This paper investigates the effective capacity of a point-to-point ultra-reliable low latency communication(URLLC)transmission over multiple parallel sub-channels at finite blocklength(FBL)with imperfect channel state...This paper investigates the effective capacity of a point-to-point ultra-reliable low latency communication(URLLC)transmission over multiple parallel sub-channels at finite blocklength(FBL)with imperfect channel state information(CSI).Based on reasonable assumptions and approximations,we derive the effective capacity as a function of the pilot length,decoding error probability,transmit power and the sub-channel number.Then we reveal significant impact of the above parameters on the effective capacity.A closed-form lower bound of the effective capacity is derived and an alternating optimization based algorithm is proposed to find the optimal pilot length and decoding error probability.Simulation results validate our theoretical analysis and show that the closedform lower bound is very tight.In addition,through the simulations of the optimized effective capacity,insights for pilot length and decoding error probability optimization are provided to evaluate the optimal parameters in realistic systems.展开更多
For Peer-to-Peer (P2P) streaming services in mobile networks, the selection of appropriate neighbour peers from candidate peers with demanding data is an important approach to improve Quality-of-Service (QoS). This pa...For Peer-to-Peer (P2P) streaming services in mobile networks, the selection of appropriate neighbour peers from candidate peers with demanding data is an important approach to improve Quality-of-Service (QoS). This paper proposes a novel Effective Capacity Peer Selection (ECPS) scheme based on effective capacity. In the ECPS scheme, the neighbour peer selection problem was modeled using the Multiple Attribute Decision Making (MADM) theory, which considered multiple factors of candidate peers, including Signal to Interference and Noise Ratio (SINR), residency time, power level, security, moving speed, and effective capacity. This model could increase the suitability of ECPS for wireless mobile environments. Then, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was used to solve the MADM problem and identify the preferred neighbour peers. Simulation results show that the ECPS scheme can improve the network throughput, reduce packet delay by about 82%, and almost double the packet delivery ratio of the mobile P2P streaming service.展开更多
As known that the effective capacity theory offers a methodology for exploring the performance limits in delay constrained wireless networks, this article considered a spectrum sharing cognitive radio （CR） system in...As known that the effective capacity theory offers a methodology for exploring the performance limits in delay constrained wireless networks, this article considered a spectrum sharing cognitive radio （CR） system in which CR users may access the spectrum allocated to primary users （PUs）. Particularly, the channel between the CR transmitter （CR-T） and the primary receiver and the channel between the CR-T and the CR receiver （CR-R） may undergo different fading types and arbitrary link power gains. This is referred to as asymmetric fading. The authors investigated the capacity gains achievable under a given delay quality-of-service （QoS） constraint in asymmetric fading channels. The closed-form expression for the effective capacity under an average received interference power constraint is obtained. The main results indicate that the effective capacity is sensitive to the fading types and link power gains. The fading parameters of the interference channel play a vital role in effective capacity for the looser delay constraints. However, the fading parameters of the CR channel play a decisive role in effective capacity for the more stringent delay constraints. Also, the impact of multiple PUs on the capacity gains under delay constraints has also been explored.展开更多
Unbalanced multi-stage logistics systems are optimized using an improved genetic algorithm based on the Prüfer number and the effective capacity coding. The improved decoding procedure uses the node capacity of t...Unbalanced multi-stage logistics systems are optimized using an improved genetic algorithm based on the Prüfer number and the effective capacity coding. The improved decoding procedure uses the node capacity of the logistics system as an important factor, which influences the decoding procedure. As a result, any Prüfer number produced stochastically can be decoded to a feasible logistics pattern, which matchs the node capacities of the logistics system. With effective capacity coding, an unbalanced logistics system can be converted to a set of balanced systems. The effective capacity coding was combined with the Prefer number to construct the chromosome for the new method to search the whole solution space of the unbalanced multi-stage logistics system. Simulation results show that the new method finds a better solution with less computational time than st-GA. Although using a little more memory, the new method is still an efficient and robust method for optimizing unbalanced multi-stage logistics systems.展开更多
Objective To determine the effect of the phosphodiesterase-5 inhibitor sildenafil compared with placebo on exercise capacity and clinical status in HFPEF. Design Multicenter, double-blind, placebo-controlled, paralle...Objective To determine the effect of the phosphodiesterase-5 inhibitor sildenafil compared with placebo on exercise capacity and clinical status in HFPEF. Design Multicenter, double-blind, placebo-controlled, parallel-group, randomized clinical trial of 216 sta- ble outpatients with HF, ejection fraction ≥ 50%, elevated N-terminal brain-type natriuretic peptide or elevat- ed invasively measured filling pressures, and reduced exercise capacity. Participants were randomized from October 2008 through February 2012 at 26 centers in North America. Follow-up was through August 30, 2012.展开更多
This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due ...This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due to the channel uncertainties caused by quantization error. Considering this, we propose a parameter named effective ergodic capacity rate (EECR), which denotes the capacity offset between finite rate feedback and perfect channel state information (CSI). The simulation results show that the derived approximated EECR is very tight to actual EECR. Based on the approximated EECR, an adaptive minimum bit feedback scheme is proposed, which can effectively reduce the overhead of feedback channel and the complexity of the system. The simulation results verify the effectiveness of the proposed scheme.展开更多
Recent experimental and theoretical studies show that energy efficiency, which measures the amount of infor- mation processed by a neuron with per unit of energy consumption, plays an important role in the evolution o...Recent experimental and theoretical studies show that energy efficiency, which measures the amount of infor- mation processed by a neuron with per unit of energy consumption, plays an important role in the evolution of neural systems. Here we calculate the information rates and energy efficieneies of the Hodgkin-Huxley （HH） neuron model at different temperatures in a noisy environment. It is found that both the information rate and energy efficiency are maximized by certain temperatures. Though the information rate and energy efficiency cannot be maximized simultaneously, the neuron holds a high information processing capacity at the tempera- ture corresponding to the maximal energy efficiency. Our results support the idea that the energy efficiency is a selective pressure that influences the evolution of nervous systems.展开更多
The lack of communication infrastructure in remote regions presents significant obstacles to gathering data from smart power sensors(SPSs)in smart grid networks.In such cases,a space-air-ground integrated network serv...The lack of communication infrastructure in remote regions presents significant obstacles to gathering data from smart power sensors(SPSs)in smart grid networks.In such cases,a space-air-ground integrated network serves as an effective emergency solution.This study addresses the challenge of optimizing the energy efficiency of data transmission fromSPSs to low Earth orbit(LEO)satellites through unmanned aerial vehicles(UAVs),considering both effective capacity and fronthaul link capacity constraints.Due to the non-convex nature of the problem,the objective function is reformulated,and a delay-aware energy-efficient power allocation and UAV trajectory design(DEPATD)algorithm is proposed as a two-loop approach.Since the inner loop remains non-convex,the block coordinate descent(BCD)method is employed to decompose it into three subproblems:power allocation for SPSs,power allocation for UAVs,and UAV trajectory design.The first two subproblems are solved using the Lagrangian dual method,while the third is addressed with the successive convex approximation(SCA)technique.By iteratively solving these subproblems,an efficient algorithm is developed to resolve the inner loop issue.Simulation results demonstrate that the energy efficiency of the proposed DEPATD algorithm improves by 4.02% compared to the benchmark algorithm when the maximum transmission power of the SPSs increases from 0.1 to 0.45W.展开更多
Hydrogen energy has gained widespread recognition for its environmentally friendly nature,high energy density and abundant resources,making it a promising energy carrier for a sustainable and clean energy society.Howe...Hydrogen energy has gained widespread recognition for its environmentally friendly nature,high energy density and abundant resources,making it a promising energy carrier for a sustainable and clean energy society.However,safe and efficient hydrogen storage remains a significant challenge due to its inherent leakiness and flammability.To overcome these challenges,alloys featuring body-centered cubic(BCC)structures have emerged as compelling candidates for hydrogen storage,owing to their exceptional capacity to achieve high-density hydrogen storage up to 3.8 wt%at ambient temperatures.Nonetheless,their practical application faces limited dehydriding capacity,complex activation processes,high costs and poor cyclic stability.Various modification strategies have been explored to overcome these limitations,including lattice regulation,element substitution,rare earth doping and heat treatment.This progress report presents an overview of the previous advancements to enhance five crucial aspects(high-V,medium-V,low-V,V-free and high-entropy alloys)in composition design and hydrogen storage properties within BCC-structured alloys.Subsequently,an in-depth analysis is conducted to examine the relationship between crystal structures and hydrogen storage properties specific to BCC-structured alloys,covering aspects such as composition,crystal structure,hydrogen storage capacity,enthalpy and entropy.Furthermore,this review explores current challenges in this field and outlines directions for future research.These insights provide valuable guidance for the design of innovative and cost-effective hydrogen storage alloys.展开更多
A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS...A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.展开更多
Quality of experience(Qo E), which is very critical for the experience of users in wireless networks, has been extensively studied. However, due to different human perceptions, quantifying the effective capacity of wi...Quality of experience(Qo E), which is very critical for the experience of users in wireless networks, has been extensively studied. However, due to different human perceptions, quantifying the effective capacity of wireless network subject to diverse Qo E is very difficult, which leads to many new challenges regarding Qo E guarantees in wireless networks. In this paper, we formulate the Qo E guarantees model for cellular wireless networks. Based on the model, we convert the effective capacity maximization problem into the equivalent convex optimization problem. Then, we develop the optimal Qo E-driven power allocation scheme, which can maximize the effective capacity. The obtained simulation results verified our proposed power allocation scheme, showing that the effective capacity can be significantly increased compared with that of traditional Qo E guarantees based schemes.展开更多
To provide a certain level of Quality of Service (QoS) guarantees for multiuser wireless downlink video streaming transmissions, we propose a multiuser scheduling scheme for QoS guarantees. It is based on the classic ...To provide a certain level of Quality of Service (QoS) guarantees for multiuser wireless downlink video streaming transmissions, we propose a multiuser scheduling scheme for QoS guarantees. It is based on the classic Queue-Length-Based (QLB)-rate maximum scheduling algorithm and integrated with the delay constraint and the packet priority drop. We use the large deviation principle and the effective capacity theory to construct a new analysis model to find each user's queue length threshold (delay constraint) violation probability. This probability corresponds to the upper bound of the packet drop probability, which indicates a certain level of statistical QoS guarantees. Then, we utilize the priority information of video packets and introduce the packet priority drop to further improve the quality perceived by each user. The simulation results show that the average Peak Signal to Noise Ratio (PSNR) value of the priority drop is 0.8 higher than that of the non-priority drop and the PSNR value of the most badly damaged video frame in the priority drop is on an average 4 higher than that of the non-priority drop.展开更多
To meet the booming development of diversified services and new applications in the future, the fifth-generation mobile conmmnication system （5G） has arisen. Resources are increasingly scarce in the @namic time-vary...To meet the booming development of diversified services and new applications in the future, the fifth-generation mobile conmmnication system （5G） has arisen. Resources are increasingly scarce in the @namic time-varying of 5G networks. Allocating resources effectively and ensuring quality of service （QoS） requirements of multi-seiwices come to be a research focus. In this paper, we utilize effective capacity to build a utility function with multi-QoS metrics, including rate, delay bound and packet loss ratio. Taking advantage of opportunity cost （OC）, we also propose a multi-QoS guaranteed resource allocation algm＇ithm for multi-services to consider the future condition of system. In the algorithm, according to different business characteristics and the theory of OC, we propose different selection conditions for QoS users and best effort （BE） users to choose more reasonable resources. Finally, simulation results show that our proposed algorithm achieves superior system utility and relatively better fairness in multi-service scenarios.展开更多
The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler bec...The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler because of its high spectral efficiency. The higher the frequencies of the RF signal, the lower the distance it travels in free space caused by path loss, and it is more easily absorbed by obstacles, which are needed for high-gain transmitters. The advantage of the physical properties of higher New Radio (NR) frequencies is that 5G can utilize more spectrum, more antennas, and higher-order modulation schemes. The massive antennas and radio frequency chains improve the implementation of the cost of 5G wireless communication systems and result in an intense mutual coupling effect among antennas because of the limited space for deploying antennas. The upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Two antennas that receive diversity gain models, the mutual coupling matrix, and the spacing antenna distance are built and analyzed. The impacts and affections of the antenna spacing the number of antennas, the quality-of-service (QoS) statistical exponent, and the number of independent incident directions on the upper effective capacity of 5G multimedia massive MIMO communication systems are analyzed. It is shown that for MIMO systems with compact transmit antenna arrays, the mutual coupling seriously degrades system capacity to mitigate the capacity degradation. In case of improvement in the mutual coupling by 99%, the system performance is kept stationary and enhances system capacity. However, the improvement of the mutual coupling is still about 87.5% today, which means the mutual coupling should be considered in 5G massive MIMO networks.展开更多
Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions ...Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions of their rice fields,because both information factors(combine harvester and field condition)impact the field capacity.The field capacity model was generated from combine harvesters with the Thai Hom Mali rice variety(KDML-105).Therefore,this study aimed to determine the prediction model for effective field capacity to combine harvesters when harvesting the Thai Hom Mali rice variety(KDML-105).The methods began by collecting data of 15 combine harvesters,such as field,crop,and machine conditions and operating times;to generate the prediction model for the KDML-105 variety.The prediction model was then validated using 12 combine harvesters that were collected similarly to the model creation.The results showed a root mean square error(RMSE)of 0.24 m^(2)/s for the model.The prediction model can be applied for farmers to select the proper combine harvesters and give their field conditions.展开更多
Along with natural disasters,the destruction of communication infrastructures leads to the congestion or failure of communication networks.Unmanned aerial vehicles(UAVs),which are with a high flexibility,can be employ...Along with natural disasters,the destruction of communication infrastructures leads to the congestion or failure of communication networks.Unmanned aerial vehicles(UAVs),which are with a high flexibility,can be employed as temporary base stations to establish emergency networks.To relieve the backhaul burden of UAVs,some imperative contents can be cached by terrestrial cache-enabled rescuers(CERs)and provide for victims with device-to-device(D2D)transmissions.To support the effectiveness and timeliness of emergency communication,the delay-bounded quality-of-service(QoS)requirement and network throughput are desired to be comprehensively considered,which imposes a new challenge for caching placement and CER deployment.In this paper,we focus on joint caching placement and CER deployment to maximize the effective capacity subject to delay-bounded QoS requirement.The overall non-convex problem is transformed into the caching placement and the CER deployment sub-problems.Then,we develop the QoS-aware caching placement scheme with fixed CER deployment density and obtain the QoS-aware CER deployment density with fixed caching placement.Based on the block-coordinate descent method,we also propose the joint caching placement and CER deployment scheme,which can not only effectively enhance average effective capacity but also guarantee the delay-bounded QoS requirement.Also,numerical simulations are conducted to show the performances of the proposed schemes.展开更多
This article considers a wireless network consisting of multiple sources that communicate with the corresponding destination utilizing a single half-duplex relay, whereas, the sources use the relay opportunistically. ...This article considers a wireless network consisting of multiple sources that communicate with the corresponding destination utilizing a single half-duplex relay, whereas, the sources use the relay opportunistically. By integrating the information theory with the concept of effective capacity, this article proposes a dynamic time allocation strategy over the wireless relay network that aims at maximizing the relay network throughput, subject to a given delay quality of service （QoS） constraint, where time division multiple access （TDMA） is applied in the relay network. The simulation results show that the proposed allocation strategy can significantly improve the effective capacity as compared to the traditional equal time allocation strategy.展开更多
Reconfigurable intelligent surfaces (RIS) play a vital role in meeting the growing demand for higher data rates and reliability in wireless systems. This study focuses on analyzing the performance of RIS systems to ga...Reconfigurable intelligent surfaces (RIS) play a vital role in meeting the growing demand for higher data rates and reliability in wireless systems. This study focuses on analyzing the performance of RIS systems to gain a deeper understanding of their potential.The paper presents a mathematical analysis of the RIS system,deriving closed-form formulae that express its characteristics including signal-to-noise ratio(SNR)distribution,ergodic and effective capacity,outage,and error probability. The obtained formulae are newly derived and unconditionally valid solutions. Numerical results demonstrate a close agreement between the derived formulae and MonteCarlo simulation outcomes.展开更多
Spectrum and energy resources are very important for the rapidly developing of thefifth generation(5G)wireless communication networks.Cognitive radio and energy harvesting technologies,which focus on the spectrum effi...Spectrum and energy resources are very important for the rapidly developing of thefifth generation(5G)wireless communication networks.Cognitive radio and energy harvesting technologies,which focus on the spectrum efficiency and the energy efficiency,respectively,can be jointly used for solving the scarcities of spectrum and energy in energy harvesting cognitive radio networks(EHCRNs),where the energy is absorbed from ambient space and spectrum is licensed to the primary users.However,how to guarantee the quality of service(QoS)for EHCRNs is still a challenging problem.In this paper,we develop the optimal power and rate adaptation scheme under statistical QoS provisioning for EHCRNs.In particular,we analyze the power constraints of EHCRNs.Then,we formulate the effective capacity maximization problem for EHCRNs,solving which we obtain the closedform of the optimal power allocation and rate adaptation scheme under different power constraints.Numerical analyses verify the effective capacity enhancement and validate the relationships among the effective capacity,the QoS exponent,the energy arrival rate,and the average interference power.展开更多
Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line...Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line may be altered according to the field conditions.Tractor drivers usually use an angle close to maximum in order to decrease the tillage depth,consequently decreasing power requirements,without considering the tillage quality and the impact on the soil properties.This experiment was conducted at the College of Agricultural Studies farm of Sudan University of Science and Technology to study the effects of three tilt angles(15°,20°and 25°)on soil bulk density,mean weight diameter,wheel slippage,work rate(or effective field capacity)and soil volume disturbed using mounted disk plough.The nature of soil on the farm found to be light clay.The theoretical forward speed was maintained at 6 km/h.The results showed that increasing tilt angle of the plough significantly(p<0.05)increased the bulk density,mean weight diameter and field capacity while significantly decreasing the tractor wheel slippage and soil volume disturbance.展开更多
基金supported by the National Natural Science Foundation of China under grant 61941106。
文摘This paper investigates the effective capacity of a point-to-point ultra-reliable low latency communication(URLLC)transmission over multiple parallel sub-channels at finite blocklength(FBL)with imperfect channel state information(CSI).Based on reasonable assumptions and approximations,we derive the effective capacity as a function of the pilot length,decoding error probability,transmit power and the sub-channel number.Then we reveal significant impact of the above parameters on the effective capacity.A closed-form lower bound of the effective capacity is derived and an alternating optimization based algorithm is proposed to find the optimal pilot length and decoding error probability.Simulation results validate our theoretical analysis and show that the closedform lower bound is very tight.In addition,through the simulations of the optimized effective capacity,insights for pilot length and decoding error probability optimization are provided to evaluate the optimal parameters in realistic systems.
基金supported in part by the National Natural Science Foundation of China under Grant No. 60902047the Fundamental Research Funds for the Central Universities under Grant No. BUPT2013RC0111
文摘For Peer-to-Peer (P2P) streaming services in mobile networks, the selection of appropriate neighbour peers from candidate peers with demanding data is an important approach to improve Quality-of-Service (QoS). This paper proposes a novel Effective Capacity Peer Selection (ECPS) scheme based on effective capacity. In the ECPS scheme, the neighbour peer selection problem was modeled using the Multiple Attribute Decision Making (MADM) theory, which considered multiple factors of candidate peers, including Signal to Interference and Noise Ratio (SINR), residency time, power level, security, moving speed, and effective capacity. This model could increase the suitability of ECPS for wireless mobile environments. Then, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was used to solve the MADM problem and identify the preferred neighbour peers. Simulation results show that the ECPS scheme can improve the network throughput, reduce packet delay by about 82%, and almost double the packet delivery ratio of the mobile P2P streaming service.
基金supported by the National Natural Science Foundation of China (61171029)
文摘As known that the effective capacity theory offers a methodology for exploring the performance limits in delay constrained wireless networks, this article considered a spectrum sharing cognitive radio （CR） system in which CR users may access the spectrum allocated to primary users （PUs）. Particularly, the channel between the CR transmitter （CR-T） and the primary receiver and the channel between the CR-T and the CR receiver （CR-R） may undergo different fading types and arbitrary link power gains. This is referred to as asymmetric fading. The authors investigated the capacity gains achievable under a given delay quality-of-service （QoS） constraint in asymmetric fading channels. The closed-form expression for the effective capacity under an average received interference power constraint is obtained. The main results indicate that the effective capacity is sensitive to the fading types and link power gains. The fading parameters of the interference channel play a vital role in effective capacity for the looser delay constraints. However, the fading parameters of the CR channel play a decisive role in effective capacity for the more stringent delay constraints. Also, the impact of multiple PUs on the capacity gains under delay constraints has also been explored.
文摘Unbalanced multi-stage logistics systems are optimized using an improved genetic algorithm based on the Prüfer number and the effective capacity coding. The improved decoding procedure uses the node capacity of the logistics system as an important factor, which influences the decoding procedure. As a result, any Prüfer number produced stochastically can be decoded to a feasible logistics pattern, which matchs the node capacities of the logistics system. With effective capacity coding, an unbalanced logistics system can be converted to a set of balanced systems. The effective capacity coding was combined with the Prefer number to construct the chromosome for the new method to search the whole solution space of the unbalanced multi-stage logistics system. Simulation results show that the new method finds a better solution with less computational time than st-GA. Although using a little more memory, the new method is still an efficient and robust method for optimizing unbalanced multi-stage logistics systems.
文摘Objective To determine the effect of the phosphodiesterase-5 inhibitor sildenafil compared with placebo on exercise capacity and clinical status in HFPEF. Design Multicenter, double-blind, placebo-controlled, parallel-group, randomized clinical trial of 216 sta- ble outpatients with HF, ejection fraction ≥ 50%, elevated N-terminal brain-type natriuretic peptide or elevat- ed invasively measured filling pressures, and reduced exercise capacity. Participants were randomized from October 2008 through February 2012 at 26 centers in North America. Follow-up was through August 30, 2012.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2006AA01Z272 and 2009AA02Z412)the Beijing Municipal Science & Technology Commission(Grant No.D08080100620802)
文摘This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due to the channel uncertainties caused by quantization error. Considering this, we propose a parameter named effective ergodic capacity rate (EECR), which denotes the capacity offset between finite rate feedback and perfect channel state information (CSI). The simulation results show that the derived approximated EECR is very tight to actual EECR. Based on the approximated EECR, an adaptive minimum bit feedback scheme is proposed, which can effectively reduce the overhead of feedback channel and the complexity of the system. The simulation results verify the effectiveness of the proposed scheme.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11105062,11275003,11265014 and 11275084the Fundamental Research Funds for the Central Universities under Grant No LZUJBKY-2015-119
文摘Recent experimental and theoretical studies show that energy efficiency, which measures the amount of infor- mation processed by a neuron with per unit of energy consumption, plays an important role in the evolution of neural systems. Here we calculate the information rates and energy efficieneies of the Hodgkin-Huxley （HH） neuron model at different temperatures in a noisy environment. It is found that both the information rate and energy efficiency are maximized by certain temperatures. Though the information rate and energy efficiency cannot be maximized simultaneously, the neuron holds a high information processing capacity at the tempera- ture corresponding to the maximal energy efficiency. Our results support the idea that the energy efficiency is a selective pressure that influences the evolution of nervous systems.
基金Supported by the Self-funded Research Project of Beijing FibrLink Communications Co.Ltd.“Research on Key Technologies forUnifiedManagement of Air-to-Earth Integrated CommunicationNetworks(546826230034).”。
文摘The lack of communication infrastructure in remote regions presents significant obstacles to gathering data from smart power sensors(SPSs)in smart grid networks.In such cases,a space-air-ground integrated network serves as an effective emergency solution.This study addresses the challenge of optimizing the energy efficiency of data transmission fromSPSs to low Earth orbit(LEO)satellites through unmanned aerial vehicles(UAVs),considering both effective capacity and fronthaul link capacity constraints.Due to the non-convex nature of the problem,the objective function is reformulated,and a delay-aware energy-efficient power allocation and UAV trajectory design(DEPATD)algorithm is proposed as a two-loop approach.Since the inner loop remains non-convex,the block coordinate descent(BCD)method is employed to decompose it into three subproblems:power allocation for SPSs,power allocation for UAVs,and UAV trajectory design.The first two subproblems are solved using the Lagrangian dual method,while the third is addressed with the successive convex approximation(SCA)technique.By iteratively solving these subproblems,an efficient algorithm is developed to resolve the inner loop issue.Simulation results demonstrate that the energy efficiency of the proposed DEPATD algorithm improves by 4.02% compared to the benchmark algorithm when the maximum transmission power of the SPSs increases from 0.1 to 0.45W.
基金supported by the National Key R&D Program of China(No.2022YFB3504700)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0400304)the Research Fund of Key Laboratory of Rare Earths,Chinese Academy of Sciences(No.E32PF00116).
文摘Hydrogen energy has gained widespread recognition for its environmentally friendly nature,high energy density and abundant resources,making it a promising energy carrier for a sustainable and clean energy society.However,safe and efficient hydrogen storage remains a significant challenge due to its inherent leakiness and flammability.To overcome these challenges,alloys featuring body-centered cubic(BCC)structures have emerged as compelling candidates for hydrogen storage,owing to their exceptional capacity to achieve high-density hydrogen storage up to 3.8 wt%at ambient temperatures.Nonetheless,their practical application faces limited dehydriding capacity,complex activation processes,high costs and poor cyclic stability.Various modification strategies have been explored to overcome these limitations,including lattice regulation,element substitution,rare earth doping and heat treatment.This progress report presents an overview of the previous advancements to enhance five crucial aspects(high-V,medium-V,low-V,V-free and high-entropy alloys)in composition design and hydrogen storage properties within BCC-structured alloys.Subsequently,an in-depth analysis is conducted to examine the relationship between crystal structures and hydrogen storage properties specific to BCC-structured alloys,covering aspects such as composition,crystal structure,hydrogen storage capacity,enthalpy and entropy.Furthermore,this review explores current challenges in this field and outlines directions for future research.These insights provide valuable guidance for the design of innovative and cost-effective hydrogen storage alloys.
基金The National Science and Technology M ajor Project(No.2012ZX03004005-003)the National Natural Science Foundation of China(No.61171081,61201175)the Research Fund of National M obile Communications Research Laboratory of Southeast University(No.2014A03)
文摘A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.
基金supported in part by the National Natural Science Foundation of China(Nos.61771368 and 61671347)Young Elite Scientists Sponsorship Program by CAST(2016QNRC001)
文摘Quality of experience(Qo E), which is very critical for the experience of users in wireless networks, has been extensively studied. However, due to different human perceptions, quantifying the effective capacity of wireless network subject to diverse Qo E is very difficult, which leads to many new challenges regarding Qo E guarantees in wireless networks. In this paper, we formulate the Qo E guarantees model for cellular wireless networks. Based on the model, we convert the effective capacity maximization problem into the equivalent convex optimization problem. Then, we develop the optimal Qo E-driven power allocation scheme, which can maximize the effective capacity. The obtained simulation results verified our proposed power allocation scheme, showing that the effective capacity can be significantly increased compared with that of traditional Qo E guarantees based schemes.
基金supported by a Gift Funding from Huawei Technologies and Science Foundation of Education Bureau of Sichuan Province, China, under Grant No.10ZB019
文摘To provide a certain level of Quality of Service (QoS) guarantees for multiuser wireless downlink video streaming transmissions, we propose a multiuser scheduling scheme for QoS guarantees. It is based on the classic Queue-Length-Based (QLB)-rate maximum scheduling algorithm and integrated with the delay constraint and the packet priority drop. We use the large deviation principle and the effective capacity theory to construct a new analysis model to find each user's queue length threshold (delay constraint) violation probability. This probability corresponds to the upper bound of the packet drop probability, which indicates a certain level of statistical QoS guarantees. Then, we utilize the priority information of video packets and introduce the packet priority drop to further improve the quality perceived by each user. The simulation results show that the average Peak Signal to Noise Ratio (PSNR) value of the priority drop is 0.8 higher than that of the non-priority drop and the PSNR value of the most badly damaged video frame in the priority drop is on an average 4 higher than that of the non-priority drop.
基金supported by the National Science and Technology Major Project under Grant No.2016ZX03001009-003the Nature and Science Foundation of China under Grants Nos.61471068111 Project of China B16006
文摘To meet the booming development of diversified services and new applications in the future, the fifth-generation mobile conmmnication system （5G） has arisen. Resources are increasingly scarce in the @namic time-varying of 5G networks. Allocating resources effectively and ensuring quality of service （QoS） requirements of multi-seiwices come to be a research focus. In this paper, we utilize effective capacity to build a utility function with multi-QoS metrics, including rate, delay bound and packet loss ratio. Taking advantage of opportunity cost （OC）, we also propose a multi-QoS guaranteed resource allocation algm＇ithm for multi-services to consider the future condition of system. In the algorithm, according to different business characteristics and the theory of OC, we propose different selection conditions for QoS users and best effort （BE） users to choose more reasonable resources. Finally, simulation results show that our proposed algorithm achieves superior system utility and relatively better fairness in multi-service scenarios.
文摘The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler because of its high spectral efficiency. The higher the frequencies of the RF signal, the lower the distance it travels in free space caused by path loss, and it is more easily absorbed by obstacles, which are needed for high-gain transmitters. The advantage of the physical properties of higher New Radio (NR) frequencies is that 5G can utilize more spectrum, more antennas, and higher-order modulation schemes. The massive antennas and radio frequency chains improve the implementation of the cost of 5G wireless communication systems and result in an intense mutual coupling effect among antennas because of the limited space for deploying antennas. The upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Two antennas that receive diversity gain models, the mutual coupling matrix, and the spacing antenna distance are built and analyzed. The impacts and affections of the antenna spacing the number of antennas, the quality-of-service (QoS) statistical exponent, and the number of independent incident directions on the upper effective capacity of 5G multimedia massive MIMO communication systems are analyzed. It is shown that for MIMO systems with compact transmit antenna arrays, the mutual coupling seriously degrades system capacity to mitigate the capacity degradation. In case of improvement in the mutual coupling by 99%, the system performance is kept stationary and enhances system capacity. However, the improvement of the mutual coupling is still about 87.5% today, which means the mutual coupling should be considered in 5G massive MIMO networks.
文摘Farmers have to finish their harvesting with high efficiency,because of time and cost.However,farmers are lacking knowledge and information required for selecting suitable combine harvesters and giving the conditions of their rice fields,because both information factors(combine harvester and field condition)impact the field capacity.The field capacity model was generated from combine harvesters with the Thai Hom Mali rice variety(KDML-105).Therefore,this study aimed to determine the prediction model for effective field capacity to combine harvesters when harvesting the Thai Hom Mali rice variety(KDML-105).The methods began by collecting data of 15 combine harvesters,such as field,crop,and machine conditions and operating times;to generate the prediction model for the KDML-105 variety.The prediction model was then validated using 12 combine harvesters that were collected similarly to the model creation.The results showed a root mean square error(RMSE)of 0.24 m^(2)/s for the model.The prediction model can be applied for farmers to select the proper combine harvesters and give their field conditions.
基金This work was supported in part by National Natural Science Foundation of China(Nos.61771368 and 61671347)the Young Elite Scientists Sponsorship Program by CAST(No.2016QNRC001)+1 种基金the Youth Talent Support Fund of Science and Technology of Shaanxi Province(No.2018KJXX-025)Part of this work has been accepted by the IEEE Conference on Computer Communications Workshops(INFOCOM Workshop on Intelligent Wireless Emergency Communications Networks),Toronto,Canada,2020[1].
文摘Along with natural disasters,the destruction of communication infrastructures leads to the congestion or failure of communication networks.Unmanned aerial vehicles(UAVs),which are with a high flexibility,can be employed as temporary base stations to establish emergency networks.To relieve the backhaul burden of UAVs,some imperative contents can be cached by terrestrial cache-enabled rescuers(CERs)and provide for victims with device-to-device(D2D)transmissions.To support the effectiveness and timeliness of emergency communication,the delay-bounded quality-of-service(QoS)requirement and network throughput are desired to be comprehensively considered,which imposes a new challenge for caching placement and CER deployment.In this paper,we focus on joint caching placement and CER deployment to maximize the effective capacity subject to delay-bounded QoS requirement.The overall non-convex problem is transformed into the caching placement and the CER deployment sub-problems.Then,we develop the QoS-aware caching placement scheme with fixed CER deployment density and obtain the QoS-aware CER deployment density with fixed caching placement.Based on the block-coordinate descent method,we also propose the joint caching placement and CER deployment scheme,which can not only effectively enhance average effective capacity but also guarantee the delay-bounded QoS requirement.Also,numerical simulations are conducted to show the performances of the proposed schemes.
基金Shanghai STCSM Project (07dz22023)Shanghai Postdoctoral Scientific Program (07R214158)
文摘This article considers a wireless network consisting of multiple sources that communicate with the corresponding destination utilizing a single half-duplex relay, whereas, the sources use the relay opportunistically. By integrating the information theory with the concept of effective capacity, this article proposes a dynamic time allocation strategy over the wireless relay network that aims at maximizing the relay network throughput, subject to a given delay quality of service （QoS） constraint, where time division multiple access （TDMA） is applied in the relay network. The simulation results show that the proposed allocation strategy can significantly improve the effective capacity as compared to the traditional equal time allocation strategy.
文摘Reconfigurable intelligent surfaces (RIS) play a vital role in meeting the growing demand for higher data rates and reliability in wireless systems. This study focuses on analyzing the performance of RIS systems to gain a deeper understanding of their potential.The paper presents a mathematical analysis of the RIS system,deriving closed-form formulae that express its characteristics including signal-to-noise ratio(SNR)distribution,ergodic and effective capacity,outage,and error probability. The obtained formulae are newly derived and unconditionally valid solutions. Numerical results demonstrate a close agreement between the derived formulae and MonteCarlo simulation outcomes.
基金This work was supported in part by National Natural Science Foundation of China(No.61771368)the Young Elite Scientists Sponsorship Program By CAST(2016QNRC001)Part of this work has been accepted by the IEEE International Symposium on Dynamic Spectrum Access Networks(DySPAN),。
文摘Spectrum and energy resources are very important for the rapidly developing of thefifth generation(5G)wireless communication networks.Cognitive radio and energy harvesting technologies,which focus on the spectrum efficiency and the energy efficiency,respectively,can be jointly used for solving the scarcities of spectrum and energy in energy harvesting cognitive radio networks(EHCRNs),where the energy is absorbed from ambient space and spectrum is licensed to the primary users.However,how to guarantee the quality of service(QoS)for EHCRNs is still a challenging problem.In this paper,we develop the optimal power and rate adaptation scheme under statistical QoS provisioning for EHCRNs.In particular,we analyze the power constraints of EHCRNs.Then,we formulate the effective capacity maximization problem for EHCRNs,solving which we obtain the closedform of the optimal power allocation and rate adaptation scheme under different power constraints.Numerical analyses verify the effective capacity enhancement and validate the relationships among the effective capacity,the QoS exponent,the energy arrival rate,and the average interference power.
基金Thanks for the financial support from The National Maize Industry Technology R&D CenterMechanized corn(CARS-02)production system optimization technology and equipment research demonstration projects(200903059).
文摘Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line may be altered according to the field conditions.Tractor drivers usually use an angle close to maximum in order to decrease the tillage depth,consequently decreasing power requirements,without considering the tillage quality and the impact on the soil properties.This experiment was conducted at the College of Agricultural Studies farm of Sudan University of Science and Technology to study the effects of three tilt angles(15°,20°and 25°)on soil bulk density,mean weight diameter,wheel slippage,work rate(or effective field capacity)and soil volume disturbed using mounted disk plough.The nature of soil on the farm found to be light clay.The theoretical forward speed was maintained at 6 km/h.The results showed that increasing tilt angle of the plough significantly(p<0.05)increased the bulk density,mean weight diameter and field capacity while significantly decreasing the tractor wheel slippage and soil volume disturbance.
