Full-duplex Non-orthogonal Multiple Access Systems Research Articles

WMMSE Resource Allocation for FD-NOMA

Resource allocation in interference-limited systems is a key enabler for beyond 5G (B5G) technologies, such as multi-carrier full duplex non-orthogonal multiple access (FD-NOMA). In FD-NOMA systems resource allocation is a computation-intensive non-convex problem due to the presence of strong interference and the integrality condition on channel allocation. In this letter, we propose an iterative algorithm based on the combination of channel and power allocations aimed at the minimization of the weighted mean square error, which converges to a feasible allocation of the original problem. Experimental results show that the proposed algorithm has lower complexity than other state-of-the-art solutions for the same problem. Moreover, the presented results assess the validity of our approach showing performance close to the theoretical optimum.

Energy Efficiency Maximization of Full-Duplex NOMA Systems With Improper Gaussian Signaling Under Imperfect Self-Interference Cancellation

This work addresses the energy efficiency maximization for a downlink cooperative full-duplex non-orthogonal multiple access (FD-NOMA) system in the presence of imperfect self-interference cancellation. We consider the case where users adopt improper Gaussian signaling (IGS) for their transmission and consequently derive the achievable rate of each link in the cooperative system. We jointly optimize the power allocation at the base-station and the IGS circularity coefficients of the cooperative IGS-based FD-NOMA system to maximize its energy efficiency subject to quality-of-service (QoS) requirements. Furthermore, improper constellation diagrams are designed using the predefined optimized IGS coefficients to study the impact of IGS on bit error rate performance. Simulation results demonstrate considerable energy efficiency performance gain of IGS-based FD-NOMA system over its proper Gaussian signaling (PGS)-based FD-NOMA counterpart under residual interference from imperfect self interference cancellation.

Energy Efficiency Maximization for UAV-Assisted Full-Duplex NOMA System: User Clustering and Resource Allocation

In this paper, the problem of energy efficiency maximization of an unmanned-aerial-vehicle (UAV)-assisted full-duplex non-orthogonal-multiple-access (FD-NOMA) system is investigated. In order to reduce the interference among users in the considered system, we first propose a novel and less complex adaptive-geometric distribution (AGD) which adaptively maintain equal cluster size and allocate resource optimally among the users. Later, we formulate an optimization problem of energy efficiency maximization subject to the transmit power budget at the UAV for downlink (DL) users and for each uplink (UL) user and UAV placement. To transform the non-convex problem into convex one, we decouple the original optimization problem into different sub-problems in which the problems of power allocation and UAV placement are alternatively solved using Dinkelbach’s algorithm with successive convex approximation (SCA) and particle swarm optimization (PSO), respectively. Later, the unified solution for optimal power allocation and UAV placement is proposed based on block-coordinate descent (BCD) algorithm. Extensive simulation results validate the superiority of the proposed AGD clustering based proposed algorithm for UAV-assisted FD-NOMA system over the conventional clustering and other orthogonal schemes.

Impacts of relay and direct links at destinations in full-duplex non-orthogonal multiple access system

In this study, one of effective methods of multiple access, namely non-orthogonal multiple access (NOMA), is investigated. Such NOMA scheme can be worked with signal processing at downlink side. As such, the base station sends mixed signals of two signals to destinations. A near user could be a relay to forward the signal to the distant user by leveraging benefits of full-duplex mode which allows relay to transmit and receive signals in the same time. For simple analysis, the two-user approach and fixed power allocation factors are implemented. We also derive formulas of the outage probability of two users (near-user and far-user) to indicate fairness and emphasize the role of the near user as a relay. This considered NOMA system adopts transmission with Nakagami-m fading channel. As a further metric, throughput is considered under the impacts of key system parameters. The transmit signal-to-noise ratio (SNR) at the base station make influences the performance of two users significantly as observation indicated in our simulation results. These results are confirmed by matching Monte-Carlo with the theoretical simulations.

Impacts of relay and direct links at destinations in full-duplex non-orthogonal multiple access system

Impacts of relay and direct links at destinations in full-duplex non-orthogonal multiple access system

Performance analysis of downlink NOMA relying energy harvesting and full-duplex

This paper considers the implementation of wireless power transfer scheme to non-orthogonal multiple access (NOMA) network at downlink. The single antenna power beacon (PB) provide capability of wireless charge to two NOMA users. In addition, full-duplex (FD) scheme is employed for two users. Outage probabilities related to system performance are evaluated in the scenario of the multi-antenna base station. Improved performance can be achieved since multi-antenna, energy harvesting capability. In particular, expressions of outage performance are derived in this system model to help to forward to serve far NOMA users. As the main advantage, NOMA and full-duplex schemes are two advantages and such a system is deployed to enhance the spectral efficiency. Our simulation results will indicate that main parameters such as a power allocation strategy, energy harvesting time, self-interference factor are the main impacts on considered system. The correct derived expressions are presented by matching Monte-Carlo simulation curves and analytical curves in numerical result section. As our main results, FD NOMA system corresponding the first user and the second user exhibits better than OMA 30% and 25% respectively when SNR at the source is 30 dB.

Joint UL/DL Resource Allocation for UAV-Aided Full-Duplex NOMA Communications

This paper proposes an unmanned aerial vehicle (UAV)-aided full-duplex non-orthogonal multiple access (FD-NOMA) method to improve spectrum efficiency. Here, UAV is utilized to partially relay uplink data and achieve channel differentiation. Successive interference cancellation algorithm is used to eliminate the interference from different directions in FD-NOMA systems. Firstly, a joint optimization problem is formulated for the uplink and downlink resource allocation of transceivers and UAV relay. The receiver determination is performed using an access-priority method. Based on the results of the receiver determination, the initial power of ground users (GUs), UAV, and base station is calculated. According to the minimum sum of the uplink transmission power, the Hungarian algorithm is utilized to pair the users. Secondly, the subchannels are assigned to the paired GUs and the UAV by a message-passing algorithm. Finally, the transmission power of the GUs and the UAV is jointly fine-tuned using the proposed access control methods. Simulation results confirm that the proposed method achieves higher performance than state-of-the-art orthogonal frequency division multiple-access method in terms of spectrum efficiency, energy efficiency, and access ratio of the ground users.

On the performance of physical layer security in virtual full-duplex non-orthogonal multiple access system

This paper investigates physical layer security analysis of cooperative non-orthogonal multiple access (NOMA) communication system. A virtual full-duplex (VFD) relaying scheme with an untrusted amplify-and-forward (AF) half-duplex (HD) relay and a trusted decode-and-forward (DF) HD relay is used in this system to improve the spectral efficiency. In order to prevent the untrusted relay from eavesdropping, a simple and practical cooperative jamming scheme is designed to confuse the untrusted relay. The exact expressions of effective secrecy throughput (EST) for NOMA users and approximate expression of EST for non-NOMA user are derived. All theoretical results are validated by numerical simulations which demonstrate that the proposed VFD-NOMA scheme is superior to existing HD-NOMA scheme in cooperative system and jamming plays an important role for obtaining acceptable EST. In addition, simulation results shows that the best secrecy performance highly depends on the system parameters such as transmit powers and jamming signal power.

User scheduling for full‐duplex non‐orthogonal multiple access systems with reconfiguration antennas

As the promising technologies for providing higher network throughput, full-duplex (FD) communications and non-orthogonal multiple access (NOMA) have attracted wide attention in recent years. In this study, the authors propose a user scheduling algorithm for the full-duplex non-orthogonal multiple access system (FD-NOMA) where an FD base station equipped with a pair of reconfigurable antennas serves multiple half-duplex downlink (DL) and uplink (UL) users simultaneously. Firstly, they formulate a user scheduling problem to maximise the sum rate of the FD-NOMA system. Then, they eliminate the inter-user interference from caused by the UL users to the DL users through the blind interference alignment based on reconfigurable antennas and decouple the user scheduling problem into a DL user scheduling problem and a UL user scheduling problem. Next, for the DL and UL user scheduling subproblems, they pair the users aligned with the same directions based on the channel correlation metric. Finally, they employ the exhausting search and iterative power allocation algorithm to solve the subproblems. Simulation results show that the proposed FD-NOMA system can achieve up to 233 of gain in the average sum rate compared with the existing baseline schemes.

Performance of a Non-Orthogonal Multiple Access System With Full-Duplex Relaying

In this letter, we study a power-domain non-orthogonal multiple access (NOMA) system in which a base station (BS) superimposes the transmit signals to the users. To enhance spectral efficiency and link reliability for the far-distance user, a full-duplex (FD) relay assists the BS while the near-distance user is reached over the direct link. For this setting, we analyze outage probability and sum rate of the NOMA system over Nakagami- $m$ fading with integer fading severity parameter $m$ . Numerical results are provided for outage probability and sum rate to show the effect of system parameters on the performance of the FD NOMA system over Nakagami- $m$ fading.