Energy Efficient User Clustering, Hybrid Precoding and Power Optimization in Terahertz MIMO-NOMA Systems

• Published in: IEEE journal on selected areas in communications Vol. 38; no. 9; pp. 2074 - 2085
• Main Authors: Zhang, Haijun, Zhang, Haisen, Liu, Wei, Long, Keping, Dong, Jiangbo, Leung, Victor C. M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Clustering; Computer simulation; Convergence; Energy conversion efficiency; Hybrid power systems; hybrid precoding; imperfect SIC; Machine learning; MIMO; MIMO (control systems); MIMO communication; NOMA; Nonorthogonal multiple access; Optimization; Orthogonal Frequency Division Multiplexing; Power consumption; power optimization; Precoding; Radio frequency; Terahertz communication; Terahertz frequencies; Wireless communication
• ISSN: 0733-8716; 1558-0008
• DOI: 10.1109/JSAC.2020.3000888

Terahertz (THz) band communication has been widely studied to meet the future demand for ultra-high capacity. In addition, multi-input multi-output (MIMO) technique and non-orthogonal multiple access (NOMA) technique with multi-antenna also enable the network to carry more users and provide multiplexing gain. In this paper, we study the maximization of energy efficiency (EE) problem in THz-NOMA-MIMO systems for the first time. And the original optimization problem is divided into user clustering, hybrid precoding and power optimization. Based on channel correlation characteristics, a fast convergence scheme for user clustering in THz-NOMA-MIMO system using enhanced K-means machine learning algorithm is proposed. Considering the power consumption and implementation complexity, the hybrid precoding scheme based on the sub-connection structure is adopted. Considering the fronthaul link capacity constraint, we design a distributed alternating direction method of multipliers (ADMM) algorithm for power allocation to maximize the EE of THz-NOMA cache-enabled system with imperfect successive interference cancellation (SIC). The simulation results show that the proposed user clustering scheme can achieve faster convergence and higher EE, the design of the hybrid precoding of the sub-connection structure can achieve lower power consumption and power optimization can achieve a higher EE for the THz cache-enabled network.