Implementation of Multi-Input Multi-Output (MIMO) channel sounder is considered, taking hardware cost and realtime measurement into account. A remarkable difference between MIMO and conventional Single-Input Multi-Output (SIMO) channel sounding is that the MIMO sounder needs some kind of multiplexing to distinguish transmitting antennas. We compared three types of multiplexing TDM, FDM, and CDM for the sounding purpose, then we chose FDM based technique to achieve cost effectiveness and realtime measurement. In the framework of FDM, we have proposed an algorithm to estimate MIMO channel parameters. Furthermore the proposed algorithm was implemented into the hardware, and the validity of the proposed algorithm was evaluated through measurements in an anechoic chamber.

A rapid Pseudo-Noise (PN) acquisition scheme is proposed. The proposed scheme consists of a phase alignment detector and Voltage Controlled Clock (VCC) loop. The VCC loop is used to control the phase update of the local PN signal. It has an auxiliary signal that provides the loop with two stable locking points as well as the direction of each phase update. The performance of the proposed scheme is evaluated by simulation. Results show that the proposed scheme acquires the phase two to three times faster than the conventional coherent serial scheme, and 1.5 times faster than of that in [10], at a small amount of additional hardware.

As a center of mobile multimedia of the 21st century, it is very much looking forward to explosion of R&D and business of the next generation of mobile communication systems and the ITS (Intelligent Transport Systems) because ITS will enable information-oriented in the field of the road, traffic and vehicles, by using the most advanced technologies of mobile communications and devices, for the various purposes such as decrease of the traffic accident, the reduction of traffic jam, the increase in efficiency of the logistics and the harmony with the earth environment. This invited paper will first briefly introduce evolution of mobile communications and ITS in ministries, industries and academia in Japan. Then core communication technologies for ITS will be overviewed such as spread spectrum CDMA, adaptive antenna array, and software radio or software defined radio. Demands of SoC (System on a Chip) to carry out the core technologies will be addressed.

In the field of computer graphics (CG), some adaptive methods have been proposed in order to make CG images more real in relatively low computational cost. As one of such adaptive methods, in this paper, an adaptive method will be proposed for detection of edges and approximation of surfaces in the use of the so-called automatic differentiation. In the proposed method a CG image with high quality can be generated in suitable computational cost. In this paper, three cases will be considered. The first is an adaptive distributed ray tracing which can adaptively generate anti-aliased CG images in suitable computational cost. The second is a high quality triangular meshing, which guarantees accuracy of the generated meshes according to shape of given surface in suitable computational cost. The last case is used in the so-called radiosity method.

The constant-Q based wavelet transform is the most effective means of quantitatively characterizing high frequency transient signals. This study develops a novel non constant-Q based multi-resolution transform (NCQM) and provides a precision analysis descriptor for both low and high frequency transients. The properties of this novel NCQM kernel are thoroughly examined and then the striking conceptual resemblance, energy conservation characteristic, and power spectrum close forms are derived. The rapid algorithm of NCQM is also presented and its excellent performance in noisy environments is demonstrated.

This letter proposes a 3-D stereo endoscopic image processing system. Whereas a conventional 3-D stereo endoscopic system has simple monitoring functions, the proposed system gives doctors exact depth feelings by providing them depth value information, visualization, and stereo PACS viewer to aid an education, accurate diagnosis, a surgical operation, and to further apply in a robotic surgery.

A number of studies have recently been published concerning chaotic neuron models and asynchronous neural networks having chaotic neuron models. In the case of large-scale neural networks having chaotic neuron models, the neural network should be constructed using analog hardware, rather than by computer simulation via software, due to the high speed and high integration of analog circuits. In the present study, we discuss the circuit structure of a chaotic neuron model, which is constructed on the basis of the mathematical model of an asynchronous chaotic neuron. We show that the pulse-type hardware chaotic neuron model can be constructed on the basis of the mathematical model of an asynchronous chaotic neuron. The proposed model is an effective model for the cell body section of the pulse-type hardware chaotic neuron model for ICs. In addition, we show the bifurcation structure of our composed model, and discuss the bifurcation routes and return maps thereof.

A near-optimum parallel algorithm for bipartite subgraph problem using gradient ascent learning algorithm of the Hopfield neural networks is presented. This parallel algorithm, uses the Hopfield neural network updating to get a near-maximum bipartite subgraph and then performs gradient ascent learning on the Hopfield network to help the network escape from the state of the near-maximum bipartite subgraph until the state of the maximum bipartite subgraph or better one is obtained. A large number of instances have been simulated to verify the proposed algorithm, with the simulation result showing that our algorithm finds the solution quality is superior to that of best existing parallel algorithm. We also test the proposed algorithm on maximum cut problem. The simulation results also show the effectiveness of this algorithm.

This paper proposes a novel method to realize an input stage for a rail-to-rail operational transconductance amplifier (OTA). The proposed input stage consists of single channel type MOSFETs. Therefore no matching is necessary between n-channel MOSFETs and p-channel MOSFETs unlike conventional methods. The proposed input stage is composed of three MOSFETs which operate in plural operation regions. Nevertheless a combination of drain currents of the three MOSFETs is proportional to an input voltage which varies between two power-supply rails. A circuit configuration to realize a rail-to-rail OTA with the proposed input stage is also proposed. The operation principle and the validity of the proposed circuit are confirmed through HSPICE simulations.

We present a state-space approach to the problem of designing a parallel feedforward compensator (PFC), which has the same dimension of the input i.e. input-dimensional, for a class of non-square linear systems such that the closed-loop system is strictly passive. For a non-minimum phase system or a system with high relative degree, passification of the system cannot be achieved by any other methodologies except by using a PFC. In our scheme, we first determine a squaring gain matrix and an additional dynamics that is connected to the system in a feedforward way, then a static passifying control law is designed. Consequently, the actual feedback controller will be the static control law combined with the feedforward dynamics. Necessary and sufficient conditions for the existence of the PFC are given by the static output feedback formulation, which enables to utilize linear matrix inequality (LMI). Since the proposed PFC is input-dimensional, our design procedure can be viewed as a solution to the low-order dynamic output feedback control problem in the literature. The effectiveness of the proposed method is illustrated by some numerical examples.

Existing byte error control codes require too many check bits if applied to a memory system that uses recent semiconductor memory chips with wide I/O data such as 16 or 32 bits, i.e., b=16 or 32. On the other hand, semiconductor memory chips are highly vulnerable to random double bit within a memory chip errors when they are used in some applications, such as satellite memory systems. Under this situation, it becomes necessary to design suitable new codes with double bit within a chip error correcting capability for computer memory systems. This correspondence proposes a class of codes called Double bit within a block Error Correcting - Single b-bit byte Error Correcting ((DEC)B-SbEC) codes where block and byte correspond to memory chip and memory sub-array data outputs, respectively. The proposed codes provide protection from both random double bit errors and single sub-array data faults. For most of the practical cases, the (DEC)B-SbEC codes presented in this correspondence have the capability of accommodating the check bits in a single dedicated memory chip.

In this letter, sampling and quantizer design for the Gaussian detection problem are considered. A constraint on the transmission rate from the remote sensor to the optimal discrete detector is assumed. The trade-off between sampling rate and the number of quantization levels is studied and illustrated by means of an example.

Methodologies for more efficient Raman amplification and a more suitable modulation format for 40 Gbit/s WDM unrepeatered transmission are investigated. Management of the fiber effective area is proposed to realize low noise distributed Raman amplification. An Aeff management technique in which low-Aeff fiber is located in a median section instead of the last section, was confirmed numerically and experimentally to improve the OSNR and Q-factor. Carrier-suppressed-return-to-zero (CS-RZ) modulation has the advantage of reducing fiber-nonlinearity effects and permitting denser multiplexing of the wavelengths. 40 Gbit/s 32-channel unrepeatered WDM transmission over 202 km was demonstrated employing the proposed methodologies.

A 1.6-Tb/s dense WDM signal was successfully transmitted over 480 km using the carrier-suppressed return-to-zero (CS-RZ) modulation format. The CS-RZ format was chosen because it exhibited better transmission performance over a wide fiber-input power window than the NRZ and RZ formats in a 40-Gb/s-based WDM transmission experiment with 100-GHz channel spacing, confirming its nonlinearity-insensitive nature in dense WDM systems. With the wide power window of CS-RZ, we achieved stable transmission of 4040-Gb/s WDM signals over a 480-km (680 km) standard SMF line with only the C-band, in which a spectral ripple remained during transmission. Distributed Raman amplification and forward error correction were not used, providing a margin for already installed transmission lines.

In this paper, we propose a method of unicast and broadcast packet sharing for the orthogonal frequency division multiplexing (OFDM) multi-base station (BS) indoor wireless communication system using an adaptive array antenna on mobile terminals. The adaptive array antenna placed on the mobile terminal allows quality improvement due to the diversity effect when the data transmitted from all BSs are the same, and provides capacity improvement by channel sharing when the data from each BS are different. In the proposed sharing method, unicast packets are transmitted independently from multiple BSs in order to increase the communication capacity, and broadcast packets are transmitted simultaneously with other BSs in order to enhance the communication quality without retransmission. Furthermore, by modifying the packet assignment procedure, we confirm that quality can be improved for unicast packets in a low traffic environment.

In this paper, we propose an activity-based estimation scheme to determine the received signal power disparity, that enhances the BER performance of the SIC scheme in a DS/CDMA system considering a practical voice activity factor, and compare BER performance with those of other schemes with or without estimation. Numerical analysis results show that the SIC scheme with the proposed activity-based estimation improves the BER performance compared with that without considering voice activity, and it approaches to that of the ideal estimation as the total number of concurrent users increases. In addition, the higher becomes the maximum attainable SNR, the better becomes the BER performance of the proposed activity-based estimation scheme.

This paper presents a high quality 4-kbit/s speech coding algorithm based on a CELP algorithm. The coder operates on speech frames of 20 ms. The algorithm has following four main features: multiple sub-codebooks, backward adaptive mode switching, dispersed-pulse structure, and noise post-processing. The multiple sub-codebooks consist of a pulse-codebook and a random-codebook so that they can handle both signals, noise-like (e.g. unvoiced, stationary noise) and pulse-like (e.g. voiced). The backward adaptive mode switching is performed using decoded parameters; therefore, no additional mode bit is transmitted. The random-codebook size is switched with the backward adaptively selected mode. The subjective quality of unvoiced speech or noise-like signal can be improved by this switching operation because the random-codebook size is greatly increased in such signal mode. The dispersed-pulse structure provides better performance of sparse pulse excitation using dispersed pulses instead of simple unit pulses. The noise post-processing employs a stationary background noise generator for producing stationary noise signal. It significantly improves subjective quality of decoded signal under various background noise conditions. Subjective listening tests are conducted in accordance with ACR and DCR tests. The ACR test results indicate that the fundamental performance of the MDP-CELP is equivalent to that of 32-kbit/s adaptive differential pulse code modulation (ADPCM). The DCR test results show that the performance of the MDP-CELP is equivalent to or better than that of 8-kbit/s conjugate-structure algebraic code excited linear prediction (CS-ACELP) under several background noise conditions.

We demonstrated variable dispersion compensation using the Virtually Imaged Phased Array (VIPA) for a 40-Gbit/s dense-WDM transmission system. The large tunable range from -800 to +800 ps/nm in the entire C-band wavelength range and the high tunable resolution of 1 ps/nm was achieved by using a 3-dimensional mirror equipped with a stepping motor that we developed. We adopted the dispersion monitor of 40-GHz intensity extracted from the received 40-Gbit/s baseband signals, and verified that this dispersion monitoring method is applicable to nonlinear transmission by detecting the monitor peak. Using the VIPA variable dispersion compensator and the dispersion monitor, we demonstrated 1.28-Tbit/s (40-Gbit/s 32 ch) automatic dispersion compensation. As a result, we confirmed that only two VIPAs and one fixed dispersion compensating fiber (DCF) are needed to make our method applicable to the entire C-band for dense WDM 40-Gbit/s systems having a large transmission range of 80 km.

This paper proposes a statistical design approach for Non-Return-to-Zero (NRZ) 40 Gbit/s systems with Forward Error Correction (FEC); the approach considers Polarization Mode Dispersion (PMD). We introduce a fluctuating PMD emulator to experimentally clarify FEC performance in PMD-limited systems. By using the proposed design approach, and considering the FEC relaxation effect on PMD, the maximum transmission distance of an NRZ 40 Gbit/s system without PMD compensation is estimated as several hundreds of km depending on the number of cable concatenations per link and the probability threshold of system acceptance.

It has been shown that virtual output queuing (VOQ) and a sophisticated scheduling algorithm enable an input-queued switch to achieve 100% throughput for independent arrival process. Several of the scheduling algorithms that have been proposed can be classified as either iterative scheduling algorithms or symmetric crossbar arbitration algorithms. i-OCF (oldest-cell-first) and TSA (two step arbiter) are well-known examples of iterative scheduling algorithms and symmetric crossbar arbitration algorithms, respectively. However, there are drawbacks in using these algorithms. i-OCF takes long time to find completely a conflict-free match between input ports and output ports because it requires multiple iterations. If i-OCF cannot find a conflict-free match completely, the switch throughput falls. TSA has the possibility that it finds a conflict-free match faster than i-OCF because it does not need any iterations. However, TSA suffers from the starvation problem. In this paper, we propose a new scheduling algorithm. It uses two schedulers, which we call scheduler 1 and scheduler 2, in parallel. After cells were transmitted, the information that input port i granted the offer from output port j in scheduler 2 is mapped to scheduler 1 if and only if input port i has at least one cell destined for output port j. If the information is moved, input port i and output port j are matched in scheduler 1 at the beginning of the next time slot. Our proposed algorithm uses one scheduler based on TSA and the other scheduler based on i-OCF. Numerical results show that the proposed scheduling algorithm does not require multiple iterations to find a conflict-free match completely and suffer from the starvation problem for both uniform and bursty traffic.