A Joint Iterative Optimal Resource Allocation Algorithm for Non-Orthogonal Multi-User and Multi-Weight Opportunistic Beamforming Systems

• Published in: IEEE transactions on vehicular technology 2020-03, Vol.69 (3), p.2864-2877
• Main Authors: Sun, Wen-Bin, Yu, Qi-Yue, Guo, Ji-Chong, Meng, Wei-Xiao, Leung, Victor C. M.
• Format: Article
• Language: English
• Subjects: Algorithms; Beamforming; Complexity; Iterative methods; multi-weight OBF; non-orthogonal multiple access; Opportunistic beamforming; Resource allocation; Signal to noise ratio; Weight; Wireless communications
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2020.2965540

Opportunistic beamforming (OBF) is an attractive research topic in wireless communications, which can provide multi-user diversity with a low complexity. The conventional OBF technique requires a large number of waiting users, and cannot simultaneously support multiple users. In order to solve the mentioned problem, this paper proposes a downlink multi-user multi-weight opportunistic beamforming non-orthogonal multiple access (MW-OBF-NOMA) system. An objective function is formulated to maximize the sum spectrum efficiency (SE) of the proposed system, however, it is a non-convex issue and intractable to derive an optimal solution. To solve this non-convex issue, we divide it into two sub-optimal issues and solve them one-by-one. Based on the solutions of the two sub-optimal issues, a joint iterative resource allocation algorithm is presented. Moreover, we discuss the influences of signal-to-noise ratio (SNR) estimation, and deduce a closed-form expression of bit error ratio (BER). Numerical results show that our proposed system can simultaneously serve multiple users without extra resources, and achieve an improved sum SE with a low complexity.