EE-SE Trade-off Optimization for Downlink NOMA Systems

As a potential multiple access scheme for future radio access, Non Orthogonal Multiple Access (NOMA) has been considered as an emerging radio access technique for the fifth-generation (5G) wireless communications. Green Radio (GR), which focuses on Energy Efficiency (EE), is becoming an inevitable trend for future wireless network design. Recent works have concentrated on the relationship between EE and SE and provided good thoughts into the EE-SE trade-off. In this paper, we study the EE-SE trade-off problem for NOMA systems in downlink. The trade-off problem is formulated as a non-convex optimization topic in which the main idea is to maximize the EE by imposing a satisfying minimum SE. The Quality of Service (QoS) requirement for each user is also introduced to ensure optimality. For this, an optimal power allocation is proposed. Through simulations, we demonstrate the proposed schemes efficiency in achieving a flexible trade-off between EE and SE.