Mobile ad hoc networking: imperatives and challenges

Mobile ad hoc networks (MANETs) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary, “ad-hoc” network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-existing communication infrastructure, e.g., disaster recovery environments. Ad hoc networking concept is not a new one, having been around in various forms for over 20 years. Traditionally, tactical networks have been the only communication networking application that followed the ad hoc paradigm. Recently, the introduction of new technologies such as the Bluetooth, IEEE 802.11 and Hyperlan are helping enable eventual commercial MANET deployments outside the military domain. These recent evolutions have been generating a renewed and growing interest in the research and development of MANET. This paper attempts to provide a comprehensive overview of this dynamic field. It first explains the important role that mobile ad hoc networks play in the evolution of future wireless technologies. Then, it reviews the latest research activities in these areas, including a summary of MANET’s characteristics, capabilities, applications, and design constraints. The paper concludes by presenting a set of challenges and problems requiring further research in the future.     

Virtual space, real identity: Exploring cultural identity of Chinese Diaspora in virtual community

With the advent of globalization, the movement of immigrants has crossed the borders and the question of identity has been more and more salient in the modern society. Struggling in different cultural frames, Diasporas’ cultural identities are constructed through the interaction between what Hall called similarity and difference in the process of displacement and relocation.

The deterritorialization in the era of globalization calls the traditional notion of “community” into question. Scattered across the western hemisphere, the new Chinese Diaspora are gathering in the virtual communities to grab news, to comment on issues, and to negotiate their identities in an alien culture.

Interviews with Chinese Diaspora in the North America show that the negotiation of different cultural values and practices results in the fragmented and hybridized cultural identity among them in virtual communities. This exploration of interpersonal experiences also shows that the symbiotic relationship between the physical community and the virtual community forges and strengthens such discursive cultural identity.     

Passive neighbor discovery with social recognition for mobile ad hoc social networking applications

Wireless Networks - Neighbor discovery is the cornerstone of the mobile social applications over mobile ad hoc networks. Most current neighbor discovery protocols adopt a carefully designed...     

Mobile computing and ubiquitous networking: concepts, technologies and challenges

With the rapidly increasing penetration of laptop computers, which are primarily used by mobile users to access Internet services, support of Internet services in a mobile environment become an increasing need. The opportunities emerging from these technologies give rise to new paradigms such as mobile computing and ubiquitous networking. However, there are numerous challenges such as reliability and quality of service, infrastructure costs, energy efficiency of mobile devices, among others. This paper analyzes concepts, technologies and challenges related to these paradigms. The major challenges include mobility, disconnection and scale, new information medium and new resource limitations. As a fundamental characteristics of mobile environments, the user can see the same computing environment regardless of his or her current location. The most exciting promises of mobile computing and ubiquitous networking stay an entire new class of applications and potential new massive markets combining personal computing and consumer electronics.     

移动通信市场在危机中求发展

2001年对全世界的通信产业而言都是艰难与沮丧的一年，移动通信厂商和运营商几乎都陷入了危机之中。爱立信总裁柯德川甚至认为，过去的一年可能是电信史上最艰苦的一年。但是坏事有时也会变成好事，人们在逆境中开始重新评估自己的计划和策略，要么继续打一场混战，要么和平共处，共谋出路，另寻商机。曾几何时，移动通信常被媒体誉为“最火爆的”一枝独秀。 从1G到2G的演变和发展，如顺水推舟，一日千里；但是当从2G演变到3G时却风云突变，不管在北美、欧洲还是亚洲，部署3G网络简直是如履薄冰，寸步难行。关于通信市场的预测，业界普遍…     

FreeWalk: a 3D virtual space for casual meetings

A meeting environment for casual communication in a networked community, FreeWalk provides a 3D common area where everyone can meet and talk freely. FreeWalk represents participants as 3D polygon pyramids, on which their live video is mapped. Voice volume remains proportional to the distance between sender and receiver. For evaluation, we compared communications in FreeWalk to a conventional desktop videoconferencing system and a face-to-face meeting     

Coping with fear and guilt using mobile social networking applications: Knowledge hiding,loafing, and sharing

Mobile social networking applications (MSNAs) are readily attractive for supporting interactions and collaborations between people in a variety of mobile environments due to their low-cost and ubiquity. Departing from existing research, this study focuses on the influence of negative emotions in the context of MSNA use. Integrating theories of coping, regulatory focus, and guilt, this study proposes a research model to explore how people cope with fear (self-referenced fear and other-referenced fear) and guilt using three coping strategies (knowledge sharing, hiding, and knowledge contribution loafing) in the context of MSNAs. Also involved are two moderators (promotion-focused and prevention-focused) that exhibit different tendencies in strategy choices, thus generating a varying of behavioral results when tackling fear and guilt. Data collected from 496 members of LINE groups support most of our proposed model, which conjectures the differential effects of self-referenced fear, other-referenced fear, and guilt on coping strategies in terms of regulatory focus. Notably, this study is among the very first to explore the concerns and affects of fear and guilt in the context of using MSNAs, with rich theoretical and practical implications.     

Effects of brand anthropomorphism on consumer-brand relationships on social networking site fan pages: The mediating role of social presence

This study aimed to investigate the effects of brand anthropomorphism on consumer-brand relationships in a social media marketing context. We hypothesized that anthropomorphism on a brand’s Facebook fan page can strengthen the relationships between brands and consumers by yielding both social presence and a positive inference regarding the brand’s quality as a relationship partner. Our longitudinal experiment confirmed the effects of brand anthropomorphism on consumer-brand relationships on social media and the mediating role of social presence. The results suggest that when the anthropomorphized brand had relationships with consumers, a favorable attitude was shown toward the brand. Further, the participants perceived the anthropomorphized brand as a trustworthy relationship partner, giving more “Likes” for the posts from the anthropomorphized brand than those from the non-anthropomorphized brand. Further, the results confirmed that these favorable relationships were maintained even after the participants became aware of a brand transgression.     

Survey on mobile social networking in proximity (MSNP): approaches,challenges and architecture

Recently, mobile social networks (MSN) have gained tremendous attention, which free users from face-to-monitor life, while still can share information and stay in touch with their friends on the go. However most MSN applications regard mobile terminals just as entry points to existing social networks, in which centralized servers (for storage and processing of all application/context data) and continual Internet connectivity are prerequisites for mobile users to exploit MSN services, even though they are within proximity area (like campus, event spot, and community, etc.), and can directly exchange data through various wireless technologies (e.g., Bluetooth, WiFi Direct, etc.). In this paper, we focus on mobile social networking in proximity (MSNP), which is explicitly defined in our paper as: MSNP is wireless peer-to-peer (P2P) network of spontaneously and opportunistically connected nodes, and uses geo-proximity as the primary filter in determining who is discoverable on the social network. In this paper, first, primary support approaches related to MSNP available in literature, are summarized and compared, including MSN, mobile P2P and opportunistic networks. And then, we offer the special characteristics of MSNP, open issues and potential solutions. A networking technologies and platform independent architecture is proposed for developing MSNP applications, and proof-of-concept implementation of WiFi direct based MSNP application is also provided. Our primary goal is to identify the characteristics, technical challenges and potential solutions for future MSNP applications, capable to flexibly adapt to different application domains and deployment requirements.     

基于块空时分组编码虚拟MIMO中继传输方案

以LTE TDD系统上行链路为研究对象,提出了一种基于块空时分组编码的虚拟MIMO中继传输方案,并推导给出基站低复杂度的虚拟MIMO系统接收机检测算法。研究表明:本传输方案具有提高小区边缘及网络覆盖盲区用户链路传输可靠性的特性,同时可克服传统中继方案频谱效率降低的缺点。     

The effects of social networks on the assessment of virtual learning environments: A study for social sciences degrees

This paper deepens in the study of the appropriateness of virtual learning environments through the use and value of social networks by college students, considering the reliability, confidence and experience of the Internet. The study develop a comprehensive structural equation model conducted among 381college students of different Social Sciences degrees of the University of A Coruna (Spain). The results show that both topical social network and the Internet have a significant influence on college students’ virtual learning environment assessment, regardless the area of study. The analysis also discloses the potential utility of the above interactions on virtual learning environments in terms of downloading of material, improvement in learning efficiency and usefulness of contents, functions and supplement of other learning ICT tools. Findings reveal that the implementation of educational policies that allow adapting virtual learning environments to college students’ preferences are required.     

Supportive communication on social networking sites: The impact of post valence and relational closeness on support provision

This project adopted a mixed-method approach to examine relational and contextual factors that influence people’s intention to provide support on SNSs. A pilot survey examined people’s use of SNSs for supportive exchange. Facebook was found to be the most used SNS for support seeking. People responded more often to a close friend’s support-seeking post than to an acquaintance’s post. Building on the findings in the pilot study, a main experiment was conducted to examine the impact of valence of a support seeker’s previous posts and relational closeness on viewers’ perceptions of the support seeker and their intention to provide support. Findings showed that valence of a support seeker’s previous posts affects viewers’ liking and perceived need for support in opposite directions, which in turn influences viewers’ intended support provision. In addition, relational closeness positively affects viewers’ liking of a support seeker and thus their intention to provide support.     

Ad hoc networking with directional antennas: a complete system solution

Directional antennas offer tremendous potential for improving the performance of ad hoc networks. Harnessing this potential, however, requires new mechanisms at the medium access and network layers for intelligently and adaptively exploiting the antenna system. While recent years have seen a surge of research into such mechanisms, the problem of developing a complete ad hoc networking system, including the unique challenge of real-life prototype development and experimentation has not been addressed. In this paper, we present utilizing directional antennas for ad hoc networking (UDAAN). UDAAN is an interacting suite of modular network- and medium access control (MAC)-layer mechanisms for adaptive control of steered or switched antenna systems in an ad hoc network. UDAAN consists of several new mechanisms-a directional power-controlled MAC, neighbor discovery with beamforming, link characterization for directional antennas, proactive routing and forwarding-all working cohesively to provide the first complete systems solution. We also describe the development of a real-life ad hoc network testbed using UDAAN with switched directional antennas, and we discuss the lessons learned during field trials. High fidelity simulation results, using the same networking code as in the prototype, are also presented both for a specific scenario and using random mobility models. For the range of parameters studied, our results show that UDAAN can produce a very significant improvement in throughput over omnidirectional communications.     

Mobile social networks as quality of life technology for people with severe mental illness

Currently, assistive technology focuses on promoting greater independence for people with disabilities by enabling them to perform tasks on a personal basis. For certain disabilities, such as cognitive impairment, the requirements for dual interface development must address the needs of target users, as well as their caregivers. Assistive technology that leverages networks of caregivers, who are nomadic or remain on the go constantly, has not been developed into useful services or even explored systematically. In this article, first we propose a general architecture of mobile social networks where individuals in the networks form a virtual community, conversing and connecting with one another, based on mobile communication. Second, we describe an implementation of mobile social networks in collaboration with a supported employment program established for people with severe mental illness     

Systems with infinite-dimensional state space: The Hilbert space approach

The control of infinite-dimensional systems has received much attention from engineers and even mathematicians. Realizability although first considered in [4] has been ignored until recently. Ironically enough while state-space systems theory was developing in the early 1960's a mathematical study of scattering and of non-self-adjoint operators produced a parallel theory which was infinite dimensional from the beginning. When the close relationship between the two subjects became known time invariant infinite-dimensional systems theory advanced quickly and at a general level it now seems reasonably complete. This paper describes the connection between mathematical scattering and systems. It then gives a thorough treatment of infinite-dimensional time invariant continuous time systems. The last section lists recent scattering results which might be of engineering interest.     

School performance,social networking effects,and learning of school children: Evidence of reciprocal relationships in Abu Dhabi

This study uses structural equations modeling to test a hypothetical social network model with applications to a sample of 34,896 school children in Abu Dhabi. The main independent constructs in the model are related to children’s attitude with regard to social networking, reasons for using social networks, things done on social networks, and topics used. The dependent constructs cover perceived school performance and social effects of social networking. The study will describe the relations among the various constructs. The effect of other variables, such as parental knowhow, is also investigated. Our work has improved our insight in the social networking model. Results support the idea of reciprocal relations among perceived performance, learning from social networking, and the effect of social networking. Evidence for a model that includes opposite pathways implies that the problem of social networking constructs, its antecedents, and possible consequences should be examined with caution.     

Correction to: User interest community detection on social media using collaborative filtering

Wireless Networks - The article User interest community detection on social media using collaborative filtering, written by Liang Jiang, Leilei Shi, Lu Liu, Jingjing Yao, Moses Edward Ali.     

A student's perspective: getting real with virtual reality

As with many up and coming technologies, the road to wide acceptance is not always smooth. Virtual reality (VR) is one such technology whose bumpy ascent is well underway. VR is not all that new but the steady price/performance gains for computational power have helped it gain a broader base of applications and even a little popularity along the way. The author's current research is one example of how VR can be used as an analysis as well as a visualization tool. He is developing interactive scenarios where the user can pose "what if?" questions in a VR environment and the VR environment will respond with an array of possibilities. The user will then be able to experience and better assess the impacts of each alternative. The interactive aspects of VR make it an ideal platform for developing scenarios across a broad range of applications.