Optimal Power and Resource Allocation for Transmit Power Minimization in OFDMA-based NOMA Networks

Abstract

In this article, we address the problem of optimal joint power and resource allocation when Non-Orthogonal Multiple Access (NOMA) and Orthogonal Frequency Multiple Access (OFDMA) are combined for a hybrid downlink multiple access. First, an optimal solution of joint power and resource allocation minimizing the transmit power consumption, is obtained by rewriting the original optimization problem into an equivalent convex one and then by solving it by means of the well-known interior-point method. Second, we analyze the properties of the optimum, which are twofold; we show that at the optimum, the order of the users is preserved from one channel to another. Then, we derive a closed-form expression for the optimal power allocation in the particular case where all users have positive non-zero transmit powers in all channels.

Energy-efficient opportunistic multi-carrier NOMA-based resource allocation for beyond 5G (B5G) networks

“…Therefore, several MA techniques have been proposed to handle the access issues of CR-based future wireless networks, such as orthogonal frequency division multiple access (OFDMA) [13], space domain multiple access (SDMA) [14], non-orthogonal multiple access (NOMA), and the hybrid MA techniques. Specifically, the combination of power-domain NOMA and OFDMA, referred to as hybrid OFDMA-NOMA, has been recently considered as a promising technique to support the massive connectivity of the CR-based future networks [15], [16]. On one hand, the integration between NOMA and OFDMA offers an additional degree of freedom as the power and frequency domains are utilized to serve a larger number of users [15] [16].…”

“…Specifically, the combination of power-domain NOMA and OFDMA, referred to as hybrid OFDMA-NOMA, has been recently considered as a promising technique to support the massive connectivity of the CR-based future networks [15], [16]. On one hand, the integration between NOMA and OFDMA offers an additional degree of freedom as the power and frequency domains are utilized to serve a larger number of users [15] [16]. On the other hand, due to the computational complexity of employing SIC in dense networks, employing NOMA alone introduces several practical challenges [16].…”

“…On one hand, the integration between NOMA and OFDMA offers an additional degree of freedom as the power and frequency domains are utilized to serve a larger number of users [15] [16]. On the other hand, due to the computational complexity of employing SIC in dense networks, employing NOMA alone introduces several practical challenges [16]. With the hybrid OFDMA-NOMA system, NOMA is only exploited to serve a few users within each cluster (i.e., sub-band), which overcomes the practical challenges of employing SIC.…”

Downlink Multi-Carrier NOMA With Opportunistic Bandwidth Allocations

“…To address this performance degradation, bandwidth and power allocations need to be jointly considered to enhance the performance of the MC-NOMA systems. In fact, the works in the literature consider equal bandwidth allocation, including [20], [21], and [22]. Motivated by this, we propose a sumrate maximization (SRM) based resource allocation technique for a downlink MC-NOMA system with opportunistic bandwidth allocation.…”