Abstract
In this article, we introduce a small-cell network operating in the context of heterogeneous cellular networks for both downlink (DL) and uplink (UL) by deploying three techniques of full-duplex transmission mode, energy harvesting, and power domain-based non-orthogonal multiple access (NOMA) schemes. Compared to the conventional half-duplex orthogonal multiple access (OMA) scheme that has been widely implemented in current wireless communication systems, the full-duplex (FD) NOMA relying on energy harvesting scheme has a great potential to further enhance the system performance in terms of connectivity capability, spectral efficiency and outage performance. In the proposed two-user small-cell relying on NOMA scheme, the small-cell base station first transfers an energy-bearing signal to serve the two users in the DL phase. Later, an energy harvesting technique is proceeded to encourage the strong user and the weak user to transmit their messages in the UL phase in a FD manner. However, one major challenge related to the FD strategy is the self-interference signal due to a signal leakage from the terminal’s output to the input. Besides that, the interference from macro-cell users is also main reason of degradation of the system performance. In this article, we derive analytical expressions to describe the system’s performance in terms of the outage probability and throughput. Moreover, extensive numerical simulations are performed to compare and highlight the performance of the proposed small-cell network with several practical scenarios.
Highlights
Non-orthogonal multiple access (NOMA) technique has been recently investigated as one of the candidate technologies to be implemented in the generation of wireless networks (e.g., 5G) [1]–[4]
NUMERICAL RESULTS we evaluate the performance of the proposed system with both numerical analysis and extensive simulations
In this article, an energy harvesting-based PDMA transmission scheme is studied in UL and DL phases, in which the harvested power obtained in the DL phase is reused for signal processing in the UL phase
Summary
Non-orthogonal multiple access (NOMA) technique has been recently investigated as one of the candidate technologies to be implemented in the generation of wireless networks (e.g., 5G) [1]–[4]. SYSTEM ARCHITECTURE Fig. 1 shows the schematic system model of a NOMA-based HetNet system where both the uplink and the downlink of small-cell network are enabled by the energy harvesting (EH) capability This system consists of a small-cell base station (SBS) equipped with two antennas that intend to simultaneously communicate with other users at the transmit and receive sides. Where η, 0 ≤ η ≤ 1 stands for the energy conversion efficiency at the user, α is the time splitting factor in TSR protocol, and T is the time block of the considered frame Such harvested powers at U1, U2 are reused to serve the UL phase in small-cell network. Before calculating the outage metric for the described system, we derive the expression for the signal to noise ratio at each user
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