Pub Date : 2000-10-29DOI: 10.1109/ACSSC.2000.911278
Manish Bhardwaj, R. Min, Anantha Chandrakasan
The key to maximizing energy efficiency of systems is understanding and systematically harnessing the tremendous operational diversity they exhibit. We define the power awareness of a system as its ability to minimize energy consumption by adapting to changes in its operating point. These changes occur as a result of variations in input statistics, desired output quality, tolerable latency and throughput. The key objective of this paper is to unambiguously define the notion of power-awareness, distinguish it from the better understood concept of low-power; to propose a systematic methodology that enhances power-awareness and finally to illustrate the impact of such re-engineering. By applying power-awareness formalisms to systems ranging from multipliers to variable voltage processors, we demonstrate increases in energy efficiency of 60%-200%.
{"title":"Power-aware systems","authors":"Manish Bhardwaj, R. Min, Anantha Chandrakasan","doi":"10.1109/ACSSC.2000.911278","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.911278","url":null,"abstract":"The key to maximizing energy efficiency of systems is understanding and systematically harnessing the tremendous operational diversity they exhibit. We define the power awareness of a system as its ability to minimize energy consumption by adapting to changes in its operating point. These changes occur as a result of variations in input statistics, desired output quality, tolerable latency and throughput. The key objective of this paper is to unambiguously define the notion of power-awareness, distinguish it from the better understood concept of low-power; to propose a systematic methodology that enhances power-awareness and finally to illustrate the impact of such re-engineering. By applying power-awareness formalisms to systems ranging from multipliers to variable voltage processors, we demonstrate increases in energy efficiency of 60%-200%.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"27 1","pages":"1695-1701 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85703661","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.910761
M. Chevalier, S. Blatt, D. Mills, A. Swami
Microsensor networks have been proposed for remote sensing applications. These ad-hoc networks may have thousands of nodes; apart from the important scaling issues, interesting problems arise in designing protocols and routing algorithms that maximize the lifetime of the network subject to constraints on bandwidth and energy and complexities due to mobility and changing topology. The network must be able to self-configure and self-localize. This paper gives an overview of the issues involved and then focuses on using multiple network reconfigurations and local fusion to increase the overall system lifetime.
{"title":"Networking issues in large microsensor nets","authors":"M. Chevalier, S. Blatt, D. Mills, A. Swami","doi":"10.1109/ACSSC.2000.910761","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910761","url":null,"abstract":"Microsensor networks have been proposed for remote sensing applications. These ad-hoc networks may have thousands of nodes; apart from the important scaling issues, interesting problems arise in designing protocols and routing algorithms that maximize the lifetime of the network subject to constraints on bandwidth and energy and complexities due to mobility and changing topology. The network must be able to self-configure and self-localize. This paper gives an overview of the issues involved and then focuses on using multiple network reconfigurations and local fusion to increase the overall system lifetime.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"35 1","pages":"1240-1244 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84148523","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.910773
J. Tuqan
The design of orthogonal multirate finite order digital filters for data transmission over noisy channels has received considerable attention, due to the fact that, these filters play a key role in multicarrier communication systems such as xDSL and CDMA. The problem of designing such filters for maximum energy concentration in the channel bandwidth is revisited. The key constraint in this work is the computational efficiency of the filter design procedure as well as the cost of implementing the filter. For the FIR case, we propose a new semidefinite program (SDP) formulation. The SDP finds the globally optimum product filter H(z)H(z/sup -1/) and is more efficient than the existing solution. A new characterization of the minimum phase spectral factor H/sub min/(z) is also presented. We then consider the optimum design of a special class of IIR multirate filters, namely the class of IIR filters that are the sum of two all pass. Despite its constrained nature, we show that a low order IIR filter can be as "spectrally efficient" as an FIR filter with much more parameters.
{"title":"On the design of optimal orthogonal finite order transmitter and receiver filters for data transmission over noisy channels","authors":"J. Tuqan","doi":"10.1109/ACSSC.2000.910773","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910773","url":null,"abstract":"The design of orthogonal multirate finite order digital filters for data transmission over noisy channels has received considerable attention, due to the fact that, these filters play a key role in multicarrier communication systems such as xDSL and CDMA. The problem of designing such filters for maximum energy concentration in the channel bandwidth is revisited. The key constraint in this work is the computational efficiency of the filter design procedure as well as the cost of implementing the filter. For the FIR case, we propose a new semidefinite program (SDP) formulation. The SDP finds the globally optimum product filter H(z)H(z/sup -1/) and is more efficient than the existing solution. A new characterization of the minimum phase spectral factor H/sub min/(z) is also presented. We then consider the optimum design of a special class of IIR multirate filters, namely the class of IIR filters that are the sum of two all pass. Despite its constrained nature, we show that a low order IIR filter can be as \"spectrally efficient\" as an FIR filter with much more parameters.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"85 1","pages":"1303-1307 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72805913","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.910914
M. Zatman
The rotation of an antenna array will degrade the accuracy and precision of superresolution algorithms used to estimate the directions of arrival of the signals present. The degradation is caused by the apparent motion of the signals during the period that the spatial covariance matrix is being estimated. In this paper a new method which compensates for the apparent motion is presented. The technique succeeds in reducing both the bias and variance of the direction finding results. Performance examples are shown for the popular root-MUSIC algorithm.
{"title":"Superresolution direction finding with rotating arrays","authors":"M. Zatman","doi":"10.1109/ACSSC.2000.910914","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910914","url":null,"abstract":"The rotation of an antenna array will degrade the accuracy and precision of superresolution algorithms used to estimate the directions of arrival of the signals present. The degradation is caused by the apparent motion of the signals during the period that the spatial covariance matrix is being estimated. In this paper a new method which compensates for the apparent motion is presented. The technique succeeds in reducing both the bias and variance of the direction finding results. Performance examples are shown for the popular root-MUSIC algorithm.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"35 1","pages":"36-40 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81343239","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.910658
M. Baissas, A. Sayeed
This paper studies the impact of channel estimation errors and Doppler diversity on the performance of coherent CDMA receivers under fast fading. A key channel characteristic controlling performance is the coherence time over which the channel remains strongly correlated. We analyze a time-frequency RAKE receiver structure that exploits joint multipath-Doppler diversity. Modeling of channel estimation errors is based on the performance of pilot-based estimators tailored to the receiver structure. It is shown that the overall performance is controlled by two competing effects: shorter coherence times lead to degraded channel estimation but inherently higher (Doppler) diversity, with opposite effects for longer coherence times. Our results demonstrate that Doppler diversity gains dominate under certain conditions and can significantly mitigate the error probability floors that plague the performance of conventional CDMA receivers under fast fading.
{"title":"Channel estimation errors versus Doppler diversity in fast fading channels","authors":"M. Baissas, A. Sayeed","doi":"10.1109/ACSSC.2000.910658","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910658","url":null,"abstract":"This paper studies the impact of channel estimation errors and Doppler diversity on the performance of coherent CDMA receivers under fast fading. A key channel characteristic controlling performance is the coherence time over which the channel remains strongly correlated. We analyze a time-frequency RAKE receiver structure that exploits joint multipath-Doppler diversity. Modeling of channel estimation errors is based on the performance of pilot-based estimators tailored to the receiver structure. It is shown that the overall performance is controlled by two competing effects: shorter coherence times lead to degraded channel estimation but inherently higher (Doppler) diversity, with opposite effects for longer coherence times. Our results demonstrate that Doppler diversity gains dominate under certain conditions and can significantly mitigate the error probability floors that plague the performance of conventional CDMA receivers under fast fading.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"31 1","pages":"970-974 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81662114","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.911308
L. Gang, A. Akansu, M. Ramkumar
In the oblivious watermarking, information is extracted without reference to the original host signal, whose energy is much larger than that of the watermark signal. Suppressing host noise is a great concern. Some non-linear embedding methods, e.g. quantization index modulation (QIM) can greatly suppress the host noise. In this method, the signaling is periodic. We analyze the maximum likelihood (ML) detector for the QIM signaling scheme, and compare the error probability with a hard decision detector. Based on it, a new periodic signaling scheme is proposed and its optimum and suboptimal detection is derived. Through analysis and simulation, we demonstrate its advantage in term of PE-SNR over the existing methods.
{"title":"Periodic signaling scheme in oblivious data hiding","authors":"L. Gang, A. Akansu, M. Ramkumar","doi":"10.1109/ACSSC.2000.911308","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.911308","url":null,"abstract":"In the oblivious watermarking, information is extracted without reference to the original host signal, whose energy is much larger than that of the watermark signal. Suppressing host noise is a great concern. Some non-linear embedding methods, e.g. quantization index modulation (QIM) can greatly suppress the host noise. In this method, the signaling is periodic. We analyze the maximum likelihood (ML) detector for the QIM signaling scheme, and compare the error probability with a hard decision detector. Based on it, a new periodic signaling scheme is proposed and its optimum and suboptimal detection is derived. Through analysis and simulation, we demonstrate its advantage in term of PE-SNR over the existing methods.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"50 1","pages":"1851-1855 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82260801","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.910675
Marco Grangetto, E. Magli, G. Olmo
In this paper the progressive quadtree wavelet (PQW) codec for lossy image compression is presented. PQW is based on the well known quadtree technique, applied in the wavelet transform domain. The proposed algorithm is designed with the aim of achieving low complexity and reduced memory requirements, keeping in mind applications such as Internet browsing on wireless (e.g. UMTS) channels. Besides its lower complexity, PQW provides the same subjective performance as the popular SPIHT codec while, in terms of the peak signal-to-noise ratio, it exhibits a slight performance loss of about 0.5 dB.
{"title":"A novel low complexity and efficient progressive quadtree wavelet encoder","authors":"Marco Grangetto, E. Magli, G. Olmo","doi":"10.1109/ACSSC.2000.910675","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910675","url":null,"abstract":"In this paper the progressive quadtree wavelet (PQW) codec for lossy image compression is presented. PQW is based on the well known quadtree technique, applied in the wavelet transform domain. The proposed algorithm is designed with the aim of achieving low complexity and reduced memory requirements, keeping in mind applications such as Internet browsing on wireless (e.g. UMTS) channels. Besides its lower complexity, PQW provides the same subjective performance as the popular SPIHT codec while, in terms of the peak signal-to-noise ratio, it exhibits a slight performance loss of about 0.5 dB.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"45 1","pages":"1049-1053 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82491808","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.910912
B. Friedlander
The problem of space-time adaptive processing (STAP) using a circular array is considered. A key part of STAP is the estimation of the space-time covariance matrix of the received data. The conventional method of doing this can be shown to cause performance degradation at short ranges. We present a method based on steering vector interpolation to remedy this problem. The method applied linear transformations to the data from adjacent range cells. the transformed data are then used to form the sample covariance matrix. Numerical examples illustrate significant performance improvement when using the transformed rather than the original data.
{"title":"The MVDR beamformer for circular arrays","authors":"B. Friedlander","doi":"10.1109/ACSSC.2000.910912","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910912","url":null,"abstract":"The problem of space-time adaptive processing (STAP) using a circular array is considered. A key part of STAP is the estimation of the space-time covariance matrix of the received data. The conventional method of doing this can be shown to cause performance degradation at short ranges. We present a method based on steering vector interpolation to remedy this problem. The method applied linear transformations to the data from adjacent range cells. the transformed data are then used to form the sample covariance matrix. Numerical examples illustrate significant performance improvement when using the transformed rather than the original data.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"110 1","pages":"25-29 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76347441","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.911045
A. Reial, S.G. Wilson
A serially concatenated space-time encoder is proposed that can utilize the high capacities available for large-dimensional multiple-transmitter, multiple-receiver wireless systems under fading conditions. For sufficiently long block lengths, it satisfies the code state complexity lower bounds and the rank criterion required for maximal diversity. A 3-stage iterative decoding structure, treating the modulator and channel stages as an additional encoder in serial concatenation, is presented. Its decoding complexity is non-exponential in the number of antennas or the transmission bit rate and it also provides a performance gain compared to the traditional, 2-stage exponential-complexity decoding.
{"title":"Concatenated space-time coding","authors":"A. Reial, S.G. Wilson","doi":"10.1109/ACSSC.2000.911045","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.911045","url":null,"abstract":"A serially concatenated space-time encoder is proposed that can utilize the high capacities available for large-dimensional multiple-transmitter, multiple-receiver wireless systems under fading conditions. For sufficiently long block lengths, it satisfies the code state complexity lower bounds and the rank criterion required for maximal diversity. A 3-stage iterative decoding structure, treating the modulator and channel stages as an additional encoder in serial concatenation, is presented. Its decoding complexity is non-exponential in the number of antennas or the transmission bit rate and it also provides a performance gain compared to the traditional, 2-stage exponential-complexity decoding.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"15 1","pages":"710-715 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82836069","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 : 2000-10-29DOI: 10.1109/ACSSC.2000.910767
Zhengyuan Xu
The precoder has been shown to be able to provide source diversity and more freedom in design. In this paper we employ precoding techniques for block transmission based on a multirate filterbank structure. To meet multiuser communication requirements for various high data-rates, different filterbanks are used as precoders with corresponding coefficients and up/down sampling rates. However due to high speed communication in the presence of unknown multipath, different interferences exist in the received data such as multiuser interference, intersymbol interference and interblock interference. To estimate the multipath channel for a desired user we generalize the subspace method by employing all signatures associated with this channel in the current system. In this way a better performance for the channel estimate can be achieved. The delay for that user can also be jointly estimated together with channel estimation.
{"title":"Blind channel estimation for precoded variable bit-rate multiuser systems","authors":"Zhengyuan Xu","doi":"10.1109/ACSSC.2000.910767","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910767","url":null,"abstract":"The precoder has been shown to be able to provide source diversity and more freedom in design. In this paper we employ precoding techniques for block transmission based on a multirate filterbank structure. To meet multiuser communication requirements for various high data-rates, different filterbanks are used as precoders with corresponding coefficients and up/down sampling rates. However due to high speed communication in the presence of unknown multipath, different interferences exist in the received data such as multiuser interference, intersymbol interference and interblock interference. To estimate the multipath channel for a desired user we generalize the subspace method by employing all signatures associated with this channel in the current system. In this way a better performance for the channel estimate can be achieved. The delay for that user can also be jointly estimated together with channel estimation.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"37 1","pages":"1273-1277 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88871888","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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