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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 [a] 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

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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 [a]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

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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 [a] school of information communication engineering Beijing University of Posts 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

User-perceived e-mail service QoS parameters and measurement

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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 [a] school of information communication engineering Beijing University of Posts 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

Lifetime maximization of cooperative networks with mean channel gain information

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The Journal of China Universities of posts and telecommunications 2009年第4期16卷 98-103页

作者： YANG Chang-qing,WANG Wen-bo,ZHAO Shuang,PENG Mu-gen school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,China [a]school of information and communication engineering beijing university of posts and telecommunications beijing 100876 China

A simple but effective relay-selection and power-allocation scheme is proposed to maximize the lifetime of decode-and-forward （DF） cooperative networks under the constraint that only the mean channel gain information is available at the transmitters. The new scheme takes both channel state information （CSI） and residual energy information （REI） into consideration. To evaluate the performance of the proposed scheme, three typical relay-selection and power-allocation schemes, i.e., maximum residual energy （MRE）, minimum transmit power （MTP） and equal transmit power （ETP） are considered. Simulation results show that the proposed scheme outperforms the MRE and the MTP in lifetime duration and outage probability, while needing much less signal overhead compared with the ETP.

关键词： cooperative commtmication lifetime relay selection power allocation Rayleigh fading

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

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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 [a]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

Valiant load-balancing and regionalized routing scheme

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The Journal of China Universities of posts and telecommunications 2010年第3期17卷 78-84页

作者： YANG Fan , WANG Zhen-kai, CHEN Jian-ya, LIU Yun-jie school of information and communication engineering, beijing university of posts and telecommunications, beijing 100876, China [b] school of information communication engineering Beijing University of Posts telecommunications Beijing 100876 China

Valiant load-balancing （VLB） routing scheme has drawbacks of logical full mesh, intermediate nodes （networks） and single application of topology. To address these, the authors propose a novel routing scheme called regionalized VLB （R-VLB）. Based on ideas of VLB and regionalizing, R-VLB divides the nodes of backbone network into several regions whose topological structure is logical full mesh, and combines shortest-path routing scheme and VLB routing scheme. R-VLB also achieves logical local interconnection, non-central nodes （networks） and a wide range of application of topology. The relevant theoretical analysis and simulation results show that R-VLB achieve good throughput and failure performance close to that of VLB, and it even has better delay performance. R-VLB provides an idea for the application of VLB routing scheme.

关键词： routing scheme VLB topology backbone network

Transmit-reference UWB system based on m-sequence codes

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The Journal of China Universities of posts and telecommunications 2010年第1期17卷 25-31页

作者： ZHAO Lin-li,Lü Tie-jun,QIAO Yong-wei school of information and communication engineering,beijing university of posts and telecommunications,beijing 100876,China [a] school of information communication engineering Beijing University of Posts telecommunications Beijing 100876 China

In this article, a novel transmit-reference （TR） signaling scheme is proposed for ultra-wideband （UWB） system, where by invoking m-sequence codes the reference and data pulses can be transmitted side by side to increase the data rate. This structure enables demodulation with a simple and practical autocorrelation receiver despite existence of severe inter-pulse interference （IPI） To evaluate detection performance of the new designs, closed-form expression for bit error probability （BRP） is theoretically derived and simulation results confirm the analytical results. In addition, the proposed scheme can be extended to M-ary systems to further improve the data rate and power efficiency.

关键词： UWB TR IPI m-sequence M-ary

Radio resource management strategy for VoIP service in TD-HSDPA system

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The Journal of China Universities of posts and telecommunications 2009年第4期16卷 29-33页

作者： HE Da-jiang ,CUI Jie,CHANG Yong-yu,YANG Da-cheng school of communication and information engineering,beijing university of posts and telecommunications,beijing 100876,China [a]school of communication and information engineering beijing university of posts and telecommunications beijing 100876 China

In this article, the performance of a novel radio resource management （RRM） strategy for voice over IP （VoIP） service will be evaluated in low code rate （LCR） time duplex high speed downlink packet access （TD-HSDPA） system. This novel RRM strategy is studied from the aspects of scheduling algorithm and time slot assignment algorithm. As VolP is delay sensitive service, the delay based proportional fair （DBPF） scheduler is proposed in this article. Smart antenna （SA）, which is adopted in LCR TD-HSDPA, can obtain spatial information from the direction of arrival （DOA） estimation. To exploit this spatial information further, a dynamic time slot allocation （DTA） algorithm is introduced to cooperate with the DBPF scheduler. The performance of the round robin （RR）, proportional fair （PF） with the random time slot allocation （RTA） algorithm will be given to demonstrate the benefits of this novel DBPF with DTA RRM strategy. The system level simulation results prove that the performance of this novel RRM strategy is the best of all the RRM strategies.

关键词： RRM smart antenna VolP DBPF DTA HARQ AMC