A communication server for telemedicine applications

Telemedicine applications, in some cases, need multipoint-to-multipoint communication. To meet the requirement of telemedicine communication, the development of a medical communication server is proposed in this paper. To make a working, as well as cost-effective, communication platform for the telemedicine applications, a specially designed communication server model is proposed in this work. This server is able to provide an effective multipoint-to-multipoint communication service for any level applications in telemedicine. The implementation program of this server is developed in a Windows '95 environment by using a winsocket. The trial application testing in a telemonitoring system is also presented to demonstrate the feasibility of taking such a structure with the server. By using the architecture of such a communication server in telemedicine applications, the multipoint-to-multipoint communication is easily managed and the communication processes are simplified and well controlled by the server     

终端直通技术中通信系统模式的研究

随着移动通信的不断发展,5 GHz以下带宽分配已经十分拥挤,由于可用于移动通信的频谱资源有限,为满足无线通信发展的需要,可以用终端直通技术(D2D,Device-to-Device)来提高频谱利用率,并可以减少和基站通信的负担,这是新一代无线通信发展的趋势。但是在D2D通信系统中所选择的模式是十分关键的问题。这里给出了蜂窝模式和直通模式这2种通信模式,为了能更好地选择D2D的工作模式,通过仿真比较了这2种模式性能的优劣。     

无线通信电台的通信协议研究

通信协议是通信系统在通信链路上实现复杂任务的软件构架及程序编写规则,任何通信系统之所以能正常工作离不开通信协议的支持。本文以研制一种通信电台为例,提出了一种适合无线通信电台的通信协议,实验结果证明此协议具有很好的性能。     

Fuzzy Reasoning for Wireless Awareness

In hybrid communication environments where both wired and wireless links exist, performance of the quality-of-service (QoS) provision can be enhanced if an application knows whether there exist wireless links in the communication channel and adapts its behavior accordingly. This paper presents a scheme using fuzzy reasoning to make applications wireless-aware. Based on the studies of statistical patterns of round-trip time (RTT) in communication sessions via wired and wireless links, the mean value and variance of RTTs are used as fuzzy inputs, and the confidence of existence of wireless links in the communication channel as the fuzzy output. Simulations and experiments show that fuzzy reasoning for wireless awareness (FuRWA) is a feasible way to enhance QoS in hybrid communication environments at the application layer. FuRWA adds intelligence into endpoints without modifying protocol stacks, and can handle scenarios where a wireless link is an intermediate component of a communication path.     

Network architecture and communication modules for guaranteeing acceptable control and communication performance for networked multi-agent systems

When sensory and actuation devices in a control system are exchanging data through one common communication medium, the sharing of communication bandwidth will induce unavoidable data latency and might degrade the control performance. Hence, the utilization of communication resource and the requirement of control specification should be analyzed and properly designed when implementing a control system over a network architecture. In this paper, we analyze the performance of information sharing of multiple cooperative agents over one communication network, and propose design methodologies of guaranteeing acceptable control and communication performance in a networked control system. In particular, we study the relationship between the sampling rates of a control system,and the transmission rates of a communication network, and then utilize an integrated networked control design chart to help select design parameters and visualize overall system performance at different sampling and transmission rates. Based on the design parameters selected, the communication modules by utilizing deadband control and state estimation are presented for guaranteeing both control and communication performance. Simulation studies are conducted in a network-and-control simulation tool that is developed on the Matlab/Simulink platform and is used to demonstrate the proposed design methodologies. Both the analysis and simulation results illustrate the characteristics of designing mechanisms between control and communication performance and show the improvement of implementing the proposed communication modules.     

码分多址通信的计算机仿真

随着通信技术的发展，通信系统的研究成为一项越来越复杂的工程，所以，对通信系统的仿真就日益成为一种重要的研究手段。本文介绍一种对CDMA码分多址通信系统进行计算机仿真的方法。该方法基于通信过程的基本特征，充分利用软件系统的技术特点，具有非常好的可扩展性和执行速度。通过把仿真结果同理论结论进行对比，证明该仿真方法非常有效。     

Web聚合应用的安全跨域通信机制

针对聚合应用现有的多种跨域通信方案难以同时兼顾安全性和高效性,提出适合聚合应用的安全跨域通信(SCDC,secure cross-domain communication)系统,将不同信任域内容封装成安全组件,借助于分层通信栈实现域间通信,并通过封装对象实现细粒度对象共享。保障了聚合应用与组件间的安全跨域通信与对象共享,且不需要浏览器做任何修改。实验表明,系统引入了有限的开销,而通信效率提高了5倍以上。     

通信传输网络发展规划新思路探索

通信传输网络是21世纪人们沟通的桥梁。随着通信传输网络的发展,人们的信息传输进入了方便、快捷、高效时代,通过这些通信传输网络,人们的通信方式演化为网络通信,纸质通信成为辅助渠道。文章介绍了通信传输网络的发展现状,分析了通信传输网络发展规划,并对通信传输网络发展的思路进行探索。     

面向光纤通信的大气激光应急通信系统设计

应急通信是指在突发事故造成通信中断或通信阻塞情况下的临时通信。结合应急通信的特点,给出一个面向光纤的大气激光应急通信系统,较为详细地说明了该系统中应急数字光端机的各模块功能,分析了PPM调制和锁相环原理和作用,最后指出了应急通信系统的应用前景。     

短波天波通信链路计算模型研究

为建立远程舰艇短波通信可靠通信链路,简化短波通信工程中天线和通信台站设计过程,研究设计了一个完整的短波通信链路计算模型。该模型包含天线辐射特性计算模型、短波通信电路计算模型、短波天线数据库和通信链路地理参数数据库四大部分。在此基础上,使用该模型进行了实例分析,确定了在一定条件下的工作频率、反射模式,预估场强强度,为短波天波通信工程设计提供依据。     

Broadcast communication operations for hyper hexa-cell interconnection network

The hyper hexa-cell (HHC) interconnection network is relatively a new interconnection network, which is constructed from hexa-cell and hypercube topologies. HHC is developed to support parallel algorithms for solving computation and communication intensive problems. Thus, in order to support solving these problems efficiently, this paper presents two broadcast communication operations for HHC using store-and-forward technique; namely, one-to-all and all-to-all broadcast operations; which allow a message to be transmitted through the shortest path from the source node to all other nodes. The broadcast communication operations are evaluated analytically in terms of communication steps, communication latency, communication cost, and speed over HHC and wraparound square mesh interconnection networks. The analytical results over HHC show that in both one-to-all and all-to-all broadcast operations, the maximum communication steps are \( d + 2\), where d is the dimension of HHC, which is a small integer number. Also, the communication latency increases linearly when the network size increases, and the communication cost for the broadcast operations is equal to O(\(2^{d-1})\). Moreover, the speed of both broadcast operations on d-dimensional HHC is \(d+2\times \) speed of electronic links. In comparison between HHC and wraparound square mesh, one-to-all and all-to-all broadcast communication operations over HHC perform much better than mesh in terms of maximum communication steps, communication latency, and speed.     

面向未来无线通信系统的小蜂窝网络综述

为了满足人们日益增长的数据流量需求,未来无线通信系统将向更小的小区部署迁移.小蜂窝网络是下一代无线通信系统的关键技术,也是适应未来更加复杂通信环境的有效途径.首先介绍了小蜂窝网络的基本概念,论述了其主要的技术特点和独特的应用优势,分析了其在未来无线通信系统中与其他各种技术可能的融合场景并讨论了对应的特点和存在的难题;然...     

Synchronization techniques for underwater acoustic communications

Underwater acoustic channel is a challenging medium for communication due to the presence of significant multipath, high noise, frequency-dependent propagation loss, and high and non-uniform Doppler spread. Doppler shift is non-negligible in underwater communication due to the low velocity of underwater signals. Synchronization and Doppler estimation are important requirements for achieving good performance in this channel. Synchronization algorithms that give good performance in radio communication do not work well in underwater communication. Hence, this area has received a lot of attention from researchers. This paper surveys important works in the area. The techniques proposed in the literature for frame synchronization, frequency and phase synchronization, and timing synchronization in single carrier communications are reviewed here. The synchronization techniques proposed for OFDM, MIMO OFDM, and spread spectrum communication are also surveyed. Doppler estimation methods proposed in the literature are also reviewed. It is found that most of the recent works in underwater acoustic communication focus on OFDM synchronization. Deep learning-based methods proposed in the literature are also reviewed. Key open problems and areas that require future research attention in the field of synchronization and Doppler estimation in underwater communications are highlighted in this paper. The area needing most attention of underwater communication researchers was found to be MIMO OFDM due to the difficulty in synchronization in such systems while used in underwater communication. Reducing the computational complexity of the algorithms used is also important for future work. Schemes that work with Doppler due to relative velocity over 10 m/s also need to be developed.     

一种大规模分布式计算负载均衡策略

 大规模和超大规模计算系统中的通讯延迟成为影响负载均衡性能的一个重要因素,且延迟具有时变性,而传统的负载均衡策略通常假设通讯固定不变或不考虑通讯延迟开销.本文考虑了系统的通讯延迟开销和延迟时变性特征,给出一种基于广义神经网络(GNN)的层次结构负载均衡策略.该策略具有三个特点:(1)通讯优化的层次结构能够降低大规模计算系统的负载均衡开销;(2)考虑了节点计算速率及通讯延迟时变特性;(3)通过延迟预测可优化任务的通讯延迟和迁移延迟开销.仿真实验验证了该策略在通讯和负载均衡开销方面的性能.     

A multipoint communication service for interactive applications

The multipoint communication layer (MCL) is a generic multipoint communication service designed to support highly interactive multimedia conferencing applications. It supports full-duplex multipoint communication between an arbitrary number of connected locations over a variety of networks. MCL design was driven by the demanding real-time multipoint communication requirements of MICA (multimedia interactive conferencing application). The authors establish the context for MCL by considering MICA's communication requirements and reviewing related work in the area of multipoint communication. They present the overall design of the MCL service and describe its communication primitives, protocol message structures, and implementation. Comparison is made with alternative strategies and the use of MCL services for other applications is examined     

基于多频带陷波的雷达嵌入式通信波形设计

雷达嵌入式通信（radar-embedded communication,REC）系统是一种在雷达回波信号中隐藏通信信息的隐蔽通信方法。但是由于雷达系统所处的电磁波环境极为复杂,以致雷达嵌入式通信系统会受其他通信系统的同频干扰,最终导致接收机无法准确识别回波信号。为了使得雷达系统避免复杂环境的干扰且能保持良好的隐蔽通信性能,本文提出了一种基于多频带陷波的雷达嵌入式通信波形设计。本文首先根据随机雷达波形和理想功率谱密度,并采用功率谱匹配的方法建立目标函数,然后利用拟牛顿优化算法对目标函数进行求解得到多频带陷波,以此来避免其他通信系统带来的同频干扰问题,最后基于多频带陷波,采用一种改进的加权组合方法（improved weighted-combining,IWC）设计通信波形。仿真结果表明,本文所提方法可以保证雷达通信的低误码率（signal error rate,SER）和低拦截率（low probability of intercept,LPI）。      

未来移动通信系统中的无线资源管理

文章结合当前正在研究的后3代(B3G)、第4代(4G)移动通信系统的发展和处于运营及推广阶段的第3代移动通信系统,分析了未来移动通信系统中无线资源管理系统的关键技术,探讨了多体制标准下的无线通信网络和多种业务情况下的无线资源管理的研究方向。     

Power-One通信电源监控系统通信协议破解

根据数据链路层通信协议的一般格式,对串口监听工具截取的Power-One通信电源监控系统中的通信信息进行了逻辑推理和分析,破解了其通信协议的格式和各种通信命令。实验表明,破解结果正确无误。对于通信电源分布式监控系统通信协议的设计和实现,具有一定的借鉴意义。     

基于作战机群的临近空间通信网体系结构设计

在未来空战中,为实现作战机群之间的超视距通信,提出将临近空间通信平台引入战场。首先结合作战机群战场通信的实际情况,设计了临近空间通信网的网络结构;在此基础上,参考开放系统互连体系(OSI)协议模型和数据链的通信协议模型,设计了临近空间通信网的协议结构;最后对影响临近空间通信网络作战性能的指标进行了评估,结果表明临近空间通信网体系结构的设计具有工程上的可行性。