This paper presents a computationally efficient subspace-based method for partially adaptive beamforming which is based on the structure of the generalized sidelobe canceller (GSC). Its auxiliary beamformer operates in an estimated interference subspace which is obtained through simple computation. The computational burden of the proposed method in terms of complex multiplication is just on O(η2M) where η and M are the numbers of interferences and the array elements, respectively. Though the subspace obtained is different from the exact interference subspace due to the presence of noise, theoretical analysis shows that the proposed beamfomer virtually attains the optimal performance for strong or sidelobe interference. Simulation results validate its effectiveness including fast convergence, even in the presence of errors in the detected number of directional signals.

IPv6 is realized as the next generation internet platform, succeeding the current IPv4 internet environment. Linux, one of the major operating systems, has supported IPv6 since 1996, however, the quality of the protocol stack has not been good enough for professional operation. In this paper, we show our IPv6 stack implementation design regarding the neighbor management in Neighbor Discovery Protocol (NDP), the routing table management and the packet processing using XFRM architecture. The implementation is designed based on the Serialized Data State Processing, which aims at simpler object management so as to achieve stable, flexible and extensible IPv6 stack. According to the TAHI IPv6 Protocol Conformance Test Suite, we can show our implementation achieves enough implementation quality.

In this letter, we present the new type parallel-coupled band-pass filter (BPF) which uses the dielectric guide in coupled sections with finite metallization thickness. A mode-matching method has been used to analyze this new structure and the simulation results are shown and validated through comparison with other available data. The results in this letter show that the dielectric guide of coupled lines with finite metal strips can be newly added to the design parameters of the parallel-coupled BPF structure and other microwave applications.

Conventional vector quantization (VQ) encoding method by full search (FS) is very heavy computationally but it can reach the best PSNR. In order to speed up the encoding process, many fast search methods have been developed. Base on the concept of multi-resolutions, the FS equivalent fast search methods using mean-type pyramid data structure have been proposed already in. In this Letter, an enhanced sum pyramid data structure is suggested to improve search efficiency further, which benefits from (1) exact computing in integer form, (2) one more 2-dimensional new resolution and (3) an optimal pair selecting way for constructing the new resolution. Experimental results show that a lot of codewords can be rejected efficiently by using this added new resolution that features lower dimensions and earlier difference check order.

This paper introduces a power-efficient on-chip DC-DC converter, which produces a 1.0 V output by being stepped-down from a 3.6 V input, utilizes a 10 µH external inductor, and realizes more than 80% power-efficiency. In order to realize a 1.0 V output without decreasing power-efficiency, a synchronous-type rectifier scheme with a reverse current protection circuit is adopted and a reference voltage of less than 1.0 V is developed. The external inductor value is reduced by applying the PWM control scheme and a new low-power 1 MHz triangular waveform oscillator. High-value resistors are used in analog circuits including a voltage reference, a triangular waveform oscillator, an error amplifier, and a comparator to have the ultra-low power characteristics. A chip is actually designed and fabricated by using the 2 µm CMOS process. As a result, a 1 MHz, synchronous, step-down from 3.6 V to 1 V, PWM DC-DC converter has been realized with a power efficiency of more than 80% in the output current range from 40 to 70 mA.

This paper provides a review on the optimal design of photonic bandgap structures by inverse problem techniques. An overview of inverse problems techniques is given, with a special focus on topology design methods. A review of first applications of inverse problems techniques to photonic bandgap structures and waveguides is given, as well as some model problems, which provide a deeper insight into the structure of the optimal design problems.

Autonomous Decentralized Community Information System (ADCS) is a proposition made to meet the rapidly changing users' requirements and cope with the extreme dynamism in current information services. ADCS is a decentralized architecture that forms a community of individual end-users (community members) having the same interests and demands in specified time and location. It allows those members to mutually cooperate and share information without loading up any single node excessively. In this paper, an autonomous decentralized community communication technology is proposed to assure a productive cooperation, a flexible and timely communication among the community members. The main ideas behind this communication technology are: content-code communication (service-based) for flexibility and multilateral communication for timely and productive cooperation among members. All members communicate productively for the satisfaction of all the community members. The scalability of the system's response time regardless of the number of the community members is shown through simulation. Thus, the autonomous decentralized community communication technology reveals significant results when the total number of members in the community increases sharply.

We propose two new adaptive minimum symbol error rate algorithms based on biased and unbiased decision rule respectively for M-ary PAM equalizer systems. The proposed algorithms can be processed either on-line or off-line depending on the availability of the information on channel impulse response. Comparisons are made between our algorithms with other existing algorithms. Computer simulations are performed to present performance results and some important algorithm properties including the effect of varying equalizer length and SNR values.

A time-domain equalization (TEQ) algorithm is presented to shorten the effective channel impulse response to increase the transmission efficiency of the 54 Mbps IEEE 802.11a orthogonal frequency division multiplexing (OFDM) system. In solving the linear equation Aw = B for the optimum TEQ coefficients, A is shown to be Hermitian and positive definite. The LDLT and LU decompositions are used to factorize A to reduce the computational complexity. Simulation results show high performance gains at a data rate of 54 Mbps with moderate orders of TEQ finite impulse response (FIR) filter. The design and implementation of the algorithm in field programmable gate array (FPGA) are also presented. The regularities among the elements of A are exploited to reduce hardware complexity. The LDLT and LU decompositions are combined in hardware design to find the TEQ coefficients in less than 4 µs. To compensate the effective channel impulse response, a radix-4 pipeline fast Fourier transform (FFT) is implemented in performing zero forcing equalization. The hardware implementation information is provided and simulation results are compared to mathematical values to verify the functionalities of the chips running at 54 Mbps.

We present master-slave pulse-coupled bifurcating neurons having refractoriness. The system can exhibit various phenomena, e. g. , periodic and chaotic in-phase synchronizations, and periodic out-of-phase synchronization. We clarify local stabilities of the phenomena and a sufficient condition for the in-phase synchronization. It is suggested that bifurcations of the synchronization phenomena may relate to detection of a master parameter, and the refractoriness may relate to control of the detection accuracy. Using a simple test circuit, typical phenomena are verified in the laboratory.

A new mobility management architecture is proposed to optimize end-to-end routes for mobile nodes (MNs) and mobile routers (MRs) within a nested mobile network environment. By applying local network mobility management mechanisms based on Hierarchical Mobile IPv6 (HMIPv6) to a mobile network, the proposed approach can optimize the route to the mobile network effectively. Combining the proposed route optimization methods and HMIPv6 functionality can enable it to provide more effective route optimization, reducing the burden of location registration for handovers. A route optimization method for local fixed nodes in a mobile network has also been developed by adding proxy mobile node and correspondent node functions to the MRs. Numerical evaluations on mean route length and traffic routed through network nodes demonstrate the effectiveness and applicability of the proposed methods especially in large-scale networks.

Recent progress on photonic crystal fibers is reviewed aiming at their application to high performance networks. A photonic crystal fiber has an array of air holes surrounding the silica core region. Light is confined to the core by the refractive index difference between the core and the array of air holes. Photonic crystal fibers have special characteristics compared with conventional single mode fibers. One is that the dispersion characteristics can be designed. Another characteristic, that strong birefringence can be established by sizing and/or arranging the air holes, is expected to realize a polarization maintaining fiber with high birefringence of the order of 110-3. This paper will describe the characteristics of dispersion controlled PCFs and polarization maintaining PCFs that include supercontinuum generation and absolute single polarization characteristics for various types of optical devices in high performance network systems.

Online and realtime traffic summarization is a challenge as, except for the routine cases, aggregation parameters or, the flows that need to be observed are not known a priori. Dynamic adaptive aggregation algorithms adapt to the network traffic to detect the important flows. But present day algorithms are inadequate as they often produce inaccurate or meaningless aggregates. In this work we propose a Dynamic Constrained Adaptive Aggregation algorithm that does not produce the meaningless aggregates by using information about the network's configuration. We compare the performance of this algorithm with the erstwhile Dynamic (Unconstrained) Adaptive Aggregation algorithm and show its efficacy. Further we use the network map context that shows the network flows in an intuitive manner. Several applications of the algorithm and network map based visualization are discussed.

Recent new technologies of electro-mechanical conversion devices have been reviewed. Especially, the electrochemical properties of anisotropic actuators using polypyrrole have been reviewed in detailed and the realization of the bimorph (or bending beam) structure without artificial adhesive agent is introduced.

In this paper we describe a method for the automated design of analog circuits. The method simultaneously sizes the different components (transistors, capacitors, etc.) in a pre-defined circuit topology and places them according to a pre-defined slicing tree. The method is based on formulating the circuit physical and electrical behavior in a special convex form. More specifically, we cast the design problem as a geometric program, a special type of convex optimization problem. Therefore, all design constraints are formulated as posynomial inequality or monomial equality constraints. Very efficient numerical algorithms are then used to solve the resulting geometric program and to create the design that meets the desired specifications. The formulation is hierarchical and modular, allowing easy topology re-use and process porting. The synthesis method is fast, and determines the globally optimal design; in particular the final solution is completely independent of the starting point, and infeasible specifications are unambiguously detected. After a brief overview of current analog design automation solutions, we describe our method and provide some design examples for op-amps and analog-to-digital converters.

SMIL is a markup language which enables us to describe multimedia contents. This paper proposes a design model of SMIL browser functionality for mobile phones whose resources are limited. We introduce SMIL Component, which is based on attachable software architecture to a pre-installed generic web browser and an event-based SMIL scheduler, which is a part of SMIL Component, to provide the multimedia presentation scheduling functionality. These lead to reducing the memory amount that SMIL Component consumes and brings high portabilty of SMIL Component for various web browsers. We implement SMIL Component and evaluate RAM sizes and presentation delays. As a result, we conclude that SMIL Component is practical for MMS presentations on a mobile phone.

In this paper, a new class of bent functions is constructed by combining class M and class C bent functions. Using the construction method of the class D bent functions defined on the binary vector space, new p-ary generalized bent functions are also introduced for odd prime p.

The matrix inequality condition has been considered as the main condition for the stability of RHC. But it is difficult to apply the matrix inequality condition for guaranteeing the stability of any physical system because of the high gain problem brought about the high value of the final state weighting matrix. Therefore, in this study, a new stability condition for RHC is proposed and it extends the range of the final state weighting matrix guaranteeing the stability of RHC in comparison with the case of the matrix inequality condition. The proposed stability condition is based not only on a final state weighting matrix but also on a horizon size and guarantees the stability for other forms of model predictive control just like the matrix inequality condition.

In this paper, using p-ary bent functions defined on vector space over the finite field Fpk, we generalized the construction method of the families of p-ary bent sequences with balanced and optimal correlation properties introduced by Kumar and Moreno for an odd prime p, called generalized p-ary bent sequences. It turns out that the family of balanced p-ary sequences with optimal correlation property introduced by Moriuchi and Imamura is a special case of the newly constructed generalized p-ary bent sequences.

In order to transport an ever-increasing amount of IP traffic effectively, Photonic IP networks that employ wavelength routing and Layer 3 cut-through are very important. This paper proposes a new network design algorithm that minimizes the network cost considering IP traffic growth for multi-layered photonic IP networks that comprise electrical label switched paths (LSPs) and optical LSPs. We evaluate the network cost obtained from the developed network design algorithm that considers IP traffic growth and compare it to the results obtained from a static zero-based algorithm. The static zero-based algorithm does not take into account the history of progressive past IP traffic changes/growth until that time. The results show that our proposed algorithm is very effective; the cost increase from the cost obtained using the zero-based algorithm is marginal. The algorithm developed herein enables effective multi-layered photonic IP network design that can be applied to practical networks where IP traffic changes/increases progressively and that can be used for long term network provisioning.