A novel high temperature superconducting interdigital bandpass filter is proposed by using coplanar waveguide quarter-wavelength resonators. The CPW resonators are arranged in parallel, and consequently the filter becomes very compact. The filter is a 5-pole Chebyshev BPF with a midband frequency of 5.0 GHz and an equal-ripple fractional bandwidth of 3.2%. It is fabricated using a YBCO film deposited on an MgO substrate. The measured filtering characteristics agree well with EM simulations and show a low insertion loss in spite of the small size of the filter.

An FRPA (frequency reuse power allocation) technique by employing the frequency reuse notion as a strategy for overcoming the ICI (intercell interference) and maintaining the QoS (quality of service) at the cell boundary is described for broadband cellular networks. In the scheme, the total bandwidth is divided into sub-bands and two different power levels are then allocated to sub-bands based on the frequency reuse for forward-link cell planning. In order to prove the effectiveness of the proposed algorithm, a Monte Carlo simulation was performed based on the Chernoff upper bound. The simulation shows that this technique can achieve a high channel throughput while maintaining the required QoS at the cell boundary.

The performance of a feedback-type adaptive array antenna (AAA) system placed only at a base station (BS) in an FDD/DS-CDMA system remains insufficiently clear. We evaluate the performance of this system by considering the effect of a rake receiver, spacing distance between antennas, the maximum Doppler frequency (fd), and control delay time (Td) on BER performance. In this system, the mobile station (MS) determines optimum weights of antenna elements and sends them back to BS as feedback information. We assume that the optimum weights are not quantized. Thereby, we estimate the performance degradation of 3GPP transmit diversity system, where the feedback information is quantized using a few bits. Computer simulation results show that the rake receiver achieves better BER performance because of the time diversity effect with rake receiver. The AAA with a wide antenna spacing gives high diversity gain for the received signals. For a high value of fd Td, BER performance becomes worse because weighting factors cannot follow the changing speed of channel characteristics. The degradation in performance of a 3GPP system is clarified.

The 2-terminal shortest path problem is to find a shortest path between two specified vertices in a given graph G. In this paper, we consider this problem in the following situation: G is given before the two vertices are specified so that some preprocessing is allowed to reduce the response time. We present a method for calculating lower bounds of the length of the shortest path for any pair of vertices. Experimental results show that the A* algorithm with our method performs much better than previous methods.

This paper proposes a new approach for analog portion testing, which can meet requirements for high-speed and high-accuracy testing simultaneously with reasonable cost. The key concept of the new method is cooperation of an LSI tester and some circuitry built in a target SoC device. We will explain the operation principle of the proposed method. The proposed method can be one of the methods to overcome today's expensive production test of analog portion on SoC (System on Chip) devices which heavily depends on LSI tester capability and will become harder in near future.

This paper discusses the least-squares linear filtering and smoothing (fixed-point and fixed-interval) problems of discrete-time signals from observations, perturbed by additive white noise, which can be randomly delayed by one sampling time. It is assumed that the Bernoulli random variables characterizing delay measurements are correlated in consecutive time instants. The marginal distribution of each of these variables, specified by the probability of a delay in the measurement, as well as their correlation function, are known. Using an innovation approach, the filtering, fixed-point and fixed-interval smoothing recursive algorithms are obtained without requiring the state-space model generating the signal; they use only the covariance functions of the signal and the noise, the delay probabilities and the correlation function of the Bernoulli variables. The algorithms are applied to a particular transmission model with stand-by sensors for the immediate replacement of a failed unit.

This paper presents a new generative approach for generating two-dimensional signals having both a low peak factor (crest factor) and a flat power spectrum. The flat power spectrum provides zero auto-correlation, except at the zero shift. The proposed method is a generative scheme, not a search method, and produces a two-dimensional signal of size 2(2n1+1)2(2n2+1)2 for an arbitrary pair of positive integers n1 and n2 without any computer search. The peak factor of the proposed signal is equal to the peak factor of a single trigonometric function.

This paper introduces a State Dependent Random Early Detection (SDRED) scheme that can improve delay and jitter performances by adjusting RED parameters such as maxth and wq according to queue status. The SDRED is designed to adapt to traffic conditions by adjusting the maximum threshold and queue weight to four different levels. From the simulation results, we show that the SDRED decreases queuing delay and has more stable jitter characteristics than the existing RED, BLUE, ARED and DSRED schemes.

This paper presents a way of using a linear regression model to produce a single-valued criterion that indicates the perceived importance of each block in a stream of speech blocks. This method is superior to the conventional approach, voice activity detection (VAD), in that it provides a dynamically changing priority value for speech segments with finer granularity. The approach can be used in conjunction with scalable speech coding techniques in the context of IP QoS services to achieve a flexible form of quality control for speech transmission. A simple linear regression model is used to estimate a mean opinion score (MOS) of the various cases of missing speech segments. The estimated MOS is a continuous value that can be mapped to priority levels with arbitrary granularity. Through subjective evaluation, we show the validity of the calculated priority values.

The 2-vertex-connectivity augmentation problem for a specified set of vertices of a graph with degree constraints, 2VCA-SV-DC, is defined as follows: "Given an undirected graph G = (V,E), a specified set of vertices S ⊆V with |S|3 and a function g:V→Z+∪{∞}, find a smallest set E' of edges such that (V,E ∪E') has at least two internally-disjoint paths between any pair of vertices in S and such that vertex-degree increase of each v ∈V by the addition of E' to G is at most g(v), where Z+ is the set of nonnegative integers." This paper shows a linear time algorithm for 2VCA-SV-DC.

By applying the differential space-time block code (DSTBC) to wireless multicarrier transmission, Diggavi et al. were the first to propose the two-input-multiple-output (2IMO) differentially space-time-time block coded OFDM (TT-OFDM) system. In this paper, we propose three novel differentially transmit-diversity block coded OFDM (DTDBC-OFDM) systems, namely, the FT-, FF-, and TF-OFDM systems. For instance, the TF-OFDM stands for the differentially space-time-frequency block coded OFDM. Moreover, the noncoherent maximum-likelihood sequence detector (NSD), and its three special cases, namely, the noncoherent one-shot detector, the linearly predictive decision-feedback (DF) detector, and the linearly predictive Viterbi receiver are incorporated to the 2IMO DTDBC-OFDM systems. Furthermore, a simple closed-form BER expression for the systems utilizing the noncoherent one-shot detector in the time-varying multipath Rayleigh fading channels is given. Numerical results have revealed that 2IMO DTDBC-OFDM systems employing the noncoherent one-shot detector can obtain significant performance improvement. However, when few antennas are available, the implementation of the linearly predictive DF detector or the linearly predictive Viterbi receiver is necessary for achieving better performance.

The present paper introduces an improved construction of a class of binary sequences having a zero-correlation zone (hereafter binary ZCZ sequence set). The cross-correlation function and the side-lobe of the auto-correlation function of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. The present paper shows that such a construction generates a binary ZCZ sequence set from an arbitrary M-sequence. The previously reported sequence construction of binary ZCZ sequence sets from an M-sequence can generate a single series of binary ZCZ sequence sets from an M-sequence. The present paper proposes an improved sequence construction that can generate more than one series of binary ZCZ sequence sets from an M-sequence.

iPat/OMP is an interactive parallelization assistance tool for OpenMP. In the present paper, we describe the design concept of iPat/OMP, the parallelization sequence achieved by the tool and its current implementation status. In addition, we present an evaluation of the performance of the implemented functionalities. The experimental results show that iPat/OMP can detect parallelism and create an appropriate OpenMP directive for several for-loops.

A network for the detection of an approaching object with simple-shape recognition is proposed based on lower animal vision. The locust can detect an approaching object through a simple process in the descending contralateral movement detector (DCMD) in the locust brain, by which the approach velocity and direction of the object is determined. The frog can recognize simple shapes through a simple process in the tectum and thalamus in the frog brain. The proposed network is constructed of simple analog complementary metal oxide semiconductor (CMOS) circuits. The integrated circuit of the proposed network is fabricated with the 1.2 µm CMOS process. Measured results for the proposed circuit indicate that the approach velocity and direction of an object can be detected by the output current of the analog circuit based on the DCMD response. The shape of moving objects having simple shapes, such as circles, squares, triangles and rectangles, was recognized using the proposed frog-visual-system-based circuit.

In this paper, we present Blueweb, a new Bluetooth-based multihop network with an efficient scatternet formation algorithm and a hybrid routing protocol. The Blueweb is designed from the original idea of Bluetree. Blueweb's scatternet formation uses two mechanisms. One is the role exchange mechanism in which only slave nodes serve as the role of relay through the whole scatternet. The other one is the return connection mechanism in which we convert the scatternet from a tree-shaped to a web-shaped topology. Meanwhile, a modified source routing protocol is designed for Blueweb in which we combine the proactive method with the reactive method to discover the optimal path for packet transmission. Furthermore, using computer simulations we compared the system performance of Blueweb and Bluetree with both a static model and a uniform traffic model. With the static model we evaluate the scatternet performance and with the uniform traffic model we evaluate the transmission performance. Our simulation results show that Blueweb achieves superior system performance than Bluetree on both scatternet performance and transmission performance.

Seamless interconnection with wireless LAN and 3G technologies is essential for the future wireless environment. The Wireless Local Area Network (WLAN) integrated mobile device is designed to extend the reach of enterprise applications and to create new collaboration environments. Also rapid new service development has started to change traffic mixes in the cellular networks towards IP dominating carriers like GPRS (General Packet Radio Service) and WLAN. These drastic changes require new research in the network as well as system inter-working areas for both the cellular and WLAN technology areas. This is the main challenge our research is trying to solve giving answers to rising inter-working and interoperability questions.

Grid computing presents a new trend to distributed and Internet computing to coordinate large scale resources sharing and problem solving in dynamic, multi-institutional virtual organizations. Due to the diverse failures and error conditions in the grid environments, developing, deploying, and executing applications over the grid is a challenge, thus dependability is a key factor for grid computing. This paper presents a dependable grid computing framework, called DRIC, to provide an adaptive failure detection service and a policy-based failure handling mechanism. The failure detection service in DRIC is adaptive to users' QoS requirements and system conditions, and the failure-handling mechanism can be set optimized based on decision-making method by a policy engine. The performance evaluation results show that this framework is scalable, high efficiency and low overhead.

In this paper, routing properties of cube-based optoelectronic OTIS networks are explored. We show emulations of various cubical network topologies on their OTIS augmented variants, including the n-D grid networks, shuffle-exchange, and de Brujin networks. An analytical performance model for OTIS-cube networks is proposed. The model is validated by means of comparison with rigorously obtained simulation results. Using this model, the performance characteristics of the OTIS-hypercube network are evaluated in view of a number of different constraints. Moreover, we compare the performance characteristics of the OTIS-hypercube with that of equivalent fully-electronic networks under various implementation constraints.

We report on the design and experimental results of a fix-tuned Superconductor-Insulator-Superconductor (SIS) mixer for Atacama Large Millimeter/submillimeter Array (ALMA) band 8 (385-500 GHz) receivers. Nb-based SIS junctions of a current density of 10 kA/cm2 and one micrometer size (fabricated with a two-step lift-off process) are employed to accomplish the ALMA receiver specification, which requires wide frequency coverage as well as low noise temperature. A parallel-connected twin-junction (PCTJ) is designed to resonate at the band center to tune out the junction geometric capacitance. A waveguide-microstrip probe is optimized to have nearly frequency-independent impedance at the probe's feed point, thereby making it easy to match the low-impedance PCTJ over a wide frequency band. The RF embedding impedance is retrieved by fitting the measured pumped I-V curves to confirm good matching between PCTJ and signal source. We demonstrate here a minimum double-sideband receiver noise temperature of 3 times of quantum limits for an intermediate-frequency range of 4-8 GHz. The mixers were measured in band 8 cartridge with a sideband separation scheme. Single-sideband receiver noise below ALMA specification was achieved over the whole band.

This paper describes a numerical design procedure of element values of RC polyphase filters with equal minima in stopband and equal ripple in passband. Determination of element values of RC polyphase filters with equal-ripple characteristic have not been solved to the best knowledge of the authors. There found a paper tackling with the problem; however, it can only give sub-optimal solutions via numerical calculation [3]. We propose a numerical element value design procedure for RC polyphase filters with equi-ripple gain in both stopband and passband by using the coefficient matching method. Some design examples are given.