P2P网络流媒体关键技术

P2P网络流媒体技术一直是学术界和产业界的研究热点.本文围绕覆盖网络拓扑结构,对现有的P2P流媒体系统作了全面的归类总结,深入介绍和分析了覆盖网络构建、数据块调度策略等P2P流媒体核心技术,并概要讨论视频编码、网络编码、覆盖网络拓扑优化、安全与激励机制等P2P流媒体相关增强技术.对典型P2P流媒体系统的性能进行了比较,...     

P2P技术

本文简要介绍了P2P技术的实现原理.文章以对SKYPE软件进行黑盒分析的结果为基础,深入剖析了SKYPE的实现技术,包括网络结构、呼叫接续、被叫寻址以及语音编码等各方面.对研究P2P语音技术的人员有一定的参考价值.     

网络编码在P2PB网络中的应用

网络编码是信息论领域的一个重要突破,它不同于信源编码和信道编码,将网络编码应用到P2P网络中是当前研究热点之一,其中具有分布式特点的随机网络编码可厂泛应用于P2P网络.对具有非买时性的P2P文件下载应用,为降低随机网络编码引入的复杂性,可对文件分块进行分代,然后采用代内或代间网络编码技术.对具有实时性的P2P流媒体直播和点播,则需要采用具有优先级意识的网络编码技术,包括分层网络编码,或与推拉技术相结合来实现高效率的P2P流媒体分发.     

网络编码在P2P网络中的应用

网络编码是信息论领域的一个重要突破,它不同于信源编码和信道编码,将网络编码应用到P2P网络中是当前研究热点之一,其中具有分布式特点的随机网络编码可广泛应用于P2P网络。对具有非实时性的P2P文件下载应用,为降低随机网络编码引入的复杂性,可对文件分块进行分代,然后采用代内或代间网络编码技术。对具有实时性的P2P流媒体直播和点播,则需要采用具有优先级意识的网络编码技术,包括分层网络编码,或与推拉技术相结合来实现高效率的P2P流媒体分发。     

基于移动P2P网络的Mobile TV的实现方案

Mobile TV已经成为人们广泛关注的增值业务之一。本文提出一种基于移动P2P（Mobile P2P，MP2P）技术的Mobile TV业务的实现方式，为了能更好地支持多种类型的移动终端，在网络中加入编码变换服务器，提供实时视频编码变换功能。     

网络编码在P2P流媒体播放系统的应用

P2P流媒体系统近年来发展非常迅速,显示了巨大的生命力,但是另一方面现有的P2P流媒体系统又存在很多问题：文件定位技术、节点选择技术、网络不稳定性及网络带宽等等。大量的理论研究表明,网络编码可以提高系统的稳定性,提高网络带宽的利用率,而SIP协议可以有效控制和管理P2P网络。文章将网络编码和SIP协议应用到P2P流媒体系统中,目的是解决现有P2P流媒体系统的普遍问题。试验结果表明,应用网络编码技术和SIP协议的P2P流媒体播放系统,在网络健壮性、播放质量、网络资源利用率等方面都有良好的改善。     

基于移动P2P网络的移动电视的实现方案

移动电视（Wobile TV）已经成为人们广泛关注的增值业务之一。本文提出一种基于移动P2P（Mobile P2P，MP2P）技术的移动电视业务的实现方式，为了能更好地支持多种类型的移动终端，在网络中加入编码变换服务器，提供实时视频编码变换功能。[编者按]     

基于Java语言P2P结构的网络视频会议系统

随着信息技术和网络技术的飞速发展以及人们的应用需求,产生了网络视频会议系统.针对P2P网络技术协同网络会议系统的需求,分析流媒体传输与控制技术、Java Media Framework （JMF）媒体框架技术、RTP/RTCP流媒体传输与控制协议、P2P结构分析和P2P工作原理,建立P2P结构的系统框架和基于时间戳的RTCP流媒体同步机制,设计了基于JMF类及P2P结构的网络视频会议系统.     

基于P2P的僵尸网络及其防御

 僵尸网络作为网络犯罪活动的平台,正朝着P2P等分布式结构发展.研究僵尸网络的发展方向以及构建技术,有助于我们全面地了解僵尸网络活动的特点,从而更好地开展僵尸网络的检测和防范研究.本文分析了攻击者的需求,提出了一种基于层次化P2P网络技术的新型僵尸网络结构,并对这种僵尸网络的可行性和具体的传播、通讯、控制等各个方面进行了深入分析和探讨.在此基础上,我们通过模拟实验对各种防御策略的有效性进行了分析和评估,实验数据表明,在考虑实际可操作性条件下,现有的防御策略难以有效摧毁P2P结构僵尸网络.最后,我们讨论了这种新型僵尸网络可能的防御方法.     

P2P相关技术的研究

对等网络（P2P）是一种构筑于底层通信网络基础设施之上的虚拟网络,是一个分布式的、具有互操作性的自组织系统。现在,运用P2P技术的软件比比皆是,使人们在不知不觉中感受到了P2P技术带来的快乐,与此同时它也浪费了大量的网络带宽。为了让P2P系统更高效的运行,同时降低网络的流量,本文介绍了P4P技术的相关理论。通过对P2P技术的研究,指出了P2P应用与网络运营商之间的矛盾,并对其解决办法进行了详细的分析。     

Efficient P2P-based mutual authentication protocol for RFID system security of EPC network using asymmetric encryption algorithm

Internet of Things (IoT) is a new vision of the future technological ubiquity in ubiquitous computing, which becomes the mapping from the real world to the digital one. Radio frequency identification (RFID) technology is a key enabler of the future IoT and it has a great economical potential. However, the RFID system uses of Electronic Product Code (EPC) tags can drastically threaten the security of applications. With the widespread use of RFID technology, its security problems become the hot topic in the academic and industrial fields. Aiming at the RFID network's security problems, we propose a novel P2P based RFID network architecture (P2P-RFID), and analyze the security problems in this kind of network. And a feasible and scalable protocol to guarantee P2P-RFID network security is also presented in this paper. The proposed protocol uses P2P storage technology together with the utilizing of asymmetric encryption algorithm (RSA) based authentication. An analysis proves that the presented protocol is secure. Moreover, the protocol authentication does not require a Certificate Authentication (CA) database, which avoids the single-point bottleneck.     

频率漂移的RFID冲突标签的物理层恢复

在无线射频识别（RFID）系统中,物理层上恢复冲突标签可有效提高系统识别效率.然而在超高频（UHF） RFID系统中,频率漂移是一普遍现象,它对物理层的冲突标签恢复有一定的影响.本文针对频率漂移的标签冲突恢复问题,采用径向基函数（RBF）网络分离算法对冲突信号分离,并利用FM0电平边沿跳变的原理实现解码,以此实现冲突标签信号恢复.实验结果表明,当发生频率漂移时,本文的方法在误码率和分离效率上均优于传统算法.     

RFID标签中有机补偿电路的设计

当前RFID标签技术有着极为广泛的应用,为了减少RFID标签的制造成本和提高工作的可靠性,提出了一种有机补偿电路。该电路集成了8个阶段的有机整流器,其最高工作频率可以达到14 MHz,以及一个集成的PUF结构,它产生一个不可克隆的随机码,每一个独立的结构生成自己的代码,并可以准确地从其他电路中识别出来,耦合这两个电路以及天线将可以建立一个RFID无源标签。该方案可以应用于塑料薄膜中逐片有机处理的RFID标签中,方便设计和制造出复杂的全有机电路。     

Hands On

This paper discusses the idea of a hobbyist having a radiofrequency identification (RFID) tag implanted in him. In an RFID "lock" system, each RFID tag, which is essentially a minitransmitter, sends out a sequence of radiofrequency pulses representing a unique number, usually 10 to 16 digits in length. An RFID tag's memory typically ranges from a few bits to 128 bits, in the common ISO-compliant tag, to several megabytes. There are 6 ways on how an RFID implant works:1) It emits radio waves, which powers the implanted tag when it si within range, 2) the tag, which consists of a microchip and an antenna, checks the password, 3) It transmits a code stored in its memory back to the reader, 4) the reader compares the tag's code to a key code stored in the reader, 5) the reader generates a new and stores it, then sends the new key to the tag, and 6) the tag writes the new key into its memory     

RFID系统中信息保密机制研究与设计

随着RFID技术应用的不断扩展和深入,RFID系统面临的安全问题也越来越引人关注,而且RFID要广泛应用于商业就必须要解决其在信息保密和信息隐私泄露等方面面临的安全挑战。在总结分析现有RFID系统所面临的信息保密和信息隐私保护等安全问题的基础上,提出了一种增强信息隐私保护和防泄密的RFID系统安全机制,并讨论了有关具体实现。文中所提出的方法可有效抵抗信息传输中的内容窃听、重放攻击,以及对目标的隐私跟踪等问题。     

手持式RFID读写器网络接口设计

为适应RFID读写器在不同应用系统中的要求,开发了一种以MSP430F149单片机为核心的具有嵌入式以太网网络接口的手持式RFID读写器。文中介绍RFID读写器中单片机与以太网控制器RTL8139组成的网络接口设计方法,实现了手持式RFID读写器接入Internet网络进行数据通信。     

RFID系统读写器与电子标签硬件结构分析

射频识别(RFID,Radio Frequency Identification)是一种非接触式的自动识别技术,也称为"无线条形码",射频识别以非接触性、识别速度快、可以多卡识别等优于其他自动识别技术的特性受到广泛重视。应用非常广泛,如动物识别、门禁控制、生产线自动化控制、停车场管理、物料管理等等。对RFID系统的工作原理进行了介绍,重点分析了读写器硬件结构,电子标签硬件结构,希望对RFID系统的开发有所帮助。     

An Efficient Reader Anticollision Algorithm in Dense RFID Networks With Mobile RFID Readers

In parallel with the proliferation of radio-frequency identification (RFID) systems, many RFID readers have been increasingly employed. In such an environment, collision among readers becomes a serious problem. Existing anticollision algorithms, depending on the information of neighboring readers, may require constant effort in order to grasp such information. Although it may be given by a server or a coordinator, they may not be suitable in dense and dynamic RFID networks with mobile readers. In this paper, we propose an efficient reader anticollision algorithm using a polling server in dense and dynamic RFID networks with mobile readers. Owing to the assistance of the server, the readers can rapidly decide whether they can work or not without interfering neighbors and can be easily synchronized. Our proposed algorithm is simple and makes readers aware of neighbors to minimize reader collisions. Performance evaluation shows how many readers can operate in a network and indicates that our proposed algorithm is more efficient than distributed color selection, colorwave, and hierarchical Q-learning algorithm, particularly in dense and mobile environments.      

Instant collision resolution for tag identification in RFID networks

In this paper, we approach the problem of identifying a set of objects in an RFID network. We propose a modified version of Slotted Aloha protocol to reduce the number of transmission collisions. All tags select a slot to transmit their ID by generating a random number. If there is a collision in a slot, the reader broadcasts the next identification request only to tags which collided in that slot. Besides, we present an extensive comparative evaluation of collision resolution protocols for tag identification problem in RFID networks. After a quick survey of the best performing RFID tag identification protocols, both deterministic and probabilistic, we present the outcome of intensive simulation experiments set up to evaluate several metrics, such as the total delay of identification process and the bit complexity of reader and tags. The last metric is strictly related to energy constraints required by an RFID system. The experiments point out that our protocol outperform all the other protocols in most cases, and matches them in the others.     

Novel Trusted Hierarchy Construction for RFID Sensor–Based MANETs Using ECCs

In resource‐constrained, low‐cost, radio‐frequency identification (RFID) sensor–based mobile ad hoc networks (MANETs), ensuring security without performance degradation is a major challenge. This paper introduces a novel combination of steps in lightweight protocol integration to provide a secure network for RFID sensor–based MANETs using error‐correcting codes (ECCs). The proposed scheme chooses a quasi‐cyclic ECC. Key pairs are generated using the ECC for establishing a secure message communication. Probability analysis shows that code‐based identification; key generation; and authentication and trust management schemes protect the network from Sybil, eclipse, and de‐synchronization attacks. A lightweight model for the proposed sequence of steps is designed and analyzed using an Alloy analyzer. Results show that selection processes with ten nodes and five subgroup controllers identify attacks in only a few milliseconds. Margrave policy analysis shows that there is no conflict among the roles of network members.