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non-orthogonal multiple access in Cell-Free Massive MIMO Networks

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China Communications 2020年第8期17卷 81-94页

作者： Yao Zhang Haotong Cao Meng Zhou Longxiang Yang Department of Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and TelecommunicationsNanjing 210003China

In this paper, we investigate the downlink performance of cell-free massive multi-input multi-output non-orthogonal multiple access(CF-m MIMO-NOMA) system with conjugate beamforming precoder and compare against the orthogonal multiple access(OMA) counterpart. A novel achievable closed-form spectral efficiency(SE) expression is derived, which characterizes the effects of the channel estimation error, pilot contamination, imperfect successive interference cancellation(SIC) operation, and power optimization technique. Then, motivated by the closedform result, a sum-SE maximization algorithm with the sequential convex approximation(SCA) is proposed, subject to each AP power constraint and SIC power constraint. Numerical experiments indicate that the proposed sum-SE maximization algorithms have a fast converge rate, within about five iterations. In addition, compared with the full power control(FPC) scheme, our algorithms can significantly improve the achievable sum-SE. Moreover, NOMA outperforms OMA in many respects in the presence of the proposed algorithms.

关键词： non-orthogonal multiple access CF-mMIMO successive interference cancellation power optimization sequential convex approximation

Secure Transmission in Downlink non-orthogonal multiple access Based on Polar Codes

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China Communications 2021年第9期18卷 221-235页

作者： Ce Sun Zesong Fei Bin Li Xinyi Wang Nan Li Lijie Hu School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China Nanjing University of Information Science and Technology Nanjing 210044China China Mobile Research Institute Beijing 100053China

non-orthogonal multiple access(NOMA)is deemed to have a superior spectral efficiency and polar codes have became the channel coding scheme for control channel of enhanced mobile broadband(eMBB)in the fifth generation(5G)communication systems.In this paper,NOMA combined with polar codes is used to achieve secure transmission.Both degraded wiretap channel and non-degraded wiretap channel are considered,where an eavesdropper intercepts the communication between base station(BS)and users.For the degraded wiretap channel scenario,a secure polar encoding scheme is proposed in NOMA systems with power allocation to achieve the maximum secrecy capacity.With regard to the nondegraded wiretap channel,a polar encoding scheme with multiple-input-single-output(MISO)system is proposed,where artificial noise is generated at BS to confuse the eavesdropper’s channel via transmit beamforming.The security and the secure rate are employed respectively in order to measure the secrecy performance.We prove that the proposed schemes for each scenario can achieve the secure rate and can transmit the signal securely and reliably.The simulation results show that the eavesdropper hardly decoding the secure signal when the legitimate receiver can decode the signal with very low block error rate(BLER).

关键词： physical layer security polar codes non-orthogonal multiple access artificial noise

Analysis of non-orthogonal multiple access for 5G

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China Communications 2016年第S2期13卷 52-66页

作者： Yingmin Wang Bin Ren Shaohui Sun Shaoli Kang Xinwei Yue School of Information and Communication Engineering Beijing University of Posts & Telecommunications State Key Laboratory of Wireless Mobile Communications China Academy of Telecommunication Technology National Engineering Laboratory of New Generation Mobile Communication Network and Chip Technology China Academy of Telecommunication Technology School of Electronic and Information Engineering Beihang University

The major challenge faced by the fifth generation(5G) mobile network is higher spectral efficiency and massive connectivity,i.e.,the target spectrum efficiency is 3 times over 4G,and the target connection density is one million devices per square kilometer.These requirements are difficult to be satisfied with orthogonal multiple access(OMA) schemes.non-orthogonal multiple access(NOMA) has thus been proposed as a promising candidate to address some of the challenges for 5G.In this paper,a comprehensive survey of different candidate NOMA schemes for 5G is presented,where the usage scenarios of5 G and the application requirements for NOMA are firstly discussed.A general framework of NOMA scheme is established and the features of typical NOMA schemes are analyzed and compared.We focus on the recent progress and challenge of NOMA in standardization of international telecommunication union(ITU),and 3rd generation partnership project(3GPP).In addition,prototype development and future research directions are also provided respectively.

关键词： 5G non-orthogonal multiple access NOMA SCMA PDMA MUSA MPA SIC

non-orthogonal multiple access Schemes for 5G

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ZTE Communications 2016年第4期14卷 11-16页

作者： YAN Chunlin YUAN Zhifeng LI Weimin YUAN Yifei ZTE Corporation Shengzhen 518057 China

multiple access scheme is one of the key techniques in wireless communication systems. Each generation of wireless communica-tion is featured by a new multiple access scheme from 1G to 4G. In this article we review several non-orthogonal multiple access schemes for 5G. Their principles, advantages and disadvantages are discussed, and followed by a comprehensive comparison of these solutions from the perspective of user overload, receiver type, receiver complexity and so on. We also discuss the applica-tion challenges of non-orthogonal multiple access schemes in 5G.

关键词： 5G non-orthogonal multiple access mMTC

User scheduling and power allocation for downlink multi-cell multi-carrier NOMA systems

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Digital Communications and Networks 2023年第1期9卷 252-263页

作者： Abuzar B.M.Adam Xiaoyu Wan Zhengqiang Wang School of Communications and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China

In non-orthogonal multiple access(NOMA),the best way to fully exploit the benefits of the system is the efficient resource allocation.For the NOMA power domain,the allocation of power and spectrum require solving the mixed-integer nonlinear programming NP-hard problem.In this paper,we investigate user scheduling and power allocation in Multi-Cell Multi-Carrier NOMA(MCMC-NOMA)networks.To achieve that,we consider Weighted Sum Rate Maximization(WSRM)and Weighted Sum Energy Efficiency Maximization(WSEEM)problems.First,we tackle the problem of user scheduling for fixed power using Fractional Programming(FP),the Lagrange dual method,and the decomposition method.Then,we consider Successive Pseudo-Convex Approximation(SPCA)to deal with the WSRM problem.Finally,for the WSEEM problem,SPCA is utilized to convert the problem into separable scalar problems,which can be parallelly solved.Thus,the Dinkelbach algorithm and constraints relaxation are used to characterize the closed-form solution for power allocation.Extensive simulations have been implemented to show the efficiency of the proposed framework and its superiority over other existing schemes.

关键词： Weighted sum rate Weighted energy efficiency non-orthogonal multiple access Successive pseudo-convex approximation Fractional programming

Intelligent reflecting surface assisted untrusted NOMA transmissions: a secrecy perspective

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Science China(Information Sciences) 2023年第9期66卷 226-238页

作者： Dawei WANG Xuanrui LI Yixin HE Fuhui ZHOU Qihui WU School of Electronics and Information Northwestern Polytechnical University Research & Development Institute of Northwestern Polytechnical University in Shenzhen College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Nanjing University of Aeronautics and Astronautics

In this paper, we investigate the intelligent reflecting surface(IRS) assisted secure transmissions for the untrusted non-orthogonal multiple access(NOMA) network threatened by an external eavesdropper,where the near user and two untrusted far users receive the privacy information from the transmitter assisted by the IRS’s passive reflection. To protect the privacy information against internal and external eavesdropping, we first provide a comprehensive analysis of the secrecy rates, which can offer suitable methods for separately handling the internal and external secrecy performance. Following the above results, we formulate a secrecy rate maximization problem by optimizing the transmission power allocation and phase shifts. To achieve this goal, we decouple the non-convex optimization problem into the external security problem and the internal security problem. Then, we propose a heuristic simulated annealing algorithm to iteratively solve the above problems, where the semi-definite relaxation(SDR) technique, the singular value decomposition(SVD) technique, and the Lagrange multiplier method are utilized to relax the problems and optimize the power allocation and phase shifts. Finally, numerical results show that the proposed scheme can improve the secrecy rate compared with the existing IRS-aided secure NOMA transmission schemes.

关键词： intelligent reflecting surface non-orthogonal multiple access security untrusted users

Distortion minimization for multimedia transmission in NOMA HAP-UAV integrated aerial access networks

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Chinese Journal of Aeronautics 2022年第9期35卷 81-94页

作者： Guobin ZHANG Zhu HAN Hang XIN Xin WEI Boya DI School of Electrical Engineering and Intelligentization Dongguan University of TechnologyDongguan 523808China Department of Electrical and Computer Engineering and Department of Computer Science University of HoustonTX77004USA School of Computer Science and Technology Dongguan University of TechnologyDongguan 523808China Department of Computing Imperial CollegeLondon SW72AzUK

Aerial access networks have been envisioned as a promising 6G solution to enhance the ground communication systems in both coverage and capacity. To better utilize the spectrum and fully explore different channel characteristics, this paper constructs an integrated network comprising the High Altitude Platform(HAP) and Unmanned Air Vehicles(UAVs) with the nonorthogonal multiple access(NOMA) technology. In order to improve the transmission quality of images and videos, a power management scheme is proposed to minimize the distortion of the transmissions from the HAP and UAVs to the terminals. The power control is formulated as a non-convex problem constrained by the maximal transmit power and the minimal terminal rate requirements. The variable substitution and the first-order Tailor’s expansion is used to transform it into a sequence of convex problems, which are subsequently solved through the gradient projection method. Simulation demonstrates the signal distortion and error rate improvement achieved by the proposed algorithm.

关键词： Aerial access Networks High Altitude Platform non-orthogonal multiple access Sixth-Generation Unmanned Air Vehicles

Help from space:grant-free massive access for satellite-based IoT in the 6G era

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Digital Communications and Networks 2022年第2期8卷 215-224页

作者： Neng Ye Jihong Yu Aihua Wang Rongrong Zhang School of Information and Electronics Beijing Institute of TechnologyBeijing100081China Information Engineering College Capital Normal UniversityBeijing100048China

The Sixth-Generation(6G)standard for wireless communications is expected to realize ubiquitous coverage for massive Internet of Things(IoT)networks by 2030.Satellite-based communications are recognized as a highly promising technical enabler to satisfy IoT service requirements in the 6G era.This study analyzes multiple access technologies,which are essential for the effective deployment of satellite-based IoT.First,we thoroughly investigate the existing research related to massive access,including information-theory considerations as well as non-orthogonal multiple access(NOMA)and Random access(RA)technologies.Then,we explore the influence of the satellite transmission environment on multiple access technologies.Based on this study,a non-orthogonal Massive Grant-Free access(NoMaGFA)scheme,which reaps the joint benefits of RA and NOMA,is proposed for asynchronous transmissions in satellite-based IoT to achieve improved system throughput and enhance the system robustness under varying traffics.Finally,we identify some important and interesting future developments for satellite-based IoT,including waveform design,transceiver design,resource allocation,and artificial intelligence-enhanced design.

关键词： Internet of things Satellite communications non-orthogonal multiple access Random access Asynchronous transmission

Joint optimization for secure ambient backscatter communication in NOMA-enabled IoT networks

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Digital Communications and Networks 2023年第1期9卷 264-269页

作者： Wali Ullah Khan Furqan Jameel Asim Ihsan Omer Waqar Manzoor Ahmed Interdisciplinary Centre for Security Reliability and Trust(SnT)/SigComUniversity of LuxembourgLuxembourg Department of Communications and Networking Aalto University02150EspooFinland Department of Communication and Information Engineering Shanghai Jiao Tong UniversityShanghai200240China Department of Engineering Thompson Rivers University(TRU)British Columbia(BC)Canada College of Computer Science and Technology Qingdao UniversityQingdao266071China

non-orthogonal multiple access(NOMA)has emerged as a novel air interface technology for massive connectivity in Sixth-Generation(6G)era.The recent integration of NOMA in Backscatter Communication(BC)has triggered significant research interest due to its applications in low-powered Internet of Things(IoT)networks.However,the link security aspect of these networks has not been well investigated.This article provides a new optimization framework for improving the physical layer security of the NOMA ambient BC system.Our system model takes into account the simultaneous operation of NOMA IoT users and the Backscatter Node(BN)in the presence of multiple EavesDroppers(EDs).The EDs in the surrounding area can overhear the communication of Base Station(BS)and BN due to the wireless broadcast transmission.Thus,the chief aim is to enhance link security by optimizing the BN reflection coefficient and BS transmit power.To gauge the performance of the proposed scheme,we also present the suboptimal NOMA and conventional orthogonal multiple access as benchmark schemes.Monte Carlo simulation results demonstrate the superiority of the NOMA BC scheme over the pure NOMA scheme without the BC and conventional orthogonal multiple access schemes in terms of system secrecy rate.

关键词： 6G non-orthogonal multiple access Ambient backscatter communication Internet-of-things Joint optimization Physical layer security