光纤网络中云计算资源联合最优分配方法

在云计算技术与光纤网络不断发展的今天,网络数据不断增加,网络带宽面临严峻挑战。当前应用云计算资源联合最优分配方法对网络链路资源分配的结果较为落后,导致资源分配后网络数据传输扰动量以及带宽阻塞率较高。针对此问题,本文设计光纤网络中云计算资源联合最优分配方法。以网络任务模型为蓝本,构建光纤网络传输模型。将光纤网络传输模型以有向图的形式,完成网络节点传输映射分析。结合光树生成算法,设计云计算资源最优分配算法,完成光纤网络中云计算资源联合最优分配方法设计。仿真结果表明：采用所提方法后网络数据传输扰动量以及带宽阻塞率较低,提升了云计算资源的分配方法。     

A sub-optimal joint subcarrier and power allocation algorithm for multiuser OFDM

This paper investigates subcarrier and power allocation in multiuser OFDM. The aim is to maximize the overall rate while achieving proportional fairness amongst users under a total power constraint. Achieving the optimal solution is computationally demanding thereby necessitating the use of sub-optimal techniques. Existing sub-optimal techniques either use fixed power allocation and perform only subcarrier allocation or handle subcarrier and power allocation separately. In this paper, we propose an algorithm that performs joint subcarrier and power allocation. Simulation results are shown to compare the performance of the proposed algorithm with that of existing algorithms.     

Iterative multiuser joint decoding: optimal power allocation and low-complexity implementation

We consider a canonical model for coded code-division multiple access (CDMA) with random spreading, where the receiver makes use of iterative belief-propagation (BP) joint decoding. We provide simple density-evolution analysis in the large-system limit (large number of users) of the performance of the BP decoder and of some suboptimal approximations based on interference cancellation (IC). Based on this analysis, we optimize the received user signal-to-noise ratio (SNR) distribution in order to maximize the system spectral efficiency for given user channel codes, channel load (users per chip), and target user bit-error rate (BER). The optimization of the received SNR distribution is obtained by solving a simple linear program and can be easily incorporated into practical power control algorithms. Remarkably, under the optimized SNR assignment, the suboptimal minimum mean-square error (MMSE) IC-based decoder performs almost as well as the more complex BP decoder. Moreover, for a large class of commonly used convolutional codes, we observe that the optimized SNR distribution consists of a finite number of discrete SNR levels. Based on this observation, we provide a low-complexity approximation of the MMSE-IC decoder that suffers from very small performance degradation while attaining considerable savings in complexity. As by-products of this work, we obtain a closed-form expression of the multiuser efficiency (ME) of power-mismatched MMSE filters in the large-system limit, and we extend the analysis of the symbol-by-symbol maximum a posteriori probability (MAP) multiuser detector in the large-system limit to the case of nonconstant user powers and nonuniform symbol prior probabilities.     

Autonomic traffic engineering for network robustness

The continuously increasing complexity of communication networks and the increasing diversity and unpredictability of traffic demand has led to a consensus view that the automation of the management process is inevitable. Currently, network and service management techniques are mostly manual, requiring human intervention, and leading to slow response times, high costs, and customer dissatisfaction. In this paper we present AutoNet, a self-organizing management system for core networks where robustness to environmental changes, namely traffic shifts, topology changes, and community of interest is viewed as critical. A framework to design robust control strategies for autonomic networks is proposed. The requirements of the network are translated to graph-theoretic metrics and the management system attempts to automatically evolve to a stable and robust control point by optimizing these metrics. The management approach is inspired by ideas from evolutionary science where a metric, network criticality, measures the survival value or robustness of a particular network configuration. In our system, network criticality is a measure of the robustness of the network to environmental changes. The control system is designed to direct the evolution of the system state in the direction of increasing robustness. As an application of our framework, we propose a traffic engineering method in which different paths are ranked based on their robustness measure, and the best path is selected to route the flow. The choice of the path is in the direction of preserving the robustness of the network to the unforeseen changes in topology and traffic demands. Furthermore, we develop a method for capacity assignment to optimize the robustness of the network.     

一种基于OFDM的多用户认知无线电系统联合资源分配算法

针对频谱共享环境,研究了采用OFDM调制方式的多用户认知无线电系统中,综合考虑自身发射功率约束与主用户干扰功率约束的资源分配问题.基于最大化认知用户和速率的优化目标,给出了连续比特条件下最优的多水位注水功率分配表达式;针对更实际的整数比特要求情况,通过基于相对增益因子RG的子信道选择机制与每个认知用户内多约束的贪婪比特与功率分配策略,来最大限度地提高频谱利用率.仿真结果表明:联合的子信道、功率与比特分配算法在不同的参数设置下均达到了良好的性能,在不影响主用户通信的前提下有效地提高了认知系统的频谱利用率.     

Scheduling and allocation in high-level synthesis using stochastic techniques

High-level synthesis is the process of automatically translating abstract behavioral models of digital systems to implementable hardware. Operation scheduling and hardware allocation are the two most important phases in the synthesis of circuits from behavioral specification. Scheduling and allocation can be formulated as an optimization problem. In this work, a unique approach to scheduling and allocation problem using the genetic algorithm (GA) is described. This approach is different from a previous attempt using GA (Wehn et al., IFIP Working Conference on Logic and Architecture Synthesis, Paris, 1990, pp. 47–56) in many respects. The main contributions include: (1) a new chromosomal representation for scheduling and for two subproblems of allocation; and (2) two novel crossover operators to generate legal schedules. In addition the application of tabu search (TS) to scheduling and allocation is also implemented and studied. Two implementations of TS are reported and compared. Both genetic scheduling and allocation (GSA) and tabu scheduling and allocation (TSA) have been tested on various benchmarks and results obtained for data-oriented control-data flow graphs are compared with other implementations in the literature. (A discussion on GSA was presented at the European Design Automation Conference Euro-DAC'94 in Grenoble, France, and TSA at the International Conference on Electronics, Circuits and Systems — ICECS'94 in Cairo, Egypt.) A novel interconnect optimization technique using the GA is also realized.     

IP network configuration for intradomain traffic engineering

The smooth operation of the Internet depends on the careful configuration of routers in thousands of autonomous systems throughout the world. Configuring routers is extremely complicated because of the diversity of network equipment, the large number of configuration options, and the interaction of configuration parameters across multiple routers. Network operators have limited tools to aid in configuring large backbone networks. Manual configuration of individual routers can introduce errors and inconsistencies with unforeseen consequences for the operational network. In this article we describe how to identify configuration mistakes by parsing and analyzing configuration data extracted from the various routers. We first present an overview of IP networking from the viewpoint of an Internet service provider and describe the kinds of errors that can appear within and across router configuration files. To narrow the scope of the problem, we then focus our attention on the configuration commands that relate to traffic engineering-tuning the intradomain routing protocol to control the flow of traffic through the ISP network. We present a case study of a prototype tool, developed in collaboration with AT&T IP Services, for checking the configuration of the AT&T IP Backbone and providing input to other systems visualization and traffic engineering     

面向5G网络切片无线资源分配

未来网络需要满足多种应用场景在时延、可靠性和速率等方面的不同要求,然而只构建一种网络难以满足所有应用场景的需求.网络切片技术即在一个物理基础设施之上构建多个逻辑网络以满足不同类型应用场景的需求,能够实现专用电信网络所具有的所有功能,且用户感受不到差别.无线接入网切片是端到端网络切片的一部分,而无线资源分配又是无线接入网切片的重要内容.本文提出了一种基于比例公平算法的半静态资源分配方案,在各网络切片之间实现更公平的资源分配.仿真结果对比了三种资源分配方案,半静态资源分配方案获得的公平性优于其他两种资源分配方案.     

面向卫星网络的流量工程路由算法

针对卫星网络链路长时延、拓扑时变等特征,将链路传输时延引入并基于MPLS网络中源-目的节点对已知这一先验知识,提出了一种面向卫星网络的MPLS流量工程路由算法。该算法基于卫星网络时变拓扑模型的卫星拓扑快照,定义链路初始权重为链路剩余带宽、传输时延的综合函数,在为当前节点对建路时考虑其余节点对将来建路的可能需求计算链路的关键度,在此基础上通过链路权重的动态调整及延期选用实现流量工程,从而优化卫星网络的链路利用。实验表明,此算法在请求拒绝数、吞吐量、平均跳数及平均时延等方面性能都有较理想的提升。     

大规模高速网络流量工程研究

主要讨论互联网主干上的流量工程。由于现在路由协议使网络的低效率和新的应用的出现，迫切要求发展新的技术、引进流量工程的观点来处理这些问题。介绍了MPLS等的新的IP交换技术及其相关的路由算法；讨论了在IP主干上电话传输技术。     

Virtual path bandwidth allocation in multiuser networks

We consider a multiuser network that is shared by noncooperative users. Each user sets up virtual paths that optimize its own selfish performance measure. This measure accounts for the guaranteed call level quality of service, as well as for the cost incurred for reserving the resource. The interaction among the user strategies is formalized as a noncooperative game. We show that the game has a unique Nash equilibrium and that it possesses a certain fairness property. We investigate the dynamics of this game and prove convergence to the Nash equilibrium of both a Gauss-Seidel scheme and a Jacobi scheme. We extend our study to various general network topologies. Finally, the formal results and some extensions thereof are tested by emulating the schemes on an experimental network     

分段路由网络研究及其在流量工程中的应用

分段路由网络是对IP路由技术的继承和创新,在实现网络虚拟化、快速重路由、网络可编程、负载均衡和流量工程等方面具有独特优势.深入研究了分段路由的实现机制,全面介绍和剖析了IGP和BGP支持分段路由网络的协议扩展,探讨了分段路由在运营商网络中典型应用场景的流量工程实现.随着技术的成熟和标准的完善,分段路由网络将具有广阔的应用前景.     

An hybrid evolutionary multiobjective algorithm for multiuser margin maximization in DSL

This work describes and proposes the application of evolutionary algorithms on the multiuser spectrum and SNR margin optimization problem for multicarrier systems, such as digital subscriber line. The proposed method is designed such that it takes advantage of special characteristics of the well‐known power adaptation techniques and uses them to solve the broader and more challenging problem of multiuser margin adaptation. Simulations show that the proposed method provides Pareto‐optimal and diverse solutions when compared to a previous method to solve the same problem. Copyright © 2014 John Wiley & Sons, Ltd.     

Stochastic traffic engineering for demand uncertainty and risk-aware network revenue management

We present a stochastic traffic engineering framework for optimizing bandwidth provisioning and route selection in networks. The objective is to maximize revenue from serving demands, which are uncertain and specified by probability distributions. We consider heterogenous demands with different unit revenues and uncertainties. Based on mean-risk analysis, the optimization model enables a carrier to maximize mean revenue and contain the risk that the revenue falls below an acceptable level. Our framework is intended for off-line traffic engineering design, which takes a centralized view of network topology, link capacity, and demand. We obtain conditions under which the optimization problem is an instance of convex programming and therefore efficiently solvable. We also study the properties of the solution and show that it asymptotically meets the stochastic efficiency criterion. We derive properties of the optimal solution for the special case of Gaussian distributions of demands. We focus on the impact of demand uncertainty on various aspects of traffic engineering, such as link utilization, bandwidth provisioning and total revenue. The carrier's tolerance to risk is shown to have a strong influence on traffic engineering and revenue management decisions. We develop the efficient frontier, which is the entire set of Pareto optimal pairs of mean revenue and revenue risk, to aid the carrier in selecting an appropriate operating point.     

基于SDN的IP网络流量工程问题研究

文章以SDN为基础,对IP网络流量工程进行分析和研究,探讨了IP网络流量工程的实现原理、技术及功能模块,对IP流量工程的实现流程进行了分析,经过验证可知,文章提出的基于SDN的IP网络流量工程准确性和有效性良好。     

Dynamic market‐driven allocation of network resources using genetic algorithms in a competitive electronic commerce marketplace

In this paper, we propose a practical algorithm which finds cost‐efficient routes from Service Provider (SP) to Content Provider (CP) dynamically in a multi‐operator networking environment, using Genetic Algorithm (GA) concepts. The proposed algorithm is a kind of stochastic algorithm searching process in the solution space by emulating biological selection and reproduction. Copyright © 2001 John Wiley & Sons, Ltd.     

On the network utility optimal allocation of radio resources in WCDMA systems

We discuss an optimization framework for radio resource allocation in a WCDMA system supporting elastic traffic. In particular, we assume the users' preferences as driven by utility functions depending on the assigned transmission rate, and the network capacity constraints as related to interference and power limitations. In this framework, we perform the constrained instantaneous network utility maximization through a logarithmic barrier method. The obtained results are compared and discussed.     

WDM光网络中静态业务的P-cycle保护

P-cycle是一种预先配置的保护方式,在WDM网络中,P-cycle可以提供快速保护倒换和很高的资源利用率,具有很好的应用前景和研究价值.文章研究了P-cycle对于WDM网络中静态业务的保护情况,得出了基本的P-cycle配置策略下的仿真数据,并进行了分析.     

多用户OFDM系统子载波分配算法研究

采用改进的贪婪算法分配时隙的无线资源,根据用户业务的QoS和数据队列信息确定用户的优先权,并在获知信道状态信息条件下,按照传输比特消耗功率最小原则搜索所有子载波信道,为用户动态分配子载波和比特。仿真结果表明,在两种传输速率要求下,当接入用户数相同时,改进算法比传统贪婪算法减少功率消耗3.9622W;改进算法多消耗1.9858W功率却增加了2个接入用户,用户消耗平均功率比前者少2.2456W/用户。