Filtering and smoothing using a non-Gaussian state space model are proposed for motion trajectory of feature point in image sequence. A heavy-tailed non-Gaussian distribution is used for measurement noise to reduce the effect of outliers in motion trajectory. Experimental results are presented to show the usefulness of the proposed method.

In this paper, we investigate the bit error rate (BER) of OMC-CDMA (Orthogonal Multi-Carrier-Code Division Multiple Access) with Maximal Ratio Combining (MRC) scheme on two-ray Rayleigh multipath fading channels, and compare the MRC scheme with the Equal Gain Combing (EGC) scheme according to not only the number of users (M) and subcarriers (N) but also the power of delayed signal. We found that the MRC scheme outperforms the EGC scheme, and the BER of OMC-CDMA depends greatly on the power of delayed signal. If the delayed path power is increased from 10% to 50%, as compared with the direct path power, CDMA capacity is decreased approximately by 30% at BER=10-3, N=256 and SNR=15 dB. When the system is heavily loaded by users in large decaying parameter, the performance of OMC-CDMA with the MRC scheme can not increase the BER significantly compared to that with the EGC scheme.

This letter presents a method which attempts to minimize the number of spill codes to resolve usage conflicts of distributed registers in application specific DSPs. It searches for a set of ordering restrictions among operations which sequentialize the lifetimes of the values residing in the same register as much as possible. Experimental results show that the proposed analysis method reduces the number of register spills into 28%.

We will present the theoretical analysis of and experimental measurements on the transmission characteristics of multi-channel long period fiber gratings in terms of the physical parameters like the separation distance, grating length and number of gratings. These parameters can be used to control the spectral channel spacing, number of channels, loss peak depth, and channel bandwidth of multi-channel long period fiber gratings.

The analytic expression for the transmission spectrum of cascaded long-period fiber gratings is presented in a closed form. When several identical gratings are cascaded in-series with a regular distance, the transmission spectrum is revealed to have a series of regularly spaced peaks, suitable for multi-channel filters. The analytic solution is obtained by diagonalizing the transfer matrix of each grating unit that is composed of a single grating and a grating-free region between adjacent gratings. The spectrum of the device is simply described with the number of cascaded gratings and a single parameter that has the information of the phase difference between the modes. With the derived equation, the spectral behaviors of the proposed device are investigated. The intensity of each peak can be controlled by adjusting the strength of a single grating. The separation between adjacent gratings determines the spacing between the peaks. The finesse of the peaks can be increased by cascading more gratings. The derived analytic results are compared with the known results of paired gratings and phase-shifted gratings.

The uniform switching system is the family of non-linear n m binary arrays constrained such that all columns are from the constant weight k vectors and all rows have weights divisible by p > 0. For this system, we present a cardinality formula and an enumerative algorithm.

An experimental report was presented on a high temperature performance of a ZrN barrier in the model system of W/ZrN/poly-Si as a poly-metal gate electrode configuration. The absence of interdiffusion, reaction and/or mixing of the ZrN barrier with adjoining W and poly-Si layers resulted in a successful demonstration of the thermally stable poly-metal gate electrode configuration which tolerated annealing at 850 for 1 h.

Arts and Giesl introduced the notion of dependency pairs, which gives effective methods for proving termination of term rewriting systems (TRSs). In this paper, we extend the notion to AC-TRSs, and introduce new methods for effectively proving AC-termination. It is impossible to directly apply the notion of dependency pairs to AC-TRSs. To avoid this difficulty, we introduce the notion of extended dependency pairs. Finally we define the AC-dependency pair and the AC-dependency chain. Furthermore, we propose approximated AC-dependency graphs, which is very useful for proving AC-termination in practice, using the approximation technique based on Ω-reduction and ΩV-reduction.

We propose the problem of how to transmit an information-theoretically secure bit using random deals of cards among players in hierarchical groups and a computationally unlimited eavesdropper. A player in the highest group wants to send players in lower groups a secret bit which is secure from the eavesdropper and some other players. We formalize this problem and design protocols for constructing secret key exchange spanning trees on hierarchical groups. For each protocol we give sufficient conditions to successfully construct a secret key exchange spanning tree for the hand sizes of the players and the eavesdropper.

In an ideal fiber grating having a uniform refractive index modulation, the reflection or the transmission spectrum is symmetric with equal amount of side lobes on both sides of the resonant wavelength of the fiber grating. It is observed that a long-period fiber grating made by a non-uniform UV laser beam through a uniform amplitude mask has an asymmetric transmission spectrum. The asymmetric characteristic is explained with Mach-Zehnder effect in the long-period fiber grating. The non-uniform UV laser beam makes also a non-uniform index modulation along the fiber core. Therefore, a beam coupled to a cladding mode at a section of the grating can be re-coupled to the core mode after passing a certain distance. The re-coupled beam makes Mach-Zehnder-like interference with the un-coupled core mode. However, it is presented that the asymmetric phenomenon can be overcome by scanning the UV laser beam along the fiber over the mask. The beam scanning method is able to suffer the same fluence of the UV laser beam on the fiber. Finally, a linearly chirped long-period fiber grating was made using the non-uniform UV laser beam. Due to the asymmetricity the chirping effect was not clearly observed. It is also presented that the beam scanning method could remove the asymmetric problem and recover the typical spectrum of the linearly chirped fiber grating.

This paper proposes Photonic Core Node based on a 2.56-Terabit/s opto-electronic switching fabric, which can economically handle the rapidly increasing multimedia traffics, such as Internet traffic. We have successfully developed the first prototype of Photonic Core Node. The prototype consists of a single-stage full-crossbar opto-electronic switching fabric, super-packet buffers for input queuing, and a desynchronized-round-robin scheduler. The switching fabric is upgradable up to 2.56 Tb/s, and employs wavelength-division-multiplexing techniques, which dramatically reduce the total number of optical switching elements down to one-eighth the number of those used in a conventional switching fabric. The super-packet buffer assembles 16 ATM cells routed to the same output port into a single fixed-length packet. The super-packet-switching scheme drastically reduces the overhead of optical switching from 32 to 2.9%, although it tends to decrease effective throughput. The desynchronized-round-robin scheduler maintains nearly 100% effective throughput for random traffic, recursively resolving the contention of connection requests in one scheduling routine while keeping fairness in a round robin manner. The proposed Photonic Core Node can accommodate not only ATM switching but also WDM optical path grooming/multiplexing, and IP routing by using IP input buffer interfaces, because optical switches are bit-rate/format-independent.

Voice over IP (VoIP) is a generic name for services, systems and technology for telephony over an IP network. It is also referred to as Internet telephony and IP (Internet Protocol) telephony. Internet telephone client software attracted attention when it first appeared in 1995. Since that, VoIP has rapidly matured into a practical technology, propelled by the popularization and rapid development of the Internet. IP network traffic already exceeds telephone network traffic and is expected to further increase several-fold in the next few years. In future, the telephone network will be integrated into the IP network and telephony will become entirely VoIP. There are three expectations for VoIP. The first is inexpensive telephone service. The second expectation is for integrated telephony and IP network services such as a CTI (Computer Telephony Integration) system in which there is interworking with various Internet applications, such as e-mail and Web call-back for communication services of greater convenience rather than simple replacement of the telephone. The third expectation is for a platform for providing high-quality voice communication, multicast communication, and other such enhanced voice services that have a high degree of freedom. However, many problems remain to be overcome before the VoIP System is realized. The main problems are real-time transmission of voice that allows a smooth conversation, session control for providing a variety of services, and the proposal of new services. In this paper, we give an overview of VoIP and the problems that must be solved in order to realize it and propose some solutions regarding stream control and applications. We also describe session control and other topics that are being discussed in standardization forums.

We proposed and demonstrated a novel wavelength stabilization technique for dense wavelength division multiplexing (DWDM) systems using dithering-induced AM cancellation which improves both wavelength stability and data transmission performance. Our wavelength stabilization technique consists of an optical frequency discriminating function and a function for canceling AM components induced by frequency dithering of the light source. The frequency discrimination in this technique is based on an FM-AM conversion effect, obtained by interaction from frequency dithering of the light with the bandpass characteristic of an arrayed-waveguide grating (AWG) multiplexer. The AM cancellation function was added to suppress optical frequency discriminating errors occurring due to AM components induced by frequency dithering in this wavelength stabilization architecture. In this scheme, an electro-absorption (EA) modulator is employed not only for modulating high-speed data traffic but also for suppressing AM components induced by frequency dithering on the light signal. Since the EA modulator is usually used for modulating high-speed data traffic, dedicated optical devices are not required for suppressing the AM components. The wavelength stability of a light source can therefore be enhanced with simple architecture. In the demonstration, a reduction of fluctuations within 50 MHz versus changes in the modulation index, and long-term stability within 320 MHz after more than 60 hours was achieved in 10 Gbit/s NRZ transmission. We also confirmed that the proposed AM cancellation technique effectively reduces the transmission penalties due to frequency dithering in 10 Gbit/s NRZ data transmission performance.

We demonstrate, through numerical simulations, the possibility of trans-oceanic single channel transmission at 160 Gbit/s with no active control. This was achieved using short period dispersion management, which supports short pulse propagation at practical map strengths. We demonstrate that through careful selection and optimisation of the system parameters the performance of this system can be extended. We also define the tolerable limits of the system to the residual dispersion slope and polarisation mode dispersion.

We investigated the characteristics of optical duobinary signals in achieving high fiber input power transmission focusing on the idea of optimum residual dispersion equalization. We confirm through calculations and experiments that setting the total link dispersion at a non-zero value allows high fiber launched power (+18 dBm) and large dispersion tolerance (350 ps/nm) at 10 Gbit/s. We demonstrate repeaterless 250-km single mode fiber (SMF) transmission with a 10-Gbit/s optical duobinary signal. We also demonstrate high-speed complete optical duobinary coding and transmit synchronous digital hierarchy (SDH) frames over optical duobinary signals for the first time.

We investigate a state dependent multicast routing scheme, called Least Load Multicast Routing (LLMR), for single rate loss networks. The algorithm is based on Least Load Routing (LLR) concept and the approach is to select the least loaded links for establishing connections. An analytical model for LLMR is developed. The accuracy of the analytical model is compared with the simulation results and is found to be very good. We also develop a simplified analytical model for fully symmetrical networks, which is also verified by comparing with simulation results.

This paper focuses on a multi-beam combining scheme for DS-CDMA systems, which has RAKE combiners in multiple overlapped beams, in order to increase the reverse link capacity of DS-CDMA. This scheme is a very attractive technique because the maximal ratio combining (MRC) is carried out in space and time domains. However, in a practical situation, since the terminals in own sector are not uniformly located, the interference levels in respective beams are different. Therefore, receivers at the base station do not achieve ideal combining. This paper proposes a multi-beam combining scheme for DS-CDMA systems using weighting factor based on interference level of each beam. A fast closed loop transmission power control (TPC) scheme for the multi-beam combining system is also proposed. It is confirmed by computer simulation that the proposed scheme has excellent performance in the reverse link even if terminals in own sector are not uniformly located.

In this paper, we investigate the performance characteristics of parallel switching architectures constructed by a stack of multistage switching networks. We first find that the performances of the previously proposed parallel switching architectures are much worse than the expected ones from analytic models which are based on the assumption that traffic is uniformly distributed at each stage of a switching network. We show that this phenomenon is closely related to a traffic-distribution capability of a parallel switching system and has a large influence on the performance. From these results, we then propose an architectural solution based on the Generalized Shuffle Network (GSN) and analyze its performance by proposing a new iterative analysis method. The proposed architecture uses self-routing and deflection routing, and inherently has a traffic-distribution capability to improve switch performances such as cell loss and delay in a cost-effective manner. From the comparison of simulation and analysis results, it is shown that the developed models are quite accurate in predicting the performance of a new parallel switching system.

This paper describes a simple polarization-independent wavelength conversion method using degenerated four-wave mixing (FWM) in single-mode fibers pumped with cross-polarized high frequency, saw-tooth pulses from a single pump source. Successful polarization-independent wavelength conversion is experimentally confirmed with less than 12% and 5.6% variation using a gain-switched LD pumping and a mode-locked fiber laser pumping, respectively. We clarify that the interference effect between two orthogonal pump pulses must be taken into account to achieve a good polarization-insensitive operation, since even the small pulse edges bring about the large polarization fluctuations when they are interfered. Furthermore, it is reveal that the shorter pump pulse broadens its own spectrum due to the self-phase modulation in fibers, resulting in poor FWM efficiency. Finally, possibility of high-speed operation is discussed taking into account the pump pulse conditions.

Photonic crystals have seen major advances in the past few years in the optical range. The association of in-plane waveguiding and two-dimensional photonic crystals (PCs) in thin-slab or waveguide structures leads to good 3D confinement with easy fabrication. Such structures, much easier to fabricate than 3D PCs open many exciting opportunities in optoelectronic devices and integrated optics. We present experiments on a variety of structures and devices, as well as modelling tools, which show that 2D PCs etched through waveguides supported by substrates are a viable route to high-performance PC-based photonic integrated circuits (PICs). In particular, they exhibit low out-of-plane diffraction losses. Low-loss waveguides, high finesse microcavities, and their mutual coupling are demonstrated. PACS: 42.70 QS, 42.55 Sa, 42.82 m, 42.50-p.