In this paper, we propose a new coded orthogonal frequency division multiplex (COFDM)-based ubiquitous antenna system, which is composed of multiple radio base stations (RBSs) deployed over the service area and Radio-on-Fiber (RoF) link that connects RBSs to the central control station (CCS). The proposed system is capable of receiving multiple mobile terminals simultaneously operating at the same frequency by making effective use of joint detection. However, the propagation delay due to the RoF link could be a major problem for realizing the ubiquitous antenna system. In order to overcome this delay problem, we assume that the guard interval of COFDM is longer than the delay difference. Furthermore, in order to improve BER performance in a multipath Rayleigh fading channel, we also propose the MSE normalization scheme followed by the use of an MMSE-based joint detector. Computer simulation results show that the proposed system can improve the frequency utilization efficiency of the broadband wireless access system.

A novel self-alignment process using the surface tension of the liquid resin for assembly of electronic or optoelectronic devices in 3-D space has been proposed. The vertical alignment can be controlled by using of metal sphere, reducing the necessary precise process control such as solder volumes and external forces, and allowing large tolerances in liquid volume and misalignment. Lateral alignment could be also achieved by making the liquid resin constrained on the 3-dimensional pads on chip and substrate. This study focused on the principle of self-alignment and final alignment accuracy. In addition, the possibility of self-alignment process was verified by analytic numerical method and scaled-up experiment. An average alignment accuracy of less than 0.25 µm has been obtained. It is thought that this process is effective for assembly simply at low process temperature, low cost and without flux in future assembly techniques.

This paper proposes a maneuvering target tracking algorithm using multiple model filters. This filtering algorithm is discussed in terms of tracking performance, tracking success rate and tracking accuracies for short sampling interval as compared with other conventional methodology. Through several simulations, validity of this algorithm has been confirmed.

In recent years, several inverse solutions of magnetoencephalography (MEG) have been proposed. Among them, the multiple signal classification (MUSIC) method utilizes spatio-temporal information obtained from magnetic fields. The conventional MUSIC method is, however, sensitive to Gaussian noise and a sufficiently large signal-to-noise ratio (SNR) is required to estimate the number of sources and to specify the precise locations of electrical neural activities. In this paper, a new algorithm for solving the inverse problem using the fourth order MUSIC (FO-MUSIC) method is proposed. We apply it to the MEG source estimation problem. Numerical simulations demonstrate that the proposed FO-MUSIC algorithm is more robust against Gaussian noise than the conventional MUSIC algorithm.

We have developed a novel self-alignment process using the surface tension of the liquid resin for assembly of electronic or optoelectronic devices. Though the liquid resins have a characteristics as low as one tenth of the surface tension of solder in general, restoring forces for self-alignment capability can be produced by making it constrained on the 3-dimensional pads on chip and substrate. In this paper, its principle and characteristics are described and the relationship between process parameters and joint geometry were examined. And the possibility of self-alignment process was verified by analytic numerical method and scaled-up experiment. A self-alignment accuracy was examined experimentally and show that it became less than 0.4 µm. It can provide a useful information on various parameters involved in joint geometry and optimal design guideline to generate the proper profiles.

In this paper, we give an algorithm for the node-to-set disjoint paths problem in rotator graphs with its evaluation results. The algorithm is based on recursion and it is divided into cases according to the distribution of destination nodes in classes into which all the nodes in a rotator graph are categorized. The sum of the length of paths obtained and the time complexity of the algorithm are estimated and verified by computer simulation.

This paper presents a new multi-target data association method for automotive radar which we call the order statistics joint probabilistic data association (OSJPDA). The method is formulated using the association probabilities of the joint probabilistic data association (JPDA) filter and an optimal target-to-measurement data association is accomplished using the decision logic algorithm. Simulation results for heavily cluttered conditions show that the tracking performance of the OSJPDA filter is better than that of the JPDA filter in terms of tracking accuracy by about 18%.

This paper presents an O(n2)-time algorithm for constructing two edge-disjoint paths connecting two given pairs of vertices in a given tournament graph. It improves the time complexity of a previously known O(n4)-time algorithm.

We study the joint optimization problem of a transmitter with multiple transmit antennas and a receiver with multiple receive antennas in a narrow-band communication system. We discuss the problem of designing a pre-filter at the transmitter, a post-filter at the receiver, and a bit allocation pattern to multiple symbols in the sense of minimizing the average bit error rate. With the optimized filters and the bit allocation, we could realize high efficiency and high data rate in band-limited channels.

The blind separation of sources is a recent and important problem in signal processing. Since 1984, it has been studied by many authors whilst many algorithms have been proposed. In this paper, the description of the problem, its assumptions, its currently applications and some algorithms and ideas are discussed.

In this paper we present a distributed routing protocol for finding two node-disjoint paths between each pair of nodes in a computer network. In the proposed protocol, each node in the network has the same procedure, which is driven by local information with respect to the network topology, such as adjacent nodes on a spanning tree in the network. Thus, the execution of the protocol can continue after changes of the network topology and load. Then, a spanning tree-based kernel construction is introduced to synchronize procedures under the distributed control of the protocol. Additionally, the routing scheme based on the protocol possesses the enhanced capabilities of alternate routes and load splitting, which cope with failures and load variations in the network. Thus, even if topology changes damage the obtained disjoint paths, the paths themselves can be updated efficiently.

The Joint CDMA/PRMA (JCP) protocol, proposed by Brand and Aghvami, is modified to increase the capacity for mobile communication systems. To reduce multiuser interference, the modified JCP uses an access channel additionally to the traffic channels, on which each mobile terminal reserves a unique slot and code. Furthermore, the modified JCP employs receiver-based code scheme. In the case of voice-only traffic, the throughput increases by up to 15% compared to that of the conventional JCP, when Ploss is 0.01. Also, for the mixed traffic case, the throughput increases about 20%.

In highly reliable communication network design, disjoint paths between pairs of nodes are often needed in the design phase. The problem of finding k paths which are as diverse as possible and have the lowest total cost is called a k-best paths problem. We propose an algorithm for finding the k-best paths connecting a pair of nodes in a graph G. Graph extension is used to transfer the k-best paths problem to a problem which deploits well-known maximum flow (MaxFlow) and minimum cost network flow (MCNF) algorithms. We prove the k-best paths solution of our algorithm to be an optimal one and the time complexity is the same as MCNF algorithm. Our computational experiences show that the proposed algorithm can solve k-best paths problem for a large network within reasonable computation time.

This paper introduces an adaptive distributed routing algorithm for the faulty star graph. The algorithm is based on that the n-star graph has uniform node degree n-1 and is n-1-connected. By giving two routing rules based on the properties of nodes, an optimal routing function for the fault-free star graph is presented. For a given destination in the n-star graph, n-1 node-disjoint and edge-disjoint subgraphs, which are derived from n-1 adjacent edges of the destination, can be constructed by this routing function and the concept of Breadth First Search. When faults are encountered, according to that there are n-1 node-disjoint paths between two arbitrary nodes, the algorithm can route messages to the destination by finding a fault-free subgraphs based on the local failure information (the status of all its incident edges). As long as the number f of faults (node faults and/or edge faults) is less than the degree n-1 of the n-star graph, the algorithm can adaptively find a path of length at most d+4f to route messages successfully from a source to a destination, where d is the distance between source and destination.

VP Network Designer, a software tool that automates the tasks involved in the transaction of service orders in VP leased line services, is introduced here in this paper. The tool is composed of two functions: VP Design Explorer which, given a request for VP establishment, determines a disjoint backup and target VP routes to support fault tolerance under VP-APS scheme; Network Resource Administrator which provides data administering functions, useful in maintaining a clear insight into the state of the network. The paper focuses on the implementation of VP Design Explorer. A scheme, proposed as disjoint VP routes search, is used to evaluate a pair of VP routes that guarantee duct level independence. The scheme is based on an integer programming modeling approach, and is proved to be effective for evaluating disjoint paths in a hierarchical network. VP Design Explorer is equipped with an additional feature where, under conditions of resource shortage, it presents a set of additional resources that are necessary to satisfy VP demand, together with the VP routes that become possible by the additions. Formulation of the problem is attained through an extension of the disjoint VP routes search scheme. A prototype of VP Network Designer is presented and its performance tested using computer simulations. The tool is found to achieve a computational time performance in the order of seconds and minutes, for evaluating disjoint VP routes search problems under real life ATM network conditions.

A processor allocation scheme for mesh computers greatly affects their system utilization. The performance of an allocation scheme is largely dependent on its ability to detect available submeshes. We propose a new type of submesh, called a link-disjoint submesh, for processor allocation in mesh computers. This type of submesh increases the submesh recognition capability of an allocation scheme. A link-disjoint submesh is not a contiguous submesh as in the previous scheme, but this submesh still has no common communication link with any other submesh. When wormhole routing or circuit switching is used, the communication delay caused by non-contiguous processor allocation is minor. Through simulation, the performance of our scheme is measured and compared to the previous schemes in terms of such parameters as finish time and system utilization. It is shown through simulation that the link-disjoint submesh increases the performance of an allocation scheme.

In this paper, a new trial for the signal processing is proposed along the same line as a previous study on the extended regression analysis based on the Bayes' theorem. This method enables us to estimate a response probability property of complicated systems in an actual case when observation values of the output response are roughly observed due to the quantization mechanism of measuring equipment. More concretely, the main purpose of this research is to find the statistics of the joint probability density function before a level quantization operation which reflects every proper correlation informations between the system input and the output fluctuations. Then, the output probability distribution for another kind of input is predicted by using the estimated regression relationship. Finally, the effectiveness of the proposed method is experimentally confirmed by applying it to the actually observed input-output data of the acoustic system.

Butt-joint waveguide couplings are fabricated for use in InP-based photonic integration, and characterized by scanning electron microscopy and optical transmission measurements. Several parameters have been optimized in the characterization study: size and shape of the mask protecting the first waveguide layer during butt-joint regrowth, and the crystallographic direction of the butt-joint interface. The studies show that high-quality butt-joints having negligible optical loss can be made with good fabrication tolerance. Using the optimized butt-joint, DBR-type, gain-clamped SOAs have been fabricated which are free of internal excess reflections. A constant optical gain of 21 dB is obtained up to a signal output power of 25 mW. The devices show CATV grade linearity in a 77 channel CATV linearity test at a distortion level of -55 dB below carrier.

In this paper, we consider the following node-to-set disjoint paths problem: given a node s and a set T = {t1,...,tk} of k nodes in a k-connected graph G, find k node-disjoint paths s ti, 1 i k. We give an O(n2) time algorithm for the node-to-set disjoint paths problem in n-dimensional star graphs Gn which are (n - 1)-connected. The algorithm finds the n - 1 node-disjoint paths of length at most d(Gn) + 1 for n 4,6 and at most d(Gn) + 2 for n = 4,6, where d(Gn) = 3(n-1)/2 is the diameter of Gn. d(Gn) + 1 and d(Gn) + 2 are also the lower bounds on the length of the paths for the above problem in Gn for n 4,6 and n = 4,6, respectively.

A joint estimator for carrier phase, symbol timing, and data sequence is proposed. This fully digital scheme is systematically derived from the maximum likelihood estimation (MLE) theory. The simulation and the analytical results demonstrate that the scheme is asymptotical to the optimum in AWGN channel.