Abstract
Due to the characteristic of transmitting multiplexed signals in superposed mode over the same spectrum, non-orthogonal multiple access (NOMA) technology is deemed as a promising way to improve spectral efficiency in fifth generation (5G) networks. In this paper, we develop a NOMA cooperative system based on the two-path successive relaying concept, in which the data at the source node is divided into two parallel parts and is transmitted to the destination in superposed mode via the assistance of two amplify-and-forward (AF) relays. On the condition that the transmit power of the individual nodes and the entire system are all constrained, the maximization of achievable rate is formulated as an optimization problem. Following the guidelines of Karush-Kuhn-Tucher (KKT) conditions, the dual decomposition method is adopted to obtain the closed-form expressions of the optimal power allocation. Moreover, to balance the achievable rate between two superposed signals, which is equivalent to minimizing the required spectrum bandwidth, a power allocation scheme between the superposed signals is proposed. In order to verify the effectiveness and efficiency of the proposed power allocation scheme, we conduct extensive numerical simulation on some realistic system setup. The results demonstrate that our analytical insights about the optimal power allocation are aligned with the simulation outcome.
Highlights
In wireless networks, spectrum efficiency and energy efficiency are two most important metrics to consider, as their improvement is one of the promising means to realize broadband-green communication concept
We develop a non-orthogonal multiple access (NOMA)-based two-path relay system with the full interference cancellation (FIC) concept, where a source node transmits signals to a single user under the assistance of two AF relays with half-duplex mode
We have shown the idea of a NOMA-based novel two-path relaying system, where the target information of the source node is divided into two equal streams and they are transmitted to the destination via two half-duplex AF relays in superposed mode
Summary
Spectrum efficiency and energy efficiency are two most important metrics to consider, as their improvement is one of the promising means to realize broadband-green communication concept. We develop a NOMA-based two-path relay system with the full interference cancellation (FIC) concept, where a source node transmits signals to a single user under the assistance of two AF relays with half-duplex mode. In such system, while targeting on the maximization of achievable rate and the minimization of required frequency band, the power allocation among the source and relay nodes, is formulated as an optimization problem. We assume that all the additive Gaussian noise be independent and identically distributed (i.i.d) with zero-mean and σ 2 variation
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