ISSN:1124-318X    

DOI:10.1002/ett.4460030102

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

年代:1992

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460030103

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

年代:1992

数据来源: WILEY

摘要:

AbstractThree different approaches to FDM demultiplexing applying digital signal processing are investigated forL0= 32 slot signals: The single stage method (SSM), the polyphase method (PPM), and the hierarchical multistage method (HMM). All three approaches apply bandpass sampling and are based on the processing of complex signals by linear‐phase FIR filters, where the respective signals are always oversampled by a factor of two at any stage of processing. For the three methods all relevant design results are given including the required fixed‐point signal and coefficient wordlengths.The HMM is the most efficient of the above approaches in terms of (bit) operation rate per channel, immediately followed by the PPM, while the SSM is less efficient by a factor of ten. Additional advantages claimed for the HMM are its high degree of modularity with the potential of optimization, ease of manufacturing and testing, suitability for VLSI realization, high reliability, and reduced amount of overhead circuitry.This paper is published in two parts. Part I comprises the introduction, the front end issues common to all three approaches to FDM demultiplexing and the treatment of the SSM. In Part II the work on the PPM and the HMM is reported. Furthermore, all three approaches are compared with each other and a conclusion is gi

ISSN:1124-318X    

DOI:10.1002/ett.4460030104

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

年代:1992

数据来源: WILEY

摘要:

AbstractThree different approaches to FDM demultiplexing applying digital signal processing are investigated forL0= 32 slot signals: The single stage method (SSM), the polyphase method (PPM), and the hierarchical multistage method (HMM). All three approaches apply bandpass sampling and are based on the processing of complex signals by linear‐phase FIR filters, where the respective signals are always oversampled by a factor of two at any stage of processing. For the three methods all relevant design results are given including the required fixed‐point signal and coefficient wordlengths.The HMM is the most efficient of the above approaches in terms of (bit) operation rate per channel, immediately followed by the PPM, while the SSM is less efficient by a factor of ten. Additional advantages claimed for the HMM are its high degree of modularity with the potential of optimization, ease of manufacturing and testing, suitability for VLSI realization, high reliability, and reduced amount of overhead circuitry.This paper is published in two parts. Part I comprises the introduction, the front end issues common to all three approaches to FDM demultiplexing and the treatment of the SSM. In Part II the work on the PPM and the HMM is reported. Furthermore, all three approaches are compared with each other and a conclusion is gi

ISSN:1124-318X    

DOI:10.1002/ett.4460030105

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe performance of underlying Hamming codes in M‐QAM digital radio systems is analyzed in the presence of nonlinear distortions.An effective soft‐decision decoding algorithm is constructed to reduce the number of errors induced by the nonlinear and noisy channel.Then the residual bit error probability is calculated from the statistical estimations of the detector input samples. It is shown that for weakly and moderately nonlinear channels error correction coding can significantly improve the system performa

ISSN:1124-318X    

DOI:10.1002/ett.4460030106

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe paper deals with the detection of a known signal embedded in cyclostationary white generalized Gaussian noise. Two cases are considered: the former assumes unknown (but nonrandom) the periodic noise intensity, the latter considers unknown also the noise‐shape parameter. Since for these detection problems non uniformly most powerful test exists, the generalized log‐likelihood ratio test (GLLRT) is considered because of its asymptotic optimality properties. The GLLRT‐based detectors for both cases are synthesized and their asymptotic (i.e., for large sample size) performances are analytically evaluated. Moreover, for finite sample size, the performances, carried out via computer Monte Carlo simulations, are compared with that of the optimum detector, whose synthesis is based on a complete noise characteriz

ISSN:1124-318X    

DOI:10.1002/ett.4460030107

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe problem of optimal nonbifurcated routing in virtual circuit (VC) communication networks, such as the X.25 packet‐switched networks, the frame‐relay networks or the ATM networks, is considered. To describe the related characteristic of the generally asymmetrical transmit and receive traffic in such networks, a related multicommodity flow (RMCF) model with two traffic matrices is proposed. For solving the optimal flow assignment problem with this model, we present an algorithm which incorporates the transmit receive (TR) relation, an important practical constraint existing in most of the operational VC networks.A comparison of the RMCF model with the symmetrical multicommodity flow (SMCF) model shows that the former is superior with respect to the network delay. Furthermore, performance degradation has been observed, which is caused by using the traditional multicommodity flow (MCF) model due to the lack of VC bandwidth reservation of the receive traffic. We also show the dependency of the network throughput on the traffic symmetry versus the TR ra

ISSN:1124-318X    

DOI:10.1002/ett.4460030108

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

年代:1992

数据来源: WILEY

摘要:

AbstractMajor changes are likely to occur in the telecommunications infrastructure. Both researchers and standardisation institutes are hard at work paving the way for a Broadband Integrated Services Digital Network (B‐ISDN). At one time it was widely assumed in the telecommunications world that once such a network had been established, customers would feel the need for a home network, which could be used for a wide range of purposes. However, a recent review of developments has made it very clear that the equipment which people have in their homes ‐ including telecommunications equipment ‐ falls into the category of consumer electronics. Consequently, the introduction of home networks for the private consumer will proceed in a rather less orderly fashion than telecommunications experts used to

ISSN:1124-318X    

DOI:10.1002/ett.4460030109

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

年代:1992

数据来源: WILEY

摘要:

AbstractParticular situations of pointer overflows, which can take place either in the presence of high amplitude wander on STM‐Nsignals entering SDH network elements or under severe failure conditions of the synchronization network, have been identified. In these situations waste of data results if no proper actions are carried out to handle pointer overflows. With reference to current regulations additional rules are proposed in order to avoid this kind of impairment on transported tributarie

ISSN:1124-318X    

DOI:10.1002/ett.4460030110

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe ability of a recently proposed birefringent all optical fiber filter in obtaining tunable wavelength selection is demonstrated using Stimulated Raman Scattering light. Three kinds of light: the pump light, the first order Stokes line and the second order Stokes line of a Nd:YAG laser have been extracted separately.

ISSN:1124-318X    

DOI:10.1002/ett.4460030111

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

年代:1992

数据来源: WILEY