In this paper, we apply the discrete wavelet transform (DWT) and the discrete wavelet packet transform (DWPT) with the Daubechies wavelet of order 16 to effectively solve for the electromagnetic scattering from a one-dimensional inhomogeneous slab. Methods based on the excitation vector and the [Z] matrix are utilized to sparsify an MoM matrix. As we observed, there are no much high frequency components of the field in the dielectric region, hence the wavelet coefficients of the small scales components (high frequency components) are very small and negligible. This is different from the case of two-dimensional scattering from perfect conducting objects. In the excitation-vector-based method, a modified excitation vector is introduced to extract dominant terms and achieve a better compression ratio of the matrix. However, a smaller compression ratio and a tiny relative error are not obtained simultaneously owing to their deletion of interaction between different scales. Hence, it is inferior to the [Z]-matrix-based methods. For the [Z]-marix-based methods, our numerical results show the column-tree-based DWPT method is a better choice to sparsify the MoM matrix than DWT-based and other DWPT-based methods. The cost of a matrix-vector multiplication for the wavelet-domain sparse matrix is reduced by a factor of 10, compared with that of the original dense matrix.

We proposed a soft-decision decoding algorithm for cyclic codes based on energy minimization principle. This letter presents the algorithm which improves decoding performance and decoding complexity of the previous method by giving more initial positions and introducing a new criterion for terminating the decoding procedure. Computer simulation results show that both the decoded block error rate and the decoding complexity decrease by this method more than by the previous method.

Motivated by intention to evaluate asymptotically multiple-burst-error-correcting codes on channels with memory, we will derive the following fact. Let {Zi } be a hidden Markov process, i. e. , a functional of a Markov chain with a finite state space, and Wb(Z1Z2Zn) denote the number of burst errors that appear in Z1Z2Zn, where the number of burst errors is counted using Gabidulin's burst metric , 1971. As the main result, we will prove the almost sure convergence of relative burst weight Wb(Z1Z2Zn)/n, i. e. , the relative frequency of occurrence of burst errors, for a broad class of functionals { Zi } of finite Markov chains. Functionals of Markov chains are often adopted as models of the noises on channels, especially on burst-noise channels, the most famous model of which is probably the Gilbert channel proposed in 1960. Those channel models described with Markov chains are called channels with memory (including channels with zero-memory, i. e. , memoryless ones). This work's achievement enables us to extend Gilbert's code performance evaluation in 1952, a landmark that offered the well-known Gilbert bound, discussed its relationship to the (memoryless) binary symmetric channel, and has been serving as a guide for the-Hamming-metric-based design of error-correcting codes, to the case of the-burst-metric-based codes (burst-error-correcting codes) and discrete channels with or without memory.

Effective wavelets to solve electromagnetic integral equations are proposed. It is based on the same construction procedure as Daubechies wavelets but with mix-phase to obtain maximum sparsity of moment matrix. These new wavelets are proved to have excellent performance in non-zero elements reduction in comparison with minimum-phase wavelet transform (WT). If further sparsity is concerned, wavelet packet (WP) transform can be applied but increases the computational complexity. In some cases, the capability of non-zero elements reduction by this new wavelets even better than WP with minimum-phase wavelets and with less computational efforts. Numerical experiments demonstrate the validity and effectiveness of the new wavelets.

We investigated the relationship between the film characteristics and the sputtering rate of the MgO protecting layer in AC-PDP. As possible elements for determining the sputtering rate, we considered the density, orientation, and surface morphology. With respect to the orientation, we found that the sputtering rate increased for the sequence of (200) < (220) < (111). However, we noticed that orientation and surface structure are not really decisive factors affecting the sputtering rate; the density of the film is most important.

A partial buffer sharing scheme is proposed as loss-priority control for a finite buffer with batch Poisson inputs under a whole batch acceptance rule. Customer and batch loss probabilities for high- and low-priority customers are derived under this batch acceptance rule using a supplementary variable method. A comparison of the partial buffer sharing scheme and a system without loss-priority control is made in terms of admissible offered load. Whole batch acceptance and partial batch acceptance rules are also compared in terms of admissible offered load.

For the reduction of the jitter originated from the cell losses in ATM network when CBR traffic is transferred on AAL5, we propose that the receiver maintain a timer whose expiration time is proportional to the cell time of the source traffic plus the standard deviation of the 1-point CDV of the received ATM cells. Moreover, to enhance the granularity of the error or loss detection mechanism in the AAL5 PDUs, we also modified the AAL5 PDU trailer fields so that each cell comprising the AAL5 PDU has a sequence number field. The simulation results show that the peak-to-peak PDV of the AAL5 PDU by the proposed method is less than 69.4% to that by AAL5. Moreover, the AAL5 user receives the same or more error-free transport packets in the proposed algorithm than those in the ITU-T AAL5 for the same network simulation environment.

Clustering is almost essential in improving the performance of iterative partitioning algorithms. In this paper, we present a clustering algorithm based on the following observation: if a group of cells is assigned to the same partition in numerous local optimum solutions, it is desirable to merge the group into a cluster. The proposed algorithm finds such a group of cells from randomly generated local optimum solutions and merges it into a cluster. We implemented a multilevel bipartitioning algorithm (MBP) based on the proposed clustering algorithm. For MCNC benchmark netlists, MBP improves the total average cut size by 9% and the total best cut size by 3-4%, compared with the previous state-of-the-art partitioners.

In this paper, we consider the ring embedding problem in faulty star graphs. Our embedding is based on the path transition scheme and node borrow technique in the ring of 4-dimensional substars with evenly distributed faults. Let Sn be the n-dimensional star graph having n! nodes. We will show that a ring of length n! - 2f can be found in Sn when the number of faulty nodes f is at most n-3. In the worst case, the loss of 2f nodes in the size of fault-free ring is inevitable because the star graph is bipartite. In addition, this result is superior to the best previous result that constructs the ring of length n! - 4f under the same fault condition. Moreover, by extending this result into the star graph with both node and edge faults simultaneously, we can find the fault-free ring of length n! - 2 fn in Sn when it contains fn faulty nodes and fe faulty edges such that fn + fe n-3.

Shared buffer ATM switches have been attractive since they can achieve a superior performance in terms of cell loss ratio and throughput with a relatively small buffer size. Shared multi-buffer structures have also been considered by several researchers to enhance the access speed of the cell memory for a large switch. High quality services, however, cannot be provided without reliable operation at each module comprising the ATM switches. In this paper, we present a novel on-line error monitoring technique for shared-buffer ATM switches. The technique detects almost all of the functional errors that could occur in the ATM switches. Moreover, it can detect errors with small hardware overhead and negligible time overhead. An early detection of functional errors in ATM switches could not only reduce the wasted bandwidth due to the transmission of erroneous cells, but greatly enhance the recovery time.

Recent status of the polymer optical fiber (POF) for high speed data communication and telecommunication is reviewed. The GI POF was proposed for the first time 20 years ago at Keio University, and several methodologies to fabricate GI POF have been currently proposed worldwide. In this paper, we both theoretically and experimentally verify that the most transparent GI POF can be obtained by the polymer-dopant system. The relation between the refractive index profile and the dispersion characteristics of the GI POF was quantitatively clarified. The refractive index profile of the GI POF obtained by the interfacial-gel polymerization process was controlled to enable to transmit the order of gigabit per second bit rate. Furthermore, the accurate approximation of the refractive index profile and consideration of mode dependent attenuation enabled to precisely predict the dispersion characteristics of the GI POF.

This paper discusses global area optical transport ring networks using wavelength division multiplexing (WDM) technologies and proposes a novel optical add/drop multiplexer (OADM) architecture suitable for such an application field. Study on the requirements of a global area ring application elucidates the appropriate ring/protection architecture as the path switched bi-directional ring. The proposed OADM architecture has flexibility in terms of path provisioning and scalability. We conclude that the proposed OADM can effectively configure the large-scale path switched bi-directional rings.

Recent status of the polymer optical fiber (POF) for high speed data communication and telecommunication is reviewed. The GI POF was proposed for the first time 20 years ago at Keio University, and several methodologies to fabricate GI POF have been currently proposed worldwide. In this paper, we both theoretically and experimentally verify that the most transparent GI POF can be obtained by the polymer-dopant system. The relation between the refractive index profile and the dispersion characteristics of the GI POF was quantitatively clarified. The refractive index profile of the GI POF obtained by the interfacial-gel polymerization process was controlled to enable to transmit the order of gigabit per second bit rate. Furthermore, the accurate approximation of the refractive index profile and consideration of mode dependent attenuation enabled to precisely predict the dispersion characteristics of the GI POF.

In this paper, comparison of various orthogonal transforms in Wiener filtering is discussed. The study involves the family of discrete orthogonal transforms called Complex Hadamard Transform, which has been recently introduced by the same authors. Basic definitions, properties and transformation kernel of Complex Hadamard Transform are also shown.

This paper discusses global area optical transport ring networks using wavelength division multiplexing (WDM) technologies and proposes a novel optical add/drop multiplexer (OADM) architecture suitable for such an application field. Study on the requirements of a global area ring application elucidates the appropriate ring/protection architecture as the path switched bi-directional ring. The proposed OADM architecture has flexibility in terms of path provisioning and scalability. We conclude that the proposed OADM can effectively configure the large-scale path switched bi-directional rings.

A novel 1470-nm-band (S+ band) wavelength-division multiplexing (WDM) transmission system is described. The first advantage of S+-band transmission is suppression of degradation caused by four-wave mixing (FWM), which has been the dominant impairment factor in WDM transmission systems on dispersion-shifted fibers (DSFs). FWM suppression by using the S+ band instead of the conventional 1550-nm-band (M band) is successfully demonstrated. The second advantage is expansion of the usable bandwidth by using the S+ band together with other wavelength bands. A triple-wavelength-band WDM repeaterless transmission experiment using the S+ band, the M band and the L band (1580-nm-band) is conducted over DSF, and it is shown that degradation due to inter-wavelength-band nonlinear interactions is negligible in the transmission. Moreover, the transmission performance of an S+-band linear repeating system is estimated by computer simulation, and compared with that of other wavelength-band systems. In the experiments, thulium-doped fiber amplifiers (TDFAs) are used for amplification of signals in the S+ band.

A novel 1470-nm-band (S+ band) wavelength-division multiplexing (WDM) transmission system is described. The first advantage of S+-band transmission is suppression of degradation caused by four-wave mixing (FWM), which has been the dominant impairment factor in WDM transmission systems on dispersion-shifted fibers (DSFs). FWM suppression by using the S+ band instead of the conventional 1550-nm-band (M band) is successfully demonstrated. The second advantage is expansion of the usable bandwidth by using the S+ band together with other wavelength bands. A triple-wavelength-band WDM repeaterless transmission experiment using the S+ band, the M band and the L band (1580-nm-band) is conducted over DSF, and it is shown that degradation due to inter-wavelength-band nonlinear interactions is negligible in the transmission. Moreover, the transmission performance of an S+-band linear repeating system is estimated by computer simulation, and compared with that of other wavelength-band systems. In the experiments, thulium-doped fiber amplifiers (TDFAs) are used for amplification of signals in the S+ band.

Hierarchical macrocell/microcell architectures have been proposed for future cellular mobile communication. The performance analysis for the hierarchical cellular system becomes an important issue. In this paper, extending the analytical methods from[1][2][8], assuming that the imperfect power control follows log-normal statistics, and employing different attenuation models for macrocells and microcells, the capacity plane and outage probability of the system are examined and quantified with and without perfect sectorization. From the numerical results of parameters of IS-95 protocol, the high user capacity and lower outage probability may be expected in the case of relatively tight power control and narrower overlap between sectors. These results are compared with the previously published CDMA nonhierarchical cellular system estimation. When we employ the hierarchical cellular system, we can increase the user capacity 2.3 times with the same bandwidth 1.25 MHz than the one of the nonhierarchical cellular system.

The wavelet matrix transform approach, in combination with the method of moments (MoM), is applied to solve the electromagnetic scattering problem of an array of metal strips. The problem is first discretized by the conventional MoM to obtain a dense impedance matrix, then the wavelet matrix transform is applied to produce a sparse matrix. This approach avoids a great number of integral computations existing in the wavelet basis expansion method and provides fast approach to solution for the scattering problem. Daubechies' wavelet is chosen as the mother wavelet to construct a sparse wavelet matrix so that the matrix-matrix multiplications occurring in the transform cost only O(N2) with N unknowns. Numerical tests show that the computation cost necessary for solving the resultant sparse matrix is only O(N log N). An appropriate choice of the number of vanishing moments of wavelets is suggested from consideration of total computation cost and accuracy of solutions.

The onboard antenna beam forming network (BFN) of the next-generation communication satellites must offer multiple beam forming and beam steering. The conventional BFN, which directly controls the array elements, is not suitable for a large-scale array antenna because of the difficulty of BFN control. This paper proposes a new BFN configuration that consists of three/four-way variable power dividers and a Butler matrix (FFT circuit). This BFN can offer continuous beam steering with fewer variable components. By introducing new techniques based upon excluding FFT periods and power evaluations by definite integration, the deviation in beamwidth is reduced by 75% or more and the maximum sidelobe level is improved by 10 dB or more.