纯ATM实时多媒体通信系统设计方案

探讨了异构计算环境下的实时多媒体通信以及ATM（异步传输模式）网络上能提供服务保证的高性能宽带多媒体应用，设计了异构环境下基于Native-ATM(纯ATM）方式的实时多媒体通信系统，该系统在两不同的计算机系统之间实现了基于ATM AAL5协议的实时多媒体通信数据流的互通，为异构环境下宽带分布多媒体应用的研究创造了良好的基础。     

Target software generation: an approach for automatic mapping of SystemC specifications onto real-time operating systems

In this paper we present a new approach for automated target code generation for given real-time operating systems out of SystemC to support platform independent software development. Since SystemC becomes the most important language in electronic system level design, the support of a seamless design flow becomes an important task. During the system design process, SystemC is used to develop a “Golden Reference Model” that provides a well-suited platform for specification, simulation, and verification of embedded systems. Based on the “Golden Reference Model,” an important task of the design process is to map applications, that have been described either in C++ or directly in SystemC, to the specific real-time operating system which is running at the target processor. Since a manual mapping approach is time-consuming and error-prone, the mapping process should be performed automatically. This paper presents a new method for automated generation of code for a specified operating system just by using an abstract XML representation of the RTOS API.     

A survey on estimating the timing constraints of hard real-time systems

A real-time computer system must interact with its environment in terms that are dictated by the occurrence of a significant event or simply by the passage of time. The computational activities triggered by these stimuli are expected to provide the correct results at the right time, since a real-time controller must meet the timing constraints that are dictated by its particular environment. If a computer controller fails to meet these time constraints, the controlled system may suffer a behavioural degradation from where, in some cases, a catastrophe can emerge. Thus, the correct estimation and handling of the timing constraints of a controlled system are central issues for the specification, development and test of a real-time computer controller, in a job that requires the scientific contribution of system engineers and real-time computer designers.In this paper we survey proposed solutions and concepts for estimating the timing constraints and the behavioural degradation of a controlled system when it suffers the impact of a timing failure. Although it is universally agreed that these are central issues for the development of predictable real-time controllers, this study shows that, except for a few cases, current literature does not place on them as much emphasis as one could expect. Moreover, a systematic method for evaluating the timing constraints of a controlled system does not seem to actually exist.     

光通信系统中前向纠错码的一种改进方案

对现有的前向纠错(FEC)编码技术提议了一种基于交织连续型级联码的改进方案.仿真结果分析表明:具有交织的连续型级联码RS(255,239) RS(255,239)和RS(255,239) RS(255,223)是两种纠错性能优良、冗余度适中、易于实现的码型,在误码率为10-12时,它们的净编码增益(NCG)比RS(255,239)码分别大2dB～3dB,因而它们更适用于高速长距离光通信系统.最后,探讨了该新型级联码的帧结构安排,为其硬件的设计打下了一个坚实的基础.     

Handover mechanism and speed considerations in personal communication systems

In this paper, we discuss views concerning different approaches to the analysis of personal communication systems (PCSs): an outside observer's point of view, a user's point of view, and a base station's point of view. In these three approaches the paper focuses on the handover mechanism rather than on the data traffic modeling. In particular, we reexamine these different methods of analysis, combine these views with our approach, and propose a new queueing model. We take into account the speed factor and show that the ordinary measurements that are based on the state probabilities are not appropriate. In addition, we propose a layered queueing model in which low-speed and high-speed users are treated differently.     

A general time model for the specification and design of embedded real-time systems

Design of complex embedded systems feasible with current and upcoming semiconductor technologies necessitates consideration of real-time from the beginning. However, the commonly used specification techniques do not consider temporal aspects in general like fulfillment of high level timing requirements or dynamic reactions on timing violations. In this paper, we discuss the restrictions of current specification techniques for embedded real-time systems and present a general time model that solves this issue. The time model contains the progress of time, the measurement of time and the specification of timing requirements based on event traces. In contrast to earlier techniques, preconditions determine the actual relevance of a specific timing bound. Exemplified for SDL, a solution for the specification of temporal aspects is shown. The advantages of this solution are discussed in a hardware/software co-design case study from the mobile communication area.     

基于FEC的LDPC编码在远距离光通信系统中的研究

在研究超强FEC的LDPC编码在光通信中的应用性能分析的基础上,设计了采用超强FEC技术的OTU,给出了LDPC编码器与译码器具体设计,最后进行了实验方案分析和LDPC码型在远距离光通信系统中的仿真.     

智能反射表面辅助的无线通信系统的物理层安全综述

为了满足未来无线通信系统高谱效、高能效的要求,智能反射表面(IRS)技术得到了广泛的关注与研究。通过对IRS进行设计优化,能够从不同的角度增强无线通信系统的物理层安全(PLS)。基于此,对现有的IRS增强物理层安全的研究进行整理,从信息理论安全、隐蔽通信、密钥生成等主要方向对现有研究进行了归纳总结,阐述了各研究热点的模型特点和关键方法。最后,对IRS增强的物理层安全进行了总结梳理,并探讨了未来的研究热点方向。     

Energy minimization by exploiting data redundancy in real-time wireless sensor networks

In this paper, we devise scheduling algorithms to minimize energy consumption in Real-time Wireless Sensor Networks (WSNs) by leveraging the energy-delay tradeoff. Spatial and temporal correlation exhibited by WSNs can be exploited to reduce energy consumption. Previous research works attempt to exploit this correlation by way of aggregation or adaptive sampling. We propose determination of the data correlation at each node by way of local computation and propose avoiding transmission of significantly similar data. This can lead to unused time slots at runtime (dynamic slack) which can be traded off for energy savings. Our approach uses techniques namely Dynamic Voltage Scaling (DVS) and Dynamic Modulation Scaling (DMS), which utilize the slack generated dynamically to reduce energy consumption in a real-time environment. We propose heuristics with varying complexities for efficient slack management. We evaluate the performance of these heuristics by simulating diverse network conditions while incorporating different overheads. Our results show that the proposed heuristics can achieve energy savings up to 40% more than the baseline algorithms employing DVS and DMS, and, can achieve performance competitive with a Clairvoyant algorithm under network scenarios with high volume of redundant messages.     

智能反射表面辅助的无线通信系统的物理层安全综述

为了满足未来无线通信系统高谱效、高能效的要求,智能反射表面(IRS)技术得到了广泛的关注与研究。通过对IRS进行设计优化,能够从不同的角度增强无线通信系统的物理层安全(PLS)。基于此,对现有的IRS增强物理层安全的研究进行整理,从信息理论安全、隐蔽通信、密钥生成等主要方向对现有研究进行了归纳总结,阐述了各研究热点的模型特点和关键方法。最后,对IRS增强的物理层安全进行了总结梳理,并探讨了未来的研究热点方向。     

短波通信中分布式干扰的效能分析

在短波通信中,分析分布式干扰应用,深入分析分布式干扰设备组成、关键技术,随机二维码调制信号.应用Matlab软件模块,对分布式干扰系统进行分析,采用随机二元码,调制信号对短波通信系统的干扰影响.通过仿真结果可知,分布式干扰能够获取显著干扰效果.在本文研究中,围绕短波通信展开讨论,重点分析分布式干扰的效能问题,仅供参考.     

双向实时通信冲突解决方案研究

在工业生产中,产品了获得工业设备信息,需要实时与计算机进行通信。工业设备获取传感器的信息,需要RS 485,SPI,CAN等接口实时与传感器设备通信。当二者同时时,微控制器产生中断冲突,造成设备数据丢失或控制计算机的通信死机。为了保证产品的稳定性,提出了一种基于双微控制器,并同时利用异步FIFO实现双向通信的速度匹配和数据交换。实验证明该方法有效地解决双向实时通信产生的通信的中断冲突,保证工业设备的稳定性和数据通信的准确。     

Energy efficiency of massive MIMO wireless communication systems with antenna selection

Massive multiple-input multiple-output (MIMO) requires a large number (tens or hundreds) of base station antennas serving for much smaller number of terminals, with large gains in energy efficiency and spectral efficiency compared with traditional MIMO technology. Large scale antennas mean large scale radio frequency (RF) chains. Considering the plenty of power consumption and high cost of RF chains, antenna selection is necessary for Massive MIMO wireless communication systems in both transmitting end and receiving end. An energy efficient antenna selection algorithm based on convex optimization was proposed for Massive MIMO wireless communication systems. On the condition that the channel capacity of the cell is larger than a certain threshold, the number of transmit antenna, the subset of transmit antenna and servable mobile terminals (MTs) were jointly optimized to maximize energy efficiency. The joint optimization problem was proved in detail. The proposed algorithm is verified by analysis and numerical simulations. Good performance gain of energy efficiency is obtained comparing with no antenna selection.     

基于国产SoPC平台的外部总线的设计与实现

可重构的SoC(system-on-a-chip)是嵌入式系统发展的一个重要方向,它不仅可以达到较高的性能而且更加的灵活.介绍了一种国产的SoPC(System on a Programmable Chip)平台,并基于此平台提出了一种用于重构计算的外部总线结构.通过该总线,可以通过改变不同的IP(intellectual property)核来组成新的系统.同时回顾总结了部分动态可重构的步骤并完成了一个完整的系统,最后给出了可重构系统的测试结果.     

基于双消息队列机制的医疗协同实时通讯

目的：开发一个实时通讯系统,达到各个应用系统融合的目的,增强医院各个科室之间工作协同性,增强信息传递可靠性,保密性,提高反应能力。方法：系统通过采用双消息队列机制来处理全院的SOCKET消息,一个队列负责接收消息,一个队列负责转发消息的方法。系统预置消息协议实现在医院网络中可靠高效的传输,可定义不同的消息号区分消息类别,对发送消息进行加密处理。系统还根据紧急程度,给消息划分了优先级。结论：在医护通讯,院内OA,排队叫号,患者危急值处理,院内报警,患者入院协同,手术协同管理等系统中都可广泛应用,提高了反应能力,减少了患者等待时间,提高了部门之间协同性,取得了很好的应用效果。     

智能交通系统蓝牙车载电话的嵌入式实现

完善的智能交通系统应具备与公交车无线通信的能力，以灵活掌握公交车的运营情况，进行合理的调度。给出智能交通系统蓝牙车载电话(Hands Free Set)在嵌入式系统下的解决方案，包括HFP／PAP的工作原理、工作流程，软件结构，硬件设计与设计实例。     

Protocol Buffers在即时通讯系统中的应用研究

即时通讯系统已经广泛应用在人们的生活中,随着用户数量的增长,计算机设备在网络中传输的数据量越来越大。由于网络中的数据传输是非结构化的,因此需要数据的序列化与逆序列化方法来实现网络数据到可读数据的转换。基于即时通讯系统对于数据的实时性需求,提出了使用Protocol Buffers作为系统的序列化与逆序列化的手段,并且将Protocol Buffers与目前几种比较主流的数据序列化方法进行了对比。     

无线通信系统中的MEMS天线

本文分析了常见的MEMS天线及其应用,包括多对称锥形弯曲缝隙微带天线、用于WLAN中的微尺度宽频天线、开关式微机械毫米波天线、微机械自适应贴片天线等,对这些天线的结构原理、制造方法及其性能做了分析。这些天线设计简单、可用CMOS工艺制造、利于集成,兼有宽频、高辐射效率、小尺度等优点。但相对普通天线而言,这些制造工艺明显复杂、尺度更微小,增加了实现难度,要实现MEMS天线批量应用,还需要在基础理论及其微细工艺进行研究。最后,对MEMS天线在无线通信系统中的应用作出展望。