This paper presents an overview of research, development, standardization and regulation activities on ultra wideband (UWB) technologies in National Institute of Information and Communications Technology (NICT). NICT started a project on UWB technologies since 2002, and organized UWB consortium in cooperation with more than 20 companies and 7 universities in Japan. Up to now, we have been conducting numerous UWB R&D including the following main works: i) key technology development such as MMIC chips, antennas and other devices, ii) measurement and channel modeling for UWB signal propagation, iii) standardization in international activities of IEEE 802.15, ITU-R TG1/8 as well as in a national regulatory committee of Ministry of Internal Affair and Communications (MIC). The UWB systems we have studied occupy frequency bands range from microwave band (3-5 GHz) to quasi-millimeter wave band (24-29 GHz). Various prototype UWB systems including multi-functional terminals have been developed. The output of NICT has been succeeded by industrial parties with with national and international standardization and regulation.

This paper introduces a block based motion estimation algorithm based on projection with adaptive window size selection. The blocks cannot match well if their corresponding 1D projection does not match well, with this as foundation 2D block matching problem is translated to a simpler 1D matching, which eliminates majority of potential pixel participation. This projection method is combined with adaptive window size selection in which, appropriate search window for each block is determined on the basis of motion vectors and prediction errors obtained for the previous block, which makes this novel method several times faster than exhaustive search with negligible performance degradation. Encoding QCIF size video by the proposed method results in reduction of computational complexity of motion estimation by roughly 45% and over all encoding by 23%, while maintaining image/video quality.

The Video Quality Experts Group (VQEG) is preparing a programme of subjective multimedia quality tests. The results from these tests will be used to evaluate the performance of competing objective multimedia quality metrics. The reliability of the subjective test data is of great importance for VQEG's task. This paper provides an overview of VQEG's multimedia ad-hoc group. The work of this group will require subjective tests to be performed by laboratories located in Europe, Asia and North America. For VQEG's multimedia work to be successful, the subjective assessment methodology must be precisely defined and produce reliable and repeatable subjective quality data. Although international standards covering multimedia quality assessment methods are in force, there remains some uncertainty regarding the most effective approach to assessing the subjective quality of multimedia. A review of existing methods is provided. Two experiments are presented investigating the suitability of alternative subjective assessment methods (single-stimulus ACR and SAMVIQ). The results of these experiments are discussed within the context of the VQEG multimedia testing programme.

We have developed a solid-electrolyte nonvolatile switch (here we refer as NanoBridge) with a low ON resistance and its small size. When we use a NanoBridge to switch elements in a programmable logic device, the chip size (or die cost) can be reduced and performance (speed and power consumption) can be enhanced. Developing this application required solving a couple of problems. First, the switching voltage of the NanoBridge (0.3 V) needed to be larger than the operating voltage of the logic circuit (>1 V). Second, the programming current (>1 mA) needed to be suppressed to avoid large power consumption. We demonstrate how the Nanobridge enhances the switching voltage and reduces the programming current.

This paper proposes two efficient rate control algorithms for Motion JPEG2000. Both methods provide accurate visual quality control under buffer constraints. Frames of the same scene usually have the similar rate-distortion (R-D) characters. The proposed methods predict the R-D models of uncoded frames forwardly or bilaterally according to those of coded frames. Experimental results demonstrate that the proposed algorithms offer visual quality improvements over similar competing methods and save a large amount of memory simultaneously.

A novel UWB system for a new indoor short distance radio-communication is examined. Various types of UWB systems have been proposed in the literature. Particularly direct sequence (DS) systems and time hopping (TH) systems are attractive due to low power consumption and a simple transceiver construction. In this paper, we consider to apply modulated and modified Hermite pulses (MMHP) for both DS-UWB and TH-UWB systems. Furthermore, MMHP are extended to a novel pulse set referred as limited bandwidth MMHP set in order to reduce various interferences. It is composed of pseudo-orthogonal pulses that have both good auto-correlation characteristics in all orders and low cross-correlation characteristics between different orders. The proposed pulse set also have some specific notches, which can be used to reduce narrow-band interference (NBI). Additionally, we propose a novel pulse shape hopping that employs the proposed MMHP set. Multi-user interference (MUI) and inter-symbol interference (ISI) can be reduced by such a pulse shape hopping scheme for the DS or TH UWB signal format. Simulation results show significant performance improvements by using the proposed UWB system.

This paper considers systems consisting of communicating processes which can move between specified locations. Mobile telephone systems and intelligent transport systems are examples of them. The processes can exchange data as well as channels (e.g. frequencies) to be used in further communication. It may happen that two processes (e.g. telephones or cars) in different locations could communicate directly because they share a communication channel, but they cannot as there is a physical obstacle between the locations. A possible solution is to allow one process to send a message to another one through other processes and locations. To see if this is possible, a notion of connectivity of processes has been devised in the literature. A process was defined to be connectable to another one if a message from the first one could reach the other one by using any existing communication actions, allowed locations, and process moves in the system. A process-algebraic approach for checking connectivity was proposed. In this paper, it is shown how the temporal logic of actions (TLA) can be employed for the same purpose. In both approaches, connectivity of a process with another one is basically checked as follows. The first process includes a marking message in all its sending actions. Every process that receives this message gets marked and includes it in its own sending actions. The first process is connectable to the second one if there exists such a system execution sequence that the latter gets marked in it. Since TLA is a linear-time temporal logic, it can generally not express such a property. This paper, however, shows that it can be expressed and verified for a given TLA system specification. It also shows how to specify the marking operations and provides an example of connectivity checking.

This paper describes a new low-power write driver circuit for mobile hard disk drive preamplifiers. To achieve low power consumption, we developed a write driver circuit with a single-stage MOS transistor as the current driver, which both switches and controls the write current. We also developed a reflection cancellation method to suppress the distortion of the write current waveform during write transition. Fabricated using 0.35-µm SOI-BiCMOS technology, this write driver circuit consumes low power, 380 mW (at 100 MHz).

Emerging GMPLS (Generalized Multi-Protocol Label Switching)-based photonic networks are expected to realize the dynamic allocation of network resources for a wide range of applications, such as carriers' backbone networks as well as enterprise core networks and GRID computing. To address diverse reliability requirements corresponding to different application needs, photonic networks have to support various optical path recovery schemes. Thus GMPLS standardization bodies have developed failure recovery protocols for 1+1 protection, 1:N protection and restoration, with support of extra traffic and shared use of back-up resources. Whereas the standardization efforts cover a full spectrum of recovery schemes, there have not been many reports on actual implementations of such functionalities, and none of them included extra traffic. This paper introduces an OXC (Optical Cross Connect) implementation of GMPLS's failure recovery functionalities supporting 1+1 protection, M:N protection and extra path. Here extra path is an extension of GMPLS protection's extra traffic which can partially reuse protected paths' back-up resources. Evaluation of the implementation confirms rapid recovery of protected traffic upon a failure, even when preemption of an extra path is involved. It is also shown that its preemption scheme can resolve the issue of the poor scalability of GMPLS-based preemption when multiple extra paths are preempted upon a failure.

This paper describes optimization of H10-to- E01 mode converter by way of a right-angle E-plane junction (RAJ) between a rectangular waveguide and a circular waveguide in a waveguide rotary joint. Requirements for the optimized mode converter are formulated to provide the conjugate matching condition and analytical formulas for the rotary joint. A novel design procedure of the mode converter is proposed. An excellent performance of the mode converter fabricated for the Ka-band rotary joint is proved by computer simulation and the experimental results. The return loss and the insertion loss rotational effect are less than -25 dB and 0.02 dB in the 10% bandwidth, respectively.

We propose a hybrid voice conversion method which employs a combination of techniques using HMM-based unit selection and spectrum generation. In the proposed method, the HMM-based unit selection selects the most likely unit for the required phoneme context from the target speaker's corpus when candidates of the target unit exist in the corpus. Unit selection is performed based on the sequence of the spectral probability distribution obtained from the adapted HMMs. On the other hand, when a target unit does not exist in a corpus, a target waveform is generated from the adapted HMM sequence by maximizing the spectral likelihood. The proposed method also employs the HMM in which the spectral probability distribution is adjusted to the target prosody using the weight defined by the prosodic probability of each distribution. To show the effectiveness of the proposed method, sound quality and speaker individuality tests were conducted. The results revealed that the proposed method could produce high-quality speech and individuality of the synthesized sound was more similar to the target speaker compared to conventional methods.

An enhanced Ultra Wideband (UWB) signaling scheme that employs PSWF (Prolate Spheroidal Wave Functions)-based orthogonal chip pulses and ternary complementary code sets is proposed for Direct-Sequence (DS) UWB systems. Every information bit of each user is modulated and transmitted over a set of parallel sequences of PSWF-based orthogonal chip pulses and are further assigned to a ternary complementary code set with additional zero padding if necessary. Moreover, the ternary complementary code sets are generated to be mutually orthogonal and assigned to any pair of multiple users. Hence, the mitigation of multipath interference as well as multiple user interference (MUI) can be expected. Furthermore, the ternary code length can be greatly shortened by taking advantage of pulse and code orthogonality. Thus, the proposed transmission scheme is especially suitable for high data rate DS-UWB systems that offer very high flexibility.

In this paper, a novel cost effective interconnection network for two-way pipelined SIMD-based reconfigurable computing processor is proposed. Our reconfigurable computing engine is composed of the SIMD-based function units, flexible interconnection networks, and two-bank on-chip memories. In order to connect the function units, the reconfigurable network is proposed to connect all neighbors of each function unit. The proposed interconnection network is a kind of full and bidirectional connection with the data duplication to perform the data-parallelism applications efficiently. Moreover, it is a multistage network to accomplish the high flexibility and low hardware cost.

This paper presents a semi-blind algorithm for multiuser interference cancellation and fading amplitude estimation for downlink MIMO DS-CDMA systems with multipath fading channels. Taking advantage of the space-time information of the parametric multipath channel, the proposed algorithm first uses a space-time channel decoupler to suppress multiuser interference and then decomposes the channel into a set of parallel subchannels each containing the signal of the desired user on an individual multipath. Two criteria, the complementary orthogonal projection (COP) and the minimum variance distortionless response (MVDR), are employed by the space-time decoupler to achieve interference suppression and signal separation. The fading amplitudes can then be estimated from the eigen space of the output of the space-time channel decoupler. It follows that the signal of interest can be maximally combined in a pathwise manner and then differentially decoded.

An analytic approach for the generation of non-periodic and periodic complementary sequences is advanced for lengths that are powers of two. The periodic complementary sequences can be obtained using symmetric or anti-symmetric extensions. The properties of their autocorrelation functions are studied. The non-periodic complementary sequences are the intersection between anti-symmetric and symmetric periodic sequences. These non-periodic and periodic complementary sequences are identified to be special cases of non-periodic and periodic (or cyclic) orthogonal wavelet transforms. This relationship leads to the novel approach.

This paper provides an overview of the new tendencies in the subjective assessment of the quality of video for Multimedia applications. New subjective assessment methods are here described together with the description of the new general approaches. Some motivations of these new approaches are also here provided.

Active Queue Management (AQM) based on nonlinear difference equations is proposed to solve the end-to-end TCP network congestion problem. The proposed AQM scheme can guarantee the stability of the multiple bottleneck network by nonlinear control of dropping probability of the routers by imposing some restrictions on the AQM parameter. Nonlinear control often relies on some heuristics and network traffic controllers that appear to be highly correlated with the multiple bottleneck network status. Based on the proposed nonlinear difference equations for TCP flows control across the network, this paper reveals the reasons of congestion of multiple bottleneck AQM, and provides a theorem for avoiding network congestion. Moreover, we give simulations to verify the results for nonlinear control of the multiple bottleneck network congestion.

In this paper, we evaluate the performance of asymmetric Time Division Duplex (TDD) system that employs Adaptive Modulation and Coding (AMC) and Hybrid ARQ, with consideration of the effect of control delays in TDD. Channel reciprocity characteristic in TDD allows utilization of open loop channel estimation to choose appropriate modulation and coding scheme (MCS) level for AMC. However, control delay in AMC and HARQ depends on TDD time slot allocation formats. Large control delay in AMC will result in false MCS selection due to the poor channel correlation between measured channel state from the received signals and instantaneous channel state of actual transmission with the MCS selected based on the measured channel state. We present an analytical approach to calculate the probability of MCS level selection error in different channel conditions for different asymmetric time slot allocations. From the theoretical and simulation results, it is shown that the instantaneous throughput per slot depends not only on maximum Doppler frequency but also on asymmetric slot allocations. Average delay time that yields error free packet reception in the downlink increases as the number of continuous downlink slots increases.

Diversity transmission using space-time block coding (STBC) shows a degraded performance in frequency selective fading (FSF) channel. In this paper, assuming the CSI is unknown at both transmitter and receiver while a pilot signal is available during the training period, we propose a MIMO transmission scheme using STBC by adopting subband adaptive array (SBAA) processing. The receive signal is converted into the frequency-domain and adaptive processing is done at each subband. A novel construction of SBAA is introduced to process received signal based on STBC. Simulation results demonstrate that the proposed scheme has a better performance compare to conventional STBC, and has a better performance and less computational load compare to STBC-TDLAA.

Pneumatic pressure, which is easy enough to be handled in comparison with hydraulic pressure and is endowed with high safety, is available for a power source of a robot arm to be utilized in concert with human beings to do various types of work. But pneumatic pressure is so low in comparison with hydraulic pressure that an air cylinder having a diameter long enough and stroke wide enough is required to obtain great output power. In this study, therefore, the investigation was made with layout of air cylinders and transmission mechanisms of the motion power directed toward the driving joints to be followed by development of a new humanoid robot arm with seven degrees of freedom in which air cylinders are compactly incorporated. To be concrete with this, contrivance was made with an endoskeleton structure allowing almost all of the structure materials of the individual arm joints to be shared by the air cylinder with incorporation of the air cylinder in the axes of the upper arm joint and forearm joints by paying attention to the fact that the cylinder itself has high strength. The evaluation experiments driving the robot arm referred to above were conducted by means of I-PD control. The results suggested that the mechanism of the robot with seven degrees of freedom having pneumatic actuators proposed in this study is useful as the humanoid robot arm. The quick and accurate motions were accomplished with I-PD control which is relatively easy to be dealt with but not suitable for non-linear actuator system.