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Search Results: 1 - 10 of 5135 matches for " Liao Guisheng "
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Application of Array Processing Techniques in Multibaseline Insar for High-Resolution Dem Reconstruction
Zhijie Mao;Guisheng Liao
PIER M , 2008, DOI: 10.2528/PIERM08101505
Abstract: This work is concerned with generating the digital elevation models (DEMs) from the SAR images of the region of interest using multiple sensor arrays that are fixed on the distributed satellites. We present an exact estimate of the unwrapped phase and the relationship between the unwrapped phase and the terrain height. The optimum scheme that jointly processes the signals from all sensors is based on the model of the multibaseline joint block vector. The method can simultaneously coregister the SAR images, phase unwrapping and DEM generation in the presence of the large coregistration errors. The performance of our approach is verified by a series of simulation experiments based on the distributed sensor arrays.
Concatenated Space-Time Block Coding with Asymmetric MPSK TCM for Fast Fading Channels
Ao Ju,Ma Chunbo,Liao Guisheng
Information Technology Journal , 2008,
Abstract: The field of concatenated space-time block coding (inner) with trellis coded modulation (outer) has recently attracted interest as a means of jointly considering the error correction coding gain and diversity gain possible without bandwidth expansion and power expansion over fading channels. In this research, a concatenated Space-Time Block Coding (STBC)with asymmetric MPSK TCM scheme, based on the design criteria for constructing concatenated space-time block coding with TCM for fast Rayleigh fading channels, is presented by introducing the new optimal signal point assignment. Using parameter comparison and simulation results, the proposed concatenated STBC with asymmetric MPSK TCM is shown to have better coding gain than traditional concatenated STBC with TCM under the same spectral efficiency, decoding complexity.
Joint Frequency Ambiguity Resolution and Accurate Timing Estimation in OFDM Systems with Multipath Fading
Li Jun,Liao Guisheng,Ouyang Shan
EURASIP Journal on Wireless Communications and Networking , 2006,
Abstract: A serious disadvantage of orthogonal frequency-division multiplexing (OFDM) is its sensitivity to carrier frequency offset (CFO) and timing offset (TO). For many low-complexity algorithms, the estimation ambiguity exists when the CFO is greater than one or two subcarrier spacing, and the estimated TO is also prone to exceeding the ISI-free interval within the cyclic prefix (CP). This paper presents a method for joint CFO ambiguity resolution and accurate TO estimation in multipath fading. Maximum-likelihood (ML) principle is employed and only one pilot symbol is needed. Frequency ambiguity is resolved and accurate TO can be obtained simultaneously by using the fast Fourier transform (FFT) and one-dimensional (1D) search. Both known and unknown channel order cases are considered. Computer simulations show that the proposed algorithm outperforms some others in the multipath fading channels.
Joint Frequency Ambiguity Resolution and Accurate Timing Estimation in OFDM Systems with Multipath Fading
Jun Li,Guisheng Liao,Shan Ouyang
EURASIP Journal on Wireless Communications and Networking , 2006,
Abstract: A serious disadvantage of orthogonal frequency-division multiplexing (OFDM) is its sensitivity to carrier frequency offset (CFO) and timing offset (TO). For many low-complexity algorithms, the estimation ambiguity exists when the CFO is greater than one or two subcarrier spacing, and the estimated TO is also prone to exceeding the ISI-free interval within the cyclic prefix (CP). This paper presents a method for joint CFO ambiguity resolution and accurate TO estimation in multipath fading. Maximum-likelihood (ML) principle is employed and only one pilot symbol is needed. Frequency ambiguity is resolved and accurate TO can be obtained simultaneously by using the fast Fourier transform (FFT) and one-dimensional (1D) search. Both known and unknown channel order cases are considered. Computer simulations show that the proposed algorithm outperforms some others in the multipath fading channels.
MIMO-OFDM Channel Estimation in the Presence of Carrier Frequency Offset
Jun Li,Guisheng Liao,Qinghua Guo
EURASIP Journal on Advances in Signal Processing , 2005, DOI: 10.1155/asp.2005.525
Abstract: A multiple-input multiple-output (MIMO) wireless communication system with orthogonal frequency division multiplexing (OFDM) is expected to be a promising scheme. However, the estimation of the carrier frequency offset (CFO) and the channel parameters is a great challenging task. In this paper, a maximum-likelihood- (ML-) based algorithm is proposed to jointly estimate the frequency-selective channels and the CFO in MIMO-OFDM by using a block-type pilot. The proposed algorithm is capable of dealing with the CFO range nearly ±1/2 useful OFDM signal bandwidth. Furthermore, the cases with timing error and unknown channel order are discussed. The Cram r-Rao bound (CRB) for the problem is developed to evaluate the performance of the algorithm. Computer simulations show that the proposed algorithm can exploit the gain from multiantenna to improve effectively the estimation performance and achieve the CRB in high signal-to-noise ratio (SNR).
Corrections to ¢ € Multitarget Identification and Localization Using Bistatic MIMO Radar Systems ¢ €
Haidong Yan,Jun Li,Guisheng Liao
EURASIP Journal on Advances in Signal Processing , 2008, DOI: 10.1155/2008/973932
Abstract:
Multitarget Identification and Localization Using Bistatic MIMO Radar Systems
Haidong Yan,Jun Li,Guisheng Liao
EURASIP Journal on Advances in Signal Processing , 2007, DOI: 10.1155/2008/283483
Abstract: A scheme for multitarget identification and localization using bistatic MIMO radar systems is proposed. Multitarget can be distinguished by Capon method, as well as the targets angles with respect to transmitter and receiver can be synthesized using the received signals. Thus, the locations of the multiple targets are obtained and spatial synchronization problem in traditional bistatic radars is avoided. The maximum number of targets that can be uniquely identified by proposed method is also analyzed. It is indicated that the product of the numbers of receive and transmit elements minus-one targets can be identified by exploiting the fluctuating of the radar cross section (RCS) of the targets. Cramer-Rao bounds (CRB) are derived to obtain more insights of this scheme. Simulation results demonstrate the performances of the proposed method using Swerling II target model in various scenarios.
A Modified Fast Approximated Power Iteration Subspace Tracking Method for Space-Time Adaptive Processing
Yang Zhiwei,He Shun,Liao Guisheng,Ouyang Shan
Journal of Electrical and Computer Engineering , 2010, DOI: 10.1155/2010/973718
Abstract: We propose a subspace-tracking-based space-time adaptive processing technique for airborne radar applications. By applying a modified approximated power iteration subspace tracing algorithm, the principal subspace in which the clutter-plus-interference reside is estimated. Therefore, the moving targets are detected by projecting the data on the minor subspace which is orthogonal to the principal subspace. The proposed approach overcomes the shortcomings of the existing methods and has satisfactory performance. Simulation results confirm that the performance improvement is achieved at very small secondary sample support, a feature that is particularly attractive for applications in heterogeneous environments.
Self-calibration method without joint iteration for distributed small satellite SAR systems
Qing Xu, Guisheng Liao, Aifei Liu and Juan Zhang
EURASIP Journal on Advances in Signal Processing , 2013, DOI: 10.1186/1687-6180-2013-31
Abstract: The performance of distributed small satellite synthetic aperture radar systems degrades significantly due to the unavoidable array errors, including gain, phase, and position errors, in real operating scenarios. In the conventional method proposed in (IEEE T Aero. Elec. Sys. 42:436--451, 2006), the spectrum components within one Doppler bin are considered as calibration sources. However, it is found in this article that the gain error estimation and the position error estimation in the conventional method can interact with each other. The conventional method may converge to suboptimal solutions in large position errors since it requires the joint iteration between gain-phase error estimation and position error estimation. In addition, it is also found that phase errors can be estimated well regardless of position errors when the zero Doppler bin is chosen. In this article, we propose a method obtained by modifying the conventional one, based on these two observations. In this modified method, gain errors are firstly estimated and compensated, which eliminates the interaction between gain error estimation and position error estimation. Then, by using the zero Doppler bin data, the phase error estimation can be performed well independent of position errors. Finally, position errors are estimated based on the Taylor-series expansion. Meanwhile, the joint iteration between gain-phase error estimation and position error estimation is not required. Therefore, the problem of suboptimal convergence, which occurs in the conventional method, can be avoided with low computational method. The modified method has merits of faster convergence and lower estimation error compared to the conventional one. Theoretical analysis and computer simulation results verified the effectiveness of the modified method.
BLIND ESTIMATES OF DOA-DOPPLER FREQUENY WITH UNKNOWN ARRAY MANIFOLD
未知阵列流形条件下波达方向一多普勒频率盲估计方法

Liao Guisheng,Bao Zheng,
廖桂生
,保铮

电子与信息学报 , 1997,
Abstract: A novel blind estimate of direction of arrival (DOA) and Doppler frequency with unknown array manifold is proposed, employing Doppler frequency difference between a successive pulses as rotational parameter. The effectiveness of the new method is confirmed by computer simulations. Compared with the existing two-dimensional frequency estimates, the computation load of the proposed method can be saved greatly.
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