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International wireless communications and Mobile Computing Conference

作者： Haozhou Huang Xing Zhang Xiang Hu Pengwei Zhang Yongjing Li Wireless Signal Processing and Network Laboratory Key Lab of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications China

ISBN: (纸本)9781509003051

Jamming emits white Gaussian noise that causes interference to both the legitimate receiver and eavesdropper. It has been an effective method for improving physical-layer security in wireless communication. In this paper, cautious jamming strategy based on optimal jammer selection method is proposed. More specifically, by using perfect channel state information, cautious jamming strategy selects an optimal jammer to improve the secrecy performance. For the purpose of comparison, we consider the direct jamming strategy and the adaptive jamming strategy as benchmark schemes. Closed-form expressions of the exact intercept probability for three jamming strategies are derived over Rayleigh fading channels and the theoretical analysis is validated by Monte-Carlo simulation. Both the analytical and the simulation results show that: 1) increasing the power of jammer is an effective approach to mitigate the intercept probability;2) the intercept probability can be decreased and the wiretapped range of eavesdropper can be reduced by increasing the number of jammer;3) by using perfect CSI and selecting optimal jammer, cautious jamming strategy outperforms direct jamming strategy and adaptive jamming strategy.

关键词： Physical-layer security Optimal jammer selection Jamming strategy Intercept probability

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Secure Transmission via Jamming in Cognitive Radio Networks with Possion Spatially Distributed Eavesdroppers

Secure Transmission via Jamming in Cognitive Radio Networks ...

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IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio communications

作者： Xiang Hu Xing Zhang Haozhou Huang Yongjing Li Wireless Signal Processing and Network Laboratory Key Lab of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781509032556

This paper studies the physical layer security (PLS) in an underlay cognitive radio (CR) network. Under an interference constraint set by the primary user, we propose a secure transmission scheme from a secondary source to a secondary destination in the presence of spatially random eavesdroppers, the distribution of which is modeled as a homogeneous Possion point process (PPP). In addition to transmitting the message signal, the secondary source is allowed to use part of its power to transmit jamming signals in order to interfere the eavesdroppers. Assuming that the secondary destination has the knowledge of the jamming signals, we derive the closed-form expression for the connection outage probability and an easy-to-compute expression for the secrecy outage probability to characterize the reliability and the security performance, respectively. Moreover, we determine the optimal power allocation factor and wiretap code rates which maximize the secrecy throughput of the wiretap channel under secrecy outage probability constraint.

关键词： Physical layer security (PLS) Cognitive radio (CR) networks Possion point process (PPP) Jamming Secrecy throughput

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A Low-Complexity Tree Search based quasi-ML Receiver for SCMA System

A Low-Complexity Tree Search based quasi-ML Receiver for SCM...

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2015 IEEE International Conference on Computer and communications(ICCC 2015)

作者： Zou Jia Zhao Hui Li Xing Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing & Network LabBUPT

Sparse code multiple access(SCMA) which is overloaded by carrying more users than its resource blocks, is different from conventional multiple access method. It can improve spectrum efficiency to solve the problem of large amounts of telecommunication data. Conventional message passing algorithm(MPA) receiver has been used in SCMA, but it has a relatively high complexity. In this paper, we propose a new low-complexity quasi maximum likelihood(quasi-ML) receiver to further reduce the complexity. Quasi-ML receiver is improved for the specific characteristic of SCMA. Numerical results demonstrate that the quasi-ML detector achieves significantly less computational complexity than the classic MPA detector, with a little performance loss. The superior performance of the proposed algorithm is demonstrated by theoretic analysis as well as simulation results.

关键词： Non-orthogonal multiple access SCMA MPA Quasi-ML QR decomposition Tree search

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A Novel Codeword Grouped SCMA

A Novel Codeword Grouped SCMA

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The 6th International Symposium on Microwave,Antenna,Propagation,and Electromagnetic Compatibility Technologies(MAPE 2015)

作者： Jun Wang Hui Zhao Yuexing Peng Sha Liu Senyao Zheng Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing ＆ Network LabBUPT

In the future 5G, the fast-growing requirements of massive connectivity, higher data-rate transmissions and multiple services should be matched with new multiple access technology. Non-orthogonal multiple access, nowadays, is considered as an effective method to solve those problems. Some non-orthogonal multiple access technologies, e.g. low density signature（LDS） and sparse code multiple access（SCMA）, are proposed nowadays for substantial connectivity together with spectrum efficiency promotion. Instead of spreading data symbols over orthogonal or near orthogonal code sequences in CDMA, those non-orthogonal multiple access technologies take advantage of non-orthogonal code sequences. The LDS repeatedly spreads quadrature amplitude modulation（QAM） symbol according to the low density sequence, while the SCMA assigns different predefined codebooks to multiple layers. However, the SCMA codebooks made from multi-dimensional constellations are designed under the condition of same modulation order for each layer. The design scheme of SCMA codebook is regardless of the orthogonality among some certain layers. A novel codeword grouped SCMA（CG-SCMA） proposed in this paper allows diverse modulations and enhances the applicability of the nonorthogonal multiple access technology. Instead of mapping incoming bits to multi-dimensional codewords from predefined codebooks in SCMA, the procedure of symbols to complex codewords is divided into two steps: grouped indicator sequence spread and grouped symbol sequence rotation. The grouped symbol sequence rotation decreases the interference among layers and increases the signal space diversity, which is regarded as the main source of performance promotion. Simulation results are presented to show the significant performance gain of CG-SCMA comparing with SCMA and LDS.

关键词： CG-SCMA LDS SCMA MPA codeword codebook grouped indicator sequence spread grouped symbol sequence rotation grouped indicator matrix diverse modulations

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Low-complexity Interference Cancellation Receiver for Sparse Code Multiple Access

Low-complexity Interference Cancellation Receiver for Sparse...

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The 6th International Symposium on Microwave,Antenna,Propagation,and Electromagnetic Compatibility Technologies(MAPE 2015)

作者： Jia Zou Hui Zhao Wenxiu Zhao Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing ＆ Network LabBUPT

Sparse code multiple access（SCMA） is a proposed candidate for multiple access method in 5G telecommunication. In SCMA system, the classic receiver is message passing algorithm（MPA）. MPA can reach a near optimal performance, but the computation process is complicated and time-consuming, so MPA is suitable for advanced terminal. But for simple terminal such as sensor node, large mount of calculations are difficult to bear. In this paper, we propose two interference cancellation（IC） related receivers to reduce complexity, including serial interference cancellation（SIC） and jointed serial interference cancellation with MPA algorithm（Jointed SIC-MPA）. It’s important to emphasize that these two IC related algorithms are designed jointed with multidimensional modulation constellation design. We propose a new method to generate multi-dimensional constellation. Both of them have lower complexity compared with classic MPA receiver.

关键词： SCMA MPA SIC jointed SIC-MPA nonorthogonal multiple access

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Low-complexity interference cancellation receiver for sparse code multiple access

Low-complexity interference cancellation receiver for sparse...

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International Symposium on Microwave, Antenna, Propagation and EMC Technologies for wireless communications (MAPE)

作者： Jia Zou Hui Zhao Wenxiu Zhao Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing & Network Lab BUPT Beijing China

Sparse code multiple access (SCMA) is a proposed candidate for multiple access method in 5G telecommunication. In SCMA system, the classic receiver is message passing algorithm (MPA). MPA can reach a near optimal performance, but the computation process is complicated and time-consuming, so MPA is suitable for advanced terminal. But for simple terminal such as sensor node, large mount of calculations are difficult to bear. In this paper, we propose two interference cancellation (IC) related receivers to reduce complexity, including serial interference cancellation (SIC) and jointed serial interference cancellation with MPA algorithm (Jointed SIC-MPA). It's important to emphasize that these two IC related algorithms are designed jointed with multi-dimensional modulation constellation design. We propose a new method to generate multi-dimensional constellation. Both of them have lower complexity compared with classic MPA receiver.

关键词： Receivers Performance evaluation Image resolution TV Complexity theory

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A low-complexity tree search based quasi-ML receiver for SCMA system

A low-complexity tree search based quasi-ML receiver for SCM...

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International Conference on Computer and communications (ICCC)

作者： Zou Jia Zhao Hui Li Xing Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing & Network Lab BUPT Beijing China

ISBN: (纸本)9781467381277

Sparse code multiple access (SCMA) which is overloaded by carrying more users than its resource blocks, is different from conventional multiple access method. It can improve spectrum efficiency to solve the problem of large amounts of telecommunication data. Conventional message passing algorithm (MPA) receiver has been used in SCMA, but it has a relatively high complexity. In this paper, we propose a new low-complexity quasi maximum likelihood (quasi-ML) receiver to further reduce the complexity. Quasi-ML receiver is improved for the specific characteristic of SCMA. Numerical results demonstrate that the quasi-ML detector achieves significantly less computational complexity than the classic MPA detector, with a little performance loss. The superior performance of the proposed algorithm is demonstrated by theoretic analysis as well as simulation results.

关键词： Modulation Receivers Complexity theory Measurement Sparse matrices Mathematical model Matrix decomposition

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Scheme for realizing passive quantum key distribution with heralded single-photon sources

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Physical Review A 2016年第3期93卷 032312-032312页

作者： Qin Wang Chun-Hui Zhang Xiang-Bin Wang Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing 210003 China Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China Department of Physics and State Key Laboratory of Low Dimensional Quantum Physics Tsinghua University Beijing 100084 China Jinan Institute of Quantum Technology Shandong Academy of Information Technology Jinan China

We present a scheme for realizing passive quantum key distribution with heralded single-photon sources. In this scheme, the idler light from the parametric down-conversion process is split into two parts and sent into two local detectors individually. Then all the clicking and nonclicking events are used to herald the arrival and nonarrival of the signal light. As a result, a precise estimation of the behavior of the single-photon pulses can be achieved without changing the light intensity. Furthermore, we compare our scheme with other existing methods with the Bennett-Brassard 1984 (BB84) protocol through numerical simulations. Our simulations demonstrate that the performance of our scheme can greatly overcome other existing practical methods and approach very close to the asymptotic case of using infinite-decoy-state methods.

关键词： Quantum cryptography

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Deterministic realization of collective measurements via photonic quantum walks

arXiv

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arXiv 2017年

作者： Hou, Zhibo Tang, Jun-Feng Shang, Jiangwei Zhu, Huangjun Li, Jian Yuan, Yuan Wu, Kang-Da Xiang, Guo-Yong Li, Chuan-Feng Guo, Guang-Can Key Laboratory of Quantum Information University of Science and Technology of China CAS Hefei230026 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei230026 China Naturwissenschaftlich-Technische Fakultät Universität Siegen Siegen57068 Germany Beijing Key Laboratory of Nanophotonics Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China Institute for Theoretical Physics University of Cologne Cologne50937 Germany Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing210003 China

Collective measurements on identically prepared quantum systems can extract more information than local measurements, thereby enhancing information-processing efficiency. Although this nonclassical phenomenon has been known for two decades, it has remained a challenging task to demonstrate the advantage of collective measurements in experiments. Here we introduce a general recipe for performing deterministic collective measurements on two identically prepared qubits based on quantum walks. Using photonic quantum walks, we realize experimentally an optimized collective measurement with fidelity 0.9946 without post selection. As an application, we achieve the highest tomographic efficiency in qubit state tomography to date. Our work offers an effective recipe for beating the precision limit of local measurements in quantum state tomography and metrology. In addition, our study opens an avenue for harvesting the power of collective measurements in quantum information processing and for exploring the intriguing physics behind this power. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum optics

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Improved DFT-based channel estimation for downlink LTE system with adding virtual carrier frequency response

Improved DFT-based channel estimation for downlink LTE syste...

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11th International Conference on wireless communications, networking and Mobile Computing (WiCOM 2015)

作者： Hongyu Zhu Tao Peng Wenbo Wang Wireless Signal Processing and Network Lab Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts & Telecommunications China

ISBN: (纸本)9781510821279

In Long Term Evolution (LTE) systems, some subcarriers at the borders of the allocated bandwidth are known as virtual subcarriers which are not used for data transmission. Conventional DFT-based channel estimation methods encounter performance degradation due to low SNR and the edge effect caused by virtual subcarriers. Adding virtual carrier frequency responses (VCFR) properly at receivers is proved to be able to effectively mitigate edge effect. The proposed method adopts the VCFR addition method into practical downlink LTE systems to alleviate edge effect. A novel noise eliminating strategy based on energy detection is demonstrated in the proposed method to improve the overall performance especially in low SNR scenario. Compared with existing DFT-based channel estimation methods, simulation results of the proposed channel estimation method showed a relatively lower Mean Square Error (MSE) and raw Bit Error Rate (BER) under several kinds of standard channel models with wide SNR range. The proposed method is also proved to have roughly the same level of complexity as conventional DFT-based channel estimation method.

关键词： Channel Estimation Energy Detection Long Term Evolution Virtual Subcarrier channel estimation Long Term Evolution Edge effect Bit error rate Local thermodynamic equilibrium low SNR Subcarriers Virtual frequency response Downlink

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