摘要:

AbstractBlock truncation coding is a highly efficient compression coding for the natural picture. It is useful in reducing the cost for storage and transmission of full‐color still pictures, such as those in the picture data base and the videotex. In the application of the highly efficient compression coding to the practical system, it is required to adjust the coding complexity and the picture quality, according to the cost and quality of the service provided by the system. From such a viewpoint, this paper discusses the control of the coding parameters, which determine the coding condition, and then the optimization of the coding parameters, to arrive at the coding complexity and the picture quality to meet the requirement.First, the traditional adaptive block truncation coding is extended to improve the coding efficiency and to expand the realizable range of coding complexity and picture quality. Then the control of coding is discussed which determines the coding parameter values in an adaptive and automatic way, according to the required picture quality and the property of the object picture in the considered system, to arrive at the desired quality. It is shown that it is possible to realize the coding with the desired quality simply by specifying SNR, independently of the property of the object pictur

ISSN:8756-6621    

DOI:10.1002/ecja.4410730201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractFor high‐efficiency image compression, previously, an SVD (singular value decomposition)‐based coder was developed using vector quantization, called SVD‐VQ. This paper proposes an improved quantization SVD‐VQ scheme. For every input subblock, the SVD‐VQ coder scalar‐quantizes a singular value and vector‐quantizes two singular vectors, separately. The SVD‐VQ decoder reproduces a subblock as the product of these quantization outputs, but does not necessarily produce a reconstruction with the minimum distortion in an image space. This paper develops a quantization scheme where the minimum‐distortion reconstruction is always provided in the original image space and presents its design algorithm. The improved SVD‐VQ shows A/N performance improvement of 0.5 ‐ 1.0 dB over the conventional SVD‐VQ, and is similar in performance to the adaptive DCT (discrete

ISSN:8756-6621    

DOI:10.1002/ecja.4410730202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of the number of significant digits on the demodulator output noise is analyzed and examined by a simulation in relation to the FM broadcasting system specification. The quantization noise Nqgenerated at A‐D conversion of IF signals is regarded as a white Gaussian noise similar to the thermal noise Nzfed to a receiver input. From the condition of C/Nzsatisfying the broadcasting specification, Nqsuch that NqNi‐ 10 [dB] is obtained and then the quantization precision satisfying this condition (being translated into the precision at the output of a digital signal processing demodulator) is obtained. As a numerical example, it is shown that only 6‐ and 9‐bit precisions are necessary for monophonic and stereophonic reception, respectively. The simulation result agrees with the numerical result. Reduction in the number of filter taps at the demodulator with the introduction of a window function is also studied. Given the system specification, the obtained result is also applicable for digital FM demodulators of

ISSN:8756-6621    

DOI:10.1002/ecja.4410730203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA new network design algorithm called “NABLE” (network constructing algorithm based on link significance evaluation) is proposed for constructing future circuit‐switched telecommunications networks. First, this algorithm creates synthetically a backbone network by utilizing a new concept called “link significance.” Then it adds other links to the created network. The flowchart for constructing a network based on this concept is explained. Design examples on digital 64 kbit/s and high‐speed/ broadband circuit‐switched networks show that NABLE is a powerful heuristic algorithm for total network optimization. NABLE can be used in practice for the long‐range planning of various ty

ISSN:8756-6621    

DOI:10.1002/ecja.4410730204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractTransmission channels in mobile communication are extremely unstable due to the effect of multipath fading. Therefore the realization of high‐reliability communication necessitates the introduction of error control in the form of error‐correction coding.This paper considers the decoding of error‐correcting codes that are adapted to digital mobile communication operating under Rayleigh fading conditions. A soft decision Viterbi decoding using the received carrier level is studied for the case of convolutional codes. This soft decision method is based on the level of the received carrier by adaptively determining the metric used in the decoding. In this way a metric is obtained for digital mobile communication.This paper also presents an estimation method using error exponent which provides effective means to realize such a soft decision method. If the channel can be considered memoryless due for example to interleaving, then this method provides an easy way to estimate: (1) the figure of merit for quantizing thresholds, and (2) the gains of the soft decision.First, it is shown that using this kind of estimation in the case of channels which can be considered sufficiently memoryless due to interleaving, extremely large gain is obtained by the soft decision method discussed in this paper.Next, simulations are performed and the efficiency of the estimation method is demonstrated. Finally, the bit error rate characteristics are shown for the case when the channel is not made sufficiently memoryless by interle

ISSN:8756-6621    

DOI:10.1002/ecja.4410730205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper proposes a new multimedia burst multiplex system for efficiently multiplexing such multimedia signals as speech and image on the digital channel. The performance is analyzed by approximation. The signals for each medium are encoded, put into packets, and stored in the buffer memory. The controller shared by media monitors the number of packets in the buffer memory as well as the maximum waiting time. The results are weighted for evaluation; and, according to the proposed rule, the packets are sent out to the line. By an approximate analysis, the proposed system is compared with FIFO and another system with priorities. It is seen that the proposed system, in terms of the performance, is in between FIFO and the priority systems. It can control and prioritize according to the property and state of the media, and is suited to multiplexing of media with various properties.

ISSN:8756-6621    

DOI:10.1002/ecja.4410730206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractIn multimedia telecommunication, multidimensional traffic is formed, where signals such as voice, data and image exist on the same system. It is known that the traffic characteristics are different in such a case from those of the one‐dimensional traffic based on telephone calls. However, no quantitative study has been made on such traffic characteristics. This paper considers the two‐dimensional traffic of the loss system where two classes of calls exist: basic and wide‐band. The loss characteristics are derived and provide a guide for the design including wide‐ban

ISSN:8756-6621    

DOI:10.1002/ecja.4410730207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractIt is known by experience that a single‐layer star wiring network is suited for the design of premises distribution network with a small number of terminals. On the other hand, it is anticipated that the star wiring network with more than one layer will be better when there are a large number of terminals. In the design of the star wiring network with more than one layer, there are a number of parameters to be determined, e.g. the number of nodes, the placement of nodes, and the reduction of cables. However, no method has been presented by which the optimal distribution network configuration can be determined. This paper aims at the determination of the optimal configuration for the premises distribution network with two‐layer star structure. A model is presented for the modified two‐layer star wiring network, including anew the tandem connection. The cost function is derived, and the network configuration is determined to minimize the cost function. As a result, parameters which are important in the design can be determined for the practical rectangular area, where the important design parameters such as the number of nodes, the placement of nodes and the necessity for reducing the cable, are determined from the given area size and the number of term

ISSN:8756-6621    

DOI:10.1002/ecja.4410730208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractFor the OSI message exchange protocol, the MHS (message handling system) was recommended in 1984 by CCITT. The implementation of this protocol is being considered by network service enterprises and computer manufacturers in various countries. MHS is constructed as an application of OSI common application protocol. ROS (remote operations service) and RTS (reliable transfer service), specified by MHS, and performing the acknowledgement of send/receive of application data and the interruption/recovery, can also be used in common with other applications of OSI. This paper presents an analysis and evaluation of ROS and RTS from the viewpoint of the number of transmitted/received packets and the transfer time. The relation between the window size and the transfer efficiency in RTS is derived. For the system combining ROS and RTS, the method for controlling the window size corresponding to the response time, as well as the method for setting the session data length corresponding to the interruption rate, are presented. As to the method of combining ROS and RTS, it is shown that a large amount of application data can be transferred in a stable way, even if the interruption rate is large, by applying RTS to ROS.

ISSN:8756-6621    

DOI:10.1002/ecja.4410730209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractTo cope with the increasing demands for the land mobile communication with a limited frequency band, it is necessary to improve the spectral efficiency beyond the present state. QAM (quadrature amplitude modulation) is one of the effective means for this purpose. When QAM is applied to land mobile communication, however, a great distortion is produced in the envelope and the phase due to fading fluctuation. Because of this property, few discussions have been made on the application of QAM to land mobile communication. This paper proposes the following system for such an application. The fading distortion is measured from the periodically inserted known frame symbol. By interpolating the obtained time‐series, the fading distortion for all symbols is estimated. Then the distortion is compensated. The performance when the proposed method is applied to 16QAM is examined by computer simulation. It is seen as a result that the fading distortion can be compensated with high accuracy, making 16QAM applicable to land mobile communication

ISSN:8756-6621    

DOI:10.1002/ecja.4410730210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY