The fairness algorithm of the Resilient Packet Ring IEEE 802.17 standard suffers from throughput degradation under an unbalanced overload. This letter proposes an enhanced fairness algorithm using a valuable piece of information, represented by the transit buffer length, about congestion alleviation on a congested node, under which the throughput degradation can be completely improved.

Broadening the frequency bandwidth of antennas has been one of the major subjects concerning antenna design technologies. Two of the major subjects for microstrip antennas, which appeared in the 1970s, have also been the broadening of the frequency bandwidth and the sharing of multifrequency bands. In this paper, we describe the broadband and multiband techniques of printed antennas, and show the configurations of realized broadband and multiband antennas and their characteristics. Here, resonant-type microstrip antennas, planar monopole antennas, fractal antennas and ultra-wideband printed antennas are introduced. The optimum design techniques using a genetic algorithm are introduced for developing broadband and multiband printed antennas. The usefulness of this method is verified by the simulation and experimental results of the fabricated planar monopole antenna which has ultrawide-band characteristics.

This paper discusses the least-squares linear filtering and fixed-lag smoothing problems of discrete-time signals from uncertain observations when the random interruptions in the observation process are modelled by a sequence of not necessarily independent Bernoulli variables. It is assumed that the observations are perturbed by white noise and the autocovariance function of the signal is factorizable. Using an innovation approach we obtain the filtering and fixed-lag smoothing recursive algorithms, which do not require the knowledge of the state-space model generating the signal. Besides the observed values, they use only the matrix functions defining the factorizable autocovariance function of the signal, the noise autocovariance function, the marginal probabilities and the (2,2)-element of the conditional probability matrices of the Bernoulli variables. The algorithms are applied to estimate a scalar signal which may be transmitted through one of two channels.

This paper proposes a Voice Activity Detection (VAD) algorithm using Radial Basis Function (RBF) network. The k-means clustering and Least Mean Square (LMS) algorithm are used to update the RBF network to the underlying speech condition. The inputs for RBF are the three parameters a Code Excited Linear Prediction (CELP) coder, which works stably under various background noise levels. Adaptive hangover threshold applies in RBF-VAD for reducing error, because threshold value has trade off effect in VAD decision. The experimental results show that the proposed VAD algorithm achieves better performance than G.729 Annex B at any noise level.

Anycast refers to the transmission of data from a source node to (any) one member in the group of designed recipients in a network. When the physical network and the set of anycast requests are given, the WDM anycast routing problem (WARP) is to find a set of light-paths, one for each source, for anycasting messages to one of the member in the anycast destination group such that not any path using the same wavelength passes through the same link. The goal of the WARP is to minimize the number of used wavelengths. In this paper, the WARP is formulated and studied, since WARP is NP-hard, several heuristic algorithms and a hybrid method which combines heuristic and simulated annealing techniques are proposed to solve it. These algorithms are used to find the close-to-optimal solution. Simulated results show that the proposed algorithms are able to achieve good performance.

This paper presents an approach of logic mapping into LUT-Array-Based PLD where Boolean functions in the form of the sum of generalized complex terms (SGCTs) can be mapped directly. While previous mapping approach requires predetermined variable ordering, our approach performs mapping and variable reordering simultaneously. For the purpose, we propose a directed acyclic graph based on the multiple-valued decision diagram (MDD) and an algorithm to construct the graph. Our algorithm generates candidates of SGCT expressions for each node in a bottom-up manner and selects the variables in the current level by evaluating the sizes of SGCT expressions directly. Experimental results show that our approach reduces the number of terms maximum to 71 percent for the MCNC benchmark circuits.

Penumbral imaging is a technique which exploits the fact that spatial information can be recovered from the shadow or penumbra that an unknown source casts through a simple large circular aperture. Since the technique is based on linear deconvolution, it is sensitive to noise. In this paper, a two-step method is proposed for decoding penumbral images: first, a noise-reduction algorithm based on ICA-domain (independent component analysis-domain) shrinkage is applied to smooth the given noise; second, the conventional linear deconvolution follows. The simulation results show that the reconstructed image is dramatically improved in comparison to that without the noise-removing filters, and the proposed method is successfully applied to real experimental X-ray imaging.

A novel CMOS LC oscillator architecture combining an LC tuned oscillator and a ring structure is presented as a new design topology to deliver improved phase noise for multiphase applications. The relative enhancement in the phase noise is estimated using a linear noise modeling approach. A three-stage LC-ring oscillator fabricated in a 0.6 mm CMOS technology achieves measured phase noise of -132 dBc/Hz at 600 kHz offset from a 900 MHz carrier and dissipates 20 mW with a 2.5 V power supply.

Broadband fixed wireless access (BFWA) systems with multi-hop mesh topologies have attracted considerable attention as a promising technology for next generation, high quality, high capacity, and high density access infrastructures. The primary advantages of mesh network topologies are an improvement of capacity by means of traffic engineering throughout the networks. This paper discusses an adaptive traffic load balancing method that maximizes the capacity for the mesh BFWA networks. Taking into account the variation of network conditions such as traffic demand distributions and qualities of wireless links, the adaptive traffic load balancing method attempts to equalize the utilization of capacity for each wireless link. To avoid deteriorating the performance of TCP communications, the proposed method implements flow-based traffic load balancing. Performance of the proposed adaptive traffic load balancing method is demonstrated and validated using the experimental mesh network environments with wired networks with up to sixteen nodes that emulates the variation of the wireless link capacity.

In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fiber Raman amplifier is analyzed. Expressions are present for both forward pumping and backward pumping schemes, respectively. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The best isolator position is determined as 13 km away from the signal input end for forward pumping, and 9 km from the output end for backward pumping. The best position is found insensitive to the fiber length, pump power, and signal power. When the isolator is on the best position, the DRB noise can be reduced by almost 2 to 3 orders.

In this paper, a Web-based management system for the building network is described. We developed a multi-protocol converter based on SoC and embedded Linux. It requires an appropriate operating system for handling protocols and an advanced development environment very similar to embedded linux. The multi-protocol converter integrates control networks of RS-485 and LonWorks devices to BAS through TCP/IP protocol or a client with Java applet. The system consists of three-tier architecture, such as BAS or clients, a multi-protocol converter, and control devices. In order to compare the feasibility of system architecture, it was applied to a small BAS system. By using UML, we modeled a Web-based control system with a unified TCP/IP socket communication and the system architecture. The developed system includes the inverter motor control system with modbus protocol for the RS485 network. The experiment results show that the multi-protocol converter using embedded Linux is a flexible and effective way to build a Web-based monitoring and control system.

Process-centered software engineering environments (PSEEs) facilitate controlling complicated software processes. Traditional PSEEs are generally centrally controlled, which may result in the following drawbacks: (1) the server may become a bottleneck and (2) when the server is down, processes need to be suspended. To overcome the drawbacks, we developed a decentralized process engine ADPE (agent-based decentralized process engine). ADPE can be embedded in any PSEE to decentralize the PSEE. This paper presents ADPE.

This paper considers the problem of recursive filtering for linear discrete-time systems with uncertain observation. A new approximate adaptive filter with a parallel structure is herein proposed. It is based on the optimal mean square combination of arbitrary number of correlated estimates which is also derived. The equation for error covariance characterizing the mean-square accuracy of the new filter is derived. In consequence of parallel structure of the filtering equations the parallel computers can be used for their design. It is shown that this filter is very effective for multisensor systems containing different types of sensors. A practical implementation issue to consider this filter is also addressed. Example demonstrates the accuracy and efficiency of the proposed filter.

This paper presents an optimal load balancing algorithm based on both of the ANFIS (Adaptive Neuro-Fuzzy Inference System) modeling and the FIS (Fuzzy Inference System) for the local status of real servers. It also shows the substantial benefits such as the removal of load-scheduling overhead, QoS (Quality of Service) provisioning and providing highly available servers, provided by the suggested method.

Communications in locally structured wireless networks, such as ad hoc networks, will play an important role for network services and applications in the ubiquitous networking environments of the future. Most of the time, however, mobile networks are used in much the same way as fixed networks: most of the time, mobile terminals merely access information which is stored in the backbone network. Applications based on the local exchange of information gathered or generated by mobile terminals will open up many novel possibilities. A new online storage system named CAOSS facilitates such exchange and constitutes a building block for various new applications. CAOSS is a server-less system that provides high availability of data in mobile and wireless network environments. We describe CAOSS and its application in a mobile video-information-sharing system named GT. Thanks to the good performance of CAOSS, the GT system gives users a convenient and easy way to share and accumulate video data in a wireless environment. We confirm that CAOSS has strong enough performance to deal with large volumes of video data.

Large-capacity photonic packet switch using the wavelength division multiplexing (WDM) technology is proposed. In this switch, the optical buffers, consisting of the fiber delay lines, are shared in many input ports by using the WDM. Furthermore, to reduce the number of optical buffers, the speed-up effect in the optical switch part is investigated. A high-speed tunable optical filter incorporating a semiconductor ring resonator is a key device in the proposed packet switch because many optical filters are used. Optical ring resonators should be possible to fabricate them at a low cost because of their simple structure. To achieve a wide tuning range we designed a double-ring structure, in which two ring resonators are connected in series, and fabricated it using the InGaAsP-InP material system. This device exhibits a total free spectral range (FSR) of 1.7 THz and contrast ratio of 9.5 dB. The ring radii are 25.2 and 17.8 µm, which correspond to FSRs of 340 and 425 GHz, respectively. The switching time of the device is 2.5 ns.

This paper describes continuous speech recognition incorporating the additional complement information, e.g., voice characteristics, speaking styles, linguistic information and noise environment, into HMM-based acoustic modeling. In speech recognition systems, context-dependent HMMs, i.e., triphone, and the tree-based context clustering have commonly been used. Several attempts to utilize not only phonetic contexts, but additional complement information based on context (factor) dependent HMMs have been made in recent years. However, when the additional factors for testing data are unobserved, methods for obtaining factor labels is required before decoding. In this paper, we propose a model integration technique based on general factor dependent HMMs for decoding. The integrated HMMs can be used by a conventional decoder as standard triphone HMMs with Gaussian mixture densities. Moreover, by using the results of context clustering, the proposed method can determine an optimal number of mixture components for each state dependently of the degree of influence from additional factors. Phoneme recognition experiments using voice characteristic labels show significant improvements with a small number of model parameters, and a 19.3% error reduction was obtained in noise environment experiments.

This letter describes the polarization mode dispersion (PMD) characteristic of optical fiber ribbons inserted tightly into helical slots. We investigate the mechanism of the birefringence induced in the optical fiber ribbons by lateral stress resulting from tension and bending in the helical slots. We discuss methods for the design of low PMD cables with reduced birefringence by considering coating materials and tensile strain control.

We are developing a simple three-dimensional (3-D) display method that uses only two transparent images using luminance division displays without any extra equipment. This method can be applied to not only electronic displays but also the printed sheets. The method utilizes a 3-D visual illusion in which two ordinary images with many edges can be perceived as an apparent 3-D image with continuous depth between the two image planes, when two identical images are overlapped from the midpoint of the observer's eyes and their optical-density ratio is changed according to the desired image depths. We can use transparent printed sheets or transparent liquid crystal displays to display two overlapping transparent images using this 3-D display method. Subjective test results show that the perceived depths changed continuously as the optical-density ratio changed. Deviations of the perceived depths from the average for each observer were sufficiently small. The depths perceived by all six observers coincided well.

This paper investigates the parameter tying structures of a mixture of factor analyzers (MFA) and discriminative training of MFA for speaker identification. The parameters of factor loading matrices or diagonal matrices are shared in different mixtures of MFA. Then, minimum classification error (MCE) training is applied to the MFA parameters to enhance the discrimination ability. The result of a text-independent speaker identification experiment shows that MFA outperforms the conventional Gaussian mixture model (GMM) with diagonal or full covariance matrices and achieves the best performance when sharing the diagonal matrices, resulting in a relative gain of 26% over the GMM with diagonal covariance matrices. The improvement is more significant especially in sparse training data condition. The recognition performance is further improved by MCE training with an additional gain of 3% error reduction.