Faster Deterministic Communication in Radio Networks

We study the communication primitives of broadcasting (one-to-all communication) and gossiping (all-to-all communication) in known topology radio networks, i.e., where for each primitive the schedule of transmissions is precomputed based on full knowledge about the size and the topology of the network. We show that gossiping can be completed in time units in any radio network of size n, diameter D, and maximum degree Δ=Ω(log n). This is an almost optimal schedule in the sense that there exists a radio network topology, specifically a Δ-regular tree, in which the radio gossiping cannot be completed in less than units of time. Moreover, we show a schedule for the broadcast task. Both our transmission schemes significantly improve upon the currently best known schedules by Gąsieniec, Peleg, and Xin (Proceedings of the 24th Annual ACM SIGACT-SIGOPS PODC, pp. 129–137, 2005), i.e., a O(D+Δlog n) time schedule for gossiping and a D+O(log ³ n) time schedule for broadcast. Our broadcasting schedule also improves, for large D, a very recent O(D+log ² n) time broadcasting schedule by Kowalski and Pelc. A preliminary version of this paper appeared in the proceedings of ISAAC’06. F. Cicalese supported by the Sofja Kovalevskaja Award 2004 of the Alexander von Humboldt Stiftung. F. Manne and Q. Xin supported by the Research Council of Norway through the SPECTRUM project.     

An O ( n 1.5 ) Deterministic Gossiping Algorithm for Radio Networks

   Abstract. We consider the problem of distributed gossiping in radio networks of unknown topology. For radio networks of size n and diameter D , we present an adaptive deterministic gossiping algorithm of time O (

集散控制系统的通讯网络

集散控制系统的关键问题是通讯,作为其“神经网络”的通讯网络,是其重要支柱。与集散控制系统的三级结构相适应,通讯网络也具有多级结构,这就决定了它的复杂性。因此必须分清网络拓扑与网络通讯协议的种类与适用范围,慎重选择。详细分析了网络堵塞与死机现象的原因,采用了逆向工作站、加大例外报告区域以及选用匹配的操作站与监控软件等解决方案,经实际应用,网络堵塞与死机已基本得到控制。     

Centralized asynchronous broadcast in radio networks

We study asynchronous broadcasting in packet radio networks. A radio network is represented by a directed graph, in which one distinguished source node stores a message that needs to be disseminated among all the remaining nodes. An asynchronous execution of a protocol is a sequence of events, each consisting of simultaneous deliveries of messages. The correctness of protocols is considered for specific adversarial models defined by restrictions on events the adversary may schedule. A protocol specifies how many times the source message is to be retransmitted by each node. The total number of transmissions over all the nodes is called the work of the broadcast protocol; it is used as complexity measure. We study computational problems, to be solved by deterministic centralized algorithms, either to find a broadcast protocol or to verify the correctness of a protocol, for a given network. The amount of work necessary to make a protocol correct may have to be exponential in the size of network. There is a polynomial-time algorithm to find a broadcast protocol for a given network. We show that certain problems about broadcasting protocols for given networks are complete in NP and co-NP complexity classes.     

PC机与单片机系统无线通信及其实现

介绍了一种通过数传电台实现PC机与单片机系统间主从式无线组网方法。并根据通信的需要制定了系统的通信协议,实现主从地址的识别以及误码的判断。此外采用单字节多次收发的方法,实现下位单片机与上位PC机系统的通信。大量实验证明,所制定的通信协议可以很好地实现无线数传电台间多址通信中数据的可靠接收和发送。     

Faster communication in known topology radio networks

This paper concerns the communication primitives of broadcasting (one-to-all communication) and gossiping (all-to-all communication) in known topology radio networks, i.e., where for each primitive the schedule of transmissions is precomputed in advance based on full knowledge about the size and the topology of the network. The first part of the paper examines the two communication primitives in arbitrary graphs. In particular, for the broadcast task we deliver two new results: a deterministic efficient algorithm for computing a radio schedule of length D + O(log³ n), and a randomized algorithm for computing a radio schedule of length D + O(log² n). These results improve on the best currently known D + O(log⁴ n) time schedule due to Elkin and Kortsarz (Proceedings of the 16th ACM-SIAM Symposium on Discrete Algorithms, pp. 222–231, 2005). Later we propose a new (efficiently computable) deterministic schedule that uses 2D + Δlog n + O(log³ n) time units to complete the gossiping task in any radio network with size n, diameter D and max-degree Δ. Our new schedule improves and simplifies the currently best known gossiping schedule, requiring time , for any network with the diameter D = Ω(log ⁱ⁺⁴ n), where i is an arbitrary integer constant i ≥ 0, see Gąsieniec et al. (Proceedings of the 11th International Colloquium on Structural Information and Communication Complexity, vol. 3104, pp. 173–184, 2004). The second part of the paper focuses on radio communication in planar graphs, devising a new broadcasting schedule using fewer than 3D time slots. This result improves, for small values of D, on the currently best known D + O(log³ n) time schedule proposed by Elkin and Kortsarz (Proceedings of the 16th ACM-SIAM Symposium on Discrete Algorithms, pp. 222–231, 2005). Our new algorithm should be also seen as a separation result between planar and general graphs with small diameter due to the polylogarithmic inapproximability result for general graphs by Elkin and Kortsarz (Proceedings of the 7th International Workshop on Approximation Algorithms for Combinatorial Optimization Problems, vol. 3122, pp. 105–116, 2004; J. Algorithms 52(1), 8–25, 2004). The second author is supported in part by a grant from the Israel Science Foundation and by the Royal Academy of Engineering. Part of this research was performed while this author (Q. Xin) was a PhD student at The University of Liverpool.     

无线通讯网络可靠度的计算

文章提出了几个保持可靠度不变的将边可靠、结点不可靠的无向网络化简以及转化成有向网络的原则,并将这些原则与已有的不交和或容斥原理方法相结合给出了一个新的计算无线通讯网络（Radio Communication Network,简称RCN）两终端可靠度的有效算法。由于文章所给的化简与转化使RCN中指定两结点之间的路径数大大减少,因此该文算法使其可靠度的计算得到很大简化。     

分布式多媒体系统中的通信机制

随着信息高速公路的兴起，分布式多媒体系统越来越受到人们的重视，同时也向网络通信机械提出了新的挑战，该文首先介绍分布式多媒体系统中通信机制所涉及的一些重要的基本概念及其基本特点，然后从服务网络，网络服务和通信协议３个方面介绍网络通信机制对分布式多媒体系统的支持，最后得出结论。     

分组无线网缠绕多路径数据路由协议仿真

在分组无线网的路由协议中,传统路由协议在恶意节点数目较多时网络吞吐量较低,因此提出一种分组无线网缠绕多路径数据路由协议,利用获取的源节点数量信息与位置信息进行路由发现;根据路由发现结果建立从汇聚节点至源节点之间的路径,从而建立缠绕多径路由;对缠绕多径路由进行建簇与重构;进行支路径数优化,从而实现分组无线网缠绕多路径数据路由协议的构建。为了验证上述路由协议的网络吞吐量,将路由协议与基于链路状态的主动式多路径路由协议、基于动态源的按需式多路径路由协议、基于距离矢量的混合式多路径路由协议进行对比,上述四种路由协议在恶意节点数目为30时的网络吞吐量分别为69.5%、33.5%、23.6%、4.2%,通过比较可知,新提出的路由协议的网络吞吐量最高,证明了新路由协议的性能。     

浅析广电网络中的光纤通信技术及应用比较

光纤通信技术无论是在广播电视网络已有的HFC架构下,还是在广电网的双向改造方式中,都是必不可少的。本文浅要介绍了光纤通信系统的组成、功能以及在广电网络中的应用比较。     

A Routing Protocol for Enhanced Efficiency in Cognitive Radio Networks

This paper proposes a novel routing protocol enriched with an assigning mechanism that enables for efficient data flow coordination, among communication nodes with heterogeneous spectrum availability in distributed cognitive radio networks. Efficient routing protocol operation, as a matter of maximum-possible routing paths establishments and minimum delays is obtained, by utilizing a signaling mechanism that was developed based on a simulation scenario. This simulation scenario includes a number of secondary communication nodes, operating over TVWS （television white spaces） under the ＂spectrum of commons＂ regulation regime. The validity of the proposed routing protocol for enhanced efficiency in cognitive radio networks is validated, by conducting experimental simulations and obtaining performance evaluation results. Simulation results verified the efficiency of the proposed routing protocol for minimizing routing delays among secondary communication nodes and indentified fields for further research.     

局域网通信协议的作用及配置

通信协议是网络设备用来通信的一套规则，局域网中常使用3种通信协议即：NetBEUI协议，IPX／SPX及其兼容协议和TCP／IP协议，通过对3种通信协议的比较，给出它们的工作原理及分别使用的网络环境，对于TCP／IP协议的IP地址的使用，子网的划分及网络连通性测试进行了深入的探讨，并且给出了具体的配置测试实例及解决问题的方法，在实际使用中，只有根据网络自身特点选用合适的网络协议，并且进行必要的配置及测试，才能提高网络的通信速度，增强网络的安全和稳定运行。     

一种350MHz警用集群系统无线信道控制板的设计与实现

文章介绍了已研制成功的一种用于350MHz警用集群系统的无线信道控制板,对其硬件结构、设计过程、控制算法和信令纠错及软件编制作了描述。     

有关计算机网络对等安全通信技术的研究

在计算机网络通信过程中,以服务器作为重要载体,实现了信息的中转通信作用。随着信息内容的大幅度增加,为了缓解服务器压力、保障数据通信效率,必须通过网络协议实现编程接口功能,支持网络节点之间实现同步传送,而对等安全通信则是这一过程的重要保障,可有效提高网络环境中的安全性。本文结合当前对等安全通信技术的几种常见形式,对相关技术内容进行分析与探讨。     

热连轧仿真系统中网络通信过程的设计与实现

热连轧计算机仿真系统中的客户机与服务器之间采用TCP协议进行通信.分析了服务器端事件、客户端事件与基于TCP协议的网络通信过程的对应关系,并在此基础上,给出了Winsock在热连轧仿真系统中的应用实例,并详细介绍了整个网络通信过程的设计与实现.     

集群局域网内高性能通信协议的研究

集群已经成为了主流的并行计算平台,但集群计算系统的性能受限于互连通信的开销、延时和带宽。随着技术的不断改进,通信瓶颈从原来通信路径上的带宽转移到通信处理的软件开销。为了充分发挥硬件通信性能,作者提出、研究、设计和实现了局域网内高性能通信协议。该协议的突出特点是充分利用了集群局域网的高速高可靠特点,简化协议处理开销,达到通信的高效性;提出了数据合并的思想,能将大量的小消息合并成大消息传输,能充分提高传输性能。经测试,该协议的性能比传统TCP/IP协议有较大改进。     

煤矿井下无线传感网络通信关键技术的研究

煤矿井下环境监测是无线传感网络的应用之一,要求监测数据必须通过土壤、煤岩传输,这给无线通信技术提出了新的挑战。文章分析了煤矿井下无线传感网络通信技术面临的问题,证明了井下信道特性与土壤、煤岩特性,特别是与湿度相关。为降低能耗、克服高损耗,文章在分析了陆地无线传感网络的通信协议的基础上,对无线传感网络的通信协议提出了修改建议。此外,为提高网络效率和可靠性,提出了跨层管理协议的设计方法。