检索结果-南通市图书馆

Blind channel estimation for multiple antenna OFDM system subject to unknown carrier frequency offset

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2014年第5期25卷 721-727页

作者： Xiaofei Zhang dazhuan xu Department of Electronic Engineering Nanjing University of Aeronautics and Astronautics

The problem of channel estimation for multiple an- tenna orthogonal frequency division multiplexing （OFDM） systems subject to unknown carrier frequency offset （CFO） is addressed. Multiple signal classification （MUSIC）-Iike algorithm, which generally has been used for direction estimation or frequency estimation, is used for channel estimation in multiple antenna OFDM systems. A reduced dimensional （RD）-MUSIC based algorithm for channel estimation is proposed in multiple antenna OFDM systems with unknown CFO. The Cramer-Rao bound （CRB） of channel estimation in multiple antenna OFDM systems with unknown CFO is derived. The proposed algorithm has a superior performance of channel estimation compared with the Capon method and the least squares method.

关键词： channel estimation orthogonal frequency division multiplexing (OFDM) multiple antennas multiple signal classification (MUSIC).

Angle estimation in bistatic MIMO radar using improved reduced dimension Capon algorithm

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2013年第1期24卷 84-89页

作者： Xiaofei Zhang dazhuan xu Electronic Engineering Department Nanjing University of Aeronautics and Astronautics

This paper discusses the problem of direction of departure （DOD） and direction of arrival （DOA） estimation for a bistatic multiple input multiple output （MIMO） radar, and proposes an improved reduced-dimension Capon algorithm therein. Compared with the reduced-dimension Capon algorithm which requires pair matching between the two-dimensional angle estimation, the pro- posed algorithm can obtain automatically paired DOD and DOA estimation without debasing the performance of angle estimation in bistatic MIMO radar. Furthermore, the proposed algorithm has a lower complexity than the reduced-dimension Capon algorithm, and it is suitable for non-uniform linear arrays. The complexity of the proposed algorithm is analyzed and the Cramer-Rao bound （CRB） is also derived. Simulation results verify the usefulness of the proposed algorithm.

关键词： multiple input multiple output (MIMO) radar angle estimation Capon algorithm non-uniform array.

Improved scheme with cooperative diversity based on distributed space-time block coding

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2009年第3期20卷 463-469页

作者： Du Na xu dazhuan Coll. of Information Science & Technology Nanjing Univ. of Aeronautics and Astronautics Nanjing 210016 P. R. China

An improved scheme with cooperative diversity based on distributed space-time block coding （WCD- DSTBC） is proposed, which effectively achieves diversity gains and improves the performance of the system by sharing some single-antenna users＇ antennas to form a virtual antenna array and combining with distributed spacetime block coding （DSTBC） mode. Then the relation between the system BER and the interuser BER for WCDDSTBC scheme is theoretically derived and the closed-form expression of BER for WCD-DSTBC system is obtained. The simulation results show that the proposed WCD-DSTBC scheme achieves distinct gains over the non-cooperative multi-carrier CDMA （MC-CDMA） system. When system BER is le-3 and interuser BER is le-3, about 2.5 dB gain can be gotten. When interuser channel state information （CSI） outgoes the users＇ individual CSI, about 3 dB gain is also achieved.

关键词： multiple input multiple output cooperative diversity distributed space-time block coding multicarrier CDMA.

Two Classes of Quaternary Codes from Z_4-valued Quadratic Forms

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2018年第5期35卷 896-912页

作者： Zhu Xiaoxing xu dazhuan College of Mathematics Nanjing University of Aeronautics and Astronautics College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics

Let R=GR (4,m)be a Galois ring with Teichmuller set T_m and Tr_m be the trace function fromRto Z_*** this paper,two classes of quaternary codes C_1 = {c(a,b):a ∈R,b ∈ T_(m/2)},where c(a,b)=(Tr_m(ax)+Tr_(m/2)(2 bx^(2 m/2 +1)))_(x∈T_m),and C_2= {c(a,b):a ∈ R,b ∈ T_m}, where c(a,b)=(Tr_m(ax+2 bx^(2 k+1)))_(x∈T_m),and m/gcd(m,k)is even,are investigated,*** Lee weight distributions,Hamming weight distributions and complete weight distributions of the codes are completely given.

关键词： Galois ring quaternary code Hamming weight quadratic form Lee weight

Linear Codes with Two Weights or Three Weights from Two Types of Quadratic forms

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2017年第1期34卷 62-71页

作者： Zhu Xiaoxing xu dazhuan Department of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China College of Electronic and Information Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

Let F_qbe afinite field with q=pmelements,where pis an odd prime and mis apositive ***,let D_0={(x_1,x_2)∈F_q^2\{(0,0)}:Tr(x_1^(pk1+1)+x_2^(pk2+1))=c},where c∈F_q,Tr is the trace function fromFF_qtoFpand m/(m,k_1)is odd,m/(m,k_2)is *** ap-ary linear code C_D =c(a_1,a_2):(a_1,a_2)∈F_q^2},where c(a_1,a_2)=(Tr(a_1x_1+a_2x_2))_((x1,x2)∈D).At most three-weight distributions of two classes of linear codes are settled.

关键词： linear codes weight distribution Gauss sum Weil sum

The design and analysis of unequal error protection fountain coding for multiple source networks over binary erasure channels

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2014年第8期57卷 9-17页

作者： SHAO HanQin xu dazhuan ZHANG XiaoFei College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics

A novel network model of multiple source fountain coding is developed and a novel class of generic multiple source fountain codes with unequal error protection(UEP)property is *** And–Or tree analysis technique is generalized to analyze the asymptotic performance of the proposed codes and a joint optimization method employing both linear and nonlinear programs is developed to optimize the degree ***,we propose three basic methods to achieve UEP property and the performance of each method is *** employ these analytical results and optimization method to design and discuss several UEP codes with two and four sources for different application *** results verify that the proposed codes can be applied to the networks with any number of sources and can provide strong UEP property in various ways based on the proposed three basic methods.

关键词： asymptotic analysis fountain codes binary erasure channels network coding linear program nonlinear program unequal error protection multiple source networks

A simplified bit metric calculation method for high-order PSK

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2013年第7期56卷 109-117页

作者： WANG Lei xu dazhuan ZHANG XiaoFei College of Information Science and Technology Nanjing University of Aeronautics and Astronautics

This paper proposes a simplified bit metric calculation method for high-order PSK signal with Gray-mapping. This method calculates the bit metric recursively by the symmetry of Gray code. Analysis and simulation results show that the proposed method can significantly reduce the computational complexity and maintain similar performance compared to ML and Max-Log bit metric. Additionally, this method generates bit metrics of PSK signals with different modulation order in the same way, so it can be applied to adaptive modulation system.

关键词： phase shift keying high order modulation bit metric soft demodulation

BLIND SIGNAL SEPARATION OF LINEAR MIXTURE USING TRILINEAR DECOMPOSITION

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Electronics(China) 2009年第5期26卷 608-613页

作者： Zhang Xiaofei xu dazhuan Department of Electronic Engineering Nanjing University of Aeronautics ＆ Astronautics Nanjing 210016 China

This paper introduces a new source separation technique exploiting the time coherence of the source signals. The proposed approach relies only on stationary second order statistics. Blind Signal Separation (BSS) method using trilinear decomposition is proposed in this paper. Simulation results reveal that our proposed algorithm has the better blind signal separation performance than joint diagonalization method. Our proposed algorithm does not require whitening processing. Moreover, our proposed algorithm works well in the underdetermined condition, where the number of sources exceeds than the number of sensors.

关键词： Blind Signal Separation (BSS) Second order statistics Trilinear decomposition

MULTI-INVARIANCE ESPRIT-LIKE ALGORITHMS FOR COHERENT DOA ESTIMATION

在线全文

学校读者我要写书评

暂无评论

Journal of Electronics(China) 2010年第1期27卷 24-28页

作者： Zhang Xiaofei xu dazhuan Department of Electronic Engineering Nanjing University of Aeronautics ＆ Astronautics Nanjing 210016 China

Estimation of Signal Parameters via Rotational Invariance Technique(ESPRIT) algorithm can estimate Direction-Of-Arrival(DOA) of coherent signal,but its performance can not reach full *** reconstruct the received signal to form data model with multi-invariance property,and multi-invariance ESPRIT algorithm for coherent DOA estimation is proposed in this *** proposed algorithm can resolve the DOAs of coherent signals and performs better in DOA estimation than that of ESPRIT-like ***,it identifies more DOAs than ESPRIT-like *** simulation results demonstrate its validity.

关键词： Coherent signals Direction-Of-Arrival(DOA) estimation Multi-invariance Estimation of Signal Parameters via Rotational Invariance Technique(ESPRIT)