This letter describes combining OSGi and Web Services in service composition. According to our approach, a composite service is described in WS-BPEL. Each component service in the description may be resolved to either an OSGi service or Web Service at runtime. The proposal can overcome current limitations with OSGi technology in terms of its geographical coverage and candidate service population available for service composition.

Fair allocation of bandwidth and maximization of channel utilization are two important issues when designing a contention-based wireless medium access control (MAC) protocol. However, fulfilling both design goals at the same time is very difficult. Considering the problem in the IEEE 802.11 wireless local area networks (WLANs), in this work we propose a method using a p-persistent enhanced DCF, called P-IEEE 802.11 DCF, to achieve weighted fairness and efficient channel utilization among multiple priority classes in a WLAN. Its key idea is that when the back-off timer of a node reaches zero, the transmission probability is properly controlled to reflect the relative weights among data traffic flows so as to maximize the aggregate throughput and to minimize the frame delay at the same time. In particular, we obtain the optimal transmission probability based on a theoretical analysis, and also provide an approximation to this probability. The derived optimal and approximation are all evaluated numerically and simulated with different scenarios. The results show that the proposed method can fulfill our design goals under different numbers of priority classes and different numbers of nodes.

In this letter, we propose a new power allocation scheme for random unitary beamforming assuming a discrete transmission rate with a small amount of feedback information and low latency. Simulation results show that the proposed scheme can improve throughput compared to the conventional power allocation scheme.

In this paper, we propose a novel multiuser detection (MUD) method that is robust against timing offset between wireless terminals (WTs) for the multiuser multiple-input multiple-output (MU-MIMO) orthogonal frequency division multiplexing (OFDM) uplink. In the proposed method, MUD is carried out in the frequency-domain using overlapping fast Fourier transform (FFT) windows. After the inverse FFT (IFFT) operation, the samples obtained at both ends of each FFT window are discarded to suppress the effect of inter-block interference (IBI). Thus, it realizes an MUD regardless of the arrival timing differences of the signals from the WTs. The achievable bit error rate (BER) performance of the proposed MUD method is evaluated by computer simulations in a frequency selective fading channel.

This paper proposes a novel service configuration approach that can realize dynamic critical Quality of Service (QoS) adaptation to ever-changing and resource-limited ubiquitous computing environments. In the approach, service configuration is reduced to a Fuzzy Control System (FCS) which aims to achieve critical QoS variations on minimal level with less power cost. Two configuration strategies, service chain reconfiguration and QoS parameters adjustment, along with a configuration algorithm, are implemented to handle different types of QoS variations. A self-optimizing algorithm is designed to enhance the adaptation of the FCS. Simulation results validate the proposed approach.

With the growth of the Internet, various types of services are rapidly expanding; such services include the World Wide Web (WWW), the File Transfer Protocol (FTP), and remote login. Consequently, managing authentication information, e.g., user ID/password pairs, keys, and certificates- is difficult for users, since the amount of required authentication information has been increased. To address this problem, researchers have developed a Single Sign-On (SSO) system that makes all the services available for a user via a one-time authentication: however, existing authentication systems cannot provide such SSO services for all kind of services on the Internet, even if the service provider deploys the SSO server. Further, existing systems also cannot provide the SSO service which does not make it conscious of a network domain to a user on secure network environment. Therefore, in this paper, we propose a new SSO system with a hardware token and a key management server to improve the safety, ubiquity, and adaptability of services. Further, we implement the proposed system and show its effectiveness through evaluation. Adding any functions for this system provides various conveniences to us. We also explore the ability to add functions to this system; for example, we add high trust connection functionality for a Web server and show its effectiveness.

The capacity of multiuser OFDM systems can be maximized by allocating resources (subcarrier and power) to the user with the highest instantaneous channel gain. This assumes complete channel state information (CSI) at the transmitter, which is achieved by every user reporting its CSI for all subcarriers to the transmitter via feedback channel. In practice, due to the limited capacity of the feedback channel, the completeness of CSI may be severely restricted especially with a large number of users transmitting a large amount of feedback information. In order to reduce the amount of feedback information while preserving the maximal capacity, quality based CSI feedback (QCF) is proposed in this letter. The system capacity is derived with QCF and compared with that of full CSI feedback. The results show that QCF successfully reduces the amount of feedback information with little capacity loss.

Due to the fast development of Internet and the related IT technologies, it becomes more and more easier to access a large amount of data. k-means clustering is a powerful and frequently used technique in data mining. Many research papers about privacy-preserving k-means clustering were published. In this paper, we analyze the existing privacy-preserving k-means clustering schemes based on the cryptographic techniques. We show those schemes will cause the privacy breach and cannot output the correct results due to the faults in the protocol construction. Furthermore, we analyze our proposal as an option to improve such problems but with intermediate information breach during the computation.

Privacy preserving is indispensable in data mining. In this paper, we present a novel clustering method for distributed multi-party data sets using orthogonal transformation and data randomization techniques. Our method can not only protect privacy in face of collusion, but also achieve a higher level of accuracy compared to the existing methods.

In this study, a performance isolation mechanism based on a fuzzy control technique is developed in such a way that ambiguous situations caused when estimating the workload of cluster-based web servers, client request rates, and dynamic request rates can be represented effectively. The proposed mechanism involving a fuzzy-based technique is compared with a non-fuzzy technique in terms of the response time in the 95th percentile. Experiments showed that the proposed technique improves the performance of web servers that provide differentiated services.

To develop a network management system (NMS) more easily, the authors developed an application programming interface (API) for configuring network devices. Because this API is used in a Java development environment, an NMS can be developed by utilizing the API and other commonly available Java libraries. It is thus possible to easily develop an NMS that is highly compatible with other IT systems. And operations that are generated from the API and that are exchanged between the NMS and network devices are based on NETCONF, which is standardized by the Internet Engineering Task Force (IETF) as a next-generation network-configuration protocol. Adopting a standardized technology ensures that the NMS developed by using the API can manage network devices provided from multi-vendors in a unified manner. Furthermore, the configuration items exchanged over NETCONF are specified in an object-oriented design. They are therefore easier to manage than such items in the Management Information Base (MIB), which is defined as data to be managed by the Simple Network Management Protocol (SNMP). We actually developed several NMSs by using the API. Evaluation of these NMSs showed that, in terms of configuration time and development time, the NMS developed by using the API performed as well as NMSs developed by using a command line interface (CLI) and SNMP. The NMS developed by using the API showed feasibility to achieve "autonomic network management" and "high interoperability with IT systems."

In this letter, a new joint precoding and decoding design scheme for multiuser MIMO downlink is proposed which dispenses with iterative operations and can achieve better performance. This scheme introduces zero-force processing into minimum mean square error (MMSE) design scheme to avoid iterative operations. We derived closed-form precoders and decoders and transmit power allocation strategy of proposed design scheme, validated performance of proposed design scheme by computer simulation. The simulation results show that the proposed design scheme can achieve better bit error rate (BER) and sum capacity performance compared to an existing non-iterative design scheme.

Cooperative transmission is an efficient approach to improve the performance of wireless communications over fading channels without the need for physical co-located antenna arrays. In this paper, we propose a novel cooperative protocol with selective decode-and-forward relays and generalized selection combining (GSC) technique at destination. The advantage of this scheme is that it not only allows us to optimize the structure of destination but also to fully exploit the diversity offered by the channels with an appropriate number of chosen strongest paths. For an arbitrary number of relays, an exact and closed-form expression of the Symbol Error Rate (SER) is derived for M-ary PSK in independent but not identically distributed Rayleigh fading channels. Various simulations are performed and their results exactly match the results of analyses.

This paper proposes a point-to-multipoint (P2MP) Multi-Protocol Label Switching (MPLS) based hierarchical service management system. Traditionally, general management systems deployed in some service providers control MPLS Label Switched Paths (LSPs) (e.g., RSVP-TE and LDP) and services (e.g., L2VPN, L3VPN and IP) separately. In order for dedicated management systems for MPLS LSPs and services to cooperate with each other automatically, a hierarchical service management system has been proposed with the main focus on point-to-point (P2P) TE LSPs in MPLS path management. In the case where P2MP TE LSPs and services are deployed in MPLS networks, the dedicated management systems for P2MP TE LSPs and services must work together automatically. Therefore, this paper proposes a new algorithm that uses a correlation between P2MP TE LSPs and multicast VPN services based on a P2MP MPLS-based hierarchical service management architecture. Also, the capacity and performance of the proposed algorithm are evaluated by simulations, which are actually based on certain real MPLS production networks, and are compared to that of the algorithm for P2P TE LSPs. Results show this system is very scalable within real MPLS production networks. This system, with the automatic correlation, appears to be deployable in real MPLS production networks.

In general-synchronous framework, in which the clock is distributed periodically to each register but not necessarily simultaneously, the circuit performance such as the clock period is expected to be improved by delay insertion. However, if the amount of inserted delays is too much, then the circuit is changed too much and the circuit performance might not be improved. In this paper, we propose an efficient delay insertion method that minimizes the amount of inserted delays in the clock period improvement in general-synchronous framework. In the proposed method, the amount of inserted delays is minimized by using an appropriate clock schedule and by inserting delays into appropriate places in the circuit. Experiments show that the proposed method can obtain optimum solutions in short time in many cases.

We describe a channel-vector quantization scheme that is suitable for multiple stream transmission per user in zero-forcing beamforming (ZFBF) multiuser multiple-input and multiple output (MU-MIMO) systems with finite rate feedback. Multiple subsets of a channel matrix are quantized to vectors from random vector codebooks for finite rate feedback. The quantization vectors with an angle difference that is closer to orthogonal are then selected and their indexes are fed back to the transmitter. Simulation results demonstrate that the proposed scheme achieves a better average throughput than that serving a single stream per user when the number of active users is smaller than the number of transmit antennas and that it provides an average throughput close to that serving a single stream per user when the number of users is equal to the number of transmit antennas.

A CMOS current-mode companding divider is presented. Currents of both dividend and divisor are compressed into log-domain. Then the logarithm current of divisor is subtracted from the logarithm current of dividend. After expanding the subtraction result, the division function could be achieved. The simulation results indicate that the proposed divider has with good performance at only 1.8 V supply voltage.

The Processing of high-dynamic-range (HDR) images is embodied by a lot of algorithms. This paper takes notice of one of these algorithms which is presented using the iCAM06. iCAM06 is capable of making color appearance predictions of HDR images based on CIECAM02 color predictions and incorporating spatial process models in the human visual system (HVS) for contrast enhancement. The effect of user controllable factors of iCAM06 was investigated and the best factor which corresponds with Breneman's corresponding color data sets was found. A suggested model improves color matching predictions for the corresponding color data set in Breneman's experiment.

The authors propose a user-centric seamless handover (HO) scheme, which is a kind of a vertical HO from a new perspective, toward a next generation network where heterogeneous access networks converge. The users' experience-oriented scheme allows users to enjoy the optimal service quality for real-time applications in respective access networks. In addition, the scheme sustains on-going sessions during the vertical HO. The proposed scheme consists of two methods -- the bicasting of Different Quality-level Streams (DiffQS) and the Delay Difference Absorption (DDA) method. Initially, the authors propose two plausible methods for the SIP-based bicasting of DiffQS. This document introduces a SIP-capable network element named the HO Assistive Server (HOAS). HOAS controls bicasting of DiffQS and provides users with the optimal service quality for real-time applications via respective access networks as well as avoiding packet loss during HO. The DDA method is also proposed to prevent a service interruption and smoothly continue a real-time service during HO. Evaluation results show that the scheme achieves the seamless service continuity from the users' perspective for HO between cellular and high-speed wireless access via the implementation of a prototype system.

We have proposed and successfully demonstrated a two step method for localizing defects on an LSI chip. The first step is the same as a conventional laser-SQUID (L-SQUID) imaging where a SQUID and a laser beam are fixed during LSI chip scanning. The second step is a new L-SQUID imaging where a laser beam is stayed at the point, located in the first step results, during SQUID scanning. In the second step, a SQUID size (Aeff) and the distance between the SQUID and the LSI chip (ΔZ) are key factors limiting spatial resolution. In order to improve the spatial resolution, we have developed a micro-SQUID and the vacuum chamber housing both the micro-SQUID and the LSI chip. The Aeff of the micro-SQUID is a thousand of that of a conventional SQUID. The minimum value of ΔZ was successfully reduced to 25 µm by setting both the micro-SQUID and an LSI chip in the same vacuum chamber. The spatial resolution in the second step was shown to be 53 µm. Demonstration of actual complicated defects localization was succeeded, and this result suggests that the two step localization method is useful for LSI failure analysis.