Novel satellite transport protocol with on-board spoofing proxy

As a result of the exponential growing rate of worldwide Internet usage, satellite systems are required to support broadband Internet applications. The transmission control protocol （TCP） which is widely used in the Internet, performs very well on wired networks. However, in the case of satellite channels, clue to the delay and transmission errors, TCP performance degrades significantly and bandwidth of satellite links can not be fully utilized. To improve the TCP performance, a new idea of placing a TCP spoofing proxy in the satellite is considered. A Novel Satellite Transport Protocol （NSTP） which takes advantage of the special properties of the satellite channel is also proposed. By using simulation, as compared with traditional TCPs, the on-board spoofing proxy integrated with the special transport protocol can significantly enhance throughput performance on the high BER satellite link, the time needed to transfer files and the bandwidth used in reverse path are sharply reduced.

ARROW-WTCP:A fast transport protocol based on explicit congestion notification over wired/wireless networks

An explicit congestion notification (ECN)-based distributed transport protocol,ARROW-WTCP (AcceleRate tRansmission towards Optimal Window size TCP for Wireless network),was proposed.The ARROW-WTCP enables feasible deployment of ARROW-TCP from wired to wireless networks by providing a joint design of source and router algorithms.The protocol obtains the actual capacity of the wireless channel by calculating the queue variation in base station (BS) and adjusts the congestion window by using the feedback from its bottleneck link.The simulation results show that the ARROW-WTCP achieves strong stability,max-min fairness in dynamic networks,fast convergence to efficiency without introducing much excess traffic,and almost full link utilization in the steady state.It outperforms the XCP-B (eXplicit Control Protocol Blind),the wireless version of XCP,in terms of stability,fairness,convergence and utilization in wireless networks.

A Feedback Scheme for Fountain Codes Based Transport Protocol in Space Communications

This paper proposed a practicalfeedback scheme for fountain codes based transportprotocol in space communications. In the proposed scheme,the sender is signaled by two types of acknowledgment(ACK) packets.Before decoding, packet loss probability isestimated on the receiver side and encapsulated intoa soft ACKand sent to the sender.After decoding,decoding results are encapsulated into hard ACKsandsent to the sender.There are two contributions in the proposed scheme: 1. Employing physical layer calculation instead of application layer statistics to estimate the packet loss probability of space channel, which can improvethe accuracy and practicality. 2. A cascade overhead-failure probabilityrelationship between the sender and the receiver has been analyzed to help determine the exact numberof packetsneeded byfountain decoding.Simulations show that for space communications,compared with the existing space transport protocols, fountain codes based transport protocolwith the proposed schemecan not only ensure transmission reliability, but also greatly improvelink utilization.

Energy-Efficient and Reliable Transport Protocols for Wireless Sensor Networks: State-of-Art

New wireless sensor network applications (e.g., military surveillance) require higher reliability than a simple best effort service could provide. Classical reliable transport protocols like Transmission Control Protocol (TCP) are not well suited for wireless sensor networks due to both the characteristics of the network nodes (low computing power, strong energy constraints) and those of the main applications running on those nodes (low data rates). Recent researches present new transport protocols for wireless sensor networks providing various type of reliability and using new mechanisms for loss detection and recovery, and congestion control. This paper presents a survey on reliable transport protocol for WSNs.

A Transport Protocol and Its Formal Description for Local Networks

This paper discusses a transport protocol and its formal description techniques for local network. The transport layer function, the transport services and a transport protocol design in a local network architecture model are presented. A transport protocol specification using the finite state automata (FSA) is given. The correctness of the protocol is verified by using the reachability tree technique with respect to the protocol properties of completeness, deadlock and livelock freeness, termination and reachability.

Implementation and Evaluation of Transport Layer Protocol Executing Error Correction (ECP)

Technologies for retransmission control and error correction are available for communications over the Internet to improve reliability of data. For communications that require the data reliability be ensured, TCP, which performs retransmission control, is often employed. However, for environments and services where response confirmation and retransmission are difficult, error correction technologies are employed. Error correction is generally implemented on UDP, but the existing framework implemented on UDP frequently does not consider the maximum frame size of the data link layer and relegates data division to the IP module. The IP module divides data according to the maximum size for the data link, and the receiving IP module reconstructs the divided data. For a data link layer typified by the current Ethernet with an error detection function, the frame is often destroyed upon error detection. At the IP module, the specification allows destruction of the entire dataset whenever divided data necessary for reconstruction is incomplete. Consequently, an error in a single bit results in a total loss of data handed to the IP module, and thus error correction performance declines with the increase in data size handed to the IP module. The present study considers the MTU of the data link layer and proposes error correction protocol (ECP) over IP, which decreases the transfer data volume flowing to the data link layer by dividing data into blocks of appropriate size based on designated error correction code and its parameters (thus improving error correction performance) and assesses the performance of ECP. Experimental results demonstrate that performance is comparable or better than existing error correction frameworks. Results also show that when a specification not ensuring the reliability of the data link layer was employed, error correction was superior to existing frameworks on UDP.

区块链网络综述

区块链是典型的分布式系统,底层网络的性能和安全性至关重要.区块链网络的本质是P2P网络,然而在安全模型、传输协议和性能指标等方面与传统P2P网络存在明显差异.首先,针对区块链网络的传输流程进行全面、深入地分析,阐明区块链网络所面临的瓶颈挑战.其次,针对区块链网络拓扑结构和传输协议的最新研究工作,从节点异构性、编码方案、广播算法和中继网络等方面系统性地分类梳理,并归纳总结跨链网络实现和网络仿真工具.最后,探讨区块链网络的未来研究趋势.

基于信息熵与服务器识别的DoH流量检测

DNS over HTTPS(DoH)协议是一种针对域名系统(DNS)的最新改进方案,然而用户可使用第三方DoH服务规避内网原有的监管,所以异常流量检测方法不再适用于检测DoH流量。针对该问题提出了一种DTESI算法。首先,基于信息熵将DoH流量作为异常流量从全部网络流量中筛选出来;然后,利用DoH服务器与同一客户端建立TLS连接时响应方式总是相同的特性,用指纹识别检测客户端与DoH服务器之间的TLS协商,确定DoH服务器身份;最后,使用Top-K抽样算法选出一定时段内网络中前K台活跃主机着重进行流量检测,使算法能应用于中大型组织的网络。实验结果表明,针对发现的异常流量,DTESI算法检测出的DoH服务提供商准确率超过94%。在此基础上比较了在不同K值下的算法检测时间和对网络中全部DoH流量的检测覆盖率,结果表明合理选择K值可以提升算法的整体效能。

铜与卵巢癌的研究进展

卵巢癌是常见的妇科恶性肿瘤之一,多数患者在发现时已是晚期,治疗效果及预后差,严重影响患者的生存质量。铜是人体内重要的微量元素,参与多种关键生物过程,并与多种恶性肿瘤的进展密切相关。目前,越来越多的研究探索了铜与卵巢癌的关系,发现卵巢癌患者血浆、腹水及肿瘤组织中铜水平较健康人群明显升高,并且多种铜转运蛋白的异常表达与卵巢癌铂类药物化疗耐药密切相关。近年来,针对铜代谢的抗肿瘤治疗方式成为了研究的热点,大量的研究证明了铜螯合剂和铜离子载体在体内外对卵巢癌的显著抑制作用。综述铜与卵巢癌的密切关系,深入了解基于铜代谢的药物及治疗方法在卵巢癌中的应用,以期为卵巢癌的治疗提供新的方向。

基于MQTT协议的物联网岸电监控系统

目前港口岸电系统地域分布较广且供电运行数据无法及时掌握。针对这一问题,设计并开发一种基于MQTT协议的物联网岸电监控系统,利用前端数据采集装置对供电系统的供电运行参数、用户信息、电力信息、设备状态等数据进行实时采集,经过数据处理和封装打包后,采用移动4G模块将封装好的数据通过MQTT协议上传至云端服务器,数据传输采用MD5数据加密算法,实现前端数据采集设备和监控系统之间的可靠数据通信,实时监控岸电系统运行状态,同时利用手机App对岸电系统参数进行实时监控与参数修改,增强物联网岸电监控系统的灵活性和便捷性。

基于地理位置的流量感知辅助路由协议

为解决车载自组织网络(VANETs)中拓扑空洞、链路冗余、链路稳定性差、路由表维护成本高等问题,提出一种基于地理位置的流量感知辅助路由协议(TAR)。通过对车辆信息流量及链路稳定性的评估进行分析和建模,获取链路收益和有效信息流量。利用多属性效用理论(MAUT),使用加权链路收益和有效信息流量计算车辆效用值并作为路由选择的依据。根据节点相对位置信息,动态切换数据转发模式,提高链路稳定性。实验结果表明,与GPSR和MM-GPSR协议相比,TAR能够有效减少路由冗余,分组交付率提高15%,延迟降低40%。

基于Stacking与多特征融合的加密恶意流量检测

加密技术保护网络通信安全的同时,大量恶意软件也采用加密协议来隐藏其恶意行为。在现有基于机器学习的TLS加密恶意流量检测模型中,存在单模型检测算法对多粒度特征适用性差和混合流量检测误报率高的问题。提出基于Stacking策略和多特征融合的非解密TLS加密恶意流量检测方法。分析加密恶意流量特征多粒度的特点,提取流量的流特征、连接特征和TLS握手特征。对所提取的特征通过特征工程进行规约处理,从而减少计算开销。对规约处理后的3类特征分别建立随机森林、XGBoost和高斯朴素贝叶斯分类器模型学习隐藏在流量内部的规律。在此基础上,使用流指纹融合处理后的多维特征,利用Stacking策略组合3个分类器,构成DMMFC检测模型来识别网络中的TLS加密恶意流量。基于CTU-13公开数据集对构建的模型进行性能评估,实验结果表明,该方法在二分类实验上识别召回率高达99.93%,恶意流量检测的误报率低于0.10%,能够有效检测非解密的TLS加密恶意流量。

基于电网信息模型数据的共享与高效传输技术研究

随着电网数据的快速增长以及通信技术的发展,新型电力系统对数据传输的实时性与共享性有了更高的要求。针对这一问题,文中在电网信息模型的基础上设计了一套数据共享与高效传输的技术方案。该方案基于建立规范的电网信息模型来提取电信号的物理特征,并利用信号辨识算法获取信息的特征参量,再通过解析与拟合实现数据的分析及还原。同时使用ASN编码规则对信息进行动态编码,且数据链路层采用ISO生成标准数据帧,从而有效增强了数据传输的实时性。通过搭建仿真平台对电网信息模型进行数据传输分析测试,对比测试的结果验证了所提传输技术方案具有良好的共享性能,且传输效率较高。

图书馆数字资源统计系统建设研究

为获取有效且可分析的数字资源使用数据,解决当前图书馆依赖数据库商提供统计数据的困境,文章在分析数字资源统计系统实现原理与应用、国内外数字资源统计标准的基础上,结合首都师范大学图书馆馆藏资源情况提出数字资源统计系统的指标和功能需求,以此提出系统构建的总体框架和功能模块。

网络链路传输层数据分组加密算法仿真

为了更好的实现网络数据保护,提出网络链路传输层数据分组加密优化算法。构建网络链路信息传输模型,并在模型的基础上对GBNARQ协议及其协议性能展开学习;针对链路传输层的数据开展RSA加密,并分析其自身所具备的安全问题,叠加MD5签名机制,以实现网络链路传输层数据分组加密算法优化的目的。经实验验证表明,所提方法对硬件内存要求较小,在计算过程中的能量消耗较少,在数据量相同的情况下所提方法的加密效率最高,且通过所提方法加密后,数据ASCII分布图分布均匀,使得该方法具有较高的安全性能。

采集设备接入的框架设计与实现

随着嵌入式技术和网络通信技术的快速进步,物联网近些年来也有很大的发展,大量不同类型的终端设备都需要接入到网络中。但整个物联网结构从物理层、网络层再到应用层,每层之间采用不同的通信协议,这大大增加了集成系统实现的困难。提出一种支持自定义协议、多种终端设备的物联网接入框架的设计方案,并据此研制软件系统。通过自定义协议接入不同的设备,增强系统的扩展性和互操作性,并可以灵活处理设备的数据与事件。

Semi-TCP与ARQ联合的端到端可靠传输方法

在无线自组织网络中,数据传输受干扰较多,信道不稳定,因此传统的TCP协议并不能满足在这种复杂环境下的通信要求,节点间的自动重传请求协议(ARQ)重传增加,会导致节点的缓存占用率很大,整体传输性能降低。为了解决该问题,采用Semi-TCP协议与ARQ协议相结合,在不改变原有TCP架构的基础上将拥塞控制下放到链路层,改变链路层ARQ的纠错能力,提高信道的利用率。在Exata平台上进行了仿真,实验证明在无线多跳网络中,该方法能有效提高网络传输性能。

RTP流音频回放技术在400 MHz数字列调系统中的应用

介绍DRTD系统中无线列调语音业务的音频回放技术。DRTD系统有线通信基于SIP协议和R T P流进行音频传输,通过混音、加窗语音检测、缓存、格式转换、信令控制等处理流程,将音频流在无线空口上进行传输,并最终在移动终端上实现语音波形回放,从而桥接无线列调中的有线通信和无线通信,为DRTD系统的核心业务提供支撑。

浅析西藏广播电视台高清制播系统中的数据通信技术

阐述西藏广播电视台高清制播系统中高清虚拟演播室的传感器数据通信、高清播出系统录像机控制通信、制作网与播出系统间通信所采用的技术。