ISSN:1124-318X    

DOI:10.1002/ett.4460030502

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

年代:1992

数据来源: WILEY

摘要:

AbstractLaurent's representation of binary continuous phase modulations (CPMs) based on real impulses of finite duration is advantageous for the signal generation in the transmitter as well as the signal processing in the detector.In the present paper, a novel algorithm for the determination of these impulses in simulation and experiment by the excitation of certain modulator responses shall be illustrated. The algorithm is an interesting alternative to conventional signal processing applying phase detection, thus allowing further insight in the nature of binary CPM.

ISSN:1124-318X    

DOI:10.1002/ett.4460030503

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

年代:1992

数据来源: WILEY

摘要:

AbstractAn automatic‐repeat‐request (ARQ) scheme with memory is described in which the received vectors, even when detected in error, are retained to facilitate the correct recovery of the transmitted message. The optimization of the system parameters with the transmission channel affected by fading have been derived theoretically. The results of computer simulations performed to evaluate throughput show considerable improvement with respect to the classical ARQ protocols, making the proposed scheme especially suitable for mobile communicati

ISSN:1124-318X    

DOI:10.1002/ett.4460030504

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

年代:1992

数据来源: WILEY

摘要:

AbstractArray error control codes are linear block or convolutional codes which are constructed from several single parity check or other component codes, assembled in two or more geometrical dimensions or directions, with emphasis on simple component codes and low complexity methods of decoding. This survey attempts to introduce, relate and compare all known types of array codes and their applications. After an introduction to the basic properties and uses of array codes, the second section of the paper describes binary array code constructions for random, burst and cluster error control. The third section describes a number of binary convolutional array codes, for both random and burst error control. Non‐binary and byte‐oriented array codes, both block and convolutional, are covered in the fourth section, which mentions some quite powerful and yet practical constructions. The fifth section discusses various enhancements which can be applied to array codes. The paper ends with conclusions, open problems, and an extensive set of referen

ISSN:1124-318X    

DOI:10.1002/ett.4460030505

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

年代:1992

数据来源: WILEY

摘要:

AbstractA new description is developed for handwritten character recognition for Western style characters. Character recognition here is based on Generalised Fourier Descriptors (GFDs). The characters are described by sections which are either straight line pieces or arcs of circles. Analytical expressions exist for the GFDs of these two types of curves. In order to apply these expressions on handwritten characters, these characters are first curve‐fitted into straight line‐pieces and arcs of circles. After this description the GFDs can easily be calculated. Experiments were performed and preliminary, qualitative remarks on these are m

ISSN:1124-318X    

DOI:10.1002/ett.4460030506

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

年代:1992

数据来源: WILEY

摘要:

AbstractKnowledge‐Based (K‐B) approaches to Computer Vision seem to have come to a stalemate, due to difficulties inherent in performing crucial activities, e.g., autonomous refinement of the embedded high‐level knowledge and time‐consuming low‐level processing. In the paper, the problem is related to a broader class of issues, and the conclusion is drawn that no individual method can be regarded as a unique and comprehensive paradigm for Computer Vision. A possible solution to this problem might lie in combining different methodologies to enhance mutual advantages and to balance individual shortcomings; K‐B vision approaches are reviewed here from this integration‐oriented perspective. Higher‐level integration should aim at improving 'intelligent' activities of K‐B systems; Machine Learning approaches to Vision are discussed from this point of view, Lower‐level integration should provide K‐B systems with the fast number‐crunching capability and robustness required; the use of neural networks and of associative memories is evaluated for this purpose. All such methodologies are reviewed, taking into account both their intrinsic peculiarities and the specific problems that may arise from coupling them with K‐B vision systems. The paper aims at providing an updated and critical picture of some lines of research that are currently being pursued to achieve an efficient integration of K‐B techniques

ISSN:1124-318X    

DOI:10.1002/ett.4460030507

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe zero input limit cycle behavior of canonical second order sections of digital filters using a certain kind of Residue Number System (RNS) arithmetic are investigated. It is shown that constant and period two limit cycles are frequent in a large part of the linear stability triangle. Therefore, the designer should either modify the overflow and quantization characteristic, or use filter structures that are not plagued with limit cycles.

ISSN:1124-318X    

DOI:10.1002/ett.4460030508

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

年代:1992

数据来源: WILEY

摘要:

AbstractThis contribution presents the software tool REFORMA, which will support the tasks of telecommunication network planning departments. It is shown that REFORMA offers various possibilities for circuit demand routing, grouping and stand‐by network optimization applied to local and trunk networks with digital transmission systems. The large flexibility to implement different planning rules and network development strategies with REFORMA is demonstrated by some network examples. Further extensions and applications of this tool are also indicate

ISSN:1124-318X    

DOI:10.1002/ett.4460030509

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

年代:1992

数据来源: WILEY

摘要:

AbstractBroadband ISDN (B‐ISDN) offers new facilities for video transmission. Asynchronous Transfer Mode (ATM) is suitable for integrating different types of services (data, voice, video) and ensures a new flexibility of the network relatively to traffic control and resources utilization. As a drawback delays and losses of packets are to be considered. A basic step to valutate such performance parameters is the estimation of models of packet production of each data source contending network resources. In this paper a model, not strictly frame buffered, accounting of the bit rate generated by a compressed video source is proposed and its validity is assessed by fitting it to true bit rate data from a DCT video coder. Simulations of the modeled video source as input to an ATM multiplexer, together with other kinds of traffics, are presented to investigate the performance of the networ

ISSN:1124-318X    

DOI:10.1002/ett.4460030510

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

年代:1992

数据来源: WILEY

摘要:

AbstractIn the planning of circuit‐switched networks the decisions regarding the capacity of transmission and switching equipments, the location of exchanges and the routing principles are of primary importance. Traditionally planning methods were based on heuristic type algorithms using sometimes simple mathematical programming algorithms for particular sub‐problems. However in the 70's and 80's, new approaches based on mathematical programming algorithms (namely non‐linear programming, integer programming and dynamic programming algorithms) have been put forward for solving some key telecommunication network planning problems.The main objective of the paper is to identify the main characteristics of problems where mathematical programming has been applied (in the context of circuit‐switched network planning) and referring to relevant works in these areas. A system of taxonomic classification of circuit‐switched network planning problems is proposed and applied to an extensive list of relevant publications complemented with a list of correlated papers and other publications. The core of the overview of contributions, presented in the paper, will be limited to models of operational planning of circuit‐switched networks. Finally the authors, based on their own experience in specific problems, will try to put forward some general conclusions of a broad methodolog

ISSN:1124-318X    

DOI:10.1002/ett.4460030511

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

年代:1992

数据来源: WILEY