无线传输中短码长喷泉码的度分布优化算法

数字喷泉码是针对大规模网络数据分发而提出的一种新的信道编码方式。度分布是决定数字喷泉码译码性能的关键因素。为提高译码性能,针对应用于无线信道的喷泉码提出了一种度分布优化的算法。首先,根据理想孤子分布和鲁棒孤子分布产生度值序列,然后将该度值序列截短,在此基础上根据优化算法求解该序列中每个度值的最优概率,最后得到优化的度分布。仿真结果表明,本算法产生的度分布进行编译码产生的误码率低于鲁棒孤子分布和固定度分布,提高了译码性能。     

Antecedents of emotional attachment of social media users

Emotional attachment has been documented to be an effective basis for consumer loyalty behaviors in many contexts; however, not much has been offered for new service formats enabled by information technology. This study explores the emotional attachment of social media users in terms of personality traits of users and websites. Drawing on literature on brand personality and brand–self congruence, this research proposes that a match between user’s individual personality and the personality traits of the digital artifacts promotes affective connection to social media websites. The social media, to which the user becomes emotionally attached, therefore becomes part of one’s self-definition and representation in the digital world. Self-expressiveness is also investigated as a motivational driver that helps users form such an emotional bond. Individuals with higher motivation to express themselves are more likely to develop an emotional attachment to social networking sites, exhibit loyal behavior, and experience a stronger effect than self-website congruence on emotional attachment. Results of this research provide support to the proposed relationships. Theoretical and managerial implications are elaborated in the discussion.     

Factors affecting attitudes and behavioural intention towards social networking advertising: a case of Facebook users in South Korea

This study examined factors (e.g., ad values and social networking advertising characteristics) influencing consumers' attitudes and behavioural intention towards three types of social networking advertising (SNA) on Facebook – home page ad, social impression ad, and organic impression ad. Findings demonstrate that peer influence had the most significant impacts on attitude and behavioural intention across all types of SNA. The significant interaction term of invasiveness and privacy concern indicates that both attitude and behavioural intention were diminished, particularly when perceived invasiveness and privacy concern were high simultaneously. In addition, results suggest that attitudes towards the ad played a mediating role between SNA characteristics and behavioural intention. Lastly, among the types of SNA, consumers preferred organic impression ads that featured friends' names on their newsfeed more than paid ads located on the sidebar of their Facebook pages.     

Selling trust in cyber space: social networking service (SNS) providers and social capital amongst netizens in South Korea

Abstract

Apart from excessive bonding amongst co-ethnics, social capital studies have sparsely discussed the negative effects of social capital, including excessive collective actions towards downward social mobility (e.g. imprisonment of social and political elites). As Bourdieu has noted, social capital can conflate problems of upward social mobility through various glass ceilings in the reproduction of elite power groups. However, it is also important to notice that less fortunate groups can debunk the dominant elite social network by participating excessively in social networking service (SNS) platforms, where they exchange distorted information about the elites to organize collective actions towards their downward social mobility. Gleaned from the recent cases of ferry sinking and candlelight vigilance in South Korea, SNS providers can sell trust in cyber space that can be easily transformed into social capital for collective character assassinations, political demonstrations, and economic sabotages at workplace. Based on the big data gathered from Naver, one of the leading SNS providers in South Korea, we find that Naver provides SNS users with a rare opportunity to encounter myriad opinion groups who will over time converge into one or two similar opinion groups that can be easily mobilized towards collective actions. Selling trust in cyber space on the internet and mobile devices is a unique commercial development in South Korea and its neighbouring countries, including Japan and Taiwan.     

空中异构战术网络IP通信架构及协议开销分析

空中异构战术无线网络由多种不同类型的无线数据链网络构成,IP通信技术可有效解决空中平台异构无线网络的互联互通问题。给出了空中异构战术无线网络模型,并根据不同类型的无线数据链网络特点,分析了端到端通信协议栈关系以及不同无线数据链网络间协议转换与适配方式。探讨了网络静态和动态IP地址分配方法以及网络的路由架构与寻址方式,提出了不同无线数据链网络间IP报文传输的打包方式。对传输的开销性能仿真对比分析表明,基于通用成帧协议的打包方式的协议开销性能较优。     

适用于宽带网络波形的基于定价策略的时隙选择

针对宽带网络波形（Wideband Networking Waveform,WNW）的多信道二维时频资源,以减小网络资源浪费为优化目标,提出了一种基于定价策略的时隙选择方法（Pricing Strategy Based Slot Selection,PSSS）。该方法通过接纳控制保障资源分配的公平性,采用对偶优化建模与椭圆搜索法实现最优的时隙选择。理论分析证明该方法能够在多项式级别时间复杂度内搜索到时隙选择的最优解。仿真结果表明,提出的PSSS算法通过较低资源浪费获得了较低的容量冗余度,能够有效地解决WNW多信道网络的时隙选择问题。     

无线Ad Hoc网络中基于活跃节点数预测的时隙ALOHA算法

针对采用时隙ALOHA算法的无线Ad Hoc网络,考虑数据包到达的动态性与数据包传输的随机性,以最大化吞吐量为目标,同时满足数据队列稳定性,构建了关于接纳控制与竞争接入的随机优化问题。由于在时隙ALOHA算法中数据包传输的最优概率取决于无线Ad Hoc网络中数据队列非空的活跃节点数,提出了一种基于活跃节点数预测的时隙ALOHA算法。该算法要求无线Ad Hoc网络中的所有发送节点实时地侦听通信信道的忙闲状态,计算基于信道状态的活跃节点数条件期望,从而动态地预测无线Ad Hoc网络在不同时刻的活跃节点数,达到网络节点依据局部网络状态信息自适应地优化数据包传输概率的目的。仿真结果表明,所提算法能够有效估计无线Ad Hoc网络在每个时隙的活跃节点数,从而显著提升网络吞吐量并且降低数据包的平均排队时延。     

基于BWAS的无线传感器网络静态分簇路由算法

为提高路径搜索效率,避免动态分簇较多的能量消耗,提出了基于最优-最差蚂蚁系统(BWAS )的无线传感器 网络静态分簇路由算法。BWAS是对蚁群算法的改进,在路径搜寻过程中评价出最优最差蚂蚁 ,引入奖惩机制,加快了路径搜索速度。通过无线传感器网络静态分簇、簇内动态选举簇头 ,在簇头节点间运用BWAS算法搜寻从簇头节点到汇聚节点的多跳最优路径,能减少路径寻优 能量消耗,实现均衡能量管理,延长网络寿命,且具有较强的鲁棒性。通过与基于BWAS的 动态分簇和基于蚁群算法的动态分簇路由的仿真实验相比较,证实了本算法的有效性。     

无线传感器网络密钥管理研究进展

分析了当前无线传感器网络密钥管理协议设计中所存在的主要问题,在对具有代表性 的最新研究成果进行系统论述的基础上,全面分析了其利弊以及适应性问题。考虑到传感器 网络应用背景的细化和结构、功能的多元化,提出了今后的研究方向。     

Entering the mobile service market via mobile platforms: Qualcomm's BREW platform and Nokia's Preminet platform

The mobile telecommunication market has evolved from simple voice to multimedia services. In the past, the primary players in mobile services were local operators in different countries; international telecommunication vendors, such as Qualcomm and Nokia, were seldom involved in the mobile service market. In order to enter this market, Qualcomm and Nokia have separately introduced their mobile application platforms, called respectively BREW and Preminet. This paper examines how the two companies attempt to share the mobile service market through their mobile platforms and internationalized business models. This paper also analyzes their mobile platforms’ business models and their strategic implications.