Abstract
This paper considers a non-orthogonal multiple access (NOMA) downlink network, where a hybrid of NOMA and beamforming designs is developed to enhance the channel capacity. We aim to improve the system performance in terms of rate fairness and power consumption. Hence, a multi-objective problem with a joint optimization of user equipment pairing, power control, and quality-of-service requirements is addressed. To efficiently solve the problem, we propose two low-complexity algorithms based on the inner-approximation method, with the first algorithm using the relaxation method and the second one using graph theory. Numerical results are provided to demonstrate the effectiveness of the two proposed algorithms in comparison with the exhaustive search and existing methods.
Highlights
Non-orthogonal multiple access (NOMA) can be considered to be a promising multiple access technology for fifth-generation networks for accommodating the rapid growth of data traffic [1,2,3,4]
The base station (BS) is located at the center of the cell, whereas the user equipment (UE) are uniformly distributed within radius R from the cell center
We studied a hybrid of NOMA and conventional beamforming design, where a dynamic pairing technique was investigated with two arbitrary UEs in a cell that can be paired together
Summary
Non-orthogonal multiple access (NOMA) can be considered to be a promising multiple access technology for fifth-generation networks for accommodating the rapid growth of data traffic [1,2,3,4]. NOMA allows user equipment (UE) to share the same time-frequency resource; the spectral efficiency (SE) and energy efficiency (EE) are improved. The NOMA technique is classified into two main categories: the power domain [5] and code domain [6]. We focus power-domain NOMA, referred to as NOMA for convenience. The key idea of power-domain NOMA is to allocate a higher power to the UE with poorer channel gain. A UE with a strong channel gain is equipped with successive interference cancellation (SIC) to remove the signal intended to the UE with poorer channel gain before decoding its own signal [5,7]
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