We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

The recently developed depth sensors, e.g., the Kinect sensor, have provided new opportunities for human-computer interaction (HCI). Although great progress has been made by leveraging the Kinect sensor, e.g., in human body tracking, face recognition and human action recognition, robust hand gesture recognition remains an open problem. Compared to the entire human body, the hand is a smaller object with more complex articulations and more easily affected by segmentation errors. It is thus a very challenging problem to recognize hand gestures. This paper focuses on building a robust part-based hand gesture recognition system using Kinect sensor. To handle the noisy hand shapes obtained from the Kinect sensor, we propose a novel distance metric, Finger-Earth Mover's Distance (FEMD), to measure the dissimilarity between hand shapes. As it only matches the finger parts while not the whole hand, it can better distinguish the hand gestures of slight differences. The extensive experiments demonstrate that our hand gesture recognition system is accurate (a 93.2% mean accuracy on a challenging 10-gesture dataset), efficient (average 0.0750 s per frame), robust to hand articulations, distortions and orientation or scale changes, and can work in uncontrolled environments (cluttered backgrounds and lighting conditions). The superiority of our system is further demonstrated in two real-life HCI applications.

/pdf/robust-part-based-hand-gesture-recognition-using-kinect-3wtirf4jsv.pdf

Robust Part-Based Hand Gesture Recognition Using Kinect Sensor

Aspects of the subject disclosure may include, for example, receiving, by a feed point of a dielectric antenna, electromagnetic waves from a dielectric core coupled to the feed point without an electrical return path, where at least a portion of the dielectric antenna comprises a conductive surface, directing, by the feed point, the electromagnetic waves to a proximal portion of the dielectric antenna, and radiating, via an aperture of the dielectric antenna, a wireless signal responsive to the electromagnetic waves being received at the aperture. Other embodiments are disclosed.

Method and apparatus for coupling an antenna to a device

A distributed antenna and backhaul system provide network connectivity for a small cell deployment. Rather than building new structures, and installing additional fiber and cable, embodiments described herein disclose using high-bandwidth, millimeter-wave communications and existing power line infrastructure. Above ground backhaul connections via power lines and line-of-sight millimeter-wave band signals as well as underground backhaul connections via buried electrical conduits can provide connectivity to the distributed base stations. An overhead millimeter-wave system can also be used to provide backhaul connectivity. Modules can be placed onto existing infrastructure, such as streetlights and utility poles, and the modules can contain base stations and antennas to transmit the millimeter-waves to and from other modules.

Backhaul link for distributed antenna system

A distributed antenna system is provided that frequency shifts the output of one or more microcells to a 60 GHz or higher frequency range for transmission to a set of distributed antennas. The cellular band outputs of these microcell base station devices are used to modulate a 60 GHz (or higher) carrier wave, yielding a group of subcarriers on the 60 GHz carrier wave. This group will then be transmitted in the air via analog microwave RF unit, after which it can be repeated or radiated to the surrounding area. The repeaters amplify the signal and resend it on the air again toward the next repeater. In places where a microcell is required, the 60 GHz signal is shifted in frequency back to its original frequency (e.g., the 1.9 GHz cellular band) and radiated locally to nearby mobile devices.

Remote distributed antenna system

Planet-scale video Content Delivery Networks (CDNs) deliver a significant fraction of the entire Internet traffic. Effective caching at the edge is vital for the feasibility of these CDNs, which can otherwise incur significant monetary costs and resource overloads in the Internet.We analyze the challenges and requirements for video caching on these CDNs which cannot be addressed by standard solutions. We develop multiple algorithms for caching in these CDNs: (i) An LRU-based baseline solution to address the requirements, (ii) an intelligent ingress-efficient algorithm, (iii) an offline cache aware of future requests (greedy) to estimate the maximum caching efficiency we can expect from any online algorithm, and (iv) an optimal offline cache (for limited scales). We use anonymized actual data from a large-scale, global CDN to evaluate the algorithms and draw conclusions on their suitability for different settings.

http://msrg.org/publications/pdf_files/2014/MJ-EuroSys14-Content_delivery_networks,_video.pdf

Caching in video CDNs: building strong lines of defense

Peer-to-peer (P2P) systems generate a major fraction of the current Internet traffic, and they significantly increase the load on ISP networks and the cost of running and connecting customer networks (e.g., universities and companies) to the Internet. To mitigate these negative impacts, many previous works in the literature have proposed caching of P2P traffic, but very few (if any) have considered designing a caching system to actually do it. This paper demonstrates that caching P2P traffic is more complex than caching other Internet traffic, and it needs several new algorithms and storage systems. Then, the paper presents the design and evaluation of a complete, running, proxy cache for P2P traffic, called pCache. pCache transparently intercepts and serves traffic from different P2P systems. A new storage system is proposed and implemented in pCache. This storage system is optimized for storing P2P traffic, and it is shown to outperform other storage systems. In addition, a new algorithm to infer the information required to store and serve P2P traffic by the cache is proposed. Furthermore, extensive experiments to evaluate all aspects of pCache using actual implementation and real P2P traffic are presented.

/pdf/design-and-evaluation-of-a-proxy-cache-for-peer-to-peer-4hbdn1ef1c.pdf

Design and Evaluation of a Proxy Cache for Peer-to-Peer Traffic

With the rapid increase in the demand for multimedia services, securing the delivery of multimedia content has become an important issue. Accordingly, the problem of multimedia stream authentication has received considerable attention by previous research and various solutions have been proposed. However, these solutions have not been rigorously analyzed and contrasted to each other, and thus their relative suitability for different streaming environments is not clear. This article presents comprehensive analysis and comparison among different schemes proposed in the literature to authenticate multimedia streams. Authentication schemes for nonscalable and scalable multimedia streams are analyzed. To conduct this analysis, we define five important performance metrics, which are computation cost, communication overhead, receiver buffer size, delay, and tolerance to packet losses. We derive analytic formulas for these metrics for all considered authentication schemes to numerically analyze their performance. In addition, we implement all schemes in a simulator to study and compare their performance in different environments. The parameters for the simulator are carefully chosen to mimic realistic settings. We draw several conclusions on the advantages and disadvantages of each scheme. We extend our analysis to authentication techniques for scalable streams. We pay careful attention to the flexibility of scalable streams and analyze its impacts on the authentication schemes. Our analysis and comparison reveal the merits and shortcomings of each scheme, provide guidelines on choosing the most appropriate scheme for a given multimedia streaming application, and could stimulate designing new authentication schemes or improving existing ones. For example, our detailed analysis has led us to design a new authentication scheme that combines the best features of two previous schemes.

/pdf/authentication-schemes-for-multimedia-streams-quantitative-rpycfdjf87.pdf

Authentication schemes for multimedia streams: Quantitative analysis and comparison

The large prevalence of multimedia systems in recent years makes the security of multimedia communications an important and critical issue. We study the problem of securing the delivery of scalable video streams so that receivers can ensure the authenticity of the video content. Our focus is on recent scalable video coding (SVC) techniques, such as H.264/SVC, which can provide three scalability types at the same time: temporal, spatial, and visual quality. This three-dimensional scalability offers a great flexibility that enables customizing video streams for a wide range of heterogeneous receivers and network conditions. This flexibility, however, is not supported by current stream authentication schemes in the literature. We propose an efficient and secure authentication scheme that accounts for the full scalability of video streams, and enables verification of all possible substreams that can be extracted from the original stream. In addition, we propose an algorithm for minimizing the amount of authentication information that need to be attached to streams. The proposed authentication scheme supports end-to-end authentication, in which any third-party entity involved in the content delivery process, such as stream adaptation proxies and caches, does not have to understand the authentication mechanism. Our simulation study with real video traces shows that the proposed authentication scheme is robust against packet losses, incurs low computational cost for receivers, has short delay, and adds low communication overhead. Finally, we implement the proposed authentication scheme as an open source library called svcAuth, which can be used as a transparent add-on by any multimedia streaming application.

/pdf/authentication-of-scalable-video-streams-with-low-22u9e3ql42.pdf

Authentication of Scalable Video Streams With Low Communication Overhead

Global video content distribution networks (CDNs) serve a significant fraction of the entire Internet traffic. Effective caching at the edge is vital for the feasibility of these CDNs, which can otherwise incur substantial costs and overloads in the Internet. We analyze the challenges and requirements for content caching on the servers of these CDNs which cannot be addressed by standard solutions. We design multiple algorithms for this problem: a LRU-based baseline to address the requirements; a flexible ingress-efficient algorithm; an offline cache aware of future requests (greedy) to estimate the maximum efficiency we can expect from any online algorithm; an optimal offline cache (for limited scales); and an adaptive ingress control algorithm for reducing the server’s peak upstream traffic. We use anonymized actual data from a global video CDN to evaluate the algorithms and draw conclusions on their suitability for different settings.

Kianoosh Mokhtarian

Papers

Caching in video CDNs: building strong lines of defense

Design and Evaluation of a Proxy Cache for Peer-to-Peer Traffic

Authentication schemes for multimedia streams: Quantitative analysis and comparison

Authentication of Scalable Video Streams With Low Communication Overhead

Flexible Caching Algorithms for Video Content Distribution Networks