{"title":"Algorithm for steering vector estimation using second order moments","authors":"A. Weiss, B. Friedlander","doi":"10.1109/ACSSC.1995.540807","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540807","url":null,"abstract":"The increasing use of the electromagnetic spectrum is expected to present a higher demand for effective methods for interference canceling and signal separation. The goals of signal separation/reconstruction and interference canceling can be achieved by estimating the steering vectors of the array and then exploiting this information. We consider the problem of estimating the steering vectors of an uncalibrated array. The array elements are assumed to have the same unknown gain pattern, up to an unknown multiplicative factor, and the phases are arbitrary and unknown. The signals are assumed to be uncorrelated. We present an estimation algorithm and compare its performance with the Cramer Rao bound.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126625246","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":"Bandpass delta-sigma data converters","authors":"R. Schreier","doi":"10.1109/ACSSC.1995.540520","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540520","url":null,"abstract":"A standard (lowpass) delta-sigma converter uses a sampling frequency which must be many times greater than the highest signal frequency of interest. In contrast, a bandpass delta-sigma data converter needs a sampling rate which is only a few times greater than the highest frequency of interest. Bandpass data converters facilitate high precision analog-to-digital conversion of narrowband bandpass signals in the MHz range. They find application in digital communication systems, spectrum analyzers and special-purpose instrumentation. This paper describes some of the theory behind the technique and summarizes results reported in the literature.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122483091","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 weighted quasi-balanced model reduction method for 2-D discrete systems","authors":"H. Luo, W. Lu, A. Antoniou","doi":"10.1109/ACSSC.1995.540849","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540849","url":null,"abstract":"A new weighted quasi-balanced model reduction method for two-dimensional discrete systems with input and output weights is developed. The development of the new method can be divided into three distinct stages. First is the introduction of four auxiliary Lyapunov equations by which weighted controllability and observability quasi-gramians are defined. The second is the computation of the weighted quasi-gramians. The third is the definition of the weighted quasi-balanced realization. A 2-D filter of order","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122504472","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":"Bayesian approach of multiuser separation and interference suppression in CDMA communication systems","authors":"H. Ge, Y. Bar-Ness","doi":"10.1109/ACSSC.1995.540559","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540559","url":null,"abstract":"Based on Bayesian philosophy, we propose a simplified detection scheme for multiuser separation in CDMA communication systems. The proposed detector uses a multi-stage approach to achieve improved detection performance. In the first stage, we use a marginal Bayesian estimate to get a tentative estimate of the random signal vector. In the second stage, a refined estimate of the multiuser information bit is obtained by incorporating the correlation structure of the noise. This detector avoids the multidimensional integration associated with the general multi-dimensional Bayesian estimate. Simulation results show improved performance over existing detectors of comparable simplicity.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122025720","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":"Robust detection of random signals in exponential mixture noise","authors":"D. Stein","doi":"10.1109/ACSSC.1995.540909","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540909","url":null,"abstract":"Exponential mixture probability density functions (PDFs) are shown to be useful models of the intensity of high resolution low-pulse-rate radar clutter. In this environment, using known parameters, incoherent detection algorithms based upon these noise models have significantly improved performance in comparison with detection algorithms based on exponential PDFs. To implement exponential mixture based detection algorithms, parameters must be estimated from noise only data and applied to the data under test. Certain parameters vary over short range and time segments, and performance is often degraded due to uncertainty in the true parameter values. For the algorithms presented, each parameter is assumed to be known within a certain interval, and valves of the parameters needed by the processor are selected to prevent an excessive number of false alarms. One technique selects certain percentiles for each parameter, and another minimizes the maximum false alarm rate. In addition a high variance state measured globally may be added to the processor. The performance of these algorithms are compared with a CFAR processor using radar data.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116611935","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":"Overlaying multiple users in acoustic communications using MIMO spatial diversity equalization","authors":"Bong-Gee Song, J. Ritcey","doi":"10.1109/ACSSC.1995.540556","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540556","url":null,"abstract":"The available bandwidth of ocean acoustic channels is inherently narrow which impedes high transmission rate and makes it difficult for multiple users to communicate simultaneously. To alleviate this problem, spatial diversity antennas are used in an ocean environment to increase the data rate. We apply spatial diversity equalizers (SDE) to ocean acoustic channels and show that multi-user communication is possible despite the narrow channel bandwidth. In addition, we show that the advantage of SDE is not because of the use of more taps, but because of the data carried through various ocean paths. By applying the saddle point integration method to multi-input multi-output (MIMO) channels, we compute the probability of error (PE) to show that a factor of 3-4 of channel reuse is possible.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117043312","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":"Propagation measurements for 1.9 GHz high-gain antenna array design","authors":"C. M. Keller","doi":"10.1109/ACSSC.1995.540578","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540578","url":null,"abstract":"This paper addresses the benefits achievable with advanced base station antennas for 1.9 GHz personal communications services (PCS). High-gain antennas, multiple sub-aperture diversity combining, and adaptive array processing are all parts of the advanced antenna concept. A measurement program was carried out in urban and suburban environments to preview the performance achievable with large antennas. Results indicate that very tall narrow antenna subarrays can produce the desired high gain while minimizing the amount of beam-steering and beamforming required.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129873256","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":"Experimental study of antenna arrays in indoor wireless applications","authors":"S. Jeng, G. Xu, H. Lin, W. Vogel","doi":"10.1109/ACSSC.1995.540804","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540804","url":null,"abstract":"A spatial signature is the response vector of an antenna array to a mobile unit at a certain location. The mobile subscribers at different locations exhibit different spatial signatures. The exploitation of spatial diversity (or difference of spatial signatures) is the basic idea of the so-called space-division-multiple-access (SDMA) scheme, which can be used to significantly increase the channel capacity and quality and combat multipath fading in a wireless communication system. The purpose of this paper is to describe indoor experiments conducted with our antenna array (or smart antenna) testbed to study the vector channel propagation characteristics in various indoor scenarios. The results to be presented include indoor DOA angle spread and spatial signature variation due to terminal displacement. The experimental results show the rich spatial diversity and potential benefits of using an antenna array for indoor wireless applications, such as wireless local area networks (LANs).","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128966576","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":"Maximum likelihood range localization of waves propagating in a random ocean","authors":"Bong-Gee Song, J. Ritcey, T. Ewart","doi":"10.1109/ACSSC.1995.540817","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540817","url":null,"abstract":"We propose a statistical signal processing solution to the problem of finding a monochromatic source propagating in a random media. The media is fully parameterized by two variables, range X and scattering strength /spl gamma/, which in turn depend upon the physical parameters of the problem. We observe M independent intensity measurements, each drawn form the generalized gamma distribution. The parameters of the distribution are related to the physical parameters, X and /spl gamma/. Maximum likelihood estimates are obtained and the Cramer Rao lower bound is derived. The results show that we can estimate the range to a precision of about 20%, for ranges up to half the distance to the focus of the medium. Simulation results verify both the normality of the estimates and the validity of the CRLB as a predictor of the estimator precision at these ranges. The practical value of this method will depend on our ability to gather enough independent measurements, and on the accuracy of the statistical models.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124770541","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":"Multisensor TDOA estimation in a multipath propagation environment using the EM algorithm","authors":"S. P. Belanger","doi":"10.1109/ACSSC.1995.540869","DOIUrl":"https://doi.org/10.1109/ACSSC.1995.540869","url":null,"abstract":"The expectation-maximization (EM) algorithm is presented as a means of performing passive, high-resolution, intersensor time difference of arrival (TDOA) estimation in the presence of correlated multipath interference and noise. The approach presented here assumes that the signal can be represented as a bandlimited complex Gaussian process, but is otherwise unknown. Within the EM algorithm, a conditional mean estimate of the transmitted signal spectrum is generated and used to determine the direct-path and multipath delays and complex amplitudes associated with each received signal. The delay/amplitude estimator takes the form of nonlinear least-squares optimization problem. The structure of the algorithm is described and its performance demonstrated through simulation.","PeriodicalId":171264,"journal":{"name":"Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125109485","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}