检索结果-南通市图书馆

Error exponents for two-hop Gaussian multiple source-destination relay channels

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) 2012年第2期55卷 348-359页

作者： DENG PanLiang1,3,LIU YuanAn1,3,XIE Gang2,3,WANG XiaoYu1,3,TANG BiHua1,3 & SUN JianFeng1,3 1school of Electronic engineering,beijing university of posts and telecommunications,beijing 100876,china 2school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,china 3Key Laboratory of Universal Wireless communication,Ministry of Education,beijing 100876,china school of Electronic engineering Beijing University of Posts and Telecommunications Beijing China Key Laboratory of Universal Wireless communication Ministry of Education Beijing China school of information and communication engineering Beijing University of Posts and Telecommunications Beijing China

We investigate the two-hop multiple source-destination relay channels using the rate splitting trans-mission scheme where each source can split its message into private and public *** determine the system error probability via integrated exponent function under amplify-and-forward(AF)and decode-and-forward(DF)relay *** most significant difference between AF and DF system error probability evaluations lies in a minimized cut-set bound of transmission rate under the DF *** are many cases among transmission rate intervals for different system parameters(*** power)and it is extremely complex to derive the system error probability for the DF *** obtain a relatively simple result,which unifies various cases by a few *** results show that the system error probability decreases with the increase of the public ***,in order to draw deep insight into the reliability requirement of each source node in this network,we provide the error exponent region(EER)for different source nodes to show the trade-off of error probability among source nodes.

关键词： error exponent error exponent region rate splitting multiple source-destination relay channel

AN EFFICIENT MOTION ESTIMATION ALGORITHM FOR H.264/AVC H.264/AVC

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

AN EFFICIENT MOTION ESTIMATION ALGORITHM FOR H.264/AVC H.264...

Novel limited feedback scheme under the MIMO broadcast system

中国通信学会第六届学术年会

作者： Guo Yanjie~1,Liu Ruifang~2 (1 school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,china 2 school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,china)

Motion estimation plays an important role in the video compression standard,such as H.263,MPEG-2/4 and *** search(FS) is the most common and simple motion estimation algorithm,but owing to the FS algorithm resulting in huge computational complexity,so many fast motion estimation algorithms have been proposed instead of *** the paper,we discuss UMHexagonS algorithm, then we propose a fast ME algorithm based on *** simulation results show that proposed algorithm maintains an unnoticeable quality loss in terms of PSNR on average compared to FS and UMHexagonS but reduces motion estimation time.

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

The Journal of china Universities of posts and telecommunications 2009年第6期16卷 11-16页

作者： CHENG Tie-zheng,YUAN Chao-wei school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,china school of information and communication engineering Beijing University of Posts and Telecommunications Beijing 100876 China

By deducing the distribution of the normalized channel covariance matrix,a novel limited feedback scheme is proposed under multiple users（MU） multiple-input multiple-output（MIMO） broadcast channel（BC） *** proposed scheme has advantages in three ***,it has no constraints on the number of users or ***,each user＇s feedback bits are independent of the number of receiving ***,the proposed scheme avoids the storage of large-size codebook on the *** results show that the performance of the proposed scheme is close to the perfect channel state information（CSI） case and it just needs a small number of feedback bits.

关键词： MIMO broadcast channel limited feedback normalized channel covariance

Novel THP algorithms with minimum BER criterion for MIMO broadcast communications

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of posts and telecommunications 2009年第4期16卷 71-77页

作者： YUN Xiang,L Tie-jun school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,china school of information and communication engineering Beijing University of Posts and Telecommunications Beijing 100876 China

In this article, two novel Tomlinson-Harashima precoding （THP） algorithms are proposed at the downlink broadcast channel of multi-user multiple-input multiple-output （MIMO） systems. The optimality criterion is the minimization of the bit error rate （BER） at the receiver with a constraint on the overall transmitted power. In these algorithms, transmit power allocation （TPA） matrix is introduced to the traditional THP algorithms as part of the precoding matrix. This leads to a power loading operation based on substreams signal to interference-plus-noise ratio （SINR） and results in improvement of the error rate performance compared with traditional THP algorithms. When the precoding loss factor is considered, further performance improvement is achieved by the enhanced algorithm.

关键词： MIMO system THP minimum bit-error rate (MBER) broadcast communication

Location based spectrum sensing performance analysis over fading channels in cognitive radio networks

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of posts and telecommunications 2010年第5期17卷 26-31页

作者： YAO Hai-peng,ZHOU Zheng,SUN Xuan,LI Bin school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,china school of information and communication engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This paper analyzes the spectrum sensing performance over fading channel,in which a licensee and multiple unlicensed users coexist and operate in the licensed channel in a local *** overall average probabilities of detection and false alarm by jointly taking the fading and the locations of all secondary users into account are derived,and a statistical model of cumulate interference is *** on the cumulate interference,a closed-form expression of outage probability at the primary user’s receiver according to a specific distribution of the fading is ***,the sensing parameters so as to minimize the total spectrum sensing error and maximize the average opportunistic throughput are *** is noted that the overall average performance analysis and results here enable to benchmark the design of specific spectrum sensing algorithms.

关键词： spectrum sensing cognitive radio cumulate interference outage probability

Synchronization of MIMO OFDM systems by perfect complete generalized complementary orthogonal loosely synchronous code groups

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of posts and telecommunications 2009年第2期16卷 1-7页

作者： WANG Jian YANG Xun LI Dao-ben school of information engineering,beijing university of posts and telecommunications,beijing 100876,china school of information engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This article proposes a time/frequency synchronization algorithm in the multiple input multiple output （MIMO） systems, in which the perfect complete generalized complementary orthogonal loosely synchronous code groups are used as the synchronization sequence. The synchronization algorithm is divided into four stages： 1） synchronization in time domain by signal autocorrelation; 2） synchronization in frequency domain by fast Fourier transform （FFT）; 3） multipath dissociation using coherent detection and fine time synchronization; 4） fine frequency offset estimation by phase rotation. As per the perfect complete generalized complementary orthogonal loosely synchronous code groups, the cross-correlation and out-of-phase auto-correlation for any relative shift between any two codes is always zero. This ideal property makes the time/frequency synchronization algorithm simple and efficient. The simulation results show that even in the multipath fast fading channel with low signal noise ratio （SNR）, the MIMO system can get synchronized both in the time domain and frequency domain with high stability and reliability.

关键词： MIMO OFDM synchronization complementary orthogonal code loosely synchronous (LS) code

User-perceived e-mail service QoS parameters and measurement

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of posts and telecommunications 2010年第3期17卷 85-90页

作者： LI Yong-zhi , LIU Feng, LEI Zhen-ming, CHEN Ling school of information and communication engineering, beijing university of posts and telecommunications, beijing 100876, china school of information and communication engineering Beijing University of Posts and Telecommunications Beijing 100876 China

A group of quality of service （QoS） parameters of electronic mail （e-mail） traffic are proposed from users＇ perspective. These parameters cover three fields： delay, throughput and usability. Concept and algorithm of each parameter are presented and its effect on user perceptions is described. In order to evaluate the effectiveness of these parameters, an active measurement system is implemented. Measured results show that the group of QoS parameters we proposed can be used to get a comprehensive view of user-perceived e-mail service QoS.

关键词： user perceptions e-mail service QoS active measurement

QoS-guaranteed multi-relay selection and power allocation optimization in cooperative systems

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of posts and telecommunications 2010年第6期17卷 25-31页

作者： CHEN Dan,JI Hong,LI Xi,LI Yi College of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,china College of information and communication engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This paper investigates the relay selection and power allocation problem in multi-user based cooperative networks,where intermediate relay nodes help source forward information to destination using decode-and-forward （DF） relaying protocol. Specifically,we propose a novel multi-relay nodes selection strategy taking both instantaneous channel state information （I-CSI） and residual energy into consideration,by which ＇emergence＇ diversity gain can be achieved and the imbalance of resource utilization can be overcome. Besides,using Largangian dual-primal decomposition and subgradient projection approach,an optimal power allocation algorithm at source and cooperative relay nodes is presented with the constraints of each user＇s individual quality of service （QoS） requirements and system total transmit power. Theoretical analysis and simulation results demonstrate that the proposed scheme can significantly improve energy efficiency,while guaranteeing a good balance between achievable data rate and average network lifetime with relatively low implementation complexity.

关键词： cooperative diversity relay selection resource allocation Lagrangian dual-primal decomposition subgradient projection

Construction of LDPC codes over GF(q) with modified progressive edge growth

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of posts and telecommunications 2009年第5期16卷 103-106,113页

作者： CHEN Xin , MEN Ai-dong, YANG Bo, QUAN Zi-yi school of information and communication engineering, beijing university of posts and telecommunications, beijing 100876, china school of information and communication engineering Beijing University of Posts and Telecommunications Beijing 100876 China

A parity check matrix construction method for constructing a low-density parity-check （LDPC） codes over GF（q）（q〉2） based on the modified progressive edge growth （PEG） algorithm is introduced. First, the nonzero locations of the parity check matrix are selected using the PEG algorithm. Then the nonzero elements are defined by avoiding the definition of subcode. A proof is given to show the good minimum distance property of constructed GF（q）-LDPC codes. Simulations are also presented to illustrate the good error performance of the designed codes.

关键词： LDPC codes over GF(q) progressive edge growth large minimum distance