适应自组织管理模式的P2P资源共享网络激励模型的研究

P2P网络中的自组织管理模式使得节点的自私行为大量存在.建立相应解决方案所面临的主要问题是难以继续维持P2P网络拥有的自组织及规模可扩放性等特性.目前存在的信用管理模型或者激励模型多是采用泛洪方式获得网络其他节点的历史行为信息,庞大的报文通信量和推导算法的高时间复杂度制约了所能应用的P2P网络的规模.本文提出了一种利用随机相遇博弈理论指导建立的P2P资源共享网络激励模型ResP2P.该模型通过引入节点信誉及信誉恢复区分机制,同时制定相关行为社会规范,来激励理性节点为使其自身收益最大化而向整个网络贡献资源,并且ResP2P所对应的分布式算法易于在自组织管理模式的网络环境中实施.实验证实了ResP2P模型激励机制的有效性.     

A Generic Quantitative Approach to the Scheduling of Synchronous Packets in a Shared Uplink Wireless Channel

The scheduling logic at the base station of a shared wireless medium supports time-dependent (synchronous) applications by allocating timely transmission grants. To this end, it must take into account not only the deadlines of the pending packets, but also the channel conditions for each potential sender, the requirements of nonsynchronous applications, and the packet retransmission strategy. With respect to these factors, we identify three scheduling scenarios and show that the scheduler logic faces a different challenge in addressing each of them. We then present a generic scheduling algorithm that translates all the factors relevant to each scenario into a common profit parameter, and selects the most profitable transmission instances.     

A Novel Charge Transfer Channel to Simultaneously Enhance Photocatalytic Water Splitting Activity and Stability of CdS

It is highly desirable to develop durable photocatalysts for efficiently boosting water splitting, but it is challenging for CdS to realize the expected result without using any hole sacrificial agents. Herein, improved photocatalytic hydrogen evolution and enhanced stability are simultaneously realized in the absence of any sacrificial agents by introducing Zinc 5‐, 10‐, 15‐, 20‐meso‐tetra (4‐hydrazidephenyl) porphyrin (ZnTHPP) onto CdS nanosheets (CdS NSs). In this system (ZnTHPP/CdS NSs), a novel hole transfer channel is achieved by an internal chemical reaction using the functional group of acylhydrazine in ZnTHPP. Compared with CdS NSs, the ZnTHPP/CdS NSs exhibit excellent photostability (15 h) and efficient photocatalytic activity for pure water splitting (≈6.4 times). Furthermore, it is found that the rate constant for photogenerated holes is about 1.7 times higher than the pure CdS NSs under light irradiation. This suggests that the promising charge transfer channel can efficiently suppress charge recombination and photocorrosion of pure CdS NSs. The pattern via internal charge transfer channel not only can solve the stability of CdS based materials, but also design more semiconductors for efficient photocatalytic water splitting.     

Increasing Lifetime and Fault Tolerance Capability in Wireless Sensor Networks by Providing a Novel Management Framework

The main application of wireless sensor networks is to monitor remote and dangerous areas that are inaccessible or difficult and or costly to reach by humans. This characteristic makes these networks be self-managed, face the challenges of fault tolerance and energy and network lifetime constraints due to non-renewable energy sources. In this paper, a management framework capable of providing and increasing network fault tolerance is introduced. To design such a framework, fault detection and recovery mechanisms for various fault levels including network nodes and communications between them have been used. The proposed management framework and protocols increase network’s fault tolerance capability in network nodes and in the communications between them. Also, the network lifetime increases three to five times more. On the one hand, it’s expected that the provision of network fault tolerance would decrease network’s lifetime and since it increases information exchange, it would increase energy consumption and cause reduced network life time, however the final results suggest a several-fold increase of network lifetime.     

Fault Tolerance and Energy Efficient Clustering Algorithm in Wireless Sensor Networks: FTEC

Wireless Personal Communications - The beacon order and Superframe order parameter values, as defined by the IEEE 802.15.4 standard specification, constrain the number of data packets that can be...     

一个基于网格资源超市的计算网格资源管理模型

在现有的基于经济模型的网格资源管理方法中,用户共享资源访问一般经由网格用户代理实现,而资源提供者将资源交给网格资源代理处理,网格用户代理通过网格资源经纪访问网格资源代理,获取共享资源信息并使用共享资源。这类方法制约了用户直接选择使用共享资源,也限制了用户共享资源的范围、延长了作业运行周期。文章给出的基于网格资源超市的计算网格资源管理模型、共享资源访问流程及网格资源管理分配策略,较好地解决了这几个问题。     

Resource Allocation for Real Time Services in LTE Networks: Resource Allocation Using Cooperative Game Theory and Virtual Token Mechanism

The LTE specifications provide QoS for multimedia services with fast connectivity, high mobility and security. However, 3GPP specifications have not defined scheduling algorithms to exploit the LTE characteristics to support real time services. In this article we propose a two level scheduling scheme composed by cooperative game theory, a virtual token mechanism, and the well known algorithms EXP-RULE and Modified-Largest Weighted Delay Firs (M-LWDF) in downlink system. By using cooperative game theory such as bankruptcy game and Shapley value, the proposed mechanism works by forming coalitions between flow classes to distribute the bandwidth fairly among all of them. Both algorithms EXP-RULE and M-LWDF have been modified to use a virtual token mechanism to improve their performance, giving priority to real time flows. By taking the arrival rate of packets into account, the proposed mechanism partially included in previous schedulers has been adapted to this work to increase remarkably the performance of the resource allocation for real time flows. The performance evaluation is conducted in terms of system throughput, Packet loss ratio, total cell spectral efficiency, delay and fairness index.     

Radio Resource Management in MIMO-OFDM- Mesh Networks: Issues and Approaches

We present a survey on the radio resource management issues in MIMO-OFDM-based infrastructure wireless mesh networks. The major components in radio resource management (i.e., scheduling and admission control) and related research issues are discussed. We review related work in the literature. We propose a game-theoretic model for admission control in IEEE 802.11n-based WMNs using the MIMO-OFDM technology. The proposed scheme uses Q-learning, which is a reinforcement learning algorithm, to gain knowledge on system performance. Then this knowledge is used to determine payoff for the game formulation to obtain the Nash equilibrium for the decision on admitting or rejecting a new connection at a mesh router.     

Automatic Uplink Resource Management in Mobile Cellular Networks: A Utility-Based Cooperative Power Control Strategy

This paper proposes a cooperative power control strategy for resource adaptation in mobile network to optimize user uplink transmission power. Our approach is based on a cooperative model using the economic concepts of utility function and the random graph theory. Based on the model, we develop a distributed power control algorithm that maximizes the utilities of all mobile users. Formulating this algorithm as a cooperative strategy, we show the uncertainty and existence of the power control approach with theory of random bipartite graph and utility function. A discussion to the existence of optimal solutions is given. Then a distributed power control scheme is proposed based on the optimal solutions. It is shown by way of simulation that by introducing utility function in the power control algorithm, there is a performance improvement in terms of the utilities that mobile users obtained. Numerical results are presented for the algorithm.     

Small Cell Planning: Resource Management and Interference Mitigation Mechanisms in LTE HetNets

In an attempt to address the huge data demand of indoor mobile users and poor signal strength from outdoor base stations to indoor environments, opertaors have started deploying variety of small cells likes Femtos, picos and micro cells. In this work, we used Femtos as small cells. Femto cells are low-cost, low-power consuming cellular base stations which operate only in licensed spectrum and are designed for both outdoor and indoor communication. Although small cells can be used for enhancing network capacity and coverage, arbitrary deployment of large number of small cells can lead to increase in operators expenditure and may create severe interference issues for cell edge users. In this paper, we look into optimal placement of small cell solutions to improve data rates of users in LTE HetNets using Femtos. Besides, these solutions address the main concerns of interference and resource management by proposing mechanisms for optimal placement of Femtos (OptFP, MinNF), dynamic power control and bandwidth allocation in Femtos (SOPC) and dynamic offloading. We provide a comparison of placement solutions and the applicability of each proposal keeping the operators’ revenue in mind.

     

LPR: A CT and MR-Compatible Puncture Robot to Enhance Accuracy and Safety of Image-Guided Interventions

Image-guided percutaneous interventions are common procedures used for diagnosis or therapeutic purposes. The clinical demand for such interventions is growing since they are minimally invasive. To increase the quality of the operations and provide optimal accuracy and safety to patients, puncture robots may be very helpful. This paper presents a new robotic architecture designed to perform abdominal and thoracic punctures under computer tomography (CT) or MRI guidance. Innovations concerning the robotic architecture, materials, and energy sources are described. Segmentation and registration algorithms have been developed to localize the robot on images coming from CT or MRI devices, and a specific control loop is used to verify the movements and the positioning of the robot. The results of the initial experiments made under CT and MRI environments are presented.     

P2P下基于RSA密码机制和门限秘密共享的信誉管理方案

在P2P网络环境下,利用RSA密码机制和门限秘密共享进行信誉管理是一个非常有效的方案。利用秘密共享原理将信誉信息分成n个秘密份额,其中的任意t （t＜n ）个合法的秘密共享参与者均可以重新构造信誉信息。为了有效地防止网络中的恶意实体进行欺诈,方案中还配备了与每个秘密份额相对应的验证份额分发给相应的参与实体,任何非法参与实体冒称拥有秘密份额或者参与实体提供虚假的秘密份额,只有攻破了RSA密码才能不被识别出来,因此方案是安全有效的。     

Correction to: G2A Communication Channel Modeling and Characterization Using Confocal Prolates

Wireless Personal Communications - The original publication contains the following errors:     

A Real-Time Monitoring and Intelligent Decisions-Making Platform for Enhanced Radio Resource Management in Wireless Cellular Systems

Congestion management in cellular networks is of prime importance for the mobile network operators of present and future generations. Nowadays cellular operators utilize improved planning techniques for enhanced capacity management, but on the other hand the number of mobile subscribers rapidly increases and additionally, new data-technologies for wireless access add extra traffic to the already overloaded networks, often causing serious problems to their performance. In this paper, we present a resource management system for increasing the efficiency of 2G and 2.5G cellular networks especially during overloading periods through the introduction of innovative extra elements. For validating the system's behavior, a set of trials have been performed focusing on alleviating both voice and data congestion problems. The results of these trials show important improvements on the network's capacity availability when the presented system intervenes.     

Variable Frame Rate Transmission: A Review of Methodology and Application to Narrow-Band LPC Speech Coding

We review the variable frame rate (VFR) transmission methodology that we developed, implemented, and tested during the period 1973-1978 for efficiently transmitting LPC vocoder parameters extracted from the input speech at a fixed frame rate. In the VFR method, parameters are transmitted only when their values have changed sufficiently over the interval since their preceding transmission. We explored two distinct approaches to automatic implementation of the VFR method. The first approach bases the transmission decisions on comparisons of the parameter values of the present frame and the last transmitted frame. The second approach, which is based on a functional perceptual model of speech, compares the parameter values of all the frames that lie in the interval between the present frame and the last transmitted frame against a linear model of parameter variation over that interval. The application of VFR transmission to the design of narrow-band LPC speech coders with average bit rates of 2000-2400 bits/s is also considered. The transmission decisions are made separately for the three sets of LPC parameters, pitch, gain, and spectral parameters, using separate VFR schemes. A formal subjective spccch quality test of six selected LPC coders is described, and the results are presented and analyzed in detail. It is shown that a 2075 bit/s VFR coder produces speech quality equal to or better than that of a 5700 bit/s fixed frame rate coder.     

Correction to: Power and Resource Allocation in Wireless Communication Network

Wireless Personal Communications - Relying on the fact that, cascaded $$\alpha$$ – $$\mu$$ distribution provide simplified and excellent fitting to the measurement data compared to the other...     

Developments in the SL-10 Packet Switch: Resource, File, and Software Loading Management

The Northern Telecom SL-10 Packet Switching System is steadily enhanced to provide better access services for users. Equally important to them, but less visible, are enhancements to improve availability and increase throughput. To this end, intelligent peripheral devices, such as storage controllers and line servers, have been added to the Switch and new strategies, especially for software loading, have been devised. Such additions have had an impact on the software architecture. The Resource Subsystem now has to cope with a wider variety of devices, including intelligent peripheral devices. The File Subsystem has been generalized to accommodate files on different types of volumes, e.g., disks and tape cartridges. A whole new Subsystem has evolved to handle strategies for loading processors in parallel and to load intelligent peripherals. The SL-10 Packet Switch software architecture, with its process environment structured in Subsystems, has proven well suited to these requirements.     

反应离子深刻蚀中加强热传递和抑制Notching效应的方法

提出了一种在反应离子深刻蚀中既可以加强热传递又可以抑制notching效应的方法,尤其适用于含有细长梁结构的刻蚀.通过在硅结构的下表面溅射一薄层金属,以加强刻蚀过程中产生的热量的消散,降低了硅结构的温度.用有限元仿真和实验分别验证了该方法的有效性.同时,金属层也抑制了刻蚀离子所带电荷在绝缘介质层上的积累,防止了自建电场的产生,抑制了notching效应.该方法通过扫描电子显微镜的测量也得到了实验验证.加工了一个SOI梳齿驱动器,检验了本方法的有效性和适应性.     

一种虚拟机系统下关于多级安全的强制访问控制框架II:实现

This paper is a continuation of our last paper [1] which describes the theory of Virt-BLP model. Based on Virt-BLP model, this paper implements a mandatory access control (MAC) framework applicable to multi-level security (MLS) in Xen. The Virt-BLP model is the theoretical basis of this MAC framework, and this MAC framework is the implementation of Virt-BLP model. Our last paper focuses on Virt-BLP model, while this paper concentrates on the design and implementation of MAC framework. For there is no MAC framework applicable to MLS in virtual machine system at present, our MAC framework fills the blank by applying Virt-BLP model to Xen, which is better than current researches to guarantee the security of communication between virtual machines (VMs). The experimental results show that our MAC framework is effective to manage the communication between VMs.