bluuebunny/crossref_metadata_2025_split huggingface dataset:
Propagation characteristics for mobile reception of satellite broadcasting in urban areas
Authors: Ito Yasuhiro 
Published: July 2007

AbstractWhen various broadcasting radio waves in the 12‐GHz band from a geostationary satellite such as a broadcasting satellite are received in an urban area by a mobile receiver, transmission and reception systems such as a temporal diversity system often are designed. In such instances, it is necessary to evaluate quantitatively the mobile receiving characteristics such as the areal visibility on an urban street. When driving on an urban street, one finds that the waves from satellites frequently are disturbed by buildings. The degree of disturbance depends on the direction of the street, the density, height and width of the building.This paper describes first characteristics of measured satellite areal visibility on a road using an airscape photographed at a time when the apparent locations of the satellite and the sun coincide. The histogram of the visibility length is modeled by a log normal distribution. Second, from these distributions and the measurement and analysis of the actual velocity characteristics of automobiles in the Tokyo metropolitan area, the histogram of the visibility duration time is estimated. Third, an estimation method of the satellite areal visibility on a road is proposed in which the statistical data are published by a governmental agency on the building distributions and on the road. The results obtained by these measurement and estimations can provide quantitatively the mobile receiving characteristics of satellite broadcasting at 12 GHz so that they can be effective guidelines in the design of various transmission and reception systems.
Electromagnetic wave excitation in a rectangular tunnel with impedance walls
Authors: Matsunaga Toshiaki , Uchida Kazunori , Noda Takeaki 
Published: July 2007

AbstractThis paper analyzes the problem of excitation of an electromagnetic wave inside a rectangular tunnel by means of the waveguide modes. As the boundary condition, the surface impedance approximation will be used. It is assumed that the separable solution can be adopted. For the excitation by a waveguide, the Wiener‐Hopf solution of the two‐dimensional problem is assumed to be applied. Although the results obtained are approximate, future applications are expected since an analytical expression is provided. For instance, the solution may be applied to the problem of electromagnetic wave propagation in a three‐dimensional tunnel with branches and bends. In the experiment, a microwave simulation is carried out with a model of the tunnel made of concrete. It is found that the computed results and the measured results agree rather well for the electric field intensity distribution inside the tunnel.
Theoretical analyses of a capacity controlled digital microwave radio transmission
Authors: Komaki Shozo 
Published: July 2007

AbstractCapacity‐controlled digital microwave radio systems that can improve the traffic throughput by adapting the transmission capacity according to the level of traffic are described. Calculated throughput values for the 22n‐QAM and Mphase‐PSK modulation technique in the presence of Rayleighan fading are compared with the Shannon limit. The results suggest that throughput improvement by a factor of 1.5 to 3 can be achieved.
Trellis coded modulation for mobile‐satellite communication using space diversity
Authors: Umeda Masatoshi , Murata Masashi , Morinaga Norihiko 
Published: July 2007

AbstractMost of the past studies concerning the decoding performance of trellis coded modulation (TCM) in a fading channel have been based on time diversity using interleaving/deinterleaving. One problem with time diversity is that a large decoding delay is produced due to the interleaving/deinterleaving which depends on the fading interval. This paper considers TCM signals using space diversity which can drastically improve the decoding delay and analyzes the decoding characteristics in Rice fading channels. An analysis is also made of the effect of the Euclidean distance (ED) and the Hamming distance (HD) of the trellis code on the average bit error rate (BER), and it is shown that a code design considering those two distance structures is needed in a channel with severe fading.This paper considers the major application of the proposed method to be digital voice transmission in mobile communication via satellite. Consequently, a simulation is made for the second‐order space diversity decoding performance for the trellis coded 8‐PSK signal. The optimal trellis coding at the transmitter is discussed for BER = 10−4.
A digital signature scheme on a document for MH facsimile transmission
Authors: Tanaka Kiyoshi , Matsui Kineo 
Published: July 2007

AbstractThis paper proposes a digital signature scheme for a facsimile document which embeds a signature directly onto the document. The scheme modifies each run of white or black pixels with a single bit of the signature data. It is designed to be compatible with CCITT G3 facsimile standards and to protect the document from the insertion, modification, replacement, overwriting or deletion of characters. Furthermore, the total amount of data to be transmitted is about the same as that of the original facsimile document. In this paper, an authentication scheme is shown with a prototype model under a one‐key encryption system.
A study on subscriber optical line‐switching networks
Authors: Imai Michitaka , Sankawa Izumi , Furukawa Shin‐Ichi 
Published: July 2007

AbstractIn subscriber optical line networks, it is necessary to take measures to accompany the reliability improvements to efforts concerning the increases in the speed of information communications and the diversity of the services.In this paper, in regards to the structure of the line switching of the loop networks, the optimized settling method of the switch and its structure are investigated. The efficient switching method, in case of a failure, also is shown.Finally, the results of the trial manufacturing of the switch with the required functions are discussed. As the network structure, the one with its feeder lines pulled into many loop lines in one central office is modelled. In such network structures, exclusive protection lines are accommodated, taking into account the circuit failure ratio and the efficiency of line usage, etc.The switching is possible at the branching points of the feeder and the distribution lines between the service and the protection lines. By attaching the switching possibility at the feeding and crossing points to the protection lines, failure of one loop network is shown to be relieved effectively. Finally, the four‐terminal switch possessing the required functions in regards to the present line‐switching networks is proposed and compared against the usual 1 × 2 and 2 × 2 switches. It is shown that it is possible to realize the line‐switching networks with considerably reduced number of switches. Then, from the trial manufacturing results, the possibility of realization of high‐speed and low‐loss switches is indicated.
Performance evaluation of large‐scale data flow‐controlled switching systems
Authors: Yamada Shigeki , Ito Toshio 
Published: July 2007

AbstractThe performance of data flow‐controlled switching systems with processing elements (PEs) on the order of 100 to 1000 is evaluated by software simulation.For the large‐scale simulations, a simplified model is proposed to reduce the required number of computer resources, similar to memories and CPU times.The simulations show that a very large‐scale data flow switching system is feasible by separating mutual exclusion processing PEs from general processing PEs. The performance results are compared with calculations of an approximate model. These results help us to establish the optimum design parameters for the system.
Mobile propagation loss prediction for arbitrary urban environments
Authors: Sakagami Shuji , Kuboi Kiyoshi 
Published: July 2007

AbstractThis paper describes the estimation of the propagation loss in an urban environment important for channel design of land mobile communication. Conventional methods for estimating the propagation loss in an urban environment gives a representative value of the propagation loss in the urban environment or the propagation loss (median value) within a 500 m × 800 m area obtained by introducing an area factor of occupied buildings. Such a method is not suitable for estimation of the propagation loss depending on the situation near the mobile station.In this paper, the relationship of the measured data of the propagation loss in the Tokyo Metropolitan area at 813 and 1433 MHz with the urban environment parameters such as the base station antenna height, distance, frequency, width of the street where the mobile station exists, direction, average building height, building height on the street side is derived by the multiple regression analysis method.A prediction formula for the propagation loss (median value in the section of about 80 m) including these parameters is derived. The parameter dependencies of the propagation loss, such as the antenna height dependence and the average building height dependence, are described. In addition, the distance dependencies of the propagation loss in this prediction formula and conventional method are compared with the measured values. The prediction formula is expressed in terms of the sum of simple functions of the foregoing parameters. Hence, the estimation of the propagation loss can be carried out easily, taking into consideration the urban environments such as the height of the buildings and width of the streets.
An evaluation of test sequence generation methods for communication protocols
Authors: Nakahara Akiko , Aida Hitoshi , Saito Tadao 
Published: July 2007

AbstractIn the conformance test of the communication protocol, it is desired from the viewpoints of strictness and efficiency to generate automatically the test sequence, based on the formal description. Several methods have been proposed for this purpose. All of these methods are based on the two formal descriptions which can be the basis for the test‐sequence generation: one is the description based on the order of the input/output events, and the other is the description based on the finite‐state machine model.This paper attempts to compare the applicability of the two description methods to the conformance test. Also, it evaluates the error‐detection capability which actually generates the test sequences for the following two cases.(1) The test sequence is generated directly from the specification based on the order of events.(2) The test sequence is generated from the finite‐state machine model, which is obtained from the description of (1). In the evaluation, a simulation technique is employed which uses as a testing object a finite‐state machine containing random errors.Finally, this paper notes the handling of the undefined transitions contained in a large number in the actual protocol and considers the class of errors pertinent to the actual protocol, such as the redundant state errors or the replicated state errors.
Degradations of bit‐error ratio due to echo in optical OOK communication systems
Authors: Yoshino Takayuki , Abe Mayumi , Hirano Nobuo 
Published: July 2007

AbstractEchoes, which are transmission waves arriving at a receiver later than the principal wave, arise from multiple reflections at discontinuous points, such as connectors, on a transmission line and cause intensity fluctuations onto a laser light to be received. The intensity fluctuations and its effect on bit‐error ratios in binary on/off‐keying (OOK) optical fiber communication systems are analyzed theoretically here.Analysis features and principal results are as follows: (i) a general theory is developed, including the case of short time delay; and it is shown that the bit‐error ratio degradation decreases when the time delay is shorter than the coherence time of a laser light; (ii) the analysis has no restrictions to amplitude ratio of the echo to the principal wave, so that a critical value of an echo amplitude for floor effect and its corresponding floor values can be evaluated; and (iii) since bit‐error ratios are obtained directly from the probability density function of intensity fluctuations, rigorous results are obtained. This paper considers PIN diodes in detail. Only results for the avalanche photodiode (APD) are presented.
Edgeworth series expansion of apd output current and its application to the evaluation of bit‐error ratio in optical communication systems
Authors: Yoshino Takayuki , Abe Mayumi , Hirano Nobuo 
Published: July 2007

AbstractThe use of a probability density function expanded into Edgeworth series of an APD output current instead of a Gaussian density function aids in the development of a theory of an APD behavior that is both more rigorous and practical. The determination procedure for both the optimum multiplication factor and the optimum symbol decision level is described through application of the theory to bit‐error‐ratio evaluation in optical communication systems.The results reveal that the bit‐error ratios are evaluated about two orders lower when Gaussian approximation is employed. The theory of an APD behavior with the series is used to estimate the bit‐error‐ratio degradations and floor effects on bit‐error‐ratio curves that result from echoes on the transmission lines of the forementioned communication systems. Finally, general results are obtained without any restrictions to echo amplitude or delay time.
Null beam forming by phase control of selected elements in phased‐array antennas
Authors: Chiba Isamu , Mano Seiji 
Published: July 2007

AbstractIn phased‐array antennas, nulls of the radiation pattern can be formed in the direction of undesired wave by controlling only the phase excitation without affecting the main beam. However, the computation time becomes very large when an antenna with a large number of elements is analyzed and it becomes very difficult to counteract the variation of wave boundary instantly.Here, based on the exact calculation of phase value by the method of plane‐wave synthesis, the foremen‐tioned elements are selected which contribute more to the null formation, and the method of controlling only the phase of the selected elements is presented. Using this method, the computation time can be reduced. Moreover, the depth of nulls and the gain of the main beam obtained in this way is the same as that produced by controlling the phase of all the antenna elements.As a result of numerical simulation and experiments of null forming in the phased‐array antenna using a 5‐bit phase shifter, deep nulls with the level of less than ‐40 dB could be formed without decreasing the gain of the main beam.
Design support for the communication service specification by utilizing petri nets
Authors: Hasegawa Haruo 
Published: July 2007

AbstractThis paper describes a support system which designs a complete and error‐free service specification from ambiguous user requirements in a communication system. Each of the user requirements, defined as a combination of terminal operation and a reaction of a switching system to it, is converted into an individual service graph (ISG); and all ISGs are integrated into a total service graph (TSG) which is the final service specification. TSG is verified by three methods: a semantical one, a logical one, and a prototyping one. Then TSG is converted into SDL representation so that it can be used to design communication software.
A limited retransmission CSMA/CD system
Authors: Yamaguchi Takao , Fujiwara Chikato , Okumoto Takaaki 
Published: July 2007

AbstractIn the CSMA/CD LAN system, such as Ethernet, the throughput and the delay characteristics are greatly deteriorated by the increase of the traffic, and several remedies have been proposed.This paper proposes a limited retransmission CSMA/CD system which can achieve a high throughput and easily realizes the retransmission algorithm. Also, the performance of the limited retransmission nonpersis‐tent CSMA/CD system is analyzed and evaluated, among limited retransmission CSMA/CD systems. The validity of the analysis is demonstrated by a simulation. Then the performances are compared among the limited retransmission CSMA/CD system, including the limited retransmission 1‐persistent CSMA/CD system, the traditional nonpersistent and 1‐persistent CSMA/CD systems, as well as an Ether‐type CSMA/CD system.Finally, the limited retransmission 1‐persistent CSMA/CD system is considered as an example, and a modified limited retransmission algorithm is shown, by which the variance of the message transmission delay can be reduced. The extent of the improvement is demonstrated by a simulation.
0.78‐μm digital transmission characteristics using 1.3‐μm optimized single‐mode fiber for a subscriber loop
Authors: Suto Ko‐Ichi , Yoneda Etsugo , Hayakawa Tadahiko , Tuchiya Toshiyuki 
Published: July 2007

AbstractThe transmission characteristics of digital systems comprised of 1.3‐μm zero dispersion, single‐mode fibers (1.3‐μm SMF) and 0.78‐μm band laser diodes (LD) are investigated. The problems encountered in such systems are the degradation of the transmission bandwidth due to the modal noise and the dispersion.This paper describes the transmission‐distance limitations due to the mode dispersion and the range of suitability of short wavelength sources in conjunction with the 1.3‐μm SMFs is clarified. It is shown from the measurement of the long‐term bit‐error rate that the self‐pulsation LDs are useful. It is shown also that the bandwidth‐distance product is limited to 111 MHz km due to the maximum delay difference of 3 ns/km between LP01 and LP11 modes of 1.3‐μm SMFs fabricated by the VAD method. Finally, the selection rules of the optical sources are described taking into account the degradations due to the modal noise.
Topological design of corporate communication networks
Authors: Watanabe Atsushi , Ohmae Yoshitsugu 
Published: July 2007

AbstractRecent construction of corporate communication networks with the use of high‐speed digital links, etc., is becoming popular. Economical and reliable networks must be designed. Few papers have been published on the design of corporate communication networks. Moreover, some need improvement.This paper proposes a new topological design algorithm for efficiently constructing economical and reliable corporate communication networks. This algorithm achieves effective network design by utilizing the correct network information. The triangle network configuration, which provides higher reliability than two‐connected networks with only a small additional cost, is proposed. Moreover, this paper proposes a new idea at a lower cost (cost lower bound) that evaluates the results obtained by various heuristic algorithms. Superiority of the proposed algorithm is verified by means of this cost lower bound.
MS synchronization networks using digital signal processing PLL with different phase error averaging number in each slave level
Authors: Hayashi Minobu , Luan Zaihua , Sasase Iwao , Mori Shinsaku 
Published: July 2007

AbstractWhen the scale of a network is expanded in the master‐slave synchronization system, a problem occurs in that the jitter produced in the upper‐level station propagates and accumulates in the lower‐level station.This paper proposes a master‐slave synchronization network, where the digital signal processing PLL averaging different phase errors is used at each level, with the number of averaging depending on the level. The network in which the number of averaging increases linearly from the upper to the lower level, as well as the network in which the number of averaging increases nonlinearly according to the accumulation of the jitter are considered.It is shown that the jitter characteristic for the whole network is improved for the same acquisition time compared to the network with the uniform number of averaging. With regard to the two networks considered, the optimal increment is derived for the linearly increasing case. It is shown that the improvement is more remarkable in the second network than in the first, and the improvement is more remarkable in either network with the increase of the network scale.
Experimental verification of real‐valued orthogonal PN sequence applied to pulse compression sonar
Authors: Tanada Yoshihiro , Yoshida Hiroshi , Nagasawa Yoji 
Published: July 2007

AbstractIn the pulse compression sonar, the code with a sharp autocorrelation function is used as in spread spectrum communication, and they share many common technologies. In this paper, the real‐valued orthogonal pseudo‐noise (PN) sequence that can be used in both over a broad frequency range including dc is applied to the pulse compression sonar. By adapting digital correlation processing, a high performance close to the theory has been obtained. The codes are generated from a binary orthogonal PN sequence with a length of 127 and a multivalue orthogonal PN sequence with a length of 256 and are sent into an acoustic transmission path at a frequency of about 40 kHz. The correlation operation of the received code and the transmitted code is carried out on a personal computer. The multiple echo is detected at a low noise while the Gaussian noise and the locked sinusoidal wave can be suppressed with a processing gain close to the one predicted by the theory.
Detection of objects by synthetic aperture FM‐CW radar
Authors: Yamaguchi Yoshio , Mitsumoto Masashi , Kawakami Atsushi , Sengoku Masakazu , Abe Takeo 
Published: July 2007

AbstractThe frequency‐modulated continuous‐wave (FM‐CW) radar is suitable for detecting objects placed in the near range compared to the pulse radars. This paper considers the principle of the synthetic aperture technique for the conventional FM‐CW radar and presents the fundamental detection results of objects placed in the free space. A laboratory measurement is carried out to detect a metallic plate and a pipe in an anechoic chamber using an explored radar system operative in the microwave X‐band. This demonstrates the high resolution detection in azimuth direction in the Fresnel region. It is shown that the radar has a potential ability in imaging objects placed in the near range.
Applicability of OSI directory to universal personal telecommunication (UPT)
Authors: Obana Sadao , Horiuchi Hiroki , Kato Toshihiko , Suzuki Kenji 
Published: July 2007

AbstractThe universal personal telecommunication (UPT) is expected as one of the future advanced telecommunication services, which enables telecommunication among subscribers while allowing personal mobility. In UPT, the database (UPT name server) is indispensable, which provides such information as address information and service profile, which are needed by the network in routing, switching control, and service control.This paper aims at the efficient and economical realization of UPT and discusses the application of the existing OSI Directory standard to the UPT name server. First, the functions needed in the UPT name server are systematically categorized and classified. Five mapping rules are proposed, which maps those functions to the OSI Directory functions. Based on those mappings, a prototype for the UPT name server is constructed. The performance and the file volume are examined experimentally, and the applicability of the OSI Directory to the UPT name server is demonstrated.