Currently, a correspondent host will have difficulties in establishing a direct session path to a mobile host because of the partial deployment of MIPv6-aware mobile hosts. Even MIPv6-aware hosts will spend up to several seconds to obtain the new location of the mobile host during Layer 3 (L3) handover. This paper proposes an application-level mobility management scheme that can solve the problems related to the increase of Internet traffic end-to-end delay under the current situation that most of the mobile devices are MIPv6-non-aware. The proposed Secure Mobility Management Application (SMMA) enables the updates of care-of address to be faster and more reliable even when L3 handovers occur frequently. SMMA uses a cross-layer approach for session mobility management with the support of Binding Updates to the home agent via IPSec tunnels. The main feature of SMMA is to handle the session-related mobility management for which operation starts just after the completion of name resolution as a pre-call mobility management, which operates in conjunction with the DNS. Our session-related mobility management introduces three new signaling messages: SS-Create for session state creation, SS-Refresh for session state extension and SS-Renewal for updating new care-of address at the mid-session. Finally, this paper analyzes the work load imposed on a mobile host to create a session state and the security strength of the SS-Renewal message, which depends on the key size used.

In this invited paper, software defined network (SDN)-based approaches for future cost-effective optical mobile backhaul (MBH) networks are discussed, focusing on key principles, throughput optimization and dynamic service provisioning as its use cases. We propose a novel physical-layer aware throughput optimization algorithm that confirms > 100Mb/s end-to-end per-cell throughputs with ≥2.5Gb/s optical links deployed at legacy cell sites. We also demonstrate the first optical line terminal (OLT)-side optical Nyquist filtering of legacy 10G on-off-keying (OOK) signals, enabling dynamic >10Gb/s Orthogonal Frequency Domain Multiple Access (OFDMA) λ-overlays for MBH over passive optical network (PON) with 40-km transmission distances and 1:128 splitting ratios, without any ONU-side equipment upgrades. The software defined flexible optical access network architecture described in this paper is thus highly promising for future MBH networks.

Many detailed studies ranging from networking to hardware as well as standardization activities over the last few years have advanced the performance of the elastic optical network. Thanks to these intensive works, the elastic optical network has been becoming feasible. This paper reviews the recent advances in the elastic optical network from the aspects of networking technology and hardware design. For the former, we focus on the efficient elastic network design technology related to routing and spectrum assignment (RSA) of elastic optical paths including network optimization or standardization activities, and for the latter, two key enabling technologies are discussed: elastic transponders/regenerators and gridless optical switches. Making closely-dependent networking and hardware technologies work synergistically is the key factor in implementing truly effective elastic optical networks.

This paper proposes a simple and practical scheme to decide the direction of a phased array antenna beam in wireless access systems using Radio-over-Fiber (RoF) technique. The feasibility of the proposed scheme is confirmed by the optical and wireless transmission experiments using 2GHz RoF signals. In addition, two-dimensional steering operation in the millimeter-wave band is demonstrated for targeting future high-speed wireless communication systems. The required system parameters for practical use are also provided by investigating the induced transmission penalties. The proposed detection scheme is applicable to two-dimensional antenna beam steering in the millimeter-wave band by properly designing the fiber length and wavelength variable range.

Triggered by the Great East Japan Earthquake in March 2011, the authors have been studying a resilient network whose key element is a movable and deployable ICT resource unit. The resilient network needs a function of robust and immediate connection to a wide area network active outside the damaged area. This paper proposes an application of digital coherent technology for establishing optical interconnection between the movable ICT resource unit and existing network nodes through a photonic network, rapidly, easily and with the minimum in manual work. We develop a prototype of a 100Gbit/s digital coherent transponder which is installable to our movable and deployable ICT resource unit and experimentally confirm the robust and immediate connection by virtue of the plug and play function.

This paper presents a novel decoupling network consisting of transmission lines and a bridge resistance for a two-element array antenna and evaluates its performance through simulations and measurements. To decouple the antennas, the phase of the mutual admittance between the antenna ports is rotated by using the transmission lines, and a pure resistance working as a bridge resistance is inserted between the two antenna ports to cancel the mutual coupling. The simulation results indicate that the proposed decoupling network can provide a wider bandwidth than the conventional approach. The proposed decoupling network is implemented and tested as a demonstration to confirm its performance. The measurement results indicate that the mutual coupling between the two antenna ports is lowered by about 47dB at the resonant frequency.

The effect of transceiver impairments (consisting of frequency offset, phase noise and doubly-selective channel) is a key factor for determining performance of an orthogonal frequency-division multiplexing (OFDM) system since the transceiver impairments trigger intercarrier interference (ICI). These impairments are well known and have been investigated separately in the past. However, these impairments usually arise concurrently and should be jointly considered from the perspectives of both receiver design and system evaluation. In this research, impact of these impairments on an OFDM system is jointly analyzed and the result degenerates to the special case where only a specific impairment is present. A mitigation method aided by segment-by-segment time-domain interpolation (STI) is then proposed following the analysis. STI is general, and its weights can be specified according to the interpolation method and system requirements. Computer simulation is used to validate the analysis and to compare the performance of the proposed method with those of other proposals.

Single Carrier — Frequency Domain Multiple Access (SC-FDMA) is a multiple access technique employed in LTE uplink transmission. SC-FDMA can improve system throughput by frequency selective scheduling (FSS). In cellular systems using SC-FDMA in the uplink, interference arising from user equipments (UEs) in neighboring cells degrades the system throughput, especially the throughput of cell-edge UEs. In order to overcome this drawback, many papers have considered fractional frequency reuse (FFR) techniques and analyzed their effectiveness. However, these studies have come to different conclusions regarding the effectiveness of FFR because the throughput gain of FFR depends on the frequency reuse design and evaluation conditions. Previous papers have focused on the frequency reuse design. Few papers have examined the conditions where FFR is effective, and only the UE traffic conditions have been evaluated. This paper reveals other conditions where FFR is effective by demonstrating the throughput gain of FFR. In order to analyze the throughput gain of FFR, we focus on the throughput relationship between FFR and FSS. System level simulation results demonstrate that FFR is effective when the following conditions are met: (i) the number of UEs is small and (ii) the multipath delay spread is large or close to 0.

We experimentally demonstrate an optical packet and circuit integrated (OPCI) ring network interoperated with a wavelength-switched optical network (WSON) in a network domain. OPCI network and WSON have distinct characteristics from each other: the methods to transfer path control messages and the protocols to set up or delete the optical connections in an optical circuit switch. To interoperate the two types of optical networks, we develop a common path control-plane which can establish or release an end-to-end path by only one autonomous distributed signaling process without stitching. In the common path control-plane, we modify the signaling protocol for OCS so that we can allocate a distinct wavelength to each link on an end-to-end path and also allocate a distinct path route to each of downstream and upstream directions in a bi-directional path. We experimentally show that the common path control-plane can dynamically establish end-to-end paths over the heterogeneous network including the two types of optical networks.

We fabricated high-quality domain-inverted MgO: LiNbO$_3$ structures with 3.0 and 2.0~$mu$m periods using applying votage to the corrugation electrode. We found that keeping the crystal temperature at 150$^{circ}$C for 12 hours before applying voltage was effective for obtaining good uniformity. We also demonstrated an application of the structures with 3.0~$mu$m period to electro-optic Bragg deflection modulator for the first time.

We demonstrate an all-optical non-return-to-zero differential phase shift keying (NRZ-DPSK) to return-to-zero differential phase shift keying (RZ-DPSK) format conversion with wavelength-shift-free and pulsewidth tunable operations by using a semiconductor optical amplifier (SOA)-based switch. An NRZ-DPSK signal is injected into the SOA-based switch with an RZ clock, and is converted to RZ-DPSK signal owing to the nonlinear effects inside the SOA. In this scheme, the wavelength of the converted RZ-DPSK signal is maintained as the original wavelength of the input NRZ-DPSK signal during the format conversion. Moreover, the pulsewidth of the converted signal is tunable in a wider operating range from 30 to 60 ps. The format conversion with pulsewidth tunability is based on cross-phase modulation (XPM) and cross-gain modulation (XGM) effects in the SOA. The clear eye diagrams, optical spectra and the bit-error-rate (BER) characteristics show high conversion performance with the wide pulsewidth tuning range. For all cases of the converted RZ-DPSK signal with different pulsewidths, the receiver sensitivities at a BER of 10$^{-9}$ for the converted RZ-DPSK signal were 0.7 to 1.5 dB higher than the receiver sensitivity of the input NRZ-DPSK signal.

We investigate resolution improvement in optical quantization with keeping high sampling rate performance in optical sampling. Since our optical quantization approach uses power-to-wavelength conversion based on soliton self-frequency shift, a spectral compression can improve resolution in exchange for sampling rate degradation. In this work, we propose a different approach for resolution improvement by parallel use of dispersion devices so as to avoid sampling rate degradation. Additional use of different dispersion devices can assist the wavelength separation ability of an original dispersion device. We demonstrate the principle of resolution improvement in 3 bit optical quantization. Simulation results based on experimental evaluation of 3 bit optical quantization system shows 4 bit optical quantization is achieved by parallel use of dispersion devices in 3 bit optical quantization system. The maximum differential non-linearity (DNL) and integral non-linearity (INL) are 0.49 least significant bit (LSB) and 0.50 LSB, respectively. The effective number of bits (ENOB) estimated to 3.62 bit.

Classification tasks in computer vision and brain-computer interface research have presented several applications such as biometrics and cognitive training. However, like in any other discipline, determining suitable representation of data has been challenging, and recent approaches have deviated from the familiar form of one vector for each data sample. This paper considers a kernel between vector sets, the mean polynomial kernel, motivated by recent studies where data are approximated by linear subspaces, in particular, methods that were formulated on Grassmann manifolds. This kernel takes a more general approach given that it can also support input data that can be modeled as a vector sequence, and not necessarily requiring it to be a linear subspace. We discuss how the kernel can be associated with the Projection kernel, a Grassmann kernel. Experimental results using face image sequences and physiological signal data show that the mean polynomial kernel surpasses existing subspace-based methods on Grassmann manifolds in terms of predictive performance and efficiency.

With the advances in wireless Internet and mobile positioning technology, location-based services (LBSs) have become popular. In LBSs, users must send their exact locations in order to use the services, but they may be subject to several privacy threats. To solve this problem, query processing algorithms based on a cloaking method have been proposed. The algorithms use spatial cloaking methods to blur the user's exact location in a region satisfying the required privacy threshold (k). With the cloaked region, an LBS server can execute a spatial query processing algorithm preserving their privacy. However, the existing algorithms cannot provide good query processing performance. To resolve this problem, we, in this paper, propose a k-NN query processing algorithm based on network Voronoi diagram for spatial networks. Therefore, our algorithm can reduce network expansion overhead and share the information of the expanded road network. In order to demonstrate the efficiency of our algorithms, we have conducted extensive performance evaluations. The results show that our algorithm achieves better performance on retrieval time than the existing algorithms, such as PSNN and kRNN. This is because our k-NN query processing algorithm can greatly reduce a network expansion cost for retrieving k POIs.

In recent years, computation offloading, through which applications on a mobile device can offload their computations onto more resource-rich clouds, has emerged as a promising technique to reduce battery consumption as well as augment the devices' limited computation and memory capabilities. In order for computation offloading to be energy-efficient, an accurate estimate of battery consumption is required to decide between local processing and computation offloading. In this paper, we propose a novel technique for estimating battery consumption without requiring detailed information about the mobile application's internal structure or its execution behavior. In our approach, the relationship is derived between variables that affect battery consumption (i.e., the input to the application, the transmitted data, and resource status) and the actual consumed energy from the application's past run history. We evaluated the performance of the proposed technique using two different types of mobile applications over different wireless network environments such as 3G, Wi-Fi, and LTE. The experimental results show that our technique can provide tolerable estimation accuracy and thus make correct decisions between local processing and computation offloading.

In this work, a gate-all-around (GAA) tunneling field-effect transistor (TFET) with InGaAs/Si heterojunction for high-performance and low-standby power operations is studied. Gallium (Ga) compositon ($x)$ in In$_{1-x}$Ga$_{x}$As source substantially affects the physical properties related with device performances including lattice constant, bandgap energy, effective tunneling mass, channel mobility, and others. Thus, it is worthy investigating the effect of Ga fraction on performances of the proposed heterojunction TFET. For this goal, the device design and its performance evaluation are carried out by technology computer-aided design (TCAD). Direct-current (DC) performances are investigated in terms of on-state current ($I_{ m{on}})$, off-state current ($I_{ m{off}})$, current ratio ($I_{ m{on}}$/$I_{ m{off}})$, and subthreshold swing ($S$). Furthermore, it is shown that the device with an n-type Si insertion layer between source and channel demonstrates the enhanced DC characteristics.

An optoelectronic 32-bit serial-to-parallel converter with a novel conversion scheme and shared-trigger configuration has been developed for the label processing of 100-Gbps (25-Gbps $ imes 4 lambda)$ optical packets. No external optical trigger source is required to operate the converter, as the optical packet itself is used to perform self-triggering. Compared to prior optoelectronic label converters, the new device has a much higher gain even while converting labels at higher data rates, and exhibits tolerance to the voltage swing of received packets. The device response is presented together with the experimental demonstration of serial-to-parallel conversion for 4 different labels at 25 Gbps.

Graphene is attracting attention in electrical and optical research fields recently. We measured the optical absorption characteristics and polarization dependence of single-layer graphene (SLG) on sub-micrometer Si waveguide. The results for graphene lengths ranging from 2.5 to 200 $mu$ m reveal that the optical absorption by graphene is 0.09 dB/$mu$ m with the TE mode and 0.05 dB/$mu$ m with the TM mode. The absorption in the TE mode is 1.8 times higher than that in the TM mode. An optical spectrum, theoretical analysis and Raman spectrum indicate that surface-plasmon polaritons in graphene support TM mode light propagation.

The past decade has witnessed a growing interest in vehicular networking. Initially motivated by traffic safety, vehicles equipped with computing, communication and sensing capabilities will be organized into ubiquitous and pervasive networks with a significant Internet presence while on the move. Large amount of data can be generated, collected, and processed on the vehicular networks. Big data on vehicular networks include useful and sensitive information which could be exploited by malicious intruders. But intrusion detection in vehicular networks is challenging because of its unique features of vehicular networks: short range wireless communication, large amount of nodes, and high mobility of nodes. Traditional methods are hard to detect intrusion in such sophisticated environment, especially when the attack pattern is unknown, therefore, it can result unacceptable false negative error rates. As a novel attempt, the main goal of this research is to apply data mining methodology to recognize known attacks and uncover unknown attacks in vehicular networks. We are the first to attempt to adapt data mining method for intrusion detection in vehicular networks. The main contributions include: 1) specially design a decentralized vehicle networks that provide scalable communication and data availability about network status; 2) applying two data mining models to show feasibility of automated intrusion detection system in vehicular networks; 3) find the detection patterns of unknown intrusions.

Blur distortion is a common artifact in image communication and affects the perceived sharpness of a digital image. In this paper, we capitalize on the mathematical knowledge of Gaussian convolution and propose a strategy to minimally reblur test images. From the reblur algorithm, synthetic reblur images are created. We propose a new blind blur metric which makes use of the reblur images to produce blur scores. Compared to other no-reference blur assessments, the proposed method has the advantages of fast computation and training-free operation. Experiment results also show that the proposed method can produce blur scores which are highly correlated with human perception of blurriness.