In our previous research, to achieve unequal error protection (UEP), we proposed a scheme which encodes the data by randomly switching between several codes which use different signal constellations and showed the effectiveness in AWGN channels. In this letter, we propose our UEP system using MMSE-FDE for fast and selective fading by using the fact that importance levels are changed every few symbols, i.e., every block, in the proposed system. We confirmed the improvement in BER performance and the effectiveness of adaptive equalization for the proposed system in fading channels. Moreover, in fading channels we confirmed the validity of the theoretical tradeoff shown in static conditions.

In order to realize millimeter-wave (MMW) 3-D system-in-package (SiP) front-end modules, we propose a 60-GHz band copper ball vertical interconnection structure, which interconnects between vertically stacked substrates. The structure enables ICs to be placed between the vertically stacked substrates. Since the diameter of the copper balls must exceed the thickness of the ICs, the distance between the substrates in the modules is larger than that of the flip-chip interconnection widely used in the MMW-band. Therefore, the conventional flip-chip interconnection does not scale for the interconnection between the substrates in MMW 3-D SiP front-end modules. The layout of grounded copper balls and the patterns of inner ground layers in the upper/lower substrates are designed using 3-D electromagnetic field simulation. The designed structure allows less than 1 dB transmission loss up to 71.1 GHz, compared with a through transmission line. The result is verified with fabrication and measurement and confirms the feasibility of MMW 3-D SiP front-end modules.

The next generation video coding standard HEVC shows high coding performance compared with the H.264/AVC standard, but the computational complexity of the HEVC encoder (HM3.0) is significantly higher. In this letter, the early termination of the CU encoding algorithm is proposed to reduce the computational complexity in the HEVC encoder. The proposed method reduces the encoder complexity by 58.7%, while maintaining the same level of coding efficiency.

A sensing efficiency optimization scheme based on two-stage spectrum sensing that maximizes the achievable throughput of the secondary network and minimizes the average sensing time is proposed in this paper. A selection method for the threshold is proposed and proved to ensure optimal sensing performance. An effective iterative algorithm is presented to solve the constructed efficiency optimization problem.

Polycrystalline Cu(In,Ga)Se2 (CIGS) films were prepared by heat treatment of metallic precursors using dimethylselenium (Se(CH3)2), which is a less hazardous Se source than H2Se gas. CIGS films were fabricated at various Se(CH3)2 supply rates. We investigated the effect of the Se(CH3)2 supply rate on the crystal phase and surface morphology of the films.

In this paper, a wideband CMOS radio frequency (RF) front-end for digital video broadcasting-handheld (DVB-H) receiver is proposed. The RF front-end circuit is composed of a single-ended resistive feedback low noise amplifier (LNA), a single-to-differential amplifier, an I/Q down-conversion mixer with linearized transconductors employing third order intermodulation distortion cancellation, and a divide-by-two circuit with LO buffers. By employing a third order intermodulation (IMD3) cancellation technique and vertical NPN bipolar junction transistor (BJT) switching pair for an I/Q down-conversion mixer, the proposed RF front-end circuit has high linearity and low low-frequency noise performance. It is fabricated in a 0.18 µm deep n-well CMOS technology and draws 12 mA from a 1.8 V supply voltage. It shows a voltage gain of 31 dB, a noise figure (NF) lower than 2.6 dB, and an IIP3 of -8 dBm from 470 MHz to 862 MHz.

Mining and explaining relationships between concepts are challenging tasks in the field of knowledge search. We propose a new approach for the tasks using disjoint paths formed by links in Wikipedia. Disjoint paths are easy to understand and do not contain redundant information. To achieve this approach, we propose a naive method, as well as a generalized flow based method, and a technique for mining more disjoint paths using the generalized flow based method. We also apply the approach to classification of relationships. Our experiments reveal that the generalized flow based method can mine many disjoint paths important for understanding a relationship, and the classification is effective for explaining relationships.

A low cost, ultra small Radio Frequency (RF) transceiver module with integrated antenna is one of the key technologies for short range millimeter-wave wireless communication. This paper describes a 60 GHz-band transmitter module with integrated dipole antenna. The module consists of three pieces of low-cost organic resin substrate. These substrates are vertically stacked by employing Cu ball bonding 3-dimensional (3-D) system-in-package (SiP) technology and the MMIC's are mounted on each organic substrates by using Au-stud bump bonding (SBB) technique. The planer dipole antenna is fabricated on the top of the stacked organic substrate to avoid the influence of the grounding metal on the base substrate. At 63 GHz, maximum actual gain of 6.0 dBi is obtained for fabricated planar dipole antenna. The measured radiation patterns are agreed with the electro-magnetic (EM) simulated result, therefore the other RF portion of the 3-D front-end module, such as flip chip mounted IC's on the top surface of the module, does not affect the antenna characteristics. The results show the feasibility of millimeter-wave low cost, ultra small antenna integrated module using stacked organic substrates.

On the 11th of March, 2011, a massive earthquake hit the northeast region of Japan. The government of Japan needed to publish information regarding the earthquake and its influences. However, their capacity of Web services overflowed. They called the industry and academia for help for providing stable information service to the people. Industry and academia formed a team to answer the call and named themselves the “EQ project”. This paper describes how the EQ Project was organized and operated, and gives analyses of the statistics. An academic organization took the lead in the EQ Project. Ten organizations which consisted of commercial IT industry and academics specialized in Internet technology, were participating in the EQ Project and they structured the three clusters based on their relationships and technological approach. In WIDE Cluster, one of three clusters in the structure of EQ, the peak number of file accesses per day was over 90 thousand, the mobile browsers was 3.4% and foreign languages (translated contents) were referred 35%. We have also discussed the future information distribution strategies in emergency situation based on the experiences of the EQ Project, and proposed nine suggestions to the MEXT as a future strategy.

To improve TCP throughput even if the maximum receiving window size is small, a TCP performance enhancing proxy (PEP) using a UDP-like packet sending policy with error control has been proposed. The PEP operates on a router along a TCP connection. When the PEP receives a data packet from the source host, it transmits the packet to the destination host, copies the packet into the local buffer (PEP buffer) in case the packets need to be transmitted and sends a premature ACK acknowledging receipt of the packet to the source host. In the PEP, the number of prematurely acknowledged packets in the PEP buffer is limited to a fixed threshold (watermark) value to avoid network congestion. Although the watermark value should be adjusted to changes in the network conditions, watermark adjusting algorithms have not been investigated. In this paper, we propose a watermark adjusting algorithm the goal of which is to maximize the throughput of each connection as much as possible without excessively suppressing the throughputs of the other connections. In our proposed algorithm, a newly established connection uses the initial watermark value of zero to avoid drastic network congestion and increases the value as long as its throughput increases. In addition, when a new connection is established, every already-established connection halves its watermark value to allow the newly established connection to use some portion of the bandwidth and increases again as long as its throughput increases. We compare the proposed algorithm (CW method) with other methods: the FW method that uses a fixed large watermark value and the NP method that does not use the PEP. Numerical results with respect to throughput and fairness showed that the CW method is generally superior to the other two methods.

This paper presents the design and implementation of 0.9–4.8 GHz CMOS power amplifier (PA) with improved group delay variation and gain flatness at the same time for UWB transmitters. This PA design employs a two-stage cascade common source topology, a resistive shunt feedback technique and inductive peaking to achieve high gain flatness, and good input matching. Based on theoretical analysis, the main design factor for group delay variation is identified. The measurement results indicate that the proposed PA design has an average gain of 10.2 ± 0.8 dB while maintaining a 3-dB bandwidth of 0.57 to 5.8 GHz, an input return loss |S11| less than -4.4 dB, and an output return loss |S22| less than -9.2 dB over the frequency range of interest. The input 1 dB compression point at 2 GHz was -9 dBm while consumes 30 mW power from 1.5 V supply voltage. Moreover, excellent phase linearity (i.e., group delay variation) of ±125 ps was achieved across the whole band.

Because large earthquakes have repeatedly occurred in subduction zones, it is important to observe seismic activities on the sea floor. An ocean bottom cabled seismometers (OBCS) system is the most suitable tool for this purpose since data can be obtained in real-time. Although the existing OBCS systems are useful for the study of seismic activities, the number of stations is limited due to their cost. Therefore, lower cost in both production and installation is desired. We have developed a new OBCS system utilizing IP technologies. IP technologies yield the new OBCS system that are more compact and less expensive, while a large amount of complex hardware is used in the existing OBCS system. System reliability is ensured by using IP network technologies that provide redundancy. The new OBCS system was first installed to observe the Niigata-Kobe tectonic zone in the Japan Sea on September 2010. Although this first OBCS system has a total length of 25 km, it has been proven that seismic data can be successfully obtained and that the new OBCS system is effective and useful for the dense observation of seismogenic activities on the sea floor around Japan.

The design and measured results of a 120-GHz transmitter and receiver chipset are described in this paper. A simple on-off keying (OOK) modulation is adopted for low power consumption. The proposed transmitter and receiver are fabricated using 65-nm CMOS technology. The current consumption of the transmitter and receiver are 19.2 mA and 48.2 mA respectively. A 9-Gbps PRBS is successfully transferred from the transmitter to the receiver with the bit error rate less than 10-9.

A nanowatt-power-level automatic switch that combines a multi-Vth CMOS level converter and an LED as a photodiode has been developed for a sensor application. The level converter is a single-input latch-type multi-Vth CMOS circuit featuring the use of an enhancement-mode nMOSFET and a depletion-mode common-gate nMOSFET as a pair of driver transistors. The ED-CMOS level converter cuts the DC current path; and the LED, which generates a high output voltage under illumination, suppresses the leakage current of the depletion-mode common-gate nMOSFET in the ED-CMOS level converter, resulting in nanowatt-order power dissipation. To verify the effectiveness of the ED-CMOS circuit, a prototype level converter was fabricated on a 0.6-µm CMOS process and used in an automatic switch in a wireless mouse. The switch is composed of two LEDs, a current-mirror circuit, the level converter, and a power switch MOSFET. It senses when a hand grabs or releases the mouse and automatically turns the mouse on or off, respectively. The measured power dissipation of the mouse is 3 nW in the standby mode.

Multicast routing with Quality-of-Service (QoS) guarantees is the key to efficient content distribution and sharing. Developing QoS-aware multicast routing algorithm is an important open topic. This paper investigates QoS-aware multicast routing problem with K constraints where K > 2. The contributions made in this paper include a heuristic that employs the concept of nonlinear combination to extend the existing well-known algorithm for fast computation of a QoS multicast tree, and a Fully Polynomial Time Approximation Scheme (FPTAS) to approximate a multicast routing tree with QoS guarantees. The theoretical analyses and simulations conducted on both algorithms show that the algorithms developed in this paper are general and flexible, thus are applicable to the various networking systems.

A user identity anonymity is an important property for roaming services. In 2011, Kang et al. proposed an improved user authentication scheme that guarantees user anonymity in wireless communications. This letter shows that Kang et al.'s improved scheme still cannot provide user anonymity as they claimed.

The Direct Sampling Mixer (DSM) with a complex coefficient transfer function is demonstrated. The operation theory and the detail design methodology are discussed for the high order complex DSM, which can achieve large image rejection ratio by introducing the attenuation pole at the image frequency band. The proposed architecture was fabricated in a 65 nm CMOS process. The measured results agree well with the theoretical calculation, which proves the validity of the proposed architecture and the design methodology. By using the proposed design method, it will be possible for circuit designers to design the DSM with large image rejection ratio without repeated lengthy simulations.

In 2009, Wang et al. proposed an efficient and secure dynamic ID-based remote user authentication scheme based on the one-way secure hash function. This letter demonstrates that Wang et al.'s scheme is still vulnerable to impersonation attacks.

In this letter, we propose a computationally efficient maximum likelihood log-likelihood ratio (LLR) calculation method for multiple input multiple output (MIMO) systems with two spatial streams.

Shape is one of the primary low-level image features in content-based image retrieval. In this paper we propose a new shape description method that consists of a rotationally invariant angular radial transform descriptor (IARTD). The IARTD is a feature vector that combines the magnitude and aligned phases of the angular radial transform (ART) coefficients. A phase correction scheme is employed to produce the aligned phase so that the IARTD is invariant to rotation. The distance between two IARTDs is defined by combining differences in the magnitudes and aligned phases. In an experiment using the MPEG-7 shape dataset, the proposed method outperforms existing methods; the average BEP of the proposed method is 57.69%, while the average BEPs of the invariant Zernike moments descriptor and the traditional ART are 41.64% and 36.51%, respectively.