APON的MAC协议设计

本文结合以ＡＴＭ为基础的无源光网络（ＡＰＯＮ）的Ｇ．９８３建议,提出了一种低信元时延变化（ＣＤＮ）、低信元时延（ＣＤ）、无碰撞、公平,高效的媒质接入控制（ＭＡＣ）协议,并对该协议的性能进行了分析。     

ATM网内有信元时延变化

文章介绍了ＡＴＭ网内信元时延变化（ＣＤＶ）的基本定义及其相关的一些概念，着重分析服信元时延变化对于流量控制和业务终端的影响，并从一个固定速率的连接出发给出了两种定义的ＣＤＶ分布的仿真结果，发加深对基本概念的理解。     

ATM SAR处理器发送数据业务的信元调度算法

叙述了ＡＴＭ ＳＡＲ（Ｓｅｇｍｅｎｔａｔｉｏｎ Ａｎｄ Ｒｅａｓｓｅｍｂｌｙ）处理器发送信元的机理,讨论了基于发送调度表的业务成形方式产生的信元时延抖动（Ｃｅｌｌ Ｄｅｌａｙ Ｖａｒｉａｔｉｏｎ,ＣＤＶ）以及信元时延抖动容限（Ｃｅｌｌ Ｄｅｌａｙ Ｖａｒｉａｔｉｏｎ Ｔｏｌｅｒａｎｃｅ,ＣＤＶＴ）,推导了ＣＤＶＴ的计算公式,设计了使最小的信元调度算法ＮＶＳＴ（Ｎｅａｒ Ｖｉｒｔｕａｌ Ｓｄｅｎ Ｔ     

输入缓冲结构ATM交换网络的窗口接入机理研究

本文了输入缓冲结构ＡＴＭ交换网络的窗口接入机理，首先分析了一种传统的相关窗口接入（ＤＷＡ）机理的最大吞吐率性能，然后，提出了一种独立的窗口接入（ＩＷＡ）机理，ＩＷＡ能彻底消除采用传统的ＤＷＡ机理时在输入缓冲器窗口中存在的队头阻塞现象，借助于概率母函数的方法分析了采用该ＩＷＡ机理的输入缓冲ＡＴＭ交换网络的时延和吞吐率性能，给出了求解平均信元时延和最大吞吐率的封闭显式，分析表明，ＩＷＡ机理的性能比传统     

话音ATM交换——一种现实的网络过渡方案

首先介绍了几种基于ＡＴＭ的话音交换方案，重点提出一种６４ｋｂｓ的话音ＡＴＭ交换（ＶＯＡ）的实现模型．该系统包含了传统ＳＴＭ交换与ＡＴＭ交换间的相互转换，并能有效地解决诸如信元打包时延、信元时延抖动，以及系统带宽利用率等关键环节．最后还介绍了有关话音ＡＴＭ交换（ＶＯＡ）技术的其它热点     

基于QOS的无线ATM协议结构及性能分析

有效，合理地分配信道资源和进差错控制是无线ＡＴＭ的两个关键技术，本文提出的基于ＱＯＳ的无线ＡＴＭ协议结构，在信元头加入３６比特的ＢＣＨ码用于差错控制，取代了标准ＡＴＭ信元头的ＶＣＩ／ＶＰＩ；在上行链路的信元头中增加１字节表示排队信息元次序，用于ＭＡＣ控制或信元排序。     

语音业务在ATM网络中降低装配时延提高系统质量的新方法

本文针对ＡＴＭ网络中的语音通信，提出了一种降低信元装配时延的新方法，以及相应的基于ＡＤＰＣＭ的新的信源编码系统，它能确保在信元丢失时，收发双方编译码系统不会失步，并且能产生基本无附加听觉噪声的丢失段恢复语音。文中还分析了各部分参数的求法，实验表明，该法产生的丢失段恢复语音，具有良好的听觉质量。     

ATM网络中恒定比特率和可变比特率语音通信

分析了ＡＴＭ（异步转移模式）网络中恒定比特率（ＣＢＲ）和可变比特率（ＶＢＲ）语音通信方式，讨论了ＩＴＵ－Ｔ１９９７年新颁布的ＡＴＭ可变比特率业务适配标准ＡＡＬ２，给出了信元装配实例。针对ＶＢＲ业务相对ＣＢＲ业务有较大不同的网络传输时延特性，着重分析了语音信号作为ＶＢＲ业务采用ＡＡＬ２适配标准时，通过ＡＴＭ网络传输时的装配时延问题。     

无线异步转移模式(WATM)网络中的差错控制技术

对无线链路中ＡＴＭ信元传输使用的差错控制技术进行了分析，包括无线链路对ＡＴＭ信元头差错控制（ＨＥＣ）和信元定界（ＣＤ）功能的影响，物理层的前向纠错（ＦＥＣ）和交织，应用数据链路自动请求重发（ＡＲＱ）实现可靠的话务传输。分析结果表明，如果采用合理的差错控制方式，尽可能减少射频链路对ＡＴＭ操作的影响，ＡＴＭ传输机制在无线链路中的实现是可行的     

基于ATM高速网介质访问控制方法的研究

本文分析了ＦＤＤＩ，Ｏｒｗｅｌｌ，ＡＴＭＲ，ＣＲＭＡ－Ⅱ，ＭｅｔａＲｉｎｇ等典型的高速网介质访问控制协议，提出了一个新的基于总线时间片的介质访问的控制方法－ＡＴＭＢ，并对ＡＴＭＢ的信元结构，局域网参考模型，控制方法作了进一步研究与分析，该方法基于没有对原网络节点的结构加以改变，它特别适合于高速网络的互连和与大网的转接。     

A lossless handover method for video transmission in mobile ATMnetworks and its subjective quality assessment

Cell loss is one of the major causes of degradation in quality of service in ATM mobile communication systems. It can be suppressed by employing buffer memories in the network; however, cell delay occurs as a consequence. This article proposes a lossless handover method for mobile ATM communication networks that both prevents cell loss and can suppress cell delay variation. The method was simulated on an experimental system to subjectively evaluate MPEG2 images relative to buffer memory size and the results obtained are presented     

The estimation of signaling delay in ATM networks

In multimedia applications over ATM networks, more stringent quality of services are required, because these applications are especially sensitive to the time delay. In this letter, a simple estimation of signaling delay is presented using Erlang service models according to ITU-T “Q.2931”. Additionally, the call blocking probability of a realistic network is considered. The simulation results show that the proposed model can be an effective tool to estimate the setup delay. If the connection setup delay can be effectively estimated according to the network load, then the users may decide whether or not to join this congested network, and thus contributes to the load balance of ATM networks     

Survey of traffic control schemes and protocols in ATM networks

The authors survey a number of important research topics in ATM (asynchronous transfer mode) networks. The topics covered include mathematical modeling of various types of traffic sources, congestion-control and error-control schemes for ATM networks, and priority schemes to support multiple classes of traffic. Standard activity for ATM networks and future research problems in ATM are also presented. It is shown that the cell-arrival process for data sources can be modeled by a simple Poisson process. However, voice sources or video sources require more complex processes because of the correlation among cell arrivals. Due to the effects of high-speed channels, preventive control is more effective in ATM networks than reactive control. Due to the use of optical fibers in ATM networks, the channel error rate is very small. The effects of propagation delay and processing time become significant in such high-speed networks. These fundamental changes trigger the necessity to reexamine the error-control schemes used in existing networks. Due to the diversity of service and performance requirements, the notion of multiple traffic classes is required, and separate control mechanisms should be used according to the traffic classes. The priority scheme is shown to be an effective method to support multiple classes of traffic     

Interaction of call blocking and cell loss in an ATM network

The introduction of broadband ATM networks and services will raise new operational issues. An area of significant challenge to the network operators will be network dimensioning. ATM networks differ from today's STM networks in that they will have to provide acceptable performance with respect to not only call blocking, but also cell loss and cell delay. Consequently, it is important to understand the interaction of call blocking and cell loss/delay in ATM networks. The paper presents a method of exploiting the interaction of call blocking and cell loss performance in order to efficiently operate the ATM networks. Specifically, the paper demonstrates that when the network is dimensioned or engineered to meet an appropriate call blocking objective, the cell loss performance perceived by the accepted calls can be significantly better than the cell loss objective set for the connection admission control (CAC) to admit or deny a call     

A new priority control of ATM output buffer

A new ATM output buffer management strategy with priority control function is proposed, based on four types of cell classes. This strategy can use system resource more effectively, meet the quality of service (QOS) requirements (i.e. cell loss probabilities and delay characteristics) of different services, and also can reduce the complexity of buffer. Furthermore, overload from lower priority traffic doesn't degrade the performance of higher priority traffic (i.e. cell loss rate and cell delay characteristics).     

Applying ATM to mobile infrastructure networks

In response to the explosive increase in the number of mobile subscribers and the ever stronger demand for mobile multimedia services, the authors propose introducing the ATM technique for next-generation mobile network infrastructures in order to handle a high volume of traffic and develop multimedia communications. First, this article clarifies mobile-specific requirements for and advantages of applying ATM to mobile infrastructure networks. However, it is risky for network operators en bloc to replace the conventional STM-based infrastructure by ATM. Therefore, this article shows a smooth evolution path for the mobile network infrastructure to convert from conventional STM to ATM as mobile multimedia services mature. Even in future mobile networks, the main traffic may still be voice communications, whose bit rate is too low for efficient use of the radio frequency band. Applying ATM to such very-low-bit-rate mobile voice streams is inefficient due to the delay in filling out the payload of an ATM cell; this “packetization delay” degrades the quality of service. This problem can be solved by using a layered cell structure for the mobile ATM network. This cell structure enables the efficient transfer of voice signals ranging from very-low-bit-rate signals to high-speed multimedia signals with little delay. Standardization of this cell structure is progressing in ITU-T and the ATM Forum. Transmission efficiency is estimated by simulation     

An ATM queue manager handling multiple delay and loss priorities

The asynchronous transfer mode (ATM) technique has been widely accepted as a flexible and effective scheme to transport various traffic over the future broadband network. To fully utilize network resources while still providing satisfactory quality of service (QOS) to all network users, prioritizing the user's traffic according to their service requirements becomes necessary. During call setup or service provisioning, each service can be assigned a service class determined by a delay priority and a loss priority. A queue manager in ATM network nodes will schedule ATM cells departing and discarding sequence based on their delay and loss priorities. Most queue management schemes proposed so far only consider either one of these two priority types. The queue manager handles multiple delay and loss priorities simultaneously. Moreover, a cell discarding strategy, called push-out, that allows the buffer to be completely shared by all service classes, has been adopted in the queue manager. We propose a practical architecture to implement the queue manager by using available VLSI sequencer chips     

话音ATM交换(VOA)──一种现实的网络过渡方案

ATM作为未来B－ISDN的交换方式，具有大容量、综合化及带宽经济的优点，因此64kb／s的话音ATM交换（VOA）技术必将成为现有窄带通信网向未来宽带综合网过渡有效的解决方案之一。本文首先介绍几种基于ATM的话音交换方案，重点将着眼于提出一种64kb／s的话音ATM交换（VOA）的实现模型，该系统包含了传统STM交换与ATM交换间的相互转换，并能有效地解决诸如信元打包时延、信元时延抖动、以及系统带宽利用率等关键环节，本文的最后还将介绍有关话音ATM交换（VOA）技术的其它热点。     

业务穿越ATM-PON的延时和延时变化研究

ATM-PON是光纤接入网的重要技术。文章研究了业务穿越ATM-PON接入网的延时和延时变化性能，着重分析媒体接入控制协议对业务延时和延时变化性能的影响。研究结论对ATM-PON媒体接入控制协议的合理设计有很大的帮助。     

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.