We demonstrate a single-channel 1.28 Tbit/s-525 km transmission using OTDM of subpicosecond DQPSK signals. In order to cope with transmission impairments due to time-varying higher-order PMD, which is one of the major limiting factors in such a long-haul ultrahigh-speed transmission, we newly developed an ultrafast time-domain optical Fourier transformation technique in a round-trip configuration. By applying this technique to subpicosecond pulses, transmission impairments were greatly reduced, and BER performance below FEC limit was obtained with increased system margin.

In this article, a simple structure of the Wilkinson power divider which can suppress the nth harmonics of the Wilkinson power divider is proposed. By replacing the quarter wavelength transmission lines of the conventional Wilkinson power divider with the equivalent P-type transmission lines, a compact power divider which can suppress the nth harmonic is achieved. Design equations of proposed P-type line are achieved by ABCD matrices. To verify the design approach, the proposed power divider is designed, simulated (by ADS, CST Studio, and Sonnet simulators), and fabricated at 1 GHz to suppress the fifth harmonic. The proposed structure is 46% of the conventional Wilkinson power divider, while maintaining the characteristics of the conventional Wilkinson power divider at the fundamental frequency. The insertion losses at the fifth harmonic are larger than 35 dB. Furthermore, the second to seventh harmonic are suppressed by least 10 dB. Here is an excellent agreement between simulated results and measured results.

In many real-world face recognition applications, there might be only one training image per person available. Moreover, the test images may vary in facial expressions and illuminations, or may be partially occluded. However, most classical face recognition techniques assume that multiple images per person are available for training, and they are difficult to deal with extreme expressions, illuminations and occlusions. This paper proposes a novel block-based bag of words (BBoW) method to solve those problems. In our approach, a face image is partitioned into multiple blocks, dense SIFT features are then calculated and vector quantized into different visual words on each block respectively. Finally, histograms of codeword distribution on each local block are concatenated to represent the face image. Our method is able to capture local features on each block while maintaining holistic spatial information of different facial components. Without any illumination compensation or image alignment processing, the proposed method achieves excellent face recognition results on AR and XM2VTS databases. Experimental results show that only using one neutral expression frame per person for training, our method can obtain the best performance ever on face images of AR database with extreme expressions, variant illuminations, and partial occlusions. We also test our method on the standard and darkened sets of XM2VTS database, and achieve the average rates of 100% and 96.10% on the standard and darkened sets of XM2VTS database, respectively.

In reconstruction-based super resolution, a high-resolution image is estimated using multiple low-resolution images with sub-pixel misalignments. Therefore, when only one low-resolution image is available, it is generally difficult to obtain a favorable image. This letter proposes a method for overcoming this difficulty for single- image super resolution. In our method, after interpolating pixel values at sub-pixel locations on a patch-by-patch basis by support vector regression, in which learning samples are collected within the given image based on local similarities, we solve the regularized reconstruction problem with a sufficient number of constraints. Evaluation experiments were performed for artificial and natural images, and the obtained high-resolution images indicate the high-frequency components favorably along with improved PSNRs.

The H.264/AVC standard achieves significantly high coding efficiency if multiple block size Motion Estimation is adopted. However, the complexity of Motion Estimation and DCT is dramatically increased as a result. In previous work we propose an early mode decision algorithm to control the complexity, based on all-zero-blocks detection in 1616 size. In this paper, we improve the algorithm. Firstly, we propose to detect all-zero blocks in 1616, 88 and 44 sizes to simplify the course of mode decision. Secondly, we define the thresholds which are used to terminate motion estimation and mode decision in advance for these sizes. Last, we present the whole proposed algorithm. Experiments show that about 77% encoding time and 85% motion estimation time can be saved on average, which is better than state-of-the-art approaches.

In this paper we show that the performance workload of button-input interfaces do not monotonically increase with the number of buttons, but there is an optimal number of buttons in the sense that the performance workload is minimized. As the number of buttons increases, it becomes more difficult to search for the target button, and, as such, the user's cognitive workload is increased. As the number of buttons decreases, the user's cognitive workload decreases but his operational workload increases, i.e., the amount of operations becomes larger because one button has to be used for plural functions. The optimal number of buttons emerges by combining the cognitive and operational workloads. The experiments used to measure performance were such that we were able to describe a multiple regression equation using two observable variables related to the cognitive and operational workloads. As a result, our equation explained the data well and the optimal number of buttons was found to be about 8, similar to the number adopted by commercial cell phone manufacturers. It was clarified that an interface with a number of buttons close to the number of letters in the alphabet was not necessarily easy to use.

This paper proposes a low-complexity algorithm to calculate log likelihood ratios (LLRs) of coded bits, which is necessary for channel decoding in coded MIMO mobile communications. An approximate LLR needs to find a pair of transmitted signal candidates that can maximize the log likelihood function under a constraint that a coded bit is equal to either one or zero. The proposed algorithm can find such a pair simultaneously, whereas conventional ones find them individually. Specifically, the proposed method searches for such candidates in directions of the noise enhancement using the MMSE detection as a starting point. First, an inverse matrix which the MMSE weight matrix includes is obtained and then the power method derives eigenvectors of the inverse matrix as the directions of the noise enhancement. With some eigenvectors, one-dimensional search and hard decision are performed. From the resultant signals, the transmitted signal candidates to be required are selected on the basis of the log likelihood function. Computer simulations with 44 MIMO-OFDM, 16QAM, and convolutional codes (rate =1/2, 2/3) demonstrate that the proposed algorithm requires only 1.0 dB more Eb/N0 than that of the maximum likelihood detection (MLD) in order to achieve packet error rate of 10-3, while reducing the complexity to about 0.2% of that of MLD.

In this paper, we introduce a new general construction of zero correlation zone (ZCZ) sequence set, which is based on two given ZCZ sequence sets. Compared with the two given sequence sets, the resultant sequence set not only has larger family size and longer period, but also provides more flexible choices of basic sequences, ZCZ length and family size.

A two-dimensional filter for photonic label recognition system using time-to-space conversion and delay compensation was designed using Genetic-Algorithms (GA). For four-bit Binary Phase Shift Keying (BPSK) labels at 160 Gbit/s, contrast ratio of the output for eight different labels was improved by optimization of two-dimentional filtering. The contrast ratio of auto-correlation to cross-correlation larger than 2.16 was obtained by computer simulation. This value is 22% larger than the value of 1.77 with the previously reported system using matched filters.

In this paper we unveil basic properties of a code Γq for digital fingerprinting based on a projective plane of order q. We consider a situation where a coalition of malicious users generates a pirated digital content in which a binary sequence w is embedded subject to the marking assumption. Here, the size of the coalition is assumed to be less than or equal to a known constant c ≥ 2. We evaluate the number of candidates of the coalition that can also generate w subject to the marking assumption. It is shown that the number of such candidates is completely determined as a function of w for the case of c = 2. In addition, we give a sufficient condition under which all the malicious users are correctly identified from w for the case of c ≥ 3. Relationships between Γq and other existing classes of codes are discussed as well.

An asymptotic expansion of the amplitude of the scattered wave by an imperfection core in a waveguide system is derived and it is shown that the scattered wave is partially canceled by the direct wave at large distance and a shadow takes place. For z→ ∞ where z is the distance along the waveguide axis the amplitudes of the direct and scattered waves decrease in proportion to z- and in the shadow region the amplitude of the sum of both waves decreases in proportion to z-. To supplement the analytical results some numerical examples are shown.

In this letter, we propose a new observer error linearization approach that is called reduced-order dynamic observer error linearization (RDOEL), which is a modified version of dynamic observer error linearization (DOEL). We introduce the concepts and properties of RDOEL, and provide a complete solution to RDOEL with one integrator. Moreover, we show that it is also a complete solution to a simple case of DOEL.

An improvement of estimating sound power spectra located in a particular 2-dimensional area is proposed. We previously proposed a conventional method that estimates sound power spectra using multiple fixed beamformings in order to emphasize speech located in a particular 2-dimensional area. However, the method has one drawback that the number of areas where the active sound sources are located must be restricted. This restriction makes the method less effective when many noise source located in different areas are simultaneously active. In this paper, we reveal the cause of this restriction and determine the maximum number of areas for which the method is able to simultaneously estimate sound power spectra. Then we also introduce a procedure for investigating areas that include active sound sources to reduce the number of unknown power spectra to be estimated. The effectiveness of the proposed method is examined by experimental evaluation applied to sounds recorded in a practical environment.

It is necessary to perform arithmetic in Fp12 to use an Ate pairing on a Barreto-Naehrig (BN) curve, where p is a prime given by p(z)=36z4+36z3+24z2+6z+1 for some integer z. In many implementations of Ate pairings, Fp12 has been regarded as a 6th degree extension of Fp2, and it has been constructed by Fp12=Fp2[v]/(v6-ξ) for an element ξ ∈ Fp2 such that v6-ξ is irreducible in Fp2[v]. Such a ξ depends on the value of p, and we may use a mathematical software package to find ξ. In this paper it is shown that when z ≡ 7,11 (mod 12), we can universally construct Fp12 as Fp12=Fp2[v]/(v6-u-1), where Fp2=Fp[u]/(u2+1).

Those host-based intrusion detection models like VPStatic first construct a model of acceptable behaviors for each monitored program via static analysis, and then perform intrusion detection by comparing them with programs' runtime behaviors. These models usually share the highly desirable feature that they do not produce false alarms but face the conflicts between accuracy and efficiency. For instance, the high accuracy of the VPStatic model is at the cost of high space complexity. In this paper, we use a statically-constructed state transition table (STT), which records expected transitions among system calls as well as their stack states (return address lists), as a behavior model to perform context-sensitive intrusion detection. According to our analysis, our STT model improves the space efficiency of the VPStatic model without decreasing its high precision and time efficiency. Experiments show that for three test programs, memory uses of our STT models are all much less than half of the VPStatic models'. Thereby, we alleviate the conflicts between the accuracy and the efficiency.

As old as TANDEM-DM, the compression function ABREAST-DM is one of the most well-known constructions for double block length compression functions. In this paper, we give a security proof for ABREAST-DM in terms of collision resistance and preimage resistance. The bounds on the number of queries for collision resistance and preimage resistance are given by Ω(2n). Based on a novel technique using query-response cycles, our security proof is simpler than those for MDC-2 and TANDEM-DM. We also present a wide class of ABREAST-DM variants that enjoy a birthday-type security guarantee with a simple proof*.

The effect of DC offset on multi-input multi-output (MIMO) direct transceivers with adaptive modulation (AM) is discussed in this paper. A variable-rate variable-power (VRVP) AM system with perfect channel state information (P-CSI) at both the transmitter and receiver in a MIMO scenario is considered. The DC offset is modeled as a zero mean complex Gaussian distributed random variable. By this modeling of the DC offset, the analytical expression for degraded bit error rate (BER) is derived. To derive this analytical expression, we establish a reasonable approximation. The good agreement between the analytical and simulation results shows that the approximation is valid and confirms the accuracy of the analytical expressions. Moreover, an approach to improve the degraded BER in these systems is introduced. For this purpose, we introduce a design for AM MIMO systems that takes account of DC offset and its effectiveness is confirmed. Throughput analysis for the AM MIMO system in the presence of DC offset is presented in this paper too. An analytical expression for throughput is derived and approximated to a simpler equation. At last, throughput results are compared to the simulation outcomes.

This paper presents a formulation of two-dimensional photonic crystal waveguide devices formed by circular cylinders. The device structures are considered as cascade connections of straight waveguides. Decomposing the structure into layers of the cylinder arrays, the input/output properties of the devices are obtained using an analysis method of multilayer structure. We introduce periodic boundary conditions in the direction perpendicular to the wave propagation, and the Floquet-modes of each layer are calculated by the Fourier series expansion method with the help of the recursive transition-matrix algorithm. Then, the input/output properties of the devices are obtained by recursive calculation of scattering matrix with each layer. The presented formulation is validated by numerical experiments by comparing with the previous works.

In UWB systems, data symbols are transmitted and received continuously. The Fast Fourier Transform (FFT) processor must be able to seamlessly process input/output data. This paper presents the design and implementation of a continuous data flow parallel memory-based FFT (CF-PMBFFT) processor without the use of input buffer for pre-loading the input data. The processor realizes a memory space of two N-words and multiple processing elements (PEs) to achieve the seamless data flow and meet the design requirement. The circuit has been fabricated in TSMC 0.18 µm 1P6M CMOS process with the supply voltage of 1.8 V. Measurement results of the test chip shows that the developed CF-PMBFFT processor takes a core area of 1.97 mm2 with a power consumption of 62.12 mW for a throughput rate of 528 MS/s.

A novel computational method is proposed to investigate electromagnetic scattering problems. It is error controllable and reliable simulation in time domain can be performed. We apply the proposed method to analysis of transient scattering from open-ended structures and discuss scattering mechanisms.