Long Term Evolution (LTE) Carrier Aggregation (CA) was introduced by the Release-10 3GPP specifications. CA allows aggregation of up to 5 cells for a terminal;both downlink (DL) CA and uplink (UL) CA are supported by ...Long Term Evolution (LTE) Carrier Aggregation (CA) was introduced by the Release-10 3GPP specifications. CA allows aggregation of up to 5 cells for a terminal;both downlink (DL) CA and uplink (UL) CA are supported by the 3GPP specifications. However, the first commercial deployments focus on the aggregation of two cells in the downlink. The benefits of LTE CA are increased terminal peak data rates, aggregation of fragmented spectrum and fast load balancing. In this paper, we analyze different strategies of DL scheduling for LTE CA including centralized, independent and distributed schedulers, we provide the corresponding simulation results considering UE data rate limitations and different traffic models. Also, we compare the performance of a single LTE carrier with LTE CA using the same total bandwidth.展开更多
The orthogonal frequency division multiplexing（OFDM） is currently used in long term evolution（LTE） system. The time offset estimation（TOE） and frequency offset estimation（FOE） of OFDM is essential in mobile co...The orthogonal frequency division multiplexing（OFDM） is currently used in long term evolution（LTE） system. The time offset estimation（TOE） and frequency offset estimation（FOE） of OFDM is essential in mobile communication base. According to the conventional cross correlation TOE and FOE algorithms, a new cross correlation computation was proposed to estimate the time offset and frequency offset for LTE uplink system, so that the time offset and frequency offset can be estimated simultaneously with low complexity. Compared with the conventional TOE and FOE algorithms, the simulation show that the proposed can reduce complexity and improve performance for FOE with good performance for TOE in additive white Gaussian noise（AWGN） and multipath channel.展开更多
Orthogonal frequency division multiplexing （OFDM） is one of the key techniques for long term evolution （LTE） system. Frequency offset estimation of OFDM is an essential issue. Especially in the high-speed environm...Orthogonal frequency division multiplexing （OFDM） is one of the key techniques for long term evolution （LTE） system. Frequency offset estimation of OFDM is an essential issue. Especially in the high-speed environment, the frequency offset will become large. Based on the features of LTE uplink physical random access channel （PRACH）, this paper proposes a new frequency offset algorithm by using peak power ratio to enlarge the range of frequency offset estimation. According to the relation between frequency offset and the power delay profile （PDP）, the ratio of the peak power of the PDP at the main window to that at the negative window or positive window is utilized to estimate frequency offset. Simulation results show that the new proposed algorithm extends the estimation range of frequency offset from 1 000 Hz to 1 250 Hz. Meanwhile the accuracy of frequency offset estimation is almost not lost. Particularly in low signal noise ratio （SNR）, the new algorithm has lower mean square error （MSE） compared with traditional phase differential algorithm.展开更多
The effect of MnO4- and silver content on electrochemical behaviour of five commercial Pb-Ag alloy anodes was studied in acid zinc sulphate electrolyte with and without MnO4- ions at 38 °C during potential decay ...The effect of MnO4- and silver content on electrochemical behaviour of five commercial Pb-Ag alloy anodes was studied in acid zinc sulphate electrolyte with and without MnO4- ions at 38 °C during potential decay periods. When the anodes were immersed into acid zinc sulphate electrolyte without MnO4- ions, the Pb-0.72%Ag anode entered complete passivation state in the shortest time among the five anodes, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by measurement of open circuit potential. During immersion of the anodes, MnO4 ions accelerated the passivation and increased the corrosion current density of the anodes. After immersion in zinc electrolyte with MnO4-, the anode Pb-0.72%Ag had the best corrosion resistance, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, then the close anodes Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by the electrochemical impedance spectroscopy （EIS） analysis.展开更多
The aim of this paper is to set up an efficient nonlinear application algorithm predictive model for a multi aircraft landing dynamic system called “Aircraft Landing Dynamic System, Release 2019<em>A</em>...The aim of this paper is to set up an efficient nonlinear application algorithm predictive model for a multi aircraft landing dynamic system called “Aircraft Landing Dynamic System, Release 2019<em>A</em><sup>+</sup> version “<em>AIRLADYS R</em>2019<em>A</em><sup>+</sup>”. This programming software combines dynamic programming technic for mathematical computing and optimisation run under AMPL and KNITRO Solver. It uses also a descriptive programming technic for software design. The user interfaces designed in Glade are saved as XML, and by using the GtkBuilder GTK+ object these can be loaded by applications dynamically as needed. By using GtkBuilder, Glade XML files can be used in numerous programming languages including C, C++, C#, Java, Perl, Python, AMPL, etc. Glade is Free Software released under the GNU GPL License. By these tools, the solved problem is a mathematical modelization problem as a non-convex optimal control governed by ordinary non-linear differential equations. The dynamic programming technic is applied because it is a sufficiently high order and it does not require computation of the partial derivatives of the aircraft dynamic. This application will be coded with Linux system on 64 bit operating system, but it can also be run on the windows system. High running performances are obtained with results giving feasible trajectories with a robust optimizing of the objective function.展开更多
文摘Long Term Evolution (LTE) Carrier Aggregation (CA) was introduced by the Release-10 3GPP specifications. CA allows aggregation of up to 5 cells for a terminal;both downlink (DL) CA and uplink (UL) CA are supported by the 3GPP specifications. However, the first commercial deployments focus on the aggregation of two cells in the downlink. The benefits of LTE CA are increased terminal peak data rates, aggregation of fragmented spectrum and fast load balancing. In this paper, we analyze different strategies of DL scheduling for LTE CA including centralized, independent and distributed schedulers, we provide the corresponding simulation results considering UE data rate limitations and different traffic models. Also, we compare the performance of a single LTE carrier with LTE CA using the same total bandwidth.
基金supported by the National Natural Science Foundation of China (60572117)the Scientific Research Foundation for the returned Overseas Chinese scholars, State Education Ministry
文摘The orthogonal frequency division multiplexing（OFDM） is currently used in long term evolution（LTE） system. The time offset estimation（TOE） and frequency offset estimation（FOE） of OFDM is essential in mobile communication base. According to the conventional cross correlation TOE and FOE algorithms, a new cross correlation computation was proposed to estimate the time offset and frequency offset for LTE uplink system, so that the time offset and frequency offset can be estimated simultaneously with low complexity. Compared with the conventional TOE and FOE algorithms, the simulation show that the proposed can reduce complexity and improve performance for FOE with good performance for TOE in additive white Gaussian noise（AWGN） and multipath channel.
基金supported by the National Natural Science Foundation of China (60572117)the Scientific Research Foundation for the returned Overseas Chinese scholars, State Education Ministry.
文摘Orthogonal frequency division multiplexing （OFDM） is one of the key techniques for long term evolution （LTE） system. Frequency offset estimation of OFDM is an essential issue. Especially in the high-speed environment, the frequency offset will become large. Based on the features of LTE uplink physical random access channel （PRACH）, this paper proposes a new frequency offset algorithm by using peak power ratio to enlarge the range of frequency offset estimation. According to the relation between frequency offset and the power delay profile （PDP）, the ratio of the peak power of the PDP at the main window to that at the negative window or positive window is utilized to estimate frequency offset. Simulation results show that the new proposed algorithm extends the estimation range of frequency offset from 1 000 Hz to 1 250 Hz. Meanwhile the accuracy of frequency offset estimation is almost not lost. Particularly in low signal noise ratio （SNR）, the new algorithm has lower mean square error （MSE） compared with traditional phase differential algorithm.
基金Project(RDCPJ346365-06)supported by the Natural Sciences and Engineering Research Council of CanadaProject(51208193)supported by the National Natural Science Foundation of ChinaProject(11jj6034)supported by the Hunan Provincial Natural Science Foundation
文摘The effect of MnO4- and silver content on electrochemical behaviour of five commercial Pb-Ag alloy anodes was studied in acid zinc sulphate electrolyte with and without MnO4- ions at 38 °C during potential decay periods. When the anodes were immersed into acid zinc sulphate electrolyte without MnO4- ions, the Pb-0.72%Ag anode entered complete passivation state in the shortest time among the five anodes, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by measurement of open circuit potential. During immersion of the anodes, MnO4 ions accelerated the passivation and increased the corrosion current density of the anodes. After immersion in zinc electrolyte with MnO4-, the anode Pb-0.72%Ag had the best corrosion resistance, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, then the close anodes Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by the electrochemical impedance spectroscopy （EIS） analysis.
文摘The aim of this paper is to set up an efficient nonlinear application algorithm predictive model for a multi aircraft landing dynamic system called “Aircraft Landing Dynamic System, Release 2019<em>A</em><sup>+</sup> version “<em>AIRLADYS R</em>2019<em>A</em><sup>+</sup>”. This programming software combines dynamic programming technic for mathematical computing and optimisation run under AMPL and KNITRO Solver. It uses also a descriptive programming technic for software design. The user interfaces designed in Glade are saved as XML, and by using the GtkBuilder GTK+ object these can be loaded by applications dynamically as needed. By using GtkBuilder, Glade XML files can be used in numerous programming languages including C, C++, C#, Java, Perl, Python, AMPL, etc. Glade is Free Software released under the GNU GPL License. By these tools, the solved problem is a mathematical modelization problem as a non-convex optimal control governed by ordinary non-linear differential equations. The dynamic programming technic is applied because it is a sufficiently high order and it does not require computation of the partial derivatives of the aircraft dynamic. This application will be coded with Linux system on 64 bit operating system, but it can also be run on the windows system. High running performances are obtained with results giving feasible trajectories with a robust optimizing of the objective function.
