Pub Date : 1997-11-02DOI: 10.1109/ACSSC.1997.680559
A. Weiss, B. Friedlander
Synchronous code-division multiple-access (CDMA) techniques possess intrinsic protection against co-channel interference due to the orthogonal spreading codes used. However, in the presence of multipath the signals lose their orthogonality properly leading to increased cross correlation. In these cases channel estimation may be needed in order to improve the detection of the desired symbols. We propose and compare several algorithms for channel estimation of a synchronous CDMA point to multipoint link (downlink) which uses aperiodic spreading waveforms. We compare by simulation and analysis a subspace approach, a pilot-aided approach, and a decision feedback approach.
{"title":"CDMA downlink channel estimation with aperiodic spreading","authors":"A. Weiss, B. Friedlander","doi":"10.1109/ACSSC.1997.680559","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680559","url":null,"abstract":"Synchronous code-division multiple-access (CDMA) techniques possess intrinsic protection against co-channel interference due to the orthogonal spreading codes used. However, in the presence of multipath the signals lose their orthogonality properly leading to increased cross correlation. In these cases channel estimation may be needed in order to improve the detection of the desired symbols. We propose and compare several algorithms for channel estimation of a synchronous CDMA point to multipoint link (downlink) which uses aperiodic spreading waveforms. We compare by simulation and analysis a subspace approach, a pilot-aided approach, and a decision feedback approach.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117049870","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.679108
S. Oraintara, T.Q. Nguyen
General concept of multidimensional (M-D) two-channel perfect reconstruction (PR) filter banks is presented. The framework starts by constructing a factorizable halfband function in M-D and, subsequently, uses spectral factorization to obtain the subband filters. The number of zeros at the aliasing frequency can be obtained easily by using variable transformation from 1-D to M-D. The possible passband shape is discussed. A novel condition for 2-channel PR filter banks in M-D is presented by which the choices of possible passband shapes are significantly reduced. Finally, a frequency mapping between two possible passbands is proposed. A necessary and sufficient condition for the mapping to preserve the PR condition is presented.
{"title":"Multidimensional 2-channel PR filter banks","authors":"S. Oraintara, T.Q. Nguyen","doi":"10.1109/ACSSC.1997.679108","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679108","url":null,"abstract":"General concept of multidimensional (M-D) two-channel perfect reconstruction (PR) filter banks is presented. The framework starts by constructing a factorizable halfband function in M-D and, subsequently, uses spectral factorization to obtain the subband filters. The number of zeros at the aliasing frequency can be obtained easily by using variable transformation from 1-D to M-D. The possible passband shape is discussed. A novel condition for 2-channel PR filter banks in M-D is presented by which the choices of possible passband shapes are significantly reduced. Finally, a frequency mapping between two possible passbands is proposed. A necessary and sufficient condition for the mapping to preserve the PR condition is presented.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116283786","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.680049
T. Eyceoz, A. Duel-Hallen, H. Hallen
We investigated a new deterministic approach to the estimation and prediction of the fading channel by exploiting the physical nature of the flat fading signal. Since the direct signal and the reflected signals form an interference pattern, the received signal is given by a sum of several scattered components. These are distinguished by their Doppler shifts at the mobile. The slowly varying parameters associated with these components are determined and tracked, and the composite fading signal is predicted. This approach will potentially result in the ability to anticipate and avoid "deep fades" which severely limit the performance of wireless communications systems and will aid in the development of low power mobile radio systems.
{"title":"Prediction of fast fading parameters by resolving the interference pattern","authors":"T. Eyceoz, A. Duel-Hallen, H. Hallen","doi":"10.1109/ACSSC.1997.680049","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680049","url":null,"abstract":"We investigated a new deterministic approach to the estimation and prediction of the fading channel by exploiting the physical nature of the flat fading signal. Since the direct signal and the reflected signals form an interference pattern, the received signal is given by a sum of several scattered components. These are distinguished by their Doppler shifts at the mobile. The slowly varying parameters associated with these components are determined and tracked, and the composite fading signal is predicted. This approach will potentially result in the ability to anticipate and avoid \"deep fades\" which severely limit the performance of wireless communications systems and will aid in the development of low power mobile radio systems.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"262 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116485046","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.679200
R. Kouassi, J. Devaux, Pierre Gouton, Michel Paindavoine
The current systems of image capture are based on red, green and blue (R,G,B) principles. But, this model of capturing color images is different from the human visual system. So, to obtain a representation which approaches the human system, one uses the intensity and chrominance space. As this representation is non-linear, it introduces color instability. Thus, to analyze natural color images, we use the Karhunen-Loeve space, which allows a large decorrelation of the color components, a high definition of colors and an increased compression ratio for very homogeneous images.
{"title":"Application of the Karhunen-Loeve transform for natural color images analysis","authors":"R. Kouassi, J. Devaux, Pierre Gouton, Michel Paindavoine","doi":"10.1109/ACSSC.1997.679200","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679200","url":null,"abstract":"The current systems of image capture are based on red, green and blue (R,G,B) principles. But, this model of capturing color images is different from the human visual system. So, to obtain a representation which approaches the human system, one uses the intensity and chrominance space. As this representation is non-linear, it introduces color instability. Thus, to analyze natural color images, we use the Karhunen-Loeve space, which allows a large decorrelation of the color components, a high definition of colors and an increased compression ratio for very homogeneous images.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"225 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115319141","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.679095
G. Benitz
High-definition vector imaging (HDVI) is a data-adaptive approach to synthetic aperture radar (SAR) image reconstruction based on superresolution techniques originally developed for passive sensor arrays. The goal is to produce more informative, higher resolution imagery for improving target recognition with UHF and millimeter-wave SAR. Algorithms presented here include 2-D minimum-variance techniques based on the MLM (Capon) algorithm and a 2-D version of the MUSIC algorithm. A comparison of techniques via simulation is provided. Results are presented for wideband rail SAR measurements of reflectors in foliage, demonstrating resolution improvement and clutter rejection. Also, results of processing data from an airborne millimeter-wave SAR demonstrate improved resolution and speckle reduction. The "Vector" aspect, i.e., the incorporation of non-pointlike scattering models to enable characterization of scattering mechanisms, is briefly discussed.
{"title":"High-definition vector imaging for synthetic aperture radar","authors":"G. Benitz","doi":"10.1109/ACSSC.1997.679095","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679095","url":null,"abstract":"High-definition vector imaging (HDVI) is a data-adaptive approach to synthetic aperture radar (SAR) image reconstruction based on superresolution techniques originally developed for passive sensor arrays. The goal is to produce more informative, higher resolution imagery for improving target recognition with UHF and millimeter-wave SAR. Algorithms presented here include 2-D minimum-variance techniques based on the MLM (Capon) algorithm and a 2-D version of the MUSIC algorithm. A comparison of techniques via simulation is provided. Results are presented for wideband rail SAR measurements of reflectors in foliage, demonstrating resolution improvement and clutter rejection. Also, results of processing data from an airborne millimeter-wave SAR demonstrate improved resolution and speckle reduction. The \"Vector\" aspect, i.e., the incorporation of non-pointlike scattering models to enable characterization of scattering mechanisms, is briefly discussed.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115543433","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.680569
M. Ready, M. Downey, Leo J. Corbalis
This paper describes a technique for automatically estimating the noise floor spectrum in the presence of signals. The technique works equally well for both flat and non-flat noise floor spectra. The technique is based on applying morphological binary image processing operators to a binary image of the received power spectrum. It is related to rank-order filters but is more computationally efficient. The performance is illustrated on the detection of radio signals.
{"title":"Automatic noise floor spectrum estimation in the presence of signals","authors":"M. Ready, M. Downey, Leo J. Corbalis","doi":"10.1109/ACSSC.1997.680569","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680569","url":null,"abstract":"This paper describes a technique for automatically estimating the noise floor spectrum in the presence of signals. The technique works equally well for both flat and non-flat noise floor spectra. The technique is based on applying morphological binary image processing operators to a binary image of the received power spectrum. It is related to rank-order filters but is more computationally efficient. The performance is illustrated on the detection of radio signals.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123396187","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.680433
A. Ranheim, P. Pelin
A new algorithm for multiuser detection in a DS-CDMA system is presented. Based on an algorithm originally developed in the array-processing context, it minimizes a weighted least-squares criterion, and detects one signal at a time. A performance analysis in terms of the bit-error rate is carried out, and demonstrates that the proposed method is asymptotically identical to the LMMSE-estimator, but without assuming or requiring any knowledge of the signal amplitudes. Only the desired user's signature sequence and timing is required. Both a batch and a recursive formulation of the algorithm is described and simulation results are included in addition to the analysis, to highlight the comparison to other methods.
{"title":"A decoupled WLS approach to DS-CDMA multiuser detection","authors":"A. Ranheim, P. Pelin","doi":"10.1109/ACSSC.1997.680433","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680433","url":null,"abstract":"A new algorithm for multiuser detection in a DS-CDMA system is presented. Based on an algorithm originally developed in the array-processing context, it minimizes a weighted least-squares criterion, and detects one signal at a time. A performance analysis in terms of the bit-error rate is carried out, and demonstrates that the proposed method is asymptotically identical to the LMMSE-estimator, but without assuming or requiring any knowledge of the signal amplitudes. Only the desired user's signature sequence and timing is required. Both a batch and a recursive formulation of the algorithm is described and simulation results are included in addition to the analysis, to highlight the comparison to other methods.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123471230","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.679127
Changlin Chen, J. Dill, Yung-Cheng Lo, A. Lindsey
The uniformity of a new trellis-coded modulation for spread spectrum communications, called high dimensional trellis-coded modulation (HDTCM) is studied. High dimensional trellis-coded modulation integrates a new block code with permuted state structure and a high dimensional signal constellation. It combines not only coding and modulation, but also PN spreading into one single process. The uniformity of the scheme enables us to choose an arbitrary reference during performance analysis which greatly simplifies the performance analysis. The paper proves that high dimensional trellis-coded modulation with a bi-orthogonal signal constellation is a uniform scheme. It further points out that the uniformity of the HDTCM scheme depends upon the uniformity of the signal constellation used.
{"title":"Uniformity of high dimensional trellis-coded modulation","authors":"Changlin Chen, J. Dill, Yung-Cheng Lo, A. Lindsey","doi":"10.1109/ACSSC.1997.679127","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679127","url":null,"abstract":"The uniformity of a new trellis-coded modulation for spread spectrum communications, called high dimensional trellis-coded modulation (HDTCM) is studied. High dimensional trellis-coded modulation integrates a new block code with permuted state structure and a high dimensional signal constellation. It combines not only coding and modulation, but also PN spreading into one single process. The uniformity of the scheme enables us to choose an arbitrary reference during performance analysis which greatly simplifies the performance analysis. The paper proves that high dimensional trellis-coded modulation with a bi-orthogonal signal constellation is a uniform scheme. It further points out that the uniformity of the HDTCM scheme depends upon the uniformity of the signal constellation used.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124259325","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.680533
J. L. Sullivan, J.W. Adams
Peak-constrained least-squares (PCLS) optimization is a relatively new approach to solving digital filter design problems. Motivations for the PCLS optimality criterion are discussed previously. However, the PCLS examples and design methods proposed by Adams (1991) and Adams, Sullivan and Hashemi (1993) are focused on real symmetric FIR digital filters and windows. In this paper we extend the PCLS approach to the design of complex FIR digital filters and windows.
{"title":"PCLS optimization of complex FIR digital filters and windows","authors":"J. L. Sullivan, J.W. Adams","doi":"10.1109/ACSSC.1997.680533","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.680533","url":null,"abstract":"Peak-constrained least-squares (PCLS) optimization is a relatively new approach to solving digital filter design problems. Motivations for the PCLS optimality criterion are discussed previously. However, the PCLS examples and design methods proposed by Adams (1991) and Adams, Sullivan and Hashemi (1993) are focused on real symmetric FIR digital filters and windows. In this paper we extend the PCLS approach to the design of complex FIR digital filters and windows.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128598152","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 : 1997-11-02DOI: 10.1109/ACSSC.1997.679103
D. Wei, A. Bovik
We study the asymptotic behavior of the dual filters associated with biorthogonal spline wavelets (BSWs) and general biorthogonal Coifman wavelets (GBCWs). As the order of wavelet systems approaches infinity the BSW filters either diverge or converge to some non-ideal filters, the GBCW synthesis filters converge to an ideal halfband lowpass (HBLP) filter without exhibiting any Gibbs-like phenomenon, and a subclass of the analysis filters also converge to an ideal HBLP filter but with a one-sided Gibbs-like behavior. The two approximations of the ideal HBLP filter by Daubechies orthonormal wavelet filters and by the GBCW synthesis filters are also compared.
{"title":"Asymptotic convergence of biorthogonal wavelet filters","authors":"D. Wei, A. Bovik","doi":"10.1109/ACSSC.1997.679103","DOIUrl":"https://doi.org/10.1109/ACSSC.1997.679103","url":null,"abstract":"We study the asymptotic behavior of the dual filters associated with biorthogonal spline wavelets (BSWs) and general biorthogonal Coifman wavelets (GBCWs). As the order of wavelet systems approaches infinity the BSW filters either diverge or converge to some non-ideal filters, the GBCW synthesis filters converge to an ideal halfband lowpass (HBLP) filter without exhibiting any Gibbs-like phenomenon, and a subclass of the analysis filters also converge to an ideal HBLP filter but with a one-sided Gibbs-like behavior. The two approximations of the ideal HBLP filter by Daubechies orthonormal wavelet filters and by the GBCW synthesis filters are also compared.","PeriodicalId":240431,"journal":{"name":"Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128534414","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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