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BER analysis of STBC hybrid carrier system based on WFRFT with frequency domain equalization

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science China(Information sciences) 2018年第8期61卷 147-159页

作者： Zhenduo WANG Lin MEI Xuejun SHA Naitong ZHANG communication Research Center Harbin Institute of Technology science and technology on Information Transmission and Dissemination in communication networks laboratory

The inherent characteristic of hybrid carrier(HC) scheme based on the weighted-type fractional Fourier transform(WFRFT) is revealed. The proposed linear combination of single carrier(SC) and multicarrier’s(MC) characteristics is helpful to balance the conflicting requirements and achieve the comparative analysis of SC/MC. As an example, analytical SER/BER expressions of HC system with zero forcing(ZF)and minimum mean square error(MMSE) equalization are derived. In addition, the derived BER expressions are extended to multi-input systems. A unified framework of space time block code(STBC) HC scheme is proposed with two WFRFT modules at the transmitter or receiver, where STBC-SC and STBC-MC systems are the special cases of the novel structure.

关键词： single carrier multi-carrier weighted-type fractional Fourier transform hybrid carrier zero forcing minimum mean square error space time block code

Spectrum sensing based on angular reciprocity in cognitive satellite communication system

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science China(Information sciences) 2021年第8期64卷 117-126页

作者： Jiancun FAN Yong BAN Jie LUO Ying ZHANG Xinmin LUO School of Information and communications Engineering Xi'an Jiaotong University Science and Technology on Communication Networks Laboratory

Satellite communication is attracting increasing attention owing to its freedom from geographical constraints. However, its spectrum resources are limited, and it is susceptible to interferences. Therefore,cognitive radio technology can be used to detect and prevent interferences as well as improve spectrum utilization.To improve the spectrum sensing performance, an angle reciprocity-based spectrum sensing(ARSS)scheme is proposed in this study. The scheme exploits the reciprocity between the known beam’s central angle and the unknown signal’s arrival angle, with the reciprocity controlled by the narrow characteristic of the satellite’s beam owing to long-distance propagation. In this scheme, we use the beam’s central angle instead of the signal’s actual angle to process the received signal, and then the processed data are used as the sensing statistics for spectrum sensing. The simulation results show that the proposed ARSS scheme exhibits better satellite spectral sensing performance compared with the energy detector(ED).

关键词： satellite communications spectrum sensing angle reciprocity energy detector

Vector Segment Routing for Large-Scale Multilayer Satellite Network

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Journal of communications and Information networks 2023年第1期8卷 24-36页

作者： Weigang Bai Hongming Yang Jincheng Tong Zhaotao Qin Ruochen Lyu Xidian University Xi’an 710000 Science and Technology on Communication Networks Laboratory Shijiazhuang 050000China China Academy of Space technology Beijing 100000China

With the expansion of satellite constellation,routing techniques for small-scale satellite networks have problems in routing overhead and forwarding efficiency.This paper proposes a vector segment routing method for large-scale multi layer satellite networks.A vector forwarding path is built based on the location between the source and the destination.Data packets are forwarded along this vector path,shielding the influence of satellite motion on routing forwarding.Then,a dynamic route maintenance strategy is suggested.In a multi layer satellite network,the low-orbit satellites are in charge of computing the routing tables for one area,and the routing paths are dynamically adjusted in the area in accordance with the network.The medium-orbit satellites maintain the connectivity of vector paths in multiple segmented areas.The forwarding mode based on the source and destination location improves the forwarding efficiency,and the segmented route maintenance mode decreases the routing overhead.The simulation results indicate that vector segment routing has significant performance advantages in end-to-end delay,packet loss rate,and throughput in a multi layer satellite network.We also simulate the impact of routing table update mechanism on network performance and overhead and give the performance of segmented vector routing in multi layer low-orbit satellite networks.

关键词： routing technique routing overhead vector segment routing network load throughput

Directional modulation with distributed receiver selection for secure wireless communications

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science China(Information sciences) 2021年第12期64卷 215-225页

作者： Hongyan ZHANG Yue XIAO Wanbin TANG Gang WU Hong NIU Xiaotian ZHOU National Key laboratory of science and technology on communications University of Electronic Science and Technology of China Science and Technology on Communication Networks Laboratory The 54th Research Institute of China Electronics Technology Group Corporation

In this paper, a novel directional modulation with distributed receiver selection(DM-DRS)scheme is proposed for secure wireless communications. In DM-DRS, a particular subset of receivers is activated and part of the information bits are modulated by the index of the activation pattern, in addition to traditional digital modulation. Especially, the scrambling matrix is introduced for the sake of preventing the eavesdropping. Moreover, the performances of bit error rate(BER) in terms of the union bound for both the legitimate user and eavesdropper are respectively derived in the context of an optimal joint maximum likelihood(ML) detector, and the theoretical BER upper bounds are demonstrated to be tight by the numerical results. In the context of the discrete-input and continuous-output system, the ergodic secrecy rates of the legitimate user and the eavesdropper are obtained, the secrecy rate is also quantified. Furthermore,our numerical results exhibit that DM-DRS can achieve an increased transmission rate compared to its traditional directional modulation with cooperative receivers(DM-CR) and spatial and direction modulation(SDM) counterparts, while guaranteeing an improved BER performance.

关键词： directional modulation distributed receiver selection bit error rate secrecy rate

Load Distribution of Base Stations in User-Centric Heterogeneous UDN

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中国通信:英文版 2023年第9期20卷 227-234页

作者： Xuanli Wu Xu Chen Ziyi Xie Wei Wu Tianzhu Pan Yong Li communication Research Center Harbin Institute of TechnologyHarbin 150006China Science and Technology on Communication Networks Laboratory Shijiazhuang 130100China 54th Research Institute of China Electronics technology Corporation Shijiazhuang 130100China

In ultra-dense networks(UDN),multiple association can be regarded as a user-centric pattern in which a user can be served by multiple base stations(BSs).The data rate and quality of service can be improved.However,BSs in user-centric paradigm are required to serve more users due to this multiple association scheme.The improvement of system performance may be limited by the improving load of BSs.In this letter,we develope an analytical framework for the load distribution of BSs in heterogeneous user-centric UDN.Based on open loop power control(OLPC),a user-centric scheme is considered in which the clustered serving BSs can provide given signal to interference plus noise ratio(SINR)for any typical user.As for any BS in different tiers,by leveraging stochastic geometry,we derive the Probability Mass Function(PMF)of the number of the served users,the Cumulative Distribution Function(CDF)of total power consumption,and the CDF bounds of downlink sum data rate.The accuracy of the theoretical analysis is validated by numerical simulations,and the effect the system parameters on the load of BSs is also presented.

关键词： heterogeneous ultra-dense network load distribution open loop power control stochastic geometry user-centric

A Novel Orthogonal LoRa Multiple Access Algorithm for Satellite Internet of Things

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China communications 2022年第3期19卷 279-289页

作者： Chengwen Zhang Liankai Wang Libin Jiao Shipeng Wang Jun Shi Jia Yue School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150080China Science and Technology on Communication Networks Laboratory Shijiazhuang 050081China Key laboratory of Police Wireless Digital communication Ministry of Public SecurityHarbin 150001China

In recent years,LoRa has been extensively researched in the satellite Internet of Things(IoT).However,the multiple access technology of LoRa is still one of the bottlenecks of satellite IoT.To improve the multiple access performance of LoRa satellite IoT,based on the orthogonality of LoRa symbols in the fractional domain,this paper proposes a low complexity Orthogonal LoRa Multiple Access(OLMA)algorithm for multiple LoRa users occupying the same frequency bandwidth.The algorithm introduces the address code to divide the fractional bandwidth into multiple parts,and the OLMA users with different address codes occupy different parts to transmit the information code,thus avoiding mutual interference caused by collisions in the same frequency bandwidth.The multiple access capability of OLMA can be flexibly configured only by simply adjusting the length of the address code according to the actual application requirements of data transmission.Theoretical analysis and simulation results show that the OLMA algorithm can greatly improve the multiple access capability and the total transmission bit rate of LoRa IoT without changing the existing LoRa modulation parameters and process.

关键词： LoRa satellite Internet of Things multiple access fractional domain linear frequency modulation

Energy-efficient UAV-NOMA aided wireless coverage with massive connections

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science China(Information sciences) 2023年第12期66卷 194-208页

作者： Yuqiao TONG Min SHENG Junyu LIU Nan ZHAO School of Information and communication Engineering Dalian University of Technology State Key laboratory of Integrated Services networks Xidian University

In this paper, we propose an unmanned aerial vehicle(UAV)-assisted wireless coverage scheme,wherein UAVs help to serve the cell-edge users for ground base stations based on non-orthogonal multiple access(NOMA). The combined benefits of wide coverage and massive connections enable UAV-NOMA-aided wireless coverage to effectively meet the requirements of the Internet of Everything. Meanwhile, energy efficiency(EE) is maximized via resource allocation to address the issue of the power supply bottleneck of UAVs. The non-convex optimization problem is transformed into two convex subproblems of trajectory optimization and power allocation, and an iterative alternating optimization algorithm is proposed to address it effectively. Moreover, we further considered the energy consumption of the ground base stations, effectively minimizing it by optimizing precoding while guaranteeing average throughput. Numerical results verify the effectiveness of the proposed UAV-aided wireless coverage scheme and demonstrate the EE improvement.

关键词： energy efficiency non-orthogonal multiple access trajectory optimization unmanned aerial vehicle wireless coverage

Algebraic-Based Nonbinary LDPC Codes with Flexible Field Orders and Code Rates

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China communications 2017年第4期14卷 111-119页

作者： Hengzhou Xu Dan Feng Cheng Sun Baoming Bai State Key laboratory of Integrated Service networks Xidian University Xi'an 710071 China Science and Technology on Communication Networks Laboratory Shijiazhuang 050081 China

In this paper, we study the rank of matrices over GF(2~p),and propose two construction methods for algebraic-based nonbinary LDPC codes from an existing LDPC code, referred to as the original code. By multiplying all elements of each column of the binary parity-check matrix H corresponding to the original code with the same nonzero element of any field, the first class of nonbinary LDPC codes with flexible field order is proposed. The second method is to replace the nonzero elements of some columns in H with different nonzero field elements in a given field, and then another class of nonbinary LDPC codes with various rates is obtained. Simulation results show that the proposed nonbinary LDPC codes perform well over the AWGN channel with the iterative decoding algorithms.

关键词： LDPC码编码速率多进制代数非零元素订单基础 AWGN信道

Manifold optimization assisted centralized hybrid precoding for cell-free massive MIMO systems

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science China(Information sciences) 2023年第11期66卷 305-306页

作者： Jie LUO Jiancun FAN Yawen WANG Jinbo ZHANG School of Information and communications Engineering Xi'an Jiaotong University Science and Technology on Communication Networks Laboratory the 54th Research Institute of CETC

In the sixth generation(6G) wireless communication, cellfree massive multiple-input multiple-output(MIMO) has emerged as a promising technology due to it can improve macro diversity gain, enhance edge user service quality, and reduce path loss [1]. To suppress inter-user interference and improve spectral efficiency, the design of the precoding scheme is important.

关键词： SCHEME