重心法在传输机房选址中的应用

传输节点机房(以下简称"节点机房")作为通信网络最基础的物理节点,是各运营商重要的战略储备资源。除了节点机房的数量、机房稳定性、机房空间等要素外,节点机房的科学分布也对网络的科学性、稳定性、扩展性等方面起着至关重要的作用。本文提出的重心法可以更加科学地指导运营商在工程实际中进行机房选址。     

全业务城域网 汇聚节点机房建设解读

作为传输网络基本要素之一的传输节点机房,是传输网络中最基础的物理节点,也是各运营商重要的战略储备资源,必将成为一段时间内通信网络建设工程中的重中之重。     

CDN边缘节点部署位置下沉的研究

CDN的出现,把流量推到网络的边缘,缓解主干网络的拥堵。当前CDN运营商的主要部署节点是在IDC机房,在通信运营商看来,IDC到最终用户还隔着CMNET,核心网与传送网。随着手机、平板等无线设备的普及,给核心网带宽压力越来越大。将CDN边缘节点下层到核心网中,对缓解核心网的网络压力,降低网络时延有着巨大的作用。本文对CDN边缘节点下沉的可行型及方案进行了分析,并特别针对当前研究比较少的CDN边缘计算节点进行了分析,由于缓存系统与CDN已渐成融合的趋势,本文将缓存系统的节点视为CDN边缘节点。     

浅析C-RAN机房选址偏离对于传输的影响

为配合5G网络建设,各运营商C-RAN信源机房都在紧锣密鼓地规划和部署。C-RAN机房数量多、投资大、集中的信源设备多,一旦部署投产,后期调整代价大。本文从C-RAN机房选址偏离成因、偏离对前传影响、偏离对传输安全性影响等方面展开论证,从传输角度给C-RAN机房选址提供了积极的参考意见。     

无线宏基站选址方法研究

智能手机及通信网络的发展,当前宏基站建设也在不断的趋近无线化,随着4G网络的普及,网络部署及市场先机的抢占成为了当前各大运营商网络建设的关键。而由于机房面积、条件等限制很多的基站不得不重新进行选址建设,同样选址还会对后续的施工等产生一定的影响,本文从宏基站建设过程中机房、天面及物理位置的选取来综合性的开展研究。     

5G接入机房选址流程优化策略研究

深圳作为5G网络建设起步较早的城市之一,已立项、规划并部署了一批5G接入机房。因管线建设困难等原因,部分机房在选址后无法投产使用,需进行退址、退租并启动重新选址流程,对运营商的选址效率和建设成本有一定影响。系统整理深圳5G一期工程中5G接入机房的主要退址原因,针对性地提出选址流程优化策略,对后续5G机房选址具有一定的借鉴和参考意义。     

深圳国际会展中心5G业务汇聚机房设计难点及策略分析

因公共建筑使用周期较长,运营期间难以维护修缮,在建设过程中普遍采用设计阶段的先进通信技术以保障使用寿命.5G业务汇聚机房因其具备传输和无线专业的重要节点属性,高效率建设并支撑各专业需求是机房建设的重要课题.实际机房选址和建设过程中,往往存在不少难以预估的制约.以深圳国际会展中心为例,分析运营商建设5G业务汇聚机房的设计...     

面向未来的汇聚机房建设研究

汇聚机房在电信网中是电信网承上启下的关键,是运营商业务开展的阵地。针对汇聚机房目前暴露的总量少、自有率低、空间不足、可用性差等问题,运营商应着眼干线扁平化、网络重构、5G商用、更高清业务发展的需要,在重要汇聚、普通汇聚、业务汇聚差异化定位的基础上,对汇聚机房进行选址和配套建设,以确保电信网的长久发展。     

基于覆盖条件下的GSM/WCDMA共址组网可行性分析

对于电信运营商而言,基站进小区选址的难度已远远大于2G建网之时,而有关运营商已有庞大的GSM网络,能否利用现有的2G站址和机房,实现机房、站址、传输资源共享,是电信运营商面临的主要现实问题之一。本文基于GSM／WCDMA技术特点,以密集城区为例通过2种方式对GSM和WCDMA网络的覆盖进行分析,探讨了海南联通GSM和WCDMA基站共址的可行性。     

新型有源机房式地箱组建广播电视网络的方案与分析

旧机房空间不够,新机房选址困难、建设难度大,建设周期长,郊区的新楼盘离机房距离远,如何低成本快速提供高带宽的双向网络是运营商共同关心的问题。根据广州有线电视的经验,介绍有源机房式地箱与CCMTS相结合的建设方案,可快速搭建网络,提供高带宽的互动高清电视业务和宽带业务。     

大规模输电线路状态监测传感器网络的周期性低功耗通信技术方案

为了实现输电线路监测的功耗低、寿命长、绿色发展的目的，提出大规模输电线路状态监测传感器网络周期性低功耗通信技术方案。依据网络中传感器网络组网特征以及节点运行状态转换特点，设置睡眠定时器，以周期性运行方式使传感器网络通信节点在初始化、睡眠、激活状态间转换，通信节点在输电线路状态监测数据无传递需求时进入睡眠状态，节省通信功耗；传感器网络汇聚（sink）节点利用梯度创建上行路由，通过源路由的方式创建下行路由，以跳数和剩余能量为依据进行上、下行路由数据分组传递，降低节点功耗，延长通信运行时间。实验显示，大规模输电线路状态监测传感器网络应用该技术方案后，通信功耗明显降低，运行时间明显延长，且不会影响监测传感器网络的数据传输性能，延长了监测传感器网络的使用寿命。     

Improved multicast routing in MANETs using link stability and route stability

The growing popularity of multimedia applications and services needs to support several quality of service metrics such as high throughput, low energy, and jitter, which is a challenging task in mobile ad hoc networks. Because of limited bandwidth, energy constraints, dynamic topology, transmission errors, and fluctuating link stability, the links between adjacent nodes are often not reliable and may break because of node mobility. Link breakage initiates the process of rerouting either at the sender node (the node at which the link breaks) or at the source node. In either case, it leads to packet loss, delivery delays, and increased control overheads. Hence, to attain a minimum quality of service, routing protocols must address the dynamic network topology. Uncertain and varying movement of nodes necessitates stability of the links between such nodes. The objective of this paper is to propose 2 protocols, the first based on link stability and the other based on route stability. Link stability identifies a stable link from the available links to the next hop and determines a stable end‐to‐end route. The probability of successful transmission of periodic packets is used as a link stability metric to assess the stable path. Acknowledgment ‐free packets are used to check connectivity in the network. Increased probability of successful transmission implies that the selected link is sustained for longer duration and can deliver packets more reliably or, as a consequence, results in a stable link to deliver a better data rate. With a stable link, there is a reduced possibility of retransmissions, reduced end‐to‐end delay, reduced control overheads, and enhanced data delivery ratio. Selection of the most stable route for data transmission improves the performance. Experimental results from simulations performed on EXata/Cyber v2.0 simulator reveal that our proposed protocols are an improvement over the existing protocols in terms of packet delivery ratio, average end‐to‐end delay, and average route lifetime, even without route optimization with the minor increase in control packets. A case study of the application of proposed protocols is also presented.     

传感网中多路径Sink节点隐私保护方案的改进

针对原方案中第一个交叉结点发送假包而不考虑该节点处真实数据流量的问题,提出在第一个交叉结点处进行流量监控,并根据监控的真实数据流量值来决定发往每个假的Sink节点的假包量的方案,并且假包概率传输的同时,当假包传输跳数大于真实数据包到达Sink节点跳数时,就自动丢弃。实验结果表明,网络数据传输的安全时间有了明显提高,但是需要牺牲少许网络能量开销。     

一种面向高速路车联网场景的自适应路由方法

车载自组织网络中节点的高速移动性使得网络拓扑频繁变化,造成路由效率低下.本文提出了一种面向高速路车联网场景的自适应路由方法.本方法采用了贪婪机会转发（GOF）算法,在选择下一跳转发节点时,同时考虑到目的节点的距离计算、节点间的链路状态以及下一跳的有效节点度状况来找出最优转发节点,并提出新的计算连通概率的方法.仿真实验和实际道路场景的测试表明,与相关算法相比在路由稳定性方面表现出较好的效果.     

A novel residual energy‐based distributed clustering and routing approach for performance study of wireless sensor network

Non‐uniform energy consumption during operation of a cluster‐based routing protocol for large‐scale wireless sensor networks (WSN) is major area of concern. Unbalanced energy consumption in the wireless network results in early node death and reduces the network lifetime. This is because nodes near the sink are overloaded in terms of data traffic compared with the far away nodes resulting in node deaths. In this work, a novel residual energy–based distributed clustering and routing (REDCR) protocol has been proposed, which allows multi‐hop communication based on cuckoo‐search (CS) algorithm and low‐energy adaptive‐clustering–hierarchy (LEACH) protocol. LEACH protocol allows choice of possible cluster heads by rotation at every round of data transmission by a newly developed objective function based on residual energy of the nodes. The information about the location and energy of the nodes is forwarded to the sink node where CS algorithm is implemented to choose optimal number of cluster heads and their positions in the network. This approach helps in uniform distribution of the cluster heads throughout the network and enhances the network stability. Several case studies have been performed by varying the position of the base stations and by changing the number of nodes in the area of application. The proposed REDCR protocol shows significant improvement by an average of 15% for network throughput, 25% for network scalability, 30% for network stability, 33% for residual energy conservation, and 60% for network lifetime proving this approach to be more acceptable one in near future.     

Smoothing variable-bit-rate video in an internetwork

The burstiness of compressed video complicates the provisioning of network resources for emerging multimedia services. For stored video applications, the server can smooth the variable-bit-rate stream by transmitting frames into the client playback buffer in advance of each burst. Drawing on prior knowledge of the frame lengths and client buffer size, such bandwidth-smoothing techniques can minimize the peak and variability of the rate requirements while avoiding underflow and overflow of the playback buffer. However, in an internetworking environment, a single service provider typically does not control the entire path from the stored-video server to the client buffer. This paper presents efficient techniques for transmitting variable-bit-rate video across a portion of the route, from an ingress node to an egress node. We develop efficient techniques for minimizing the network bandwidth requirements by characterizing how the peak transmission rate varies as a function of the playback delay and the buffer allocation at the two nodes. We present an efficient algorithm for minimizing both the playback delay and the buffer allocation, subject to a constraint on the peak transmission rate. We then describe how to compute an optimal transmission schedule for a sequence of nodes by solving a collection of independent single-link problems, and show that the optimal resource allocation places all buffers at the ingress and egress nodes. Experiments with motion-JPEG and MPEG traces show the interplay between buffer space, playback delay, and bandwidth requirements for a collection of full-length video traces     

一种基于LEACH的改进分簇路由协议

经典LEACH算法在每轮数据传输过程中,所有子节点均向汇聚节点传输数据,成员节点充当簇头次数不均匀,导致信息冗余与节点能量浪费,使网络生存时间变短。针对这一问题,提出了一种基于部分成员节点随机转发机制的分簇算法,让子节点在数据传输过程中,按照均匀分布规律,选择部分节点工作。仿真结果显示,与经典的LEACH算法相比,改进后的协议延长了约38%的网络寿命,推迟了第一节点死亡时间约13%,大大地降低了能耗。在大规模网络仿真方面,优势更明显。     

链路守卫节点合作监测检测恶意合谋攻击

针对移动Ad Hoc网络环境中合谋节点的恶意丢包行为,将源节点及其传输链路上各守卫节点所检测的结果结合起来,设计一种通过守卫节点合作监测来检测发现恶意合谋攻击的方法.NS2上仿真实验结果表明,该方法能够有效应对合谋节点的恶意丢包行为,降低恶意路由出现的概率,提高网络的分组投递率.     

A service level model and Internet mobility monitor

Mobility is gaining a tremendous interest among Internet users and wireless access networks are increasingly being installed to enable mobile usage. Internet mobility requires solutions to move between access networks with maintained network connectivity. Seamless mobility in turn means that the experience of using a service is unaffected while being mobile. Communication in next generation networks will use multiple access technologies, creating a heterogeneous network environment. Further, roaming between network service providers may take place. To enable mobile nodes to move between access networks within as well as between network service providers with minimal disruption, nodes should be able to maintain multiple active network connections. With the usage of multihomed nodes, seamless mobility can be achieved in already installed infrastructures, not providing mobility support. Mobility in heterogeneous access networks also requires network selections that scale for services. In this article we propose an architecture where application service providers and network service providers define service levels to be used by a mobile node and its user. The user selects a service and the service level from an application service provider. When performing access network selection, information received as part of an application service level will be used to find a network that supports the service required. The performance of available access networks will be monitored and considered when making the decision. Our proposed architecture provides solutions to move flows between interfaces in real-time based on network performance, quality of service signalling to correspondent nodes, and cancellation of flows to give way for more important traffic.     

一种快速低开销的移动节点分布式寻路RPL路由协议

针对低功耗有损网络(Low Power and Lossy Network, LLN)中移动节点作为中继节点时,存在无线链路易断开、数据传输成功率较低和控制开销较高的问题,提出了一种快速低开销的移动节点分布式寻路RPL路由协议(Mobile Node Distributed Pathfinding RPL Routing Protocol, MNA-RPL)。首先,提出一种邻居表自适应更新机制,依据邻居表快速切换父节点;其次,提出一种父子节点双断开机制,能够有效减少数据包丢失;最后,提出一种基于速度动态管理的Trickle计时器,根据自身速度动态调整DIO广播周期。理论分析和仿真结果表明,与主流路由协议相比,该协议在数据传输和控制开销等方面的性能均有一定的提升。