This paper presents a formulation of two-dimensional photonic crystal waveguide devices formed by circular cylinders. The device structures are considered as cascade connections of straight waveguides. Decomposing the structure into layers of the cylinder arrays, the input/output properties of the devices are obtained using an analysis method of multilayer structure. We introduce periodic boundary conditions in the direction perpendicular to the wave propagation, and the Floquet-modes of each layer are calculated by the Fourier series expansion method with the help of the recursive transition-matrix algorithm. Then, the input/output properties of the devices are obtained by recursive calculation of scattering matrix with each layer. The presented formulation is validated by numerical experiments by comparing with the previous works.

This letter studies application of the growing PSO to the design of DC-AC inverters. In this application, each particle corresponds to a set of circuit parameters and moves to solve a multi-objective problem of the total harmonic distortion and desired average power. The problem is described by the hybrid fitness consisting of analog objective function, criterion and digital logic. The PSO has growing structure and dynamic acceleration parameters. Performing basic numerical experiments, we have confirmed the algorithm efficiency.

This paper proposes a new kind of communication system for air traffic control over the oceans; it is particularly effective at handling high air traffic loads due to many oceanic flights. In this system, each aircraft position report is sent to its relevant ground station by forwardly relaying them via a multi hop ad-hoc network that is formed by the aircraft between this aircraft and the ground station. In addition, an effective multiple access scheme with optimal values is also proposed. This scheme enables the various aircraft involved in relaying the signal to operate autonomously in a flight-route airspace. Furthermore, two useful schemes are proposed for efficient timeslot reuse and timeslot assignment in cases of low aircraft densities: the position aided timeslot reuse (PATR) and distance based timeslot assignment (DBTA), respectively. Finally, another scheme is proposed to improve the achievable relayed packet rate under low aircraft densities, which is called interference-based node selection (IB-NS). In all, the proposed system combined with those three schemes show the availability to utilize this system for air traffic control communications, specifically on high traffic ocean routes.

In the IEEE 802.11p WAVE system, applications can directly control the transmission power of the messages sent in WAVE Short Message Protocol (WSMP). This feature enables the vehicles to control the transmission range based on the application requirements and/or the vehicle density. Seemingly straightforward, however, the distributed power control between vehicles can easily go awry. Unless carefully coordinated, the power assignments can irrevocably deviate from the vehicle density pattern. In this letter, we first show that such anomaly happens for a straightforward power control where the power level reacts to the number of messages heard from ambient vehicles. Then in order to resolve the anomaly, we propose an application layer scheme that adapts the WSMP transmission power so that the power assignments precisely reflect the vehicle density pattern.

ICA (Independent Component Analysis) has a remarkable capability of separating mixtures of stochastic random signals. However, we often face problems of separating mixtures of deterministic signals, especially sinusoidal signals, in some applications such as radar systems and communication systems. One may ask if ICA is effective for deterministic signals. In this paper, we analyze the basic performance of ICA in separating mixtures of complex sinusoidal signals, which utilizes the fourth order cumulant as a criterion of independency of signals. We theoretically show that ICA can separate mixtures of deterministic sinusoidal signals. Then, we conduct computer simulations and radio experiments with a linear array antenna to confirm the theoretical result. We will show that ICA is successful in separating mixtures of sinusoidal signals with frequency difference less than FFT resolution and with DOA (Direction of Arrival) difference less than Rayleigh criterion.

MIMO-OFDM performs signal detection on a subcarrier basis which requires high speed computation in MIMO detection due to its large computational cost. Conventional designs in a MIMO detector increase processing time in proportion to the number of subcarriers and have difficulty in real-time processing for large numbers of subcarriers. A complete pipeline MMSE MIMO detector presented in our previous work can provide high speed computation. However, it tends to be excessive in a circuit scale for small numbers of subcarriers. We propose a new scalable architecture to reduce circuit scale by adjusting the number of iterative operations according to various types of OFDM system. The proposed detector has reduced circuit area to about 1/2 to 1/7 in the previous design with providing acceptable latency time.

We have applied the open-plus-closed-loop control method, recently devised by Grosu et al., to chaos-based communications. In our method, a message is handled as if it were part of a parameter mismatch between the chaotic oscillators installed on a drive and a response system. In the drive system, the message is encrypted by adding it to a state variable of the oscillator as dynamical noise. In the response system, the message is decrypted by subtracting the chaotic signal reproduced by chaotic synchronization using the open-plus-closed-loop control method from the received signal, followed by differentiation with respect to time. When the oscillators have multiple parameter mismatches, multiple messages can be simultaneously encrypted and decrypted to achieve multiplex secure communications.

This paper investigates the communication range and interference range of millimeter-wave wireless personal area networks (WPAN) based on realistic system design. Firstly, the effective communication range of the millimeter-wave networks are calculated based on realistic physical (PHY) layer design and 60 GHz channel obtained from actual measurements. Secondly, an interference model is developed to facilitate the analysis of the impact of interferer-to-victim range on the victim link performance. It is found that system with BPSK modulation is able to support use cases with higher number of portable devices within a 3 m range, while system with 16QAM modulation is more suitable for fixed high speed data streaming devices within a shorter range of 1 m. Also, the interferer-to-victim range that causes no interference in all conditions is found to be approximately 40 m, while a 25 m range causes a typical bit error rate (BER) degradation of 1-digit (e.g. BER = 10-6 to 10-5).

In this letter, we propose a simple distributed space-frequency code with both timing errors and multiple carrier frequency offsets (CFO) in asynchronous cooperative communications. By employing both the Alamouti coding approach and the transmit repetition diversity technique, full diversity gain can be achieved by the fast symbol-wise maximum likelihood (ML) decoding at the destination node. Analysis and simulations demonstrate the effectiveness of the proposed method.

This paper investigates primary signal detection by using a quiet period (QP) in cognitive wireless communications. In particular, we provide an analytical model for studying the impact of QPs on the system performance. Our analysis shows that two successive QPs have a significant impact on system performance. Moreover, the analytical results obtained reveal an optimum period of two successive QPs that maximize system performance.

Many people have suffered and died due to a lot of large-scale disasters such as earthquake, fire, and terrorism, etc. In disasters where most evacuators become panic, two things are necessary for their immediate evacuation. The first is to estimate the location of the disaster occurrence. The second is to construct an evacuation support system that searches for safe and efficient evacuation routes. In this paper, we propose Emergency Rescue Urgent Communication -- Evacuation Support System (EUC-ESS) based on Mobile Ad-hoc networks (MANET) composed of many mobile terminals. Using experiments and computer simulations, we show that this system would support evacuators in determining appropriate routes for survivors.

A cognitive radio will have to sense and discover the spectral environments where it would not cause primary radios to interfere. Because the primary radios have the right to use the frequency, the cognitive radios as the secondary radios must detect radio signals before use. However, the secondary radios also need identifying the primary and other secondary radios where the primary radios are vulnerable to interference. In this paper, a method of simultaneously identifying signals of primary and secondary radios is proposed. The proposed bandwidth differentiation assumes the primary and secondary radios use orthogonal frequency division multiplexing (OFDM), and the secondary radios use at the lower number of subcarriers than the primary radios. The false alarm and detection probabilities are analytically evaluated using the characteristic function method. Numerical evaluations are also conducted on the assumption the primary radio is digital terrestrial television broadcasting. Result showed the proposed method could achieve the false alarm probability of 0.1 and the detection probability of 0.9 where the primary and secondary radio powers were 2.5 dB and 3.6 dB higher than the noise power. In the evaluation, the reception signals were averaged over the successive 32 snapshots, and the both the primary and secondary radios used QPSK. The power ratios were 4.7 dB and 8.4 dB where both the primary and secondary radios used 64QAM.

In wireless OFDM systems, the system performance is suffered from frequency offset and symbol timing offset due to the Doppler effect. Using the discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT) for traditional signal transformation from the time-domain into frequency-domain, and vice versa, the system performance may be severely degraded. To make the OFDM system that can tolerate the above problems, we have considered that the harmonic transform can be applicable to the traditional signal transformation, thereby improving the system performance. In this paper, we combine the good characteristics of harmonic transform and instantaneous frequency to be a novel transformation for wireless OFDM systems. We propose a modified discrete harmonic transform (MDHT) which can be performed adaptively. Our proposed scheme called the modified discrete harmonic transform OFDM (MDHT-OFDM scheme). We derive the equations of the novel discrete harmonic transform which are suitable for wireless OFDM systems and the novel channel estimation cooperated with the novel transformation. The proposed channel estimation is performed in both time-domain and frequency-domain. The performance of a MDHT-OFDM scheme is evaluated by means of a simulation. We compare the performance of a MDHT-OFDM scheme with one of the conventional DFT-OFDM scheme in the term of symbol error rate (SER). MDHT-OFDM scheme can achieve better performance than that of the conventional DFT-OFDM scheme in mitigating the Doppler spread.

It is known that wireless ad hoc networks employing omnidirectional communications suffer from poor network throughput due to inefficient spatial reuse. Although the use of directional communications is expected to provide significant improvements in this regard, the lack of efficient mechanisms to deal with deafness and hidden terminal problems makes it difficult to fully explore its benefits. The main contribution of this work is to propose a Medium Access Control (MAC) scheme which aims to lessen the effects of deafness and hidden terminal problems in directional communications without precluding spatial reuse. The simulation results have shown that the proposed directional MAC provides significant throughput improvement over both the IEEE802.11DCF MAC protocol and other prominent directional MAC protocols in both linear and grid topologies.

Electrochromic (EC) type e-paper is attracted with colorfulness and clearness. We have been researching and developing the material for EC type e-paper. We developed novel EC Polymers for e-paper. Our EC polymers are kinds of conductive polymers (CP). CP has some characteristics. One is electrochromism, and the other is electrochemical polymerization. Electrochromism of CP has a good memory effect. And electrochemical polymerization is suitable for printable electronics, for instance, ink-jet, screen print, and so on. Our EC polymers are comprised with thiophene derivatives and pi-conjugated X unit. To our knowledge, this thiophene derivatives are novel structure for EC polymers. These EC polymers have the electrochromic characteristic which change from coloration state to clear state. And we can adjust the color which we want by changing only X unit. And we made segment matrix EC display with our EC polymers by ink-jet printing. Our EC polymers are suitable for printable electronics, flexible substrate, and roll-to-roll process. We introduce our developing technologies.

We consider a distributed transmission of data packet to a sink where the distance of a sensor node to a sink is much longer than the maximum communication range of each sensor node. We give a simple modification to the transmitter, i.e., multiplication of random phase before the transmission. Thanks to Turbo Code, it is possible to extend the transmission range as the received amplitude varies symbol by symbol for our scheme while whole data packet may be lost for the conventional scheme. In this letter, we report the experimental results of our scheme equivalently developed using visible light communication.

The need for efficient movement and precise location of robots in intelligent robot control systems within complex buildings is becoming increasingly important. This paper proposes an indoor positioning and communication platform using Fluorescent Light Communication (FLC) employing a newly developed nine-channel receiver, and discusses a new location estimation method using FLC, that involves a simulation model and coordinate calculation formulae. A series of experiments is performed. Distance errors of less than 25 cm are achieved. The enhanced FLC system yields benefits such as greater precision and ease of use.

This manuscript reported basic examination results of the wireless network communication performance at the coast. We consider that underwater environment condition monitoring is a sort of likely typical application for ubiquitous sensor networks. The result of the experiment shows the performance of the wireless network communication at the coastal area.

The basic requirements of the distributed Web crawling systems are: short download time, low communication overhead and balanced load which largely depends on the systems' Web partition strategies. In this paper, we propose a DHT-based distributed Web crawling system and several DHT-based Web partition methods. First, a new system model based on a DHT method called the Content Addressable Network (CAN) is proposed. Second, based on this model, a network-distance-based Web partition is implemented to reduce the crawler-crawlee network distance in a fully distributed manner. Third, by utilizing the locality on the link space, we propose the concept of link-based Web partition to reduce the communication overhead of the system. This method not only reduces the number of inter-links to be exchanged among the crawlers but also reduces the cost of routing on the DHT overlay. In order to combine the benefits of the above two Web partition methods, we then propose 2 distributed multi-objective Web partition methods. Finally, all the methods we propose in this paper are compared with existing system models in the simulated experiments under different datasets and different system scales. In most cases, the new methods show their superiority.

Two-dimensional (2D) communication is a novel physical communication form that utilizes the surface as a communication medium to provide both data and power transmission service to the sensor devices placed on the surface's top. In previous works, we developed 2D communication systems that utilize separated channels for data and power transmission. Though this assignment of different channels can achieve strong network performance, the sensor devices must be equipped with two or more interfaces to simultaneously receive the power and data signals, which significantly complicates and enlarges those devices. Moreover, when a channel is used for the power supply, it not only continually monopolizes the wireless frequency resource, it is also likely to cause interference with the other signal source in the case of the input power continually being sent out above a certain level. In this paper, we develop a novel 2D communication sensor system by using a single-carrier frequency for both power and data transmission, equipped with the wireless module for the two together in a compact body. To enable a sensor node that concurrently receives energy and data communication, we propose an enhancement scheme based on the IEEE802.15.4 MAC protocol standard. Through both computer simulation and actual measurement of the output power, we evaluate the performance of power supply and data transmission over the developed 2D communication sensor system.