The asymmetric digital subscriber line service attempts to provide 1.6 Mb/s data transmission over a single twisted-pair copper loop for distances up to 18000 ft. The authors investigate the various system components necessary to realize such a system on a single integrated circuit. They discuss the modulation format, adaptive equalization and its convergence, and system sensitivity to sampling phase error. A comparison of conventional quadrature amplitude modulation (QAM) and pulse amplitude modulation (PAM) schemes is presented. It is concluded that a QAM-based system can meet the system objectives. The use of fractionally spaced equalization and error prediction as means of improving SNR and reducing the hardware complexity is investigated for such a system. It is shown that with 6 T/2-spaced feedforward equalizer taps, eight decision-feedback equalizer taps, and two error predictor taps, the proposed digital QAM system can achieve performance close to that of an ideal infinite-length equalizer.<>
{"title":"Performance analysis of a QAM adaptive receiver for 1.6 Mbps digital subscriber line transmission","authors":"B. Daneshrad, H. Samueli","doi":"10.1109/ICC.1992.268074","DOIUrl":"https://doi.org/10.1109/ICC.1992.268074","url":null,"abstract":"The asymmetric digital subscriber line service attempts to provide 1.6 Mb/s data transmission over a single twisted-pair copper loop for distances up to 18000 ft. The authors investigate the various system components necessary to realize such a system on a single integrated circuit. They discuss the modulation format, adaptive equalization and its convergence, and system sensitivity to sampling phase error. A comparison of conventional quadrature amplitude modulation (QAM) and pulse amplitude modulation (PAM) schemes is presented. It is concluded that a QAM-based system can meet the system objectives. The use of fractionally spaced equalization and error prediction as means of improving SNR and reducing the hardware complexity is investigated for such a system. It is shown that with 6 T/2-spaced feedforward equalizer taps, eight decision-feedback equalizer taps, and two error predictor taps, the proposed digital QAM system can achieve performance close to that of an ideal infinite-length equalizer.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125278332","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}
A media space is currently being constructed which consists of three distinct components: audio/video equipment; groupware presenting a shared workspace; and a distributed software architecture providing layered services to support a variety of modes of cooperation in a highly-interactive work environment. The hardware configuration is described, with comments on the significance of equipment layout and performance, based on previous experience in multimedia conferencing. Initial work on a distributed software architecture is discussed, which will provide appropriate audio/video services layered to support a variety of modes of interaction.<>
{"title":"A multimedia system for flexible cooperation","authors":"S. Wilbur, B. Hewitt, S. Ing","doi":"10.1109/ICC.1992.268147","DOIUrl":"https://doi.org/10.1109/ICC.1992.268147","url":null,"abstract":"A media space is currently being constructed which consists of three distinct components: audio/video equipment; groupware presenting a shared workspace; and a distributed software architecture providing layered services to support a variety of modes of cooperation in a highly-interactive work environment. The hardware configuration is described, with comments on the significance of equipment layout and performance, based on previous experience in multimedia conferencing. Initial work on a distributed software architecture is discussed, which will provide appropriate audio/video services layered to support a variety of modes of interaction.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125315392","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}
A new adaptive source coding technique called edge modified vector quantization (EMVQ) is introduced. By using EMVQ, an image is encoded in two stages: coarse image coding and edge modification. The redundancies in the smooth area are further reduced by applying large block segmentation, hierarchical VQ and finite state prediction. Sharp edges are well preserved by compensation of their encoding quantization error. A high compression ratio was achieved and the reconstructed images still had satisfactory perceptual quality. The EMVQ coding results are demonstrated.<>
{"title":"Edge modified vector quantization for image compression","authors":"P. Yu, A. Venetsanopoulos","doi":"10.1109/ICC.1992.268224","DOIUrl":"https://doi.org/10.1109/ICC.1992.268224","url":null,"abstract":"A new adaptive source coding technique called edge modified vector quantization (EMVQ) is introduced. By using EMVQ, an image is encoded in two stages: coarse image coding and edge modification. The redundancies in the smooth area are further reduced by applying large block segmentation, hierarchical VQ and finite state prediction. Sharp edges are well preserved by compensation of their encoding quantization error. A high compression ratio was achieved and the reconstructed images still had satisfactory perceptual quality. The EMVQ coding results are demonstrated.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125227148","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}
A novel design for a phase-locked loop (PLL) frequency synthesizer is proposed to obtain a fast acquisition time. For conventional PLL frequency synthesizer design, the smallest frequency increment is the same as the reference frequency. Thus, a low reference frequency can only be used at the expense of a longer acquisition time. However, in the proposed PLL synthesizer, by introducing n-stage novel type cycle swallowers, the smallest frequency increment and the reference frequency can be made to be independent of each other. Therefore, by using higher feedback and reference frequencies, the proposed synthesizer can attain an acquisition performance over 10/sup 3/ times faster than that of the conventional PLL synthesizer and maintain the same smallest frequency increment for the output frequency. The performance of the design is illustrated by experimental results.<>
{"title":"Fast acquisition frequency synthesizer with n-stage novel type cycle swallowers","authors":"D. Park, Shinsaku Mori","doi":"10.1109/ICC.1992.268081","DOIUrl":"https://doi.org/10.1109/ICC.1992.268081","url":null,"abstract":"A novel design for a phase-locked loop (PLL) frequency synthesizer is proposed to obtain a fast acquisition time. For conventional PLL frequency synthesizer design, the smallest frequency increment is the same as the reference frequency. Thus, a low reference frequency can only be used at the expense of a longer acquisition time. However, in the proposed PLL synthesizer, by introducing n-stage novel type cycle swallowers, the smallest frequency increment and the reference frequency can be made to be independent of each other. Therefore, by using higher feedback and reference frequencies, the proposed synthesizer can attain an acquisition performance over 10/sup 3/ times faster than that of the conventional PLL synthesizer and maintain the same smallest frequency increment for the output frequency. The performance of the design is illustrated by experimental results.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"212 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122646337","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}
The author focuses on Tellabs' approach to quality and meeting/exceeding the customers' total requirements. Tellabs has established and implemented a quality philosophy that emphasizes continuous process improvement, strategic quality management, and senior management commitment. Through this quality philosophy and associated programs total customer satisfaction can be achieved.<>
{"title":"Total customer satisfaction (telecommunication products)","authors":"J. Kohler","doi":"10.1109/ICC.1992.268137","DOIUrl":"https://doi.org/10.1109/ICC.1992.268137","url":null,"abstract":"The author focuses on Tellabs' approach to quality and meeting/exceeding the customers' total requirements. Tellabs has established and implemented a quality philosophy that emphasizes continuous process improvement, strategic quality management, and senior management commitment. Through this quality philosophy and associated programs total customer satisfaction can be achieved.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131476149","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}
A direct-sequence spread-spectrum receiver using M-ary phase shift keyed signaling is presented with digital algorithms for coherent data demodulation, diversity combining, and frequency offset estimation. These algorithms are derived by applying the maximum-likelihood rule. A RAKE-structure is used to resolve the time diversity due to multipath propagation of the frequency-selective fading channel. Such conditions are typically encountered in microcellular communication systems like personal communications networks, or wireless local area networks (LANs). The robust transient behavior of the present receiver with an automatic frequency control scheme, based on the non-biased frequency estimator, and the fairly low numerical complexity make these algorithms well suited for digital implementation.<>
{"title":"A coherent spread-spectrum RAKE-receiver with maximum-likelihood frequency estimation","authors":"U. Fawer","doi":"10.1109/ICC.1992.268086","DOIUrl":"https://doi.org/10.1109/ICC.1992.268086","url":null,"abstract":"A direct-sequence spread-spectrum receiver using M-ary phase shift keyed signaling is presented with digital algorithms for coherent data demodulation, diversity combining, and frequency offset estimation. These algorithms are derived by applying the maximum-likelihood rule. A RAKE-structure is used to resolve the time diversity due to multipath propagation of the frequency-selective fading channel. Such conditions are typically encountered in microcellular communication systems like personal communications networks, or wireless local area networks (LANs). The robust transient behavior of the present receiver with an automatic frequency control scheme, based on the non-biased frequency estimator, and the fairly low numerical complexity make these algorithms well suited for digital implementation.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"15 12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127669104","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}
The author establishes that a false pseudo-noise (PN) code lock can happen with high probability for very strong signals if a Gold sequence is employed for the PN-spreading. The autocorrelation of a Gold sequence has off-peaks. The off-peaks may cause the final PN-code lock decision variable to exceed the preset threshold value when the received power is high, and yield false PN-code lock decisions. For example, the off-peaks can cause false PN-code lock when the received power exceeds -118 dBm and -103 dBm for 3 kb/s and 72 kb/s data rates, respectively. Thus, the received power should be below these numbers to avoid the false PN code lock. For a single-access system, it is recommended that the channel employ one of the two maximal-length sequences in a Gold sequence family and thus remove the off-peaks in a PN sequence autocorrelation.<>
{"title":"False PN-code lock due to off-peaks of Gold sequence autocorrelation (satellite transponders)","authors":"H. M. Kwon","doi":"10.1109/ICC.1992.268229","DOIUrl":"https://doi.org/10.1109/ICC.1992.268229","url":null,"abstract":"The author establishes that a false pseudo-noise (PN) code lock can happen with high probability for very strong signals if a Gold sequence is employed for the PN-spreading. The autocorrelation of a Gold sequence has off-peaks. The off-peaks may cause the final PN-code lock decision variable to exceed the preset threshold value when the received power is high, and yield false PN-code lock decisions. For example, the off-peaks can cause false PN-code lock when the received power exceeds -118 dBm and -103 dBm for 3 kb/s and 72 kb/s data rates, respectively. Thus, the received power should be below these numbers to avoid the false PN code lock. For a single-access system, it is recommended that the channel employ one of the two maximal-length sequences in a Gold sequence family and thus remove the off-peaks in a PN sequence autocorrelation.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127724214","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}
The authors study the error performance of uncoded quadrature phase shift keyed (QPSK) signals transmitted over a two-ray frequency selective Rayleigh fading channel. A Viterbi receiver with perfect channel state information is assumed. For a rectangular baseband pulse, it was found that the relative delay between the two arrival rays introduces a diversity effect which helps to improve the error performance over that of a one-ray, frequency non-selective fading channel.<>
{"title":"Bit-error probability of uncoded QPSK transmitted over a 2-ray frequency selective Rayleigh fading channel","authors":"T. Chan, P. Ho","doi":"10.1109/ICC.1992.268242","DOIUrl":"https://doi.org/10.1109/ICC.1992.268242","url":null,"abstract":"The authors study the error performance of uncoded quadrature phase shift keyed (QPSK) signals transmitted over a two-ray frequency selective Rayleigh fading channel. A Viterbi receiver with perfect channel state information is assumed. For a rectangular baseband pulse, it was found that the relative delay between the two arrival rays introduces a diversity effect which helps to improve the error performance over that of a one-ray, frequency non-selective fading channel.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127763906","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}
K. Ramchandran, Antonio Ortega, K. Uz, M. Vetterli
In the context of digital terrestrial broadcast of high-definition television (HDTV), the use of multiresolution joint source-channel coding is shown to provide an attractive alternative to traditional single resolution (SR) digital techniques. While SR schemes suffer from a sharp threshold effect in the fringes of the broadcast area, it is shown that a matched multiresolution approach to both source and channel coding can provide a stepwise graceful degradation. Furthermore, this multiresolution approach improves the behavior, in terms of coverage and robustness of the transmission scheme, over systems that are not specifically designed to broadcast situations. The authors examine the alternatives available for multiresolution transmission, through embedded modulation, possibly trellis-coded to increase coverage range. From a systems point of view, they also discuss the tradeoffs involved in the choice of coverage areas for the low- and high-resolution signals.<>
{"title":"Multiresolution broadcast for digital HDTV using joint source-channel coding","authors":"K. Ramchandran, Antonio Ortega, K. Uz, M. Vetterli","doi":"10.1109/ICC.1992.268220","DOIUrl":"https://doi.org/10.1109/ICC.1992.268220","url":null,"abstract":"In the context of digital terrestrial broadcast of high-definition television (HDTV), the use of multiresolution joint source-channel coding is shown to provide an attractive alternative to traditional single resolution (SR) digital techniques. While SR schemes suffer from a sharp threshold effect in the fringes of the broadcast area, it is shown that a matched multiresolution approach to both source and channel coding can provide a stepwise graceful degradation. Furthermore, this multiresolution approach improves the behavior, in terms of coverage and robustness of the transmission scheme, over systems that are not specifically designed to broadcast situations. The authors examine the alternatives available for multiresolution transmission, through embedded modulation, possibly trellis-coded to increase coverage range. From a systems point of view, they also discuss the tradeoffs involved in the choice of coverage areas for the low- and high-resolution signals.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132578371","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}
Equalization structures for maximum likelihood (ML) reception of data transmitted over intersymbol interference channels are studied. The equalizer that is best for the ML receiver is derived from a general theory of decision-aided equalization. The resulting optimum equalizers are linear and do not use previous decisions. If the equalizer complexity is permitted to be infinite, then a general optimum class of structures is derived that includes the decision feedback equalizer and the lesser-known autoregressive moving average filters. When a complexity constraint is also imposed on the equalizer, one of the structures in this class will be best for a given ML receiver. The best structure is found by a simple search procedure, which is given. The results indicate that near-optimum performance can be achieved by using this approach at a great computational reduction.<>
{"title":"A cost-effective maximum likelihood receiver for multicarrier systems","authors":"J. S. Chow, J. Cioffi","doi":"10.1109/ICC.1992.268072","DOIUrl":"https://doi.org/10.1109/ICC.1992.268072","url":null,"abstract":"Equalization structures for maximum likelihood (ML) reception of data transmitted over intersymbol interference channels are studied. The equalizer that is best for the ML receiver is derived from a general theory of decision-aided equalization. The resulting optimum equalizers are linear and do not use previous decisions. If the equalizer complexity is permitted to be infinite, then a general optimum class of structures is derived that includes the decision feedback equalizer and the lesser-known autoregressive moving average filters. When a complexity constraint is also imposed on the equalizer, one of the structures in this class will be best for a given ML receiver. The best structure is found by a simple search procedure, which is given. The results indicate that near-optimum performance can be achieved by using this approach at a great computational reduction.<<ETX>>","PeriodicalId":170618,"journal":{"name":"[Conference Record] SUPERCOMM/ICC '92 Discovering a New World of Communications","volume":"244 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132621252","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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