We experimentally demonstrated polarization-mode dispersion (PMD) compensation by distributing polarizers with only 1 degree of freedom (DOF) along the transmission line. The average power penalty was measured to be 0.4 dB by inserting four compensators, where average differential group delay was 47% of bit period.

We propose a new label recognition system for photonic label routing network. Binary-coded labels in binary phase-shift-keying format are considered. The system consists of an optical waveguide circuit with tree-structure passive asymmetric X-junctions and time gates. The system uses self-routing propagation of an identifying bit by performing interference with address bits. The identifying bit is placed in advance of the address bits in the label. The identifying bit pulse is routed to the destination output port corresponding to the code of the address. The operation principle is described. It is shown that all the binary number codes can be recognized with this system. We discuss the feasibility of the system by evaluating its crosstalk. To reduce the crosstalk, an improved scheme is also presented. The label recognition operation with the optical waveguide device is verified by numerical simulation using the finite-difference beam propagation method.

Optical wireless communications is a research topic of extreme interest since it offers high data rate (Gbps data rate), security, and RF interference immunity. However, optical wireless communications places severe restrictions on the communications paths; they must be direct beam connections. To increase the number of users and link robustness, optical wireless communications must be able to operate even when obstacles are placed between transmitters and receivers, so optical micro-cell (OMC) with autonomous beam control can overcome link robustness. In addition, OMC based optical wireless communication yields compact systems. This paper presents the design, an implementation, and a demonstration of a 114 Mbps autonomous beam control optical wireless communication system based on an OMC technique. The robust posture control results optimum downlink alignment and good eye diagram of data transmission.

Transmit diversity gain can be obtained in cooperative communication by cooperating the multiple users with single antenna. In cooperative communication, in the first step, each mobile station (MS) transmits its own data to both the base station (BS) and the other MS. In the second step, each MS's data is transmitted from the other MS to BS. As a result, transmit diversity gain can be obtained without implementing multiple transmit antennas at MS. In the conventional relay method, if error is detected within the received packet by using cyclic redundancy check (CRC) code, MS transmits its own data to BS instead of relaying the other MS's data in the second step. As a result, transmit diversity gain cannot be obtained. In this paper, we propose a novel cooperative method. In the proposed method, if the CRC decoder detects error within the received packet, MS transmits soft decision symbol which is obtained from the decoded data in second step. As a result, the transmit diversity gain always can be obtained. From the computer simulation, we show that the proposed method can achieve the better error rate performance than the conventional one.

It is well known that Pisarenko's frequency estimate for a single real tone can be computed easily using the sample covariance with lags 1 and 2. In this Letter, we propose to use alternative covariance expressions, which are inspired from the modified covariance (MC) frequency estimator, in Pisarenko's algorithm. Computer simulations are included to corroborate the theoretical development of the variant and to demonstrate its superiority over the MC and Pisarenko's methods.

A stacked rectangular microstrip antenna with a shorting plate is proposed as a car antenna for dual band (VICS and ETC) operation in the ITS. The proposed antenna has the proper radiation patterns for the VICS and ETC. The antenna is small in size and effective in dual band operation.

This paper describes near-zero ultra-flattened chromatic dispersion and low confinement loss that can be achieved from a decagonal photonic crystal fiber (D-PCF). The finite difference method with anisotropic perfectly matched boundary layer (PML) is used for the numerical analysis. It is demonstrated that it is possible to design a four-ring D-PCF with ultra-flattened dispersion of 0 0.69 ps/(nm-km) in a 1.30 to 1.75 µm wavelength range and 0 0.22 ps/(nm-km) in a 1.35 to 1.65 µm wavelength range with very low confinement losses of order 0.0011 dB/km. The proposed D-PCF shows promising dispersion tolerance.

In this paper, we describe a new ultrasonic oscillosensor and its application in a biological information measurement system. This ultrasonic sensor has a cylindrical tank of 26 mm (diameter)20 mm (height) filled with water and an ultrasonic probe. It detects the vibration of the target object by obtaining echo signals reflected from the water surface. This sensor can noninvasively detect the vibration of a patient by placing it under a bed frame. We propose a recognition system for humans in bed. Using this sensor, we could determine whether or not a patient is in the bed. Moreover, we propose a heart rate monitoring system using this sensor. When our system was tested on four volunteers, we successfully detected a heart rate comparable to that in the case of using an electrocardiograph. Fuzzy logic plays a primary role in the recognition. Consequently, this system can noninvasively determine whether a patient is in the bed as well as their heart rate using a constraint-free and compact device.

This paper presents media processor architectures for automotive applications. Media processing applications with their requirements for LSI implementations are first described for vision based driver assistance as well as graphical user interface for car navigation using 3D graphics. Then, parallel processing architectures for vision and graphics in these applications are reviewed with their performance and cost. After that, future trends of automotive media processing such as integration of vision and 3D graphics functions are shown with their applications and the required performance. Moreover, parallel processing architectures are discussed for the integration of vision and graphics. Finally, an prospect of a next-generation media processing LSI for automotives is provided.

In mobile ad hoc networks, as the communications have to be achieved autonomously and via third parties, a variety of risks against stable communication and session completion can be predicted. Many researchers have been studying these issues, i.e., mobility, broadcast storm, selfish behavior on data forwarding, security, and so forth. However, availability of routes against selfish power off is still to be addressed. This paper defines a new, realistic and practical problem beyond the scope of malicious program modification, called selfish power off, and evaluates the influence of it. Here, a selfish user turns his terminal on only when it has some data to send or receive and decline to work as an intermediate user by turning its terminal power off. In addition, this paper proposes a solution, called Proactive COoperation Mechanism (PCOM) against selfish power off in order to eliminate the influence of selfish power off. In PCOM, each user holds the cooperation records of its adjacent users, and forwards only those packets that are generated by users with good cooperation records. PCOM thus prevents SUs from joining the network. Extensive simulation shows the efficiency of our proposal in maintaining network connectivity and fairness in resource consumption.

Radio communications via channels already occupied by traditional telecommunication systems can be achieved by using ultra-wideband (UWB) radio where extremely wideband wavelets are used in order to reduce the power spectral density (psd) of transmitted signal. Since the recovery of these UWB carriers is not feasible, noncoherent demodulation techniques have to be used. The letter evaluates and compares the noise performances of the feasible noncoherent UWB modulation schemes, namely, that of the noncoherent pulse polarity modulation and the transmitted reference system.

This paper presents efficient applications of invariants to harmonic balance (HB) methods using Grobner base. The Grobner base is a powerful tool based on ideal theory. Using the Grobner base, we can obtain the solutions of the HB equation. However, its computation is very time-consuming when the equation has equivalent different solutions based on symmetries of the system. We show that invariants enable to transpose the equivalent different solutions to a unique solution. The bifurcation diagram of the invariant is simpler than the original bifurcation diagram, and its computation is considerably decreased. Further, we can obtain the relation among the amplitudes of each frequency component using the invariants. We propose a method for finding the circuit parameters using the amplitude relation.

In this paper, we propose an intrablog-based informal communication encouraging system named "Attractiblog." It has been pointed out that daily informal communications at a shared public space play very important role in information sharing in an organization. However, in most cases, the communications are often mere chats. To make the communications more informative, it is necessary to feed some common and beneficial topics there. Attractiblog is a system that extracts some articles posted in an intrablog considering who are in the shared space, and show them on a large-sized display that is located in the space. Thus, Attractiblog attempts to seamlessly link on-line communications to off-line communications. We conducted user studies and confirmed that Attractiblog can achieve a natural correspondence between topics in face-to-face informal communications and issues related to the activities of an organization as given in its intrablog.

Monotonic condition, a well-known sufficient condition for Schur stability of real polynomials, is relaxed. The condition reads that a series of strictly and monotonically decreasing positive coefficients of the polynomials yields Schur stability. It is shown by inspecting the original proof that equalities are allowed in all the inequalities but two which are located at appropriate positions.

We achieved the first 10 Gb/s WDM transmission at 1064 and 1550 nm over 24 km of photonic crystal fiber (PCF). We confirmed an improvement in the bit error rate (BER) performance after the transmission, namely "negative power penalties" of -0.5 and -0.3 dB at 1064 and 1550 nm, respectively. Our experimental result and theoretical estimation revealed that the signal degradation induced by the chromatic dispersion can be effectively suppressed by employing the pre-chirp technique with a conventional Z-cut lithium niobate (LN) modulator. We also show theoretically that we can expect to realize 10 Gb/s transmission over a 24 km PCF with negligible BER degradation in the 1060 to 1600 nm wavelength range by using the pre-chirp technique.

A chaotic UWB communication system based on IEEE 802.15.4a is proposed for wireless connectivity applications. A compact and simple architecture is implemented by using a chaotic UWB signal and a non-coherent detection scheme. The chaotic UWB signal has noise-like characteristics in time and frequency domains and naturally wide spectrum within a limited bandwidth. The chaotic UWB signal generator is designed on two methods with the bandwidth of 3.1 to 5.1 GHz, and a baseband process is realized on an FPGA including an adaptive decision and a channel code for non-source coded data stream. The system performance is evaluated by transmitting MP3 audio/voice with 32-byte length PSDUs and measuring PERs for assessing the system sensitivity and the interferer compatibility. The proposed system can be an excellent candidate for short-range connectivity services, as well as an inexpensive system with good capability for narrow-band interferences.

This paper clarifies the sideband suppression ratio (SSR) value needed for multi-carrier signal modulation in an optical single sideband (SSB) modulator. An SSR value of about 25 dB is found to be sufficient for broadcast satellite (BS) multi-carrier signal modulation. For FM converted CATV signal modulation, an SSR value of about 10 dB is sufficient. In addition, the properties of cascaded lithium niobate Mach-Zehndar (LN MZ) optical SSB modulators are clarified to be better than those of the conventional single LN MZ optical SSB modulator with nearly the same SSR value of 27 dB.

Reliable Multicast has been applied to large-scale contents delivery systems for distributing digital contents to a large number of users without data loss. Reliable contents distribution is indispensable for software updates and management data sharing in actual delivery services. This paper evaluates the implementation and performance of RMTP; a reliable multicast protocol for bulk-data transfer, through the developments of contents delivery systems. Software configuration is also examined including operation functions such as delivery scheduling. Furthermore, applicability of reliable multicast to emerging broadband networks is also discussed based on the experimentation results. Through the deployment of the protocol and the software, performance estimation has played a key role for constructing the delivery systems as well as for designing the communication protocol.

A comparison among the possible nonlinear photonic interactions for scalable nanometer networks and quantum gates as well as for coherence retention in solids is made theoretically, and then numerical plottings are given, on the basis of the dipole length estimated from our µ-PL (microphotoluminescence) spectra of GaAs/AlGaAs coupled quantum dots (QDs) having a pair of 0.3 meV splittings. Furthermore, prospective device concepts based on these nonlinear multipolar interactions are given.

Due to the discontinuity of packet based traffic, the user terminals in next generation mobile telecommunications systems will be equipped with sleep mode operation functions for power saving purpose. The sleep mode parameters should be appropriately configured so that power consumption can be sufficiently decreased while packet queue length and packet delay are restricted within a demanded level. This paper proposes an adaptive sleep mode parameter configuration scheme which is able to jointly optimize the inactivity timer and sleep period in response to the variation of user traffic arrival pattern. The optimization target of this scheme is to minimize mobile terminal power consumption while ensuring that the mean downlink packet queue length do not exceed a certain threshold. Results of computer simulations prove that, the presented approach perfectly manages packet queue length restriction, packet delay control and power saving in a wide range of user packet inter-arrival rates both in single- and dual-service scenarios.