In this paper, we review the background and state-of-the-art of big data. We first introduce the general background of big data and review related technologies, such as could computing, Internet of Things, data centers, and Hadoop. We then focus on the four phases of the value chain of big data, i.e., data generation, data acquisition, data storage, and data analysis. For each phase, we introduce the general background, discuss the technical challenges, and review the latest advances. We finally examine the several representative applications of big data, including enterprise management, Internet of Things, online social networks, medial applications, collective intelligence, and smart grid. These discussions aim to provide a comprehensive overview and big-picture to readers of this exciting area. This survey is concluded with a discussion of open problems and future directions.

Big Data: A Survey

With the rapid deployment of new wireless devices and applications, the last decade has witnessed a growing demand for wireless radio spectrum. However, the fixed spectrum assignment policy becomes a bottleneck for more efficient spectrum utilization, under which a great portion of the licensed spectrum is severely under-utilized. The inefficient usage of the limited spectrum resources urges the spectrum regulatory bodies to review their policy and start to seek for innovative communication technology that can exploit the wireless spectrum in a more intelligent and flexible way. The concept of cognitive radio is proposed to address the issue of spectrum efficiency and has been receiving an increasing attention in recent years, since it equips wireless users the capability to optimally adapt their operating parameters according to the interactions with the surrounding radio environment. There have been many significant developments in the past few years on cognitive radios. This paper surveys recent advances in research related to cognitive radios. The fundamentals of cognitive radio technology, architecture of a cognitive radio network and its applications are first introduced. The existing works in spectrum sensing are reviewed, and important issues in dynamic spectrum allocation and sharing are investigated in detail.

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Advances in cognitive radio networks: A survey

The Grid 2: Blueprint for a New Computing Infrastructure

The solid-state lighting is revolutionizing the indoor illumination. Current incandescent and fluorescent lamps are being replaced by the LEDs at a rapid pace. Apart from extremely high energy efficiency, the LEDs have other advantages such as longer lifespan, lower heat generation, and improved color rendering without using harmful chemicals. One additional benefit of LEDs is that they are capable of switching to different light intensity at a very fast rate. This functionality has given rise to a novel communication technology (known as visible light communication—VLC) where LED luminaires can be used for high speed data transfer. This survey provides a technology overview and review of existing literature of visible light communication and sensing. This paper provides a detailed survey of 1) visible light communication system and characteristics of its various components such as transmitter and receiver; 2) physical layer properties of visible light communication channel, modulation methods, and MIMO techniques; 3) medium access techniques; 4) system design and programmable platforms; and 5) visible light sensing and application such as indoor localization, gesture recognition, screen-camera communication, and vehicular networking. We also outline important challenges that need to be addressed in order to design high-speed mobile networks using visible light communication.

Visible Light Communication, Networking, and Sensing: A Survey, Potential and Challenges

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Art of electronics

This paper presents a holistic system to scale up the teaching and learning of vocabulary words of American Sign Language (ASL). The system leverages the most recent mixed-reality technology to allow the user to perceive her own hands in an immersive learning environment with first- and third-person views for motion demonstration and practice. Precise motion sensing is used to record and evaluate motion, providing real-time feedback tailored to the specific learner. As part of this evaluation, learner motions are matched to features derived from the Hamburg Notation System (HNS) developed by sign-language linguists. We develop a prototype to evaluate the efficacy of mixed-reality-based interactive motion teaching. Results with 60 participants show a statistically significant improvement in learning ASL signs when using our system, in comparison to traditional desktop-based, non-interactive learning. We expect this approach to ultimately allow teaching and guided practice of thousands of signs.

Teaching American Sign Language in Mixed Reality

StarLight is an infrastructure-based sensing system that reuses light emitted from ceiling LED panels to reconstruct fine-grained user skeleton postures continuously in real time. It leverages only a few (e.g., 20) photodiodes at optimized locations on the floor to capture low-level visual cues (light blockage information), with neither invasive cameras nor on-body sensors. It aggregates the blockage information of different light rays and identifies the best-fit 3D skeleton postures. Experiments show that StarLight achieves 13.6° mean angular error for five body joints and reconstructs a mobile skeleton at a high frame rate (40 FPS). StarLight presents a new unobtrusive sensing paradigm to augment today's mobile sensing for continuous and accurate behavioral monitoring.

Practical Human Sensing in the Light

Wireless growth has been limited by the shortage of radio spectrum. While the spectrum assigned to legacy technologies remain unused, new prominent technologies such as Mesh/WiFi networks are forced to crowd into a small unlicensed band, suffering from significant interference and degraded performance. Using economic incentives, dynamic spectrum auctions redistribute spectrum to make it available to new technologies while providing financial benefits to legacy owners. In this paper, we investigate the performance of dynamic spectrum auctions under traffic dynamics. Using measured traffic traces from deployed WiFi access points, we evaluate the advantages and artifacts of dynamic auctions over plain channel sharing, and investigate the impact of bidding formats and auction intervals. Our results show that short-term dynamic auctions with traffic-aware bidding can significantly improve system throughput and provide bidders with cost-effective spectrum usage.

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Traffic-Driven Dynamic Spectrum Auctions

Stress is an important aspect of human psychology. Many measures of stress have been developed over the years, but different issues exist for most of these measures. This study introduces the Mobile Photographic Stress Meter (MPSM), a new way to measure stress in which a user simply selects an image that best captures his or her stress level. Such a tool allows researchers to quickly measure stress in real time and in natural environments less onerous for the user. Our results show that MPSM is a valid measure of stress. Users find it easy and actually enjoyable to use. Our results also show that MPSM is strongly correlated with the Perceived Stress Scale, a validated multi-item stress scale. The correlation has an r-value of 0.5559 and a p-value of less than 0.001. We conclude that MPSM can be applied effectively in research experiments and advance the research on stress.

The mobile photographic stress meter (MPSM): a new way to measure stress using images

In this paper we propose a reputation based client puzzle scheme included in a security framework to enhance base station security against denial-of-service attacks in the scenario of wireless sensor network. Through flexibly adjusting the difficulty level of puzzle according to each node's reputation value, we make malicious nodes with low reputation value face harder puzzle, rendering their attacks tougher while limiting extra overhead to normal nodes. We analyze our security framework in the specific case of SPINS, and conduct simulation to evaluate its effectiveness

Xia Zhou

Papers

Teaching American Sign Language in Mixed Reality

Practical Human Sensing in the Light

Traffic-Driven Dynamic Spectrum Auctions

The mobile photographic stress meter (MPSM): a new way to measure stress using images

Enhancing Base Station Security Against DoS Attacks in Wireless Sensor Networks