电信网络成本研究

电信网络成本是电信管制经济学的基础。目前中国尚无系统的电信网络成本工程学测算模型，以工程学分析模型为主结合计量经济学方法来研究电信网络成本是电信网络成本工程学研究的主要问题。使用网络成本工程学方法对电信网络成本进行研究，可以在电信管制经济学基础研究方面有所突破。文章介绍了电信网络成本的研究现状、研究内容、研究目标和关键问题，以及采用工程学模型方法测算电信网络成本的主要特色与创新之处。     

面向城市交通网络的一种新型动态路径寻优方法

 针对静态路径寻优方法中没有考虑到交通流随时间变化的问题,本文提出一种基于交通流量预测的路径寻优方法.首先,从实际交通路网本身的特点和人类对路网的认识出发,构建以"道路"为基本元素的新型路网模型;其次,采用基于单变量时间序列的预测方法对路网上各路段未来一段时间内的道路交通流量进行预测,并根据预测结果估计出行者在未来时段各路段上的交通代价;再次,通过估计的交通代价把车辆从起点到该路段时间内的道路交通变化状况融入改进A^*算法的路径搜索过程,从而建立一种高效的动态改进A^*路径搜索算法;最后,实例表明预测交通流量与实际交通流量具有很好的拟合度,路径搜索结果能够对出行者起到诱导作用,提高出行者行驶效率.     

A Convolution Universal Generating Function Method for Evaluating the Symbolic One-to-All-Target-Subset Reliability Function of Acyclic Multi-State Information Networks

The acyclic multi-state information network (AMIN) is an extension of the multi-state network without having to satisfy the flow conservation law. A very straightforward convolution universal generating function method (CUGFM) is developed to find the exact symbolic one-to-all-target-subset reliability function of AMIN. The correctness and computational complexity of the proposed algorithm will be proven. Two illustrative examples demonstrate the power of the proposed CUGFM to solve the exact symbolic reliability functions of the one-to-all-target-subset AMIN problem more efficiently than the best-known UGFM.     

Reliability Analysis of Redundant Networks Using Flow Graphs

A flow graph approach for reliability analysis is applied to redundancy with elements in the simple series-parallel networks and to the more general case with elements in non-series-parallel combinations. The reliability of networks for elements with open or short failures is analyzed with flow graphs. Typical examples are shown.     

Information Theoretic Approach to Traffic Adaptive WDM Networks

WDM networks adapt to the changes in traffic by reconfiguring the virtual topology. Though reconfiguration is done with the objective of utilizing resources efficiently, the resulting disruption in traffic is a cause for concern. Hence, policies are formed to decide on the time (i.e., when) to trigger reconfiguration and the new virtual topology that is most beneficial to the network. We present a simple, general and flexible framework, based on the two conflicting objectives of efficient resource utilization and minimizing traffic disruption, to evaluate reconfiguration policies. Instead of re-determining the reconfiguration policy whenever the traffic changes, we present Incremental Clustering Algorithm (ICA) to pre-plan the reconfiguration policy for a fully predictable finite sequence of traffic matrices. Since full predictability of such a sequence is not possible in practice, we learn the traffic sequences in order to probabilistically predict the future ones. From an information theoretic point of view, we quantify the predictability of traffic sequences and the number of times the reconfiguration policy is re-determined for any WDM network. To optimally predict the future traffic sequences and to incur optimal cost in the re-determination of the reconfiguration policy, we propose Universal Reconfiguration Management System (URMS). A Prediction-based Incremental Clustering Algorithm (PICA) that extends ICA is used by URMS to predict the reconfiguration policy. Within URMS, the probabilities are assigned to the traffic sequences by the prediction schemes of LZ78. We performed extensive simulations to study the effectiveness and efficiency of URMS when compared to the fully predictable and totally unpredictable models. The performance of URMS improves with learning and nearly achieves the performance of a fully predictable model.     

基于神经网络的业务量预测研究

分别采用back—propagation（BP）算法和Favidon最小二乘学习算法训练神经网络（NN），并用于复杂业务流量预测。以自相似流量模型验证了2种NN学习算法的有效性，并分析比较了他们在流量预测中的可行性，得出Davidon最小二乘学习算法训练的NN比BP算法收敛速度快、收敛误差相差不多，验证了复杂自相似业务流的可预测性，为复杂自相似网络业务流预测的研究提供了一种有效途径。     

利用多协议标记交换技术实现IP网的流量工程

文章概述了基于集成模式的新一代技术——多协议标记交换技术(MPLS)产生的原动力及其良好的应用前景,并通过对IP网络中流量工程技术发展阶段的分析,比较了各种流量工程技术的差异及优缺点,重点研究了基于MPLS技术实现IP网络中流量工程的工作原理,并以深训市IP城域网为例作了具体说明。     

Quality-of-Service in Evolving Telecommunications Networks

This paper addresses the problem of achieving overall quality-of-service of telecommunications networks in North America, following the divestiture of AT&T and the resulting competitive multivendor environment. The paper outlines an approach based onbulleta top-down process in which quality-of-service is designed into networks by individual network vendors in cooperation with coordinating standards bodies, andbulleta bottom-up process in which quality-of-service is verified and controlled under actual network operating conditions.     

Using Discretionary Telecommunications

The network telephone and broadcast video communications that blanket the nation are being exploited broadly for social purposes. Continuing technical effort can help reduce the cost and increase the flexibility of existing systems, thus making them even more attractive for such applications as improving education, increasing productivity, and delivering health care. Advances in technology can provide new opportunities, and there are promising results from R&D in broad-band transmission, image sensing, and graphic displays. However, there is no need to wait for new technology to use discretionary telecommunications for new social purposes. The biggest task is organizing institutions and procedures to use existing telecommunications effectively. And the most important measure of success for a novel application is likely not to be an abstract cost/benefit calculation, but rather the vital market place evaluation of whether anyone wants to support an operational version of an experimental system.     

基于无线Mesh网络的交通信息系统

本文提出了一种基于无线Mesh网络的交通信息系统,系统由探测汽车采集实时交通信息,依托无线Mesh网络将采集得到的信息发送到信息处理中心.该系统能够提供准确实时的路况信息,无需大量固定基础设施支持,具有建设成本低、周期短、维护费用低的特点,特别适合我国交通事业发展的现状.     

多域光网络中一种支持区分可靠性的通路保护算法

区分可靠性的通路保护方案既能为光网络中具有不同可靠性需求的业务提供有效的故障保护,又能优化网络资源的利用,是一种高效的生存性机制。但目前此类问题的研究主要是集中于传统的单域光网络中,所得的研究成果无法直接运用于具有多域特点的下一代光网络中。针对这一问题,在对以往通路保护算法进行改进的基础上提出了一种适用于多域光网络中的支持区分可靠性的通路保护算法,并对其性能进行了计算机仿真研究。仿真结果表明,该算法不仅能满足多域光网络中不同业务的可靠性需求,而且能提高网络资源的利用率、降低业务连接的阻塞率。     

基于神经网络的网络流量预测算法研究

网络流量预测有助于网络服务质量的提升和网络资源的合理分配,对优化网络管理与运营、保障用户体验质量至关重要.因特网业务的急剧增加和基础网络的快速发展导致网络流量变得更加复杂多样,传统网络流量预测模型难以保证较高的预测精度,而神经网络作为人工智能的重要分支,在预测复杂网络流量时具有显著优势.简述反向传播神经网络、径向基神经...     

Efficient Traffic Information Dissemination and Vehicle Navigation for Lower Travel Time in Urban Scenario Using Vehicular Networks

Wireless Personal Communications - Massive MIMO has shown to be a promising candidate for the next generation of mobile communications 5G. Cell free massive MIMO is an implementation in which...     

Road Oriented Traffic Information System for Vehicular Ad hoc Networks

Over the last few years, vehicular ad hoc networks (VANETs) have gained popularity for their interesting applications. To make efficient routing decisions, VANET routing protocols require road traffic density information for which they use density estimation schemes. This paper presents a distributed mechanism for road vehicular density estimation that considers multiple road factors, such as road length and junctions. Extensive simulations are carried out to analyze the effectiveness of the proposed technique. Simulation results suggested that, the proposed technique is more accurate compared to the existing technique. Moreover, it facilitate VANET routing protocols to increase packet delivery ratio and reduce end-to-end delay.     

Tracking Traffic Peaks in Mobile Networks Using Statistics of Performance Metrics

In recent years, there has been an increasing awareness to tracking traffic peaks reflecting the presence of mass events or permanent traffic hotspots. This trend is driven by dominant themes for wireless evolution towards 5G networks such as the problematic of hotspot offloading solutions, the emergence of heterogeneous networks with small cells’ deployment and the development of green networks’ concept. Actually, tracking traffic peaks with a high accuracy is of great interest to know how the congested zones can be offloaded, where small cells should be deployed and how they could be managed for sleep mode concept or even controlled according to traffic mobility if they are moving. In this paper, we propose a method for tracking peaks of traffic using performance metrics extracted from the operation and maintenance database of the network. These metrics are the timing advance, the angle of arrival, the neighboring cell level, the cell load and two mean throughputs: arithmetic (AMT) and harmonic (HMT). The combined use of these performance metrics, projected over a coverage map, yields a promising traffic localization precision even with considering imperfections of coverage prediction and mobile equipment capabilities in handling measurements. The proposed solution can be easily implemented in the network at an appreciable low cost.     

On Security and Reliability Using Cooperative Transmissions in Sensor Networks

Cooperative transmissions have received recent attention and research papers have demonstrated their benefits for wireless networks. Such benefits include improving the reliability of links through diversity and/or increasing the reach of a link compared to a single transmitter transmitting to a single receiver (single-input single-output or SISO). In one form of cooperative transmissions, multiple nodes can act as virtual antenna elements and provide diversity gain or range improvement using space-time coding. In a multi-hop ad hoc or sensor network, a source node can make use of its neighbors as relays with itself to reach an intermediate node with greater reliability or at a larger distance than otherwise possible. The intermediate node will use its neighbors in a similar manner and this process continues till the destination is reached. Thus, for the same reliability of a link as SISO, the number of hops between a source and destination may be reduced using cooperative transmissions as each hop spans a larger distance. However, the presence of malicious or compromised nodes in the network impacts the benefits obtained with cooperative transmissions. Using more relays can increase the reach of a link, but if one or more relays are malicious, the transmission may fail. However, the relationships between the number of relays, the number of hops, and success probabilities are not trivial to determine. In this paper, we analyze this problem to understand the conditions under which cooperative transmissions fare better or worse than SISO transmissions. We take into consideration additional parameters such as the path-loss exponent and provide a framework that allows us to evaluate the conditions when cooperative transmissions are better than SISO transmissions. This analysis provides insights that can be employed before resorting to simulations or experimentation.     

Survivability Approaches Using p-Cycles in WDM Mesh Networks Under Static Traffic

The major challenge in survivable mesh networks is the design of resource allocation algorithms that allocate network resources efficiently while at the same time are able to recover from a failure quickly. This issue is particularly more challenging in optical networks operating under wavelength continuity constraint, where the same wavelength must be assigned on all links in the selected path. This paper proposes two approaches to solve the survivable routing and wavelength assignment RWA problem under static traffic using p-cycles techniques. The first is a non-jointly approach, where the minimum backup capacity against any single span failure is set up first. Then the working lightpaths problem is solved by first generating the most likely candidate routes for each source and destination s-d pair. These candidate routes are then used to formulate the overall problem as an ILP problem. Alternatively, for a more optimum solution, the problem can be solved jointly, where the working routes and the backup p-cycles are jointly formulated as an ILP problem to minimize the total capacity required. Furthermore, only a subset of high merit cycles that are most likely able to protect the proposed working paths is used in the formulation. Reducing the number of candidate cycles in the final formulation plays a significant role in reducing the number of variables required to solve the problem. To reduce the number of candidate cycles in the formulation, a new metric called Route Sensitive Efficiency (RSE) - has been introduced to pre-select a reduced number of high merit cycle candidates. The RSE ranks each cycle based on the number of links of the primary candidate routes that it can protect. The two approaches were tested and their performances were compared.     

Transmission-Efficient Routing in Wireless Networks Using Link-State Information

The efficiency with which the routing protocol of a multihop packet-radio network uses transmission bandwidth is critical to the ability of the network nodes to conserve energy. We present and verify the source-tree adaptive routing (STAR) protocol, which we show through simulation experiments to be far more efficient than both table-driven and on-demand routing protocols proposed for wireless networks in the recent past. A router in STAR communicates to its neighbors the parameters of its source routing tree, which consists of each link that the router needs to reach every destination. To conserve transmission bandwidth and energy, a router transmits changes to its source routing tree only when the router detects new destinations, the possibility of looping, or the possibility of node failures or network partitions. Simulation results show that STAR is an order of magnitude more efficient than any topology-broadcast protocol proposed to date and depending on the scenario is up to six times more efficient than the Dynamic Source Routing (DSR) protocol, which has been shown to be one of the best performing on-demand routing protocols.     

Wavelength Selection in OBS Networks Using Traffic Engineering and Priority-Based Concepts

A fundamental assumption underlying most studies of optical burst switched (OBS) networks is that full wavelength conversion is available throughout the network. In practice, however, economic and technical considerations are likely to dictate a more limited and sparse deployment of wavelength converters in the optical network. Therefore, we expect wavelength assignment policies to be an important component of OBS networks. In this paper, we explain why wavelength selection schemes developed for wavelength routed (circuit-switched) networks are not appropriate for OBS. We then develop a suite of adaptive and nonadaptive policies for OBS switches. We also apply traffic engineering techniques to reduce wavelength contention through traffic isolation. Our performance study indicates that, in the absence of full conversion capabilities, intelligent choices in assigning wavelengths to bursts at the source can have a profound effect on the burst drop probability in an OBS network.     

电信技术的发展与传统电信网络革新[7]

9 传统电信网络的革新之路 基础网络设施 (如管道、光缆、铜缆和机房等 )、已有的客户群、丰富的运营经验、完善的运营体系、电信级的服务信誉是传统电信运营商最宝贵的资源和最大的竞争优势.在电信技术飞速发展、电信竞争日趋激烈、电信行业赢利越来越困难的新形势下,传统电信运营商如何通过网络的演进和革新来确立新的竞争优势,是目前各传统运营商普遍面临的课题.电信网络必将由传统电话网络 PSTN发展到以软交换为核心、以分组网为特征的下一代网络 (NGN).NGN是一个非常宽广的概念,具有丰富的内涵,其核心思想是将业务与承载网络分离,这样业务开发就能够独立于网络,从而使新业务的推出更加灵活快捷.NGN预示着电信网络体系结构的一场深刻变革,本文前面部分所讨论的各类新技术其实都是 NGN的组成部分.从传统网络完全过渡到 NGN需要一个较长的过程,而这一过程就是传统运营商的网络不断演进和革新的过程,这一过程与运营商的总体发展战略息息相关,在这一过程中将会涉及到新网络的建设、旧网络的改造以及如何处理两者的关系.