We have proposed a novel call admission control (CAC) method for maximizing total user satisfaction in a heterogeneous traffic network and showed their effectiveness by using the optimal threshold from numerical analysis [1],[2]. With these CAC methods, it is assumed that only selfish users exist in a network. However, we need to consider the possibility that some cooperative users exist who would agree to reduce their requested bandwidth to improve another user's Quality of Service (QoS). Under this assumption, conventional CAC may not be optimal. If there are cooperative users in the network, we need control methods that encourage such user cooperation. However, such “encourage” control methods have not yet been proposed. Therefore, in this paper, we propose novel CAC methods for cooperative users by using queueing theory. Numerical analyses show their effectiveness. We also analyze the characteristics of the optimal control parameter of the threshold.

In anonymous reputation systems, where after an interaction between anonymous users, one of the users evaluates the peer by giving a rating. Ratings for a user are accumulated, which becomes the reputation of the user. By using the reputation, we can know the reliability of an anonymous user. Previously, anonymous reputation systems have been proposed, using an anonymous e-cash scheme. However, in the e-cash-based systems, the bank grasps the accumulated reputations for all users, and the fluctuation of reputations. These are private information for users. Furthermore, the timing attack using the deposit times is possible, which makes the anonymity weak. In this paper, we propose an anonymous reputation system, where the reputations of users are secret for even the reputation manager such as the bank. Our approach is to adopt an anonymous credential certifying the accumulated reputation of a user. Initially a user registers with the reputation manager, and is issued an initial certificate. After each interaction with a rater, the user as the ratee obtains an updated certificate certifying the previous reputation summed up by the current rating. The update protocol is based on the zero-knowledge proofs, and thus the reputations are secret for the reputation manager. On the other hand, due to the certificate, the user cannot maliciously alter his reputation.

In this paper, we consider the lossy source coding problem with delayed side information at the decoder. We assume that delay is unknown but the maximum of delay is known to the encoder and the decoder, where we allow the maximum of delay to change with the block length. In this coding problem, we show an upper bound and a lower bound of the rate-distortion (RD) function, where the RD function is the infimum of rates of codes in which the distortion between the source sequence and the reproduction sequence satisfies a certain distortion level. We also clarify that the upper bound coincides with the lower bound when maximums of delay per block length converge to a constant. Then, we give a necessary and sufficient condition in which the RD function is equal to that for the case without delay. Furthermore, we give an example of a source which does not satisfy this necessary and sufficient condition.

In this paper, we propose an efficient method for computing the weight spectrum of LDPC convolutional codes based on circulant matrices of quasi-cyclic codes. In the proposed method, we reduce the memory size of their parity-check matrices with the same distance profile as the original codes, and apply a forward and backward tree search algorithm to the parity-check matrices of reduced memory. We show numerical results of computing the free distance and the low-part weight spectrum of LDPC convolutional codes of memory about 130.

Let p be an odd characteristic and m be the degree of a primitive polynomial f(x) over the prime field Fp. Let ω be its zero, that is a primitive element in F*pm, the sequence S={si}, si=Tr(ωi) for i=0,1,2,… becomes a non-binary maximum length sequence, where Tr(·) is the trace function over Fp. On this fact, this paper proposes to binarize the sequence by using Legendre symbol. It will be a class of geometric sequences but its properties such as the period, autocorrelation, and linear complexity have not been discussed. Then, this paper shows that the generated binary sequence (geometric sequence by Legendre symbol) has the period n=2(pm-1)/(p-1) and a typical periodic autocorrelation. Moreover, it is experimentally observed that its linear complexity becomes the maximum, that is the period n. Among such experimental observations, especially in the case of m=2, it is shown that the maximum linear complexity is theoretically proven. After that, this paper also demonstrates these properties with a small example.

In this paper, sequential prediction is studied. The typical assumptions about the probabilistic model in sequential prediction are following two cases. One is the case that a certain probabilistic model is given and the parameters are unknown. The other is the case that not a certain probabilistic model but a class of probabilistic models is given and the parameters are unknown. If there exist some parameters and some models such that the distributions that are identified by them equal the source distribution, an assumed model or a class of models can represent the source distribution. This case is called that specifiable condition is satisfied. In this study, the decision based on the Bayesian principle is made for a class of probabilistic models (not for a certain probabilistic model). The case that specifiable condition is not satisfied is studied. Then, the asymptotic behaviors of the cumulative logarithmic loss for individual sequence in the sense of almost sure convergence and the expected loss, i.e. redundancy are analyzed and the constant terms of the asymptotic equations are identified.

The index generation function is a multi-valued logic function which checks if the given input vector is a registered or not, and returns its index value if the vector is registered. If the latency of the operation is critical, dedicated hardware is used for implementing the index generation functions. This paper proposes a method implementing the index generation functions using parallel index generator. A novel and efficient algorithm called ‘conflict free partitioning’ is proposed to synthesize parallel index generators. Experimental results show the proposed method outperforms other existing methods. Also, A novel architecture of index generator which is suitable for parallelized implementation is introduced. A new architecture has advantages in the sense of both area and delay.

In this paper, we present an area-efficient 4/8/16/32-point inverse discrete cosine transform (IDCT) architecture for a HEVC decoder. Compared with previous work, this work reduces the hardware cost from two aspects. First, we reduce the logical costs of 1D IDCT by proposing a reordered parallel-in serial-out (RPISO) scheme. By using the RPISO scheme, we can reduce the required calculations for butterfly inputs in each cycle. Secondly, we reduce the area of transpose architecture by proposing a cyclic data mapping scheme that can achieve 100% I/O utilization of each SRAM. To design a fully pipelined 2D IDCT architecture, we propose a pipelining schedule for row and column transform. The results show that the normalized area by maximum throughput for the logical IDCT part can be reduced by 25%, and the memory area can be reduced by 62%. The maximum throughput reaches 1248 Mpixels/s, which can support real-time decoding of a 4K × 2K 60fps video sequence.

This paper presents a framework for reducing the energy consumption of embedded real-time systems. We implemented the presented framework as both an optimization toolchain and an energy-aware real-time operating system. The framework consists of the integration of multiple techniques to optimize the energy consumption. The main idea behind our approach is to utilize trade-offs between the energy consumption and the performance of different processor configurations during task checkpoints, and to maintain memory allocation during task context switches. In our framework, a target application is statically analyzed at both intra-task and inter-task levels. Based on these analyzed results, runtime optimization is performed in response to the behavior of the application. A case study shows that our toolchain and real-time operating systems have achieved energy reduction while satisfying the real-time performance. The toolchain has also been successfully applied to a practical application.

While Triple modular Redundancy (TMR) is effective in eliminating soft errors in LSIs, the overhead of the triplicated area as well as the triplicated energy consumption is the problem. In addition to the spatial TMR mode where executions are simply tripricated and the majority is taken, the temporal TMR mode is available where only two copies of an operation are executed and the results are compared, then if the results differ, the third copy is executed to get the correct result. Appropriately selecting the power supply voltage is also an effective technique to reduce the energy consumption. In this paper, a method to derive a TMR design is proposed which selects the TMR mode and supply voltage for each operation to minimize the energy consumption within the time and area constraints.

This article introduces a self-organizing model which builds the topology of a DHT mapping system for ICN. Due to its self-organizing operation and low average degree of maintenance, the management overhead of the system is reduced dramatically, which yields inherent scalability. The proposed model can improve latency by around 10% compared to an existing approach which has a near optimal average distance when the number of nodes and degree are given. In particular, its operation is simple which eases maintenance concerns. Moreover, we analyze the model theoretically to provide a deeper understanding of the proposal.

Using “clean-slate approach” to redesign the Internet has attracted considerable attention. ZNA (Z Network Architecture) is one of clean-slate network architectures based on the layered model. The major features of ZNA are as follows: (1) introducing the session layer to provide the applications with sophisticated communication services, (2) employing inter-node cross-layer cooperation to adapt to the dynamically changing network conditions, (3) splitting the node identifier and the node locator for mobility, multi-homing, and heterogeneity of network layer protocols, (4) splitting the data plane and the control plane for high manageability, and (5) introducing a recursive layered model to support network virtualization. This paper focuses on the first three topics as well as the basic design of ZNA.

As a promising future network architecture, Information-centric networking (ICN) has attracted much attention, its ubiquitous in-network caching is one of the key technologies to optimize the dissemination of information. However, considering the diversity of contents and the limitation of cache resources in the Internet, it is usually difficult to find a one-fit-all caching strategy. How to manage the ubiquitous in-network cache in ICN has become an important problem. In this paper, we explore ways to improve cache performance from the three perspectives of spatiality, temporality and availability, based on which we further propose an in-network cache management strategy to support differentiated service. We divide contents requested in the network into different levels and the selection of caching strategies depends on the content level. Furthermore, the corresponding models of utilizing cache resources in spatiality, temporality and availability are also derived for comparison and analysis. Simulation verifies that our differentiated service based cache management strategy can optimize the utilization of cache resources and get higher overall cache performance.

Tenant network provisioning in multi-tenancy data centers is time-consuming and error-prone due to the need to configure network devices with hundreds of parameter values (e.g., VLAN ID, IP address) determined according to complicated operational rules. Past works have aimed to automate such operational rule-based provisioning processes by implementing data center-specific provisioning programs, but a crucial problem is the high cost of adapting the programs to suit multiple data centers. In this paper, we aim to solve this problem by enabling to describe the provisioning processing, which has been hard-coded programs in conventional approaches, in easy-to-edit “provisioning template” files. The key component of the provisioning template is the parameter decision rule, which is a declarative abstract representation of parameter dependency and parameter assignment. We design the provisioning template so that it can handle various configuration items while preserving its editability for tenant provisioning. We design and implement the provisioning platform, and the evaluation based on a production data center shows that the provisioning platform can adopt multiple data centers with a single program, leading to less development cost compared to past approaches (i.e., program development for each data center).

The energy consumption of the Internet has a huge impact on the world economy and it is likely to increase every year. In present backbone networks, pairs of nodes are connected by “bundles” of multiple physical cables that form one logical link and energy saving can be achieved by shutting down unused network resources. The hose model can support traffic demand variations among node pairs in different time periods because it accommodates multiple traffic matrices unlike the pipe model which supports only one traffic matrix. This paper proposes an OSPF (Open Shortest Path First) link weight optimization scheme to reduce the network resources used for the hose model considering single link failures. The proposed scheme employs a heuristic algorithm based on simulated annealing to determine a suitable set of link weights to reduce the worst-case total network resources used, and considering any single link failure preemptively. It efficiently selects the worst-case performance link-failure topology and searches for a link weight set that reduces the worst-case total network resources used. Numerical results show that the proposed scheme is more effective in the reduction of worst-case total network resources used than the conventional schemes, Start-time Optimization and minimum hop routing.

This study proposes a novel method for evaluating the transmission characteristics of a three-phase filter using the “Fortescue-mode S-parameters,” which are S-parameters whose variables are transformed into symmetrical coordinates (i.e., zero-/positive-/negative-phase sequences). The behavior of the filter under three-phase current, including its non-symmetry, can be represented by these S-parameters, without regard to frequency. This paper also describes a methodology for creating modal equivalent circuits that reflect Fortescue-mode S-parameters allowing the effects of circuit components on filter characteristics to be estimated. Thus, this method is useful not only for the measurement and evaluation but also for the analysis and design of a three-phase filter. In addition, the physical interpretation of asymmetrical/symmetrical insertion losses and the conversion method based on Fortescue-mode S-parameters are clarified.

To support the processing of spatial window queries efficiently in a non-flat wireless data broadcasting system, we propose a Two-Tier Spatial Index (TTSI) that uses a two tier data space to distinguish hot and regular data items. Unlike an existing index which repeats regular data items located near hot items at the same time as the hot data items during the broadcast cycle, TTSI makes it possible to repeat only hot data items during a cycle. Simulations show that the proposed TTSI outperforms the existing scheme with respect to access time and energy consumption.

Radar systems using ultra-wideband (UWB) signals have definitive advantages in high range resolution. These are suitable for accurate 3-dimensional (3-D) sensing by rescue robots operating in disaster zone settings, where optical sensing is not applicable because of thick smog or high-density gas. For such applications, where no a priori information of target shape and position is given, an accurate method for 3-D imaging and motion estimation is strongly required for effective target recognition. In addressing this issue, we have already proposed a non-parametric 2-dimensional (2-D) imaging method for a target with arbitrary target shape and motion including rotation and translation being tracked using a multi-static radar system. This is based on matching target boundary points obtained using the range points migration (RPM) method extended to the multi-static radar system. Whereas this method accomplishes accurate imaging and motion estimation for single targets, accuracy is degraded severely for multiple targets, due to interference effects. For a solution of this difficulty, this paper proposes a method based on a novel matching scheme using not only target points but also normal vectors on the target boundary estimated by the Envelope method; interference effects are effectively suppressed when incorporating the RPM approach. Results from numerical simulations for both 2-D and 3-D models show that the proposed method simultaneously achieves accurate target imaging and motion tracking, even for multiple moving targets.

The physical optics (PO) approximation is one of the widely-used techniques to calculate scattering fields with a reasonable accuracy in the high frequency region. The computational load of PO radiation integral dramatically increases at higher frequencies since it is proportional to the electrical size of scatterer. In order to suppress this load, a variety of techniques, such as the asymptotic evaluation by the stationary phase method (SP), the equivalent edge currents (EECs), the low-order polynomial expansion method and the fast physical optics (FPO), have been proposed and developed. The adaptive sampling method (ASM) proposed by Burkholder is also one of the techniques where the sampling points in radiation integral should be adaptively determined based upon the phase change of integrand. We proposed a quite different approach named ``Localization of the radiation integrals.'' This localization method suggests that only the small portions of the integration with a slow phase change contribute to the scattering field. In this paper, we newly introduce the ASM in the localization method and applied the proposed method into the radar cross section (RCS) analysis of 2-dimensional strip and cylinder. We have confirmed that the proposed method provides the frequency-independent number of division in the radiation integrals and computational time and accuracy. As the starting point for extension to 3-D case, the application of the proposed method for a reflection from an infinite PEC plane and a part of sphere was also examined.