bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advanced signaling protocol for broadband ISDN services
Authors: Kuribayashi Shin‐Ichi , Shiraishi Satoshi 
Published: July 2007

AbstractA signaling functional model (separated model) that assumes the functional separation of call control (CC) and bearer control (BC) must be considered for B‐ISDN because B‐ISDN deals with various levels of service quality, various speeds, and various connection configurations. This paper provides the basic structure of the forementioned separated model and the functions of the CC and BC based on actual B‐ISDN service specifications. Also, system design guidelines are proposed for connection‐type bandwidth selection and interworking between broadband ISDN and narrowband ISDN, which are key issues in the study of B‐ISDN signaling protocol.
Approximate performance evaluation method for TST‐type switching networks employing multislot connections
Authors: Hayashi Zenji 
Published: July 2007

AbstractThis paper describes the method for approximate evaluation of the performance of TST‐type switching networks employing multislot connections. Since the start of ISDN service, traffic has increased in volume and systems need to have large capacity. the TST‐type switching network is the most typical configuration to increase the system capacity. However, conventional methods for evaluating performance with multislot connections are not accurate.First, a method is proposed for a single traffic stream of multislot connections where iteration is applied to solve the traffic model with loss rates in state transitions. Next, making use of traffic stream distribution probabilities for each single‐class traffic and full availability traffic model and the offered traffic of each traffic stream, the blocking probabilities of each class of traffic for a mixed traffic stream is approximately evaluated. This method well approximates the traffic characteristic of TST switching networks and its computation time is negligible compared to the simulation.
Adaptive predictive image coding using variable block shapes controlled by edge orientation
Authors: Ebitani Kenji , Kitajima Hideo , Shirakawa Tomoaki , Ogawa Yoshihiko 
Published: July 2007

AbstractThis paper proposes adaptive predictive image coding with variable block shapes based on edge orientation, as a highly efficient coding method for low bit rates. the method aims at the improvement of reconstructed image quality in edge areas.In addition to the conventional method, where the quantizer is switched adaptively, according to the standard deviation of the prediction error signal calculated for each block 8 × 8 pixel, a predictor matched to the edge structure is used. Whenever necessary, the block is segmented into two, according to the orientation of the edge, and vector quantization is applied to the prediction error signal. When the block is segmented, the maximum number of bits assigned to each pixel is doubled if the number of representative vectors in quantization is kept the same.By this scheme, saturation of the signal‐to‐noise (SN) ratio for the high bit‐rate condition, which is observed in the conventional system, can be avoided. In the proposed system, the forementioned control is executed by table look‐up based on the standard deviation of the prediction error signal. the table is independent of the image and can be constructed beforehand with the advantage of the conventional system being inherited. the proposed method exhibits overall satisfactory coding performances over A‐VQ‐PE and A‐DCT‐VQ, which have high coding efficiency. This verifies the usefulness of the proposed method.
Asymptotic analysis of transient electromagnetic fields in a semicylindrical concave conducting boundary
Authors: Goto Keiji , Yukutake Kazutoshi , Ishihara Toyohiko 
Published: July 2007

AbstractThe propagation of the pulse wave radiated from the pulse source on a concave cylindrical conducting boundary has been studied by using asymptotic representations by: (1) a combination of the geometric optical wave and the integral‐type interference wave; and (2) a combination of the geometric optical wave and the lowest‐order whispering gallery (WG) modes.The effectiveness of the asymptotic representations is determined by comparison of the numerical results with the reference solution using a combination of the WG modes and the continuous spectrum. Also, the asymptotic method was used for deriving the complex rays on the shadow side of the caustic and the uniform asymptotic solution effective in the transition region near the caustic. It was shown that the pulse wave represented by a complex ray can reach the observation point on the shadow side of the caustic. Further, if both the source and the observation points are on or near the boundary surface, the waves due to the multiple reflection can be represented by the interference wave of an integral type or by the lowest‐order WG mode.The mutual relationship between the geometrical optics and the WG modes was determined. It was shown that the asymptotic solution in the time domain is more effective than the results in the frequency domain in the detailed analysis of the physical meaning of the wave propagation in a concave boundary.
Beam‐space CMA adaptive array antennas
Authors: Chiba Isamu , Chujo Wataru , Fujise Masayuki 
Published: July 2007

AbstractIn the communication system using a constant modulus signal, a constant modulus algorithm (CMA) adaptive array antenna is effective for elimination of the frequency‐selective fading generated in multiple propagation paths. On the other hand, in the system in which CMA adaptive loops are installed for each antenna element in an array with more than 10 elements used for mobile satellite communication, the computing time and the amount of hardware become excessive.In this paper, a beam‐space CMA adaptive array antenna (BSCMA) is proposed in which a portion of the multibeam output is selected to form a CMA adaptive array. In the BSCMA, first, a multibeam is formed by means of a fast Fourier transform (FFT) and only the beams whose output power exceeds a threshold level are selected. an adaptive process is carried out with the CMA as a guiding principle only for the selected beam outputs. the BSCMA has an advantage of carrying out the capture of the desired wave and the elimination of the interference wave effectively with degrees of freedom corresponding to the number of arriving waves. the method is effective for an adaptive antenna system applied to an array antenna constructed with many antenna elements. In this paper, the configuration of the BSCMA is shown and its characteristics are investigated by the numerical simulation.
Expansion of lightwave network rooknet: TDMA RookNet
Authors: Kato Manabu , Uchino Takeo , Oie Yuji , Miyahara Hideo 
Published: July 2007

AbstractLightwave networks based on optical wavelength division multiplexing (WDM) have been considered promising for high‐speed communication. Such lightwave networks are divided mainly into two groups according to the number of hops required for packets to arrive at their destinations: single‐hop networks and multihop networks. the authors have already proposed a lightwave mesh network RookNet, which allows packets to arrive at any node at most in two hops, by taking advantage of both single‐hop and multihop networks, and analyzed its performance. This paper proposes a scheme to enlarge the RookNet without increasing the number of receivers per node and analyzes its performance. Specifically, the TDMA scheme is used in which a pair of nodes share a channel and employed sequentially. As a result, the proposed RookNet, referred to as the TDMA RookNet, accommodates about three to four times as many nodes as the original one.
An optically controlled array antenna with a beam‐forming network (BFN) using two laser sources
Authors: Konishi Yoshihiko , Chujo Wataru , Fujise Masayuki 
Published: July 2007

AbstractWith respect to the optically controlled array antenna in which the optical Fourier transform and the O/E conversion are used for generation and control of the microwave excitation distribution in the optical region, the excitation amplitude and phase distribution and the radiation characteristics are studied theoretically and experimentally for a two‐laser system in which two laser sources with their oscillation frequency difference set at the desired microwave frequency are used.First, the excitation distribution and the radiation pattern are expressed theoretically in the case where a circular aperture image mask is used and the relationship between the image mask aperture diameter and the element antenna spacing is derived.Next, a two‐laser experimental system is shown which uses LD pumped Nd: YAG lasers as the laser sources. an excitation distribution experiment was carried out at 1.54 GHz. From the experimental results, it is found that a stable excitation distribution corresponding to the theoretical value can be obtained in the experimental system in the two‐laser system as in the one‐laser system. Further, by using the measured excitation distribution, the array radiation pattern is computed. In this way, it is confirmed that the radiation pattern in a beam shape corresponding to the image mask aperture diameter can be obtained.
Throughput analysis of a transport protocol in an FDDI network
Authors: Ishibashi Yutaka , Maruyama Mitsuru , Sakamoto Hideki 
Published: July 2007

AbstractThis paper analyzes the throughput of a transport protocol, such as the ISO transport protocol class 4 (TP4) and the transmission control protocol (TCP), in a fiber distributed data interface (FDDI) network. It also studies the influence of the target token rotation time (TTRT), ring latency, window size, and frame length on the throughput performance in cases of both symmetric traffic and asymmetric traffic. Furthermore, the throughput is compared with that of FDDI without transport protocol in order to quantify the overhead of the transport protocol. Numerical results indicate that the influence of window size and frame length on the throughput is larger than that of ITRT.
Mode‐field‐diameter measurement method using a field mask
Authors: Kuwaki Nobuo , Seino Minoru , Yoshida Koji 
Published: July 2007

AbstractIn the mask method, which is one of the measurement procedures of estimation of the mode field size of single mode optical fibers, measurement setup can easily be devised. the advantage is that the overall system is small in size. However, there are few investigations with only a few reports on the physical properties of the field mask required in realization of the measurement method or the details of applications to the dispersion shifted optical fibers used in trunk lines. the present paper investigates the required physical characteristics of the mask and it is found that in order to keep the error in the measurement of the mode field radius below, the mask attenuation must be larger than 45 dB. Further, when the required attenuation is not satisfied by the mask, the equation under which there is still the possibility of field measurement is derived. Using the derived equation, it became clear that it is possible to measure the mode field radius of the 1.3 μm band and the dispersion shifted fibers by the far field method with deviations below 1 percent. Further, when such a method is devised to fit into the far end of the fiber cables, their mode field radius can be measured when the maximum cable loss is 45 dB.
Shared output buffer‐type switching architecture with fair output port contention
Authors: Tode Hideki , Yamamoto Miki , Okada Hiromi 
Published: July 2007

AbstractThis paper considers the shared output buffertype switching system as an architecture suited to the large‐scale ATM switching system. an architecture is proposed, which can solve the fair throughput assignment problem among the ports belonging to the same shared memory, which is a problem in sharing the output buffer. the proposed architecture realizes fair access to the destination port contained in the specified shared buffer, by sort processing and the address attachment, without using the random access contention unit to the buffer in the knockout switch.For the proposed architecture and the conventional shared output buffer‐type knockout switching system, the performances are compared by deriving the cell loss probability due to the output contention for each port. As a result, it is verified that the proposed architecture is better in terms of the realized cell loss probability.The performance of the switching system is evaluated by a computer stimulation when various buffering schemes are applied to the shared output buffer. Then it is shown that the fair throughput assignment among the considered output ports can be realized by combining the proposed architecture with an adequate buffering scheme.
Performance analysis of a wireless local area network with a TDD channel taking into consideration capacity allocation between uplink and downlink channels
Authors: Suzuki Takahiro , Tasaka Shuji 
Published: July 2007

AbstractThis paper deals with a wireless LAN of microcells. We focus on a single microcell, which consists of a base station and wireless terminals. We consider here a problem of the channel capacity allocation between the uplink (terminal‐to‐base) and downlink (base‐to‐terminal) communications for a wireless LAN with a TDD (time division duplex) channel. the ALOHA‐Reservation protocol is selected as a MAC protocol for the uplink communication. the performance of the ALOHA‐Reservation protocol with a TDD channel is analyzed in terms of throughput, average message delay, and average response time. Then, the effect of the uplink and downlink channel capacities on the performance is examined under various traffic conditions.
An approach to optical parallel data transmission using optical symbolic substitution
Authors: Takahashi Hideya , Shimizu Eiji , Kajiki Yoshinori 
Published: July 2007

AbstractThis paper proposes a flexible parallel optical data transmission system as follows. the data transmission itself is executed in parallel by utilizing the super‐parallelism of the light. In addition, the address information which is necessary for the transmission is super‐posed on the transmitted data. By those schemes, the capacity of the individual transmission channel as well as the number of transmission channels in the system are made variable.This paper describes first the principle of parallel optical data transmission. It is shown that the symbolic substitution (SS) is useful in the superposition and separation of the address information, which are the basic operations of the system. SS is a parallel and positioninvariant logical operation. an experimental system is constructed by the SS technique using the computer‐generated Fourier hologram (CGFH). A result of experiment is shown for the single‐channel parallel transmission of two‐dimensional data. Thus, it is shown that the flexible transmission system, where the capacity of the individual transmission channel as well as the number of transmission channels are variable, can be realized by the proposed transmission scheme.
Receiver design using the dependence between quadrature components of impulsive radio Noise
Authors: Miyamoto Shinichi , Morinaga Norihiko , Katayama Masaaki 
Published: July 2007

AbstractIn this paper, the statistical characteristics of Middleton class A impulsive noise are investigated to obtain a receiver that is robust against impulsive radio noise. It is shown that the in‐phase and quadrature phase components of class A impulsive noise are not statistically independent though they are uncorrelated. Then a new receiver design based on the dependence between these components is proposed for class A impulsive noise. Numerical results show that the proposed receiver is quasioptimum and its performance is much better than that of a conventional receiver.
Fast frequency hopping transmitter and receiver based on digital signal processing and its performance
Authors: Sawahashi Mamoru , Adachi Fumiyuki 
Published: July 2007

AbstractFrequency hopping is an effective technique in which error correction is performed by randomizing the bust error due to fading. In this paper, frequency translation based on digital signal processing is applied and the structure of fast frequency hopping transmitter and receiver is proposed. the principles of frequency hopping modulator and frequency translating filter for hopped‐signal reception are first described. Then an experimental 1.5 GHz transmitter and receiver (128 kbps, differentially encoded /4‐shifted quadriphase‐shift keyed (QPSK), differential detection) that can hop among 96 frequencies (12.288 MHz bandwidth) are developed. It is confirmed that a frequency switching time of 2(32) s is realized at the transmitter (receiver) and that the receiver successfully frequency translates and demodulates the hopped signal within approximately 75 s. Finally, the combined effect of frequency hopping in a fading environment and with forward error correction is experimentally evaluated. the proposed structure replaces the conventional frequency synthesizers consisting of frequency divider and phase‐locked loop by fixed frequency oscillators so that fast frequency switching can be realized. Moreover, the proposed system uses very little power and is small, making it suitable for miniaturization of LSI.
Circularly polarized conical beam antennas
Authors: Kawakami Haruo , Sato Gentei , Watanabe Takeshi , Wakabayashi Ryoji 
Published: July 2007

AbstractA small and lightweight antenna was developed which generates a circularly polarized conical beam in the desired direction by changing the incline angle of the linear antenna elements and the spacing between the antenna elements without phase shifters. the experiment for directivity of the circularly polarized conical beam antenna was carried out by using four monopole antennas, and the effectiveness of the theoretical analysis was confirmed.Next, experiments were carried out for the impedance and directivity with representative dimensions. the gain in the maximum direction was 4.5 dBi with an axial ratio of less than 2 dB and a standing wave ratio of less than 1.2.
622 Mbit/s‐sixteen‐channel FDM coherent optical transmission system using two‐section MQW DFB‐LDs
Authors: Mizuochi Takashi , Shimizu Katsuhiro , Shimomura Kenkichi , Kitayama Tadayoshi , Ito Katsuyoshi , Ishimura Eitaro 
Published: July 2007

AbstractA light source and optical frequency control technique needed for realizing the optical frequency division multiplexing transmission (Optical FDM) is developed and experiments of a 622 Mbit/s‐sixteen‐channel FDM coherent optical transmission based on the heterodyne detection are conducted. the transmission is configured such that sixteen 1.55 μm wavelength two‐section MQW DFB‐laser diode (LD) are multiplexed by a star coupler. the wavelength of each LD was spaced at 10 GHz intervals with the frequency fluctuation kept under + 100 MHz by the optical frequency control circuit that uses a scanning Fabry‐Perot interferometer. the receiver configuration has a delay‐line demodulator, polarization diversity, and a frequency discriminator with no dead bands. For the station light source, the two‐section MQW DFB‐LD was tuned, which is the same as the transmitter, using current and temperature control. Random channels could selectively be received with a receiver sensitivity of ‐39.3 dBm. It was verified that 16 channels of 622 Mbit/s high‐vision (Japanese standard HDTV) signal could be transmitted through 110 km of 1.3 μm zero dispersion fiber without signal degradation.
A virtual STM transmission method based on ATM network
Authors: Kamiyama Noriaki , Ohta Chikara , Tode Hideki , Yamamoto Miki , Okada Hiromi 
Published: July 2007

AbstractThis paper considers a new transmission method (quasisynchronous transfer mode, Q‐STM), as a means to eliminate both the cell loss and the network delay fluctuation in an ATM network. the concept of time‐switch in circuit switching is introduced into the ATM switching framework. A switching structure and the call establishment procedure are proposed. In the proposed method, the time‐switch is introduced, which eliminates in principle the output port contention in the ATM switching fabric. By preparing a buffer with a certain capacity, cell loss due to buffer overflow in the output port of the ATM switch can be completely eliminated.
Asynchronous transfer mode call admission control scheme with plural quality classes
Authors: Ogino Nagao 
Published: July 2007

AbstractIn an asynchronous transfer mode (ATM) network, various calls with different trans‐mission quality requirements ranging from low bit‐rate data signals to high bit‐rate motion picture signals are applied. Therefore, it is important to determine how to allocate network resources to those calls and to judge whether those calls can be accepted. This paper proposes a call admission control scheme based upon a data table that holds the relationship between average bit‐rate and needed bandwidth for aggregated signals in each quality class obtained beforehand by simulation. This proposed scheme assumes broadband services where the aver‐age bit rate and burstiness of aggregated signals can be estimated clearly with predictable value ranges. This proposed scheme uses a conventional scheme for service quality class control. the following charac‐terizes this proposed scheme: (1) it is suitable for real time call processing because it has small table search processing and a simple table search algo‐rithm; (2) it realizes more accurate control due to a decreased data volume requirement and more precise data preparation than is the case for some of the conventional schemes; (3) it can be expanded easily to handle increases in the number of quality classes; and (4) it provides control in terms of statistic multiplexing effects between each quality class (also found in some of the conventional schemes).
Pointer conversion method for synchronous digital hierarchy
Authors: Takatori Masahiro , Nakano Yukio , Ishida Keiichi , Ashi Yoshihiro , Kanno Tadayuki , Mori Takashi 
Published: July 2007

AbstractSynchronous digital hierarchy (SDH) standardized in International Telecommunication Union‐Telecommunication Standard Sector (ITU‐T) applies a new multiplexing method using a pointer that indicates a tributary location in the SDH frame. the location of the SDH frame heads received from several lines is adjusted at interface circuits to facilitate the multiplexing process in the SDH equipment. Since the frame head locations of input signal differ from the output signal, pointer values are attached to the output signals. the pointer conversion of each tributary is performed independently of each other. Therefore the pointer values of tributaries transported on the same line might be different from each other after the conversion even if these values are the same. Hence large amounts of buffer memory would be required at the destination point to provide a transport service utilizing multiple virtual containers (VCs). This paper proposes a new pointer conversion method that keeps the pointer value differences unchanged between tributaries multiplexed in an SDH frame. This method allows multiple VC transport service to be provided.