ACDAS: Authenticated controlled data access and sharing scheme for cloud storage

Cloud storage services require cost‐effective, scalable, and self‐managed secure data management functionality. Public cloud storage always enforces users to adopt the restricted generic security consideration provided by the cloud service provider. On the contrary, private cloud storage gives users the opportunity to configure a self‐managed and controlled authenticated data security model to control the accessing and sharing of data in a private cloud. However, this introduces several new challenges to data security. One critical issue is how to enable a secure, authenticated data storage model for data access with controlled data accessibility. In this paper, we propose an authenticated controlled data access and sharing scheme called ACDAS to address this issue. In our proposed scheme, we employ a biometric‐based authentication model for secure access to data storage and sharing. To provide flexible data sharing under the control of a data owner, we propose a variant of a proxy reencryption scheme where the cloud server uses a proxy reencryption key and the data owner generates a credential token during decryption to control the accessibility of the users. The security analysis shows that our proposed scheme is resistant to various attacks, including a stolen verifier attack, a replay attack, a password guessing attack, and a stolen mobile device attack. Further, our proposed scheme satisfies the considered security requirements of a data storage and sharing system. The experimental results demonstrate that ACDAS can achieve the security goals together with the practical efficiency of storage, computation, and communication compared with other related schemes.     

Transmission control protocol performance enhancement for mobile broadband interactive satellite communication system: a cross‐layer approach

Mobile broadband interactive satellite communication system is of great interest in both academic and industrial communities. However, the conventional strict‐layered protocol stack architecture and the standard TCP version perform poorly over satellite link. In this paper, we propose a comprehensive cross‐layer Transmission Control Protocol (TCP) optimization architecture while considering the main factors that affect the TCP performance. In our proposed architecture, we adopt two TCP split connection performance enhancing proxies to isolate the satellite link from the terrestrial part of the broadband satellite communication system. Then, based on the proposed cross‐layer architecture, we present an analytical model for the TCP throughput by taking the modulation and coding (ModCod) mode and the allocated bandwidth into account. In addition, we put forward a TCP‐driven bandwidth sharing and ModCod mode optimization algorithm to maximize the TCP throughput in satellite link. Extensive simulation results illustrate that our proposed comprehensive cross‐layer TCP optimization approach is able to improve the TCP throughput significantly. Copyright © 2014 John Wiley & Sons, Ltd.     

Performance analysis of integrating voice and data services over PACS systems in a multicarrier environment

The purpose of this paper is to study the performance of integrating voice and data services over PACS systems in a multicarrier environment. Several time‐slot allocation schemes are proposed. With continuous‐time Markov model, the performance can be evaluated. The results show that while using one system broadcast channel (SBC), the blocking rate of circuit mode services and system throughput are improved, at the sacrifice of increasing the blocking probability of packet mode services. Copyright © 2002 John Wiley & Sons, Ltd.     

Smart grid sensor data collection,communication, and networking: a tutorial

The smart grid is an innovative energy network that will improve the conventional electrical grid network to be more reliable, cooperative, responsive, and economical. Within the context of the new capabilities, advanced data sensing, communication, and networking technology will play a significant role in shaping the future of the smart grid. The smart grid will require a flexible and efficient framework to ensure the collection of timely and accurate information from various locations in power grid to provide continuous and reliable operation. This article presents a tutorial on the sensor data collection, communications, and networking issues for the smart grid. First, the applications of data sensing in the smart grid are reviewed. Then, the requirements for data sensing and collection, the corresponding sensors and actuators, and the communication and networking architecture are discussed. The communication technologies and the data communication network architecture and protocols for the smart grid are described. Next, different emerging techniques for data sensing, communications, and sensor data networking are reviewed. The issues related to security of data sensing and communications in the smart grid are then discussed. To this end, the standardization activities and use cases related to data sensing and communications in the smart grid are summarized. Finally, several open issues and challenges are outlined. Copyright © 2012 John Wiley & Sons, Ltd.     

RS码类的构建及在数据链模拟系统中的应用

Reed-Solomon码(RS码)具有强大的纠错能力,在数据通信中得到了广泛的应用,如RS(31,15)码已经成为美军数据链系统的标准码。为了实现应用于数据链模拟系统中的RS编译码类,从分析RS纠错编译码原理入手,在研究了RS编译码模型的基础上,重点对RS编译码的编程实现方法进行了详细分析。以VC++为编程实现平台,采用面向对象的程序设计方法,构建且封装了RS编译码类,最后对RS编译码类的纠错性能进行了验证,结果表明,设计的RS编译码类能够有效纠错且正确恢复发端发送的信息,满足模拟系统的设计要求。     

物联网搜索中主客观融合的动态信誉评估

与传统的互联网搜索相比,物联网搜索更加强调数据质量。为了提高数据质量,物联网搜索中心需要依数据质量为提供者支付相应报酬以激励其持续提供符合质量需求的数据。这就使如何评估数据提供者的数据质量及其信誉成为物联网搜索中的一个基础问题。为此,引入动态信誉机制来综合评估数据提供者的可信性,为数据选择、收集提供依据。首先,提出了主观意愿及客观质量评价计算方法,并设计了交互行为贴现及信誉衰减机制;然后,提出了融合主客观要素的动态信誉计算模型,并基于信号传递机制进行博弈分析,以获取交互次数、贴现率、支付价格及数据成本之间约束关系。实验证明该模型能够较好地反映数据质量变化情况,为数据选择提供依据,并满足物联网搜索的实时性及动态性需求。     

Electrical and optical clock and data recovery in optical access networks: a comparative study

Clock and data recovery (CDR) is an essential part in high‐speed telecommunication systems. The CDR is used to extract the clock and re‐time the received data, which allows a synchronous operation to recover the transmitted signal. In optical access networks, electrical CDR or optical CDR implementations can be used. However, there are no clear guidelines or recommendations on which CDR implementation should be adopted for better performance. These missing clear recommendations are because the electrical CDR requires electronics design expertise whereas the optical CDR requires optical design expertise. Consequently, in this paper, an all‐digital CDR, designed and implemented on the field‐programmable gate array platform, and an optical CDR, developed by using fiber Bragg grating technology on the OptiSystem platform, are presented. Furthermore, the integration of these 2 CDR implementations with the optical access network is implemented, and their performance is evaluated for various transmission rates and communication distances. Finally, a comparative study in terms of the bit error rate between the all‐digital CDR and the optical CDR is presented.     

从《欧美隐私盾》协议失效看美国政府电子数据调取体系

从《欧美隐私盾》协议被欧盟法院判定无效的核心论据出发,对美国政府基于不同执法目的下的电子数据调取体系进行了探究。指出尽管美国政府在一般执法情形下的数据调取体系较为严谨和规范,但是基于国家安全目的的数据监视和调取体系具有一定的不透明性和不规范性,正是这一特点导致欧盟法院认为其无法满足欧盟对于个人数据的保护标准,从而给两者的数据跨境传输合作机制带来了负面影响。     

Expectation–maximization‐based joint data detection and channel estimation for a cellular multi‐carrier code division multiple access network using single‐hop relaying

This paper is concerned with channel estimation and data detection for a cellular multi‐carrier code division multiple access network using single‐hop relaying in the presence of frequency selective fading channels. The proposed expectation–maximization (EM) algorithm was used to jointly estimate both the coefficients of the channel between a relay and a base station and the data. EM algorithm is particularly suited to multi‐carrier code division multiple access systems because they have multi‐carrier signal format. The considered network uses single‐hop relaying technique to provide a higher quality transmission to the users with low quality channels. The base station (managing mechanism) gives them an opportunity to send their messages via the users with high quality channels in a time sharing mode. The performance of the proposed EM algorithm, with and without hopping and with cooperative communication technique, was analyzed by a computer simulation, and the results are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

A co-designed coding,modulation and equalization scheme for the transmission of 155-52 Mbit/s data over a 72 MHz intelsat transponder. Part 2: Equalization

This paper reports on the application of co-designed coding, modulation and equalization techiques to an INTELSAT requirement for transmitting 155-52 Mbit/s data over a 72 MHz satellite channel. A specific solution as regards coding, modulation and equalization is proposed and analysed that differs from ‘standard’ concatenation in that the inner decoder integrates equalization, modulation and coding. In Part 2, a novel technique for integrating decision feedback equalization into the inner decoder is described. The gains in integrating the coding and equalization are shown to be significant for channels that need equalizing.     

A co-designed coding,modulation and equalization scheme for the transmission of 155-52 Mbit/s data over a 72 MHz intelsat transponder. Part 1: Coding and modulation performance

This paper reports on the application of co-designed coding, modulation and equalization techniques to an INTELSAT requirement for transmitting 155-52 Mbit/s data over a 72 MHz satellite channel. A specific solution as regards coding, modulation and equalization is proposed and analysed that differs from ‘standard’ concatenation in that the inner decoder integrates equalization, modulation and coding. In Part 1 results of extensive computer simulations are presented, examining the effect of adjacent channel interference, co-channel interference, non-linear distortion in representative ground and space TWTAs, multiplexers and filter distortion. In Part 2 a novel technique for integrating decision feedback equalization into the inner decoder is described. The gains in integrating the coding and equalization are shown to be significant for channels that need equalizing.