We propose a novel channel model of satellite-to-ground optical transmission to achieve a global-scale high-capacity communication network. In addition, we compose an effective channel coding scheme based on low-density generator matrix (LDGM) code suitable for that channel. Because the first successful optical satellite communication demonstrations are quite recent, no practical channel model has been introduced. We analyze the results of optical transmission experiments between ground station and the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) performed by NICT and JAXA in 2008 and propose a new Markov-based practical channel model. Furthermore, using this model we design an effective long erasure code (LEC) based on LDGM to achieve high-quality wireless optical transmissions.

Pairings on elliptic curves over finite fields are crucial for constructing various cryptographic schemes. The ηT pairing on supersingular curves over GF(3n) is particularly popular since it is efficiently implementable. Taking into account the Menezes-Okamoto-Vanstone attack, the discrete logarithm problem (DLP) in GF(36n) becomes a concern for the security of cryptosystems using ηT pairings in this case. In 2006, Joux and Lercier proposed a new variant of the function field sieve in the medium prime case, named JL06-FFS. We have, however, not yet found any practical implementations on JL06-FFS over GF(36n). Therefore, we first fulfill such an implementation and we successfully set a new record for solving the DLP in GF(36n), the DLP in GF(36·71) of 676-bit size. In addition, we also compare JL06-FFS and an earlier version, named JL02-FFS, with practical experiments. Our results confirm that the former is several times faster than the latter under certain conditions.

The electric field mill in our underground observation room detected a co-seismic electromagnetic signal in the vertical electrostatic field ca. 8 s after the origin time of the Niigataken Chuetsu-oki Earthquake in 2007, but ca. 30 s before the arrival time of the P-waves.

A total-field/scattered-field (TF/SF) boundary for the constrained interpolation profile (CIP) method is proposed for multi-dimensional electromagnetic problems. Incident fields are added to or subtracted from update equations in order to satisfy advection equations into which Maxwell's equations are reduced by means of the directional splitting. Modified incident fields are introduced to take into account electromagnetic fields after advection. The developed TF/SF boundary is examined numerically, and the results show that it operates with good performance. Finally, we apply the proposed TF/SF boundary to a scattering problem, and it can be solved successfully.

The miniaturization of electronic devices is leading to the creation of body-centric wireless communications, in which wireless devices are attached to human body. However, the human body environment is often uninviting for wireless signals owing to the mutual influence between the human body and wireless devices' antennas, namely wearable antennas. Therefore, wearable antennas need to be carefully designed. In this paper, a small wearable antenna with folded ground at 2.4 GHz is proposed. The folded ground has two effects: one is to improve efficiency and the other is to enhance bandwidth. When the antenna is very close to human body, it has an efficiency of 50.7% and a wide operation bandwidth of 130 MHz.

This paper presents a new generalized single threshold model that can be used in communications and cellular networks. In the proposed model, called Single Hysteresis Model (SHM), it is assumed that the amount of resources accessible for a new call of a given class can depend on two load areas of the system. The switching between areas is modulated by the two-state Markov chain which determines the average time the system spends in a particular load area, i.e. the area in which calls of selected classes with a reduced amount of resources (high load area) and with the initial amount of resources (low load area) are serviced. The results obtained for the discussed analytical model are compared with the results of the simulation of an exemplary WCDMA radio interface carrying a mixture of different multi-rate traffic streams. The research study confirms high accuracy of the proposed model.

Irregular low-density parity-check (LDPC) codes generally have good decoding performance in the waterfall region, but they exhibit higher error floors than regular ones. In this letter, we present a hybrid method, which combines code construction and the iterative decoding algorithm, to tackle this problem. Simulation results show that the proposed scheme decreases the error floor significantly for irregular LDPC codes over binary-input additive white Gaussian noise (BIAWGN) channel.

To estimate the field emission current associated with an array of carbon nanowalls (CNWs), the model of the floating rods between anode and cathode plates was proposed. An approximate formula for the enhancement factor was derived, showing that the interwall distance of the CNW array critically affects the field emission. The field enhancement factor was almost one order of magnitude less than that of vertically aligned CNTs. Considering the field emission current density, the field emission can be optimized when the interwall distance is comparable with the wall height. For same separation distance, the macroscopic field strength of the CNW array is almost one order of magnitude higher than that of vertical CNT array to obtain the emission current of 1 mA from the cathode surface of 1 cm2.

In this paper, we introduce an LDPC decoder design for decoding a length-672 multi-rate code adopted in IEEE 802.15.3c standard. The proposed decoder features high performances in both data rate and power efficiency. A macro-layer level fully parallel layered decoding architecture is proposed to support the throughput requirement in the standard. For the proposed decoder, it takes only 4 clock cycles to process one decoding iteration. While parallelism increases, the chip routing congestion problem becomes more severe because a more complicated interconnection network is needed for message passing during the decoding process. This problem is nicely solved by our proposed efficient message permutation scheme utilizing exploited parity check matrix features. The proposed message permutation network features high compatibility and zero-logic-gate VLSI implementation, which contribute to the remarkable improvements in both area utilization ratio and total gate count. Meanwhile, frame-level pipeline decoding is applied in the design to shorten the critical path. To verify the above techniques, the proposed decoder is implemented on a chip fabricated using Fujitsu 65 nm 1P12L LVT CMOS process. The chip occupies a core area of 1.30 mm2 with area utilization ratio 86.3%. According to the measurement results, working at 1.2 V, 400 MHz and 10 iterations the proposed decoder delivers a 6.72 Gb/s data throughput and dissipates a power of 537.6 mW, resulting in an energy efficiency 8.0 pJ/bit/iteration. Moreover, a decoder of the same architecture but with no pipeline stage for low-profile application is also implemented and evaluated at post-layout level.

The IEEE802.11ac task group has announced the use of a wider channel that extends the channel bandwidth to more than 80 MHz. We present an experimental platform consisting of a baseband and a RF unit in a 22 MIMO-OFDM system for the wider channel and report its system performance results from a field experiment. The MIMO-OFDM transceiver in the baseband unit has been designed to detect real-time MIMO and provides a maximum data rate of 600 Mbps. OFDM tends to cause high peak PAPR for wider channels and distorts the power amplifier performance in the RF unit. We have improved the non-linear distortion by optimizing the OFDM preamble and evaluated its performance by conducting a simulation integrated with baseband processing and a RF. In the field experiment, our platform tested the communication performance in a farm and a passage environment.

This paper proposes a novel approach to traffic state estimation using mobile phones. In this work, a real-time traffic data collection policy based on the so-called “3R” philosophy, a unique vehicle classification method, and a reasonable traffic state quantification model are proposed. The “3R” philosophy, in which the Right data are collected by the Right mobile devices at the Right time, helps to improve not only the effectiveness but also the scalability of the traffic state estimation model. The vehicle classification method using the simple data collected by mobile phones makes the traffic state estimation more accurate. The traffic state quantification model integrates both the mean speed capacity and the density of a traffic flow to improve the comprehensibility of the traffic condition. The experimental results reveal the effectiveness as well as the robustness of the proposed solutions.

The aim of this study is to improve the accuracy of flicker parameters estimation in old film sequences in which moving objects are present. Conventional methods tend to fail in flicker parameters estimation due to the effects of moving objects. Our proposed method firstly utilizes an adaptive Gaussian mixture model (GMM)-based method to detect the moving objects in the film sequences, and combines the detected results with the histogram-matched frames to generate reference frames for flicker parameters estimation. Then, on the basis of a linear flicker model, the proposed method uses an M-estimator with the reference frames to estimate the flicker parameters. Experimental results show that the proposed method can effectively improve the accuracy of flicker parameters estimation when the moving objects are present in the film sequences.

To realize a single or several molecule device, the following are necessary: (1) an electrical wiring method that is not destructive to the molecular aggregates and does not affect the electronic state of the molecules, (2) noncontact and controllable molecular manipulation technology, (3) oriented growth techniques especially to prepare a nanodevice employing an anisotropic molecular system. In this paper, recently developed electric-field assisted growth and its application to molecular device fabrication are presented.

A carbonaceous thin film was deposited on a tungsten single emitter by electrolysis of liquid methanol. The carbonaceous single emitter was thermally treated under vacuum conditions, and changes in its field emission characteristics were examined. The field emission characteristics obeyed the Fowler–Nordheim relationship for all annealing temperatures. The turn-on voltage decreased from 1640 V to 790 V with annealing up to 1373 K.

We consider spatially-coupled protograph-based LDPC codes for the three terminal erasure relay channel. It is observed that BP threshold value, the maximal erasure probability of the channel for which decoding error probability converges to zero, of spatially-coupled codes, in particular spatially-coupled MacKay-Neal code, is close to the theoretical limit for the relay channel. Empirical results suggest that spatially-coupled protograph-based LDPC codes have great potential to achieve theoretical limit of a general relay channel.

Recently, Haley and Grant introduced the concept of reversible codes – a class of binary linear codes that can reuse the decoder architecture as the encoder and encodable by the iterative message-passing algorithm based on the Jacobi method over F2. They also developed a procedure to construct parity check matrices of a class of reversible codes named type-I reversible codes by utilizing properties specific to circulant matrices. In this paper, we refine a mathematical framework for reversible codes based on circulant matrices through a ring theoretic approach. This approach enables us to clarify the necessary and sufficient condition on which type-I reversible codes exist. Moreover, a systematic procedure to construct all circulant matrices that constitute parity check matrices of type-I reversible codes is also presented.

In this paper, we present a construction method of non-binary low-density parity-check (LDPC) convolutional codes. Our construction method is an extension of Felstrom and Zigangirov construction [1] for non-binary LDPC convolutional codes. The rate-compatibility of the non-binary convolutional code is also discussed. The proposed rate-compatible code is designed from one single mother (2,4)-regular non-binary LDPC convolutional code of rate 1/2. Higher-rate codes are produced by puncturing the mother code and lower-rate codes are produced by multiplicatively repeating the mother code. Simulation results show that non-binary LDPC convolutional codes of rate 1/2 outperform state-of-the-art binary LDPC convolutional codes with comparable constraint bit length. Also the derived low-rate and high-rate non-binary LDPC convolutional codes exhibit good decoding performance without loss of large gap to the Shannon limits.

Kudekar et al. recently proved that for transmission over the binary erasure channel (BEC), spatial coupling of LDPC codes increases the BP threshold of the coupled ensemble to the MAP threshold of the underlying LDPC codes. One major drawback of the capacity-achieving spatially-coupled LDPC codes is that one needs to increase the column and row weight of parity-check matrices of the underlying LDPC codes. It is proved, that Hsu-Anastasopoulos (HA) codes and MacKay-Neal (MN) codes achieve the capacity of memoryless binary-input symmetric-output channels under MAP decoding with bounded column and row weight of the parity-check matrices. The HA codes and the MN codes are dual codes each other. The aim of this paper is to present an empirical evidence that spatially-coupled MN (resp. HA) codes with bounded column and row weight achieve the capacity of the BEC. To this end, we introduce a spatial coupling scheme of MN (resp. HA) codes. By density evolution analysis, we will show that the resulting spatially-coupled MN (resp. HA) codes have the BP threshold close to the Shannon limit.

Thin-film transistors based on Liquid-crystalline phenylterthiophenes, 3-TTPPh-5 and 3-TTPPhF4-6 are fabricated with a spin-coating method. The devices exhibit p-type operation with the mobility on the order of 10-2 cm2V-1s-1. The field-effect mobilities of the transistors using 3-TTPPh-5 and 3-TTPPhF4-6 are almost independent of the temperature above room temperature. In particular, the temperature range in which the mobility is constant is between 230 and 350 K for 3-TTPPh-5.

A novel algorithm is presented for estimating the 3-D location (azimuth angle, elevation angle, and range) of multiple sources with a uniform circular array (UCA). Based on its centrosymmetric property, a UCA is divided into two subarrays. The steering vectors for these subarrays then yield a 2-D direction of arrival (DOA)-related rotational invariance property in the signal subspace, which enables 2-D DOA estimations using a generalized-ESPRIT algorithm. Based on the estimated 2-D DOAs, a range estimation can then be obtained for each source by defining the 1-D MUSIC spectrum. Despite its low computational complexity, the proposed algorithm can almost match the performance of the benchmark estimator 3-D MUSIC.