Abstract
Abstract Non-orthogonal multiple access (NOMA) has very high spectral efficiency and system capacity. NOMA has become one of the most competitive access solutions in 5G systems. In this article, the principle of NOMA is discussed first. Then, the NOMA system capacity optimisation problems are studied. Signal to interference plus noise ratio (SINR) is an important factor which affects the system capacity. The SINR of current user n is only related to the power allocated to users n+1 to N with high signal-to-noise ratio (SNR) but not interfered by users with low SNR. Therefore, a tree topology power allocation (TTPA) algorithm is introduced. When users are allocated to each layer of the tree structure, the current power allocation of each layer will not be affected by the previous layer. Through theoretical analysis, TTPA can achieve the same performance as the full search power allocation algorithm; however, its computational complexity is reduced from exponential to constant. It can be seen from the numerical simulation results that the proposed algorithm can achieve higher system capacity and has lower computational complexity.
Highlights
The generation of mobile communications is facing huge challenges, mainly in the following two aspects: on the one hand, mass mobile terminals will be connected to the mobile network
In this article, considering that the power allocation mechanism in the Non-orthogonal multiple access (NOMA) system in 5G is not clear, we study NOMA technology and its power allocation problem
The optimisation of system capacity and power allocation was researched in this article
Summary
The generation of mobile communications is facing huge challenges, mainly in the following two aspects: on the one hand, mass mobile terminals will be connected to the mobile network. In terms of further improving the spectrum efficiency and system capacity of mobile communications, non-OMA (NOMA) is a technology worthy of attention. This new technology is trying to increase the throughput by allocating the same spectrum resource to different users through non-orthogonal access methods [2]. The hybrid technology of NOMA and multiple-input multiple-output (MIMO) is discussed to enhance the system throughput Under these circumstances, the base station (BS) transmitting multiple beams equals to multi-users MIMO. User pairing scheme based on the FPA algorithm in NOMA system was studied in the literature [9].
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