利用虚拟机的灵活性和快速部署能力,设计并实现了任务部署与调度系统(task deployment and dispatch system,TDDS).TDDS能够根据用户的需求,为用户的计算任务提供可以进行资源配置的集群计算环境,满足了用户对不同操作系统、不同应用程...利用虚拟机的灵活性和快速部署能力,设计并实现了任务部署与调度系统(task deployment and dispatch system,TDDS).TDDS能够根据用户的需求,为用户的计算任务提供可以进行资源配置的集群计算环境,满足了用户对不同操作系统、不同应用程序和不同计算资源的需求.TDDS还使用了负载均衡策略,以提高物理集群资源的利用率.提出了两种虚拟机部署策略,用以加快虚拟集群部署的速度.TDDS尽量控制虚拟机系统镜像的大小和访问频率,以提高部署的效率.实验表明,TDDS系统能够快速灵活地部署用户所需要的计算环境和计算资源,负载均衡的调度策略也切实提高了物理集群处理任务的能力,提高了集群的使用率.展开更多
TDD(Time Division Duplex) is one of the two duplex modes.TD-SCDMA(Time division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also...TDD(Time Division Duplex) is one of the two duplex modes.TD-SCDMA(Time division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology,also called as beamforming.As the long term evolution of TD-SCDMA,TDLTE(A)(Time Division-Lone Term Evolution,and TD-LTE Advanced) introduced OFDM(Orthogonal Frequency Division Multiplexing)and enhanced smart antenna technology together with MIMO(Multiple Input Multiple Output),which are adopted by LTE FDD(Frequency Division Duplex) either.It is indicated that TD-SCDMA and TD-LTE(A)have opened a sustainable utilization era of TDD and smart antenna Technologies in the wireless mobile communication.This paper aims to present a systematic introduction to TDD-based mobile communications from TD-SCDMA to TD-LTE and beyond and its comparisons to FDD,with particular focuses on TDD key technologies,principles of TDD cellular mobile systems,TDD evolution path,and future TDD 5G directions.We hope that this paper will provide a comprehensive overview of TDD technology upgrade and its standard evolution,and serve as a valuable reference for research on 5G mobile communication systems.It is believed that TDD will play more important role in 5G.展开更多
Owing to the dramatic mobile IP growth,the emerging Internet of Things,and cloud-based applications,wireless networking is witnessing a paradigm shift.By fully exploiting spatial degrees of freedom,massive multiple-in...Owing to the dramatic mobile IP growth,the emerging Internet of Things,and cloud-based applications,wireless networking is witnessing a paradigm shift.By fully exploiting spatial degrees of freedom,massive multiple-input-multiple-output(MIMO) systems promise significant gains in data rates and link reliability.Although the research community has recognized the theoretical benefits of these systems,building the hardware of such complex systems is a challenge in practice.This paper presents a time division duplex(TDD)-based 128-antenna massive MIMO prototype system from theory to reality.First,an analytical signal model is provided to facilitate the setup of a feasible massive MIMO prototype system.Second,a link-level simulation consistent with practical TDDbased massive MIMO systems is conducted to guide and validate the massive MIMO system design.We design and implement the TDDbased 128-antenna massive MIMO prototype system with the guidelines obtained from the link-level simulation.Uplink real-time video transmission and downlink data transmission under the configuration of multiple single-antenna users are achieved.Comparisons withstate-of-the-art prototypes demonstrate the advantages of the proposed system in terms of antenna number,bandwidth,latency,and throughput.The proposed system is also equipped with scalability,which makes the system applicable to a wide range of massive scenarios.展开更多
Coordinated multi-point transmission/reception, CoMP, technique converts the interference signal into the useful information by controlling the interfering signals among adjacent cells. Theoretically, it is a breakthr...Coordinated multi-point transmission/reception, CoMP, technique converts the interference signal into the useful information by controlling the interfering signals among adjacent cells. Theoretically, it is a breakthrough from the traditional interference limited non-cooperative single point transmission system, improving link reliability and enhancing the data rate. CoMP is regarded as one of the most essential and effective techniques in eliminating the inter-cell interference, boosting cell edge throughput and overall system throughput. CoMP technique has obvious advantages in TDD(time division duplexing) cellular mobile system; the necessary channel state information for CoMP can be easily obtained through channel reciprocity property in TDD system. CoMP scheme in TDD system and likely problems are analyzed in this paper, and it is shown by system simulations that the significant gain can be achieved.展开更多
Objective:We evaluated the efficacy and safety of transdermal preparations of Sinomenium acutum(SA)for rheumatoid arthritis(RA).Methods:Randomized controlled trials(RCTs)of SA transdermal preparations for RA were extr...Objective:We evaluated the efficacy and safety of transdermal preparations of Sinomenium acutum(SA)for rheumatoid arthritis(RA).Methods:Randomized controlled trials(RCTs)of SA transdermal preparations for RA were extracted from relevant databases and screened in accordance with the inclusion criteria.The Cochrane System Evaluation Manual(version 5.1.0)was used to assess the quality of the included trials.We used the Cochrane Review Manager(version 5.4)to conduct the meta-analysis.Results:Six trials comprising 436 patients(220 patients in the treatment group and 216 patients in the control group)were analyzed.The meta-analysis indicated that SA transdermal preparations in combination with disease-modifying antirheumatic drugs(DMARDs)enhanced the overall effect(odds ratio[OR]3.97,95%confidence interval[CI][2.25,7.00],P<0.00001),decreased visual analogue scale(VAS)results(mean difference[MD]-0.64,95%CI[-1.20,-0.09],P=0.02),decreased laboratory indexes including the erythrocyte sedimentation rate(ESR)(MD-4.36,95%CI[-5.63,-3.08],P<0.00001)and C-reactive protein(CRP)(MD-3.6,95%CI[-3.99,-3.21,P<0.00001]),and decreased the Disease Activity Score-28(DAS28)(MD-0.41,95%CI[-0.78,-0.03],P=0.03).The results suggest that combination therapy did not shorten the duration of morning stiffness(DMS;standardized MD[SMD]-6.13,95%CI[-17.33,5.06],P=0.28)or reduce rheumatoid factor(RF)laboratory indexes(SMD-0.85;95%CI[-2.19,0.49],P=0.21).Only one study reported adverse reactions,and thus,it was difficult to determine whether adverse drug reactions in the combination therapy group were significantly different from those in the control group.Conclusion:We found that SA transdermal preparations combined with DMARDs may have greater clinical efficacy than DMARDs for RA.More well-designed and high-quality RCTs are required to verify the findings and determine whether transder-mal preparations cause fewer adverse events.展开更多
Current uplink power control algorithm of code division multiple access （CDMA） time division duplex（TDD） system contains signal-to-interference-ratio（SIR） and interference measurement, which is based on history ...Current uplink power control algorithm of code division multiple access （CDMA） time division duplex（TDD） system contains signal-to-interference-ratio（SIR） and interference measurement, which is based on history information. However, the adjustment of transmission power of one user equipment（UE） will affect SIR of the others, because the power control is done independently of the power adjustment of other UE＇s. So the convergence speed of power control is not fast and the system performance degrades. In the proposed algorithm, all UE＇s assigned in same time slot adjust their transmission power based on current information, which takes into account the adjustments of transmission power of all UE＇s. The simulation results indicated that the proposed algorithm outperforms the old algorithm.展开更多
In this paper, a theoretical analysis of Time Division Duplex-Code Division Multiple Access (TDD-CDMA) uplink capacity constraint is presented when employing the smart antenna techniques. The evaluation formulations o...In this paper, a theoretical analysis of Time Division Duplex-Code Division Multiple Access (TDD-CDMA) uplink capacity constraint is presented when employing the smart antenna techniques. The evaluation formulations of capacity and load for multi-services are proposed. In order to maximize the throughput, the objective of optimization is proposed, and an advanced uplink resource management algo-rithm is developed. The proposed algorithm based on the least interference admission control scheme focuses on the maximum throughput for the circuit switched multi-services. The simulation results show that the pro-posed strategy has a significant improvement in throughput when the optimum admission control threshold is set.展开更多
An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A ...An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against link gain changes, and outperforms the reference algorithms.展开更多
Recently, the mobile communication industry is moving rapidly towards long-term evolution (LTE) systems. LTE aims to provide improved service quality over 3G systems in terms of throughput, spectral efficiency, latenc...Recently, the mobile communication industry is moving rapidly towards long-term evolution (LTE) systems. LTE aims to provide improved service quality over 3G systems in terms of throughput, spectral efficiency, latency, and peak data rate, and MIMO technique is one of the key enablers of the LTE system for achieving these diverse goals. Among several operational modes of MIMO, multiuser MIMO (MU-MIMO) in which the base station transmits multiple streams to multiple users, has received much attention as a way for achieving improvement in performance. In this paper we present a Multiuser MIMO-OFDM-based simulator that includes the main physical layer functionalities and calculate the throughput of LTE Frequency Division Duplex (FDD) and Time Division Duplex (TDD) systems. The simulator has been used to evaluate the performance of the 3GPP Long-Term Evolution (LTE) technology.展开更多
The FuTURE 4G Time Division Duplex (TDD) trial system uses 3.5 GHz carrier frequency and several crucial technologies including broadband Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multipl...The FuTURE 4G Time Division Duplex (TDD) trial system uses 3.5 GHz carrier frequency and several crucial technologies including broadband Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM). These technologies challenge the link budget and networking analysis of the FuTURE 4G TDD trial network. This paper analyzes the practical 3.5 GHz propagation model and the link budget of Radio Frequency (RF) parameters of the trial system. Moreover,it introduces networking analysis and network planning of the trial system,which combines the field test results of the MIMO system. The FuTURE 4G TDD trial system and its trial network have been accomplished with successful checkup. The trial system fulfills all the requirements with two Access Points (AP) and three Mobile Terminals (MT),which supports multi-user,mobility,a high peak rate of 100 Mb/s,High-Definition TV (HDTV),high-speed data download,and Voice over IP (VoIP) services.展开更多
This paper addresses the problem of channel estimation in a multiuser multi-cell wireless communications system in which the base station(BS)is equipped with a very large number of antennas(also referred to as"ma...This paper addresses the problem of channel estimation in a multiuser multi-cell wireless communications system in which the base station(BS)is equipped with a very large number of antennas(also referred to as"massive multiple-input multiple-output(MIMO)").We consider a time-division duplexing(TDD)scheme,in which reciprocity between the uplink and downlink channels can be assumed.Channel estimation is essential for downlink beamforming in massive MIMO,nevertheless,the pilot contamination effect hinders accurate channel estimation,which leads to overall performance degradation.Benefitted from the asymptotic orthogonality between signal and interference subspaces for non-overlapping angle-of arrivals(AOAs)in the large-scale antenna system,we propose a multiple signals classification(MUSIC)based channel estimation algorithm during the uplink transmission.Analytical and numerical results verify complete pilot decontamination and the effectiveness of the proposed channel estimation algorithm in the multiuser multi-cell massive MIMO system.展开更多
文摘利用虚拟机的灵活性和快速部署能力,设计并实现了任务部署与调度系统(task deployment and dispatch system,TDDS).TDDS能够根据用户的需求,为用户的计算任务提供可以进行资源配置的集群计算环境,满足了用户对不同操作系统、不同应用程序和不同计算资源的需求.TDDS还使用了负载均衡策略,以提高物理集群资源的利用率.提出了两种虚拟机部署策略,用以加快虚拟集群部署的速度.TDDS尽量控制虚拟机系统镜像的大小和访问频率,以提高部署的效率.实验表明,TDDS系统能够快速灵活地部署用户所需要的计算环境和计算资源,负载均衡的调度策略也切实提高了物理集群处理任务的能力,提高了集群的使用率.
基金supported in part by the National Natural Science Foundation of China for Distinguished Young Scholar,Grant Number:61425012
文摘TDD(Time Division Duplex) is one of the two duplex modes.TD-SCDMA(Time division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology,also called as beamforming.As the long term evolution of TD-SCDMA,TDLTE(A)(Time Division-Lone Term Evolution,and TD-LTE Advanced) introduced OFDM(Orthogonal Frequency Division Multiplexing)and enhanced smart antenna technology together with MIMO(Multiple Input Multiple Output),which are adopted by LTE FDD(Frequency Division Duplex) either.It is indicated that TD-SCDMA and TD-LTE(A)have opened a sustainable utilization era of TDD and smart antenna Technologies in the wireless mobile communication.This paper aims to present a systematic introduction to TDD-based mobile communications from TD-SCDMA to TD-LTE and beyond and its comparisons to FDD,with particular focuses on TDD key technologies,principles of TDD cellular mobile systems,TDD evolution path,and future TDD 5G directions.We hope that this paper will provide a comprehensive overview of TDD technology upgrade and its standard evolution,and serve as a valuable reference for research on 5G mobile communication systems.It is believed that TDD will play more important role in 5G.
基金supported in part by the National Science Foundation(NSFC) for Distinguished Young Scholars of China with Grant 61625106the National Natural Science Foundation of China under Grant 61531011the Hong Kong,Macao and Taiwan Science and Technology Cooperation Program of China(2016YFE0123100)
文摘Owing to the dramatic mobile IP growth,the emerging Internet of Things,and cloud-based applications,wireless networking is witnessing a paradigm shift.By fully exploiting spatial degrees of freedom,massive multiple-input-multiple-output(MIMO) systems promise significant gains in data rates and link reliability.Although the research community has recognized the theoretical benefits of these systems,building the hardware of such complex systems is a challenge in practice.This paper presents a time division duplex(TDD)-based 128-antenna massive MIMO prototype system from theory to reality.First,an analytical signal model is provided to facilitate the setup of a feasible massive MIMO prototype system.Second,a link-level simulation consistent with practical TDDbased massive MIMO systems is conducted to guide and validate the massive MIMO system design.We design and implement the TDDbased 128-antenna massive MIMO prototype system with the guidelines obtained from the link-level simulation.Uplink real-time video transmission and downlink data transmission under the configuration of multiple single-antenna users are achieved.Comparisons withstate-of-the-art prototypes demonstrate the advantages of the proposed system in terms of antenna number,bandwidth,latency,and throughput.The proposed system is also equipped with scalability,which makes the system applicable to a wide range of massive scenarios.
文摘Coordinated multi-point transmission/reception, CoMP, technique converts the interference signal into the useful information by controlling the interfering signals among adjacent cells. Theoretically, it is a breakthrough from the traditional interference limited non-cooperative single point transmission system, improving link reliability and enhancing the data rate. CoMP is regarded as one of the most essential and effective techniques in eliminating the inter-cell interference, boosting cell edge throughput and overall system throughput. CoMP technique has obvious advantages in TDD(time division duplexing) cellular mobile system; the necessary channel state information for CoMP can be easily obtained through channel reciprocity property in TDD system. CoMP scheme in TDD system and likely problems are analyzed in this paper, and it is shown by system simulations that the significant gain can be achieved.
基金The study was financed by the Financing Scheme of Arising Interdisciplinary Subject of TCM in Shanghai,China(No.Shxxjcxk201709)the TCM Genre Program of Shanghai Health Bureau of China(No.ZY(2018-2020)-CCCX1006)the Shanghai Sports Bureau Project of China(Nos.20J020 and 21J013).
文摘Objective:We evaluated the efficacy and safety of transdermal preparations of Sinomenium acutum(SA)for rheumatoid arthritis(RA).Methods:Randomized controlled trials(RCTs)of SA transdermal preparations for RA were extracted from relevant databases and screened in accordance with the inclusion criteria.The Cochrane System Evaluation Manual(version 5.1.0)was used to assess the quality of the included trials.We used the Cochrane Review Manager(version 5.4)to conduct the meta-analysis.Results:Six trials comprising 436 patients(220 patients in the treatment group and 216 patients in the control group)were analyzed.The meta-analysis indicated that SA transdermal preparations in combination with disease-modifying antirheumatic drugs(DMARDs)enhanced the overall effect(odds ratio[OR]3.97,95%confidence interval[CI][2.25,7.00],P<0.00001),decreased visual analogue scale(VAS)results(mean difference[MD]-0.64,95%CI[-1.20,-0.09],P=0.02),decreased laboratory indexes including the erythrocyte sedimentation rate(ESR)(MD-4.36,95%CI[-5.63,-3.08],P<0.00001)and C-reactive protein(CRP)(MD-3.6,95%CI[-3.99,-3.21,P<0.00001]),and decreased the Disease Activity Score-28(DAS28)(MD-0.41,95%CI[-0.78,-0.03],P=0.03).The results suggest that combination therapy did not shorten the duration of morning stiffness(DMS;standardized MD[SMD]-6.13,95%CI[-17.33,5.06],P=0.28)or reduce rheumatoid factor(RF)laboratory indexes(SMD-0.85;95%CI[-2.19,0.49],P=0.21).Only one study reported adverse reactions,and thus,it was difficult to determine whether adverse drug reactions in the combination therapy group were significantly different from those in the control group.Conclusion:We found that SA transdermal preparations combined with DMARDs may have greater clinical efficacy than DMARDs for RA.More well-designed and high-quality RCTs are required to verify the findings and determine whether transder-mal preparations cause fewer adverse events.
基金Supported by Project of Philips Research (2000-109)
文摘Current uplink power control algorithm of code division multiple access （CDMA） time division duplex（TDD） system contains signal-to-interference-ratio（SIR） and interference measurement, which is based on history information. However, the adjustment of transmission power of one user equipment（UE） will affect SIR of the others, because the power control is done independently of the power adjustment of other UE＇s. So the convergence speed of power control is not fast and the system performance degrades. In the proposed algorithm, all UE＇s assigned in same time slot adjust their transmission power based on current information, which takes into account the adjustments of transmission power of all UE＇s. The simulation results indicated that the proposed algorithm outperforms the old algorithm.
基金Sponsored by the National Advanced Technologies Researching and Developing Programs (No.2004AA123160).
文摘In this paper, a theoretical analysis of Time Division Duplex-Code Division Multiple Access (TDD-CDMA) uplink capacity constraint is presented when employing the smart antenna techniques. The evaluation formulations of capacity and load for multi-services are proposed. In order to maximize the throughput, the objective of optimization is proposed, and an advanced uplink resource management algo-rithm is developed. The proposed algorithm based on the least interference admission control scheme focuses on the maximum throughput for the circuit switched multi-services. The simulation results show that the pro-posed strategy has a significant improvement in throughput when the optimum admission control threshold is set.
基金Project supported by the National Science Foundation for Creative Research Groups （Grant No.60521002）, and the National Key Technologies R＆D Program （Grant No.2005BA908B02）
文摘An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against link gain changes, and outperforms the reference algorithms.
文摘Recently, the mobile communication industry is moving rapidly towards long-term evolution (LTE) systems. LTE aims to provide improved service quality over 3G systems in terms of throughput, spectral efficiency, latency, and peak data rate, and MIMO technique is one of the key enablers of the LTE system for achieving these diverse goals. Among several operational modes of MIMO, multiuser MIMO (MU-MIMO) in which the base station transmits multiple streams to multiple users, has received much attention as a way for achieving improvement in performance. In this paper we present a Multiuser MIMO-OFDM-based simulator that includes the main physical layer functionalities and calculate the throughput of LTE Frequency Division Duplex (FDD) and Time Division Duplex (TDD) systems. The simulator has been used to evaluate the performance of the 3GPP Long-Term Evolution (LTE) technology.
基金the National Natural Science Foundation of China under Grant 60496312the 863 Program of China under Grants 2003AA12331004 and 2006AA01Z260.
文摘The FuTURE 4G Time Division Duplex (TDD) trial system uses 3.5 GHz carrier frequency and several crucial technologies including broadband Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM). These technologies challenge the link budget and networking analysis of the FuTURE 4G TDD trial network. This paper analyzes the practical 3.5 GHz propagation model and the link budget of Radio Frequency (RF) parameters of the trial system. Moreover,it introduces networking analysis and network planning of the trial system,which combines the field test results of the MIMO system. The FuTURE 4G TDD trial system and its trial network have been accomplished with successful checkup. The trial system fulfills all the requirements with two Access Points (AP) and three Mobile Terminals (MT),which supports multi-user,mobility,a high peak rate of 100 Mb/s,High-Definition TV (HDTV),high-speed data download,and Voice over IP (VoIP) services.
文摘This paper addresses the problem of channel estimation in a multiuser multi-cell wireless communications system in which the base station(BS)is equipped with a very large number of antennas(also referred to as"massive multiple-input multiple-output(MIMO)").We consider a time-division duplexing(TDD)scheme,in which reciprocity between the uplink and downlink channels can be assumed.Channel estimation is essential for downlink beamforming in massive MIMO,nevertheless,the pilot contamination effect hinders accurate channel estimation,which leads to overall performance degradation.Benefitted from the asymptotic orthogonality between signal and interference subspaces for non-overlapping angle-of arrivals(AOAs)in the large-scale antenna system,we propose a multiple signals classification(MUSIC)based channel estimation algorithm during the uplink transmission.Analytical and numerical results verify complete pilot decontamination and the effectiveness of the proposed channel estimation algorithm in the multiuser multi-cell massive MIMO system.
