关键词: 关键词: 非正交多址, 认知MIMO, 分簇, 功率分配, Lagrange函数, KKT条件

Abstract: Abstract: Concerning the demand of large capacity and high spectrum utilization for future mobile communication system, a method for optimizing the capacity of secondary users in MIMO cognitive networks based on Non-orthogonal multiple access (NOMA) is proposed. Firstly, the transmitted signals are pre-coded, and then the cognitive users were clustered according to the channel gains. And secondly, the power allocation was performed by the users after clustering. Finally, the NP-hard multi-cluster objective function was transformed into the capacity of each sub-cluster, and meanwhile, the secondary users’ Quality of service (QoS) and the requirement of Successive interference cancellation (SIC) were being taken into account, and the optimal power allocation coefficient, which is constant between 0 and 1, was solved by using Lagrange function and Karush-Kuhn-Tucker (KKT) conditions. Simulation shows that the proposed scheme outperforms the average power allocation method, and when the channel quality is poor, the secondary user system capacity is significantly improved compared with the MIMO cognitive based on orthogonal multiple access.

Key words: Keywords: Non-orthogonal multiple access (NOMA), MIMO cognitive, clustering, power allocation, Lagrange function, Karush-Kuhn-Tucker conditions