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21st International Conference on Telecommunications, ICT 2014

作者： Qian, Wang Chunxiu, Xu Min, Zhao Siyu, Zhang Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing 100876 China

ISBN: (纸本)9781479951413

The dramatic development of high speed railway (HSR) has spurred great interest in extensive studies on the fading characteristics of the radio channel in all the relevant scenarios. Approved by the Ministry of Railways of China, single input single output (SISO) measurements were performed at 2.6 GHz with 40 MHz bandwidth along the Harbin-Dalian passenger dedicated railway line. In this paper, we provide some fading parameters including the mean excess delay, root-mean-square (RMS) delay spread, the number of paths and the delay Doppler spectrum under diverse HSR scenarios. Plain, viaduct and hilly terrain scenarios are all involved. Based on the extensive body of measured data, tapped-delay-line (TDL) models are established to characterize the time-varying wireless channel, which can be directly employed in the evaluation and comparison of various HSR transmission projects. All these results and models are expected to provide an insight into the behaviors and performance of wireless cellular communication in HSR scenarios. © 2014 IEEE.

关键词： Railroad transportation

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Propagation characteristics of high speed railway radio channel based on broadband measurements at 2.6 GHz

Propagation characteristics of high speed railway radio chan...

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2014 IEEE Wireless Communications and networking Conference, WCNC 2014

作者： Qian, Wang Chunxiu, Xu Muqing, Wu Min, Zhao Deshui, Yu Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing100876 China

ISBN: (纸本)9781479930838

With the rapid development of high speed railway (HSR), propagation characteristics of channels in HSR scenarios are therefore in urgent demand. We conducted numerous single input single output (SISO) measurements at 2.6 GHz with a bandwidth of 20 MHz along the Harbin-Dalian passenger dedicated railway line. Here, first analytical results in hilly terrains are provided. A double-slope path loss model fits measured data well and shadow fading is extracted to be log-normal distributed. Statistical results of small-scale fading are presented and compared in near regions and far regions relative to the transmitter, including the mean excess delay, root-mean-square (RMS) delay spread and the number of paths. Meanwhile, the delay Doppler spectrum is given out and verified. Finally, tapped-delay-line (TDL) channel model is established in detail based on the measured data. It is supposed that these results and models have a promotion for the further evaluation, simulation and design of the wireless communication system in HSR. © 2014 IEEE.

关键词： Railroad transportation

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Measurements and analysis of a 4×4 vehicle-to-ground MIMO channel using SAGE

Measurements and analysis of a 4×4 vehicle-to-ground MIMO c...

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2014 International Symposium on Wireless Personal Multimedia Communications, WPMC 2014

作者： Jiaqi, Yang Muqing, Wu Ruojun, Zhao Qian, Wang Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing100876 China

ISBN: (纸本)9789860334074

The widely used broadband wireless technology enables a novel application of providing high-quality communications between vehicles and traffic control centers, which is collectively referred to as vehicle-to-ground communications. Channel modeling is in rapidly increasing demand to design and optimize the vehicle-to-ground communication systems. And practical channel models are only available when accurate estimations of the channel parameters are feasible. By adopting quadrature encoding and spectrum spreading, a novel and low-cost measurement method is proposed in this paper. The method can be implemented to achieve channel matrix accurately and furthermore determinate the parameters of a MIMO channel by using the space-alternating generalized expectation-maximization (SAGE) algorithm. Then the method was carried out in a measurement of a vehicle-mounted 4×4 MIMO system. Both large-scale and small-scale fading are investigated and analyzed. A path loss (PL) model and characteristics of channel parameters including PDP, K-factor, angle of arrival (AOA), angle of departure (AOD) and spatial correlation matrixes for V2G channel modeling are given based on the estimations. These results offer a valuable reference for future studies. © 2014 National Institute of Information and Communicatio.

关键词： Quality control

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Comparative analysis on fading characteristics of the LTE-R channel in viaduct and hilly terrain scenarios

Comparative analysis on fading characteristics of the LTE-R ...

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2014 International Symposium on Wireless Personal Multimedia Communications, WPMC 2014

作者： Lin, Xiangli Xu, Chunxiu Siyu, Zhang Zhao, Ruojun Xiang, Xiao Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing100876 China

ISBN: (纸本)9789860334074

Long Term Evolution (LTE) system used in High-Speed Railway (HSR) has gained the increasing attention therefore the measurements and analysis of the broadband wireless channel for the HSR communication is urgently needed. This paper focuses on the special fading characteristics of viaduct and hilly terrain scenarios based on the extensive and practical multiple input multiple output (MIMO) measurements which is conducted on Harbin-Dalian passenger dedicated railway line at 2.6 GHz with a bandwidth of 40 MHz. Here, we provide the power delay profiles as the first analytical results. Large-scale fading parameters such as path loss and shadow fading are given and discussed. As for small-scale fading, two similar but not identical K-factor models in different scenario are presented for comparison. Through the analysis on the two typical scenarios, this paper provides great guiding significance for promoting evaluation, simulation and design of the wireless communication system based on Long Term Evolution Railway (LTE-R). © 2014 National Institute of Information and Communicatio.

关键词： Long Term Evolution (LTE)

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A Weak Password Cracker of UHF RFID Tags

A Weak Password Cracker of UHF RFID Tags

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Symposia and Workshops on Ubiquitous, Autonomic and Trusted Computing, UIC-ATC

作者： Zhentao Zhao Shufang Li Yang Kang Jiankai Li Shengguang Li Weijun Hong Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing People's Republic of China Police Key Laboratory of IoT Application of the Ministry of Public Security P.R.C First Research Institute of the Ministry of Public Security of PRC Beijing People's Republic of China

ISBN: (纸本)9781467372121

Under the ISO/IEC 18000-6C protocol of UHF RFID an electronic tag's information security is based on password protection, but its natural defect is unable to reject brute tests which can be exhaustive. By the protocol analysis, this article theoretically proves that tags' weak passwords can be cracked. Combined with a concrete Tag-Interrogator module a method for improving the cracking efficiency is given out with a special concise password library. Furthermore this paper implements the password cracker has carried on the exploration of distributed detection. By this method most electronic tags' passwords can be cracked within one week. The ultimate goal of this paper is to remind that UHF RFID industry projects should enhance the security level of tag's password practically.

关键词： Radiofrequency identification Dictionaries Security Encoding Protocols Databases IEC Standards

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SVM classification based on supervised subset density clustering

SVM classification based on supervised subset density cluste...

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International Conference on Advanced Communication Technology (ICACT)

作者： Yong Sun ZhenChao Sun Ran Zhan WeiDong Feng Geng Zhang ShiDong Liu Beijing University of Posts and Telecommunications Beijing Beijing CN School of Information and Communication Engineering Beijing University of Posts and Telecommunications China Beijing Key Laboratory of Network System Architecture and Convergence China State Grid Hubei electric power company China Electric Power Research Institute China

ISBN: (纸本)9781467381161

A way of combining SVM(Support Vector Machine) with Supervised Subset Density Clustering is proposed in this paper. How to minimize the training set of SVM by means of clustering is researched. Original center positions are of great importance to clustering accuracy. However the traditional clustering center choosing algorithm doesn't work properly when the same kind of samples aren't closely-spaced or the shape of the sample distribution isn't regular, an self-adaptive multiple centers choosing method is proposed to solve the problem. Another problem addressed in the paper is that there are areas that are covered by multi-class samples which is of great difficulty for traditional clustering to deal with, so a supervised method for the improved density clustering is designed to make out such areas and referring the samples to SVM. The experimental results show that the algorithm reduces the iteration time of the whole training process without compromising the accuracy and generalization capacity of the algorithm obviously.

关键词： Support vector machines Clustering algorithms Training Accuracy Classification algorithms Algorithm design and analysis Skin

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Robust multiband spectrum sensing in cognitive radio networks via exponentially embedded family criterion

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Journal of Communications 2014年第4期9卷 357-363页

作者： Qing, Haobo Liu, Yuanan Xie, Gang Liu, Kaiming Liu, Fang Beijing Key Laboratory of Work Safety Intelligent Monitoring School of Electronic Engineering Beijing University of Posts and Telecommunications Beijing 100876 China Beijing Key Laboratory of Network System Architecture and Convergence School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This paper proposes a robust spectrum sensing scheme for cognitive radio networks. The proposal performs spectrum sensing simultaneously over the total channels rather than a single channel at a time. It first estimates the number of occupied channels via the exponentially embedded family criterion, and then determines the occupancy status for each channel by sample power. The proposed method is robust to noise uncertainty since noise power estimation is avoided. Simulations demonstrate that our approach is robust to noise uncertainty and outperforms existing sensing methods. © 2014 Engineering and Technology Publishing.

关键词： Cognitive radio

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R-SDN: A recusive approach for scaling SDN

R-SDN: A recusive approach for scaling SDN

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2014 International Conference on Information and Communications Technologies, ICT 2014

作者： Dai, Wei Shou, Guochu Hu, Yihong Guo, Zhigang School of Information and Comminicaton Engineering Beijing University of Posts and Telecommunications Beijing Key Laboratory of Network System Architecture and Convergence Beijing China

ISBN: (纸本)9781849198431

Software-Defined networking provides a clean separation between control plane and data plane. In addition, control plane can configure and manage data plane in a centralized way. However, a centralized control plane introduces a problem in scaling SDN network. With the idea of network virtualization, we propose a recursive way to construct a new architecture of SDN so that the problem of scaling can be solved. A recursive algorithm is put forward to implement this new idea. As a kind of recursive model, Fibonacci series can be applied to R-SDN. Then, we take routing as typical scenario of experiment to test performance on this new architecture. Finally, we analyse experiment results based on principle and acquire some conclusions.

关键词： Virtual reality

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Efficient load balancing multipath algorithm for fiber-wireless network virtualization

Efficient load balancing multipath algorithm for fiber-wirel...

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2014 International Conference on Information and Communications Technologies, ICT 2014

作者： Meng, Xinrui Shou, Guochu Hu, Yihong Guo, Zhigang Beijing Key Laboratory of Network System Architecture and Convergence School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781849198431

The fiber-wireless network which is a combination of the fiber subnetwork and wireless subnetwork has provided high bandwidth access with ubiquity and mobility. But traditional single-path transmission cannot satisfy people's requirements for network performance due to various services. Multipath algorithms have been proposed as a solution to the network congestion. The multipath algorithm in traditional network has some limits in such heterogeneous networks. The application of network virtualization which can hide the differences of underlying physical infrastructures provides a potential method to solve this problem. In this paper we propose a Modified Weighted Round Robin (MWRR) algorithm based on the model of fiber-wireless network virtualization. Specific scheduling schemes will be arranged due to the quality of service requests and the states of links via the global view in the control plane. The simulation results show the smaller end-to-end delay and better load balancing.

关键词： Heterogeneous networks

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A Compact Platform-Tolerant Antenna for RFID Tag With Stable Gain

A Compact Platform-Tolerant Antenna for RFID Tag With Stable...

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Asia-Pacific Microwave Conference

作者： Weijun Hong Qing Chen Li Deng Yang Fu Zhentao Zhao Xiong Xiong Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications College of Electronic and Information Engineering South China University of Technology

ISBN: (纸本)9781479987689

A low-profile ultra high frequency (UHF) radio frequency identification (RFID) tag antenna is proposed with a compact size of 80 × 30mm~2 and stable gain while attaching on different mediums. The antenna is composed of a quarter-wave length patch etching on FR4 substrate and a suspended inductively coupling loop who connected with a RFID chip. The antenna acts as an omnidirectional electric monopole antenna and directional aperture antenna while mounted on dielectric and conductor platforms respectively. Antenna gain at the normal direction of antenna surface (θ = 0°, φ = 0°) fluctuates less than 2dB with peak value 0dBi while the antenna is mounted on different mediums, resulting a unique long reading distance under different application scenarios.

关键词： Radio frequency identification Tag antenna Broad-band Platform-tolerant

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