高速移动环境下OTSM迭代检测算法研究

正交时序复用( Orthogonal Time Sequency Multiplexing, OTSM)通过级联时分和沃尔什-哈达玛(WHT)复用将信息符号在时延和序列域进行复用。由于WHT在调制解调过程不需要进行复杂的乘法运算,相比于正交时频空(OTFS)调制有更低的调制复杂度。该文针对高速移动环境下的OTSM系统提出了一种二级均衡器：首先利用信道矩阵的稀疏性和带状结构在时域逐块进行低复杂度MMSE检测;随后采用高斯-赛德尔(GS)迭代检测进一步消除残余符号干扰。仿真结果表明,所提算法与基于单抽头频域均衡的GS迭代检测算法相比,采用16QAM调制且误码率为10^–4时有1.8 dB性能增益。     

基于迭代方法的补偿器系统设计

针对F数为4的高次非球面,设计了一套基于平行光束照射的高精度补偿器。系统工作波长为632.8 nm,设计残差为0.0018λ。提出了求解两片检测透镜组成补偿器初始结构的新方法。该方法合理假设补偿器部分结构参数,通过判断补偿器与非球面的Seidel系数之和最小获得未知参数。比较非球面在补偿器第一面位置处的高斯像高与假设的入射平行光高度,通过MATLAB迭代计算得到高度差小于预设误差,进而确定平行光入射高度。重新复算得到最终的初始结构。最后将迭代计算得到的各个面Seidel系数和ZEMAX给出的结果进行比较,证实了该方法的可靠性。     

A Gauss–Seidel type solver for the fast computation of input-constrained control systems

An important class of nonlinear control systems can be represented as the feedback interconnection of two parts: a linear time-invariant system and a block of decentralized nonlinearities. When the linear time-invariant part has a nontrivial feedthrough term or the nonlinearity has a feedback gain, control computation involves the online implementation of a multivariable algebraic loop which must be resolved at each sampling instant. The requirements for such online computation may result in several implementation issues, especially in real-time and embedded control applications. This paper considers the implementation of such algebraic loops arising from several input-constrained systems. The proposed solution algorithm is globally convergent for a very large class of feedthrough or feedback gains and shows promise for real-time and embedded control applications where a fast but approximate solution is of the essence.     

New gauss–seidel like block iterative methods to solve discrete boundary value problems

The concept of new Gauss–Seidel like iterative methods, which was introduced in [3], will be extended so as to obtain a class of convergent Gauss–Seidel like block iterative methods to solve linear matrix equations Ax=b with an M-Matrix A. New block iterative methods will be applied to finite difference approximations of the Laplace's equation on a square (“model problem” [8]) which surpass even the block successive overrelaxation iterative method with optimum relaxation factor in this example.     

基于全光引导的快速捕获指向控制技术研究

传统激光通信受到强电磁信号干扰时,导致电学引导机制失灵,初始指向将无法建立。为了解决强电磁干扰导致无法正常激光通信的问题,提出了一种结合伺服控制技术的全光捕获的控制技术。该方法对于全光引导光学模型进行解析研究,进而得出全光引导跟踪数学模型,在此基础上加入伺服控制技术,通过对高斯—赛德尔迭代算法的融合改进研究,以控制两个独立激光通信端机的快速捕获,精准指向与跟踪。实验结果表明,设计的捕获方案能进行全周90°/s的方位扫描,并55 s内完成俯仰20°的捕获。使激光通信在静默条件下快速建链有广阔的应用前景。     

Finite-element Discretization of Static Hamilton-Jacobi Equations based on a Local Variational Principle

We propose a linear finite-element discretization of Dirichlet problems for static Hamilton–Jacobi equations on unstructured triangulations. The discretization is based on simplified localized Dirichlet problems that are solved by a local variational principle. It generalizes several approaches known in the literature and allows for a simple and transparent convergence theory. In this paper the resulting system of nonlinear equations is solved by an adaptive Gauss–Seidel iteration that is easily implemented and quite effective as a couple of numerical experiments show.Dedicated to Peter Deuflhard on the occasion of his 60th birthday     

线性方程组迭代法在流处理器上的映射与分析

斯坦福大学的Imagine流处理器具有很强的计算能力,如何将该体系结构应用在科学计算领域是当前研究的热点。解线性方程组的迭代法在工程和科学计算的各个领域中有着十分广泛的应用,该算法具有较好的计算密集性和并行性,十分适合流处理器的计算模型。本文分别针对系数矩阵的规模大小和稠密程度,介绍了Jacobi和Seidel迭代在流处
理器上的映射。实验结果表明,迭代算法能高效地开发Imagine的计算能力,取得较高的性能加速。     

Exact performance analytical model for spectrum allocation in flexible grid optical networks

Dynamic flexible grid optical networks have gained much attention because of the advantages of high spectrum efficiency and flexibility, while the performance analysis will be more complex compared with fixed grid optical networks. An analytical Markov model is first presented in the paper, which can exactly describe the stochastic characteristics of the spectrum allocation in flexible grid optical networks considering both random-fit and first-fit resource assignment policies. We focus on the effect of spectrum contiguous constraint which has not been systematically studied in respect of mathematical modeling, and three major properties of the model are presented and analyzed. The model can expose key performance features and act as the foundation of modeling the Routing and Spectrum Assignment (RSA) problem with diverse topologies. Two heuristic algorithms are also proposed to make it more tractable. Finally, several key parameters, such as blocking probability, resource utilization rate and fragmentation rate are presented and computed, and the corresponding Monte Carlo simulation results match closely with analytical results, which prove the correctness of this mathematical model.