OSNR comprehensive-awareness model based lightpath control scheme in an OpenFlow controlled all-optical network

To enhance the communication quality of OpenFlow controlled all-optical networks, an optical signal-to-noise ratio comprehensive-awareness (OSNR-CA) model based lightpath control scheme is proposed. This approach transforms main physical-layer optical impairments into OSNR value, and takes this comprehensive OSNR value of the optical signal along the lightpath into consideration, when establishing the lightpath for the connection request using OpenFlow protocol. Moreover, the proposed scheme makes full advantages of the OSNR monitoring function in each node, and assigns the lightpath according to the comprehensive-OSNR value by extending messages of OpenFlow protocol, in order to guarantee the reliable establishment of the lightpath. The simulation results show that the proposed scheme has better performance in terms of packet loss rate and lightpath establishment time.     

An Optical Wavelength-Routed Multicast Packet Switch Based on Multitimeslot Multiwavelength Conversion

This letter presents a new scheme to realize multicast operation in a wavelength-routed optical packet switch by adding multicast modules. The proposed multicasting scheme is based on multitimeslot multiwavelength conversion in conjunction with wavelength selection to resolve the problem of output contention.      

基于SDH的ASON中光组播技术的研究

文章首先简要分析了基于SDH的自动交换光网络(ASON)中光组播的功能需求,然后讨论了在基于SDH的ASON环境下实现组播的几种业务建立模型,最后从功能框架、信令扩展和实现流程等方面对具体实现方案进行了探讨。     

A novel WDM passive optical network architecture supporting two independent multicast data streams

We propose a novel scheme to perform optical multicast overlay of two independent multicast data streams on a wavelength-division-multiplexed (WDM) passive optical network. By controlling a sinusoidal clock signal and shifting the wavelength at the optical line terminal (OLT), the delivery of the two multicast data, being carried by the generated optical tones, can be independently and flexibly controlled. Simultaneous transmission of 10-Gb/s unicast downstream and upstream data as well as two independent 10-Gb/s multicast data was successfully demonstrated.     

基于光森林的弹性光网络能效组播路由频谱分配策略

在弹性光网络中,光树传输组播可以节省链路代价,但较长的光树需要选择更低的调制等级,消耗更多的频谱资源和发射机功耗.提出一种基于遗传算法的光森林组播和光树重配置(GAMF-TR)优化组播的能效路由、调制格式和频谱分配(RMSA)策略.GAMF-TR策略设计染色体编码表示光森林的组播目的节点划分和光路径组合,通过染色体的基因位概率交叉和变异得到更多的光森林RMSA策略,设计了一个频谱分配效率和发射机功耗折中的适应度函数选择能效最高的光森林RMSA策略,并设计在网络资源充足时将组播从光森林重配置到光树传输,进一步减少发射机功耗的消耗.仿真结果表明:提出的GAMF-TR策略获得了组播的最低带宽阻塞率和最高能效性能.     

利用FDL实现OBS网络中的组播业务

本文给出了一种OBS网络中组播业务的实现机制。它利用由光分路器和光纤延迟线（FDL）构成的组播功能模块实现了组播数据包在多分支节点处的复制、存储以及转发。仿真分析结果表明，该机制可以通过引入一定的时延，大幅降低丢包率。     

Contention resolution considering multicast traffic in optically burst-switched WDM networks

This paper proposes a contention resolution scheme considering multicast traffic in optical burst switching (OBS) networks. In OBS networks, for unicast bursts, contention can be avoided by deflection routing. However, deflection routing cannot be applied to multicast bursts because multicast bursts are transmitted along light-trees which are fixed, tree-shaped routes. Therefore, the loss probability of multicast bursts is generally high. To resolve this problem, the proposed scheme introduces an ingenious offset time assignment strategy which completely avoids contention of multicast bursts due to transmissions of unicast bursts by strategically assigning additional offset times. Furthermore, in the proposed scheme, unicast bursts avoid contention with deflection routing. Through simulation experiments, we show that the proposed scheme improves the loss probabilities of both of unicast bursts and multicast bursts.     

一种基于OFDMA的无线多播比例公平调度方案

为了在无线多播网络中提高系统吞吐量,该文提出了一种新型的多播组间公平的无线资源分配方案。方案在保证公平分配无线资源的基础之上,运用设置平均误块率门限的方法,在系统的多用户分集增益和多播增益之间找到了最佳平衡,从而提高了系统的吞吐量。理论和仿真分析表明,与已有的传统多播方案相比,该方案在保证误块率不超过用户忍受的最高限度时,系统能够提供更高的吞吐量。该方案在实际应用中,具有一定的可行性和可操作性。     

A Multicast WDM-PON Architecture Using DPSK/NRZ Orthogonal Modulation

We propose a novel scheme to overlay multicast data on a wavelength-division-multiplexed passive optical network (WDM-PON) with point-to-point data delivery. The differential phase-shift keying multicast signal is superimposed onto all point-to-point nonreturn-to-zero (NRZ) signals. By adjusting the extinction ratios of the individual NRZ point-to-point signals, multicast can be realized and only the designated optical network units can properly receive the multicast data. We successfully demonstrated the proposed WDM-PON with 10-Gb/s downstream point-to-point signals and 10-Gb/s multicast signals.      

基于共享路径和网络编码的光组播容量优化

为了降低光组播路由 的光域网络编码代价和提高达到理论最大光组播容量的 概率,提出一种基于共享链路和网络编 码的优化光组播容量方法。首先设计一种从多条源－ 宿最短路径中选择能达到最大光组播容量的最短路径簇,然后在 最短路径簇中计算路径的共享度,选择共享度高的组播路径传输网络编码信息,构造网络编 码次数最少的光组播编码子图, 解决传统的网络编码组 播路由和最大共享度链路组播路由中存在的网络编码次数过多和达到最大光组播容量概率过 低的问 题。仿真结果表明:本文提出的方法具有最低的网络编码代价,能以最大的概率达到光组播 理论最大容量。     

基于无色无向无冲突可重构光分插复用器节点的全光IP组播能效调度

为了提高无色无向无冲突灵活的可重构光分插复用器(CDC-F ROADM)节点的弹性光网络IP组播频谱-能耗效率,该文提出一种全光组播能效调度算法(AMEESA)。在算法路由阶段,考虑能耗和链路频谱资源使用情况设计链路代价函数,构建最小代价光树算法组播光树。在频谱分配阶段,设计基于高效光谱分辨率(HSR)光树中间节点频谱转换方法,选择节能频谱转换方案为组播光树分配频谱块资源。仿真分析表明,所提算法能有效提升网络能效,降低IP组播带宽阻塞率。     

Optimized layered multicast with superposition coding in cellular systems

We consider the problem of optimal power allocation and optimal user selection in a layered multicast transmission over quasi‐static Rayleigh fading channels. A scheme based on superposition coding is proposed in which basic multicast streams and enhanced multicast streams are superimposed and transmitted by a base station, while users with worse channel conditions can only decode basic multicast streams, and users with better channel conditions can decode both basic and enhanced multicast streams. In this paper, subject to fixed user selection ratios, the optimal power allocation for each stream that maximizes average throughput is investigated, and the impact of power allocation on average outage probability is discussed. Finally, subject to fixed transmit power and power allocation, the optimal user selection ratio for enhanced multicast streams is also studied. Numerical results show that the optimized layered multicast scheme outperforms the conventional multicast scheme in terms of average throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

Optical multicast provisioning with differentiated leaf availability guarantee in WDM networks

As multicast applications become more and more popular, implementing multicast in the optical domain has attracted increased attention due to its more efficient bandwidth usage. And also these services have quality-of-service requirements. In this article, the problem of cost-effective optical multicast provisioning to satisfy the differentiated leaf availability requirements is formally stated. A Mixed Integer Linear Program formulation is proposed for provisioning dedicated light-tree protection with differentiated leaf availability guarantee. The algorithm is so complex and infeasible that we also propose a feasible two-step approximate approach to solve the problem. Different from the previous schemes, our scheme finds out the primary light-trees and backup paths for destination nodes whose availability is not satisfied. Because of taking the different leaf availability requirements into account, the proposed algorithm obtains a more efficient feasible solution requiring less network resources.     

基于数字证书的树型结构安全多播方案

该文提出一种基于数字证书的安全多播方案，采用树型的多播拓扑结构。多播树中的每个节点都有一个标识其身份的数字证书，除了成员身份认证外，还可以安全地分发会话密钥和实现会话数据的认证，因而减少了多播群密钥管理的复杂度；由于采用分层的树型多播结构，成员加入和退出有了更大的可扩展性。     

一种基于混合策略的动态组播密钥管理方案

组播密钥管理是当前组播安全研究的热点问题。在分析现有方案的基础上，考虑一种混合策略：将基于组的层次结构机制Iolus与基于密钥层次结构机制LKH的优点结合起来，提出了一种适合大型动态组播的可扩展的分层分组方式的密钥管理方案。该方案有效地降低了密钥更新的代价，具有较高的效率与较好的可扩展性．适合于解决大型动态组播的密钥管理问题。     

Design of a node architecture for logic-calculation Nased all-optical network coding scheme

Network coding brings many benefits for multicast networks. It is necessary to introduce network coding into optical networks. Nevertheless, the traditional network coding scheme is hard to be implemented in optical networks because of the weak operation capability in photonic domain. In the paper, we focused on realizing two-channel network coding in all-optical multicast networks. An optical network coding scheme which can be realized via logic shift and logic XOR operations in photonic domain was proposed. Moreover, to perform the network coding scheme the coding node structure was designed and the operation principle and processes were illustrated in detail. In the end of the paper, the performance and the cost of different all-optical multicast mode were compared and analyzed.     

Bandwidth-satisfied multicast trees in large-scale ad-hoc networks

The purpose of this paper is to construct bandwidth-satisfied multicast trees for QoS applications in large-scale ad-hoc networks (MANETs). Recent routing protocols and multicast protocols in large-scale MANETs adopt two-tier infrastructures to avoid the inefficiency of the flooding. Hosts with a maximal number of neighbors are often chosen as backbone hosts (BHs) to forward packets. Most likely, these BHs will be traffic concentrations/bottlenecks of the network. In addition, since host mobility is not taken into consideration in BH selection, these two-tier schemes will suffer from more lost packets if highly mobile hosts are selected as BHs. In this paper, a new multicast protocol is proposed for partitioning large-scale MANET into two-tier infrastructures. In the proposed two-tier multicast protocol, hosts with fewer hops and longer remaining connection time to the other hosts will be selected as BHs. The objective is not only to obtain short and stable multicast routes, but also to construct a stable two-tier infrastructure with fewer lost packets. Further, previous MANET quality-of-service (QoS) routing/multicasting protocols determined bandwidth-satisfied routes for QoS applications. Some are implemented as a probing scheme, but the scheme is inefficient due to high overhead and slow response. On the contrary, the others are implemented by taking advantage of routing and link information to reduce the inefficiency. However, the latter scheme suffers from two bandwidth-violation problems. In this paper, a novel algorithm is proposed to avoid the two problems, and it is integrated with the proposed two-tier multicast protocol to construct bandwidth-satisfied multicast trees for QoS applications in large-scale MANETs. The proposed algorithm aims to achieve better network performance by minimizing the number of forwarders in a tree.     

Topology based placement of multicast capable nodes for supporting efficient multicast communication in WDM optical networks

Most existing algorithms for the problem of optical signal splitter placement or multicast splitting-capable node placement in a WDM network are based on the performance of attempting a large set of randomly generated multicast sessions in the network. Experiments show that placement of multicast capable nodes based on their importance for routing one set of multicast sessions may not be a right choice for another set of multicast sessions. In this work, we propose placement algorithms that are based on network topology and the relative importance of a node in routing multicast sessions, which is measured by our proposed metrics. Since a network topology is fixed once given, the proposed algorithms are essentially network traffic independent. We evaluate the proposed placement algorithms given static sets of multicast sessions as well as under dynamic traffic conditions, which are routed using our splitter constrained multicast routing algorithm. Our results show that the proposed algorithms perform better, compared to existing algorithms.     

On Finding the Multicast Protection Tree Considering SRLG in WDM Optical Networks

In this letter, a new sharing mechanism, SRLG sharing, is proposed, which allows the links of the same shared risk link group (SRLG) in a primary light tree to share protections in WDM optical networks. In previous studies, how to share spare resources with SRLG constraints has not been studied in multicast optical networks. In this letter, considering SRLG sharing, we propose a novel algorithm –multicast with SRLG sharing (MSS)– to establish a protection light tree. Finally, the algorithm MSS and the algorithm multicast with no SRLG sharing (MNSS) are compared through a simulation to show that our new sharing scheme of SRLG sharing is more efficient than that of no SRLG sharing in terms of spare resource utilization and blocking probability.     

基于多条件约束的ASON动态组播路由算法

在将自动交换光网络(ASON)建模成着色多重图的基础上采用综合成本策略,设计了一种新的最小综合成本路径计算算法,并结合组播成员的动态变化特性提出一种满足多条件约束的动态组播路由(DMRMC)算法,使组播路由和波长分配在同一过程内完成,且尽可能使组播树的综合总成本最小,同时局部优化波长转换次数、分光次数和不同波长的使用数量。仿真实验表明,本文算法有效可行,与采用单成本策略的组播算法相比,其取得了更低的综合成本和更好的连接阻塞性能。