基金the National Natural Science Foundation of China for Excellent Young Scientists Fundthe Fundamental Research Funds for the Central Universities(Grant No.2022CDJKYJH052).
文摘Cellular structures are commonly used to design energy-absorbing structures,and origami structures are becominga prevalent method of cellular structure design.This paper proposes a foldable cellular structure based on theWaterbomb origami pattern.The geometrical configuration of this structure is described.Quasi-static compressiontests of the origami tube cell of this cellular structure are conducted,and load-displacement relationship curvesare obtained.Numerical simulations are carried out to analyze the effects of aspect ratio,folding angle,thicknessand number of layers of origami tubes on initial peak force and specific energy absorption(SEA).Calculationformulas for initial peak force and SEA are obtained by the multiple linear regression method.The degree ofinfluence of each parameter on the mechanical properties of the single-layer tube cell is compared.The resultsshow that the cellular structure exhibits negative stiffness and periodic load-bearing capacity,as well as foldingangle has the most significant effect on the load-bearing and energy-absorbing capacity.By adjusting the designparameters,the stiffness,load-bearing capacity and energy absorption capacity of this cellular structure can beadjusted,which shows the programmable mechanical properties of this cellular structure.The foldability andthe smooth periodic load-bearing capacity give the structure potential for application as an energy-absorbing structure.
基金Funded by the Central Government Guides Local Funds for Science and Technology Development(No.YDZJSX20231A045)the Fundamental Research Program of Shanxi Province(Nos.202103021223288 and 202103021224282)。
文摘The evolution of microstructure during hot deformation is key to achieving good mechanical properties in aluminum alloys.We have developed a cellular automaton(CA) based model to simulate the microstructural evolution in 7075 aluminum alloy during hot deformation.Isothermal compression tests were conducted to obtain material parameters for 7075 aluminum alloy,leading to the establishment of models for dislocation density,nucleation of recrystallized grains,and grain growth.Integrating these aspects with grain topological deformation,our CA model effectively predicts flow stress,dynamic recrystallization(DRX) volume fraction,and average grain size under diverse deformation conditions.A systematic comparison was made between electron back scattered diffraction(EBSD) maps and CA model simulated under different deformation temperatures(573 to 723 K),strain rates(0.001 to 1 s^(-1)),and strain amounts(30% to 70%).These analyses indicate that large strain,high temperature,and low strain rate facilitate dynamic recrystallization and grain refinement.The results from the CA model show good accuracy and predictive capability,with experimental error within 10%.
基金supported by National Natural Science Foundation of China (No.62001135)the Joint funds for Regional Innovation and Development of the National Natural Science Foundation of China(No.U21A20449)the Beijing Natural Science Foundation Haidian Original Innovation Joint Fund (No.L232002)
文摘UAV-aided cellular networks,millimeter wave(mm-wave) communications and multi-antenna techniques are viewed as promising components of the solution for beyond-5G(B5G) and even 6G communications.By leveraging the power of stochastic geometry,this paper aims at providing an effective framework for modeling and analyzing a UAV-aided heterogeneous cellular network,where the terrestrial base stations(TBSs) and the UAV base stations(UBSs) coexist,and the UBSs are provided with mm-wave and multi-antenna techniques.By modeling the TBSs as a PPP and the UBSs as a Matern hard-core point process of type Ⅱ(MPH-Ⅱ),approximated but accurate analytical results for the average rate of the typical user of both tiers are derived through an approximation method based on the mean interference-to-signal ratio(MISR) gain.The influence of some relevant parameters is discussed in detail,and some insights into the network deployment and optimization are revealed.Numerical results show that some trade-offs are worthy of being considered,such as the antenna array size,the altitude of the UAVs and the power control factor of the UBSs.
基金supported by the National Natural Science Foundation of China(No.62071354)the Key Research and Development Program of Shaanxi(No.2022ZDLGY05-08)supported by the ISN State Key Laboratory。
文摘To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.