A new source model for MoM analysis by using sinusoidal reaction matching technique is proposed for linear antenna analysis. This source model assumes a constant feeding gap and uniform electric field distribution inside the gap. The analysis results are compared with the results of the conventional models and measurement. It is found that the new model can incorporate the effect of the length of driving gap and is more accurate and more stable than that from the conventional source models. The proposed source model is simple and easy to use. This source model, together with the full kernel formulation, makes it possible to analyze the linear dipole antennas with no limitation of ratio of segment length to radius.

A term rewriting system which effectively preserves recognizability (EPR-TRS) has good mathematical properties. In this paper, a new subclass of TRSs, layered transducing TRSs (LT-TRSs) is defined and its recognizability preserving property is discussed. The class of LT-TRSs contains some EPR-TRSs, e.g., {f(x)f(g(x))} which do not belong to any of the known decidable subclasses of EPR-TRSs. Bottom-up linear tree transducer, which is a well-known computation model in the tree language theory, is a special case of LT-TRS. We present a sufficient condition for an LT-TRS to be an EPR-TRS. Also reachability and joinability are shown to be decidable for LT-TRSs.

Transmission characteristics of a high permittivity NRD guide were investigated. A preferable operating mode of the high permittivity NRD guide was newly identified and the wide bandwidth and low loss nature of the millimeter-wave region were observed. Moreover, a technique for construction of a millimeter-wave antenna was developed based on the high permittivity NRD guide. The novelty of the present technique lies in the use of a simple radiator, which consists of a tapered dielectric strip of simple structure which has good compatibility with millimeter wave integrated circuits. Since this radiator has a broad radiation pattern, a new type of antenna compatible with millimeter-wave integrated circuits for marine radar use was fabricated by locating the radiator at the focal point of a cylindrical parabolic reflector. Suitable beam patterns with half-power beam widths of 4in the azimuth plane and 38in the elevation plane can be obtained at 35 GHz.

Let each vertex v of a graph G have a positive integer weight ω(v). Then a multicoloring of G is to assign each vertex v a set of ω(v) colors so that any pair of adjacent vertices receive disjoint sets of colors. A partial k-tree is a graph with tree-width bounded by a fixed constant k. This paper presents an algorithm which finds a multicoloring of any given partial k-tree G with the minimum number of colors. The computation time of the algorithm is bounded by a polynomial in the number of vertices and the maximum weight of vertices in G.

In this paper, we consider the problem of multicasting a message in k-ary n-cubes under the store-and-forward model. The objective of the problem is to minimize the size of the resultant multicast tree by keeping the distance to each destination over the tree the same as the distance in the original graph. In the following, we first propose an algorithm that grows a multicast tree in a greedy manner, in the sense that for each intermediate vertex of the tree, the outgoing edges of the vertex are selected in a non-increasing order of the number of destinations that can use the edge in a shortest path to the destination. We then evaluate the goodness of the algorithm in terms of the worst case ratio of the size of the generated tree to the size of an optimal tree. It is proved that for any k 5 and n 6, the performnance ratio of the greedy algorithm is c kn - o(n) for some constant 1/12 c 1/2.

Existing research related to RSVP with mobility support has mainly focused on maintaining reservation state along the routing path, which changes continuously with the movements of mobile host (MH), without much overhead and delay. However, problems such as deepening RSVP's inherent scalability problem and requiring significant changes in the existing network infrastructure have not been adequately addressed. In this paper, we propose a new approach, known as Concatenation and Optimization for Reservation Path (CORP), which addresses these issues. In CORP, each BS pre-establishes pseudo reservations to its neighboring BSs in anticipation of the MH's movement. When the MH moves into another wireless cell, the associated pseudo reservation is activated and concatenated to the existing RSVP session to guarantee continuous QoS support. Because a pseudo reservation is recognized as a normal RSVP session by intermediate routers, little change is required in the current Internet environment to support both movements within a single routing domain and between two different routing domains. CORP also dynamically optimizes the extended reservation path to avoid the infinite path extension problem. Multicast addressing is used to further reduce resource consumption in the optimization process. The experimental results of the CORP implementation demonstrate that it significantly reduces the delay and overhead caused by handoffs compared to the case of establishing a new RSVP session. The improvement increases as the distance between the MH and its correspondent host (CH) grows.

The use of fluid Generalized Processor Sharing (GPS) algorithm for integrated service networks has received much attention since early 1990's because of its desirable properties in terms of delay bound and service fairness. Many Packet Fair Queuing (PFQ) algorithms have been developed to approximate GPS. However, owing to the implementation complexity, it is difficult to support a large number of sessions with diverse service rates while maintaining the GPS properties. The grouping architecture has been proposed to dramatically reduce the implementation complexity. However, the grouping architecture can only support a fixed number of service rates, thus causing the problems of granularity, bandwidth fairness, utilization, and immunity of flows. In this paper, we propose a new implementation approach called dual-rate grouping, which can significantly alleviate the above problems. Compared with the grouping architecture, the proposed approach possesses better performance in terms of approximating per session-based PFQ algorithms without increasing the implementation complexity.

This paper proposes a multipath interference canceller (MPIC) employing multipath interference (MPI) replica generation (MIG) utilizing previously transmitted packet combining (PTPC), which is well-suited to incremental redundancy, in order to achieve a peak throughput of nearly 8 Mbps in a multipath fading environment in high-speed downlink packet access (HSDPA). In our scheme, more accurate MPI replica generation is possible by generating MPI replicas utilizing the soft-decision symbol sequence of the previously transmitted packets in addition to that of the latest transmitted packet. Computer simulation results elucidate that the achievable throughput of the MPIC employing MIG-PTPC is increased by approximately 100 kbps and 200 kbps and the required average received signal energy per symbol-to-background noise power spectrum density ratio (Es/N0) per antenna at the throughput of 0.8 normalized by the maximum throughput is improved by about 0.3 and 0.7 dB compared to that of the MPIC using the soft-decision symbol sequence after Rake combining of the last transmitted packet both in 2- and 3-path Rayleigh fading channels for QPSK and 16QAM data modulations, respectively. Furthermore, we clarify that the maximum peak throughput using the proposed MPIC with MIG-PTPC coupled with incremental redundancy achieves approximately 7 Mbps and 8 Mbps with 16QAM and 64QAM data modulations in a 2-path Rayleigh fading channel, respectively, within a 5-MHz bandwidth.

This paper proposes a flexible tree-based key management framework for a terminal to connect with multiple content distribution systems (called as CDSs in this paper). In an existing tree-based key management scheme, a terminal keeps previously distributed node keys which are used for decrypting contents from a CDS. According to our proposal, the terminal can calculate its node keys of a selected CDS as the need arises, using the "public bulletin board" of the CDS. The public bulletin board is generated by a management center of the individual CDS, depending on a tree structure which it determines in its convenience. After the terminal calculates its node keys, it can get a content of the CDS using the calculated node keys.

A number of results on the estimation of direction of arrival have been obtained based on the assumption that the signal sources are point sources. Recently, it has been shown that signal source localization can be accomplished more adequately with distributed source models in some real surroundings. In this paper, we consider modeling of three-dimensional distributed signal sources, in which a source location is represented by the center angles and degrees of dispersion. We address estimation of the elevation and azimuth angles of distributed sources based on the proposed distributed source modeling in the three-dimensional space using two linear arrays. Some examples are included to more explicitly show the estimation procedures under the model: numerical results obtained by a MUSIC-based method with two uniform linear arrays are discussed.

The capability of a high-temperature superconducting sigma-delta modulator was studied by means of circuit simulation and FFT analysis. Parameters for the circuit simulation were extracted from experimental measurements. The present circuit simulation includes thermal-noise effect. Successive FFT analyses were made to evaluate the dynamic range of the sigma-delta modulator. As a result, the dynamic range was evaluated as 60.1 dB at temperature of 20 K and 56.9 dB at temperature of 77 K.

There is a strong demand to expand captioned broadcasting for TV news programs in Japan. However, keyboard entry of captioned manuscripts for news program cannot keep pace with the speed of speech, because in the case of Japanese it takes time to select the correct characters from among homonyms. In order to implement simultaneous subtitled broadcasting for Japanese news programs, a simultaneous subtitling system by speech recognition has been developed. This system consists of a real-time speech recognition system to handle broadcast news transcription and a recognition-error correction system that manually corrects mistakes in the recognition result with short delay time. NHK started simultaneous subtitled broadcasting for the news program "News 7" on the evening of March 27, 2000.

The purpose of this paper is to derive a novel fractionally spaced Bayesian decision feedback equalizer (FS-BDFE). The oversampling technique changes single input single output (SISO) linear channel to single input multiple output (SIMO) linear channel. The Bayesian decision variable in the FS-BDFE is defined as the product of Bayesian decision variables in the Bayesian decision feedback equalizers (BDFE) corresponding to each channels of the SIMO. It can be shown that the FS-BDFE has less decision error probability than the conventional BDFE. The effectiveness of the proposed equalizer is also demonstrated by the computer simulation.

This paper presents a fuzzy control-based intelligent medium access controller (FiMAC), which optimizes random access control between heterogeneous traffic aiming at more efficient voice/data integrated services in dynamic reservation TDMA-based broadband radio access networks. In order to achieve the design objective, viz. a differentiated quality-of-service (QoS) guarantee for individual service plus maximal system resource utilization, the FiMAC intelligently and independently controls the random access parameters such as the lengths of random access regions dedicated to respective service traffic and the corresponding permission probabilities, frame-by-frame basis. In addition, we have adopted a mobile-assisted random access mechanism where the voice terminal readjusts a global permission probability from the FiMAC, to handle the 'fair access' issue resulting from distributed queueing problems inherent in the access network. Our extensive simulation results indicate that the FiMAC is well coordinated with a mobile-assisted mechanism such that significant improvements are achieved in terms of voice capacity, delay, and fairness over most of the existing MAC schemes for the integrated services.

The adaptive base station antenna is an attractive candidate for establishing high-speed and highly-reliable wireless communication systems. From a commercial viewpoint, since the cost and complexity of adaptive antennas depend on the number of elements, optimizing the antenna configuration while considering the propagation environment is necessary to reduce the number of elements. This paper first presents the Angle of Arrival (AOA) characteristics of delayed waves in a street microcell environment, typically used in urban microcell systems. Then the antenna configuration and antenna spacing suitable for the street microcell are investigated utilizing bit error rate (BER) performance simulations using practical delay profiles and AOAs. The effectiveness of bidirectional elements with respect to the BER performance is also investigated. As the results, we found that broadside array with the spacing of 2.5 wavelengths is suitable for adaptive base station antennas for high data-rate wireless systems placed in a street microcell environment. We also found that bidirectional elements alleviate the BER degradation due to the grating lobe of the antenna with wide element spacing without increasing the antenna size.

This paper presents a model called PECM (process environment coordination model) to coordinate heterogeneous PSEEs. A PSEE coordinated by PECM is associated with a standard-interfaced PECM coordinator, which provides primitive coordination functions. PECM uses shared product status to coordinate PSEEs. It is expected to offer several features. First, multiple PSEEs can be used in the same project. Second, PECM manages products and product relationships across PSEEs. Third, PECM coordinator is standard- interfaced, which is easy to use.

A wireless communications system with a transmission speed of 18 Mbit/s is presented using the 2.4 GHz ISM band. This system employs the Carrier Frequency Offset-Spread Spectrum (CFO-SS) scheme and the Dual-Polarization Staggered Transmission (DPST) scheme. The 18 Mbit/s CFO-SS system (named CFO-SS18) was developed and its performance evaluated in fields. In this paper, the detailed operating principle of CFO-SS and DPST schemes, together with the specifications and structures of CFO-SS18, are presented. Results of indoor and field tests obtained by using CFO-SS18 are also presented.

As a remarkable development of VLSI technology, a gate switching delay is reduced and a signal delay of a net comes to have a considerable effect on the clock period. Therefore, it is required to minimize signal delays in digital VLSIs. There are a number of ways to evaluate a signal delay of a net, such as cost, radius, and Elmore's delay. Delays of those models can be computed in linear time. Elmore's delay model takes both capacitance and resistance into account and it is often regarded as a reasonable model. So, it is important to investigate the properties of this model. In this paper, we investigate the properties of the model and construct a heuristic algorithm based on these properties for computing a wiring of a net to minimize the interconnection delay. We show the effectiveness of our proposed algorithm by comparing ERT algorithm which is proposed in [2] for minimizing the maximum Elmore's delay of a sink. Our proposed algorithm decreases the average of the maximum Elmore's delay by 10-20% for ERT algorithm. We also compare our algorithm with an O(n4) algorithm proposed in [15] and confirm the effectiveness of our algorithm though its time complexity is O(n3).

We introduce a clock schedule algorithm to obtain a clock schedule that achieves a shorter clock period and that can be realized by a light clock tree. A shorter clock period can be achieved by controlling the clock input timing of each register, but the required wire length and power consumption of a clock tree tends to be large if clock input timings are determined without considering the locations of registers. To overcome the drawback, our algorithm constructs a cluster that consists of registers with the same clock input timing located in a close area. The registers in each cluster are driven by a buffer and a shorter wire length can be achieved. In our algorithm, first registers are partitioned into clusters by their locations, and clusters are modified to improve the clock period while maintaining the radius of each cluster small. In our experiments, the clock period achieved in average is about 13% shorter than that achieved by a zero-skew clock tree, and about 4% longer than the theoretical minimum. The wire length and power consumption of a clock tree according to an obtained clock schedule is comparable to these of a zero skew tree.

A problem of obtaining an optimal file transfer of a file transmission net N is to consider how to transmit, with the minimum total cost, copies of a certain file of information from some vertices, called sources, to other vertices of N by the respective vertices' copy demand numbers. This problem is NP-hard for a general file transmission net N. Some classes of N, on each of which a polynomial time algorithm for obtaining an optimal file transfer can be designed, are known. In the characterization, we assumed that file given originally to the source remains at the source without being transmitted. In this paper, we relax the assumption to the one that a sufficient number of copies of the file are given to the source and those copies can be transmitted from the source to other vertices on N. Under this new assumption, we characterize a class of file transmission nets, on each of which a polynomial time algorithm for obtaining an optimal file transfer can be designed. A minimum spanning tree with degree constraints plays a key role in the algorithm.