呼损率计算对步进式带宽分配性能的影响

在对电信网虚路径的带宽分配算法的研究中,罗茂松等人提出了一种单虚路径条件下的带宽分配算法,与典型的“二分法”相比,其优点是误差小,运算速度快,其缺点是运行时间起伏波动大。本文在步进式最优算法的基础上,结合计算呼叫损失概率(CBP)的单虚路径近似算法,给出步进式最优带宽分配的快速算法。此快速算法与原有步进式算法相比较,运算速度明显加快,并克服了步进式算法运行时间起伏波动大的缺点。     

On bandwidth adjusted multicast communications in pipeline router architecture

We have developed a novel algorithm to adjust link-bandwidths of a given multicast tree, which sends a message with sizer from a source to a multiple destinations taking into consideration pipelined router. The algorithm that we have developed tries to minimize the end-to-end delay time and resources such as bandwidths of a multicast tree, and performs admirably well in any given multicast tree. Our evaluation shows that the proposed algorithm dramatically reduces the end-to-end delay time and resources reserved to satisfy the time-constraints. This work was supported in parts by BK21 and the Ministry of Information and Communication, Korea. Corresponding author: H. Choo.     

Efficient medium arbitration of FSAN‐compliant GPONs

The steadily rising demand for multimedia and data services, the falling cost and omnipresence of Ethernet and the maturity of passive optical networks (PON) technology, promise to radically change the landscape in the local loop. The heart of a gigabit PON system (recently standardized by FSAN/ITU) is the medium access controller (MAC), which arbitrates access to the upstream link among users with fluctuating traffic demands and effects the multiplexing and concentration policy. At the same time, it has to safeguard the service quality and enforce the parameters agreed in the service level agreements (SLAs) between the users and the service provider. In this paper, a MAC protocol designed to serve any mix of services according to their quality of service (QoS) needs, employing four priority levels along with a high number of logically separate data queues is presented. The architecture and implementation in hardware of a MAC algorithm capable of allocating bandwidth down to a resolution of a byte with QoS differentiation is the focus of this paper. It employs the bandwidth arbitration tools of the FSAN/ITU G.984.3 standard and maps SLA parameters to GPON service parameters to create an efficient, fair and flexible residential access system. Copyright © 2005 John Wiley & Sons, Ltd.     

Design and Implementation of a Cueing Wideband Digital EW Receiver

A cueing wideband digital Electronic Warfare （EW） receiver is presented. The proposed receiver, which is to measure the instantaneous frequency and bandwidth of the intercept short-duration pulse radar signals that cue and match the corresponding ones, meets the requirements of good sensitivity and dynamic range for EW and can save hardware resources greatly as well. In addition, real-time signal processing, which is the main bottleneck for covering a wide instantaneous frequency band for EW receiver, is better solved in the proposed design structure. The highly efficient implementation and good parameter estimation algorithms are proposed as welL Theoretical analysis and experimental results show that this structure is feasible.     

有效提高无线局域网信道可用带宽的MAC机制

802.11 WLAN基础架构BSS（基础服务集）的DCF模式下,有两个因素严重影响可用带宽.一是随着竞争站点数增加,信道竞争开销增大,利用率下降;二是AP（接入点）在竞争信道中并无优势,上下行带宽严重不对称,降低了实际利用率.针对这两个问题提出一种新的MAC机制,首先通过在AP端统计MAC地址来估计竞争站点数,然后根据数学模型计算AP和站点上下行比例控制下的最优初始竞争窗值,通过广播设置以获取信道最大利用率.     

光纤光栅带宽可控调谐装置的研制

当光纤光栅粘贴于非均匀衬底材料中时,其反射谱带宽变化复杂。理论分析了在线性应变场作用下光纤光栅反射谱带宽线性展宽的原理,并利用自行提出的开口环机构及相关机械装置、驱动电路和控制软件,研制出一种新颖的光纤光栅带宽可控调谐装置。该装置测量精度高,实际带宽值与预设值的误差为±0.04 nm,带宽精确可控,最大调谐带宽值达6 nm。另外,该装置重复性好,操作简便,可应用于光纤通信及光纤传感领域。     

Cisco SRP环上的带宽分配

给出了一种较简单的SRP(spatial reuse protocol)加权公平性算法的实现,并在此基础上提出了在Cisco SRP环上进行带宽定量分配的方案.在OPNET仿真环境下对这种带宽分配方案的效果进行了仿真和分析.仿真结果表明这种带宽分配方案具有良好的精确度.     

网络管理中Push机制的研究

随着网络技术的迅速发展，网络管理的重要性在网络建设中变得越来越突出，网络管理协议SNMP也从版本1.0发展到了版本3.0但到目前为止，SNMP协议还主要是一种请求/应答式协议，由于SNMP协议的这个特性，当它被用在大规模网络管理时，就会造成带宽浪费和管理实时性的缺乏，本文针对这个问题，提出一种基于Push技术的解决方案，该方案包括两部分：Push协议操作的设计和Push-MIB的设计，Push协议操作定义了Push-PDU，它用于Push数据的封装；Push-MIB用于Push操作的相关参数的定义，本文提出的Push技术是对传统网络管理协议SNMP协议的很好的扩充，在网络管理中能得到很好的应用。     

DiffServ中AF业务带宽分配公平性

通过在opnet6.0下进行计算机仿真实验及数据分析,研究Diffserv网络中AF业务类间和AF业务类里分别在欠载,过载情况下带宽分配的公平性问题,发现AF类间有较好的公平性,而在AF类里,受RTT,TCP连接数目,非响应流等因素的影响,并没有较好的带宽分配公平性。     

基于校园网带宽利用率最优的视频组播机制

传统的视频点播系统为每个点播用户分配单独的静态通信通道,其系统资源利用率低的缺点使得总体时间段上能并发的点播用户数少。针对网管可控的宽带校园网环境,文章提出了一个采用自适应动态缓存的组播策略,它通过差别服务(Diffserv)比例带宽分配机制保证了一定的视频播送服务质量(QoS),并基于服务端综合调度和客户端回馈的方法动态调整各视频流的播送速度,从而优化了系统整个过程的整体资源利用率,提高了系统的点播性能。