Sequential Latin hypercube designs(SLHDs) have recently received great attention for computer experiments, with much of the research restricted to invariant spaces. The related systematic construction methods are infl...Sequential Latin hypercube designs(SLHDs) have recently received great attention for computer experiments, with much of the research restricted to invariant spaces. The related systematic construction methods are inflexible, and algorithmic methods are ineffective for large designs. For designs in contracting spaces, systematic construction methods have not been investigated yet. This paper proposes a new method for constructing SLHDs via good lattice point sets in various experimental spaces. These designs are called sequential good lattice point(SGLP) sets. Moreover, we provide efficient approaches for identifying the(nearly)optimal SGLP sets under a given criterion. Combining the linear level permutation technique, we obtain a class of asymptotically optimal SLHDs in invariant spaces, where the L1-distance in each stage is either optimal or asymptotically optimal. Numerical results demonstrate that the SGLP set has a better space-filling property than the existing SLHDs in invariant spaces. It is also shown that SGLP sets have less computational complexity and more adaptability.展开更多
In a jamming environment with multiple wideband and narrowband jammers, global positioning system （GPS） receivers can use space-time processing to efficiently suppress the jamming. However, the computational complex...In a jamming environment with multiple wideband and narrowband jammers, global positioning system （GPS） receivers can use space-time processing to efficiently suppress the jamming. However, the computational complexity of space-time algorithms restricts their application in practical GPS receivers. This paper describes a reduced-rank multi-stage nested Wiener filter （MSNWF） based on subspace decomposition and Wiener filter （WF） to eliminate the effect of jamming in anti-jamming GPS receivers. A general sidelobe canceller （GSC） structure that is equivalent to the MSNWF is used to facilitate calculation of the optimal weights for the space-time processing. Simulation results demonstrate the satisfactory performance of the MSNWF to cancel jamming and the significant reduction in computational complexity by the reduced-rank processing. The technique offers a feasible space-time processing solution for anti-jamming GPS receivers.展开更多
针对分布式空间飞行器自组网使用传统时分多址(Time Division Multiple Access,TDMA)时隙分配方式时网络时延大、传输效率不高的问题,提出了一种基于双频通信的动态时分多址时隙分配(Dual Frequency Dynamic Time Division Multiple Acc...针对分布式空间飞行器自组网使用传统时分多址(Time Division Multiple Access,TDMA)时隙分配方式时网络时延大、传输效率不高的问题,提出了一种基于双频通信的动态时分多址时隙分配(Dual Frequency Dynamic Time Division Multiple Access,DF-DTDMA)方案。DF-DTDMA方案采用双频通信分别传输低速广播业务和高速定向业务,提高了网络吞吐量。在低频网络层提出了嵌套型时隙分配策略降低网络拓扑变化快带来的定向业务丢包率;在高频网络层提出了基于空间复用的定向无冲突时隙分配策略,避免发生信息碰撞,提高了网络的可靠性。仿真结果表明,相比传统TDMA协议,DF-DTDMA方案有效降低了飞行器网络丢包率,提升了网络吞吐量,具有高可靠性和灵活性。展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.11871288,12131001,and 12226343)National Ten Thousand Talents Program+2 种基金Fundamental Research Funds for the Central UniversitiesChina Scholarship CouncilU.S.National Science Foundation(Grant No.DMS18102925)。
文摘Sequential Latin hypercube designs(SLHDs) have recently received great attention for computer experiments, with much of the research restricted to invariant spaces. The related systematic construction methods are inflexible, and algorithmic methods are ineffective for large designs. For designs in contracting spaces, systematic construction methods have not been investigated yet. This paper proposes a new method for constructing SLHDs via good lattice point sets in various experimental spaces. These designs are called sequential good lattice point(SGLP) sets. Moreover, we provide efficient approaches for identifying the(nearly)optimal SGLP sets under a given criterion. Combining the linear level permutation technique, we obtain a class of asymptotically optimal SLHDs in invariant spaces, where the L1-distance in each stage is either optimal or asymptotically optimal. Numerical results demonstrate that the SGLP set has a better space-filling property than the existing SLHDs in invariant spaces. It is also shown that SGLP sets have less computational complexity and more adaptability.
文摘In a jamming environment with multiple wideband and narrowband jammers, global positioning system （GPS） receivers can use space-time processing to efficiently suppress the jamming. However, the computational complexity of space-time algorithms restricts their application in practical GPS receivers. This paper describes a reduced-rank multi-stage nested Wiener filter （MSNWF） based on subspace decomposition and Wiener filter （WF） to eliminate the effect of jamming in anti-jamming GPS receivers. A general sidelobe canceller （GSC） structure that is equivalent to the MSNWF is used to facilitate calculation of the optimal weights for the space-time processing. Simulation results demonstrate the satisfactory performance of the MSNWF to cancel jamming and the significant reduction in computational complexity by the reduced-rank processing. The technique offers a feasible space-time processing solution for anti-jamming GPS receivers.
文摘针对分布式空间飞行器自组网使用传统时分多址(Time Division Multiple Access,TDMA)时隙分配方式时网络时延大、传输效率不高的问题,提出了一种基于双频通信的动态时分多址时隙分配(Dual Frequency Dynamic Time Division Multiple Access,DF-DTDMA)方案。DF-DTDMA方案采用双频通信分别传输低速广播业务和高速定向业务,提高了网络吞吐量。在低频网络层提出了嵌套型时隙分配策略降低网络拓扑变化快带来的定向业务丢包率;在高频网络层提出了基于空间复用的定向无冲突时隙分配策略,避免发生信息碰撞,提高了网络的可靠性。仿真结果表明,相比传统TDMA协议,DF-DTDMA方案有效降低了飞行器网络丢包率,提升了网络吞吐量,具有高可靠性和灵活性。
