Tohoku University

Displaying 1-14 of 14 results

  • White Papers // Jan 2012

    Marker-Directed Optimization of UnCAL Graph Transformations

    Buneman et al. proposed a graph algebra called UnCAL (Un-structured CALculus) for compositional graph transformations based on structural recursion, and the authors have recently applied to model transformations. The compositional nature of the algebra greatly enhances the modularity of transformations. However, intermediate results generated between composed transformations cause overhead. Buneman...

    Provided By Tohoku University

  • White Papers // Jul 2011

    Multi-User Joint Tx/Iterative Rx MMSE-FDE and Successive MUI Cancellation for Uplink DS-CDMA

    Uplink multi-user Direct Sequence-Code Division Multi-Access (DS-CDMA) suffers from strong Multi-User Interference (MUI) and self Inter-Chip Interference (ICI) caused by severe frequency-selective fading. In this paper, the authors propose a joint Tx/iterative Rx Frequency-Domain Equalization (FDE) based on Minimum Mean Square Error (MMSE) criterion and successive MUI Cancellation (MUIC) for...

    Provided By Tohoku University

  • White Papers // Feb 2011

    Secure Multiplex Network Coding

    Network coding attracts much attention recently because it can offer improvements in some metrics, such as throughput and energy consumption. On the other hand, the information theoretic security also attracts much attention because it offers security that does not depend on a conjectured difficulty of some computational problem. A juncture...

    Provided By Tohoku University

  • White Papers // Feb 2011

    Iterative MMSE Detection and Interference Cancellation for Uplink SC-FDMA MIMO Using HARQ

    For high-speed packet access, Hybrid Automatic Repeat reQuest (HARQ) and Multiple-Input Multiple-Output (MIMO) multiplexing are indispensable techniques. As the multiple-access technique, Single Carrier (SC)-Frequency-Division Multiple-Access (FDMA) using transmit filtering is promising. The use of square-root Nyquist transmit filter reduces Peak-to-Average Power Ratio (PAPR) of the transmit SC-FDMA signal and increases...

    Provided By Tohoku University

  • White Papers // Feb 2011

    Training Sequence-Aided QRM-MLD Block Signal Detection for Single-Carrier MIMO Spatial Multiplexing

    The authors propose a Maximum Likelihood Block signal Detection using QR decomposition and M-algorithm (called QRMMLBD) for Training sequence-Aided Single-Carrier (TA-SC) Multi-Input Multi-Output (MIMO) spatial multiplexing. QRM-MLBD can significantly improve the Packet Error Rate (PER) performance of Cyclic Prefix-inserted Single-Carrier (CP-SC) MIMO spatial multiplexing when compared to the frequency-domain Minimum...

    Provided By Tohoku University

  • White Papers // Feb 2011

    HARQ Throughput Enhancement Using Maximum Likelihood Block Detection With Recursive QR Packet Combining and M-Algorithm for Single-Carrier MIMO

    For achieving very high-speed and high quality packet transmission, the joint use of Multi-Input Multi-Output (MIMO) spatial multiplexing and Hybrid Automatic Repeat reQuest (HARQ) is very effective. The HARQ throughput depends on the packet combining scheme. In this paper, the authors consider a Single-Carrier (SC) MIMO and propose a maximum...

    Provided By Tohoku University

  • White Papers // Nov 2010

    Econometric Analysis Of Fiscal Policy Budget Constraints In Endogenous Growth Models

    Kneller et al. (1999) examined the predictions of the public-policy endogenous growth models of Barro (1990) and others that suggest that unlike distortionary taxation and productive expenditures, nondistortionary taxation and nonproductive expenditures have no direct effect on the rate of growth. This paper provides an econometric theory with their empirical...

    Provided By Tohoku University

  • White Papers // Sep 2010

    Exponential Decreasing Rate of Leaked Information in Universal Random Privacy Amplification

    The study of secure communication in the presence of an eavesdropper began with Wyner. Following Wyner, Csiszar & Korner dealt with this topic. In this study, the authors consider a sender Alice, an authorized receiver Bob and an unauthorized receiver Eve, who is referred to as a wire-tapper. This research...

    Provided By Tohoku University

  • White Papers // Jul 2010

    On Bounding Problems of Quantitative Information Flow

    Researchers have proposed formal definitions of quantitative information flow based on information theoretic notions such as the Shannon entropy, the min entropy, the guessing entropy, and channel capacity. This paper investigates the hardness of precisely checking the quantitative information flow of a program according to such definitions. More precisely, the...

    Provided By Tohoku University

  • White Papers // May 2010

    A Type System for Observational Determinism

    Zdancewic and Myers introduced observational determinism as a scheduler independent notion of security for concurrent programs. This paper proposes a type system for verifying observational determinism. The authors' type system verifies observational determinism by itself, and does not require the type checked program to be confluent. A polynomial time type...

    Provided By Tohoku University

  • White Papers // May 2010

    Quantitative Information Flow - Verification Hardness and Possibilities

    Researchers have proposed formal definitions of quantitative information flow based on information theoretic notions such as the Shannon entropy, the min entropy, the guessing entropy, and channel capacity. This paper investigates the hardness and possibilities of precisely checking and inferring quantitative information flow according to such definitions. The authors prove...

    Provided By Tohoku University

  • White Papers // Jan 2010

    Network Application Identification Based on Communication Characteristics of Application Messages

    A person-to-person information sharing is easily realized by P2P networks in which servers are not essential. Leakage of information, which are caused by malicious accesses for P2P networks, has become a new social issues. To prevent information leakage, it is necessary to detect and block traffics of P2P software. Since...

    Provided By Tohoku University

  • White Papers // Aug 2009

    Fractional Ownerships for Safe Memory Deallocation

    The authors propose a type system for a programming language with memory allocation/de-allocation primitives, which prevents memory-related errors such as double-frees and memory leaks. The main idea is to augment pointer types with fractional ownerships, which express both capabilities and obligations to access or de-allocate memory cells. By assigning an...

    Provided By Tohoku University

  • White Papers // May 2009

    Energy Saving in Wireless Sensor Networks

    With the development of low-cost processor, memory, and radio technologies, it becomes possible to build inexpensive wireless micro-sensor nodes. However, energy is the biggest constraint to wireless sensor capabilities and such constraint combined with a typical deployment of large numbers of sensor nodes have posed many challenges to the design...

    Provided By Tohoku University

  • White Papers // May 2009

    Energy Saving in Wireless Sensor Networks

    With the development of low-cost processor, memory, and radio technologies, it becomes possible to build inexpensive wireless micro-sensor nodes. However, energy is the biggest constraint to wireless sensor capabilities and such constraint combined with a typical deployment of large numbers of sensor nodes have posed many challenges to the design...

    Provided By Tohoku University

  • White Papers // Feb 2011

    Secure Multiplex Network Coding

    Network coding attracts much attention recently because it can offer improvements in some metrics, such as throughput and energy consumption. On the other hand, the information theoretic security also attracts much attention because it offers security that does not depend on a conjectured difficulty of some computational problem. A juncture...

    Provided By Tohoku University

  • White Papers // Sep 2010

    Exponential Decreasing Rate of Leaked Information in Universal Random Privacy Amplification

    The study of secure communication in the presence of an eavesdropper began with Wyner. Following Wyner, Csiszar & Korner dealt with this topic. In this study, the authors consider a sender Alice, an authorized receiver Bob and an unauthorized receiver Eve, who is referred to as a wire-tapper. This research...

    Provided By Tohoku University

  • White Papers // Jan 2010

    Network Application Identification Based on Communication Characteristics of Application Messages

    A person-to-person information sharing is easily realized by P2P networks in which servers are not essential. Leakage of information, which are caused by malicious accesses for P2P networks, has become a new social issues. To prevent information leakage, it is necessary to detect and block traffics of P2P software. Since...

    Provided By Tohoku University

  • White Papers // May 2010

    Quantitative Information Flow - Verification Hardness and Possibilities

    Researchers have proposed formal definitions of quantitative information flow based on information theoretic notions such as the Shannon entropy, the min entropy, the guessing entropy, and channel capacity. This paper investigates the hardness and possibilities of precisely checking and inferring quantitative information flow according to such definitions. The authors prove...

    Provided By Tohoku University

  • White Papers // Jul 2010

    On Bounding Problems of Quantitative Information Flow

    Researchers have proposed formal definitions of quantitative information flow based on information theoretic notions such as the Shannon entropy, the min entropy, the guessing entropy, and channel capacity. This paper investigates the hardness of precisely checking the quantitative information flow of a program according to such definitions. More precisely, the...

    Provided By Tohoku University

  • White Papers // Nov 2010

    Econometric Analysis Of Fiscal Policy Budget Constraints In Endogenous Growth Models

    Kneller et al. (1999) examined the predictions of the public-policy endogenous growth models of Barro (1990) and others that suggest that unlike distortionary taxation and productive expenditures, nondistortionary taxation and nonproductive expenditures have no direct effect on the rate of growth. This paper provides an econometric theory with their empirical...

    Provided By Tohoku University

  • White Papers // Feb 2011

    HARQ Throughput Enhancement Using Maximum Likelihood Block Detection With Recursive QR Packet Combining and M-Algorithm for Single-Carrier MIMO

    For achieving very high-speed and high quality packet transmission, the joint use of Multi-Input Multi-Output (MIMO) spatial multiplexing and Hybrid Automatic Repeat reQuest (HARQ) is very effective. The HARQ throughput depends on the packet combining scheme. In this paper, the authors consider a Single-Carrier (SC) MIMO and propose a maximum...

    Provided By Tohoku University

  • White Papers // Jul 2011

    Multi-User Joint Tx/Iterative Rx MMSE-FDE and Successive MUI Cancellation for Uplink DS-CDMA

    Uplink multi-user Direct Sequence-Code Division Multi-Access (DS-CDMA) suffers from strong Multi-User Interference (MUI) and self Inter-Chip Interference (ICI) caused by severe frequency-selective fading. In this paper, the authors propose a joint Tx/iterative Rx Frequency-Domain Equalization (FDE) based on Minimum Mean Square Error (MMSE) criterion and successive MUI Cancellation (MUIC) for...

    Provided By Tohoku University

  • White Papers // Feb 2011

    Iterative MMSE Detection and Interference Cancellation for Uplink SC-FDMA MIMO Using HARQ

    For high-speed packet access, Hybrid Automatic Repeat reQuest (HARQ) and Multiple-Input Multiple-Output (MIMO) multiplexing are indispensable techniques. As the multiple-access technique, Single Carrier (SC)-Frequency-Division Multiple-Access (FDMA) using transmit filtering is promising. The use of square-root Nyquist transmit filter reduces Peak-to-Average Power Ratio (PAPR) of the transmit SC-FDMA signal and increases...

    Provided By Tohoku University

  • White Papers // Feb 2011

    Training Sequence-Aided QRM-MLD Block Signal Detection for Single-Carrier MIMO Spatial Multiplexing

    The authors propose a Maximum Likelihood Block signal Detection using QR decomposition and M-algorithm (called QRMMLBD) for Training sequence-Aided Single-Carrier (TA-SC) Multi-Input Multi-Output (MIMO) spatial multiplexing. QRM-MLBD can significantly improve the Packet Error Rate (PER) performance of Cyclic Prefix-inserted Single-Carrier (CP-SC) MIMO spatial multiplexing when compared to the frequency-domain Minimum...

    Provided By Tohoku University

  • White Papers // May 2010

    A Type System for Observational Determinism

    Zdancewic and Myers introduced observational determinism as a scheduler independent notion of security for concurrent programs. This paper proposes a type system for verifying observational determinism. The authors' type system verifies observational determinism by itself, and does not require the type checked program to be confluent. A polynomial time type...

    Provided By Tohoku University

  • White Papers // Jan 2012

    Marker-Directed Optimization of UnCAL Graph Transformations

    Buneman et al. proposed a graph algebra called UnCAL (Un-structured CALculus) for compositional graph transformations based on structural recursion, and the authors have recently applied to model transformations. The compositional nature of the algebra greatly enhances the modularity of transformations. However, intermediate results generated between composed transformations cause overhead. Buneman...

    Provided By Tohoku University

  • White Papers // Aug 2009

    Fractional Ownerships for Safe Memory Deallocation

    The authors propose a type system for a programming language with memory allocation/de-allocation primitives, which prevents memory-related errors such as double-frees and memory leaks. The main idea is to augment pointer types with fractional ownerships, which express both capabilities and obligations to access or de-allocate memory cells. By assigning an...

    Provided By Tohoku University