This letter proposes a compact multi-layered bandpass filter exhibiting left-handed and right-handed behaviors in its passband. This filter has a greatly expanded passband from 1.61 GHz to 4.16 GHz (88.4% bandwidth) with a maximum ripple of 1.2 dB and well-suppressed out-of-passbands with transmission zeros at 1.15 GHz and 4.52 GHz. The physical mechanisms are studied with FEM-based full-wave simulations, equivalent circuit analysis and careful experiments.

This letter presents mutual coupling reduction in an E-plane arranged microstrip patch array fed by a triplate waveguide. Five mushroom-like electromagnetic band-gap (EBG) elements arranged in one column are embedded both between two radiating patches and between the feeding lines for suppression of the surface wave and the parallel plate mode, respectively. Validity of the proposed EBG elements is confirmed by the measurement.

Efficient group rekeying is an important issue for secure group communications. Most of the proposed group rekeying methods require expensive encryption and decryption operations to rekey the group. However, in a model where a trusted server is used to distribute group keys, the trusted server may become a bottleneck because of the expensive computation operations, such as encryption, that it has to perform. In this paper, we propose a new stateless group rekeying scheme to solve the multicast group rekeying problem. In our proposed scheme, the trusted server combines mask-based key-location hiding with the simple XOR-encryption using secret hash values to rekey the group. Without affecting the system security, our approach reduces the processing cost of the trusted server by eliminating the need to encrypt the group key. Moreover, to acquire the group key, the computational cost of the group members is low and stable regardless of the rekeying message size.

This letter develops theoretical analysis of the normalized LMS algorithm (NLMSA) for use in complex-domain adaptive filters in the presence of impulse noise at filter input. We propose a new "stochastic" model for such impulse noise, and assume that filter reference input process is a white process, e.g., digital QAM data, White & Gaussian process, etc. In the analysis, we derive a simple difference equation for mean square tap weight misalignment (MSTWM). Experiment is carried out to demonstrate effectiveness of the NLMSA in robust filtering in the presence of the impulse noise at the filter input. Good agreement between simulated and theoretically calculated filter convergence, in a transient phase as well as in a steady-state, proves the validity of the analysis.

In this paper, we present a resource monitoring and selection method for rapid turnaround grid applications (for example, within 10 seconds). The novelty of our method is the distributed evaluation of resources for rapidly selecting the appropriate idle resources. We integrate our method with a widely used resource management system, namely the Monitoring and Discovery System 2 (MDS2), and compare our method with the original MDS2 in terms of the performance and the scalability. The performance is measured using a 64-node cluster of PCs and the scalability is analyzed using a theoretical model and the measured performance. The experimental results show that our method reduces the resource selection time by 82%, as compared with the original MDS2. The scalability analysis also indicates that our method can keep the resource selection time within 1 second, up to 500 nodes in local-area-network (LAN) environments. In addition, some simulation results are presented to estimate the impact of our method for wide-area-network (WAN) environments.

This paper presents two kinds of new ZCZ codes consisting of trios of two binary sequences and a bi-phase sequence, which can reach the upper bound on the ZCZ codes. From the viewpoint of sequence design, it is shown that they can provide the most effective ASK-CDMA system, which can remove co-channel interference.

This letter presents parametric uncertainty bounds (PUBs) for stabilizing receding horizon H∞ control (RHHC). The proposed PUBs are obtained easily by solving convex optimization problems represented by linear matrix inequalities (LMIs). We show, by numerical example, that the RHHC can guarantee a H∞ norm bound for a larger class of uncertain systems than conventional infinite horizon H∞ control (IHHC).

Large-throughput anomaly prevention mechanism in the upstream side of high-speed (over 10-Gbps) networks is required to prevent various anomalies such as distributed denial of service (DDoS) from causing various network problems. This mechanism requests the processors achieving not only high-speed response for analyzing many packets in a short time but also the flexibility to update the anomaly prevention algorithm. In this research, I assumed a dynamic reconfigurable processor (DRP) was most effective in achieving this anomaly prevention mechanism, for processors used in nodes with the mechanism, and I designed an anomaly prevention mechanism using DRPs. The mechanism can shorten anomaly prevention time in high-speed (10 Gbps) lines using an all-packet analysis. Through a simulation, I achieved the goal of the mechanism achieving a throughput of 83-M packets per second using three DRPs (432 execution elements used). Moreover, with the prototype, it was confirmed that the proposed mechanism prevented anomalies in a short time (constant 0.01 second), which was 3000 times faster than that of a legacy mechanism using a packet sampling method. I also proposed integrated prevention, which was able to reduce the number of execution elements comprising anomaly prevention algorithm against various kinds of anomalies. It was achieved with a simulation that the proposed integrated prevention against three kinds of anomalies (DDoS, worm, and peer to peer (P2P)) reduced the number of execution elements by 24% compared to legacy prevention. In addition, non-stop update was proposed to maintain throughput when updating an anomaly prevention algorithm without packet loss. It was confirmed with a simulation that there was enough time for non-stop update in 10 Gbps 4 lines.

A novel planar composite right/left handed (CRLH) transmission line (TL) with double-sided metal patterns, which is advantageous in high scalability and low-cost fabrication, is proposed. Fundamental characteristics of the unbalanced and balanced CRLH TLs are confirmed numerically and theoretically both by full-wave finite-element method (FEM) simulations and the equivalent circuit analysis in terms of dispersion characteristics and characteristic impedances for the periodic structure. It is also shown that the relations between the left-handed circuit parameters and the geometrical parameters of the unit cell are simple and intuitive, which is useful for designing the CRLH TL. Experiments on 10-cell unbalanced and balanced CRLH TLs are carried out and the left-handed and right-handed wave propagations are confirmed by scattering parameter and near field measurements.

We propose here a composite right/left handed transmission line constructed by using conductor-backed coplanar strips. In this line, we can easily realize a shunt inductor without via because it has the electric-wall symmetry at the guide center. The left-handed nature is verified by both the finite difference time-domain (FDTD) and the equivalent-circuit calculations. Furthermore, we demonstrate the proposed line can easily satisfy the balanced condition for no band gap between the right-handed and the left-handed modes, and can be applied to a leaky-wave antenna, numerically and experimentally.

Overlay networks are expected to be a promising technology for the realization of QoS (Quality of Service) control. Overlay networks have recently attracted considerable attention due to the following advantages: a new service can be developed in a short duration and it can be started with a low cost. The definition and necessity of the overlay network is described, and the classification of various current and future overlay networks, particularly according to the QoS feature, is attempted. In order to realize QoS control, it is considered that routing overlay and session overlay are promising solutions. In particular, session and overlay networks are explained in detail since new TCP protocols for QoS instead of current TCP protocols that control congestion in the Internet can be used within overlay networks. However, many open issues such as scalability still need further research and development although overlay networks have many attractive features and possess the potential to become a platform for the deployment of new services.

Binary sequences with two-level periodic autocorrelation correspond directly to cyclic (v, k, λ)-designs. When v = 4t-1, k = 2t -1 and λ = t-1, for some positive integer t, the sequence (or design) is called a cyclic Hadamard sequence (or design). For all known examples, v is either a prime number, a product of twin primes, or one less than a power of 2. Except when v = 2k-1, all known examples are based on quadratic residues (using the Legendre symbol when v is prime, and the Jacobi symbol when v = p(p+2) where both p and p+2 are prime); or sextic residues (when v is a prime of the form 4a2 + 27). However, when v = 2k-1, many constructions are now known, including m-sequences (corresponding to Singer difference sets), quadratic and sextic residue sequences (when 2k-1 is prime), GMW sequences and their generalizations (when k is composite), certain term-by-term sums of three and of five m-sequences and more general sums of trace terms, several constructions based on hyper-ovals in finite geometries (found by Segre, by Glynn, and by Maschietti), and the result of performing the Welch-Gong transformation on some of the foregoing.

To increase the yield of data processing circuits such as adders and logic operation circuits, the bit-slice reconfiguration design has been proposed as an efficient redundant technology for defect-tolerance. Wallace multipliers are a well-known class of high-speed parallel multipliers. Unfortunately, the bit-slice reconfiguration design is not applicable to Wallace multipliers because Wallace multipliers do not have regular bit-slice structure. Therefore, redundant designs for Wallace multipliers have been regarded impossible. This paper proposes a redundant design for Wallace multipliers. In order to design redundant Wallace multipliers, first, 2n heterogeneous slices are considered in a non-redundant nn Wallace multiplier. The proposed redundant Wallace multipliers contain reconfigurable slices which can play the role of both i-th and (i+1)-th slices. Since the i-th slice has a similar structure to the (i+1)-th slice, the reconfigurable slice is not much larger than the i-th slice. This paper also shows a repair procedure for the proposed design. This paper evaluates the proposed design from the viewpoint of the yield, area, effective yield and delay time. For example, the yield of a 3232 Wallace multiplier increases from 0.30 to 0.41 by applying the proposed design while the area increases by a factor of 1.21.

Nonlinear modeling of complex irregular systems constitutes the essential part of many control and decision-making systems and fuzzy logic is one of the most effective algorithms to build such a nonlinear model. In this paper, a new approach to fuzzy modeling is proposed. The model considered herein is the well-known Sugeno-type fuzzy system. The fuzzy modeling algorithm suggested in this paper is composed of two phases: coarse tuning and fine tuning. In the first phase (coarse tuning), a successive clustering algorithm with the fuzzy validity measure (SCFVM) is proposed to find the number of the fuzzy rules and an initial fuzzy model. In the second phase (fine tuning), a moving genetic algorithm with partial encoding (MGAPE) is developed and used for optimized tuning of membership functions of the fuzzy model. Two computer simulation examples are provided to evaluate the performance of the proposed modeling approach and compare it with other modeling approaches.

File-sharing Peer-to-Peer systems are effective for autonomous data retrieval and provision over the networks. However, the early data retrieval schemes such as Gnutella and Local Indices have low performance and large overhead. In order to solve weakness of early schemes, this paper proposes a dynamic scheme for data retrieval and provision, in which indices are adaptively allocated in appropriate nodes to variation of traffic patterns caused by query messages. The simulation experimental results show that the proposed scheme has good performance with reasonable overhead even when the traffic patterns vary as time proceeds.

Electromagnetic crystals formed by vertical full posts stacked in a rectangular waveguide are analyzed using the image theory and the lattice sums technique. It is shown that the frequency response of the crystals consisting of circular posts can be obtained by a simpler matrix calculus based on the one-dimensional lattice sums, the T-matrix of a circular cylinder in free space, and the generalized reflection and transmission matrices.

Eigenvalue equations and expressions of EM fields for volume modes in an anisotropic single-negative slab with tensor material parameters is presented. By the comparison with the eigenvalue equation of surface modes along single-negative slab with negative scalar permeability, the validity of the present study is confirmed. We have also made clear which elements of the material parameter tensors affect existence of TE and TM modes in the slab. Taking the dispersion of material parameters into consideration, we demonstrate in detail that TE modes propagate in a slab with one negative element of the permeability tensor numerically. These TE modes turn out to be the magnetostatic waves (MSWs), which is the first demonstration of the MSW in a nonmagnetic material.

A brief review of metamaterials and their applications to antenna systems is given. Artificial magnetic conductors and electrically small radiating and scattering systems are emphasized. Single negative, double negative, and zero-index metamaterial systems are discussed as a means to manipulate their size, efficiency, bandwidth, and directivity characteristics.

In order to introduce new routing functionality without changing the Internet infrastructure, many routing overlays have been proposed in recent years. Although such overlays allow us to dynamically and flexibly form various types of networks, the current host name resolution mechanism used in the Internet, i.e. DNS, cannot provide us such flexibility in host name referencing because of its delegation-based administration scheme of domain names. And also, it cannot provide us security because of the lack of wide deployment of its security extension, DNSSEC. In this paper, we propose a generic framework for secure and flexible host name resolution infrastructure that can be shared among many routing overlays. In contrast to DNS with which users are forced to use the domain name space managed by IANA/ICANN, our framework separates the name resolution mechanism from the name spaces it handles, which allows users to choose whatever name space they think appropriate for the identity scheme of their overlay-networking community. This realizes decentralized management of domain names and gives users freedom in domain name acquisition. The basic idea to achieve this is to use a cryptographically generated identifier (i.e. a hash of a public key) as a reference to an administrative domain of overlay networking hosts and allow the owner of the domain to securely publish host information using the corresponding private key. We show that a referencing mechanism for such host information can be easily implemented by using distributed hash tables (DHTs), and then show how such "semantic-free" references to domains can be linked to existing identity scheme in order to allow "human-friendly" referencing.

JPEG2000, an international standard for still image compression, offers 1) high coding performance, 2) unified lossless/lossy compression, and 3) resolution and SNR scalability. Resolution scalability is an especially promising attribute given the popularity of Super High Definition (SHD) images like digital-cinema. Unfortunately, its current implementation of resolution scalability is restricted to powers of two. In this paper, we introduce non-octave scalable coding (NSC) based on the use of filter banks. Two types of non-octave scalable coding are implemented. One is based on a DCT filter bank and the other uses wavelet transform. The latter is compatible with JPEG2000 Part2. By using the proposed algorithm, images with rational scale resolutions can be decoded from a compressed bit stream. Experiments on digital cinema test material show the effectiveness of the proposed algorithm.