令牌网络中非对称性问题研究

本文采用嵌入马尔可夫链理论和概率母函数的方法，根据循环查询时间变量的二阶特性，在离散时间状态下对非对称性令牌网络进行了分析，给出了一种报文分组平均等待时间的近似解析式，同时也给出了计算机模拟实验结果。     

容错型令牌总线网性能评价算法

本文对符合ＩＥＥＥ８０２．４和ＭＡＰ标准的令牌总线网的性能指标评估给出了一种新的计算方法。文中重点考虑了具有信包重发机制、令牌最大保留时间和信包缓冲区容量有限的令牌网络的性能指标评估问题，克服了以往不能分析同时具有信包重发机制和令牌最大保留时间令牌网性能的局限。文中给出的方法简单易行、计算迅速、精度颇高。最后，本文通过例题说明了此方法的应用。     

线性令牌网络消息延时的自适应控制

针对线性令牌网络上不同优先权的消息延时不同,提出了一种自适应控制网络消息延时的算法。计算机模拟结果表明在网络负载为时变非对称的条件下,该算法可以自适应的调节各优先权的令牌循环时间,使线性令牌网络为各优先权提供公平的优先级服务。同时,还对控制算法中滑动时间窗口的选择进行了详细讨论。     

噪声环境中采用探询机制的局域网性能分析

轮叫探询机制已被应用于实时控制网络。本文根据发布／预定接收型通信模型，针对噪声环境，建立了该机制的令牌传送状态机，探讨了在集簇噪声影响下令牌传送的详细过程，并出轮叫探询机制的平均令牌传送时间和平均令牌循环时间，通过它们的解析表达式分析了噪声对网络性能的影响。     

容错型令牌总线局域网建模及性能指标评估

本文对符合ＩＥＥＥ８０２．４标准的容错型令牌总线局域网给出了其Ｐｅｔｒｉ网建模及性能指标评估方法。文中考虑了具有信包重发机制、令牌最大保留时间和信包缓冲区容量有限的令牌网络的性能指标评估问题，克服了以往不能分析具有信包重发机制和令牌最大保留留时间等令牌网性能的局限。本文讨论了带计数禁止弧的确定性时延随机Ｐｅｔｒｉ网（ＤＳＰＮ）的特性，并对给出的ＤＳＰＮ模型进行了仿真计算，对影响网络性能的系统指标进     

线性令牌传递网络中消息实时保证概率分析

本文针对线性令牌传递网络,提出了一种网络带宽分配方法和基于实时保证概率的网络性能分析方法,导出了消息严格实是的保证概率表达式,并给出了实用的近似算法。     

令牌环形系统的伪守恒定理及性能研究

利用循环服务系统的循守恒定律，导出了批泊松到这令牌环形网络在发尽式、限制式服务规则情况下平均等待时间加权和的表达式。讨论了边界条件，由此得出了具有上述相同服务规则的对称性环形网络平均等待时间的精确表达式．     

工业智能令牌网的实现

介绍了ＭＣＳ系列ＣＰＵ用于多机通讯时，组成智能令牌网，适应工业现场的需要。介绍了令牌的传递方式和实施方案及应用范围。它是一种很有前途的工业现场信息传递方式。是一种实用的工业网络。     

一种多信道的分簇式短波令牌协议

传统的短波令牌协议( HFTP)调度方式单一,在没有数据传送时,信道资源会被各节点间的令牌传递所占用,且令牌在通信质量较差时易丢失。基于此,提出一种多信道的分簇式短波令牌协议( CHFTP),通过以通信质量评估为标准的分簇算法和基于预约的动态令牌调度,减小了令牌丢失的概率和令牌传递、处理的开销,并给出了仿真分析。仿真结果表明,该协议的端到端平均时延和网络吞吐量明显优于短波令牌协议, CHFTP 的平均时延最多可减少75%,网络吞吐量最多可增加66.7%,适合在短波通信网络中使用。     

基于令牌漏桶法的数据记录技术

针对实时系统记录数据会引起系统运行速度缓慢、瘫痪、甚至＂死机＂的问题,提出了具有特色的令牌漏桶法。该方法通过创建循环队列数据池并根据数据池的数据量适时发放令牌和拥有令牌的任务自动选择CPU空闲时执行等技术实现。通过试验验证,在保证整个系统实时性、可靠性的前提下,该方法实现了实时记录数据的功能。     

Performance and parameter region for real-time use in IEEE 802.4token bus network

The upper and lower bounds for the mean cycle time and the mean message transmission time of class six and class four in the IEEE 802.4 token bus network, within which the minimum utilization constraint of class four is guaranteed, are derived. Stability conditions for the token bus network are also derived. These bounds and stability conditions are represented in terms of the high-priority token hold time, the token rotation time, the arrival rate, the total number of stations, etc. A parameter-tuning algorithm in a partially symmetric token bus network with two classes is suggested. This algorithm maximizes the utilization of class four for a given high-priority token hold time and at the same time meets the constraints of the stability condition of the network, the real-time constraint, and the minimum utilization of class four     

Setting target rotation times in an IEEE token bus network

The IEEE standard 802.4 token bus protocol requires each network station to implement a synchronous (highest priority) message class, and permits a station to implement three lower priority classes: urgent asynchronous, normal asynchronous, and time available. Each of the lower three priorities (called access classes) is assigned a target token rotation time that limits the amount of time that a station can use to service lower priority traffic. A formulation of the problem is presented in which messages are transmitted from an access class as long as network throughput remains below a user-specified threshold. Formulas are derived that transform this priority scheme, based on network throughput limits, into the proper target rotation time settings that the token bus protocol actually requires. The analytical model is compared with a computer simulation of the token bus protocol and shows close agreement     

Throughput analysis of the IEEE 802.4 priority scheme

The IEEE 802.4 token bus standard defines an optional priority scheme to handle multiple classes of data. It allocates the channel bandwidth among different priority classes of messages by a set of timers at each station. An analytical model for the priority scheme is presented. The model relates the throughput of each priority class of messages to the traffic intensities of different classes, the target rotation times, and the high-priority token holding time. The network is assumed to be symmetric with respect to its parameters and the traffic distribution among nodes. Simulation results are used to evaluate the accuracy of the model. The model provides means of evaluating the network throughput and can be used to determine the time values to meet the throughput requirements of different classes of traffic     

Selection of timed token protocol parameters to guarantee messagedeadlines

Networks that use the timed token protocol (such as the 100 Mbit/s FDDI network) are well suited for real-time applications because they guarantee, to each node, an average bandwidth and a bounded access time to the communication network. This guarantee is necessary but not sufficient for the timely delivery of deadline-constrained messages; protocol parameters must be carefully selected to ensure that these messages meet their deadlines. This paper addresses the issue of selecting the protocol parameters TTRT (target token rotation time) and the synchronous capacities assigned to each node. The objective is to guarantee that each synchronous message is transmitted before its deadline. An upper bound is derived on the worst case achievable utilization (WCAU) of any parameter selection scheme. The WCAU of a scheme is defined as the maximum utilization U such that the scheme guarantees all synchronous messages as long as their utilization is less than U. An algorithm for selecting the above parameters is proposed, The algorithm is shown to have a WCAU that is very close to the upper bound     

分布式实时通信网络在火控系统中的应用

通过对现代雷达火控系统通信基本特点的分析，提出一种适合于现代雷达火控系统的通信方式——基于ARCNET的多总线拓扑强容错令牌总线网，并对实时系统与实时通信的特征作了深入的分析。     

DYNAMICALLY VARYING THE TOKEN ROTATION TIME LIMIT OF A TOKEN PASSING NETWORK

This paper presents a performance study for a class of token passing networks which allow the token rotation time (TRT) limit to be adjusted dynamically in accordance with the type of delay-sensitive sessions in progress. Results show that the dynamic scheme allows higher throughput to be attained compared to a static scheme, under most circumstances. However, when the switching overheads are comparable to cycle latency, the frequent establishment and tearing down of delay-sensitive sessions may cause excessive adjustments and result in lower throughput.     

Performance of token schemes supporting delay-constrained prioritytraffic streams

A symmetric priority-based token network is considered. Messages are divided into two priority classes. High-priority messages are assumed to require tight delay constraints. As a result, each station is allowed to establish, at any time, at most a single real-time high-priority access concentration. High-priority messages are guaranteed access onto the channel within a prescribed limited period. In turn, regular priority messages are only served when the system determines, through the repetitive use of circulating tokens (as used by the IEEE 802.5 token-ring-type protocol), that no high-priority messages are currently waiting in the system. Two token schemes employing different service disciplines are used to provide network access. Exact and approximate mean delay formulas for both message classes are derived. Numerical results are then exhibited to illustrate the network performance under various traffic conditions     

基于令牌总线网络的RS 485应用

应用RS 485物理层标准,构建总线型的控制网络,采用令牌方式实现总线的共享访问,以适应控制网络实时性要求。在进行令牌总线协议设计时,从RS 485特点出发,以特殊的设计来简化协议,提高协议的效率。为了保证网络的可靠性,在协议中采用了有效的错误处理方法,即保证数据传输的正确性,又减小了协议的控制开销,以简单、方便、快捷、高效的方式实现控制网络的介质访问管理,给RS 485网络提供一种较好的连网模型。