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Search Results: 1 - 10 of 74526 matches for " Liang Qing-lin "
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A Reduced Complexity Timing Tracking Scheme for Multi-Carrier CDMA Signals Based on Samples Selecting and Vector Rotation

Luo Wu,Shen Chang,Liang Qing-lin,
罗 武
,申 畅,梁庆林

电子与信息学报 , 2006,
Abstract: A reduced-complexity all-digital timing tracking scheme suited for multi-carrier CDMA signals is proposed and studied. Based on samples selecting and vector rotation of correlation output vector at only on time channel, timing error detection statistics are approximately acquired and timing adjustment are carried out. Theoretical and numerical results show that the new scheme has an improved performance and remarkable complexity simplicity as compared with the classical digital delay-locked loop.
A Novel Method for Calculating the DFE Coefficients Based on Quadratic Programming

Bai Dong,Liu Hong,Liang Qing-lin,

电子与信息学报 , 2005,
Abstract: Decision Feedback Equalizer (DFE) is widely used in practice, which is usually designed according to Minimum Mean Square Error (MMSE) criterion. A novel method is derived for calculating the DFE coefficients based on quadratic programming. Simulations show that the new method is equal to the traditional one.
A New Beamformer for Coherent Signals

Shi Shuang-ning,Shang Yong,Liang Qing-lin,Liang Bin,
,尚 勇,梁庆林,梁 斌

电子与信息学报 , 2008,
Abstract: In the process of the beamforming for the coherent signals, because of the estimation error of the coherent signal energy and the estimation error of covariance matrix R, and perturbation error on the steering vector, the output SINR of beamformer drops badly. In this paper a new beamformer is presented based on the LS shaping from quantum signal processing. As a robust beamformer it shows the good performance in the circumstance discussed above. Analysis and simulations are given to prove the efficiency and validity of the new beamformer.
Finite Length Analysis of Fountain Codes Based on Stopping Set

Lin Guang-rong Yi Na Dong Ming-ke Liang Qing-lin,

电子与信息学报 , 2008,
Abstract: Digital Fountain is a packet oriented FEC technology for erasure channels. And the performance of fountain codes is limited by the distribution of stopping sets. In the paper, a pair of bounds was proposed to estimate the decoding failure probability of finite length fountain codes. And a search algorithm of low complexity was presented to get the stopping set distribution. The comparisons show that the upper and lower bounds are very close to the simulation results.
Fast PDA Multiuser-Detection Algorithm in SDMA System

Wang Bing,Zhao Yu-ping,Zou Li,Liang Qing-lin,

电子与信息学报 , 2004,
Abstract: Compared with optimal maximum-likelihood multiuser detection algorithm (MUD) in Space Division Multiuser Access (SDMA) system, probabilistic data association (PDA) algorithm is a near-optimal MUD with low complexity. This paper analyzes the relation between error judging and estimated likely-probability in the 1st iteration of PDA, then proposed the fast PDA which correcting the judging output in the 1st iteration of PDA with Euclidean distance factor. Fast PDA reduces complexity of PDA through eliminating its iterations. Simulation results show that BER of fast PDA is very close to PDA with iterations.
A Novel PN Code Timing Tracking Loop for DS/CDMA Systems

Luo Wu,Wang Wei-ping,Dong Ming-ke,Liang Qing-lin,
罗 武

电子与信息学报 , 2006,
Abstract: In this paper a novel non-coherent all-digital timing tracking scheme is described and analyzed for chip timing synchronization in direct sequence spread spectrum systems. Results of the theoretical analysis and computer simulations show that the scheme improves tracking performance as compared with the traditional delay-locked loop (DLL) in an AWGN environment. Also, the new scheme enhances the hardware simplification with respect to other traditional non-coherent schemes.
Multiple Sub-intervals Integration Period Optimization for Noncoherent UWB-PPM Receiver in Sparse Multipath Channels

Wu Jian-jun,Liang Qing-lin,Xiang Hai-ge,

电子与信息学报 , 2007,
Abstract: The non-coherent receiver is attractive for UWB system due to its implementation simplicity,which, however,is also accompanied with its performance degradation.As an effective optimization method,the integration interval selection is usually performed under the single-interval constraint among existed literatures, to the best knowledge of the authors,which not only results in large searching computation complexity but also could not reach the so-called optimal performance.In this paper,a multiple sub-intervals optimization method is proposed based on the derivation of closed-form BER performance expression of the non-coherent receiver and its corresponding modification under small time-bandwidth product condition.It is shown from the numerical results that the BER performance of the multiple sub-intervals optimization method is obviously superior to the single-interval method,especially in those sparse multipath channels.
Doubly Selective Channel Estimation Based on Ideal Autocorrelation Sequence

Liu Ying-nan,Jiang Wei,Liang Qing-lin,Yao Chun-guang,
,蒋 伟①,姚春光②,梁庆林①

电子与信息学报 , 2008,
Abstract: High data rates and high mobility-induced Doppler shifts introduce time- and frequency-selectivity in wireless links. Recently, doubly selective channel estimation has attracted much attention. In this paper, using a basis expansion channel model, a scheme based on ideal autocorrelation sequence is proposed for the estimation of doubly selective channel parameters. The training sequences have constant modulus so that large peak-to-average ratio problem can be avoided. It has been shown that the employment of this optimal pilot sequence can minimize Mean-Square Error (MSE) of the channel estimation. Simulation results demonstrate that the peak-to-average ratio of the proposed scheme is considerably improved compared to the existing zero-padding scheme for the same MSE performance.
Optimization of Pre-filter Passband Width for Noncoherent UWB-PPM Receiver

Wu Jian-jun,Liang Qing-lin,Xiang Hai-ge,

电子与信息学报 , 2007,
Abstract: The noncoherent receiver is attractive for UWB system implementation in lower data rate applications due to its simplicity for implementation,which,however,is accompanied with the performance degradation.There are some factors that affect the performance of noncoherent receiver,among which is the selection of the pre-filter passband width.In this paper,the inter-path interference incurred by the pre-filter is analyzed numerically and statistically,and the optimal passband widths are analyzed as well based on the derivation of closed-form BER performance expression.It is shown that,the impact of IPI due to the pre-filter is insignificant to noncoherent receiver,and there exist different optimal pre-filter passband widths for different channels and input SNRs.However,the-3dB/-10dB bandwidth of the Gaussian pulse,as well as 2 times of the pulse width reciprocal,could be treated as a suboptimal filter bandwidth,which would only result in a lightly performance degradation.
Least Square Estimation of Doubly Selective Wireless Fading Channels

Liu Ying-nan Jiang Wei Ren Shu-bo Liang Qing-lin,

电子与信息学报 , 2008,
Abstract: High data rates and high mobility induced Doppler shifts introduce time and frequency selectivity in wireless links. The quality of channel acquisition has a major impact on the overall system performance. In this paper, relying on a basis expansion channel model, a scheme is proposed for estimating doubly selective channel parameters . The receiver does not have to know the statistic information of the channels and will not estimate the power of noise in advance, and has low-complexity. Along with the estimation scheme, the optimal pilot sequence is derived based on minimizing mean-square error of the channel estimation. Simulation results demonstrate the performance of the proposed scheme is better than existing scheme for a range of SNR, where a frequency- selective channel is randomly generated with different Doppler spreads via Jakes’ model.
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