bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring and Synthesizing Systems in Probabilistic Environments
Authors: Chatterjee Krishnendu , Henzinger Thomas A. , Jobstmann Barbara , Singh Rohit
Published: March 2015

The traditional synthesis question given a specification asks for the automatic construction of a system that satisfies the specification, whereas often there exists a preference order among the different systems that satisfy the given specification. Under a probabilistic assumption about the possible inputs, such a preference order is naturally expressed by a weighted automaton, which assigns to each word a value, such that a system is preferred if it generates a higher expected value. We solve the following optimal synthesis problem: given an omega-regular specification, a Markov chain that describes the distribution of inputs, and a weighted automaton that measures how well a system satisfies the given specification under the input assumption, synthesize a system that optimizes the measured value.

For safety specifications and quantitative measures that are defined by mean-payoff automata, the optimal synthesis problem reduces to finding a strategy in a Markov decision process (MDP) that is optimal for a long-run average reward objective, which can be achieved in polynomial time. For general omega-regular specifications along with mean-payoff automata, the solution rests on a new, polynomial-time algorithm for computing optimal strategies in MDPs with mean-payoff parity objectives. Our algorithm constructs optimal strategies that consist of two memoryless strategies and a counter. The counter is in general not bounded. To obtain a finite-state system, we show how to construct an ϵ-optimal strategy with a bounded counter, for all ϵ > 0. Furthermore, we show how to decide in polynomial time if it is possible to construct an optimal finite-state system (i.e., a system without a counter) for a given specification.

We have implemented our approach and the underlying algorithms in a tool that takes qualitative and quantitative specifications and automatically constructs a system that satisfies the qualitative specification and optimizes the quantitative specification, if such a system exists. We present some experimental results showing optimal systems that were automatically generated in this way.
Augmented Airbrush for Computer Aided Painting (CAP)
Authors: Shilkrot Roy , Maes Pattie , Paradiso Joseph A. , Zoran Amit
Published: March 2015

We present an augmented airbrush that allows novices to experience the art of spray painting. Inspired by the thriving field of smart tools, our handheld device uses 6DOF tracking, augmentation of the airbrush trigger, and a specialized algorithm to restrict the application of paint to a preselected reference image. Our device acts both as a physical spraying device and as an intelligent assistive tool, providing simultaneous manual and computerized control. Unlike prior art, here the virtual simulation guides the physical rendering (
inverse rendering
), allowing for a new spray painting experience with singular physical results. We present our novel hardware design, control software, and a user study that verifies our research objectives.
Reconfigurable Binding against FPGA Replay Attacks
Authors: Zhang Jiliang , Lin Yaping , Qu Gang
Published: March 2015

The FPGA replay attack, where an attacker downgrades an FPGA-based system to the previous version with known vulnerabilities, has become a serious security and privacy concern for FPGA design. Current FPGA intellectual property (IP) protection mechanisms target the protection of FPGA configuration bitstreams by watermarking or encryption or binding. However, these mechanisms fail to prevent replay attacks. In this article, based on a recently reported PUF-FSM binding method that protects the usage of configuration bitstreams, we propose to reconfigure both the physical unclonable functions (PUFs) and the locking scheme of the finite state machine (FSM) in order to defeat the replay attack. We analyze the proposed scheme and demonstrate how replay attack would fail in attacking systems protected by the reconfigurable binding method. We implement two ways to build reconfigurable PUFs and propose two practical methods to reconfigure the locking scheme. Experimental results show that the two reconfigurable PUFs can generate significantly distinct responses with average reconfigurability of more than 40%. The reconfigurable locking schemes only incur a timing overhead less than 1%.
Data-Driven Optimization of Order Admission Policies in a Digital Print Factory
Authors: Duan Qing , Zeng Jun , Chakrabarty Krishnendu , Dispoto Gary
Published: March 2015

On-demand digital print service is an example of a real-time embedded enterprise system. It offers mass customization and exemplifies personalized manufacturing services. Once a print order is submitted to the print factory by a client, the print service provider (PSP) needs to make a real-time decision on whether to accept or refuse this order. Based on the print factory's current capacity and the order's properties and requirements, an order is refused if its acceptance is not profitable for the PSP. The order is accepted with the most appropriate due date in order to maximize the profit that can result from this order. We have developed an automated learning-based order admission framework that can be embedded into an enterprise environment to provide real-time admission decisions for new orders. The framework consists of three classifiers: Support Vector Machine (SVM), Decision Tree (DT), and Bayesian Probabilistic Model (BPM). The classifiers are trained by history orders and used to predict completion status for new orders. A decision integration technique is implemented to combine the results of the classifiers and predict due dates. Experimental results derived using real factory data from a leading print service provider and Weka open-source software show that the order completion status prediction accuracy is significantly improved by the decision integration strategy. The proposed multiclassifier model also outperforms a standalone regression model.
Applying Pay-Burst-Only-Once Principle for Periodic Power Management in Hard Real-Time Pipelined Multiprocessor Systems
Authors: Chen Gang , Huang Kai , Buckl Christian , Knoll Alois
Published: March 2015

Pipelined computing is a promising paradigm for embedded system design. Designing a power management policy to reduce the power consumption of a pipelined system with nondeterministic workload is, however, nontrivial. In this article, we study the problem of energy minimization for coarse-grained pipelined systems under hard real-time constraints and propose new approaches based on an inverse use of the pay-burst-only-once principle. We formulate the problem by means of the resource demands of individual pipeline stages and propose two new approaches, a quadratic programming-based approach and fast heuristic, to solve the problem. In the quadratic programming approach, the problem is transformed into a standard quadratic programming with box constraint and then solved by a standard quadratic programming solver. Observing the problem is NP-hard, the fast heuristic is designed to solve the problem more efficiently. Our approach is scalable with respect to the numbers of pipeline stages. Simulation results using real-life applications are presented to demonstrate the effectiveness of our methods.
Scheduling a Video Transcoding Server to Save Energy
Authors: Song Minseok , Lee Yeongju , Park Jinhan
Published: March 2015

Recent popular streaming services such as TV Everywhere, N-Screen, and dynamic adaptive streaming over HTTP (DASH) need to deliver content to the wide range of devices, requiring video content to be transcoded into different versions. Transcoding tasks require a lot of computation, and each task typically has its own real-time constraint. These make it difficult to manage transcoding, but the more efficient use of energy in servers is an imperative. We characterize transcoding workloads in terms of deadlines and computation times, and propose a new dynamic voltage and frequency scaling (DVFS) scheme that allocates a frequency and a workload to each CPU with the aim of minimizing power consumption while meeting all transcoding deadlines. This scheme has been simulated, and also implemented in a Linux transcoding server, in which a frontend node distributes transcoding requests to heterogeneous backend nodes. This required a new protocol for communication between nodes, a DVFS management scheme to reduce power consumption and thread management and scheduling schemes which ensure that transcoding deadlines are met. Power measurements show that this approach can reduce system-wide energy consumption by 17% to 31%, compared with the Linux Ondemand governor.
Analysis and Detection of Fake Views in Online Video Services
Authors: Chen Liang , Zhou Yipeng , Chiu Dah Ming
Published: March 2015

Online video-on-demand(VoD) services invariably maintain a view count for each video they serve, and it has become an important currency for various stakeholders, from viewers, to content owners, advertizers, and the online service providers themselves. There is often significant financial incentive to use a robot (or a botnet) to artificially create fake views. How can we detect fake views? Can we detect them (and stop them) efficiently? What is the extent of fake views with current VoD service providers? These are the questions we study in this article. We develop some algorithms and show that they are quite effective for this problem.
Decoder-Complexity-Aware Encoding of Motion Compensation for Multiple Heterogeneous Receivers
Authors: Langroodi Mohsen Jamali , Peters Joseph , Shirmohammadi Shervin
Published: March 2015

For mobile multimedia systems, advances in battery technology have been much slower than those in memory, graphics, and processing power, making power consumption a major concern in mobile systems. The computational complexity of video codecs, which consists of CPU operations and memory accesses, is one of the main factors affecting power consumption. In this article, we propose a method that achieves near-optimal video quality while respecting user-defined bounds on the complexity needed to decode a video. We specifically focus on the motion compensation process, including motion vector prediction and interpolation, because it is the single largest component of computation-based power consumption. We start by formulating a scenario with a single receiver as a rate-distortion optimization problem and we develop an efficient decoder-complexity-aware video encoding method to solve it. Then we extend our approach to handle multiple heterogeneous receivers, each with a different complexity requirement. We test our method experimentally using the H.264 standard for the single receiver scenario and the H.264 SVC extension for the multiple receiver scenario. Our experimental results show that our method can achieve up to 97% of the optimal solution value in the single receiver scenario, and an average of 97% of the optimal solution value in the multiple receiver scenario. Furthermore, our tests with actual power measurements show a power saving of up to 23% at the decoder when the complexity threshold is halved in the encoder.
What Are the Most Important Factors for Accounting Information Quality and Their Impact on AIS Data Quality Outcomes?
Authors: Xu Hongjiang
Published: March 2015

The accounting information system (AIS) is one of the most critical systems in any organization. Data quality plays a critical role in a data-intensive, knowledge-based economy. The objective of this study is to identify the most important factors for accounting information quality and their impact on AIS data quality outcomes. The article includes an extensive literature review and summarizes studies in quality management, data quality, accounting information systems, and enterprise planning in helping to identify a set of critical success factors for data quality. The study uses empirical data to answer the research question and test the research hypothesis. Study results show that the top three most important factors that affect accounting information systems’ data quality are top management commitment, the nature of the accounting information systems (such as the suitability of the systems), and input controls. The article further uses regression analysis to test the effect of those factors on AIS data quality, finding that there is a significant positive relationship between the perceived performance of the three most important factors and perceived AIS data quality outcomes.
Rethinking autism and technology
Authors: Frauenberger Christopher
Published: March 2015

In this forum we celebrate research that helps to successfully bring the benefits of computing technologies to children, older adults, people with disabilities, and other populations that are often ignored in the design of mass-marketed products. ---
Juan Pablo Hourcade, Editor
Limited-Use Atomic Snapshots with Polylogarithmic Step Complexity
Authors: Aspnes James , Attiya Hagit , Censor-Hillel Keren , Ellen Faith
Published: March 2015

This article presents a novel implementation of a snapshot object for
n
processes, with
O
(log
2
b
log
n
) step complexity for update operations and
O
(log
b
) step complexity for scan operations, where
b
is the number of updates. The algorithm uses only reads and writes.

For polynomially many updates, this is an exponential improvement on previous snapshot algorithms, which have linear step complexity. It overcomes the existing Ω(
n
) lower bound on step complexity by having the step complexity depend on the number of updates. The key to this implementation is the construction of a new object consisting of a pair of max registers that supports a scan operation.
A buffer-based approach to rate adaptation
Authors: Huang Te-Yuan , Johari Ramesh , McKeown Nick , Trunnell Matthew , Watson Mark
Published: March 2015

Existing ABR algorithms face a significant challenge in estimating future capacity: capacity can vary widely over time, a phenomenon commonly observed in commercial services. In this work, we suggest an alternative approach: rather than presuming that capacity estimation is required, it is perhaps better to begin by using only the buffer, and then ask when capacity estimation is needed. We test the viability of this approach through a series of experiments spanning millions of real users in a commercial service. We start with a simple design which directly chooses the video rate based on the current buffer occupancy. Our own investigation reveals that capacity estimation is unnecessary in steady state; however using simple capacity estimation (based on immediate past throughput) is important during the startup phase, when the buffer itself is growing from empty. This approach allows us to reduce the rebuffer rate by 10-20% compared to Netflix's then-default ABR algorithm, while delivering a similar average video rate, and a higher video rate in steady state.
SDX
Authors: Gupta Arpit , Vanbever Laurent , Shahbaz Muhammad , Donovan Sean P. , Schlinker Brandon , Feamster Nick , Rexford Jennifer , Shenker Scott , Clark Russ , Katz-Bassett Ethan
Published: March 2015

BGP severely constrains how networks can deliver traffic over the Internet. Today's networks can only forward traffic based on the destination IP prefix, by selecting among routes offered by their immediate neighbors. We believe Software Defined Networking (SDN) could revolutionize wide-area traffic delivery, by offering direct control over packet-processing rules that match on multiple header fields and perform a variety of actions. Internet exchange points (IXPs) are a compelling place to start, given their central role in interconnecting many networks and their growing importance in bringing popular content closer to end users.

To realize a Software Defined IXP (an "SDX"), we must create compelling applications, such as "application-specific peering"---where two networks peer only for (say) streaming video traffic. We also need new programming abstractions that allow participating networks to create and run these applications and a runtime that both behaves correctly when interacting with BGP and ensures that applications do not interfere with each other. Finally, we must ensure that the system scales, both in rule-table size and computational overhead. In this paper, we tackle these challenges and demonstrate the flexibility and scalability of our solutions through controlled and in-the-wild experiments. Our experiments demonstrate that our SDX implementation can implement representative policies for hundreds of participants who advertise full routing tables while achieving sub-second convergence in response to configuration changes and routing updates.
Geosphere
Authors: Nikitopoulos Konstantinos , Zhou Juan , Congdon Ben , Jamieson Kyle
Published: March 2015

This paper presents the design and implementation of Geosphere, a physical- and link-layer design for access point-based MIMO wireless networks that consistently improves network throughput. To send multiple streams of data in a MIMO system, prior designs rely on a technique called zero-forcing, a way of "nulling" the interference between data streams by mathematically inverting the wireless channel matrix. In general, zero-forcing is highly effective, significantly improving throughput. But in certain physical situations, the MIMO channel matrix can become "poorly conditioned," harming performance. With these situations in mind, Geosphere uses sphere decoding, a more computationally demanding technique that can achieve higher throughput in such channels. To overcome the sphere decoder's computational complexity when sending dense wireless constellations at a high rate, Geosphere introduces search and pruning techniques that incorporate novel geometric reasoning about the wireless constellation. These techniques reduce computational complexity of 256-QAM systems by almost one order of magnitude, bringing computational demands in line with current 16- and 64-QAM systems already realized in ASIC. Geosphere thus makes the sphere decoder practical for the first time in a 4 × 4 MIMO, 256-QAM system. Results from our WARP testbed show that Geosphere achieves throughput gains over multi-user MIMO of 2× in 4 × 4 systems and 47% in 2 × 2 MIMO systems.
Balancing accountability and privacy in the network
Authors: Naylor David , Mukerjee Matthew K. , Steenkiste Peter
Published: March 2015

Though most would agree that accountability and privacy are both valuable, today's Internet provides little support for either. Previous efforts have explored ways to offer stronger guarantees for one of the two, typically at the expense of the other; indeed, at first glance accountability and privacy appear mutually exclusive. At the center of the tussle is the source address: in an accountable Internet, source addresses undeniably link packets and senders so hosts can be punished for bad behavior. In a privacy-preserving Internet, source addresses are hidden as much as possible.

In this paper, we argue that a balance is possible. We introduce the Accountable and Private Internet Protocol (APIP), which splits source addresses into two separate fields --- an accountability address and a return address --- and introduces independent mechanisms for managing each. Accountability addresses, rather than pointing to hosts, point to accountability delegates, which agree to vouch for packets on their clients' behalves, taking appropriate action when misbehavior is reported. With accountability handled by delegates, senders are now free to mask their return addresses; we discuss a few techniques for doing so.
Dynamic scheduling of network updates
Authors: Jin Xin , Liu Hongqiang Harry , Gandhi Rohan , Kandula Srikanth , Mahajan Ratul , Zhang Ming , Rexford Jennifer , Wattenhofer Roger
Published: March 2015

We present Dionysus, a system for fast, consistent network updates in software-defined networks. Dionysus encodes as a graph the consistency-related dependencies among updates at individual switches, and it then dynamically schedules these updates based on runtime differences in the update speeds of different switches. This dynamic scheduling is the key to its speed; prior update methods are slow because they pre-determine a schedule, which does not adapt to runtime conditions. Testbed experiments and data-driven simulations show that Dionysus improves the median update speed by 53--88% in both wide area and data center networks compared to prior methods.
Network stack specialization for performance
Authors: Marinos Ilias , Watson Robert N.M. , Handley Mark
Published: March 2015

Contemporary network stacks are masterpieces of generality, supporting many edge-node and middle-node functions. Generality comes at a high performance cost: current APIs, memory models, and implementations drastically limit the effectiveness of increasingly powerful hardware. Generality has historically been required so that individual systems could perform many functions. However, as providers have scaled services to support millions of users, they have transitioned toward thousands (or millions) of dedicated servers, each performing a few functions. We argue that the overhead of generality is now a key obstacle to effective scaling, making specialization not only viable, but necessary.

We present Sandstorm and Namestorm, web and DNS servers that utilize a clean-slate userspace network stack that exploits knowledge of application-specific workloads. Based on the netmap framework, our novel approach merges application and network-stack memory models, aggressively amortizes protocol-layer costs based on application-layer knowledge, couples tightly with the NIC event model, and exploits microarchitectural features. Simultaneously, the servers retain use of conventional programming frameworks. We compare our approach with the FreeBSD and Linux stacks using the nginx web server and NSD name server, demonstrating 2--10x and 9x improvements in web-server and DNS throughput, lower CPU usage, linear multicore scaling, and saturated NIC hardware.
Efficient coflow scheduling with Varys
Authors: Chowdhury Mosharaf , Zhong Yuan , Stoica Ion
Published: March 2015

Communication in data-parallel applications often involves a collection of parallel flows. Traditional techniques to optimize flow-level metrics do not perform well in optimizing such collections, because the network is largely agnostic to application-level requirements. The recently proposed coflow abstraction bridges this gap and creates new opportunities for network scheduling. In this paper, we address inter-coflow scheduling for two different objectives: decreasing communication time of data-intensive jobs and guaranteeing predictable communication time. We introduce the concurrent open shop scheduling with coupled resources problem, analyze its complexity, and propose effective heuristics to optimize either objective. We present Varys, a system that enables data-intensive frameworks to use coflows and the proposed algorithms while maintaining high network utilization and guaranteeing starvation freedom. EC2 deployments and trace-driven simulations show that communication stages complete up to 3.16X faster on average and up to 2X more coflows meet their deadlines using Varys in comparison to per-flow mechanisms. Moreover, Varys outperforms non-preemptive coflow schedulers by more than 5X.
LTE radio analytics made easy and accessible
Authors: Kumar Swarun , Hamed Ezzeldin , Katabi Dina , Erran Li Li
Published: March 2015

Despite the rapid growth of next-generation cellular networks, researchers and end-users today have limited visibility into the performance and problems of these networks. As LTE deployments move towards femto and pico cells, even operators struggle to fully understand the propagation and interference patterns affecting their service, particularly indoors. This paper introduces LTEye, the first open platform to monitor and analyze LTE radio performance at a fine temporal and spatial granularity. LTEye accesses the LTE PHY layer without requiring private user information or provider support. It provides deep insights into the PHY-layer protocols deployed in these networks. LTEye's analytics enable researchers and policy makers to uncover serious deficiencies in these networks due to inefficient spectrum utilization and inter-cell interference. In addition, LTEye extends synthetic aperture radar (SAR), widely used for radar and backscatter signals, to operate over cellular signals. This enables businesses and end-users to localize mobile users and capture the distribution of LTE performance across spatial locations in their facility. As a result, they can diagnose problems and better plan deployment of repeaters or femto cells. We implement LTEye on USRP software radios, and present empirical insights and analytics from multiple AT&T and Verizon base stations in our locality.
A middlebox-cooperative TCP for a non end-to-end internet
Authors: Craven Ryan , Beverly Robert , Allman Mark
Published: March 2015

Understanding, measuring, and debugging IP networks, particularly across administrative domains, is challenging. One particularly daunting aspect of the challenge is the presence of transparent middleboxes---which are now common in today's Internet. In-path middleboxes that modify packet headers are typically transparent to a TCP, yet can impact end-to-end performance or cause blackholes. We develop TCP HICCUPS to reveal packet header manipulation to both endpoints of a TCP connection. HICCUPS permits endpoints to cooperate with currently opaque middleboxes without prior knowledge of their behavior. For example, with visibility into end-to-end behavior, a TCP can selectively enable or disable performance enhancing options. This cooperation enables protocol innovation by allowing new IP or TCP functionality (e.g., ECN, SACK, Multipath TCP, Tcpcrypt) to be deployed without fear of such functionality being misconstrued, modified, or blocked along a path. HICCUPS is incrementally deployable and introduces no new options. We implement and deploy TCP HICCUPS across thousands of disparate Internet paths, highlighting the breadth and scope of subtle and hard to detect middlebox behaviors encountered. We then show how path diagnostic capabilities provided by HICCUPS can benefit applications and the network.
Application-driven bandwidth guarantees in datacenters
Authors: Lee Jeongkeun , Turner Yoshio , Lee Myungjin , Popa Lucian , Banerjee Sujata , Kang Joon-Myung , Sharma Puneet
Published: March 2015

Providing bandwidth guarantees to specific applications is becoming increasingly important as applications compete for shared cloud network resources. We present CloudMirror, a solution that provides bandwidth guarantees to cloud applications based on a new network abstraction and workload placement algorithm. An effective network abstraction should enable applications to easily and accurately specify their requirements, while simultaneously enabling the infrastructure to provision resources efficiently for deployed applications. Prior research has approached the bandwidth guarantee specification by using abstractions that resemble physical network topologies. We present a contrasting approach of deriving a network abstraction based on application communication structure, called Tenant Application Graph or TAG. CloudMirror also incorporates a new workload placement algorithm that efficiently meets bandwidth requirements specified by TAGs while factoring in high availability considerations. Extensive simulations using real application traces and datacenter topologies show that CloudMirror can handle 40% more bandwidth demand than the state of the art (e.g., the Oktopus system), while improving high availability from 20% to 70%.
FireFly
Authors: Hamedazimi Navid , Qazi Zafar , Gupta Himanshu , Sekar Vyas , Das Samir R. , Longtin Jon P. , Shah Himanshu , Tanwer Ashish
Published: March 2015

Conventional static datacenter (DC) network designs offer extreme cost vs. performance tradeoffs---simple leaf-spine networks are cost-effective but oversubscribed, while "fat tree"-like solutions offer good worst-case performance but are expensive. Recent results make a promising case for augmenting an oversubscribed network with reconfigurable inter-rack wireless or optical links. Inspired by the promise of reconfigurability, this paper presents FireFly, an inter-rack network solution that pushes DC network design to the extreme on three key fronts: (1) all links are reconfigurable; (2) all links are wireless; and (3) non top-of-rack switches are eliminated altogether. This vision, if realized, can offer significant benefits in terms of increased flexibility, reduced equipment cost, and minimal cabling complexity. In order to achieve this vision, we need to look beyond traditional RF wireless solutions due to their interference footprint which limits range and data rates. Thus, we make the case for using free-space optics (FSO). We demonstrate the viability of this architecture by (a) building a proof-of-concept prototype of a steerable small form factor FSO device using commodity components and (b) developing practical heuristics to address algorithmic and system-level challenges in network design and management.
Vidyut
Authors: Yenamandra Vivek , Srinivasan Kannan
Published: March 2015

Global synchronization across time and frequency domains significantly benefits wireless communications. Multi-Cell (Network) MIMO, interference alignment solutions, opportunistic routing techniques in ad-hoc networks, OFDMA etc. all necessitate synchronization in either time or frequency domain or both. This paper presents sysname, a system that exploits the easily accessible and ubiquitous power line infrastructure to achieve synchronization in time and frequency domains across nodes distributed beyond a single-collision domain. sysname uses the power lines to transmit a reference frequency tone to which each node locks its frequency. sysname exploits the steady periodicity of delivered power signal itself to synchronize distributed nodes in time.

We validate the extent of sysname's synchronization and evaluate its effectiveness. We verify sysname's suitability for wireless applications such as OFDMA and multi-cell MIMO by validating the benefits of global synchronization in an enterprise wireless network. Our experiments show a throughput gain of 8.2x over MegaMIMO, 7x over NemoX and 2.5x over OFDMA systems.

Enterprise wireless networks are supported by an Ethernet backbone. Researchers have been exploring techniques over the backbone to enable and assist in improving the performance of the wireless networks. Recent work also showed the benefit of sharing information in the air between the nodes to enable higher performance of the network. Even sharing information as little as synchronization information has been demonstrated to open new avenues (such as MU-MIMO, Physical Network Coding, Opportunistic routing, etc.) for the wireless networks to enhance its performance. However, another medium shared by majority of the nodes in the enterprise network - the power line infrastructure - has been largely left untapped to assist the wireless network. While the power lines are noisy and have a frequency selective transmission characteristic, its uniqueness is that its range can extend beyond that over air while it is unburdened by switching and other responsibilities of the Ethernet backbone. This paper poses the following question: How best to exploit the opportunity presented by the power lines to further enhance enterprise wireless networks?

The key contributions of this paper are the following: Identify and demonstrate the feasibility of utilizing power lines as a medium to achieve synchronization (in time and frequency domains) between nodes in the network; Demonstrate the scalability of this technique by achieving synchronization between nodes beyond the transmission range of any of the individual nodes. The paper presents empirical results pertaining to the accuracy of synchronization and the benefit of the proposed synchronization method to existing distributed wireless techniques by virtue of extension across multiple collision domains.
Quartz
Authors: Liu Yunpeng James , Gao Peter Xiang , Wong Bernard , Keshav Srinivasan
Published: March 2015

Most datacenter network (DCN) designs focus on maximizing bisection bandwidth rather than minimizing server-to-server latency. We explore architectural approaches to building low-latency DCNs and introduce Quartz, a design element consisting of a full mesh of switches. Quartz can be used to replace portions of either a hierarchical network or a random network. Our analysis shows that replacing high port-count core switches with Quartz can significantly reduce switching delays, and replacing groups of top-of-rack and aggregation switches with Quartz can significantly reduce congestion-related delays from cross-traffic. We overcome the complexity of wiring a complete mesh using low-cost optical multiplexers that enable us to efficiently implement a logical mesh as a physical ring. We evaluate our performance using both simulations and a small working prototype. Our evaluation results confirm our analysis, and demonstrate that it is possible to build low-latency DCNs using inexpensive commodity elements without significant concessions to cost, scalability, or wiring complexity.
Robust full duplex radio link
Authors: Bharadia Dinesh , Joshi Kiran , Katti Sachin
Published: March 2015

This paper presents demonstration of a real-time full duplex point-to-point link, where transmission and reception occurs in the same spectrum band simultaneously between a pair of full-duplex radios. This demo first builds a full duplex radio by implementing self-interference cancellation technique on top of a traditional half duplex radio architecture. We then establish a point-to-point link using a pair of these radios that can transmit and receive OFDM packets. By changing the environmental conditions around the full-duplex radios we then demonstrate the robustness of the self-interference cancellation to adapt to the changing environment.
Ziria
Authors: Stewart Gordon , Gowda Mahanth , Mainland Geoffrey , Radunovic Bozidar , Vytiniotis Dimitrios , Patterson Doug
Published: March 2015

Software-defined radios (SDR) have the potential to bring major innovation in wireless networking design. However, their impact so far has been limited due to complex programming tools. Most of the existing tools are either too slow to achieve the full line speeds of contemporary wireless PHYs or are too complex to master. In this demo we present our novel SDR programming environment called Ziria. Ziria consists of a novel programming language and an optimizing compiler. The compiler is able to synthesize very efficient SDR code from high-level PHY descriptions written in Ziria language. To illustrate its potential, we present the design of an LTE-like PHY layer in Ziria. We run it on the Sora SDR platform and demonstrate on a test-bed that it is able to operate in real-time.
Demo
Authors: Schmidt Mark , Heimgaertner Florian , Menth Michael
Published: March 2015

This demo presents a testbed for computer networking education. It leverages hardware virtualization to accommodate 6 PCs and 2 routers on a single testbed host to reduce costs, energy consumption, space requirements, and heat emission. The testbed excels by providing dedicated physical Ethernet and USB interfaces for virtual machines so that students can interconnect them with cables and switches like in a non-virtualized testbed
Toward a biometric-aware cloud service engine for multi-screen video applications
Authors: Hu Han , Jin Yichao , Wen Yonggang , Chua Tat-Seng , Li Xuelong
Published: March 2015

The emergence of portable devices and online social networks (OSNs) has changed the traditional video consumption paradigm by simultaneously providing multi-screen video watching, social networking engagement, etc. One challenge is to design a unified solution to support ever-growing features while guarantee system performance. In this demo, we design and implement a multi-screen technology to provide multi-screen interactions over wide area network (WAN). Furthermore, we incorporate face-detection technology into our system to identify users' bio-features and employ a machine learning based traffic scheduling mechanism to improve the system performance.
RPKI vs ROVER
Authors: Malhotra Aanchal , Goldberg Sharon
Published: March 2015

BGP, the Internet's interdomain routing protocol, is highly vulnerable to routing failures that result from unintentional misconfigurations or deliberate attacks. To defend against these failures, recent years have seen the adoption of the Resource Public Key Infrastructure (RPKI), which currently authorizes 4% of the Internet's routes. The RPKI is a completely new security infrastructure (requiring new servers, caches, and the design of new protocols), a fact that has given rise to some controversy. Thus, an alternative proposal has emerged: Route Origin Verification (ROVER}, which leverages the existing reverse DNS (rDNS) and DNSSEC to secure the interdomain routing system. Both RPKI and ROVER rely on a hierarchy of authorities to provide trusted information about the routing system. Recently, however, it has been argued that the misconfigured, faulty or compromised RPKI authorities introduce new vulnerabilities in the routing system, which can take IP prefixes offline. Meanwhile, the designers of ROVER claim that it operates in a "fail-safe mode", where "[o]ne could completely unplug a router verification application at any time and Internet routing would continue to work just as it does today". There has been debate in Internet community mailing lists about the pros and cons of both approaches. This poster therefore compares the impact of ROVER failures to those of the RPKI, in a threat model that covers misconfigurations, faults or compromises of their trusted authorities.
Traffic statistics collection with FleXam
Authors: Shirali-Shahreza Sajad , Ganjali Yashar
Published: March 2015

One of the limitations of wildcard rules in Software Defined Networks, such as OpenFlow, is losing visibility. FleXam is a flexible sampling extension for OpenFlow that allows the controller to define which packets should be sampled, what parts of each packet should be selected, and where they should be sent. Here, we present an interactive demo showing how FleXam enables the controller to dynamically adjust sampling rates and change the sampling scheme to optimally keep up with a sampling budget in the context of a traffic statistics collection application.
A user behavior based cheat detection mechanism for crowdtesting
Authors: Mok Ricky K.P. , Li Weichao , Chang Rocky K.C.
Published: March 2015

Crowdtesting is increasingly popular among researchers to carry out subjective assessments of different services. Experimenters can easily assess to a huge pool of human subjects through crowdsourcing platforms. The workers are usually anonymous, and they participate in the experiments independently. Therefore, a fundamental problem threatening the integrity of these platforms is to detect various types of cheating from the workers. In this poster, we propose cheat-detection mechanism based on an analysis of the workers' mouse cursor trajectories. It provides a jQuery-based library to record browser events. We compute a set of metrics from the cursor traces to identify cheaters. We deploy our mechanism to the survey pages for our video quality assessment tasks published on Amazon Mechanical Turk. Our results show that cheaters' cursor movement is usually more direct and contains less pauses.
Towards the super fluid cloud
Authors: Manco Filipe , Martins Joao , Huici Felipe
Published: March 2015

Traditionally, the number of VMs running on a server and how quickly these can be migrated has been less than optimal mostly because of the memory and CPU requirements imposed on the system by the full-fledged OSes that the VMs run. More recently, work towards VMs based on minimalistic or specialized OSes has started pushing the envelope of how reactive or fluid the cloud can be. In this demo we will demonstrate how to concurrently execute thousands of Xen-based VMs on a single inexpensive server. We will also show instantiation and migraion of such VMs in tens of milliseconds, and transparent, wide area migration of virtualized middleboxes by combining such VMs with the multi-path TCP (MPTCP) protocol.
Tracing multipath TCP connections
Authors: Hesmans Benjamin , Bonaventure Olivier
Published: March 2015

Multipath TCP is a new extension to TCP that enables a host to transmit the packets from a given connection by using several interfaces. We propose mptcptrace, a software that enables a detailed analysis of Multipath TCP packet traces.
DOT
Authors: Roy Arup Raton , Bari Md. Faizul , Zhani Mohamed Faten , Ahmed Reaz , Boutaba Raouf
Published: March 2015

With the growing adoption of Software Defined Networking (SDN) technology, there is a compelling need for an SDN emulator that can facilitate experimenting with new SDN solutions. Unfortunately, Mininet, the de facto standard emulator for software defined networks, fails to scale with network size and traffic volume. To address these limitations, we developed Distributed OpenFlow Testbed (DOT), a highly scalable emulator for SDN. It can emulate large SDN deployments by distributing the workload over a cluster of compute nodes. Moreover, DOT can emulate a wider range of network services compared to other publicly available SDN emulators and simulators. Our demonstration will illustrate several features of DOT including: (i) how easy it is to setup the emulator, (ii) how to deploy a topology using a single configuration file, (iii) how to run a connectivity test to ensure that the emulated network is properly deployed, and (iv) how to control and monitor the emulated components from a centralized location. We will also showcase DOT by emulating two applications: (i) policy based traffic steering through middleboxes and (ii) traffic monitoring.
Rethinking buffer management in data center networks
Authors: Mushtaq Aisha , Ismail Asad Khalid , Wasay Abdul , Mahmood Bilal , Qazi Ihsan Ayyub , Uzmi Zartash Afzal
Published: March 2015

Data center operators face extreme challenges in simultaneously providing low latency for short flows, high throughput for long flows, and high burst tolerance. We propose a buffer management strategy that addresses these challenges by isolating short and long flows into separate buffers, sizing these buffers based on flow requirements, and scheduling packets to meet different flow-level objectives. Our design provides new opportunities for performance improvements that complement transport layer optimisations.
Gastroduodenal mucus bicarbonate barrier: protection against acid and pepsin
Authors: Allen Adrian , Flemström Gunnar
Published: March 2015

Secretion of bicarbonate into the adherent layer of mucus gel creates a pH gradient with a near-neutral pH at the epithelial surfaces in stomach and duodenum, providing the first line of mucosal protection against luminal acid. The continuous adherent mucus layer is also a barrier to luminal pepsin, thereby protecting the underlying mucosa from proteolytic digestion. In this article we review the present state of the gastroduodenal mucus bicarbonate barrier two decades after the first supporting experimental evidence appeared. The primary function of the adherent mucus gel layer is a structural one to create a stable, unstirred layer to support surface neutralization of acid and act as a protective physical barrier against luminal pepsin. Therefore, the emphasis on mucus in this review is on the form and role of the adherent mucus gel layer. The primary function of the mucosal bicarbonate secretion is to neutralize acid diffusing into the mucus gel layer and to be quantitatively sufficient to maintain a near-neutral pH at the mucus-mucosal surface interface. The emphasis on mucosal bicarbonate in this review is on the mechanisms and control of its secretion and the establishment of a surface pH gradient. Evidence suggests that under normal physiological conditions, the mucus bicarbonate barrier is sufficient for protection of the gastric mucosa against acid and pepsin and is even more so for the duodenum.
Acute and chronic effects of alcohol exposure on skeletal muscle c-myc, p53, and Bcl-2 mRNA expression
Authors: Nakahara Tatsuo , Hashimoto Kijiro , Hirano Makoto , Koll Michael , Martin Colin R. , Preedy Victor R.
Published: March 2015

Skeletal muscle atrophy is a common feature in alcoholism that affects up to two-thirds of alcohol misusers, and women appear to be particularly susceptible. There is also some evidence to suggest that malnutrition exacerbates the effects of alcohol on muscle. However, the mechanisms responsible for the myopathy remain elusive, and some studies suggest that acetaldehyde, rather than alcohol, is the principal pathogenic perturbant. Previous reports on rats dosed acutely with ethanol (<24 h) have suggested that increased proto-oncogene expression (i.e., c-myc) may be a causative process, possibly via activating preapoptotic or transcriptional pathways. We hypothesized that 1) increases in c-myc mRNA levels also occur in muscle exposed chronically to alcohol, 2) muscle of female rats is more sensitive than that from male rats, 3) raising acetaldehyde will also increase c-myc, 4) prior starvation will cause further increases in c-myc mRNA expression in response to ethanol, and 5) other genes involved in apoptosis (i.e., p53 and Bcl-2) would also be affected by alcohol. To test this, we measured c-myc mRNA levels in skeletal muscle of rats dosed either chronically (6–7 wk; ethanol as 35% of total dietary energy) or acutely (2.5 h; ethanol as 75 mmol/kg body wt ip) with ethanol. All experiments were carried out in male Wistar rats (∼0.1–0.15 kg body wt) except the study that examined gender susceptibility in male and female rats. At the end of the studies, rats were killed, and c-myc, p53, and Bcl-2 mRNA was analyzed in skeletal muscle by RT-PCR with an endogenous internal standard, GAPDH. The results showed that 1) in male rats fed ethanol chronically, there were no increases in c-myc mRNA; 2) increases, however, occurred in c-myc mRNA in muscle from female rats fed ethanol chronically; 3) raising endogenous acetaldehyde with cyanamide increased c-myc mRNA in acute studies; 4) starvation per se increased c-myc mRNA levels and at 1 day potentiated the acute effects of ethanol, indicative of a sensitization response; 5) the only effect seen with p53 mRNA levels was a decrease in muscle of rats starved for 1 day compared with fed rats, and there was no statistically significant effect on Bcl-2 mRNA in any of the experimental conditions. The increases in c-myc may well represent a preapoptotic effect, or even a nonspecific cellular stress response to alcohol and/or acetaldehyde. These data are important in our understanding of a common muscle pathology induced by alcohol.