OpenRaiser/Intern-Atlas huggingface dataset:
Multi-Branch Tomlinson-Harashima Precoding for MU-MIMO Systems: Theory and Algorithms
Venue: arXiv cs.IT 2014
Year: 2014

Tomlinson-Harashima precoding (THP) is a nonlinear processing technique employed at the transmit side and is a dual to the successive interference cancelation (SIC) detection at the receive side. Like SIC detection, the performance of THP strongly depends on the ordering of the precoded symbols. The optimal ordering algorithm, however, is impractical for multiuser MIMO (MU-MIMO) systems with multiple receive antennas due to the fact that the users are geographically distributed. In this paper, we propose a multi-branch THP (MB-THP) scheme and algorithms that employ multiple transmit processing and ordering strategies along with a selection scheme to mitigate interference in MU-MIMO systems. Two types of multi-branch THP (MB-THP) structures are proposed. The first one employs a decentralized strategy with diagonal weighted filters at the receivers of the users and the second uses a diagonal weighted filter at the transmitter. The MB-MMSE-THP algorithms are also derived based on an extended system model with the aid of an LQ decomposition, which is much simpler compared to the conventional MMSE-THP algorithms. Simulation results show that a better bit error rate (BER) performance can be achieved by the proposed MB-MMSE-THP precoder with a small computational complexity increase.
Common Information based Markov Perfect Equilibria for Linear-Gaussian Games with Asymmetric Information
Venue: arXiv cs.SY 2014
Year: 2014

We consider a class of two-player dynamic stochastic nonzero-sum games where the state transition and observation equations are linear, and the primitive random variables are Gaussian. Each controller acquires possibly different dynamic information about the state process and the other controller's past actions and observations. This leads to a dynamic game of asymmetric information among the controllers. Building on our earlier work on finite games with asymmetric information, we devise an algorithm to compute a Nash equilibrium by using the common information among the controllers. We call such equilibria common information based Markov perfect equilibria of the game, which can be viewed as a refinement of Nash equilibrium in games with asymmetric information. If the players' cost functions are quadratic, then we show that under certain conditions a unique common information based Markov perfect equilibrium exists. Furthermore, this equilibrium can be computed by solving a sequence of linear equations. We also show through an example that there could be other Nash equilibria in a game of asymmetric information, not corresponding to common information based Markov perfect equilibria.
Process Evolution Supported by Rationale: An Empirical Investigation of Process Changes
Venue: arXiv cs.SE 2014
Year: 2014

Evolving a software process model without a retrospective and, in consequence, without an understanding of the process evolution, can lead to severe problems for the software development organization, e.g., inefficient performance as a consequence of the arbitrary introduction of changes or difficulty in demonstrating compliance to a given standard. Capturing information on the rationale behind changes can provide a means for better understanding process evolution. This article presents the results of an exploratory study with the goal of understanding the nature of process changes in a given context. It presents the most important issues that motivated process engineers changing important aerospace software process standards during an industrial project. The study is part of research work intended to incrementally define a systematic mechanism for process evolution supported by rationale information.
On the Computing Power of $+$, $-$, and $\times$
Venue: arXiv cs.CC 2014
Year: 2014

Modify the Blum-Shub-Smale model of computation replacing the permitted computational primitives (the real field operations) with any finite set $B$ of real functions semialgebraic over the rationals. Consider the class of boolean decision problems that can be solved in polynomial time in the new model by machines with no machine constants. How does this class depend on $B$? We prove that it is always contained in the class obtained for $B = \{+, -, \times\}$. Moreover, if $B$ is a set of continuous semialgebraic functions containing $+$ and $-$, and such that arbitrarily small numbers can be computed using $B$, then we have the following dichotomy: either our class is $\mathsf P$ or it coincides with the class obtained for $B = \{+, -, \times\}$.
Performance Analysis of a Network of Event-based Systems
Venue: arXiv cs.SY 2014
Year: 2014

We consider a scenario where multiple event-based systems use a wireless network to communicate with their respective controllers. These systems use a contention resolution mechanism (CRM) to arbitrate access to the network. We present a Markov model for the network interactions between the event-based systems. Using this model, we obtain an analytical expression for the reliability, or the probability of successfully transmitting a packet, in this network. There are two important aspects to our model. Firstly, our model captures the joint interactions of the event-triggering policy and the CRM. This is required because event-triggering policies typically adapt to the CRM outcome. Secondly, the model is obtained by decoupling interactions between the different systems in the network, drawing inspiration from Bianchi's analysis of IEEE 802.11. This is required because the network interactions introduce a correlation between the system variables. We present Monte-Carlo simulations that validate our model under various network configurations, and verify our performance analysis as well.
A Scalable Conditional Independence Test for Nonlinear, Non-Gaussian Data
Venue: arXiv cs.AI 2014
Year: 2014

Many relations of scientific interest are nonlinear, and even in linear systems distributions are often non-Gaussian, for example in fMRI BOLD data. A class of search procedures for causal relations in high dimensional data relies on sample derived conditional independence decisions. The most common applications rely on Gaussian tests that can be systematically erroneous in nonlinear non-Gaussian cases. Recent work (Gretton et al. (2009), Tillman et al. (2009), Zhang et al. (2011)) has proposed conditional independence tests using Reproducing Kernel Hilbert Spaces (RKHS). Among these, perhaps the most efficient has been KCI (Kernel Conditional Independence, Zhang et al. (2011)), with computational requirements that grow effectively at least as O(N3), placing it out of range of large sample size analysis, and restricting its applicability to high dimensional data sets. We propose a class of O(N2) tests using conditional correlation independence (CCI) that require a few seconds on a standard workstation for tests that require tens of minutes to hours for the KCI method, depending on degree of parallelization, with similar accuracy. For accuracy on difficult nonlinear, non-Gaussian data sets, we also compare a recent test due to Harris & Drton (2012), applicable to nonlinear, non-Gaussian distributions in the Gaussian copula, as well as to partial correlation, a linear Gaussian test.
Experimental Design for Human-in-the-Loop Driving Simulations
Venue: arXiv cs.SY 2014
Year: 2014

This report describes a new experimental setup for human-in-the-loop simulations. A force feedback simulator with four axis motion has been setup for real-time driving experiments. The simulator will move to simulate the forces a driver feels while driving, which allows for a realistic experience for the driver. This setup allows for flexibility and control for the researcher in a realistic simulation environment. Experiments concerning driver distraction can also be carried out safely in this test bed, in addition to multi-agent experiments. All necessary code to run the simulator, the additional sensors, and the basic processing is available for use.
Improving Third-Party Relaying for LTE-A: A Realistic Simulation Approach
Venue: arXiv cs.NI 2014
Year: 2014

In this article we propose solutions to diverse conflicts that result from the deployment of the (still immature) relay node (RN) technology in LTE-A networks. These conflicts and their possible solutions have been observed by implementing standard-compliant relay functionalities on the Vienna simulator. As an original experimental approach, we model realistic RN operation, taking into account that transmitters are not active all the time due to half-duplex RN operation. We have rearranged existing elements in the simulator in a manner that emulates RN behavior, rather than implementing a standalone brand-new component for the simulator. We also study analytically some of the issues observed in the interaction between the network and the RNs, to draw conclusions beyond simulation observation. The main observations of this paper are that: $i$) Additional time-varying interference management steps are needed, because the LTE-A standard employs a fixed time division between eNB-RN and RN-UE transmissions (typical relay capacity or throughput research models balance them optimally, which is unrealistic nowadays); $ii$) There is a trade-off between the time-division constraints of relaying and multi-user diversity; the stricter the constraints on relay scheduling are, the less flexibility schedulers have to exploit channel variation; and $iii$) Thee standard contains a variety of parameters for relaying configuration, but not all cases of interest are covered.
Retracing some paths in Process Algebra
Venue: arXiv cs.LO 2014
Year: 2014

We use traced monoidal categories to give a precise general version of "geometry of interaction". We give a number of examples of both "particle-style" and "wave-style" instances of this construction. We relate these ideas to semantics of computation.
Streaming Video over HTTP with Consistent Quality
Venue: arXiv cs.NI 2014
Year: 2014

In conventional HTTP-based adaptive streaming (HAS), a video source is encoded at multiple levels of constant bitrate representations, and a client makes its representation selections according to the measured network bandwidth. While greatly simplifying adaptation to the varying network conditions, this strategy is not the best for optimizing the video quality experienced by end users. Quality fluctuation can be reduced if the natural variability of video content is taken into consideration. In this work, we study the design of a client rate adaptation algorithm to yield consistent video quality. We assume that clients have visibility into incoming video within a finite horizon. We also take advantage of the client-side video buffer, by using it as a breathing room for not only network bandwidth variability, but also video bitrate variability. The challenge, however, lies in how to balance these two variabilities to yield consistent video quality without risking a buffer underrun. We propose an optimization solution that uses an online algorithm to adapt the video bitrate step-by-step, while applying dynamic programming at each step. We incorporate our solution into PANDA -- a practical rate adaptation algorithm designed for HAS deployment at scale.
Goal-Oriented Setup and Usage of Custom-Tailored Software Cockpits
Venue: arXiv cs.SE 2014
Year: 2014

Software Cockpits, also known as Software Project Control Centers, support the management and controlling of software and system development projects and provide means for quantitative measurement-based project control. Currently, many companies are developing simple control dashboards that are mainly based on Spreadsheet applications. Alternatively, they use solutions providing a fixed set of project control functionality that cannot be sufficiently customized to their specific needs and goals. Specula is a systematic approach for defining reusable, customizable control components and instantiate them according to different organizational goals and characteristics based on the Quality Improvement Paradigm (QIP) and GQM. This article gives an overview of the Specula approach, including the basic conceptual model, goal-oriented measurement, and the composition of control components based on explicitly stated measurement goals. Related approaches are discussed and the use of Specula as part of industrial case studies is described.
On the third weight of generalized Reed-Muller codes
Venue: arXiv cs.IT 2014
Year: 2014

In this paper, we study the third weight of generalized Reed-Muller codes. We prove under some restrictive condition that the third weight of generalized Reed-Muller codes depends on the third weight of generalized Reed-Muller codes of small order with two variables. In some cases, we are able to determine the third weight and the third weight codewords of generalized Reed-Muller codes.
Service Oriented Paradigm for Massive Multiplayer Online Games
Venue: arXiv cs.NI 2014
Year: 2014

In recent times Massive Multiplayer Online Game has appeared as a computer game that enables hundreds of players from all parts of the world to interact in a game world (common platform) at the same time instance. Current architecture used for MMOGs based on the classic tightly coupled distributed system. While, MMOGs are getting more interactive same time number of interacting users is increasing, classic implementation architecture may raise scalability and interdependence issues. This requires a loosely coupled service oriented architecture to support evolution in MMOG application. Data flow architecture, Event driven architecture and client server architecture are basic date orchestration approaches used by any service oriented architecture. Real time service is hottest issue for service oriented architecture. The basic requirement of any real time service oriented architecture is to ensure the quality of service. In this paper we have proposed a service oriented architecture for massive multiplayer online game and a specific middleware (based on open source DDS) in MMOGs for fulfilling real time constraints.
k-Colorability is Graph Automaton Recognizable
Venue: arXiv cs.FL 2014
Year: 2014

Automata operating on general graphs have been introduced by virtue of graphoids. In this paper we construct a graph automaton that recognizes $k$-colorable graphs.
Graphical Interface for Visually Impaired People Based on Bi-stable Solenoids
Venue: arXiv cs.HC 2014
Year: 2014

In this paper a concept for hardware realization of graphic tactile display for visually impaired peoples is presented. For realization of tactile actuators bi-stable, solenoids and PIC based control board are used. The selected algorithm for series activation of each row of display allows using minimal number of active components to set and reset the solenoids. Finally, a program algorithm of control board is discussed. The project is funded by Bulgarian National Science Fund NSF Grant D ID 02 14, 2009 2013
Ranking Templates for Linear Loops
Venue: arXiv cs.LO 2014
Year: 2014

We present a new method for the constraint-based synthesis of termination arguments for linear loop programs based on linear ranking templates. Linear ranking templates are parametrized, well-founded relations such that an assignment to the parameters gives rise to a ranking function. This approach generalizes existing methods and enables us to use templates for many different ranking functions with affine-linear components. We discuss templates for multiphase, piecewise, and lexicographic ranking functions. Because these ranking templates require both strict and non-strict inequalities, we use Motzkin's Transposition Theorem instead of Farkas Lemma to transform the generated $\exists\forall$-constraint into an $\exists$-constraint.
Linear Ranking for Linear Lasso Programs
Venue: arXiv cs.LO 2014
Year: 2014

The general setting of this work is the constraint-based synthesis of termination arguments. We consider a restricted class of programs called lasso programs. The termination argument for a lasso program is a pair of a ranking function and an invariant. We present the---to the best of our knowledge---first method to synthesize termination arguments for lasso programs that uses linear arithmetic. We prove a completeness theorem. The completeness theorem establishes that, even though we use only linear (as opposed to non-linear) constraint solving, we are able to compute termination arguments in several interesting cases. The key to our method lies in a constraint transformation that replaces a disjunction by a sum.
Continuous Speech Recognition Based on Deterministic Finite Automata Machine using Utterance and Pitch Verification
Venue: arXiv cs.FL 2014
Year: 2014

This paper introduces a set of acoustic modeling techniques for utterance verification (UV) based continuous speech recognition (CSR). Utterance verification in this work implies the ability to determine when portions of a hypothesized word string correspond to incorrectly decoded vocabulary words or out-of-vocabulary words that may appear in an utterance. This capability is implemented here as a likelihood ratio (LR). There are two UV techniques that are presented here. The first is voice verification along with the vocabulary testing, at the same time the parameters for UV models are generated based on the optimization criterion which is directly related to the LR measure. The second technique is a pitch recognition based on weighted finite-state transducers. These transducers provide a common and natural representation for major components of speech recognition systems, including hidden Markov models (HMMs), context-dependency models, pronunciation dictionaries, statistical grammars, and word or phone lattices. The finite state machine processes the acoustic parameters of UV models. The results of an experimental study presented in the paper shows that LR based parameter estimation results in a significant improvement in UV performance for this task. The study also found that the use of the LR based weighted finite-state transducers along with the UV, can provide as much as an 11% improvement in UV performance when compared to existing UV procedures. Finally, it was also found that the performance of the finite state machine was highly dependent on the use of the LR criterion in training acoustic models. Several observations are made in the paper concerning the formation of confidence measures for UV and the interaction of these techniques with statistical language models.
BDGS: A Scalable Big Data Generator Suite in Big Data Benchmarking
Venue: arXiv cs.DB 2014
Year: 2014

Data generation is a key issue in big data benchmarking that aims to generate application-specific data sets to meet the 4V requirements of big data. Specifically, big data generators need to generate scalable data (Volume) of different types (Variety) under controllable generation rates (Velocity) while keeping the important characteristics of raw data (Veracity). This gives rise to various new challenges about how we design generators efficiently and successfully. To date, most existing techniques can only generate limited types of data and support specific big data systems such as Hadoop. Hence we develop a tool, called Big Data Generator Suite (BDGS), to efficiently generate scalable big data while employing data models derived from real data to preserve data veracity. The effectiveness of BDGS is demonstrated by developing six data generators covering three representative data types (structured, semi-structured and unstructured) and three data sources (text, graph, and table data).
Distributed and Centralized Hybrid CSMA/CA-TDMA Schemes for Single-Hop Wireless Networks
Venue: arXiv cs.NI 2014
Year: 2014

The strength of carrier-sense multiple access with collision avoidance (CSMA/CA) can be combined with that of time-division multiple access (TDMA) to enhance the channel access performance in wireless networks such as the IEEE 802.15.4-based wireless personal area networks (WPANs). In particular, the performance of legacy CSMA/CA-based medium access control (MAC) scheme in congested networks can be enhanced through a hybrid CSMA/CA-TDMA scheme while preserving the scalability property. In this paper, we present distributed and centralized channel access models which follow the transmission strategies based on Markov decision process (MDP) to access both contention period and contention-free period in an intelligent way. The models consider the buffer status as an indication of congestion provided that the offered traffic does not exceed the channel capacity. We extend the models to consider the hidden node collision problem encountered due to the signal attenuation caused by channel fading. The simulation results show that the MDP-based distributed channel access scheme outperforms the legacy slotted CSMA/CA scheme. This scheme also works efficiently in a network consisting of heterogeneous nodes. The centralized model outperforms the distributed model but requires the global information of the network.
GreenMail: Reducing Email Service's Carbon Emission with Minimum Cost
Venue: arXiv cs.OH 2014
Year: 2014

Internet services contribute a large fraction of worldwide carbon emission nowadays, in a context of increasing number of companies tending to provide and more and more developers use Internet services. Noticeably, a trend is those service providers are trying to reduce their carbon emissions by utilizing on-site or off-site renewable energy in their datacenters in order to attract more customers. With such efforts have been paid, there are still some users who are aggressively calling for even cleaner Internet services. For example, over 500,000 Facebook users petitioned the social networking site to use renewable energy to power its datacenter. However, it seems impossible for such demand to be satisfied merely from the inside of those production datacenters, considering the transition cost and stability. Outside the existing Internet services, on the other hand, may easily set up a proxy service to attract those renewable-energy-sensitive users, by 1) using carbon neutral or even over-offsetting cloud instances to bridge the end user and traditional Internet services; and 2) estimating and offsetting the carbon emissions from the traditional Internet services. In our paper, we proposed GreenMail, which is a general IMAP proxy caching system that connects email users and traditional email services. GreenMail runs on green web hosts to cache users' emails on green cloud instances. Besides, it offsets the carbon emitted by traditional backend email services. With GreenMail, users could set a carbon emission constraint and use traditional email service without breaking any code modification of user side and email server side.