Pub Date : 1994-10-02DOI: 10.1109/MILCOM.1994.473858
Peter A. J. Nagy
This paper presents a modulation classifier that is designed to handle multi-channel systems and situations where several digitally modulated signals are mixed. This is accomplished by dividing the analyzed signal into individual components. The signal components are located via a smoothed amplitude spectrum and individually classified by a single tone classifier that can handle CW, ASK, BPSK, and QPSK signals. FSK signals can also be handled since they are divided into two peaks, which are separately classified. Each peak in an FSK signal will be an ASK signal. The FSK signal is thus classified as two ASK signals, and by analyzing their correlation it can be established that they form an FSK signal.<>
{"title":"A modulation classifier for multi-channel systems and multi-transmitter situations","authors":"Peter A. J. Nagy","doi":"10.1109/MILCOM.1994.473858","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473858","url":null,"abstract":"This paper presents a modulation classifier that is designed to handle multi-channel systems and situations where several digitally modulated signals are mixed. This is accomplished by dividing the analyzed signal into individual components. The signal components are located via a smoothed amplitude spectrum and individually classified by a single tone classifier that can handle CW, ASK, BPSK, and QPSK signals. FSK signals can also be handled since they are divided into two peaks, which are separately classified. Each peak in an FSK signal will be an ASK signal. The FSK signal is thus classified as two ASK signals, and by analyzing their correlation it can be established that they form an FSK signal.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125984996","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473987
J. Cleveland
The model of the digitized battlefield utilizes communications networks that automatically execute data transfers between functional areas-combat, combat support and combat service support. With evolving technology and standards, high frequency (HF) radio networking offers one avenue to support tactical and global communications requirements for quick responses to sudden contingencies and for rapid deployments. Standardized ALE procedures, improved signal-processing modems, and interoperable message transfer protocols provide basic elements to create adaptive, automated HF radio networks to support information exchange among Command, Control, Communications and Intelligence (C4I) systems. Unlike other communications services, however, dynamic ionospheric conditions, heavy utilization and inadvertent jamming make the HF channel a hostile one, where links between nodes are subject to frequent failure. These factors yield significantly degraded performance without adaptive, dynamic management. The occurrence of self-jamming under heavy load conditions adds further complexity to performance analysis and prediction. Assessment of network design relative to optimized performance presents a challenging problem. This paper describes computer simulation predictions which provide a basis for assessment of HF radio networks that operates with the MIL-STD procedures and protocols. The simulation model extends earlier work for MIL-STD-188-141A Automatic Link Establishment (ALE) with an implementation of MIL-STD-187-721 for HF network access. It also implements the message format provisions of MIL-STD-188-220 for the data link protocol to enhance battlefield interoperability and compatibility to support the exchange of digital information. It adds to simulation efforts on HF radio network performance. The purpose of this study is to assess the integration of these MIL-STD protocols and the network performance under heavy message load. The results are applied to network management under normal as well as stressed conditions to optimize information exchange and network resource allocation.<>
{"title":"Simulation of digital message transfer with MIL-STD protocols across HF radio networks","authors":"J. Cleveland","doi":"10.1109/MILCOM.1994.473987","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473987","url":null,"abstract":"The model of the digitized battlefield utilizes communications networks that automatically execute data transfers between functional areas-combat, combat support and combat service support. With evolving technology and standards, high frequency (HF) radio networking offers one avenue to support tactical and global communications requirements for quick responses to sudden contingencies and for rapid deployments. Standardized ALE procedures, improved signal-processing modems, and interoperable message transfer protocols provide basic elements to create adaptive, automated HF radio networks to support information exchange among Command, Control, Communications and Intelligence (C4I) systems. Unlike other communications services, however, dynamic ionospheric conditions, heavy utilization and inadvertent jamming make the HF channel a hostile one, where links between nodes are subject to frequent failure. These factors yield significantly degraded performance without adaptive, dynamic management. The occurrence of self-jamming under heavy load conditions adds further complexity to performance analysis and prediction. Assessment of network design relative to optimized performance presents a challenging problem. This paper describes computer simulation predictions which provide a basis for assessment of HF radio networks that operates with the MIL-STD procedures and protocols. The simulation model extends earlier work for MIL-STD-188-141A Automatic Link Establishment (ALE) with an implementation of MIL-STD-187-721 for HF network access. It also implements the message format provisions of MIL-STD-188-220 for the data link protocol to enhance battlefield interoperability and compatibility to support the exchange of digital information. It adds to simulation efforts on HF radio network performance. The purpose of this study is to assess the integration of these MIL-STD protocols and the network performance under heavy message load. The results are applied to network management under normal as well as stressed conditions to optimize information exchange and network resource allocation.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125218197","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473822
S. V. Schell, D.L. Smith
Recent progress by several groups around the world shows that moving average linear time-invariant channels that distort digital communication signals can be identified using only second-order statistics, provided that certain conditions on the channel and data are met. In this paper, a subchannel response matching channel identification method is modified to exploit prior knowledge of the pulse-shaping filter. Computer simulations demonstrate the method's performance as a channel estimator and as an equalizer compared to appropriate lower bounds on the normalized channel estimation error and the bit error rate.<>
{"title":"Improved performance of blind equalization using prior knowledge of transmitter filter","authors":"S. V. Schell, D.L. Smith","doi":"10.1109/MILCOM.1994.473822","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473822","url":null,"abstract":"Recent progress by several groups around the world shows that moving average linear time-invariant channels that distort digital communication signals can be identified using only second-order statistics, provided that certain conditions on the channel and data are met. In this paper, a subchannel response matching channel identification method is modified to exploit prior knowledge of the pulse-shaping filter. Computer simulations demonstrate the method's performance as a channel estimator and as an equalizer compared to appropriate lower bounds on the normalized channel estimation error and the bit error rate.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127874537","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473836
S. Drakul, E. Biglieri
This paper describes a method for selecting pulse shapes for digital transmission over band- and power-limited channels. These signals are easily generated and lend themselves to a sampling receiver with limited complexity. In particular, we show how to generate an 8-dimensional signal basis that allows one to achieve a bit-error rate of 10/sup -5/ at E/sub b//N/sub 0/=3.6 dB with a spectral efficiency 1.7 bits/s/Hz.<>
{"title":"A method for selecting pulse shapes in digital transmission","authors":"S. Drakul, E. Biglieri","doi":"10.1109/MILCOM.1994.473836","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473836","url":null,"abstract":"This paper describes a method for selecting pulse shapes for digital transmission over band- and power-limited channels. These signals are easily generated and lend themselves to a sampling receiver with limited complexity. In particular, we show how to generate an 8-dimensional signal basis that allows one to achieve a bit-error rate of 10/sup -5/ at E/sub b//N/sub 0/=3.6 dB with a spectral efficiency 1.7 bits/s/Hz.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128780445","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473996
R. R. Henry, J. Evanowsky
Modern and future military equipment and tactics require the use of wideband links to exchange bandwidth-intensive information such as video and images. However, current and proposed wideband networks such as ATM have been designed for peacetime, i.e. well-behaved operation. The research described herein develops an original fast ATM routing (FAR) protocol which adapts wideband ATM networks for operation in the dynamic global grid environment. It is shown that this FAR protocol provides robust performance in such an environment.<>
{"title":"A fast ATM routing algorithm for the dynamic global grid environment","authors":"R. R. Henry, J. Evanowsky","doi":"10.1109/MILCOM.1994.473996","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473996","url":null,"abstract":"Modern and future military equipment and tactics require the use of wideband links to exchange bandwidth-intensive information such as video and images. However, current and proposed wideband networks such as ATM have been designed for peacetime, i.e. well-behaved operation. The research described herein develops an original fast ATM routing (FAR) protocol which adapts wideband ATM networks for operation in the dynamic global grid environment. It is shown that this FAR protocol provides robust performance in such an environment.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116659508","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473968
Z. Zvonar, D. Brady
We investigate the performance of low-complexity decorrelating multiuser receivers with diversity reception in frequency-nonselective Rayleigh fading asynchronous CDMA channels. The impact of fading dynamics on the differentially coherent receiver with equal-gain combining is quantified. We also analyze an adaptive coherent multiuser receiver utilizing decision-directed carrier recovery and maximal ratio combining, and bound its error probability showing the impact of imperfect channel estimates and multiple-access interference. Both multiuser receivers have superior performance compared to their conventional counterparts. The comparison of two receiver structures indicates that the coherent decorrelating detector with diversity reception is preferable in nonselective fading CDMA channels with memory.<>
{"title":"Adaptive multiuser receivers with diversity reception for nonselective Rayleigh fading asynchronous CDMA channels","authors":"Z. Zvonar, D. Brady","doi":"10.1109/MILCOM.1994.473968","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473968","url":null,"abstract":"We investigate the performance of low-complexity decorrelating multiuser receivers with diversity reception in frequency-nonselective Rayleigh fading asynchronous CDMA channels. The impact of fading dynamics on the differentially coherent receiver with equal-gain combining is quantified. We also analyze an adaptive coherent multiuser receiver utilizing decision-directed carrier recovery and maximal ratio combining, and bound its error probability showing the impact of imperfect channel estimates and multiple-access interference. Both multiuser receivers have superior performance compared to their conventional counterparts. The comparison of two receiver structures indicates that the coherent decorrelating detector with diversity reception is preferable in nonselective fading CDMA channels with memory.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131567534","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473861
G. Orr, B. Rice
Estimations of the probabilities of bit errors in a fast-hopped M-ary-frequency-shift-keyed (MFSK) signal can be obtained by specifying a range of "scenarios" and an exhaustive set of "subscenarios" for which the occurrence or non-occurrence of symbol errors can be determined. The probability of symbol error for a given scenario is computed as the sum of the probabilities of occurrence of those subscenarios that produce symbol errors. An error is assumed to occur when the channel output of a most-often-jammed channel exceeds that of the channel containing the signal. An efficient method is presented for computing the probabilities of each possible subscenario. In the important case that there is only one jamming tone in the frequency band of a jammed hop, a partitioning technique enables precise calculations of these probabilities even when the number of hops combined is quite large. Monte Carlo techniques plus precise calculations in special cases are used to calculate the probabilities when the number of jamming tones per jammed hop is greater than one.<>
{"title":"Effect of multitone jammers on error rates of fast-hopped MFSK signals with no side information","authors":"G. Orr, B. Rice","doi":"10.1109/MILCOM.1994.473861","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473861","url":null,"abstract":"Estimations of the probabilities of bit errors in a fast-hopped M-ary-frequency-shift-keyed (MFSK) signal can be obtained by specifying a range of \"scenarios\" and an exhaustive set of \"subscenarios\" for which the occurrence or non-occurrence of symbol errors can be determined. The probability of symbol error for a given scenario is computed as the sum of the probabilities of occurrence of those subscenarios that produce symbol errors. An error is assumed to occur when the channel output of a most-often-jammed channel exceeds that of the channel containing the signal. An efficient method is presented for computing the probabilities of each possible subscenario. In the important case that there is only one jamming tone in the frequency band of a jammed hop, a partitioning technique enables precise calculations of these probabilities even when the number of hops combined is quite large. Monte Carlo techniques plus precise calculations in special cases are used to calculate the probabilities when the number of jamming tones per jammed hop is greater than one.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128159521","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473846
P.A. Tirkas, J. Peng, C. Balanis, G. Barber
Electromagnetic interference and interaction with complex helicopter structures is examined using general purpose electromagnetic codes such as the numerical electromagnetics code (NEC), surface patch (ESP) code and a finite-difference time-domain (FDTD) code. The geometry of a generic NASA helicopter model (7:1 scale) is processed using the GEOM which is a general geometry preprocessing code that was developed at Arizona State University. Initially, the interference effect of using two wire antennas on the helicopter is analyzed by examining their effect on the far-field radiation pattern, using the NEC and ESP. Then the FDTD is applied for the simulation of plane wave penetration into the helicopter fuselage which was assumed partially conducting/partially composite.<>
{"title":"Electromagnetic interference and interaction with complex helicopter structures","authors":"P.A. Tirkas, J. Peng, C. Balanis, G. Barber","doi":"10.1109/MILCOM.1994.473846","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473846","url":null,"abstract":"Electromagnetic interference and interaction with complex helicopter structures is examined using general purpose electromagnetic codes such as the numerical electromagnetics code (NEC), surface patch (ESP) code and a finite-difference time-domain (FDTD) code. The geometry of a generic NASA helicopter model (7:1 scale) is processed using the GEOM which is a general geometry preprocessing code that was developed at Arizona State University. Initially, the interference effect of using two wire antennas on the helicopter is analyzed by examining their effect on the far-field radiation pattern, using the NEC and ESP. Then the FDTD is applied for the simulation of plane wave penetration into the helicopter fuselage which was assumed partially conducting/partially composite.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134246889","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473837
C. Long, K. Chugg, A. Polydoros
Maximum likelihood decision theory is applied to the problem of classification of quadrature-modulated digital communication signals. Several aspects of the existing low signal-to-noise ratio (SNR) results are extended to the moderate and high SNR environments. An approximate probability density function (PDF) for the single-term approximation to the average log-likelihood-ratio (ALLR) which is valid at all SNR values is presented and its superior accuracy, compared to the low SNR pdf, is verified via computer simulation. Computer simulation is also used to show that multiple-term approximations to the ALLR may provide significant performance gains relative to their individual terms. A simple, practical method for setting the threshold of the ALLR test is presented and it is shown, through simulation, that little performance degradation is suffered relative to the optimal setting, which is difficult to determine analytically in most cases. True signal pre-processing techniques are also presented, and it is demonstrated that their use significantly improves the robustness of the classification algorithms for phase-shift-keying signals in frequency-uncertain environments.<>
{"title":"Further results in likelihood classification of QAM signals","authors":"C. Long, K. Chugg, A. Polydoros","doi":"10.1109/MILCOM.1994.473837","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473837","url":null,"abstract":"Maximum likelihood decision theory is applied to the problem of classification of quadrature-modulated digital communication signals. Several aspects of the existing low signal-to-noise ratio (SNR) results are extended to the moderate and high SNR environments. An approximate probability density function (PDF) for the single-term approximation to the average log-likelihood-ratio (ALLR) which is valid at all SNR values is presented and its superior accuracy, compared to the low SNR pdf, is verified via computer simulation. Computer simulation is also used to show that multiple-term approximations to the ALLR may provide significant performance gains relative to their individual terms. A simple, practical method for setting the threshold of the ALLR test is presented and it is shown, through simulation, that little performance degradation is suffered relative to the optimal setting, which is difficult to determine analytically in most cases. True signal pre-processing techniques are also presented, and it is demonstrated that their use significantly improves the robustness of the classification algorithms for phase-shift-keying signals in frequency-uncertain environments.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134348907","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 : 1994-10-02DOI: 10.1109/MILCOM.1994.473832
Chih-Yuan Chang, A. Paulraj, T. Kailath
We study the performance of an ATM switch which clusters a set of broadband packet channels as a transmission group. The exact analysis for the performance of systems employing this concept includes solving for the roots of equations involving transcendental functions and can only be carried out numerically. Thus, its performance has mainly been understood by the use of simulation. We derive a close-form approximation for the performance of multichannel switches under independent uniform input traffic. Our approximation differs from simulation results by at most 8 percent for channel group sizes r=2,...,32 and is exact in the case where the channel group size is unity.<>
{"title":"A close-form performance approximation for nonblocking ATM switches with channel grouping","authors":"Chih-Yuan Chang, A. Paulraj, T. Kailath","doi":"10.1109/MILCOM.1994.473832","DOIUrl":"https://doi.org/10.1109/MILCOM.1994.473832","url":null,"abstract":"We study the performance of an ATM switch which clusters a set of broadband packet channels as a transmission group. The exact analysis for the performance of systems employing this concept includes solving for the roots of equations involving transcendental functions and can only be carried out numerically. Thus, its performance has mainly been understood by the use of simulation. We derive a close-form approximation for the performance of multichannel switches under independent uniform input traffic. Our approximation differs from simulation results by at most 8 percent for channel group sizes r=2,...,32 and is exact in the case where the channel group size is unity.<<ETX>>","PeriodicalId":337873,"journal":{"name":"Proceedings of MILCOM '94","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132346084","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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