Non-orthogonal multiple access(NOMA)is a promising technology for the next generation wireless communication networks.The benefits of this technology can be further enhanced through deployment in conjunction with mult...Non-orthogonal multiple access(NOMA)is a promising technology for the next generation wireless communication networks.The benefits of this technology can be further enhanced through deployment in conjunction with multiple-input multipleoutput(MIMO)systems.Antenna selection plays a critical role in MIMO–NOMA systems as it has the potential to significantly reduce the cost and complexity associated with radio frequency chains.This paper considers antenna selection for downlink MIMO–NOMA networks with multiple-antenna basestation(BS)and multiple-antenna user equipments(UEs).An iterative antenna selection scheme is developed for a two-user system,and to determine the initial power required for this selection scheme,a power estimation method is also proposed.The proposed algorithm is then extended to a general multiuser NOMA system.Numerical results demonstrate that the proposed antenna selection algorithm achieves near-optimal performance with much lower computational complexity in both two-user and multiuser scenarios.展开更多
Reconfigurable intelligent surface(RIS)is a novel meta-material which can form a smart radio environment by dynamically altering reflection directions of the impinging electromagnetic waves.In the prior literature,the...Reconfigurable intelligent surface(RIS)is a novel meta-material which can form a smart radio environment by dynamically altering reflection directions of the impinging electromagnetic waves.In the prior literature,the inter-RIS links which also contribute to the performance of the whole system are usually neglected when multiple RISs are deployed.In this paper we investigate a general double-RIS assisted multiple-input multiple-output(MIMO)wireless communication system under spatially correlated non line-of-sight propagation channels,where the cooperation of the double RISs is also considered.The design objective is to maximize the achievable ergodic rate based on full statistical channel state information(CSI).Specifically,we firstly present a closedform asymptotic expression for the achievable ergodic rate by utilizing replica method from statistical physics.Then a full statistical CSI-enabled optimal design is proposed which avoids high pilot training overhead compared to instantaneous CSI-enabled design.To further reduce the signal processing overhead and lower the complexity for practical realization,a common-phase scheme is proposed to design the double RISs.Simulation results show that the derived asymptotic ergodic rate is quite accurate even for small-sized antenna arrays.And the proposed optimization algorithm can achieve substantial gain at the expense of a low overhead and complexity.Furthermore,the cooperative double-RIS assisted MIMO framework is proven to achieve superior ergodic rate performance and high communication reliability under harsh propagation environment.展开更多
针对去蜂窝(cell free,CF)大规模多输入多输出(multiple-input multiple-output,MIMO)系统中存在严重的导频污染问题,提出了一种基于位置分配的贪婪导频分配功率控制算法(greedy pilot assignment based on location with pilot power c...针对去蜂窝(cell free,CF)大规模多输入多输出(multiple-input multiple-output,MIMO)系统中存在严重的导频污染问题,提出了一种基于位置分配的贪婪导频分配功率控制算法(greedy pilot assignment based on location with pilot power control,GPABL with PPC).首先,遵循相邻用户不分配相同导频序列的原则进行贪婪导频分配(greedy pilot assignment,GPA);然后,在导频分配的基础上叠加了导频功率控制,选择合理的导频功率控制系数减小信道估计的均方误差.仿真结果表明,将两种方式结合起来进行导频优化,系统的吞吐能力有所提升.展开更多
文摘双基地多输入多输出(Multiple-Input Multiple-Output, MIMO)雷达阵元故障会导致三阶观测张量中出现缺失切片数据,严重影响目标角度估计性能。为此,提出一种基于原子范数的阵元故障MIMO雷达差分共阵角度估计方法。首先,对MIMO雷达三阶观测张量进行PARAFAC分解得到收发阵列的不完整因子矩阵;然后,利用收发阵列的因子矩阵分别获得发射和接收差分共阵的导向矩阵,并利用差分共阵的冗余度对故障阵元缺失数据进行填充,从而得到等效虚拟收发阵列的虚拟因子矩阵;最后,为了填补等效虚拟阵列中的空洞,分别对等效虚拟收发阵列的虚拟因子矩阵建立原子范数约束下的低秩矩阵重构模型,并将其表述为半正定规划(Semi-definite Programming, SDP)问题,利用交替方向乘子法(Alternating Direction Method of Multipliers, ADMM)求解该矩阵重构模型。仿真结果表明,所提方法可以有效重构出不完整因子矩阵中的缺失数据,从而改善MIMO雷达阵元故障下的角度估计性能。
文摘超大规模多输入多输出(Extremely Large-scale Multiple-Input Multiple-Output,XL-MIMO)系统的信道通常以瑞利距离为边界分为近场信道和远场信道,混合场信道模型用路径数比例因子将球面波前的近场信道模型和平面波前的远场信道模型叠加,致使信道参数维数剧增,信道估计的导频开销极大,且由于离格能量泄露难以获取精确信道参数向量的稀疏度。针对这类通信系统的信道估计问题,为降低导频开销并提高计算效率,分析远场的角度域稀疏信道表示模型和近场的极化域稀疏信道表示模型,在稀疏信号恢复框架下将估计问题转化为L1范数优化问题,提出基于交替方向乘子法(Alternating Direction Method of Multiplier,ADMM)的混合场稀疏信道估计算法,并提出一种改进的ADMM算法,将拉格朗日乘子更新用两步对称的方式迭代计算,使得算法的收敛速度更快,计算效率更高。这两种算法可摆脱常规正交匹配追踪(Orthogonal Matching Pursuit,OMP)算法对信道稀疏度的依赖,相比于OMP算法在估计精度方面有较大提升。
文摘Non-orthogonal multiple access(NOMA)is a promising technology for the next generation wireless communication networks.The benefits of this technology can be further enhanced through deployment in conjunction with multiple-input multipleoutput(MIMO)systems.Antenna selection plays a critical role in MIMO–NOMA systems as it has the potential to significantly reduce the cost and complexity associated with radio frequency chains.This paper considers antenna selection for downlink MIMO–NOMA networks with multiple-antenna basestation(BS)and multiple-antenna user equipments(UEs).An iterative antenna selection scheme is developed for a two-user system,and to determine the initial power required for this selection scheme,a power estimation method is also proposed.The proposed algorithm is then extended to a general multiuser NOMA system.Numerical results demonstrate that the proposed antenna selection algorithm achieves near-optimal performance with much lower computational complexity in both two-user and multiuser scenarios.
基金supported in part by the Xi’an Jiaotong-Liverpool University(XJTLU)Research Development Fund(2024–2027)under Grant RDF-23-02-010supported in part by the Guangdong Basic and Applied Basic Research Foundation under Grant 2023A1515110732+5 种基金supported in part by the National Natural Science Foundation of China(NSFC)under Grant 62071247supported in part by the Science and Technology Development Fund,Macao,China SAR under Grants 0087/2022/AFJ and 001/2024/SKLin part by the National Natural Science Foundation of China under Grant 62261160650in part by the Research Committee of University of Macao,Macao SAR,China under Grants MYRG-GRG2023-00116-FST-UMDF and MYRG2020-00095-FSTsupported in part by the NSFC under Grant 62261160576 and 62301148in part by the Fundamental Research Funds for the Central Universities under Grant 2242023K5003.
文摘Reconfigurable intelligent surface(RIS)is a novel meta-material which can form a smart radio environment by dynamically altering reflection directions of the impinging electromagnetic waves.In the prior literature,the inter-RIS links which also contribute to the performance of the whole system are usually neglected when multiple RISs are deployed.In this paper we investigate a general double-RIS assisted multiple-input multiple-output(MIMO)wireless communication system under spatially correlated non line-of-sight propagation channels,where the cooperation of the double RISs is also considered.The design objective is to maximize the achievable ergodic rate based on full statistical channel state information(CSI).Specifically,we firstly present a closedform asymptotic expression for the achievable ergodic rate by utilizing replica method from statistical physics.Then a full statistical CSI-enabled optimal design is proposed which avoids high pilot training overhead compared to instantaneous CSI-enabled design.To further reduce the signal processing overhead and lower the complexity for practical realization,a common-phase scheme is proposed to design the double RISs.Simulation results show that the derived asymptotic ergodic rate is quite accurate even for small-sized antenna arrays.And the proposed optimization algorithm can achieve substantial gain at the expense of a low overhead and complexity.Furthermore,the cooperative double-RIS assisted MIMO framework is proven to achieve superior ergodic rate performance and high communication reliability under harsh propagation environment.
文摘针对去蜂窝(cell free,CF)大规模多输入多输出(multiple-input multiple-output,MIMO)系统中存在严重的导频污染问题,提出了一种基于位置分配的贪婪导频分配功率控制算法(greedy pilot assignment based on location with pilot power control,GPABL with PPC).首先,遵循相邻用户不分配相同导频序列的原则进行贪婪导频分配(greedy pilot assignment,GPA);然后,在导频分配的基础上叠加了导频功率控制,选择合理的导频功率控制系数减小信道估计的均方误差.仿真结果表明,将两种方式结合起来进行导频优化,系统的吞吐能力有所提升.
