基于数据包长度的网络隐蔽通道

在传统隐蔽通道模型的基础上,利用数据包的长度域,设计一种基于数据包长度的网络隐蔽通道模型(LAWB模型),给出其形式化描述。对该模型进行了分析,并分别在IPv4和IPv6上对该模型进行了实验。     

一种基于通道的AVISPA扩展方法研究

针对AVISPA工具在分析某些消息需要依靠具有特定属性的信道传递的安全协议或服务中存在的问题, 提出了一种基于抽象通道的扩展方法。抽象通道具有相关的安全性质保证如认证性, 能够对提供安全性质保证的底层服务建模, 并基于密码机制和标签等实现了抽象通道。利用扩展后的AVISPA工具分析有无消息源认证机制的Diffie-Hellman密钥交换协议的安全性, 表明了方法的有效性, 并且能够简化协议建模过程和增强AVISPA工具协议描述分析能力。     

基于部分广播通道的可验证秘密共享方案

借鉴Amos方案中重构秘密的思想对Rei方案进行了完善,提出一种基于部分广播通道的可验证秘密共享方案.在该方案的秘密分发阶段,秘密分发者与参与者之间使用部分广播通道进行通信,秘密重构阶段使用广播通道进行通信.该方案可处理不诚实秘密分发者与参与者情况,具有可验证性.通过对该方案的分析可知,该方案的通道数和总的通信量比已知的两个方案具有明显的优势.此外,该方案中各参与者的秘密份额可反复使用.     

网络隐通道的处理方式

本文首先介绍了网络隐通道的概念,讨论了在网络通信中隐通道存在的技术基础和实现原理,对基于网络通信协议的隐通道技术进行了深入分析。在此基础上讨论了隐通道技术的发展趋势并从网络安全的角度给出了对网络通信中隐通道的防范措施。     

面向STD标准的信号通道控制模型研究

IEEE 1641（STD）标准是IEEE标准委员会制定的新一代面向信号测试标准。首先对STD标准定义的连接及其动态模型进行了分析,梳理了常用的开关类型。接下来,提出了信号通道系统的描述模型和控制模型,并针对常用的多路开关和矩阵开关,给出了开关能力描述模型和开关组件接口定义,总结了资源管理器的工作步骤和虚拟连接的资源共享判断准则。最后,给出了该信号通道模型的实现方法,并通过开发的一个图形化信号通道系统管理软件,简化了用户的开发工作。     

磁臂隐通道的分析与研究

介绍了磁臂隐通道的形成机制,分析了它的存储隐通道、时间隐通道特征,并研究了消除（或降低）磁臂隐通道带宽的方法。     

基于链路分析法的复合隐蔽通道检测

在研究隐蔽通道的检测方法时,可以将隐蔽通道分成两大类：单一隐蔽通道和复合隐蔽通道。复合隐蔽通道具有了跨越多主机的特点,简单的主机入侵检测体系结构很难对此进行检测,而数据融合技术可以有效地解决这个问题。文中提出了基于数据融合思想的链路分析法,并对复合隐蔽通道的特点、链路分析法检测复合隐蔽通道的理论以及软件的设计进行描述。     

关于Photoshop通道技术在中职教学中的应用探讨

通道的概念是Photoshop的核心概念之一,需要对其有着全面深入的掌握,才能很好的应用Photoshop中的各种技术,用于实践的操作。本文将根据对通道技术的详细阐述,分析其概念分类和具体的应用等内容,并结合在中职计算机平面设计专业的教学应用,来进一步的加强对此概念的理解和掌握,力求以实际的操作例子,使中职生可以更加全面的领会这项核心的技术,并且逐渐的在实际的操作当中加以运用和完善。     

基于特征通道建模的目标检测方法

针对直接利用多尺度融合特征图进行目标检测时鲁棒性较差的问题,提出一种对图像全局信息进行多维建模的检测方法。采用多阶段的特征复用和特征融合减少特征间相关性损失,设计广度通道建模分支（BCMB）与深度通道建模分支（DCMB）弥补因感受野变化造成的图像空间信息不足,并丰富图像中各个目标间的上下文信息。通过BCMB建立宽高方向的二维通道矩阵,对多层级的感受野进行建模,进而丰富模型对图像的空间感知,完成目标定位。使用DCMB建立深度方向的一维通道向量,提炼图像的全局特征,丰富模型对图像的上下文描述,完成目标分类。将2个分支生成的通道图与输入特征进行加权融合,增强图像通道表达力,使输出的特征对目标的位置和类别信息更敏感。在PASCAL VOC 2007测试数据集上的实验结果表明,该方法的mAP值为85.8%,与未使用通道建模的Baseline方法相比,最高可提升3.2个百分点。     

基于WSN的智能雷场通道检测算法研究

以网络化、智能化为特征的第四代智能雷场系统是现代地雷发展的必然趋势。美国等发达国家10年前就开展了网络化智能雷场的研制工作,并已经初步列装部队。针对基于无线传感器网络的智能雷场的通道检测问题进行研究,建立了雷场网络化模型,定义了雷场内部通道和边缘通道的概念,并证明雷场中存在通道是机动车辆可以通过雷场的必要条件。同时设计了两种通道的检测算法,为网络化智能雷场的通道检测以及后续的雷场自愈提供了理论基础和技术实现途径。     

Hadamard quantum broadcast channels

We consider three different communication tasks for quantum broadcast channels, and we determine the capacity region of a Hadamard broadcast channel for these various tasks. We define a Hadamard broadcast channel to be such that the channel from the sender to one of the receivers is entanglement-breaking and the channel from the sender to the other receiver is complementary to this one. As such, this channel is a quantum generalization of a degraded broadcast channel, which is well known in classical information theory. The first communication task we consider is classical communication to both receivers, the second is quantum communication to the stronger receiver and classical communication to other, and the third is entanglement-assisted classical communication to the stronger receiver and unassisted classical communication to the other. The structure of a Hadamard broadcast channel plays a critical role in our analysis: The channel to the weaker receiver can be simulated by performing a measurement channel on the stronger receiver’s system, followed by a preparation channel. As such, we can incorporate the classical output of the measurement channel as an auxiliary variable and solve all three of the above capacities for Hadamard broadcast channels, in this way avoiding known difficulties associated with quantum auxiliary variables.     

Channel dynamic adjustment in data broadcast

Data broadcasting has become the preferred method to dispense data to a large number of mobile users. Current researches on on-demand data broadcast mainly propose algorithms based on a single broadcast channel or fixed multi-channel, i.e., fixed channel model. As a result of the dynamic diversity of data characteristics and client demands, the fixed channel model faces significant challenges in parallel broadcast diverse data. Further, the dynamic adjustment of the broadcast channel (dynamic channel model) based on client requests is favorable to service quality because it determines the number and sizes of channels that adapt to client demand in real-time. However, the dynamic channel model has not yet been thoroughly investigated for on-demand wireless data broadcasts. Accordingly, in this paper, a channel dynamic adjustment method (CDAM) is proposed. The innovations behind CDAM lie in three aspects. First, a data item priority evaluation and selection algorithm (S-RxW/SL) is proposed for evaluating the priority of data items and selecting the high priority data items to be considered in a broadcast cycle. Second, a weight and size average cluster algorithm (WSAC) is proposed for mining data item characteristics and clustering them. Third, based on the clustering results of WSAC, a channel splitting and data allocation algorithm (CSDA) is proposed for dynamically splitting the channel and allocating data items to the corresponding sub-channel. We compare the proposed method with some state-of-the-art scheduling methods through simulation. The theoretical findings and simulation results reveal that significantly better request loss rate (LR) can be obtained by using our method as compared to its alternatives.     

一种新的异步广播通信系统物理层设计

基于Turbo喷泉码和小波包分形调制技术，提出一种新的异步广播通信系统FPGA实现方案。系统用并行信源信道Turbo喷泉码实现无损数据压缩和纠错，小波包调制实现发送信号时频图样的自由铺砌。系统可以同时实现接收机的异步接入、单向信道下数据的可靠分发及信源信道联合编码，仿真表明该系统相对普通信源信道编码调制有较大性能改善。     

基于哈夫曼树的无证书公钥广播加密方案

现有的无证书广播加密方案是向用户传输相同的信息量,没有权限的概念。基于哈夫曼树,引入权值,提出了一种新的无证书公钥广播加密方案,实现了对不同权限的用户传输不同的信息量。与已有的广播方案相比,该方案平均计算密钥量少,降低了通信开销,灵活性更高。     

Semantic Access to Multichannel M-Services

M-services provide mobile users wireless access to Web services. In this paper, we present a novel infrastructure for supporting M-services in wireless broadcast systems. The proposed infrastructure provides a generic framework for mobile users to look up, access, and execute Web services over wireless broadcast channels. Access efficiency is an important issue in wireless broadcast systems. We discuss different semantics that have impact on the access efficiency for composite M-services. A multiprocess workflow is proposed for effectively accessing composite M-services from multiple broadcast channels based on these semantics. We also present and compare different broadcast channel organizations for M-services and wireless data. Analytical models are provided for these channel organizations. Practical studies are presented to demonstrate the impact of different semantics and channel organizations on the access efficiency.     

Query optimization for broadcast database

In a mobile environment, the broadcast paradigm has been recognized as an effective way to disseminate frequently requested information to multiple ‘mobile clients’. In this paper, we show that to query the broadcast database efficiently, database items must be organized over the broadcast channel in a meaningful way, reflecting the semantics of the database being broadcast. We define, for the first time, a cost model called the Semantic Ordering Model for identifying the optimal organization of database items over the broadcast channel. Experimental results are also delineated to illustrate the feasibility of our cost model, using relational and object-oriented databases as examples.     

Object Organization on a Single Broadcast Channel in the Mobile Computing Environment

Advances in computation and communication technologies allow users to access computer networks, using portable computing devices via a wireless connection, while mobile. Furthermore, multidatabases offer practical means of managing information sharing from multiple preexisting heterogeneous databases. By superimposing the mobile computing environment onto the multidatabase system, a new computing environment is attained.In this work, we concentrate on the effects of the mobile-computing environment on query processing in multidatabases. We show how broadcasting, as a possible solution, would respond to current challenges such as bandwidth and storage limitations. Organizing data objects along a single-dimension broadcast channel should follow the semantic links assumed within the multiple-dimension objects' structure. Learning from our past experiences in objects organization on conventional storage mediums (disks), we propose schemes for organizing objects along a single broadcast air channel. The proposed schemes are simulated and analyzed.     

一种最小连通支配集的分布式广播算法

研究移动自组网络中的广播算法,提出了一种适用于移动自组网络的基于最小连通支配集的分布式广播算法,并证明了新的广播算法与已有算法相比能够更加有效地解决网络采用洪泛(Flooding)方式进行广播时所可能产生的广播风暴问题。同时,算法是基于并行和分布式运行模式的,因此具有很好的扩展性和实用性。     

Optimal transmission schemes for parallel and fading Gaussian broadcast channels with an energy harvesting rechargeable transmitter

We consider an energy harvesting transmitter sending messages to two users over parallel and fading Gaussian broadcast channels. Energy required for communication arrives (is harvested) at the transmitter and a finite-capacity battery stores it before being consumed for transmission. Under off-line knowledge of energy arrival and channel fading variations, we obtain the trade-off between the performances of the users by characterizing the maximum departure region in a given interval. We first analyze the transmission with an energy harvesting transmitter over parallel broadcast channels. We show that the optimal total transmit power policy that achieves the boundary of the maximum departure region is the same as the optimal policy for the non-fading broadcast channel, which does not depend on the priorities of the users, and therefore is the same as the optimal policy for the non-fading scalar single-user channel. The optimal total transmit power can be found by a directional water-filling algorithm. The optimal splitting of the power among the parallel channels is performed in each epoch separately. Next, we consider fading broadcast channels and obtain the transmission policies that achieve the boundary of the maximum departure region. The optimal total transmit power allocation policy is found using a specific directional water-filling algorithm for fading broadcast channels. The optimal power allocation depends on the priorities of the users unlike in the case of parallel broadcast channels. Finally, we provide numerical illustrations of the optimal policies and maximum departure regions for both parallel and fading broadcast channels.