{"title":"Perspectives on custom computing","authors":"Wayne Luk, Henry Styles","doi":"10.1109/ACSSC.2000.910980","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910980","url":null,"abstract":"Custom computing involves customising computations for one or more applications in a given implementation technology. We describe a framework for customising designs using appropriate libraries, compilers, validation facilities, application programming interfaces and front-end tools. The development of custom architectures, data formats and operations is presented. We show how circuits can be customised at run time to adapt to changes in the operating conditions. Graphics examples are used throughout the paper to illustrate our approach.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"1 1","pages":"370-374 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89888165","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}
{"title":"The adaptive matching pursuit algorithm for estimation and equalization of sparse time-varying channels","authors":"S. Cotter, B. Rao","doi":"10.1109/ACSSC.2000.911292","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.911292","url":null,"abstract":"This paper addresses issues related to the estimation and equalization of channels with a large delay spread and an impulse response with significant values only over small regions. For a time-varying environment, an adaptive matching pursuit (AMP) algorithm is considered which updates the channel estimate while exploiting the channel's sparsity. From the channel estimate, the equalizer taps are then derived. We show through simulations that using AMP to track the time-varying channel gives significant improvement in equalization performance over using the LMS or RLS algorithms. We also demonstrate how ANP may be modified to more quickly adapt to a fast time-varying channel.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"93 1","pages":"1772-1776 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75004500","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}
{"title":"Near-optimal selection of transmit antennas for a MIMO channel based on Shannon capacity","authors":"S. Sandhu, R. Nabar, D. Gore, A. Paulraj","doi":"10.1109/ACSSC.2000.911019","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.911019","url":null,"abstract":"Current wireless MIMO (multiple transmit and receive antenna) systems are designed with the assumption that the fading channel is estimated perfectly at the receiver while the transmitter has no channel knowledge. If even a small amount of information is fed back to the transmitter, the capacity of the resulting channel increases appreciably. We consider a low-scattering, quasistatic environment where the matrix channel is rank deficient. Previous results (Gore et al. 2000, and Nabar et al. 2000) for such a channel indicate that channel capacity can be increased by a judicious choice of fewer transmit antennas. The optimal subset of transmit antennas is computed by the receiver as the subset that induces the highest Shannon capacity of all subsets of the same cardinality. Here we describe a computationally efficient, near-optimal search technique for the optimal subset based on classical waterpouring. We also provide enhanced search techniques based on partial waterpouring and uniform pourer allocation over the strongest channel modes that outperform waterpouring at high signal to noise ratios.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"67 1","pages":"567-571 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76066897","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}
{"title":"Reducing power dissipation in complex digital filters by using the quadratic residue number system","authors":"A. D'Amora, A. Nannarelli, M. Re, G. Cardarilli","doi":"10.1109/ACSSC.2000.910639","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910639","url":null,"abstract":"This paper compares in terms of performance, area and power dissipation, a complex FIR filter realized in the traditional two's complement system with a Quadratic Residue Number System (QRNS) based one. The resulting implementations, designed to work at the same clock rate, show that the QRNS filter is almost half the size of the traditional one, and dissipates about one third of the energy.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"72 1","pages":"879-883 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75830723","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}
{"title":"High-resolution sensor array processing in the presence of multiple wideband chirp signals","authors":"A. Gershman, M. Amin, M. Pesavento","doi":"10.1109/ACSSC.2000.910915","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910915","url":null,"abstract":"Estimating the parameters of polynomial-phase and chirp signals in sensor arrays is an important task which is frequently encountered in practical applications. Several authors have approached this problem using the narrow-band setting. In this paper, we present an optimal (maximum likelihood) algorithm for estimating the direction-of-arrival (DOA) and frequency parameters of multiple wideband constant-amplitude polynomial-phase signals. Since the proposed ML estimator is computationally intensive, an approximate solution is considered, originating from the analysis of the likelihood function in the single polynomial-phase signal case. As a result, the so-called polynomial-phase beamformer is obtained. Its simplified version referred to as the chirp beamformer is considered in detail. Explicit expressions for the corresponding Cramer-Rao bound (CRB) are presented as well. The performances of the exact ML algorithm and the chirp beamformer are compared to the CRB.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"154 1","pages":"41-45 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74542558","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}
{"title":"A family of linear complexity likelihood ascent search multiuser detectors for CDMA communications","authors":"Yi Sun","doi":"10.1109/ACSSC.2000.910697","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910697","url":null,"abstract":"We propose a family of likelihood ascent search (LAS) detectors that achieve maximum likelihood detection in a subset of hypotheses whereas their expected per-bit computational complexity is linear in the number of users. The LAS detectors monotonically increase likelihood at every search step, and thus monotonically decrease the error probability and converge to a fixed point in a finite number of steps with probability one. It is proved that the thresholds set up in the LAS detectors are necessary and sufficient for monotonic likelihood ascent for an arbitrary signature crosscorrelation matrix with probability one. Among the LAS detectors, the set of wide-sense sequential LAS (WSLAS) detectors is shown to be a set of local maximum likelihood (LML) detectors defined with neighborhood size one. The properties of the fixed points and their observation regions are studied. Simulations are carried out and verify analytical results.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"26 1","pages":"1163-1167 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74678363","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}
{"title":"When is a maximal invariant hypothesis test better than the GLRT?","authors":"Hyung Soo Kim, Alfred O. Hero","doi":"10.1109/ACSSC.2000.910986","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910986","url":null,"abstract":"There has been considerable interest in applying maximal invariant (MI) hypothesis testing as an alternative to the generalized likelihood ratio test (GLRT). This interest has been motivated by several attractive theoretical properties of MI tests including: exact robustness to variation of nuisance parameters, finite-sample min-max optimality (in some cases), and distributional robustness, i.e. insensitivity to changes in the underlying probability distribution over a particular class. Furthermore, in some important cases the M test gives a reasonable test while the GLRT has worse performance than the trivial coin dip decision rule. However, in other cases, like the deep hide target detection problem, there are regimes (SNR, number of wireless users, coherence bandwidth) for which either of the MI and the GLRT can outperform the other. We discuss conditions under which the MI tests can be expected to outperform the GLRT in the context of a radar imaging and target detection application.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"16 1","pages":"401-405 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72976200","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}
{"title":"Time-varying interference suppression in communication systems using time-frequency signal transforms","authors":"Sanjay Chetwani, A. Papandreou-Suppappola","doi":"10.1109/ACSSC.2000.910997","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.910997","url":null,"abstract":"The Fourier transform (FT) is an analysis tool that is perfectly localized at sinusoidal frequencies. We present a FT generalization (GFT) as a 1-D transform of the frequency-modulation (FM) rate. It is designed to be perfectly localized at the FM rate of signals with linear or non-linear instantaneous frequency in the time-frequency plane. We discuss various important GFT properties, implementation and aliasing issues, and provide examples. We successfully apply the GFT to suppress broadband linear FM interference in spread spectrum communication systems. We demonstrate that this new method also performs well for multicomponent interference, and has a computational advantage over other time-varying techniques. In addition, we show that some examples of the GFT are adequate in reducing dispersive interference in underwater and satellite communication systems.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"25 1","pages":"460-464 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74474622","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}
{"title":"Illustration of the duality between channel coding and rate distortion with side information","authors":"J. Su, J. Eggers, B. Girod","doi":"10.1109/ACSSC.2000.911306","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.911306","url":null,"abstract":"Digital watermarking can be viewed as channel coding with side information at the encoder (CC-SI); the original data to be watermarked is known to the encoder but not the decoder. Likewise, distributed source coding is rate distortion with side information at the decoder (RD-SI); a noisy observation of the source data to be compressed is available to the decoder but not the encoder. For a Gaussian channel or source, CC-SI and RD-SI are shown to be information-theoretic duals. Ideal coding schemes are presented, and the schemes are interpreted geometrically to highlight dual elements and quantities.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"45 1","pages":"1841-1845 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73321058","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}
C.C. Martin, J. Winters, H. Zeng, N. Sollenberger, A. Dixit
{"title":"Multiple-input multiple-output (MIMO) radio channel measurements and experimental implementation for EDGE","authors":"C.C. Martin, J. Winters, H. Zeng, N. Sollenberger, A. Dixit","doi":"10.1109/ACSSC.2000.911050","DOIUrl":"https://doi.org/10.1109/ACSSC.2000.911050","url":null,"abstract":"In this paper we present results from the first field test to characterize the mobile multiple-input multiple-output (MIMO) radio channel. We measured the capacity, normalized to a single antenna system, and fading correlation between antennas of a system with 4 antennas on a laptop computer and 4 antennas at a rooftop base station. The field test results show that close to the theoretical 4 times the capacity of a single antenna system can be supported in a 30 kHz channel with dual-polarized, spatially-separated base station and terminal antennas under a variety of test runs, including suburban drives, highway drives, and pedestrian routes. Therefore, these results show that it may he possible to provide in excess of 1 Mbps in a 200 kHz mobile radio channel (for the 3G wireless TDMA system EDGE) with the appropriate base station antennas. To test the performance of MIMO for EDGE we have built a real-time experimental system with 2 transmitters and a 2-branch receiver. In this paper we describe the system implementation and present simulation results for 2/spl times/2 MIMO-EDGE showing only a 2 dB degradation due to channel estimation.","PeriodicalId":10581,"journal":{"name":"Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)","volume":"134 1","pages":"738-742 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2000-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73962932","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}