突发业务环境下CBR业务性能的实验分析

ＣＢＲ业务是一类极为重要的实时业务,能否有效地传递这类业务关系到从现有网络向ＡＴＭ的过渡,因此ＣＢＲ业务的服务质量是一个值得研究的重要课题,本文利用计算机仿真的方法,全面地分析了突发业务环境下,影响ＣＢＲ业务服务质量的各种因素,指出复接器占有率,缓冲区容量,背景强度,背景流的自相关物征对ＣＢＲ业务的是延及时抖动有很大的影响,尤其是背景流具有长时相关性时,ＣＢＲ业务是服务质量将严重恶化,必须设法加以     

短消息业务时延分析

本文对于短消息业务中的各个环节对短信时延的影响进行了比较深入的研究,综合分析了短消息业务时延分布规律。     

MS-OTN网络不同业务类型的时延比较研究

近几年“时延（Delay/Latency）”已逐步成为一个重要的传输指标,“低时延”是高品质传输专线的典型需求之一。MS-OTN(Multi-Service Optical Transport Network)网络利用其丰富的开销字节,强大的网络能力和传输速率,能为2Mbps～100Gbps的不同业务类型所承载的高精品用户专线、云间互联、5G等新型业务提供服务。文章通过对MS-OTN网络不同业务封装类型的测试分析比较了各业务封装类型对于时延的影响,进而分析OTN时延影响关键因素,并结合网络部署情况,为各类需求提供出合理的业务选型方案。     

浅谈电信业务的误码和时延指标

业务量要求和服务质量要求是对网络的基本要求。业务量要求对数据如何在网络上传送加以规范,同时对传送业务所需的网络资源加以规范。应用数据包在网络上传送时会遇到时延和潜在误码的影响,时延要求和误码率要求就是服务质量(QoS)要求。我们针对应用层和网络层分别探讨不同的应用对服务质量的要求,如表1所示。应用层面服务质量用应用数据元(ADU)的时延和误码率来表达,网络层面服务质量用包数据元(PDU)的时延和误码率来表述。时延要求针对实时流媒体和块传送应用,分为绝对时延和时延变量两个指标。表1　　不同的应用对应用层和网络层的服…     

多媒体通信中不同优先级的业务复用模型分析

本文建立了基于流体流方法的复用模型，分析了具有不同优先级的多业务复用情况，计算了平均时延、平均队长及分组丢失率等服务质量参数，比较了有无优先机制时上述服务质量参数的异同。     

TDMA时隙分配对业务时延性能的影响分析

 在TDMA通信系统中,时隙分配是影响业务时延性能的重要因素,包括时隙数量分配(带宽分配)、时隙分配周期(TDMA帧长)和时隙位置分配三方面.本文针对可变速率和固定速率两类业务,基于随机服务系统理论和交通流理论建立了业务时延模型,得到了平均时延的解析式,分析了时隙数量、时隙位置和TDMA帧长度对业务时延影响的规律和特点.结果表明时隙位置分配越均匀,越能改善业务的平均时延和时延抖动性能;而在传统的时隙连续分配方式下,增加时隙数量分配对时延性能提高非常有限.在DVB-RCS卫星系统等具有较长帧设计的TDMA系统中,采用时隙均匀分配方式能够有效提高业务时延性能.计算机仿真验证了建模分析的正确性.     

HSPA业务建立时延优化

结合现网中的优化案例，介绍了几种典型场景下优化RRC建立时延、RAB指配时延、寻呼响应时延、小流量业务建立时延的方法，优化效果表明，以上方法在降低业务建立时延上有一定效果。     

HSPA网络业务建立时延研究

以厦门HSPA网络为对象,利用多种数据源重点分析了业务建立过程中RRC和RAB建立阶段的时延,定位了影响时延的终端类型、业务类型、组网策略、信令流程设置等因素,并结合DT测试数据评估了现网业务建立总时延及端到端建立时延.     

移动网络上的流媒体业务

在移动网络上开展流媒体业务，最大的问题是无线环境的时变性容易引起丢包时延，导致缓冲过多、图像质量差和播放中断。因此，应使流媒体系统根据网络带宽的变化．适当调整服务器传送的音视频流。介绍了相应的关键帧技术和动态多码率技术，以及在终端上实现无线流媒体业务的整个流程。     

面向5G URLLC业务的时延分析与无线超低时延技术研究

5G面向三大场景业务,其中URLLC业务的低时延高可靠特性为无线网络带来了新的挑战.无线空口侧时延主要受传输间隔、资源调度、混合重传、终端和基站处理时延等因素影响.为解决时延问题,3GPP R15标准中已从减少传输时间间隔和优化资源调度两个方向提出了低时延技术,满足5G网络部署初期的低时延业务需求.     

Priority assignment control of ATM line buffers with multiple QOSclasses

In an asynchronous transfer mode (ATM) network multimedia environment, the bandwidth efficiency can be improved by defining multiple quality of service (QOS) classes and using a traffic control which manages required QOS of each class individually (QOS control). Priority assignment control is presented as a QOS control method in an ATM switching node. To quantitatively evaluate the control performance, the region determined by the offered load of each class where the QOS requirements of all the classes are satisfied is analytically obtained and various combinations of two classes and related control effects are discussed. When required values of cell loss rate and delay time are both different between the classes, the control effect is large; however, when only either of them is different, the effect is relatively small. The control scheme to enlarge the actual admissible offer load region by adaptively changing the priority assignment ratio is presented and its feasibility is confirmed by the simulation     

Evolution and service requirements of CBR applications on ATM networks

Broadband integrated networks based on asynchronous transfer mode (ATM) technology are being proposed to provide a single integrated access to a variety of services and applications. Constant bit rate services will form an important part of this unified networking solution. In this paper, we identify and describe the relevant aspects related to the implementation of CBR services on ATM. First, we identify two broad categories of potential CBR services for broadband ATM networks. The ATM infrastructure for the identified services is then developed along with the required functionalities of different network elements. Finally, end-to-end performance objectives for the ATM network are determined and verified empirically based on results of laboratory experiments. These performance objectives help us determine the minimum QOS required by the highest class of service category offered by an ATM network.     

ATM DQDB城域网中恒定比特率业务的性能（Ⅱ）;延时分析

本文分析了ＡＴＭ ＤＱＤＢ城域网中恒定比特率业务的时延特性，恒定比特率业务比可变化特率数据业务的优先级高，但两者都采用统一的分组方式进行传输。本文的分析表明，在业务负荷不是非常重的情况下，恒定比特率业务的时延性能还是令人满意的，从而说明了ＡＴＭ ＤＱＤＢ城域网的可行性。     

PERFORMANCE ANALYSIS FOR ATM SWITCHING OF MIXED CONTINUOUS-BIT-RATE AND BURSTY TRAFFIC WITH SMOOTHING FUNCTION

Traditional packet switching networks have typically employed window-based congestion control schemes in order to regulate traffic flow. In ATM networks, the high speed of the communication links and the varied nature of the carried traffic make such schemes inappropriate. Therefore, simpler and more efficient schemes have to be proposed to improve the congestion control for ATM switching. This paper presents an exact performance analysis of ATM switching whose inputs consist of Continuous-Bit-Rate(CBR) and bursty traffic. The CBR traffic and bursty traffic are described by Bernoulli process and the Interrupted Bernoulli Process(IBP), respectively. Bursty traffic smoothing mechanism is analyzed. With the use of a recursive algorithm, the cell loss probability and the average delay for ATM switching of mixed CBR and bursty traffic are exactly calculated. Traffic smoothing could be implemented at a slower peak rate keeping the average rate constant or decreasing the average bursty length. Both numerical a     

Traffic management for B-ISDN services

A set of asynchronous transfer mode (ATM) bearer service categories, differentiated in terms of quality of service (QOS), that will support the large spectrum of applications expected in broadband integrated services digital networks (B-ISDN) is defined. The evolution of applications and the traffic requirements in B-ISDN/ATM networks are described, and the evolution of network services to address these requirements is discussed. The definition of ATM bearer service categories necessary for the economical support of initial applications and evolution to future B-ISDN services is proposed. The elements of the ATM traffic management strategy to support these service categories are presented     

Worst-case fraction of CBR teletraffic unpunctual due tostatistical multiplexing

This paper quantitatively analyzes the queueing delay of the constant-bit-rate (CBR) traffic in a multiplexer, where the CBR traffic is mixed with the traffic of another session (interfering traffic) that has throughput and burstiness constraints. This paper focuses as a quality-of-service (QoS) measure on the fraction of the CBR traffic that fails to meet a certain delay requirement. Results include the worst-case QoS of CBR traffic as a function of the throughput and burstiness parameters imposed on the interfering traffic. Results of this paper can be applied to traffic management and call processing of asynchronous transfer mode (ATM) networks     

PERFORMANCE ANALYSIS OF TRAFFIC CONTROL METHODS ON MIXED TRAFFIC CLASSES IN ATM LAN

We treat traffic control methods for the multimedia ATM LAN, in which two service classes are considered; one is for high-speed data transfer based on a fast reservation protocol (FRP service class) and the other is for the continuous bit rate (CBR) traffic such as motion video (CBR service class). Through an analytic method, the performance of the CBR service class traffic is shown to be heavily affected by the FRP service class traffic. Thus, we introduce a reserved bandwidth for the CBR service class to guarantee some appropriate level of performance for the CBR service class. With the reserved bandwidth for CBR service class, the performance of CBR service class can be preserved from being affected by the FRP class traffic load.     

无线ATM通信网的定时信息恢复技术研究

本文对无线ＡＴＭ通信网ＣＢＲ业务定时信息的恢复技术进行了研究，提出了异步剩余时间标签（ＡＲＴＳ）技术，并通过码速调整改善收端的ＣＢＲ业务时钟性能，给出了实现方案，同时提出采用ＡＲＴＳＦＩＦＯ吸收定时信息的延时抖动，由于无线ＡＴＭ通信网的误码率较大，其信元丢失率较高，本文在分析ＲＴＳ的多重码速调整特性基础上，还提出了利用收到相邻ＡＲＴＳ之间的差值规律来估计丢失的ＡＲＴＳ的新方法，理论计算和模拟结果表     

ATM网络中CBR业务排队性能分析

分析了ATM网络中CBR业务排队性能,给出了一种简单的计算信元丢失率和信元平均时延的表达式.分析结果表明,一方面在较小的缓冲区容量下,即使CBR业务被分配的带宽大于等于其峰值速率,也还存在着较大的信元丢失;另一方面,当复用的CBR业务源数目很大时,只需要分配相对较小的缓冲区容量就可以满足十分低的信元丢失率要求.该结果对于ATM设备中相应的缓冲区设计、带宽分配以及连接允许控制机制的研究具有重要的意义.     

Transport of IP controlled-load service over ATM networks

A hot topic in the research community is the interworking of integrated IP services, defined by the IETF, with ATM, a technology designed for the transport of multimedia traffic. In particular, the IETF recommends the ATM CBR, nrt-VBR, and ABR service classes for the transport of controlled-load service (CLS) over ATM. In this work the first two alternatives are examined and compared, in order to determine which is the most convenient for CLS. The comparison is carried out in terms of QoS and amount of buffering required at the IP/ATM routers. These performance parameters strongly depend on the parameters of the CLS token bucket shaper, that is, the token bucket depth and token bucket input buffer capacity. A nrt-VBR connection is able to offer a given performance level over a range of values of the token bucket parameters wider than that permitted by a CBR connection. Moreover, in all the examined cases the nrt-VBR connection needs a relatively small ATM buffer at the IP/ATM routers. Since, in order to guarantee acceptable performance, some CLS requests must be rejected, the utilization of the ATM link can be relatively low; this drawback can be overcome by serving the rejected CLS requests as classic best-effort traffic