We presented a wall charge controlled ac PDP driving method which has advantages of less number of sub-fields and no dynamic false contours compared to the conventional driving method. In this method, a sub-field exhibited different light intensity according to the initial wall charge quantity set during the address period. Even though one can set 10 different wall charge states by changing the data pulse widths, we decided to define three states, 'on,' 'half-on,' and 'off.' By adding one state, the number of sub-field required to achieve 243 gray levels was reduced from 8 to 5. Furthermore, one can realize seven sub-fields, 255 gray level, complete stretched-out coding with which one can eliminate the dynamic false contours. Since this method can reduce number of sub-fields, it is suitable for higher resolution PDP's with more scan lines.

Recently, low-density parity-check (LDPC) codes have attracted much attention. LDPC codes can achieve the near Shannon limit performance like turbo codes. For the LDPC codes, the reduced complexity decoding algorithms referred to as uniformly most powerful (UMP) BP- and normalized BP-based algorithms were proposed for BPSK on an additive white Gaussian noise (AWGN) channel. The conventional BP and BP-based algorithms can be applied to BPSK modulation. For high bit-rate transmission, multilevel modulation is preferred. Thus, the BP algorithm for multilevel modulations is proposed in . In this paper, we propose the BP algorithm with reduced complexity for multilevel modulations, where the first likelihood of the proposed BP algorithm is modified to adjust multilevel modulations. We compare the error rate performance of the proposed algorithm with that of the conventional algorithm on AWGN and flat Rayleigh fading channels. We also propose the UMP BP- and normalized BP-based algorithms for multilevel modulations on AWGN and flat Rayleigh fading channels. We show that the error rate performance of the proposed BP algorithm is almost identical to that of the algorithm in, where the decoding complexity of the proposed BP algorithm is less than that of the algorithm in. We also show that the proposed BP-based algorithms can achieve the good trade-off between the complexity and the error rate performance.

The notion of k-wise independent permutations has several applications. From the practical point of view, it often suffices to consider almost (i.e., ε-approximate) k-wise independent permutation families rather than k-wise independent permutation families, however, we know little about how to construct families of ε-approximate k-wise independent permutations of small size. For any n > 0, let Sn be the set of all permutations on {0,1,..., n - 1}. In this paper, we investigate the size of families of ε-approximate k-wise independent permutations and show that (1) for any constant ε 0, if a family Sn of permutations is ε-approximate k-wise independent, then || n(n - 1) (n - k + 1) if ε< 1; || {n(n - 1) (n - k + 1)}/(1 +ε) otherwise; (2) for any constant 0< ε 1, there exists a family Sn of ε-approximate k-wise independent permutations such that || = ; (3) for any constant ε> 0 and any n = pm - 1 with p prime, it is possible to construct a polynomial time samplable family Sn of ε-approximate pairwise independent permutations such that || = O(n(n - 1)/ε); (4) for any constant ε> 0 and any n = pm with p prime, it is possible to construct a polynomial time samplable family Sn of ε-approximate 3-wise independent permutations such that || = O(n(n - 1)(n - 2)/ε). Our results are derived by combinatorial arguments, i.e., probabilistic methods and linear algebra methods.

This paper investigates some fundamental properties of one-way alternating pushdown automata with sublinear space. We first show that one-way nondeterministic pushdown automata are incomparale with one-way alternating pushdown automata with only universal states, for spaces between log log n and log n, and also for spaces between log n and n/log n. We then show that there exists an infinite space hierarchy among one-way alternating pushdown automata with only universal states which have sublinear space.

Finite-ground microstrip line (FGMSL) open-end discontinuities are characterized via a self-calibrated method of moments (MoM) as a unified circuit model with a fringing capacitance and radiation conductance. By integrating the short-open calibration (SOC) procedure into a determinant MoM, the model parameters are extracted without needing the alternative port impedance. Regardless of non-ideal voltage sources, extracted parameters are observed to achieve a stable convergence as the feeding line is sufficiently extended. After extracted capacitance of a FGMSL open-end with equal strip and finite-ground widths are validated against its traditional MSL counterpart with infinite ground, extensive results are given to originally demonstrate that the capacitance increases as a decelerated function of the finite-ground width and length while the conductance is negligibly small as compared with its imaginary part.

A CMOS DFE (decision feedback equalization) receiver with a clock-data skew compensation was implemented for the SSTL (stub-series terminated logic) SDRAM interface. The receiver consists of a 2 way interleaving DFE input buffer for ISI reduction and a X2 over-sampling phase detector for finding the optimum sampling clock position. The measurement results at 1.2 Gbps operation showed the increase of voltage margin by about 20% and the decrease of time jitter in the recovered sampling clock by about 40% by equalization in an SSTL channel with 2 pF 4 stub load. Active chip area and power consumption are 3001000 µm2 and 142 mW, respectively, with a 2.5 V, 0.25 µm CMOS process.

A variety of real-time multicast applications such as video conferences, remote lectures, and video-on-demand have become in commonplace with the expansion of broadband Internet services. Due to nontrivial problems in the IP multicast technology, the peer-to-peer multicast technology (P2P-multicast) has emerged as a practical implementation, although its network resource utilization is less efficient. A multihome network has the potential of alleviating this inefficiency by providing flexibility in communication path selections for each host with multiple gateways to the Internet. This paper has first formulated the P2P-multicast routing problem in the multihome network, and has proved the NP-completeness of its decision problem. Then, a two-stage heuristic algorithm called P2PMM_router has been presented for this P2P Multicast Multihome-network routing problem. The first stage constructs an initial multicast routing tree from an optimum spanning tree by Prim algorithm, through satisfying the constraints. The second stage improves the tree by repeating partial modifications and constraint satisfactions. The extensive simulation results using random network instances support the effectiveness of our P2PMM_router.

This paper addresses the problem of arranging fewest possible probes to detect a hidden object in a specified region and presents a reasonable scheme for the purpose. Of special interest is the case where an object is a double-sided conic cylinder which represents the shape of the energy distribution of laser light used in the optical network. The performance of our scheme is evaluated by comparing the number of probes to that of an existing scheme, and our scheme shows a potential for reducing the number of probes. In other words, the time for detection is significantly reduced from a realistic point of view.

The efficient squaring algorithm is an important role in large integer arithmetic. All multiplication algorithms can be used for squaring large integers, but their performance can be greatly improved by using the standard squaring algorithm. The standard squaring algorithm is quite well-known, but unfortunately there is an improper carry handling bug in it. Recently, Guajardo and Paar proposed a modified squaring algorithm to fix the bug in the standard squaring algorithm. In this paper, we first point out that there is still an error-indexing bug in the Guajardo-Paar squaring algorithm. Then, we propose a new efficient squaring algorithm that not only avoids the bugs in both the standard squaring algorithm and the Guajardo-Paar squaring algorithm but also improves the performance in squaring computation. Our analyses and our simulations indicate that the proposed squaring algorithm is about 2.5 times faster in comparison with the standard multiplication algorithm in Pentium Series CPU. The performance of 1024-bit RSA cryptosystem can be saved 34.3% by using the proposed squaring algorithm to replace the standard multiplication.

The issues of comparing the similarity or dissimilarity (distance) between structures have been studied. Especially, several distances between trees and their efficient algorithms have been proposed. However, all of the tree distances are defined based on mapping between vertices only, and they are helpless to compare the tree structures whose vertices and edges hold information. In this paper, we will propose a mapping between rooted and unordered trees based on vertex translation and edge translation, and then define a distance based on proposed mapping, and develop an efficient algorithm for computing proposed distance. Proposed distance can be used to compare the similarity or distance between two natural language sentences.

Support vector algorithms try to maximize the shortest distance between sample points and discrimination hyperplane. This paper suggests the total margin algorithms which consider the distance between all data points and the separating hyperplane. The method extends and modifies the existing algorithms. Experimental studies show that the total margin algorithms provide good performance comparing with the existing support vector algorithms.

In the CNN problem, a "scene" appears on the two-dimensional plane, at different positions sequentially, and a "camera crew" has to shoot the scene whenever it appears. If a scene appears at some position, the camera crew does not have to move to the position exactly, but has only to move to a point that lies in the same horizontal or vertical line with the scene. Namely it is enough to move either to the same row or to the same column. The goal is to minimize the total moving distance of the camera crew. This problem has been quite popular in the last decade but it is still open whether or not there is a competitive algorithm, i.e., an algorithm with competitive ratio bounded by a constant. In this paper we study this problem under a natural restriction that the server can move only along the X-axis and the Y-axis. It is shown that there exists a competitive algorithm for this restricted version, namely there is an online algorithm for this "axis-bound CNN" with competitive ratio 9.0.

This paper addresses problems involved in performing speech recognition over mobile and IP networks. The main problem is speech data loss caused by packet loss in the network. We present two missing-feature-based approaches that recover lost regions of speech data. These approaches are based on the reconstruction of missing frames or on marginal distributions. For comparison, we also use a packing method, which skips lost data. We evaluate these approaches with packet loss models, i.e., random loss and Gilbert loss models. The results show that the marginal-distributed-based technique is most effective for a packet loss environment; the degradation of word accuracy is only 5% when the packet loss rate is 30% and only 3% when mean burst loss length is 24 frames in the case of DSR front-end. The simple data imputation method is also effective in the case of clean speech.

Fractional calculus is the generalization of the operators of differential and integration to non-integer order, and a differential equation involving the fractional calculus operators such as d1/2/dt1/2 and d-1/2/dt-1/2 is called the fractional differential equation. They have many applications in science and engineering. But not only its analytical solutions exist only for a limited number of cases, but also, the numerical methods are difficult to solve. In this paper we propose a new numerical method based on the operational matrices of the orthogonal functions for solving the fractional calculus and fractional differential equations. Two classical fractional differential equation examples are included for demonstration. They show that the new approach is simper and more feasible than conventional methods. Advantages of the proposed method include (1) the computation is simple and computer oriented; (2) the scope of application is wide; and (3) the numerically unstable problem never occurs in our method.

A 2-dimensional cylindrical k-within-consecutive-(r, s)-out-of-(m, n):F system consists of m n components arranged on a cylindrical grid. Each of m circles has n components, and this system fails if and only if there exists a grid of size r s within which at least k components are failed. This system may be used into reliability models of "Feelers for measuring temperature on reaction chamber," "TFT Liquid Crystal Display system with 360 degree wide area" and others. In this paper, first, we propose an efficient algorithm for the reliability of a 2-dimensional cylindrical k-within-consecutive-(r, s)-out-of-(m, n):F system. The feature of this algorithm is calculating their system reliabilities with shorter computing time and smaller memory size than Akiba and Yamamoto. Next, we show some numerical examples so that our proposed algorithm is more effective than Akiba and Yamamoto for systems with large n.

In this paper, we formally define and analyze the security notions of authenticated encryption in unconditional security setting. For confidentiality, we define the notions, APS (almost perfect secrecy) and NM (non-malleability), in terms of an information-theoretic viewpoint along with our model where multiple senders and receivers exist. For authenticity, we define the notions, IntC (integrity of ciphertexts) and IntP (integrity of plaintexts), from a view point of information theory. And then we combine the above notions to define the security notions of unconditionally secure authenticated encryption. Then, we analyze relations among the security notions. In particular, it is shown that the strongest security notion is the combined notion of APS and IntC. Finally, we formally define and analyze the following generic composition methods in the unconditional security setting along with our model: Encrypt-and-Sign, Sign-then-Encrypt and Encrypt-then-Sign. Consequently, it is shown that: the Encrypt-and-Sign composition method is not always secure; the Sign-then-Encrypt composition method is not always secure; and the Encrypt-then-Sign composition method is always secure, if a given encryption meets APS and a given signature is secure.

We consider a new post-filtering algorithm for residual acoustic echo cancellation in hands-free application. The new post-filtering algorithm is composed of AR analysis, pitch prediction, and noise reduction algorithm. The residual acoustic echo is whitened via AR analysis and pitch prediction during no near-end talker period and then is cancelled by noise reduction algorithm. By removing speech characteristics of the residual acoustic echo, noise reduction algorithm reduces the power of the residual acoustic echo as well as the ambient noise. For the hands-free application in the moving car, the proposed system attenuated the interferences more than 15 dB at a constant speed of 80 km/h.

Hot spot service based on wireless LANs is expected to play an important role in the beyond 3G wireless networks. Although spatial coverage is very limited, a comfortable and higher speed compared with a cellular system is available there. However, there might exist nodes that cannot communicate directly with an Access Point (AP) because of the distant location or the shadowing due to obstacles. Accordingly, the introduction of two-hop relaying to the hot spot is useful to extend the coverage and avoid the dead spot. However, the throughput per node is getting decreased as the hot spot coverage area increases. Therefore, in this paper, we propose a scheme to reuse the same channel spatially wherever possible and apply it to the HiperLAN/2 based wireless LAN hot spot with two-hop relaying to compensate for the decrease of the throughput per node. Namely, we modify the HiperLAN/2 protocol in such a way that a time slot is reused at the nodes spatially separated far enough not to cause packet collision. Thus, the throughput is expected to be improved and confirmed by a theoretical analysis and computer simulations.

Future mobile communication systems are expected to support multimedia applications (audio phone, video on demand, video conference, file transfer, etc.). Multimedia applications make a great demand for bandwidth and impose stringent quality of service requirements on the mobile wireless networks. In order to provide mobile hosts with high quality of service in the next generation mobile multimedia wireless networks, efficient and better bandwidth reservation schemes must be developed. A novel traffic-based bandwidth reservation scheme is proposed in this paper as a solution to support quality of service guarantees in the mobile multimedia wireless networks. Based on the existing network conditions, the proposed scheme makes an adaptive decision for bandwidth reservation and call admission by employing fuzzy inference mechanism, timing based reservation strategy, and round-borrowing strategy in each base station. The amount of reserved bandwidth for each base station is dynamically adjusted, according to the on-line traffic information of each base station. We use the dynamically adaptive approach to reduce the connection-blocking probability and connection-dropping probability, while increasing the bandwidth utilization for quality of service sensitive mobile multimedia wireless networks. Simulation results show that our traffic-based bandwidth reservation scheme outperforms the previously known schemes in terms of connection-blocking probability, connection-dropping probability, and bandwidth utilization.

This paper describes an adaptive fingerprint-sensing scheme for a user authentication system with a fingerprint sensor LSI to obtain high-quality fingerprint images suitable for identification. The scheme is based on novel evaluation indexes of fingerprint-image quality and adjustable analog-to-digital (A/D) conversion. The scheme adjusts dynamically an A/D conversion range of the fingerprint sensor LSI while evaluating the image quality during real-time fingerprint-sensing operation. The evaluation indexes pertain to the contrast and the ridgelines of a fingerprint image. The A/D conversion range is adjusted by changing quantization resolution and offset. We developed a fingerprint sensor LSI and a user authentication system to evaluate the adaptive fingerprint-sensing scheme. The scheme obtained a fingerprint image suitable for identification and the system achieved an accurate identification rate with 0.36% of the false rejection rate (FRR) at 0.075% of the false acceptance rate (FAR). This confirms that the scheme is very effective in achieving accurate identification.