Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02707.X
J. McKenna, N. Schryer
The potentials and fields in a two-dimensional model of a charge-coupled device (CCD) are studied. We assume no mobile minority carriers have been injected into the CCD and that the electrode voltages do not vary with time. The nonlinear equations describing the devices are first linearized using the depletion layer approximation. The linearized equations are then solved approximately by a fitting technique. Both surface and buried channel CCD's are considered. The accuracy and cost of obtaining the solution is discussed. This work is a continuation of a study initiated in an earlier paper.1
{"title":"Information Management System: The potential in a charge-coupled device with no mobile minority carriers","authors":"J. McKenna, N. Schryer","doi":"10.1002/J.1538-7305.1973.TB02707.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02707.X","url":null,"abstract":"The potentials and fields in a two-dimensional model of a charge-coupled device (CCD) are studied. We assume no mobile minority carriers have been injected into the CCD and that the electrode voltages do not vary with time. The nonlinear equations describing the devices are first linearized using the depletion layer approximation. The linearized equations are then solved approximately by a fitting technique. Both surface and buried channel CCD's are considered. The accuracy and cost of obtaining the solution is discussed. This work is a continuation of a study initiated in an earlier paper.1","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"17 1","pages":"1765-1793"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88495892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02709.X
R. Walk, J. Rootenberg
Because of its theoretical and practical interest, the stability problem in pulse-width-modulated feedback systems has received an enormous amount of attention. Much of the reported literature deals with highly approximate methods, and the exact approaches, based on Lyapunov's direct method or functional analysis, are quite restrictive and do not easily lend themselves to systematic compensation or design. In this paper, a quite general PWM is considered, and a frequency domain stability criterion is presented, yielding a geometric interpretation in the Popov plane.
{"title":"Stability of a general type of pulse-width-modulated feedback system","authors":"R. Walk, J. Rootenberg","doi":"10.1002/J.1538-7305.1973.TB02709.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02709.X","url":null,"abstract":"Because of its theoretical and practical interest, the stability problem in pulse-width-modulated feedback systems has received an enormous amount of attention. Much of the reported literature deals with highly approximate methods, and the exact approaches, based on Lyapunov's direct method or functional analysis, are quite restrictive and do not easily lend themselves to systematic compensation or design. In this paper, a quite general PWM is considered, and a frequency domain stability criterion is presented, yielding a geometric interpretation in the Popov plane.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"18 1","pages":"1811-1819"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72841524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02713.X
M. Subramanian, K. O'brien, P. J. Puglis
Measurements of phase and amplitude dispersion over a 20-MHz band have been made on a 42-km, 6-GHz, line-of-sight microwave link. A novel technique is introduced for measuring the phase dispersion induced by the propagation path. Specifically, the amplitudes and relative phases of four tones separated equally by 6.6 MHz have been continuously monitored over a period of four months. The data show that there is usually measurable (0.02 degree/(MHz)2) phase distortion over the 20-MHz band during those fades whose depth exceeds about 20 dB. These dispersive fades, which usually last a few seconds, typically occur along with shallow and essentially nondispersive fades that have durations of several minutes. However, only the dispersive fades exhibit a phase nonlinearity. Analysis of 16 events measured in the autumn of 1970 yield the following results. (i) The distribution curve describing the fraction of time that phase nonlinearity (quadratic) exceeds a given value follows a lognormal distribution. (ii) The quadratic phase nonlinear coefficient exceeds an average value of 0.1 degree/(MHz)2 for fades with depth larger than 34 dB from the nominal level. This corresponds to a time delay distortion of 0.55 nanosecond over 1-MHz band. (iii) The correlation between log-amplitude and phase nonlinear coefficients yields a correlation coefficient whose magnitude is fade-depth dependent and whose sign varies from event to event. The experimental technique of measuring phase dispersion reported here may be of interest not only for propagation studies but also in other systems such as measurement of characteristics of electrical networks. The statistical results obtained on the phase characteristics may prove of interest in formulating an analytical model. Further, they may be of significance in the design of existing and future microwave systems.
{"title":"Phase dispersion characteristics during fade in a microwave line-of-sight Radio channel","authors":"M. Subramanian, K. O'brien, P. J. Puglis","doi":"10.1002/J.1538-7305.1973.TB02713.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02713.X","url":null,"abstract":"Measurements of phase and amplitude dispersion over a 20-MHz band have been made on a 42-km, 6-GHz, line-of-sight microwave link. A novel technique is introduced for measuring the phase dispersion induced by the propagation path. Specifically, the amplitudes and relative phases of four tones separated equally by 6.6 MHz have been continuously monitored over a period of four months. The data show that there is usually measurable (0.02 degree/(MHz)2) phase distortion over the 20-MHz band during those fades whose depth exceeds about 20 dB. These dispersive fades, which usually last a few seconds, typically occur along with shallow and essentially nondispersive fades that have durations of several minutes. However, only the dispersive fades exhibit a phase nonlinearity. Analysis of 16 events measured in the autumn of 1970 yield the following results. (i) The distribution curve describing the fraction of time that phase nonlinearity (quadratic) exceeds a given value follows a lognormal distribution. (ii) The quadratic phase nonlinear coefficient exceeds an average value of 0.1 degree/(MHz)2 for fades with depth larger than 34 dB from the nominal level. This corresponds to a time delay distortion of 0.55 nanosecond over 1-MHz band. (iii) The correlation between log-amplitude and phase nonlinear coefficients yields a correlation coefficient whose magnitude is fade-depth dependent and whose sign varies from event to event. The experimental technique of measuring phase dispersion reported here may be of interest not only for propagation studies but also in other systems such as measurement of characteristics of electrical networks. The statistical results obtained on the phase characteristics may prove of interest in formulating an analytical model. Further, they may be of significance in the design of existing and future microwave systems.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"46 1","pages":"1877-1902"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85973945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02712.X
D. Henderson
The additional optical power required at the repeater input in a fiber optic communication system due to intersymbol interference is experimentally measured. In the experiment, the intersymbol interference which results from differential mode delay in multimode fibers is minimized with a five-tap transversal equalizer. Error rate measurements are performed using five fibers ranging from 0.01 km to 1.25 km in length. In this manner, the additional optical power required to achieve a given error rate is found as a function of pulse width. The measured values compare favorably with the power penalties predicted by Personick. The trade-off between excess optical power and equalization penalty in dispersion-limited fiber systems is discussed.
{"title":"Dispersion and equalization in fiber optic communication systems","authors":"D. Henderson","doi":"10.1002/J.1538-7305.1973.TB02712.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02712.X","url":null,"abstract":"The additional optical power required at the repeater input in a fiber optic communication system due to intersymbol interference is experimentally measured. In the experiment, the intersymbol interference which results from differential mode delay in multimode fibers is minimized with a five-tap transversal equalizer. Error rate measurements are performed using five fibers ranging from 0.01 km to 1.25 km in length. In this manner, the additional optical power required to achieve a given error rate is found as a function of pulse width. The measured values compare favorably with the power penalties predicted by Personick. The trade-off between excess optical power and equalization penalty in dispersion-limited fiber systems is discussed.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"50 1","pages":"1867-1876"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88346732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02715.X
J. Morrison, T. Chu
In a recent note1 calculated results of differential attenuation and differential phase shift, as a function of rain rate, were given at frequencies of 4, 18.1, and 30 GHz. The calculations have since been done at 11 GHz also. These results are based on scattering of a plane electromagnetic wave by oblate spheroidal raindrops. The point matching procedure used to obtain nonperturbative solutions to the problem was briefly described, and full details will be presented later.2 Somewhat similar calculations have been carried out by Oguchi2 at 19.3 and 34.8 GHz.
{"title":"B.S.T.J. Brief: Perturbation calculations of rain-induced differential attenuation and differential phase shift at microwave frequencies","authors":"J. Morrison, T. Chu","doi":"10.1002/J.1538-7305.1973.TB02715.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02715.X","url":null,"abstract":"In a recent note1 calculated results of differential attenuation and differential phase shift, as a function of rain rate, were given at frequencies of 4, 18.1, and 30 GHz. The calculations have since been done at 11 GHz also. These results are based on scattering of a plane electromagnetic wave by oblate spheroidal raindrops. The point matching procedure used to obtain nonperturbative solutions to the problem was briefly described, and full details will be presented later.2 Somewhat similar calculations have been carried out by Oguchi2 at 19.3 and 34.8 GHz.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"27 1","pages":"1907-1913"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90839174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02704.X
T. A. Gibson, P. F. Stockhausen
MASTER LINKS is a software system used to build, administer, and access hierarchical data bases. It is designed to operate in a time-sharing environment, and, in particular, it allows multiple concurrent updates and retrievals on the same data base. A BUILD module is used to specify the hierarchical configuration of a data base and an initial “storage mapping” of the elements of the hierarchy into a particular file layout. A set of administrative routines is provided for altering the mapping and other such maintenance purposes. The access routines have three levels of interface, from primitive and flexible to sophisticated and functional. The interfaces are all defined in terms of the hierarchical structure and independent of the storage mapping. Thus, an alteration of the storage mapping for a data base does not require changing any programs that access data using these interfaces. The lowest-level interface enables the calling program to add to the data base, update a value, or retrieve a value, in terms of a hierarchy position. The second-level interface facilitates traversal of a hierarchy by enabling the calling program to specify portions of the hierarchy over which a process is to operate. Such a specification, called an “access tree,” consists of data which can be generated at execution time by the calling routine. As in the first level, data are transferred one at a time. The third-level interface is a function evaluation mechanism which computes values from data base values and other computed values according to function definitions passed to it at execution time. Like an access tree, a function definition is itself data which can be constructed at execution time by the client process.
{"title":"Information Management System: Master links — a hierarchical data system","authors":"T. A. Gibson, P. F. Stockhausen","doi":"10.1002/J.1538-7305.1973.TB02704.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02704.X","url":null,"abstract":"MASTER LINKS is a software system used to build, administer, and access hierarchical data bases. It is designed to operate in a time-sharing environment, and, in particular, it allows multiple concurrent updates and retrievals on the same data base. A BUILD module is used to specify the hierarchical configuration of a data base and an initial “storage mapping” of the elements of the hierarchy into a particular file layout. A set of administrative routines is provided for altering the mapping and other such maintenance purposes. The access routines have three levels of interface, from primitive and flexible to sophisticated and functional. The interfaces are all defined in terms of the hierarchical structure and independent of the storage mapping. Thus, an alteration of the storage mapping for a data base does not require changing any programs that access data using these interfaces. The lowest-level interface enables the calling program to add to the data base, update a value, or retrieve a value, in terms of a hierarchy position. The second-level interface facilitates traversal of a hierarchy by enabling the calling program to specify portions of the hierarchy over which a process is to operate. Such a specification, called an “access tree,” consists of data which can be generated at execution time by the calling routine. As in the first level, data are transferred one at a time. The third-level interface is a function evaluation mechanism which computes values from data base values and other computed values according to function definitions passed to it at execution time. Like an access tree, a function definition is itself data which can be constructed at execution time by the client process.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"4 1","pages":"1691-1724"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87666008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02706.X
L. E. Heindel, J. T. Roberto
The Off-The-Shelf System (OTSS) is a packaged information management system for hierarchical data bases. OTSS provides, without computer programming, processes to enter and alter data in such a data base, do complex retrievals of data from the data base, and specify various security mechanisms to limit access to, or alteration of, a data base. OTSS also provides a mechanism for extending the available processes on a project-by-project basis. OTSS has been implemented using MASTER LINKS and the NATURAL DIALOGUE SYSTEM.
{"title":"Information Management System: The off-the-shelf system — a packaged information management system","authors":"L. E. Heindel, J. T. Roberto","doi":"10.1002/J.1538-7305.1973.TB02706.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02706.X","url":null,"abstract":"The Off-The-Shelf System (OTSS) is a packaged information management system for hierarchical data bases. OTSS provides, without computer programming, processes to enter and alter data in such a data base, do complex retrievals of data from the data base, and specify various security mechanisms to limit access to, or alteration of, a data base. OTSS also provides a mechanism for extending the available processes on a project-by-project basis. OTSS has been implemented using MASTER LINKS and the NATURAL DIALOGUE SYSTEM.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"50 4","pages":"1743-1763"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72565986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02708.X
K. Thornber
We calculate the probability of error in detecting digital signals transferred through a charge transfer device in the presence of incomplete charge transfer, random noise in the device, and detection uncertainty in the detector. The coefficient of incomplete charge transfer is assumed to be independent of charge-packet size, and both the device noise and detector noise are assumed to be Gaussian. Error probabilities for two-level and four-level codes are computed for the cases of both simple static and optimum dynamic detection. For rms detection voltage level fluctuations V d of the order of tenths of volts (much larger than the random noise fluctuations in the device), a very rapid increase in error probability (from ≍ 10−20 to ≍ 10−5) is found to occur for a very small (20 percent) change in V d . This indicates that detection level fluctuations will have to be held down to a few hundred millivolts at most. To achieve equal error rates with an error probability of about 10−14, V d for the detection of four-level codes will have to be about 3.5 times smaller than for two-level codes. Comparison of error probabilities under static and dynamic detection shows that in CTD's improved detection has a greater potential for reducing error rates than improved coding.
{"title":"Error rates of digital signals in charge transfer devices","authors":"K. Thornber","doi":"10.1002/J.1538-7305.1973.TB02708.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02708.X","url":null,"abstract":"We calculate the probability of error in detecting digital signals transferred through a charge transfer device in the presence of incomplete charge transfer, random noise in the device, and detection uncertainty in the detector. The coefficient of incomplete charge transfer is assumed to be independent of charge-packet size, and both the device noise and detector noise are assumed to be Gaussian. Error probabilities for two-level and four-level codes are computed for the cases of both simple static and optimum dynamic detection. For rms detection voltage level fluctuations V d of the order of tenths of volts (much larger than the random noise fluctuations in the device), a very rapid increase in error probability (from ≍ 10−20 to ≍ 10−5) is found to occur for a very small (20 percent) change in V d . This indicates that detection level fluctuations will have to be held down to a few hundred millivolts at most. To achieve equal error rates with an error probability of about 10−14, V d for the detection of four-level codes will have to be about 3.5 times smaller than for two-level codes. Comparison of error probabilities under static and dynamic detection shows that in CTD's improved detection has a greater potential for reducing error rates than improved coding.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"151 1","pages":"1795-1809"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77770012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02703.X
D. Chai, J. M. Wier
This paper and the following three describe computer systems to store, retrieve, and manipulate information. These have all utilized time-shared computer systems. All have evolved toward a system constructed of modular component parts and having a high degree of user interaction. Considerable attention has been given to implementation in a form suitable for simple transfer to systems of adequate capability with minimal programming effort. The data bases involved are all hierarchical in organization. The major parts are a language facility, a data base manager, a processing package, and numerous coordinated administration functions. The parts are currently assembled into a package which can be applied to an arbitrary hierarchically structured data base with little user effort. The component parts are also available for integration into more tailored systems for special applications.
{"title":"Information management system: Interactive information management systems","authors":"D. Chai, J. M. Wier","doi":"10.1002/J.1538-7305.1973.TB02703.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02703.X","url":null,"abstract":"This paper and the following three describe computer systems to store, retrieve, and manipulate information. These have all utilized time-shared computer systems. All have evolved toward a system constructed of modular component parts and having a high degree of user interaction. Considerable attention has been given to implementation in a form suitable for simple transfer to systems of adequate capability with minimal programming effort. The data bases involved are all hierarchical in organization. The major parts are a language facility, a data base manager, a processing package, and numerous coordinated administration functions. The parts are currently assembled into a package which can be applied to an arbitrary hierarchically structured data base with little user effort. The component parts are also available for integration into more tailored systems for special applications.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"272 1","pages":"1681-1689"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76404272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1973-12-01DOI: 10.1002/J.1538-7305.1973.TB02710.X
D. Falconer, G. Foschini
Decision feedback equalization is presently of interest as a technique for reducing intersymbol interference in high-rate PAM data communications systems. The basic principle is to cancel out intersymbol interference arising from previously decided data symbols at the receiver, leaving remaining intersymbol interference components to be handled by linear equalization. In this work we consider the application of decision feedback equalization to quadrature-amplitude modulation (QAM) transmission, in which two independent information streams modulate quadrature carriers. Extending Salz's treatment in a companion paper of decision feedback for a baseband channel, we derive the form of the optimum receiver filters via a matrix Wiener-Hopf analysis. We obtain explicit analytical expressions for minimum mean-square error and optimum transmitting filters. The optimization is subject to a constraint on the transmitted signal power and assumes no prior decision errors. The class of QAM transmitter and receiver structures treated here is actually much larger than the class usually considered for QAM systems. However, our results for decision feedback equalization show that, for nonexcess bandwidth systems, optimum performance is achievable without taking advantage of the most general structure. If the transmitter is required to have the conventional QAM structure, study of the time continuous system that gives rise to the sampled data system considered here demonstrates that under quite general assumptions a nonexcess bandwidth system is optimum. Finally, the explicit description of the optimum transmitting matrix filter follows from an information-theoretic “water-pouring” algorithm in conjunction with the determination of the form of the points of maxima of a determinant extremal problem.
{"title":"Theory of minimum mean-square-error QAM systems employing decision feedback equalization","authors":"D. Falconer, G. Foschini","doi":"10.1002/J.1538-7305.1973.TB02710.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB02710.X","url":null,"abstract":"Decision feedback equalization is presently of interest as a technique for reducing intersymbol interference in high-rate PAM data communications systems. The basic principle is to cancel out intersymbol interference arising from previously decided data symbols at the receiver, leaving remaining intersymbol interference components to be handled by linear equalization. In this work we consider the application of decision feedback equalization to quadrature-amplitude modulation (QAM) transmission, in which two independent information streams modulate quadrature carriers. Extending Salz's treatment in a companion paper of decision feedback for a baseband channel, we derive the form of the optimum receiver filters via a matrix Wiener-Hopf analysis. We obtain explicit analytical expressions for minimum mean-square error and optimum transmitting filters. The optimization is subject to a constraint on the transmitted signal power and assumes no prior decision errors. The class of QAM transmitter and receiver structures treated here is actually much larger than the class usually considered for QAM systems. However, our results for decision feedback equalization show that, for nonexcess bandwidth systems, optimum performance is achievable without taking advantage of the most general structure. If the transmitter is required to have the conventional QAM structure, study of the time continuous system that gives rise to the sampled data system considered here demonstrates that under quite general assumptions a nonexcess bandwidth system is optimum. Finally, the explicit description of the optimum transmitting matrix filter follows from an information-theoretic “water-pouring” algorithm in conjunction with the determination of the form of the points of maxima of a determinant extremal problem.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"2 1","pages":"1821-1849"},"PeriodicalIF":0.0,"publicationDate":"1973-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83795796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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