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International Conference on Cyberspace Technology (CCT 2013)

作者： Haijing Liu Tiejun Lv Yueming Lu Key Laboratory of Trustworthy Distributed Computing and Service Ministry of Education School of Information and Communication Engineering Beijing University of Posts and Telecommunications China 100876

ISBN: (纸本)9781632660015

In this paper, we propose a codebook-based hybrid opportunistic interference alignment (OIA) in a three-cell MIMO downlink system. Rather than transmitting data by only one beamforming vector set in the conventional OIA, the transmitters select a preferred transmit beamforming vector set from a codebook in the proposed scheme. Hence, more selection diversity is developed compared to the conventional OIA approaches, The sum rate performance increases as the size of the codebook grows. Furthermore, a hybrid criterion of MAX-SNR and OIA is put forward which enhances the system performance at both high and low SNR. Monte-Carlo simulations illustrate that the proposed scheme provides a significant improvement in terms of sum rates with a slight complexity increase

关键词： MAX-SNR Opportunistic Interference Alignment hybrid criterion codebook Transmitting Data System performance HYBRID Hybrid electric vehicles Beamforming sums Alignment low SNR

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The massive MU-MIMO system with optimal number of users through linear precoders

The massive MU-MIMO system with optimal number of users thro...

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International Conference on Cyberspace Technology (CCT 2013)

作者： Ou Bai Tiejun Lv Haijing Liu Yuennng Lu Key Laboratory of Trustworthy Distributed Computing and Service Ministry of Education School of Information and Communication Engineering Beijing University of Posts and Telecommunications China 100876

ISBN: (纸本)9781632660015

In this paper, the downlink (DL) of the multiuser multiple-input multiple-output (MU-MIMO) system is investigated, where channel estimation and large-scale fading are taken into consideration and the number of antennas M at the base station (BS) is extremely large. We calculate the asymptotic sum rate of singular value decomposition (SVD)-based precoder and regularized zero-forcing (RZF) precoder. The optimal number of served users is taken into account. The result shows that M should be more than the product of the number of users and the number of antennas at each user. Based on the optimal number, we propose a convenient data stream allocation strategy aiming to improve the system sum rate, meanwhile maintaining the number of simultaneously served users. Numerical simulations reveal that our approximations are appropriate for the large-scale MU-MIMO system and the proposed data stream allocation can provide significant improvement in sum-rate performance.

关键词： RZF SVD massive MIMO optimal number optimum number Singular value decomposition Swine vesicular disease Consumers multiple input multiple output systems ANTENNA data flow

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Exact analysis of transmit/receive zero-forcing based MIMO af two-way relaying when relay has two antennas

Exact analysis of transmit/receive zero-forcing based MIMO a...

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International Conference on Cyberspace Technology (CCT 2013)

作者： Rongsheng Li Tiejun Lv Yueming Lu Key Laboratory of Trustworthy Distributed Computing and Service Ministry of Education School of Information and Communication Engineering Beijing University of Posts and Telecommunications China 100876

ISBN: (纸本)9781632660015

In this paper, the performance of joint transmit/receive zero-forcing (ZF) is analyzed for multiple-input multiple-out (MIMO) amplify-and-forward (AF) two-way relay network when the relay has two antennas. The performance is studied by deriving exact expressions of the overall outage probability and the diversity order under the uncorrected Rayleigh fading channel and relay-correlated Rayleigh fading channel as well. Analysis and simulation results indicate that, compared to uncorrected Rayleigh fading, spatial correlation at the relay deteriorates the performance of the system greatly, but does not affect the diversity order of the system.

关键词： MIMO Outage Probability Two-Way Relaying Zero-Forcing multiple input multiple output systems relay Bidirectional Raleigh fading channels ANTENNA Instruction repertory Relay networks relaying Exact

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Decision feedback threshold selection for UWB TOA estimation with energy detection receiver

Decision feedback threshold selection for UWB TOA estimation...

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International Conference on Cyberspace Technology (CCT 2013)

作者： Hong Cai Tiejun Lv Yueming Lu Key Laboratory of Trustworthy Distributed Computing and Service Ministry of Education School of Information and Communication Engineering Beijing University of Posts and Telecommunications China 100876

ISBN: (纸本)9781632660015

The energy detection receiver is a practical solution for time-of-arrival (TOA) estimation in ultra-wide bandwidth (UWB) ranging with its sub-Nyquist sampling rate. However, the threshold selection under harsh environments is a challenging problem. In this paper, a decision feedback criterion that determines the threshold value is proposed, with which the probability of early false detection can be reduced and the missed detection can be avoided. In this criterion, the threshold is determined by the noise level, and can be adjusted iteratively according to the feedback of the threshold comparing result with a purpose of avoiding missed detection. As a result, the estimation accuracy of the TOA is improved. Simulation results show that significant performance improvement can be derived with the proposed method.

关键词： Energy detection TOA UWB feedback threshold selection

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Multiuser MIMO Using Block Diagonalization: How Many Users Should be Served?

Multiuser MIMO Using Block Diagonalization: How Many Users S...

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IEEE Global Communications Conference

作者： Wei Ding Tiejun Lv Key Laboratory of Trustworthy Distributed Computing and Service Ministry of Education School of Information and Communication Engineering Beijing University of Posts and Telecommunications China 100876|c|

ISBN: (纸本)9781479913510

In this paper, an undesired fact for multiuser (MU) MIMO (MU-MIMO) systems using block diagonalization is presented, i.e., the increment of user number (K) results in the degradation of sum rate. This fact is caused by the opposition between two main factors determining the sum rate, namely, MU gain and transmit diversity. The MU gain guarantees a high order of degrees of freedom (DoFs) on system level but decreases the rate per user, while, for the transmit diversity, it is exactly opposite. Therefore, the tradeoff between the two factors is established to quantify how the two factors impact on the sum rate. Based on the tradeoff, the optimal K that maximizes the sum rate is further obtained. Additionally, it is pointed out that the sum rate can be improved substantially by only adding a few antennas at the base station when the system is fully loaded. The derivations are under large-scale system assumption, and being implemented on different precoders. Numerical simulations verify the tightness and accuracy of our asymptotic results for both large-scale and conventional systems.

关键词： MU-MIMO derivations tightness TIGHTNESS diversity reception sums multiple input multiple output systems diagonalization derivation tradeoffs higher-order system level large sizes

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An improved DFT-based channel estimation method for OFDM system

An improved DFT-based channel estimation method for OFDM sys...

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International Conference on Cyberspace Technology (CCT 2013)

作者： Xingxing Li Xiaojun Jing Songlin Sun Hai Huang Yueming Lu Key Laboratory of Trustworthy Distributed Computing and Service (BUPT) Ministry of Education School of Information and Communication Engineering Beijing University of Posts and Telecommunications 100876 China

In the OFDM system, channel estimation is significant in that it affects the reliability of coherent detection at the receiver side. DFT-based channel estimation method is suitable for sparse channel estimation due to sparsity means low computational complexity. Combined with exponential smoothing, an improved DFT-Based channel estimation method is proposed in order to suppress noise. The noise suppression capacity of exponential smoothing is analyzed in theory. Simulation results indicate that the improved method is superior to DFT-based method at a cost of low additional computational complexity.

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A multi feature fusion clustering algorithm based on Q&A community

A multi feature fusion clustering algorithm based on Q&A com...

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International Conference on Cyberspace Technology (CCT 2013)

作者： Diandian Qian Yonghua Li Yueming Lu Key Laboratary of Trustworthy Distributed Computing and Service Ministry of Education School of Information and Communication Engineering Beijing University of Posts and Telecommunications China 100876

ISBN: (纸本)9781632660015

In this paper, a multi feature fusion clustering algorithm based on the Q&A community is presented, which to extract the candidate label by performing clustering on the Q-A pairs. It is proposed to combine TF/IDF, context information entropy, word length as feature to extract, select and score keywords. The experiment not only confirms effectiveness the compared with the traditional system, but also validates the precision of the multi feature fusion model.

关键词： Clustering Feature Fusion Q& A community TF/IDF Fusion reactions FUSION fusion (melting) Clustering algorithms Quality assurance Cluster Analysis Fusion, biological

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Combining SURF with MSER for Image Matching

Combining SURF with MSER for Image Matching

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IEEE International Conference on Granular computing

作者： Lei Tao Xiaojun Jing Songlin Sun Hai Huang Na Chen Yueming Lu School of Information and Communication Engineering Beijing University of Posts and Telecommunications Key Laboratory of Trustworthy Distributed Computing and Service (BUPT) Ministry of Education Beijing University of Posts and Telecommunications Beij

ISBN: (纸本)9781479912803

Many local features such as Speeded Up Robust Features (SURF) have been widely utilized in image matching due to their notable performances. However, the original SURF algorithm ignores the geometric relationship among SURF features. To overcome this drawback, an improved method combining SURF with Maximally Stable Extremal Regions (MSER) for image matching is proposed in this paper. By combining SURF features into groups and measuring the geometric similarity among features, the discriminative power of the grouped features has been significantly increased. Simulations show that the proposed method outperforms the original SURF algorithm both in match ratio and repeatability.

关键词： image matching SURF MSER geometric relationship

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A simplified implementation of barbell lifting Wavelets for Scalable Video Coding

A simplified implementation of barbell lifting Wavelets for ...

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International Conference on Cyberspace Technology (CCT 2013)

作者： Zhuoliang Zhang Xi Zhang Songlin Sun Xiaojun Jing Hai Huang Yueming Lu Key Laboratory of Trustworthy Distributed Computing and Service(BUPT) Ministry of Education Beijing University of Posts and Telecommunications China Zhang Laboratory Department of Information and Communication Engineering University of Electro-Communications Tokyo Japan

This paper proposes a simplified implementation of barbell lifting wavelets, which can be used in Wavelet-based Scalable Video Coding (WSVC). In the lifting scheme, barbell function is employed to generate prediction or update signals instead of only one pixel sample from single direction or each of bi-direction. The proposed method takes the corresponding pixel and some pixels around it into consideration and distributes the same weight to the neighbourhood pixels so as to simplify implementation. The method is compared with that without barbell lifting wavelets and a decreasing in standard deviation of residual images can be observed. Experiment results demonstrate that an improvement of coding efficiency is achieved with the proposed barbell lifting scheme.

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Multi-step traffic flow prediction model based on wavelet and echo state network

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Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (Engineering and Technology Edition) 2013年第3期43卷 646-653页

作者： Yang, Fei Fang, Bin-Xing Wang, Chun-Lu Zuo, Xing-Quan Li, Li-Xiang Ping, Yuan School of Computer Science Beijing University of Post and Telecommunications Beijing 100876 China Key Lab. of Trustworthy Distributed Computing and Service of the Ministry of Education of China Beijing University of Post and Telecommunications Beijing 100876 China Nanjing Panda Electronics Company Limited Nanjing 210002 China

In light of the noisy chaotic characteristics of traffic flow, a new multi-step traffic flow prediction model based on wavelet and echo state network was proposed. Utilizing multi-scale decomposition method of wavelet, the proposed model restricts the interference of noisy components to the dynamic behavior of the traffic flow;meanwhile it extracts the chaotic low-frequency component, which possesses most of the energy of traffic flow. In predicting the multi components concurrently, the strong prediction capacity of echo state network for chaotic low-frequency component was utilized effectively to ensure the accuracy of multi-step traffic flow prediction. The results of prediction of the real traffic flow in Xizhimen Bridge of Beijing show that the prediction accuracy is significantly improved by the proposed multi-step model in comparison with the traditional echo state network model. Under the condition of high prediction accuracy, the maximum predictable step is also increased by the proposed model.

关键词： Forecasting

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