Jul 2026· Nigerian Journal of Technology· 0 citations· 19 references
TL;DR
Simulation results demonstrate that the APS NOMA scheme outperforms both the FPS NOMA and Orthogonal Multiple Access schemes, reducing OP significantly across a range of SNRs, making it highly effective for reliable and energy-efficient communication in future wireless networks.
Abstract
The amalgamation of cooperative Non-Orthogonal Multiple Access (NOMA) with Simultaneous Wireless Information and Power Transfer (SWIPT) is a promising technology for addressing energy bottlenecks and extending the lifetime of wireless networks. The traditional Fixed Power Splitting (FPS) is the most widely adopted protocol in SWIPT-assisted cooperative NOMA systems due to its simplicity and ease of implementation. However, the fixed nature of its Power Splitting (PS) ratio makes it inefficient under dynamic wireless channel environments, leading to insufficient Energy Harvesting (EH) and reduced decoding capability, as it cannot adapt to fluctuating channel conditions. This study proposes an Adaptive Power Splitting (APS) protocol at the near user, where the PS ratio is dynamically adjusted in accordance with the instantaneous channel condition. This work considered a system model that consists of a single source, a near user acting as a Decode-and-Forward (DF) relay, and a far user. The APS protocol enables the near user to allocate energy for simultaneous EH and Information Decoding (ID). Closed-form expressions are derived for the Outage Probabilities (OPs) of the users under Rayleigh fading channels. Numerical evaluations are carried out to analyze the system outage performance in terms of Signal-to-Noise Ratio (SNR), energy conversion efficiency, user distance, PS, and Power Allocation (PA) ratio. Simulation results demonstrate that the APS NOMA scheme outperforms both the FPS NOMA and Orthogonal Multiple Access (OMA) schemes, reducing OP significantly across a range of SNRs, making it highly effective for reliable and energy-efficient communication in future wireless networks.
With the increasing demand for efficient wireless communication services, researchers are actively seeking innovative solutions to optimize spectrum utilization. Two promising technologies, cognitive radio and non-orthogonal multiple access (CR-NOMA), have emerged as key enablers for next-generation wireless communication. By harnessing the available radio frequency spectrum, devices can cooperatively connect and communicate more efficiently, while also gathering energy to support green communication.
This study investigates the uplink simultaneous wireless power and information transfer (SWIPT) using a CR-NOMA system over Rayleigh fading channel, focusing on energy harvesting at the secondary transmitter (ST) as a cooperation node. Here, primary/secondary receivers (PR/SR) communicate with the ST, during first phase, which then utilizes the harvested power to transmit the primary data to the primary transmitter. This paper enhances the proposed system cell-edge user performance and derives analytical frameworks for outage probability, throughput, and ergodic capacity of PR, SR, respectively. Additionally, our results determine the optimal power allocation scheme to enhance the performance of PR/SR signals.
In this paper, we consider a coexisting network of cellular transmission and device-to-device (D2D) communication, in which BS wants to communicate with far user, meanwhile, a D2D source desires to transmit information to a D2D destination. However, due to heavy shadowing or severe path loss, their direct links are not available. To cope with this problem, a relay is employed to assist the involved transmission. For such a relay-assisted spectrum sharing network, two transmission schemes are designed, i.e., multiple access broadcast NOMA (M-NOMA) scheme and time division broadcast NOMA (T-NOMA) scheme. For each scheme, we first perform power optimization to minimize the outage probability (OP) of D2D communication under the quality of service (QoS) constraint of cellular transmission. Based on the optimization results, we derive the OPs for both cellular and D2D signals. To gain more insights, the asymptotic OPs and the average throughput for both schemes are provided as well. On this basis, we further propose a more superior hybrid M/T-NOMA cognitive communication scheme, in which the system will adaptively select the one with higher system throughput between M-NOMA and T-NOMA as the final transmission scheme. Simulation results validate the accuracy of our analyses, and reveal the performance gain of our schemes over the benchmark schemes.
Yafang Zhang, Ye Tian, Haixia Li et al.· Scientific Reports· 0 citations
This paper proposes a joint transmit antenna selection (TAS) and selection combining (SC)-assisted multi-hop decode-and-forward (DF) scheme employing power-domain non-orthogonal multiple access (PD-NOMA). In the proposed protocol, a source transmits its data to a destination via a preestablished multi-hop route. TAS/SC is applied at each hop to enhance transmission reliability. Meanwhile, PD-NOMA is utilized to simultaneously transmit the source data and the data of an additional node that is not part of the source-destination route. We evaluate the end-to-end (e2e) outage probability (OPe2e) and system throughput (TP-e2e) of the proposed scheme through both analytical derivations and simulations over Rayleigh fading channels. The results show that the proposed scheme achieves the same diversity gain as the conventional TAS/SC-assisted multi-hop DF scheme without PD-NOMA. In addition, at high transmit signal-to-noise ratio (SNR) regions, the proposed scheme provides a significantly higher multiplexing gain.
Quang Minh Pham, Dat Dinh Tran, Le Thi Ngoc Diep et al.· IEEE Jordan Conference on Ap...· 0 citations
To achieve a full spatial coverage and higher spectral efficiency for the future sixth generation (6G) wireless networks, simultaneous transmission and reflection reconfigurable intelligent surfaces (STAR-RISs) has been proposed as a technology solution. The outage and diversity performance of STAR-RIS-assisted rate-splitting multiple access (RSMA) is investigated on Nakagami-m fading channels. RSMA systems dynamically control the interference by splitting the shared and private streams to improve the reliability of the transmission system under different channel conditions. The analytical frameworks are established for the composite STAR-RIS channels: central limit theorem model for the case of large number of elements, curve-fitting model for the moderate number of elements and M-Fold Convolution model for the case of high signal to noise ratio diversity assessment. The energy-splitting (ES), mode-switching (MS), and time-switching (TS) STAR-RIS protocols are studied and closed-form formulas for outage probability are derived for the three protocols. The results show that increasing the number of STAR-RIS elements from 20 to 40 significantly improves the outage performance, yielding several orders of magnitude reduction in outage probability due to enhanced beamforming gain and spatial diversity. In addition, the reduced order of the MS protocol is mMk due to partial allocation of elements, and the ES/TS protocol has a diversity order of mM. It is found that the OP of the reflecting user is less than 10−6 at approximately 115 dB for M = 40, which demonstrates the effectiveness of the STAR-RIS Assisted RSMA systems in improving the reliability, spatial diversity and interference management in the future 6G wireless communication systems.
Shahnaz Fatima, B. P. Chapa, Mahesh Babu Ammisetty et al.· Engineering Research Express· 0 citations
Rate-Splitting Multiple Access (RSMA) has emerged as a robust interference management strategy for future wireless networks. This paper investigates the performance of a hierarchical RSMA scheme in the downlink of a multi-antenna system, designed to efficiently serve clustered user deployments. We derive exact and asymptotic closed-form expressions for the outage probability of users under Nakagami- $m$ fading channels, considering a two-layer message splitting architecture (systemcommon, group-common, and private streams). Furthermore, to ensure fairness and reliability, we formulate a min-max power allocation problem to minimize the worst-case outage probability among users. A Geometric Programming-based algorithm is proposed to solve the resulting non-convex optimization problem. The numerical results validate the theoretical analysis and demonstrate the impact of different strategies for using this model, such as the number of users per group, user allocation strategies, and the number of base station transmit antennas.
R. P. De Souza, E. Olivo· International Mediterranean...· 0 citations
This paper studies a cooperative wireless system in which a single-antenna base station (BS) communicates with a destination user (U) via a half-duplex energy-harvesting amplify-and-forward relay, while the direct BS–U link is unavailable. The destination (U) is equipped with a fluid antenna system (FAS) comprising multiple closely spaced receive ports, enabling spatial reconfigurability through instantaneous port selection. A power-splitting architecture is adopted at the relay to support simultaneous energy harvesting and information forwarding. All wireless links are modeled as flat Rayleigh fading, and the spatial correlation among the FAS ports is explicitly incorporated. To analytically characterize the impact of correlated port selection, a Gaussian copula framework is employed to model the joint distribution of the FAS-channel power gains. Exact integral expressions for the cumulative distribution function of the end-to-end signal-to-noise ratio are derived, from which the outage probability is obtained. For the special case of uncorrelated FAS ports, closed-form expressions are further developed using order statistics and special functions. In addition, asymptotic analysis is carried out to provide further insight into system performance in the high-signal-to-noise-ratio region. Numerical and Monte Carlo simulation results validate the analytical derivations and demonstrate that FAS-based receiver selection yields significant gains in outage performance, even in the presence of strong spatial correlation and energy-harvesting constraints.