The Experts below are selected from a list of 171995979 Experts worldwide ranked by ideXlab platform
M A Jensen - One of the best experts on this subject based on the ideXlab platform.
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modeling the statistical time and angle of arrival characteristics of an indoor multipath channel
IEEE Journal on Selected Areas in Communications, 2000Co-Authors: Q H Spencer, B D Jeffs, M A Jensen, A L SwindlehurstAbstract:Most previously proposed statistical models for the indoor multipath channel include only time of arrival characteristics. However, in order to use statistical models in simulating or analyzing the performance of systems employing spatial diversity combining, information about angle of arrival statistics is also required. Ideally, it would be desirable to characterize the full spare-time nature of the channel. In this paper, a system is described that was used to collect simultaneous time and angle of arrival data at 7 GHz. Data processing methods are outlined, and results obtained from data taken in two different buildings are presented. Based on the results, a model is proposed that employs the clustered "double Poisson" time-of-arrival model proposed by Saleh and Valenzuela (1987). The observed angular distribution is also clustered with uniformly distributed clusters and arrivals within clusters that have a Laplacian distribution.
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indoor wideband time angle of arrival multipath propagation results
Vehicular Technology Conference, 1997Co-Authors: Quentin Spencer, B D Jeffs, Michael Rice, M A JensenAbstract:Most current indoor propagation experiments measure the time of arrival of characteristics of multipath reflections without regard to the angle of arrival. Because of the increasing number of systems that are used indoors and which use multiple antenna systems to combat multipath interference, a need exists for indoor propagation data which takes the angle of arrival into account. A system is described which was used to collect simultaneous time and angle of arrival data in two indoor environments. A total of 65 data sets were taken in two buildings of different construction. The (7 GHz) data confirmed the temporal model proposed by Saleh and Valenzuela (1987), and showed a unique clustering pattern in angle, which consisted of clusters uniformly distributed in angle, with members of the clusters following a Laplacian distribution.
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a statistical model for angle of arrival in indoor multipath propagation
Vehicular Technology Conference, 1997Co-Authors: Quentin Spencer, Michael Rice, B Jeffs, M A JensenAbstract:Multiple antenna systems are a useful way of overcoming the effects of multipath interference, and can allow more efficient use of spectrum. In order to test the effectiveness of various algorithms such as diversity combining, phased array processing, and adaptive array processing in an indoor environment, a channel model is needed which models both the time and angle of arrival in indoor environments. Some data has been collected indoors and some temporal models have been proposed, but no existing model accounts for both time and angle of arrival. This paper discusses existing models for the time of arrival, experimental data (form the 6.75-7.25 GHz band) that were collected indoors, and a proposed extension of the Saleh-Valenzuela model (1987), which accounts for the angle of arrival. Model parameters measured in two different buildings are compared with the parameters presented in the paper by Saleh and Valenzuela, and some statistical validation of the model is presented.
Dale S Sawyer - One of the best experts on this subject based on the ideXlab platform.
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assessment of crustal velocity models using seismic refraction and reflection tomography
Geophysical Journal International, 2003Co-Authors: C A Zelt, Kalachand Sain, Julia V Naumenko, Dale S SawyerAbstract:Two tomographic methods for assessing velocity models obtained from wide-angle seismic traveltime data are presented through four case studies. The modelling/inversion of wide-angle traveltimes usually involves some aspects that are quite subjective. For example: (1) identifying and including later phases that are often difficult to pick within the seismic coda, (2) assigning specific layers to arrivals, (3) incorporating pre-conceived structure not specifically required by the data and (4) selecting a model parametrization. These steps are applied to maximize model constraint and minimize model non-uniqueness. However, these steps may cause the overall approach to appear ad hoc, and thereby diminish the credibility of the final model. The effect of these subjective choices can largely be addressed by estimating the minimum model structure required by the least subjective portion of the wide-angle data set: the first-arrival times. For data sets with Moho reflections, the tomographic velocity model can be used to invert the PmP times for a minimum-structure Moho. In this way, crustal velocity and Moho models can be obtained that require the least amount of subjective input, and the model structure that is required by the wide-angle data with a high degree of certainty can be differentiated from structure that is merely consistent with the data. The tomographic models are not intended to supersede the preferred models, since the latter model is typically better resolved and more interpretable. This form of tomographic assessment is intended to lend credibility to model features common to the tomographic and preferred models. Four case studies are presented in which a preferred model was derived using one or more of the subjective steps described above. This was followed by conventional first-arrival and reflection traveltime tomography using a finely gridded model parametrization to derive smooth, minimum-structure models. The case studies are from the SE Canadian Cordillera across the Rocky Mountain Trench, central India across the Narmada-Son lineament, the Iberia margin across the Galicia Bank, and the central Chilean margin across the Valparaiso Basin and a subducting seamount. These case studies span the range of modern wide-angle experiments and data sets in terms of shot‐receiver spacing, marine and land acquisition, lateral heterogeneity of the study area, and availability of wide-angle reflections and coincident near-vertical reflection data. The results are surprising given the amount of structure in the smooth, tomographically derived models that is consistent with the more subjectively derived models. The results show that exploiting the complementary nature of the subjective and tomographic approaches is an effective strategy for the analysis of wide-angle traveltime data.
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assessment of crustal velocity models using seismic refraction and reflection tomography
Geophysical Journal International, 2003Co-Authors: C A Zelt, Kalachand Sain, Julia V Naumenko, Dale S SawyerAbstract:Two tomographic methods for assessing velocity models obtained from wide-angle seismic traveltime data are presented through four case studies. The modelling/inversion of wide-angle traveltimes usually involves some aspects that are quite subjective. For example: (1) identifying and including later phases that are often difficult to pick within the seismic coda, (2) assigning specific layers to arrivals, (3) incorporating pre-conceived structure not specifically required by the data and (4) selecting a model parametrization. These steps are applied to maximize model constraint and minimize model non-uniqueness. However, these steps may cause the overall approach to appear ad hoc, and thereby diminish the credibility of the final model. The effect of these subjective choices can largely be addressed by estimating the minimum model structure required by the least subjective portion of the wide-angle data set: the first-arrival times. For data sets with Moho reflections, the tomographic velocity model can be used to invert the PmP times for a minimum-structure Moho. In this way, crustal velocity and Moho models can be obtained that require the least amount of subjective input, and the model structure that is required by the wide-angle data with a high degree of certainty can be differentiated from structure that is merely consistent with the data. The tomographic models are not intended to supersede the preferred models, since the latter model is typically better resolved and more interpretable. This form of tomographic assessment is intended to lend credibility to model features common to the tomographic and preferred models. Four case studies are presented in which a preferred model was derived using one or more of the subjective steps described above. This was followed by conventional first-arrival and reflection traveltime tomography using a finely gridded model parametrization to derive smooth, minimum-structure models. The case studies are from the SE Canadian Cordillera across the Rocky Mountain Trench, central India across the Narmada-Son lineament, the Iberia margin across the Galicia Bank, and the central Chilean margin across the Valparaiso Basin and a subducting seamount. These case studies span the range of modern wide-angle experiments and data sets in terms of shot‐receiver spacing, marine and land acquisition, lateral heterogeneity of the study area, and availability of wide-angle reflections and coincident near-vertical reflection data. The results are surprising given the amount of structure in the smooth, tomographically derived models that is consistent with the more subjectively derived models. The results show that exploiting the complementary nature of the subjective and tomographic approaches is an effective strategy for the analysis of wide-angle traveltime data.
Quentin Spencer - One of the best experts on this subject based on the ideXlab platform.
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indoor wideband time angle of arrival multipath propagation results
Vehicular Technology Conference, 1997Co-Authors: Quentin Spencer, B D Jeffs, Michael Rice, M A JensenAbstract:Most current indoor propagation experiments measure the time of arrival of characteristics of multipath reflections without regard to the angle of arrival. Because of the increasing number of systems that are used indoors and which use multiple antenna systems to combat multipath interference, a need exists for indoor propagation data which takes the angle of arrival into account. A system is described which was used to collect simultaneous time and angle of arrival data in two indoor environments. A total of 65 data sets were taken in two buildings of different construction. The (7 GHz) data confirmed the temporal model proposed by Saleh and Valenzuela (1987), and showed a unique clustering pattern in angle, which consisted of clusters uniformly distributed in angle, with members of the clusters following a Laplacian distribution.
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a statistical model for angle of arrival in indoor multipath propagation
Vehicular Technology Conference, 1997Co-Authors: Quentin Spencer, Michael Rice, B Jeffs, M A JensenAbstract:Multiple antenna systems are a useful way of overcoming the effects of multipath interference, and can allow more efficient use of spectrum. In order to test the effectiveness of various algorithms such as diversity combining, phased array processing, and adaptive array processing in an indoor environment, a channel model is needed which models both the time and angle of arrival in indoor environments. Some data has been collected indoors and some temporal models have been proposed, but no existing model accounts for both time and angle of arrival. This paper discusses existing models for the time of arrival, experimental data (form the 6.75-7.25 GHz band) that were collected indoors, and a proposed extension of the Saleh-Valenzuela model (1987), which accounts for the angle of arrival. Model parameters measured in two different buildings are compared with the parameters presented in the paper by Saleh and Valenzuela, and some statistical validation of the model is presented.
C A Zelt - One of the best experts on this subject based on the ideXlab platform.
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assessment of crustal velocity models using seismic refraction and reflection tomography
Geophysical Journal International, 2003Co-Authors: C A Zelt, Kalachand Sain, Julia V Naumenko, Dale S SawyerAbstract:Two tomographic methods for assessing velocity models obtained from wide-angle seismic traveltime data are presented through four case studies. The modelling/inversion of wide-angle traveltimes usually involves some aspects that are quite subjective. For example: (1) identifying and including later phases that are often difficult to pick within the seismic coda, (2) assigning specific layers to arrivals, (3) incorporating pre-conceived structure not specifically required by the data and (4) selecting a model parametrization. These steps are applied to maximize model constraint and minimize model non-uniqueness. However, these steps may cause the overall approach to appear ad hoc, and thereby diminish the credibility of the final model. The effect of these subjective choices can largely be addressed by estimating the minimum model structure required by the least subjective portion of the wide-angle data set: the first-arrival times. For data sets with Moho reflections, the tomographic velocity model can be used to invert the PmP times for a minimum-structure Moho. In this way, crustal velocity and Moho models can be obtained that require the least amount of subjective input, and the model structure that is required by the wide-angle data with a high degree of certainty can be differentiated from structure that is merely consistent with the data. The tomographic models are not intended to supersede the preferred models, since the latter model is typically better resolved and more interpretable. This form of tomographic assessment is intended to lend credibility to model features common to the tomographic and preferred models. Four case studies are presented in which a preferred model was derived using one or more of the subjective steps described above. This was followed by conventional first-arrival and reflection traveltime tomography using a finely gridded model parametrization to derive smooth, minimum-structure models. The case studies are from the SE Canadian Cordillera across the Rocky Mountain Trench, central India across the Narmada-Son lineament, the Iberia margin across the Galicia Bank, and the central Chilean margin across the Valparaiso Basin and a subducting seamount. These case studies span the range of modern wide-angle experiments and data sets in terms of shot‐receiver spacing, marine and land acquisition, lateral heterogeneity of the study area, and availability of wide-angle reflections and coincident near-vertical reflection data. The results are surprising given the amount of structure in the smooth, tomographically derived models that is consistent with the more subjectively derived models. The results show that exploiting the complementary nature of the subjective and tomographic approaches is an effective strategy for the analysis of wide-angle traveltime data.
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assessment of crustal velocity models using seismic refraction and reflection tomography
Geophysical Journal International, 2003Co-Authors: C A Zelt, Kalachand Sain, Julia V Naumenko, Dale S SawyerAbstract:Two tomographic methods for assessing velocity models obtained from wide-angle seismic traveltime data are presented through four case studies. The modelling/inversion of wide-angle traveltimes usually involves some aspects that are quite subjective. For example: (1) identifying and including later phases that are often difficult to pick within the seismic coda, (2) assigning specific layers to arrivals, (3) incorporating pre-conceived structure not specifically required by the data and (4) selecting a model parametrization. These steps are applied to maximize model constraint and minimize model non-uniqueness. However, these steps may cause the overall approach to appear ad hoc, and thereby diminish the credibility of the final model. The effect of these subjective choices can largely be addressed by estimating the minimum model structure required by the least subjective portion of the wide-angle data set: the first-arrival times. For data sets with Moho reflections, the tomographic velocity model can be used to invert the PmP times for a minimum-structure Moho. In this way, crustal velocity and Moho models can be obtained that require the least amount of subjective input, and the model structure that is required by the wide-angle data with a high degree of certainty can be differentiated from structure that is merely consistent with the data. The tomographic models are not intended to supersede the preferred models, since the latter model is typically better resolved and more interpretable. This form of tomographic assessment is intended to lend credibility to model features common to the tomographic and preferred models. Four case studies are presented in which a preferred model was derived using one or more of the subjective steps described above. This was followed by conventional first-arrival and reflection traveltime tomography using a finely gridded model parametrization to derive smooth, minimum-structure models. The case studies are from the SE Canadian Cordillera across the Rocky Mountain Trench, central India across the Narmada-Son lineament, the Iberia margin across the Galicia Bank, and the central Chilean margin across the Valparaiso Basin and a subducting seamount. These case studies span the range of modern wide-angle experiments and data sets in terms of shot‐receiver spacing, marine and land acquisition, lateral heterogeneity of the study area, and availability of wide-angle reflections and coincident near-vertical reflection data. The results are surprising given the amount of structure in the smooth, tomographically derived models that is consistent with the more subjectively derived models. The results show that exploiting the complementary nature of the subjective and tomographic approaches is an effective strategy for the analysis of wide-angle traveltime data.
Michael Rice - One of the best experts on this subject based on the ideXlab platform.
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indoor wideband time angle of arrival multipath propagation results
Vehicular Technology Conference, 1997Co-Authors: Quentin Spencer, B D Jeffs, Michael Rice, M A JensenAbstract:Most current indoor propagation experiments measure the time of arrival of characteristics of multipath reflections without regard to the angle of arrival. Because of the increasing number of systems that are used indoors and which use multiple antenna systems to combat multipath interference, a need exists for indoor propagation data which takes the angle of arrival into account. A system is described which was used to collect simultaneous time and angle of arrival data in two indoor environments. A total of 65 data sets were taken in two buildings of different construction. The (7 GHz) data confirmed the temporal model proposed by Saleh and Valenzuela (1987), and showed a unique clustering pattern in angle, which consisted of clusters uniformly distributed in angle, with members of the clusters following a Laplacian distribution.
-
a statistical model for angle of arrival in indoor multipath propagation
Vehicular Technology Conference, 1997Co-Authors: Quentin Spencer, Michael Rice, B Jeffs, M A JensenAbstract:Multiple antenna systems are a useful way of overcoming the effects of multipath interference, and can allow more efficient use of spectrum. In order to test the effectiveness of various algorithms such as diversity combining, phased array processing, and adaptive array processing in an indoor environment, a channel model is needed which models both the time and angle of arrival in indoor environments. Some data has been collected indoors and some temporal models have been proposed, but no existing model accounts for both time and angle of arrival. This paper discusses existing models for the time of arrival, experimental data (form the 6.75-7.25 GHz band) that were collected indoors, and a proposed extension of the Saleh-Valenzuela model (1987), which accounts for the angle of arrival. Model parameters measured in two different buildings are compared with the parameters presented in the paper by Saleh and Valenzuela, and some statistical validation of the model is presented.