波长交换光网络中路由波长分配技术

路由波长分配问题是在给定连接的情况下,为该请求分配适当的光路进行传输。在无波长转换能力的情况下,需要为光路在其传输的链路上分配相同的波长,这就是波长连续性问题。物理层的光损伤极大的限制了光网络的能力,因此需要可感知损伤的路由波长分配算法来保证传输的质量。对于不同的感知损伤的路由波长分配方式,相应地,有不同的控制平面结构。     

损伤感知的光网络连接指配的关键问题研究

在透明网络中,光信号由于受到物理损伤的影响而质量降低,这使得损伤感知的连接指配日益成为人们研究的热点.文章从架构、损伤模型和损伤感知的路由波长分配(IRWA)算法3方面研究了损伤感知的光网络连接指配的     

WDM光网络的光路传输质量估计算法

在波长路由WDM光网中,信号在路由与波长分配算法(RWA)选定的光路上传输．传输过程中引入的各种串扰和噪声使信号的传输质量受到损伤,信号质量不断下降,目的结点无法正确有效地接收光信号。通过定义合理的结点和传输链路模型．提出了一种考虑线性传输损伤的比特错误率估算方法．在光路建立之前预先估计WDM网络中将要建立光路的传输质量,以此作为网络优化设计过程中RWA算法选路的依据。通过网络仿真和实验验证了算法的正确性。     

波长路由网络选路时的光信号质量限制研究

光网络中,路由与波长分配(RWA)算法是最优化网络性能的核心问题之一,传统的RWA算法都假设光网络的物理层状态是理想的,即不存在光信号传输损伤的问题.通过对这个缺陷的分析,将光信号的传输损伤问题充分考虑到路由与波长分配算法中,从算法的角度来实现对光信号的传输保护,这样做不仅能有效防止业务的物理损伤阻塞,还能极大地提高光网络的性能.     

光网络中支持区分业务的损伤感知QoS机制

光网络中物理层损伤会造成明显的信号质量下降。为了保证QoS(服务质量),必须在RWA(路由和波长分配)算法中考虑这些损伤及其引起的变化。文章提出了一种损伤感知的差异化路由与波长算法,并针对规则Mesh网络与Cernet网络进行了数值仿真,结果表明,在满足QoS要求的情况下优先保证网络中高等级业务的波长分配,能降低高等级业务的阻塞率,并能提高网络总体的资源利用率。     

全光网络中感知信号损伤的RWA算法

在全光网络中，信号沿着光通路在非理想介质中传输时，会引起质量恶化。当达到一定程度时。该光通路不可用。物理层的传输损伤引起连接阻塞。为了提供高质量的连接，路由和波长分配算法需要考虑信号质量。光信噪比和极化模式色散被认为是主要的限制因素。有两种感知损伤的RWA算法：最优路径算法，最先符合算法。     

WDM网络中基于分层图模型的ICBR路由算法

考虑到物理损伤导致光信号质量下降的严重性,提出了一种新的损伤感知路由和波长分配算法。该算法同时考虑多种线性和非线性损伤,从光信噪比(OSNR,Optical Signal Noise Ratio)和Q因子两方面来评估光信号的整体质量,严格保证了业务的服务质量。最后将损伤感知路由算法(ICBR,Impairment Constraint Based Routing algorithm)和分层图模型相结合,与传统ICBR算法相比,避免了不必要的连接阻塞,显著改善了网络性能。     

ASON中基于传输损伤的RWA算法研究

路由和波长分配(RWA)算法是ASON中的一个关键问题.由于信号传输过程中存在传输损伤,这将会影响到不同连接请求的公平性.对现有算法进行研究,提出了一种改进算法,在保证公平性的同时,尽量降低网络的阻塞率.仿真表明该算法能有效的降低阻塞,提高资源利用率.     

基于物理损伤联合影响的光信号脉宽模型研究

针对物理损伤的精确评估问题,分析了自相位调制(SPM)对群速度色散(GVD)的抑制或加强作用.基于它们共同对信号产生的影响,提出了考虑物理损伤联合影响的光信号脉宽模型,并将此模型应用到基于物理损伤感知的路由波长分配(IA-RWA)算法仿真中.仿真结果表明,综合考虑物理损伤的联合影响有利于准确规避损伤严重的路径,降低阻塞率.     

光网络中一种考虑信号损伤限制和服务质量区分的动态RWA算法

在光网络中,光信号沿着路由与波长分配(RWA)算法选定的光通路传输的过程中会受到各种信号损伤的影响而导致信号质量的不断下降,严重影响着业务的服务质量(QoS).而光网络中多样化的客户层业务往往有着不同的QoS的需求,因此有必要根据不同的业务QoS需求对光信号损伤的影响进行不同程度的控制.针对这一问题,提出了一种能同时考虑信号损伤限制和服务质量区分的动态RWA算法,并通过计算机仿真的方法对其性能进行了分析和验证.结果表明:该算法既能克服光网络中信号损伤的影响又能为不同级别的业务提供不同的QoS保证,更贴近实际需求.     

雷达视频压缩传输系统

深入研究了基于二维小波变换的雷达视频压缩算法，并将该算法运用到雷达视频传输系统的研制，在窄带设备上高质量传输雷达一次视频信号。     

Provisioning of dynamic traffic in mixed-line-rate optical networks with launch power determination

In mixed-line-rate (MLR) networks, different line rates on different wavelengths can coexist on the same fiber. MLR architectures can be built over transparent optical networks, where the transmitted signals remain in the optical domain along the entire path. Along the transparent optical path, a signal experiences various physical layer impairments (PLIs), and its quality degrades as it travels through each optical component. One of the major factors that affect the transmission quality is the launch power of the optical signal. The power must be large enough to ensure noise resiliency at the receiver, but it must be below the limit where fiber nonlinearities distort the signal. Moreover, high launch power is disruptive not only for the actual lightpath itself but also for neighboring lightpaths, and this effect is particularly critical in MLR networks since advanced modulation techniques used for high line rates are highly susceptible to PLIs. In this study, we investigate the problem of determining the appropriate launch power for provisioning of dynamic connection requests in MLR networks. By setting the appropriate launch power for each connection, we aim to maximize the number of established connections. We propose two different heuristics to determine the appropriate launch power of a lightpath. Worst-case best-case average (WBA) is based on optical reach of signal in a transparent optical network. In impairment-aware launch power determination (I-ALPD), current state of the network and impairments are evaluated to determine the launch power. The proposed approaches are practical and can adapt to the needs of network operators. Simulation results show that the performances of the proposed approaches show better results than the existing schemes in terms of blocking probability and bandwidth blocking ratio.     

WDM光网络中基于传输损伤的公平RWA算法

在WDM光网络中,物理层上存在使信号传输质量恶化的因素,当信号质量劣化到一定程度会导致连接失败,因此有必要在选路和波长分配RWA（Routing and Wavelength Assignment）算法中考虑物理层的传输损伤。连接公平性问题是指网络中长路径连接请求的阻塞率表现比短路径差,文中分析传输损伤约束的引入对连接公平性的影响,提出基于传输损伤的动态RWA算法：固定波长配额FWQ（Fixed Wavelength Quota）算法和非固定波长配额UFWQ（UnFixed Wavelength Quota）算法。     

Performance enhancement for impairment-aware SRLG failure protection in wavelength-routed optical networks

With the increase of size and number of shared risk link groups (SRLGs) in WDM networks, path protection tends to have longer working paths and backup paths due to SRLG-disjoint constraints, which makes physical impairment a major concern in working path and backup path provisioning, particularly in large-sized all optical networks. As a simple and efficient algorithm, the working path first algorithm is often used for path protection against SRLG failures, where the working path is calculated first by using the shortest-path algorithm on the graph, followed by using the SRLG-disjoint shortest path as backup path. Compared with the working path, the backup path calculated after the working path in the working path first algorithm is more vulnerable to physical impairment, since it may be much longer than the working path. As a result, if we reject those connections that cannot meet the physical impairment requirement, with SRLGs the blocking probability of path protection will be much higher. We argue that impairment must be taken into account together with capacity efficiency in a comprehensive way during SRLG-disjoint working path and backup path selection. To solve this problem, we motivate the needs to study physical impairment-aware shared-path protection by considering two policies. Policy I uses two SRLG-disjoint least impairment paths as working path and backup path, respectively, and Policy II tries to benefit from both the shortest path and the least impairment path by choosing them intelligently. Analytical and simulation results show: (1) compared with impairment-unawareness, impairment-aware SRLG failure protection performs much better in terms of blocking probability especially with strong physical impairment constraints; (2) impairment-aware SRLG failure protection can significantly reduce physical-layer blocking probability; and (3) the algorithm based on Policy II achieves a good balance between capacity efficiency and physical impairment requirement.     

Impairment-aware ordered scheduling in dual-header optical burst switched networks

Optical burst switching (OBS) is a promising technology for bridging the gap between optical wavelength switching and optical packet switching. Optical signal transmission quality is subject to various types of physical impairment introduced by optical fibers, switching elements, or other network components. The signal degradation due to physical impairment may be significant enough such that the bit-error rate of received signals is unacceptably high at the destination, rendering the signal to not usable. In this article, based on earlier study, we study the burst-scheduling problem in OBS networks using two control packets for each data burst, taking into account physical impairment effects. We propose a burst-scheduling algorithm that accommodates incoming bursts by primary path routing, deflection routing, and burst scheduling. We design an admission control mechanism to use network resources efficiently. At an OBS node, the proposed algorithm schedules bursts for transmission by searching for available resources as well as verifying signal quality. Our simulation results demonstrate that the proposed algorithm is effective in terms of reducing the burst-blocking probability.     

基于超图模型的多域ASON损伤感知组播路由算法

如何在缺乏全局信息的条件下构建安全可靠的组 播树,是智能光网络分域管理后引入的一个新问 题。针对此问题,通过建立新型的多域智能光网络超图模型,在考虑物理或攻击损伤的约束 条件下,利用 基于超路径的域间超树构建方法,结合K最短路径策略,提出了 一种基于超图模型的多域ASON损伤感知 组播路由算法,并进行了实例分析。本文算法在完成多域组播路由建立与波长分配的同时, 具有较低的时间复杂度。通过测量K值、组播规 模、波长数量及分配策略、域数量对网络平均连接阻塞率的影响,实验结果表明,本文算法 是有效的且取得了较好的阻塞性能,同时建议多域ASON组播规模大小应与域的数量保持一 定的比例均衡。     

短波宽带波形干扰抑制技术

短波宽带波形是现代短波通信的最新研究成果,采用带宽扩展方式实现短波高速通信。短波信道存在的各种各样强干扰信号使得干扰抑制成为现代短波宽带通信急待解决关键问题之一。针对这种现象,提出了一种基于变换域选择的双门限干扰抑制方法,该算法可以有效地选择最佳变换域去抑制干扰。仿真结果表明这种干扰抑制方法能够抑制不同类型干扰信号,在干扰环境下短波宽带波形具有较好传输性能。     

Equivariant adaptive selective transmission

In this paper, we consider the problem of selective transmission-the dual of the blind source separation task-in which a set of independent source signals are adaptively premixed prior to a nondispersive physical mixing process so that each source can be independently monitored in the far field. Following similar procedures for information-theoretic blind source separation, we derive a stochastic gradient algorithm for iteratively estimating the premixing matrix in the selective transmission problem, and through a simple modification, we obtain a second algorithm whose performance is equivariant with respect to the channel's mixing characteristics. The local stability conditions for the algorithms about any selective transmission solution are shown to be the same as those for similar source separation algorithms. Practical implementation issues are discussed, including the estimation of the combined system matrix and the reordering and scaling of the received signals within the algorithm. Mean square error-based selective transmission algorithms are also derived for performance comparison purposes. Simulations indicate the useful behavior of the premixing algorithms for selective transmission     

如何提高有线电视信号传输质量

针对有线电视信号的使用也越来越广泛,本文将结合有线电视信号的构成以及传输方式,探讨影响有线电视信号传输质量的因素,并结合这些因素进一步阐述提高有线电视信号传输质量的方法和措施。