Wishbone总线交易级建模

交易级建模在系统功能建模和验证方面可以增快速度,也可以加速仿真的速度并允许在高层次抽象中研究和确认设计中可供选择的模块.针对Wishbone片上总线协议,依据SystemC中接口方法调用的基本原理和交易级建模的方法,完成了Wishbone总线中共享总线的交易级建模,结果表明SystemC适合在交易级建模系统的行为和通信,交易级建模在仿真速度方面具有优势.     

应用SystemC的AMBA总线系统级模型的设计与实现

对SystemC进行系统级通信结构建模的语言元素进行了深入的研究,并以一个基于AMBA总线的典型SoC为例进行了通信结构的建模.从设计的顶层开始,应用SystemC语言提供的建模能力,采用通信结构细化方法对系统级总线模块进行了细化,针对设计流程中需要将系统级模型转换为可综合的RTL级模型的问题,给出了将系统级总线通信模块转换为SystemCRTL模型的解决方法.由此,建立了完整的应用SystemC的系统级通信结构的建模方法.     

面向卫星移动通信的系统级仿真平台设计与实现

针对卫星移动通信系统中对组网架构、协议体制和关键技术进行仿真论证的需求,设计了系统级仿真平台。首先介绍了系统级仿真平台架构,然后结合架构分析仿真平台的配置管理模型,对卫星、终端、信关站等核心通信节点进行建模,研究仿真平台工作流程,最后,通过多用户并发模式下随机接入过程仿真验证系统级仿真平台有效性。与传统方法相比,该仿真平台可适用于多星、多站、多波束、多链路和多用户自由组网,为卫星移动通信系统协议体制和关键技术的仿真验证提供了一种新的借鉴和参考。     

锁相环行为级建模及在视频行锁相中的应用

锁相环是模拟集成电路的关键技术,首先介绍电荷泵锁相环技术的基本原理、理论推导,然后对两种不同抽象层次的硬件描述语言进行比较.运用Verilog-A语言进行锁相环行为级建模,给出关键模块的代码实现,介绍了在视频信号行锁相中的应用,最后给出了视频信号行锁相仿真结果.该方法大大提升数/模混合仿真速度,解决了视频解码器行锁相问题,并可应用于其他采用模拟镄相环的信号处理系统中.     

博科通信系统宣布收购MCDATA公司

博科通信系统有限公司和McDATA公司宣布达成最终协议，博科将通过股票交易的方式收购McDATA。根据协议，每股McDATAA级普通股和B级普通股兑换0．75股博科普通股。根据2006年8月7日闭市时博科的股价，交易价格相当于每股McDATA股票约4．61美元，或总计约7．13亿美元。交易完成后，McDATA股东将拥有约30％的博科股票。交易预计对McDATA股东免税。     

基于H.264的视频传输系统的设计与实现

针对H.264协议在视频通信中的应用,对基于H.264协议的视频传输系统的结构和功能构成进行了说明,对H.264编解码器的设计实现方法和优化策略进行了阐述,重点说明了该设计实现中H.264编码器的算法级优化和代码级优化的优化策略,以及H.264编解码算法中图像分片的优化控制方法。通过多组标准化测试序列测试结果的比较,分析了优化算法的编码速度和视频压缩质量。     

基于SmartVerif的比特币底层协议算力盗取漏洞发现

比特币引入了一种新的P2P(Peer to Peer)交易方法,并依靠其底层协议实现去中心化交易.然而,由于目前缺乏对比特币各底层协议的细粒度形式化分析和系统建模,比特币安全性并未被保证.本文通过设计多维度的比特币安全模型引理和细粒度的比特币模型规则,系统地抽象了多协议组合运行考虑下的比特币协议实体交互,完成了对比特币的形式化符号建模与自动化安全分析.与以前的工作相比,本文更细粒度地建模了比特币协议实体及其相关操作,并全面设计了满足比特币各实体需求的安全属性.此外,本文利用自动化形式化验证系统SmartVerif实现了无需额外手工推导证明的形式化验证实验,通过将本文所建模的符号模型规则与引理作为SmartVerif的输入,发现了比特币底层协议算力盗取攻击.     

CAN总线通信控制协议的仿真与性能分析

在控制器局域网(CAN)总线通信控制协议的基础上,在MATLAB/Simulink软件Stateflow仿真环境下,利用有限状态机理论对CAN总线通信系统进行了形式化建模。通过此仿真模型,可以分析CAN总线通信系统中负载率的变化对网络吞吐量、平均信息时延、通信冲突率、网络利用率、网络效率以及负载完成率的影响。仿真结果验证了CAN总线通信控制协议的特点,同时也证明了Stateflow对CAN总线协议进行建模仿真的可行性。     

基于Petri网的SET双重签名建模与分析

双重签名是安全电子交易协议的一个重要技术,它将摘要和数字签名结合起来,使得交易中的各方仅得到部分消息即可完成验证从而达成多方协议。论文利用Petri网对双重签名进行建模和形式化描述,并就安全性对此模型进行了分析。     

Ad hoc网络按需路由协议DSR性能研究

该文对无线自组网Ad hoc的基于源驱动的按需路由选择协议DSR进行了系统研究,并利用通信网络仿真建模软件OPNET对全部采用固定节点的Ad hoc网络利用DSR作为其路由协议,分设场景进行仿真,并对DSR协议随着节点数增多所表现出来的性能进行了较为详尽的比较和分析。     

FAST: An RTL Fault Simulation Framework based on RTL-to-TLM Abstraction

Functional verification techniques based on fault injection and simulation at register-transfer level (RTL) have been largely investigated in the past years. Although they have various advantages such as scalability and simplicity, they commonly suffer from the low speed of the cycle-accurate RTL simulation. On the other hand, Transaction-level modeling (TLM) allows a simulation speed sensibly faster than RTL. This article presents FAST, a framework to accelerate RTL fault simulation through automatic RTL-to-TLM abstraction. FAST abstracts RTL models injected with any RTL fault model into equivalent injected TLM models thus allowing a very fast fault simulation at TLM level. The article also presents FAST-DT, a new bit-accurate data type library integrated in the framework that allows a further improvement of the simulation speed-up. Finally, the article shows how the generated TLM test patterns can be automatically synthesized into RTL test patterns by exploiting the structural information of the RTL model extracted during the abstraction process. Experimental results have been performed on several designs of different size and complexity to show the methodology effectiveness.     

A Study of the Simulation Model in WCDMA Systems

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Analytical modeling of bidirectional multi‐channel IEEE 802.11 MAC protocols

This paper presents an analytical approach to model the bi‐directional multi‐channel IEEE 802.11 MAC protocols (Bi‐MCMAC) for ad hoc networks. Extensive simulation work has been done for the performance evaluation of IEEE 802.11 MAC protocols. Since simulation has several limitations, this work is primarily based on the analytical approach. The objective of this paper is to show analytically the performance advantages of Bi‐MCMAC protocol over the classical IEEE 802.11 MAC protocol. The distributed coordination function (DCF) mode of medium access control (MAC) is considered in the modeling. Two different channel scheduling strategies, namely, random channel selection and fastest channel first selection strategy are also presented in the presence of multiple channels with different transmission rates. M/G/1 queue is used to model the protocols, and stochastic reward nets (SRNs) are employed as a modeling technique as it readily captures the synchronization between events in the DCF mode of access. The average system throughput, mean delay, and server utilization of each MAC protocol are evaluated using the SRN formalism. We also validate our analytical model by comparison with simulation results. The results obtained through the analytical modeling approach illustrate the performance advantages of Bi‐MCMAC protocols with the fastest channel first scheduling strategy over the classical IEEE 802.11 protocol for TCP traffic in wireless ad hoc networks. Copyright © 2010 John Wiley & Sons, Ltd.     

Development of electro-hydraulic proportion control system of track-laying machinery for high speed railway construction

This paper mainly deals with the development of electro-hydraulic(EH) proportion control system for travelling and track-laying work in the track-laying machinery (TLM) for high speed railway construction. Different from TLM used to low speed railway construction, TLM for high speed railway construction is a kind of the full-automatic continuous track-laying work machinery, and it is characterized by flowchart process and self-travelling. In order to increase the operation production rate and work quality of the track-laying machinery, a distributed electro-hydraulic proportional control system to be based on controller area network(CAN) bus type of networked control network which can realize the coordinated control among multiple hydraulic implement mechanisms is proposed. In this system, the travelling speed of the TLM is chosen as the primary connected variable of sleeper-working. Using the measured travelling speed of TLM via the triggering-wheel, the developed system can implement the control for the wheel-rail travelling speed and tractive force, the sleeper-laying and sleeper-conveying is constructed. Addressed the coordinated control of the travelling system, a compound cooperated control system is designed for coordinating between the tractive forces and the travelling speeds of the crawler vehicle and the wheel-track work vehicle. For the speeds coordination of multiple-sleeper-conveying-motor, the relative coupling control law is presented based on the threshold type of fuzzy PID. The simulation, the worksite test and the practical application show that the developed control system can meet the requirements of the sleeper-laying operation.     

A performance comparison of the SCM and the Onering channel modeling method for MIMO‐OFDMA systems

This paper compares two types of channel modeling methods, which are the spatial channel modeling (SCM) and the Onering channel modeling method. These two well‐known channel models are proposed for 4G wideband mobile communication networks. To compare the performance of these channel modeling methods, we analyze the properties of the spatial, temporal, frequency correlation functions simulated by using these methods. The correlation functions of the two channel models are compared in the same conditions of antenna arrangements. The simulation and calculation results show that the correlation functions of Onering and SCM channel models are very close to each other if the BS and the MS antenna arrays are parallel and perpendicular to the broadside of MS‐BS. In other cases, the correlation functions of the two models are slightly different; however, their shapes are similar. These differences can be explained that the Onering model hardly fully describes all the characteristics of 4G channels as the performance SCM model does. The performance of these channel modeling methods is compared in system simulation level—MIMO‐OFDMA systems. The combination SFBC‐MMSE is used for spatial channel coding and the signal detection. The simulation results show that the system performance obtained by using these two channel models are comparable, given that the both modeled channels have same parameters and antenna directions. Copyright © 2016 John Wiley & Sons, Ltd.     

基于阵列单通道的机动目标DOA跟踪方法

针对现有利用阵列单通道系统对机动目标跟踪精度不高,实时性差等不足,提出了一种新的基于改进粒子滤波算法的阵列单通道机动目标波达方向(direction of arrival, DOA)跟踪方法。该方法首先在利用接收机轮流采样建立数学模型的基础上,建立跟踪模型。然后,利用粒子群优化算法对马尔科夫链蒙特卡罗(Markov Chain Monte Carlo, MCMC)粒子滤波算法的重采样环节进行优化处理,给出了一种交互MCMC粒子滤波算法,该算法克服了传统粒子滤波算法粒子退化及样本贫化的固有缺陷。最后利用该算法求解跟踪方程,实现了实时DOA估计。理论分析与仿真结果表明,本文方法可实现基于阵列单通道的DOA跟踪与波束形成一体化,且能够处理相干信号,与标准粒子滤波和子空间类算法相比,收敛速度快,跟踪精度高。      

Exploiting UML based validation for compliance checking of TLM 2 based models

SoC system designers commonly employ SystemC based Transaction level modeling (TLM) for its early software development usage and its analysis capabilities. TLM helps in realizing a SoC using virtual prototyping by integration of SoC components at different abstraction levels. The TLM 2 standard introduces interoperability rules for the models that may have been developed independently. However, neither SystemC compiler nor TLM library supports checking of such rules and manually debugging interoperability errors in such models could be a major problem. This provides motivation for developing automatic compliance checking techniques which can detect and report such errors. As the models are refined to incorporate detailed intercommunication protocols among the system components, the need for compliance checking extends to these protocols as well. In this paper, we present an efficient UML based compliance checking technique for TLM 2 models which supports static, dynamic and protocol-specific rule checking.     

Saturation throughput analysis of a carrier sensing based MU-MIMO MAC protocol in a WLAN under fading and shadowing

In wireless local area networks (WLANs), the traditional carrier sense multiple access with collision avoidance (CSMA/CA) medium access control (MAC) protocol cannot use the full benefits from multiuser multiple-input multiple-output (MU-MIMO) technique due to random medium access of the users. In this paper, we propose a carrier sensing based MAC protocol for a MU-MIMO based WLAN with full utilization of MU-MIMO technique. By modeling the WLAN system under the proposed MAC protocol as a discrete time Markov chain, we develop an analytical model for computing the saturation throughput in presence of path loss, Rayleigh fading and log-normal shadowing. The analytical model is then validated via simulation. By means of numerical and simulation results, we demonstrate that the proposed MAC protocol significantly improves throughput performance than the traditional CSMA/CA MAC protocol. Further, we compare the performance of the proposed MAC protocol with a MU-MIMO MAC protocol called Uni-MUMAC protocol and find that the proposed MAC protocol performs better than the Uni-MUMAC protocol. We also explore the effect of some of the network and wireless channel parameters on the performance of the proposed MAC protocol.