The Experts below are selected from a list of 5862 Experts worldwide ranked by ideXlab platform
Akihiro Kajiwara - One of the best experts on this subject based on the ideXlab platform.
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VTC Fall - Power Delay Profile Matching for Vehicle Target Recognition
2009 IEEE 70th Vehicular Technology Conference Fall, 2009Co-Authors: Isamu Matsunami, Youichiro Nakahata, Akihiro KajiwaraAbstract:Radar echo contains unwanted echoes called as clutter, which make it difficult to detect vehicle or obstacle. Especially short-range/wide-angle vehicle radar at 24GHz suffers from heavy clutter unlike long-range radar at 77GHz. It is therefore expect to improve the detection performance by suppressing the clutter using a pulse integration and CFAR (Constant False Alarm Rate). However the radar echo should include multiple vehicle targets as well as the clutter, thereby it is not easy to improve the performance. In this paper the target discrimination technique, let say, power Delay Profile matching scheme is proposed and the usefulness is investigated by conducting the measurement at 24GHz where the clutter suppression scheme is also considered. As a result, a vehicle target is found to be recognized from multiple vehicles. We have also investigated the effect of bandwidth on the target discrimination capability.
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Power Delay Profile Matching for Vehicle Target Recognition
2009 IEEE 70th Vehicular Technology Conference Fall, 2009Co-Authors: Isamu Matsunami, Youichiro Nakahata, Akihiro KajiwaraAbstract:Radar echo contains unwanted echoes called as clutter, which make it difficult to detect vehicle or obstacle. Especially short-range/wide-angle vehicle radar at 24 GHz suffers from heavy clutter unlike long-range radar at 77 GHz. It is therefore expect to improve the detection performance by suppressing the clutter using a pulse integration and CFAR (Constant False Alarm Rate). However the radar echo should include multiple vehicle targets as well as the clutter, thereby it is not easy to improve the performance. In this paper the target discrimination technique, let say, power Delay Profile matching scheme is proposed and the usefulness is investigated by conducting the measurement at 24 GHz where the clutter suppression scheme is also considered. As a result, a vehicle target is found to be recognized from multiple vehicles. We have also investigated the effect of bandwidth on the target discrimination capability.
Jinhong Yuan - One of the best experts on this subject based on the ideXlab platform.
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Channel Estimation in OFDM Systems With Unknown Power Delay Profile Using Transdimensional MCMC
IEEE Transactions on Signal Processing, 2009Co-Authors: Gareth W. Peters, Ido Nevat, Jinhong YuanAbstract:This paper considers the problem of channel estimation for orthogonal-frequency-division multiplexing (OFDM) systems, where the number of channel taps and their power Delay Profile are unknown. Using a Bayesian approach, we construct a model in which we estimate jointly the coefficients of the channel taps, the channel order and decay rate of the power Delay Profile (PDP). In order to sample from the resulting posterior distribution we develop three novel Trans-dimensional Markov chain Monte Carlo (TDMCMC) algorithms and compare their performance. The first is the basic birth and death TDMCMC algorithm. The second utilizes Stochastic Approximation to develop an adaptively learning algorithm to improve mixing rates of the Markov chain between model subspaces. The third approximates the optimal TDMCMC proposal distribution for between-model moves using conditional path sampling proposals. We assess several aspects of the model in terms of sensitivities to different prior choices. Next we perform a detailed analysis of the performance of each of the TDMCMC algorithms. This allows us to contrast the resulting computational effort required under each approach versus the estimation performance. Finally, using the TDMCMC algorithm which produces the best performance in terms of exploration of the model subspaces, we assess its performance in terms of channel estimation mean-square error (MSE) and bit error rate (BER). It is shown that the proposed algorithm can achieve results very close to the case where both the channel length and the PDP decay rate are known.
Isamu Matsunami - One of the best experts on this subject based on the ideXlab platform.
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VTC Fall - Power Delay Profile Matching for Vehicle Target Recognition
2009 IEEE 70th Vehicular Technology Conference Fall, 2009Co-Authors: Isamu Matsunami, Youichiro Nakahata, Akihiro KajiwaraAbstract:Radar echo contains unwanted echoes called as clutter, which make it difficult to detect vehicle or obstacle. Especially short-range/wide-angle vehicle radar at 24GHz suffers from heavy clutter unlike long-range radar at 77GHz. It is therefore expect to improve the detection performance by suppressing the clutter using a pulse integration and CFAR (Constant False Alarm Rate). However the radar echo should include multiple vehicle targets as well as the clutter, thereby it is not easy to improve the performance. In this paper the target discrimination technique, let say, power Delay Profile matching scheme is proposed and the usefulness is investigated by conducting the measurement at 24GHz where the clutter suppression scheme is also considered. As a result, a vehicle target is found to be recognized from multiple vehicles. We have also investigated the effect of bandwidth on the target discrimination capability.
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Power Delay Profile Matching for Vehicle Target Recognition
2009 IEEE 70th Vehicular Technology Conference Fall, 2009Co-Authors: Isamu Matsunami, Youichiro Nakahata, Akihiro KajiwaraAbstract:Radar echo contains unwanted echoes called as clutter, which make it difficult to detect vehicle or obstacle. Especially short-range/wide-angle vehicle radar at 24 GHz suffers from heavy clutter unlike long-range radar at 77 GHz. It is therefore expect to improve the detection performance by suppressing the clutter using a pulse integration and CFAR (Constant False Alarm Rate). However the radar echo should include multiple vehicle targets as well as the clutter, thereby it is not easy to improve the performance. In this paper the target discrimination technique, let say, power Delay Profile matching scheme is proposed and the usefulness is investigated by conducting the measurement at 24 GHz where the clutter suppression scheme is also considered. As a result, a vehicle target is found to be recognized from multiple vehicles. We have also investigated the effect of bandwidth on the target discrimination capability.
Yih-fang Huang - One of the best experts on this subject based on the ideXlab platform.
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Fine timing synchronization using power Delay Profile for OFDM systems
2005 IEEE International Symposium on Circuits and Systems, 2005Co-Authors: Hao Zhou, Yih-fang HuangAbstract:Timing synchronization is more critical in orthogonal frequency division multiplexing (OFDM) systems than in single carrier systems. In this paper, a timing estimation scheme is derived from maximum likelihood estimation (MLE) using power Delay Profile. It is implemented using a Delay locked loop (DLL) to achieve fine timing synchronization for OFDM systems. With this scheme, the mean-square error of symbol timing estimation is decreased by orders of magnitude when compared to the simple peak-finding scheme in multipath fading channels. This scheme also shows higher tracking accuracy for symbol timing drift caused by the sampling clock frequency offset.
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ISCAS (3) - Fine timing synchronization using power Delay Profile for OFDM systems
2005 IEEE International Symposium on Circuits and Systems, 2005Co-Authors: Hao Zhou, Yih-fang HuangAbstract:Timing synchronization is more critical in orthogonal frequency division multiplexing (OFDM) systems than in single carrier systems. In this paper, a timing estimation scheme is derived from maximum likelihood estimation (MLE) using power Delay Profile. It is implemented using a Delay locked loop (DLL) to achieve fine timing synchronization for OFDM systems. With this scheme, the mean-square error of symbol timing estimation is decreased by orders of magnitude when compared to the simple peak-finding scheme in multipath fading channels. This scheme also shows higher tracking accuracy for symbol timing drift caused by the sampling clock frequency offset.
S.s. Ghassemzadeh - One of the best experts on this subject based on the ideXlab platform.
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Comparing Three Models for UWB Indoor Power Delay Profile
2006 40th Annual Conference on Information Sciences and Systems, 2006Co-Authors: L.j. Greenstein, S.s. GhassemzadehAbstract:We compare three approaches for modeling the ultra-wideband (UWB) indoor channel Delay Profile, including the one adopted by the IEEE 802.15.3a Task Group. We do this using a large database we collected, spanning numerous indoor environments. We test the models against this database and against each other by computing certain statistical 'attributes' of the ensemble of channel Delay Profiles, e.g., the probability distribution, across the ensemble, of the root-mean-square (rms) Delay spread. We show that each of the modeling approaches yields reasonable agreement with the database for most or all of the attributes tested, and we discuss the relative merits of the three approaches.
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UWB Delay Profile models for residential and commercial indoor environments
IEEE Transactions on Vehicular Technology, 2005Co-Authors: S.s. Ghassemzadeh, L.j. Greenstein, A. Kavcic, T. Sveinsson, V. TarokhAbstract:We present models for the ultrawideband (UWB) channel Delay Profile in indoor environments, based on the processing of two large sets of measured data. Both measurement sets are for a center frequency of 5 GHz, but the bandwidths are very different-1.25 GHz and 6 GHz. We model both line-of-sight (LOS) and nonline-of-sight (NLOS) paths, and do so for both single-family homes and commercial buildings. Also, we consider both the Profile at a receiver point, which we call the multipath intensity Profile (MIP), and the locally spatially averaged Profile, which we call the power Delay Profile (PDP). For both cases, we find that the Profile for NLOS paths can be modeled as a decaying exponential times a noise-like variation with lognormal statistics and that, for LOS paths, the Profile has the same form plus a strong component at the minimum Delay. The model consists of statistical descriptions of the parameters of these functions, including the effects of transmit-receive (T--R) distance and of variations from building to building. We show simulation results for a few cases to demonstrate that the model accurately predicts key properties of the measured channels, such as the distribution of rms Delay spread.
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UWB indoor Delay Profile model for residential and commercial environments
2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEE Cat. No.03CH37484), 2003Co-Authors: S.s. Ghassemzadeh, L.j. Greenstein, A. Kavcic, T. Sveinsson, V. TarokhAbstract:We present a statistical model for the Delay Profile of ultra-wideband channels in indoor environments. Two kinds of Profiles are defined, namely the multipath intensity Profile (MIP) and the power Delay Profile (PDP). The MIP is the Delay Profile at a point in space, while the PDP is a local spatial average. The model is based on 60,000 complex frequency response measurements from 20 commercial buildings and 20 residential homes, with the transmitter and receiver both in line-of-sight (LOS) and non-line-of-sight (NLS) of each other. Simulations using the PDP model show excellent statistical agreement with the measured data.
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a model for the multipath Delay Profile of fixed wireless channels
IEEE Journal on Selected Areas in Communications, 1999Co-Authors: V Erceg, S.s. Ghassemzadeh, David G Michelson, Lawrence Joel Greenstein, A J Rustako, P B Guerlain, M K Dennison, Robert Stephen Roman, D J Barnickel, S C WangAbstract:This paper deals with the measurement and modeling of multipath Delay on fixed wireless paths at 1.9 GHz in suburban environments. The primary focus is on the Delay Profile, which is the normalized plot of received power versus Delay in response to an RT "impulse." We describe measurement campaigns in the western suburbs of Chicago, IL, and in suburban north-central New Jersey. Our analysis of the data suggests to us that, for directive terminal antennas, the Delay Profile can be modeled as having a "spike-plus-exponential" shape, i.e., a strong return ("spike") at the lowest Delay, plus a set of returns whose mean powers decay exponentially with Delay. This Delay Profile can be characterized by just two parameters (both variable over the terrain), namely, the ratio (K/sub 0/) of the average powers in the "spike" and "exponential" components and the decay time constant (/spl tau//sub 0/) of the "exponential" component. No such simple structure appears to apply for Delay Profiles using omnidirectional antennas. For a directive antenna with a 32/spl deg/ beamwidth, we find that: (1) the statistical correlation between the Profile parameters K/sub 0/ and /spl tau//sub 0/ is negligible; (2) these parameters are relatively insensitive to antenna height and path length; and (3) over each measured region (Illinois and New Jersey), K/sub 0/ and /spl tau//sub 0/ have median values close to 8 dB and just below 0.2 /spl mu/s, respectively. Moreover, we have found simple probability distributions that accurately portray the variability of K/sub 0/ and /spl tau//sub 0/ over the terrain.