bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance evaluation of burst‐based bandwidth‐reservation method in ATM networks
Authors: Wakamiya Naoki , Baba Ken‐Ichi , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractThis paper considers the asynchronous transfer mode (ATM) network and evaluates the burst‐based allocation of the virtual channel (VC) bandwidth. In the traditional call‐based bandwidth allocation by statistical multiplexing based on the bursty property of the traffic, the cell loss is inevitable due to the short‐term traffic congestion.This paper also considers the data terminal where the transmission rate can be adjusted through the negotiation with the network and evaluates the burst‐based bandwidth allocation mechanism. It is assumed in the proposed method that the virtual path (VP) is already divided into a number of channels and the channel is allocated for each burst. The data transfer by such a bandwidth‐reservation method is evaluated quantitatively by an analytical approach, and an adequate division into VP channels is indicated.
Minimization of the number of links in three‐level hierarchical telecommunication networks
Authors: Mase Kenichi 
Published: July 2007

AbstractMinimizing the number of links (trunk groups) is important in reducing not only the equipment cost but also the operation and maintenance costs in a digital toll‐switching network. However, by minimizing the number of links in a digital toll‐switching network, obtaining an optimal area configuration is a problem. This is because the fixed idea that the area configuration of such a network is invariable is disregarded.In this paper, the multiunits of a three‐level toll‐switching network are considered and factors determining the number of the links are modeled. Then it is shown that the number of links is minimized when the areas of upper‐ and lower‐level toll‐switching centers are constructed equally. In addition, conditions for an optimal area configuration that minimizes the number of links are shown by numerical examples for two‐level and three‐level networks of conditions that minimize the increase in the number of units of toll switches and more than two switch units of a toll‐switching center for ensuring reliability. As a result, it is shown that a three‐level network is advantageous compared with a two‐level network since the capacity of a toll switch is small and the traffic current tends to concentrate at a near distance.
Method of estimating the maximum radiated interference field of electronic equipment by using randomly assigned phase terms
Authors: Murakawa Kazuo , Kuwabara Nobuo 
Published: July 2007

AbstractUsing the electric field strength measurement value vicinal to electronic equipment set up in a factory, investigation was made by the experimental method stipulated by VCCI, that is, by both theory and experiment, estimating the maximum value of the electric field strength measured for the set‐up of electronic equipment at the test site by the 10‐m test method.In the estimation method proposed, the electric field strength in the vicinity of electronic equipment is measured in cylindrical form, the phase of the measurement point is assigned by uniform random number and, employing the integral expression of electric field using these values, the maximum value of the electric field strength of the estimation surface is estimated.In the investigation, even in the case of assigning phase by random numbers, it was found theoretically possible to estimate within 6‐dB accuracy the maximum value of the electric field strength of the estimation surface. Moreover, as a result of investigating the accuracy of the estimation method using a spherical dipole antenna as a radiation interference source, it was confirmed experimentally that the deviation between the estimated value and measurement value is roughly below 4 dB over a frequency of 100 MHz to 1 GHz.
Use of neural networks for the optimum frequency assignment problem
Authors: Kurokawa Takakazu , Kozuka Shigeki 
Published: July 2007

AbstractWhen two satellites in close proximity to each other use the same frequency band, mutual signal interference is unavoidable. Especially, it is known in the FDMA communication system that the interference to each carrier and the total interference depends greatly on the carrier frequency assignment. At the present stage, where a large number of satellites have entered into operations, the assignment of the frequencies is becoming ever more important.This paper aims at a high‐speed determination of the signal carrier assignment so that the signal interference is minimized and proposes a method of parallel solution using a Hopfield‐type neural network. In the proposed solution method, the given frequency band is segmented into n frequency bands and the assignment is derived by rearranging the segments using the two‐dimensional neural network array.The following properties were revealed as a result of simulation. The optimal solution or a solution close to the optimal can be determined from a tremendous combination of possible solutions, while suppressing the explosive increase of the computational complexity with the increase of the problem size. The power to derive the solution depends on the carrier configuration.
Standardization aspects of B‐ISDN–‐technical issues in high‐speed data communications services deployment
Authors: Imai Kou Miyake Kazuo 
Published: July 2007

AbstractThis paper discusses issues in the research of B‐ISDN standardization being conducted by the CCITT and other institutions, the results of this research to date, and possible future studies. More specifically, it discusses the technology of deploying high‐speed data communications services for initial services.
Heterodyne optical detection/spatial tracking system using spatial field pattern matching between signal and local lights
Authors: Tsukamoto Katsutoshi , Morinaga Norihiko 
Published: July 2007

AbstractThe spatial tracking system controlling the directivity of the optical antenna determines the quality of communication in the ultradistance intersatellite optical communication system. The spatial tracking system using optical heterodyne detection has a high receiver sensitivity, being less susceptible to background light. This is the dominating factor for noise in cosmic space. In recent years, intensive studies have been made on this system hoping for the tracking performance with a higher accuracy than that obtained by the direct detection system.This paper presents a principle of angular error detection which is different from the conventional system and proposes a new optical heterodyne/spatial tracking system based on that principle. The principle on which the proposed system is based is that the incoming angle of the signal light is tracked by utilizing the variation of the spatial matching to the local light due to the variation of the incoming angle of the signal light. Its feature is that the angle error can be detected using a single ordinary optical detector, not the quadrant optical detector.A theoretical analysis of the noise equivalent angle (NEA) is presented. The optimal local light diffraction pattern is shown for the rectangular antenna aperture. The performance of the system is analyzed from the viewpoint of NEA, and the result is compared to the performance of the optical heterodyne detection/spatial tracking system using the quadrant optical detector.
A new design for program‐controlled voice switching circuits using a microprocessor
Authors: Oikawa Hiroshi , Makino Shoji , Nishino Masakazu , Yamamori Kazuhiko 
Published: July 2007

AbstractThe voice switching circuit (VS) is applied widely to various problems, including echo suppression and howling suppression in the communication equipment, realizing the magnified voice communication using microphones and loudspeakers. It is also applied frequently in recent years in combination with the echo canceller, in a form to complement the performance of the echo canceller.Kato et al. [3] discussed in detail the operational performance and the design method when VS is realized by the analog circuit, and proposed the automatic loss switching VS (ALS), where the switching loss is reduced by automatically adapting to the change of the acoustic and side‐tone characteristics. In their method, however, ALS is constructed using only the analog circuit. This makes the design complicated and makes it difficult to reduce the switching loss compared to the present design. With this in mind, the goal here is to realize the ALS function by program control, using the microprocessor (μP). the following two program‐controlled VS with excellent voice communication functions are proposed.
Virtual path trace function and its mechanism for ATM transport networks
Authors: Matsunaga Haruhiko , Ueda Hiromi 
Published: July 2007

AbstractTo make the operation, administration, and maintenance (OAM) functions of virtual path (VP) in the ATM transport network efficient, the authors present a trace method which collects VP route configuration information automatically. This method enables rapid search of VP routes which are managed dynamically. Therefore, it becomes easy to operate and manage the accurate network configuration in ops.In this paper, the requirements for the VP trace method are clarified and mechanisms for the VP trace method realization are presented. Then, the VP trace OAM cell format, the VP trace processing algorithms in each ATM network system, and the implementation of the required functions are discussed. Finally, the VP performance is evaluated.
Global motion compensation in video coding
Authors: Kamikura Kazuto , Watanabe Hiroshi 
Published: July 2007

AbstractAs a motion compensation method for video coding, a global motion estimation method is proposed that estimates and compensates general image motion caused by camera pan and zoom. By utilizing block displacement vectors derived from the widely utilized block‐matching method, global motion parameters are computed with a noniterative process requiring few multiply‐add operations. Parameters associated with pairs of blocks symmetrically located with respect to the center of the image are calculated, and the histogram of these parameters is then used to efficiently compute accurate motion values that depend on nothing but camera pan and zoom. A corresponding block‐by‐block ON/OFF control method is also proposed for the global motion compensation scheme. By utilizing these methods, a relatively simple and efficient coding technique with global motion estimation is realized.
Protocols to accommodate asynchronous transfer mode cells in satellite TDMA links
Authors: Ohta Atsushi , Okada Kazuyasu 
Published: July 2007

AbstractTo deyelop the broadband integrated services digital network (B‐ISDN) service on a national scale and to handle various media in a unified way economically from ‐ an early stage, it will be effective to construct a system combining the satellite link into the terrestrial communication network. the TDMA system is adequate as the transmission system in the satellite link in such a system which can contain efficiently users distributed over a country.When the satellite TDMA link, which is a synchronous system, and the terrestrial network, based on the asynchronous transfer mode (ATM), are to be connected, the deterioration of the ATM transmission quality such as the cell delay variation, is a serious problem. Then there must be a compensation method for the delay variation which can cope with the asynchronous transfer. In such a transformation between ATM and TDMA, it is required that the maximum delay variation should be kept below the specified value, the burstiness of the transferred cell sequence should not be increased, and the satellite link with limited network resources should efficiently be utilized.This paper assumes that the time‐stamp method, which is considered in the ground network, is applied to the satellite link as a method for the delay variation 38 compensation and summarizes the problems in the application. Then the cell‐numbering method is proposed and the performance is evaluated to solve the problems.
Differential detection for 16 amplitude/phase shift keying (16 dapsk) using viterbi algorithm
Authors: Nemoto Koji , Sasase Iwao 
Published: July 2007

AbstractRecently, differentially encoded 16 amplitude/phase shift keying (16 DAPSK) has been investigated intensively for mobile radio applications. Since the bit error rate (BER) performance of differential detection (DD) is inferior to that of coherent detection (CD), multisymbol DD of 16 DAPSK has been proposed. However, as the observation interval of multisymbol DD is increased to improve the BER performance, computational complexity increases.In this paper, the differential detection scheme of 16 DAPSK based on the maximum likelihood sequence estimation (MLSE) using Viterbi algorithm is proposed and the BER performance of the proposed scheme is investigated by computer simulation. It is shown that the BER performance of Viterbi‐decoding DD outperforms that of three‐symbol DD without increasing the computational complexity.
An autonomous provisioning algorithm of remote operation in asynchronous transfer mode networks
Authors: Tsuboi Toshinori , Kikuchi Katsuaki 
Published: July 2007

AbstractTo achieve efficient and highly reliable network operation requires a mechanism to monitor and control the states of remote terminals (nodes) automatically by the central operation system (OpS). This paper is an attempt to obtain such a mechanism. Operation and maintenance (OAM) cell is defined that contains the connection information for remote monitoring and the control path to be set. By successively transferring OAM cells according to the connection information, remote monitoring and control virtual paths (VPs) can be obtained autonomously.Based on the proposed idea, this paper discusses the structure of the OAM cell, the functions to be provided in the cross‐connect system, and transmission algorithms for the OAM cell. The proposed system well utilizes the unique feature of the ATM cell. The cell routing information (VPI) is transferred within itself.
Development of experimental automatic dependent surveillance system and inflight performances
Authors: Ishide Akira , Fujita Mitsuhiro , Niimi Kenji , Matsuzaki Fumitaka , Yukawa Kiyoshi 
Published: July 2007

AbstractThe automatic dependent surveillance (ADS) system has been developed and tested through flight trials using INMARSAT satellites. ADS is a new surveillance system that uses a satellite datalink for aircraft in oceanic areas. Test results showed that the ADS transmission protocol is reliable and message losses are very few, the transmission delay for the R channel is about 3.4 s and that for the T channel is 15.6 s under fair link conditions. The latter should be reduced for additional improvement in surveillance capability in the future. It may increase due to degradation of link condition by aircraft attitude change.
Satellite channel assignment method with control of call‐loss probability for carriers with different transmission bandwidths under frequency‐division multiple access
Authors: Hayashi Masato , Takahata Fumio 
Published: July 2007

AbstractIn the satellite communication system with frequency‐division multiple access (FDMA), the efficient use of the frequency band is very important. This paper discusses the channel assignment method which can realize a high channel utilization for three kinds of information with different bandwidths while efficiently controlling the call loss probability.As conventional methods, the orderly assignment method, which is known to realize a high channel utilization, as well as the separate assignment for each kind of call, where the odd effect is not produced, are considered. For the purpose of this study, the floating boundary assignment (FA) is considered, which is based on the orderly assignment and a new channel search algorithm so that the call loss probability can be controlled. The proposed method is compared to the conventional methods.First, it is shown by the performance evaluation by simulation that the FA method can realize a high channel utilization and the call loss probability control. Using the satellite communication system based on the demand‐assignment scheme, the performance of the FA method is partially examined by experiment. By assuming a precise requirement for the call loss probability, the call loss probability control performance as well as the channel utilization are examined. The proposed FA method is shown to be useful through the comparison.
A delay lock loop using delay path cancellation for mobile communications
Authors: Takeuchi Makoto , Nakagawa Masao 
Published: July 2007

AbstractUnder multipath fading channels, the conventional delay lock loop (DLL) performance is degraded because of delay jitter caused by multipath signals. This error causes a large performance degradation of signal‐to‐noise ratio (SNR). It is necessary to reject the multipath error in order to improve the CDMA mobile communications performance.This paper introduces a new tracking system which cancels the effect of the delayed paths. The proposed system consists of multi‐DLLs, an adaptive equalizer and a replica generator. This system generates a replica of the received signals by employing estimated values of the delay errors and the amplitude levels and removes the undesired signals from the received signal. The performance of this system is evaluated by computer simulations, showing a remarkable improvement of the delay jitter and a better performance of 3 dB at BER of 10−2.
Performance analysis of input and output queueing packet switch with multiple priority classes
Authors: Takemori Keisuke , Shiokawa Shigeki , Sasase Iwao 
Published: July 2007

AbstractThis paper proposes an N X N input‐output buffered switch model which switches several kinds of packets emphasizing the real‐time property as well as packets emphasizing the secure transmission. The model corresponds to the Poisson and Bernoulli traffic switching system. Such performances as the average system queueing delay and the loss probability for the packet emphasizing the real‐time transmission are analyzed. Nonpreemptive priority discipline is applied on the input side where the circuit configuration is relatively simple. On the output side, the first‐come/first‐served (FCFS) process is applied without considering the priority service.In the proposed model, the output buffer size is assumed as finite and the input buffer size is assumed as infinite. For the two kinds of switching systems which serve the Poisson arrival packets and the Bernoulli arrival packets, respectively, the mean system queueing delay for the priority class is analyzed. For the case where the input buffer size is limited for the packet with a high priority emphasizing the real‐time transmission, the relation between the loss probability for the packet with a high priority and the sizes of the input and output buffers is investigated by a computer simulation for the case of two classes. The adequate input buffer size for the packet with a high priority is determined.
Circular patch antennas miniaturized by shorting posts
Authors: Kuga Nobuhiro , Arai Hiroyuki 
Published: July 2007

AbstractAs a small antenna for mobile communication, a circular patch antenna miniaturized with a shorting post is proposed. These shorting posts are placed near the feed post. The circular patch antenna miniaturized by offset feed is excited by a hybrid of the coaxial TM01 mode and the TM11 mode. Hence, the antenna has directivities in several polarization planes so that a low gain pattern not realizable with an antenna with a monopole mode is attained.The theoretical analysis of the antenna is carried out by a cavity model in which an impedance boundary is assumed at the edge of the element. Since the conventional procedure cannot be applied to the coaxial TM01 mode that is the fundamental mode of the antenna, an approximate formulation based on the equivalent circuit containing the feed post and the shorting post as the current sources is proposed. It is confirmed that the numerical results of the input impedance and the experimental results agree well. From the numerical analysis, the modal amplitude characteristics of the magnetic current contributing the radiation and the resonant frequency characteristics of the antenna are discussed from the relationship to the feed method.
Radiation efficiency measurement of a small antenna using the wheeler method
Authors: Muramoto Mitsuru , Ishii Nozomu , Itoh Kiyohiko 
Published: July 2007

AbstractThe antennas for mobile communication handsets have become smaller in shape, which has degraded their electrical performance significantly. To obtain a small but high‐performance handset, it is important to increase the antenna efficiency. The important parameter for such a purpose is the radiation efficiency which can be measured easily by the Wheeler method. This method is carried out based on the assumption that the input power is equal to the power loss if the antenna is covered with a cap of a size on the order of a radian sphere. However, unless this assumption holds, the computed Wheeler efficiency does not give accurate radiation efficiency.When the radiation efficiency is actually measured by the Wheeler method, the measured values often have a dip from the theoretical value. In this paper, the cap is approximated by wire grids and the Wheeler method is simulated on a computer. It is confirmed that the dip is not caused by the measurement method. It is shown that the cause derives from the invalidness of the presumption of the Wheeler method that the internal reactive electromagnetic field does not change when a cap is placed. It is shown also that the Wheeler method can be used sufficiently even if the size of the cap is larger than the radian sphere. The limit of application is studied.
Performance of limited‐state sequence estimation under land mobile frequency‐selective fading channels
Authors: Kamio Yukiyoshi 
Published: July 2007

AbstractThe frequency‐selective fading is one of the problems in the high‐speed transmission in land mobile communications. A solution is to use the Viterbi equalizer. When this method is applied to the highly efficient modulation system such as QPSK, however, the computational complexity increases rapidly with the increase of the delay time of the delayed wave to be compensated. This makes the instrumentation impractical.This paper proposes a method in which the computational complexity is reduced drastically by the limited‐state sequence estimation. In the proposed method, limited‐state sequence estimation (Viterbi algorithm) is applied where two waves with the largest powers are selected based on the estimated impulse response. Based on the tentative decision obtained beforehand by a simple method, the effects of other waves are eliminated. The number of states is estimated considering only the selected two waves.The performance of the proposed method is examined by a computer simulation. It is shown as a result that the range of compensation can be enlarged and the computational complexity can be reduced, compared to the conventional simplified method. In other words, the effectiveness of the proposed method is demonstrated.