一种提高B—树存贮利用率的有效算法

本文提出的算法有效地延缓了Ｂ－树生成过程中结点的分裂，与经典的Ｂ－树生成方法相比，不仅减少了组织和维护的开销，而且有效地提高了存贮空间利用率和检索效率。     

一种提高B—树贮利用率的有效算法

本文提出的算法有效地延缓了Ｂ－树生成过程中结点的分裂，与经典的Ｂ－树生成方法相比，不仅减少了组织和维护的开锁，而且有效地提高了存贮空间利用率和检索效率。     

Modbus/TCP协议事务调度的研究

介绍Modbus/TCP协议的事务处理模式在SCADA采集子系统中的应用,分析多事务调度的采集方式.研究表明,采用多事务异步调用技术的SCADA采集子系统具有较高的采集率,能够保证系统高效稳定运行.     

基于低功耗技术的无线A/D数据采集系统设计

对当前物联网技术及工业设备数据信息采集方式进行调查和分析.本系统采用滤波理论和算法,将所需采集的模拟信号转换为数字信号.使用STM8L系列单片机结合LoRa无线技术,实现数据低功耗、远距离的传输,同时在终端将数据实时存储到SD卡中,实现数据远程、连续、有序地采集.在数据传输方面设计了一套高效安全的数据传输协议,检测数据传输中的错误,保证通信系统的安全性.该系统有效实现低功耗远程A/D数据采集,通过高效安全的数据传输协议提高系统的可靠性,同时对采集数据进行实时存储,全面提高系统的性能.     

数据中心中路由编码的可行性研究

修复带宽最优并不代表修复通信量也是最优的,后者与物理网络拓扑有着密切联系.本文基于路由编码的思想减少修复通信量.首先,基于信息流图对物理网络中数据的传递过程进行建模,证明得出了满足路由编码可行的充要条件,并发现路由编码可以基于再生码实现.然后,针对数据中心网络设计的特点,为Fat-tree设计了一个工作在应用层的协议来生成修复树,为CamCube设计了一个启发式算法来生成修复树.关于最小存储再生码的数据修复过程的仿真实验表明,路由编码可以有效地降低修复通信量,2种修复树生成方案在各自适合的网络中均有较好性能：在帮助节点数较小时,Fat-tree和CamCube中的修复通信量分别降低了大约50%和30%.     

AXI标准协议在微型机载采集设备中的应用

本文介绍了AXI片内总线协议规范,指出了其高性能、高带宽、低延迟的特点.针对微型机载采集设备中FPGA设计的难点,本文提出了采用AXI标准总线协议作为采集系统FPGA控制逻辑的结构框架,使得整个采集系统的软件架构具有高度规范性和灵活性,同时兼顾了较高的性能需求,并取得了较好的实用效果.     

基于能量采集的全双工中继系统时隙优化

针对能量采集基础上的全双工中继系统时隙优化问题,以双跳能量采集全双工中继系统为模型,基于中继工作于时间分割模式,分析了在放大中继转发协议与译码中继转发协议下如何实现系统吞吐量最大化,对能量采集时隙进行了优化研究,推导了瑞利衰落信道下最佳能量采集时间的具体表达式,在仿真中对比了全双工中继系统与半双工中继系统的吞吐量。通过性能分析与仿真实现可知,全双工中继技术可以提高频谱利用效率、系统吞吐量,满足日益增长的高速率要求。     

基于IPVPN的无线网络监控系统

论述了基于GPRS网络的监控系统.监控终端由端采集控制和传输控制两部分组成,通过在单片机系统中嵌入相应的通信协议,经有线网络和无线网络将前端采集数据传输至监控中心,实现对现场的实时监控处理.该系统涉及GPRS网络技术、串口RS-232/RS-485传输协议、网络通讯协议、系统抗干扰电路设计等相关技术.     

基于嵌入式实验床(Testbed)的AODV协议研究

AODV协议是一种用于无线Ad Hoc网络的路由协议.笔者在Linux操作系统下实现了AODV路由协议,并以此为基础,搭建了一个无线Ad hoc网络的实验床(Testbed),并成功移植到以PowerPC处理器为核心的嵌入式平台上.在实验床的真实场景中,本文从路由性能的三个方面端到端的延迟、吞吐量、投递率对AODV路由协议进行了一系列实验和性能评价工作,并分析了Hello消息机制对网络性能的影响.在实验床的基础上,本文设计实现了嵌入式视频采集传输实验、异网互联实验与网络拓扑图形化显示实验.     

千兆网络数据包分析过滤采集系统设计

介绍了基于高性能FPGA的千兆网络数据分析过滤采集系统设计.该系统能够对千兆主干网的网络数据进行分析,过滤和采集.该系统提供良好的配置接口,并将所关心的数据转发,百分比采样或是抛弃.而且能够对报文进行统计,并按照协议类型,源地址,目的地址等规则将数据包分类存储起来.本系统采用硬件查找方式进行数据包的分类极大地加速了数据包分类的速度.     

Block acknowledgment: redesigning the window protocol

A window protocol based on the block acknowledgment method, in which acknowledgment message has two numbers, m and n, to acknowledge the reception of all data messages with sequence numbers ranging from m to n, is discussed. In the window protocol, message sequence numbers are taken from a finite domain and both message disorder and loss can be tolerated. An initial version of the protocol that uses a simplified timeout action and unbounded sequence numbers is presented, the simplified timeout action in the protocol is replaced by a sophisticated one without disturbing the protocol's correctness, and the unbounded sequence numbers are replaced by bounded ones while preserving the protocol's correctness. Remarks concerning other variations of the protocol are also presented     

Modified bundled-data as a new protocol for NoC asynchronous links

Asynchronous interconnection paradigm in NoCs has attracted many system designers in the recent years, through its different possible implementation strategies. In this paper, we present a new insight on how to categorize asynchronous protocols and explore a suitable protocol for the NoC asynchronous links. The new categorization criterion is based on the type of dependency between data transferring and handshaking tasks in a protocol. Furthermore, a new protocol called modified bundled-data (MBD) is introduced. MBD is a bundled-data-like protocol with two pairs of two-phase dual-rail encoded parity lines on the lateral sides of data lines, besides one two-phase acknowledgement line. The new protocol is evaluated by comparing its simulation results with those of bundled-data (BD) and dual-rail (DR) protocols on a 32-bit flit NoC asynchronous link. For this purpose, a new comprehensive interconnect model has been developed. The simulation results show that the new protocol's features such as power consumption, throughput, and latency are comparable with BD protocol's, while its signal integrity features are close to DR's.     

A reservation-based multicast protocol for WDM optical star networks

In this paper, we present a reservation-based medium access control (MAC) protocol with multicast support for wavelength-division multiplexing networks. Our system is based on the single-hop, passive optical star architecture. Of the available wavelengths (channels), one channel is designated as a control channel, and the remaining channels are used for data transmission. Each node is equipped with a pair of fixed transceiver to access the control channel, and a fixed transmitter and a tunable receiver to access data channels. For easy implementation of the protocol in hardware and for precisely computing the protocol's processing overhead, we give a register-transfer model of the protocol. We simulate the protocol to study its throughput behavior, and present its analytic model. For a node to be able to send data packets in successive data slots with no time gap between them, in spite of the situation that the protocol's execution time may be longer than data transmission time, we propose the idea of multiple MAC units at each node. Unicast throughput of our protocol reaches the theoretically possible maximum throughput for MAC protocols with distributed control, and the multicast throughput is at least as good as, and even better than, those delivered by existing MAC protocols with distributed control.     

DEED:一种无线传感器网络中高效节能的数据通信协议

无线传感器网络由许多具有低功率无线收发装置的传感器节点组成,能够有效地从不同环境监测收集周边环境信息并传送到远处的基站进行处理.由于传感器节点的电池能量极为有限,因此节点的通信应有效的利用能量,以延长网络的生命周期.LEACH^[4]协议是一种典型的能有效延长网络生命周期的节能通信协议.本文提出了一种分布的、高效节能的通信协议DEED,DEED利用了数据聚合技术,以聚类的方式组织节点,聚类首领在网络中均匀分布并组织成路由树,由根节点与基站直接通信.实验结果显示DEED性能远好于LEACH.     

Clustering perception mining of network protocol’s stealth attack behavior

Deep stealth attack behavior in the network protocol becomes a new challenge to network security.In view of the shortcomings of the existing protocol reverse methods in the analysis of protocol behavior,especially the stealth attack behavior mining,a novel instruction clustering perception mining algorithm was proposed.By extracting the protocol's behavior instruction sequences,and clustering analysis of all the behavior instruction sequences using the instruction clustering algorithm,the stealth attack behavior instruction sequences can be mined quickly and accurately from a large number of unknown protocol programs according to the calculation results of the behavior distance.Combining dynamic taint analysis with instruction clustering analysis,1 297 protocol samples were analyzed in the virtual analysis platform hidden disc which was developed independently,and 193 stealth attack behaviors were successfully mined,the results of automatic analysis and manual analysis were completely consistent.Experimental results show that,the solution is ideal for perception mining the protocol's stealth attack behavior in terms of efficiency and accuracy.     

Energy Minimization for Real-Time Data Gathering in Wireless Sensor Networks

This paper studies the challenging problem of energy minimization for data gathering over a multiple-sources single-sink communication substrate in wireless sensor networks by exploring the energy-latency tradeoffs using rate adaptation techniques. We consider a real-time scenario for mission-critical applications, where the data gathering must be performed within a specified latency constraint. We first propose an offline numerical optimization algorithm with performance analysis for a special case with a complete binary data gathering tree. Then, by discretizing the transmission time, we present a simple, distributed on-line protocol that relies only on the local information available at each sensor node. Extensive simulations were conducted for both long and short-range communication scenarios using two different source placement models. We used the baseline of transmitting all packets at the highest speed and shutting down the radios afterwards. Our simulation results show that compared with this baseline, up to 90% energy savings can be achieved by our techniques (both off-line and on-line), under different settings of several key system parameters     

The effects of on-demand behavior in routing protocols for multihopwireless ad hoc networks

A number of different routing protocols proposed for use in multihop wireless ad hoc networks are based in whole or in part on what can be described as on-demand behavior. By on-demand behavior, we mean approaches based only on reaction to the offered traffic being handled by the routing protocol. In this paper, we analyze the use of on-demand behavior in such protocols, focusing on its effect on the routing protocol's forwarding latency, overhead cost, and route caching correctness, drawing examples from detailed simulation of the dynamic source routing (DSR) protocol. We study the protocol's behavior and the changes introduced by variations on some of the mechanisms that make up the protocol, examining which mechanisms have the greatest impact and exploring the tradeoffs that exist between them     

基于状态相关字段识别的未知二进制协议状态机逆向方法

协议状态机逆构技术是分析未知协议行为逻辑的基本方法,是网络安全、信息对抗领域的一个重要研究方向。针对截获的未知二进制协议的通信数据,提出了一种二进制协议状态机逆向方法,该方法能够根据通信数据逆构协议状态转移图。在该方法中,设计了针对通信数据帧的基于多序列比对的对应字段对齐算法以及基于字段统计量分析的协议状态相关字段提取算法,并根据提取出的协议状态相关字段构建状态转换模型。在地址解析协议( ARP)和传输控制协议( TCP)上的实验结果表明该方法能够有效逆构出协议的状态转换模型。     

WSN中一种基于延迟限定的数据收集算法

数据收集是无线传感器网络研究中的一个关键问题,目前基于树的数据收集方法经常会造成节点负载不均衡、树的高度无法控制等问题,从而使得数据收集延迟加大。针对该问题提出了一个新的算法——基于延迟限定的数据收集算法(DBDG),该算法从一棵最少跳数树(Fewest Hops Tree,FHT)出发,迭代地选择网络中的一条边加入树,通过限定树的高度来满足延迟限定,然后通过使树上"瓶颈节点"的度最小化来延长树的生命周期。仿真实验表明,与目前已有的协议相比,DBDG能在限定的高度内构造生命周期更长的生成树。     

An Energy-Efficient and Collision-Avoidance MAC Protocol with Pre-scheduling for Wireless Sensor Networks

In this paper, we propose energy efficient MAC protocols for data gathering tree structure. The basic concept of the proposed protocol is that it reduces traffic overloads in low depth nodes by introducing full sleep state for one frame. To maximize network performance, we only control traffic from non-relay nodes which are leaf nodes in the tree. We introduce a new superframe structure for pre-scheduling to alleviate contentions and packet collisions between children nodes. In addition, leaf nodes go into a full sleep mode for one superframe in heavy traffic loads by using control packets, which results in a considerable reduction of energy consumption at low depth nodes. Simulation results show the proposed protocol saves more energy and achieves better packet delivery ratio compared to the DMAC with a moderate increase of a latency performance.