The impact of interference-aware routing metrics on video streaming in Wireless Mesh Networks

Wireless Mesh Networks form a wireless backbone that provides ubiquitous Internet access and support of multimedia services. In this scenario, traffic crosses multi-hop paths, through mesh routers and gateways, causing high levels of interference. To address this problem, the use of schemes that introduce routing metrics that take into account the characteristics of the interference have been made to improve the application performance. Given the diversity of interference-aware routing metrics for Wireless Mesh Networks, it is necessary to assess the impact of employing these routing metrics on multimedia traffic performance, and in particular, on video streaming. This paper seeks to fill this gap, by using simulation to evaluate the video streaming performance when the most relevant interference-aware routing metrics are used. The degree of video quality can be evaluated from two perspectives, the network viewpoint and the standpoint of the user perception. At the network level, video streaming quality is assessed through IP measures, that is, throughput, delay, jitter and routing overhead. At the user level, ‘Quality of Experience’ metrics are employed to measure the user perception with regard to the video quality. The evaluation of the performance takes account of outdoor and indoor environments. The results of the simulation study have shown that routing metrics based on the information that detects interference using accurate measures achieve a better network and user perception performance. However, depending on the environment (i.e., whether it is indoor or outdoor), all the routing metrics result in a different performance being achieved. Although interference-aware routing metrics affect the performance of both the network and the user levels, there are some cases where they have less impact on the user level, because the user perception parameters are less influenced by the behaviour of the network.     

Wireless identification — privacy and security

The government has plans for electronic ID cards, passports and vehicle identification. In industry, smartcards, intelligent tickets, RFID and active tags are increasingly available at low cost. Technology that was not originally designed for identification and tracking is now being used in that role. Wi-Fi tags are now available, and a number of technology vendors provide Wi-Fi location-based services. We are seeing a proliferation of user and object identifiers (more correctly termed ‘identifying tokens’) that can be read at a range. Barriers between the physical and information world are disappearing and contactless identifiers promise great benefits for their users. Identifiers can be read at high speeds and low cost without human intervention. The convergence of technologies causes an increased number of players to rely on identifiers that are reused in multiple domains and contexts. The result is that the user loses control over their identifiers, and security and privacy vulnerabilities affect the value of the identifiers to applications. In this paper, we describe what we mean by identifier security, and discuss the options available to the system designer to mitigate the security and privacy risks. We remark on the lack of a common regulatory framework for the control of identifiers, and suggest that technology should be used to provide the first and best layer of defence.     

An Improved E-Payment System and Its Extension to a Payment System for Visually Impaired and Blind People with User Anonymity

Electronic payment systems have become increasingly popular due to the widespread use of the internet-based shopping and banking. Such systems should at least guarantee users’ anonymity during the transaction, fair exchange of goods and offer dispute resolutions. As many of the electronic payments are nowadays performed on mobile devices, also efficiency with respect to communication and computation costs at the user’s side is another important requirement. In this paper we first show that a previously proposed system does not offer the claimed anonymity and non repudiation features. These issues are based on problems in the underlying authenticated encryption scheme. We propose an alternative system that satisfies all the required security features. In addition, we show how similar techniques can be applied to develop a payment system on a vending machine or in a retail outlet for the user using its smartphone as proxy, allowing besides confidentiality and authentication, also user anonymity throughout the whole process. This payment system is in particular of interest for blind or visually impaired people, who become able to take the whole payment process in own hands, instead of being dependent of the payment device and the possibly untrusted environment. Both payment systems apply the anonymous signcryption scheme ASEC as building block.

     

Base station placement for in-building mobile communication systemsto yield high capacity and efficiency

A study is made of the problem of placing base stations to yield high capacity and efficiency in an in-building direct-sequence code-division multiple-access wireless communication system. A key requirement for solving this problem is a reliable but simple model of in-building propagation. A number of propagation models are considered as part of a system's performance analysis and are found to produce widely ranging levels of accuracy. Correlated shadowing is identified as being a `key'in-building propagation characteristic that has the potential to strongly influence the system's performance. Propagation models that included correlated shadowing are shown to produce the most accurate estimates of outage probability when there are a number of interferers facing a user. Base station deployment is shown to be a dominant factor influencing the levels of correlated shadowing, and consequently, base station deployment is shown to have major implications on the system's performance. The system's performance for a variety of base station deployment strategies has been determined. The results indicate that there is a tradeoff between system simplicity and performance     

A Privacy Preserving Method Using Privacy Enhancing Techniques for Location Based Services

The move towards service-oriented architectures and the increasing usage of mobile devices to access such services are two of the major changes in modern computing. Information about the user, their location and their trajectory can provide additional context information to a service, leading to useful applications such as directing a user to the nearest bus stop and displaying which buses are due to arrive in the next minutes. While this type of information can be useful, when the offered services are trusted, it also introduces privacy issues relating to gathering of location information for non-trusted applications like location-based marketing or user behaviour profiling. Users can limit their location information provided to a service but these controls are simple, making it important for the user to understand how their location information is being used by services. This paper reviews some of the methods currently being proposed to reduce the impact of location tracking on user privacy, and presents a novel encryption method for preserving the location and trajectory path of a user using Privacy-Enhancing Technologies.     

Plastic encapsulated microcircuit reliability predicition: why?

Reliability prediction models for microcircuits have been a function of steady-state temperature. Failure rates generated from accelerated temperature tests were extrapolated to predict system reliability at system use temperatures. This is now known to be completely inaccurate. Attempts are now being made to predict the reliability of plastic encapsulated microcircuits (PEMs) based on accelerated temperature/humidity testing. Failure rates generated due to corrosion failure mechanisms at these high stress levels are then extrapolated and used to predict system reliability at used temperature/humidity conditions.This paper discusses the fallacy of this approach. A new concept for the assurance of PEM corrosion resistance is proposed. It will be shown that today's best commercial practice suppliers have already addressed the design, materials, and processing issues of molded packaged microcircuits, and corrosion is no longer a mechanism of concern to the user.     

PSIM-based modeling of automotive power systems: conventional, electric, and hybrid electric vehicles

Automotive manufacturers have been taking advantage of simulation tools for modeling and analyzing various types of vehicles, such as conventional, electric, and hybrid electric vehicles. These simulation tools are of great assistance to engineers and researchers to reduce product-development cycle time, improve the quality of the design, and simplify the analysis without costly and time-consuming experiments. In this paper, a modeling tool that has been developed to study automotive systems using the power electronics simulator (PSIM) software is presented. PSIM was originally made for simulating power electronic converters and motor drives. This user-friendly simulation package is able to simulate electric/electronic circuits; however, it has no capability for simulating the entire system of an automobile. This paper discusses the PSIM validity as an automotive simulation tool by creating module boxes for not only the electrical systems, but also the mechanical, energy-storage, and thermal systems of the vehicles. These modules include internal combustion engines, fuel converters, transmissions, torque couplers, and batteries. Once these modules are made and stored in the library, the user can make the car model either a conventional, an electric, or a hybrid vehicle at will, just by dragging and dropping onto a schematic blank page.     

A Low Computational-Cost Electronic Payment Scheme for Mobile Commerce with Large-Scale Mobile Users

The electronic transactions on wireless mobile networks, which are also called mobile commerce, become more and more popular in recent years. In mobile commerce, the electronic payment is the most important component and thus many electronic payment schemes for mobile commerce are proposed. However, these schemes need to maintain a large authentication table for a large amount of mobile users. In addition, these schemes have heavy computation loads so they are not suitable for low computational-ability mobile devices. To overcome the above drawbacks, we propose a low computation-cost electronic payment scheme for mobile commerce in this paper. The proposed scheme can be applied to large-scale mobile user environments without maintaining a large authentication table. Moreover, the proposed scheme has low computation loads for mobile users because the elliptic curve cryptography is adopted in the proposed scheme. Therefore, the proposed scheme is more efficient and practical than the related works.     

基于机器学习的用户实体行为分析技术在账号异常检测中的应用

伴随企业业务的不断扩增和电子化发展,企业自身数据和负载数据都开始暴增。然而,作为企业核心资产之一的内部数据,却面临着日益严峻的安全威胁。越来越多以周期长、频率低、隐蔽强为典型特征的非明显攻击绕过传统安全检测方法,对大量数据造成损毁。当前,用户实体行为分析(User and Entity Behavior Analytics,UEBA)系统正作为一种新兴的异常用户检测体系在逐步颠覆传统防御手段,开启网络安全保卫从“被动防御”到“主动出击”的新篇章。因此,将主要介绍UEBA在企业异常用户检测中的应用情况。首先,通过用户、实体、行为三要素的关联,整合可以反映用户行为基线的各类数据;其次,定义4类特征提取维度,有效提取几十种最能反映用户异常的基础特征;再次,将3种异常检测算法通过集成学习方法用于异常用户建模;最后,通过异常打分,定位异常风险最大的一批用户。在实践中,对排名前10的异常用户进行排查,证明安恒信息的UEBA落地方式在异常用户检测中极其高效。     

基于用户令牌的数字签名在电子政务建设中的应用

数字签名在电子政务安全建设中非常重要,文章描述了几类数字签名体制,提出基于用户令牌的数字签名在电子政务中的应用设计方案,并对其进行了分析。     

Performance of Punctured Convolutional Codes in A-CDMA Systems with Accurately Modelled Multiple Access Interference Under Perfect Phase Tracking Conditions

In this paper, a simplified expression for Improved Gaussian Approximation is considered to model multiple access interference in an A-CDMA system. Punctured convolutional codes, which are one of the subclasses of convolutional codes, are employed to provide error protection to the information transmitted over the wireless channel. A detailed theoretical analysis is made initially and then compared with the simulated results for various code rates. The simulated performance of the codes is then compared for different power levels and different number of interferers of the desired user. A perfect phase reference is assumed to be available for the information signal of the desired user throughout this paper.     

On-Line E-Wallet System with Decentralized Credential Keepers

We propose a generalization of the architecture of an electronic wallet, as first developed in the seminal European research project CAFE. With this model you can leave most of the content of your electronic wallet at the security of your residential electronic keeper, while roaming with your favorite mobile terminals. Emerging mobile handsets with both short range Bluetooth and cellular GPRS communications provide a sufficient communication platform for this electronic wallet architecture. However, new security requirements must be addressed, and new threats of attack must be carefully analyzed and met with appropriate security protocols. The proposed approach is fundamentally distinct from the remote wallet proposals, in that it protects important user requirements and takes a multiparty security approach using a fully decentralized architecture. Technically, the user remains in control of the input/output and usage of his credentials, likely carried by smart cards. At the same time, the model provides a solution to the pressing practical problem of the multitude of special-branded cards the user has to carry and sort. Currently used magnetic stripe and chip cards with applications such as debit and credit transactions are easily included within the architecture with minor enhancement to these legacy systems and their functionality. We show in this paper how an account-based payment system can be solved with the proposed architecture. Our claim is that users achieve payment mobility and independence of both terminals and payment service providers while maintaining secure access to their payment authorization credentials.     

Current‐Induced Restructuring and Chemical Modification of N‐Doped Multi‐walled Carbon Nanotubes

Multi‐walled carbon nanotubes (MWCNTs) have long been anticipated as candidates for electrical components in an increasingly miniaturized electronics industry due to their inherent electrical properties. It is possible to manipulate and control these properties by introducing dopants such as N, B, and P. Although some current‐induced structural changes in MWCNTs have been observed, no systematic study has been carried out to explore the correlation of changes in the internal structure with the electronic behavior of doped‐MWCNTs in terms of the current densities present. In situ transmission electron microscopy (TEM) investigations are presented here of individual, N‐doped MWNCT (N‐MWCNTs) using the in situ TEM/scanning tunneling microscopy (TEM/STM) Nanofactory© holder. It is observed for the first time that N‐MWCNTs not only undergo current‐induced structural transformation; i.e., from the typical bamboo structure of N‐MWCNTs to the stacked cones, but also—and most importantly—the complete removal of the dopant causes a significant change in the electronic behavior. This has serious implications for the use of doped CNTs as electronic components, especially since tremendous efforts are being made to synthesize CNTs with controlled dopant concentrations.     

Adhesion evaluation on low-cost alternatives to thermosetting epoxy encapsulants

The thermosetting epoxy curing systems have been widely used as encapsulants in the electronic packaging industry. With the continual evolving of electronic product markets, material suppliers have been challenged to provide more options to meet the requirements of advanced, yet cost effective, packaging solutions. In this paper, two low-cost alternative materials have been investigated experimentally regarding their adhesion and reliability performance, and these have then been compared with the thermosetting epoxy systems. One of the materials is thermoplastic bisphenol A epoxy/phenoxy resin, and the other is an interpenetrating polymer network composed of an epoxy curing component and a free radical polymerizable component. Some formulations of the materials being studied could exhibit excellent adhesion, durability and application reliability. While reworkability is expected for these materials, they are promising as cost effective encapsulants for electronic packaging, and may be applied with appropriate processing techniques.     

认知电子战发展趋势:从单体智能到群体智能

随着人工智能、通信技术、无人系统等技术的快速发展,通信对抗装备智能水平不断提高,无人集群作战也在持续地深化和落地应用,这给认知电子战技术的研究带来了新的机遇和挑战,推动了认知电子战内涵从单体化向群体化演进。为促进认知电子战发展有效适应未来新型智能作战装备和新型无人集群作战样式,在综述认知电子战概念、内涵以及认知电子战单体智能研究的基础上,从无人集群作战背景出发,结合群体智能算法,提出了认知电子战群体智能的概念并对其内涵进行详细的阐述,指明了其对认知电子战的研究价值、应用价值以及发展前景。最后,在体系对抗的视角下,进一步对认知电子战群体智能未来可能的发展方向进行了较为全面的展望。     

Comparison of GaAs device approaches for ultrahigh-speed VLSI

The superior electronic properties of gallium arsenide and related III-V compound semiconductors, as compared with silicon, have made them of great interest for ultrahigh-speed logic applications. Many ingenious device structures have been proposed or demonstrated for utilizing the advantageous electron dynamics of GsAs to achieve ultralow propagation delay and/or ultralow power-delay product (dynamic switching energy) logic circuits. The intent of this paper is to give an overview of some of these GaAs device approaches, including their principal, attractions, expected performance levels, etc. (Much more detailed analyses of some of these structures are presented in other papers in this issue.) This overview is extended to a comparison of the relative merits of these GaAs device approaches vis-à-vis their applicability for achieving ultra high-speed logic of large-scale integration (LSI) or very large-scale integration (VLSI) levels of complexity (as opposed to simpler SSI/MSI applications).     

A contextual role-based access control authorization model for electronic patient record

The design of proper models for authorization and access control for electronic patient record (EPR) is essential to a wide scale use of EPR in large health organizations. In this paper, we propose a contextual role-based access control authorization model aiming to increase the patient privacy and the confidentiality of patient data, whereas being flexible enough to consider specific cases. This model regulates user's access to EPR based on organizational roles. It supports a role-tree hierarchy with authorization inheritance; positive and negative authorizations; static and dynamic separation of duties based on weak and strong role conflicts. Contextual authorizations use environmental information available at access time, like user/patient relationship, in order to decide whether a user is allowed to access an EPR resource. This enables the specification of a more flexible and precise authorization policy, where permission is granted or denied according to the right and the need of the user to carry out a particular job function.     

Automatic Learning of User Profiles — Towards the Personalisation of Agent Services

Agent technology is able to provide increasingly more services for individuals, groups and organisations. Services such as information finding, filtering and presentation, service/contract negotiation, and electronic commerce are now possible. User profiling is fundamental to the personalisation of this technology. This paper describes experimental work conducted to investigate user profiling within a framework for personal agents. In particular investigations were aimed at discovering whether user interests could be automatically classified through the use of several heuristics. The results highlighted the need for minimal user feedback, and the need to consider the implications for the role of machine learning in user profiling.