Full-duplex Cooperative Non-orthogonal Multiple Access Research Articles

Power-efficient full-duplex near user with power allocation and antenna selection in NOMA-based systems

This paper proposes a power scaling (PS) technique aimed at mitigating the outage floor problem commonly encountered in multi-user full-duplex (FD) non-orthogonal multiple access (NOMA) systems. Two antenna modes denominated as adaptive antenna mode (AAM) and fixed antenna mode (FAM) are utilized in this work for L FD near users in close proximity. In addition, a combined method of selecting both antenna mode and near user integrated with PS is employed to improve the overall network performance. Moreover, a power allocation between the chosen near user and far user is considered. In the low-to-moderate power regions, by AAM and FAM, we achieve twice of full diversity gain and full diversity gain, respectively. The research presents mathematical expressions for deriving the average capacity and outage probability and supports the theoretical findings with simulation-based evidence. The results of this work show that PS method not only contributes to a greater spatial diversity but also leads to superior performance compared to traditional FD NOMA systems. Moreover, our proposed method overcomes the outage floor and capacity ceiling. Furthermore, the work can be developed to 6G massive MIMO technology in multi-user FD cooperative NOMA systems.

On the physical layer security performance of full‐duplex cooperative NOMA system with multiple eavesdroppers, imperfect SIC and hardware imperfections

AbstractIn this letter, we propose a control jammer‐assisted framework for improving the physical layer security (PLS) of full‐duplex (FD) ‐ cooperative non‐orthogonal multiple access (FD‐CNOMA) network. We derive analytical expressions for the secrecy outage probabilities (SOPs) of the users for the jammer‐assisted and the no‐jammer scenarios, considering multiple non‐colluding eavesdroppers, residual hardware impairments and imperfect successive interference cancellation conditions. It is demonstrated that the proposed jammer‐assisted framework provides significant reduction of the SOPs experienced by the downlink users in FD‐CNOMA network.

Performance Analysis of Full-Duplex Cooperative NOMA Short-Packet Communications

This paper presents the performance analysis for the two-user downlink cooperative non-orthogonal multiple access (C-NOMA) short-packet communication (SPC) over Rayleigh channels. The near user acts as a relay, which operates in full-duplex (FD) mode and employs decode-and-forward protocol, to forward the information to the far user. Two kinds of residual self-interference (RSI) models, which are modeled as being free of fading and following Rayleigh fading, are considered. We first derive the approximate closed-form expressions of average block error rate (BLER) at both users under these two RSI models. Then, simulations are provided to verify the validity of our theoretical analysis. Finally, we evaluate the BLER performance difference between long-packet and short-packet transmissions for FD C-NOMA and that between FD relaying and half-duplex (HD) relaying. The analysis and simulation results show that, for ultra-reliable and low-latency communication, we can use RSI link modeled as being free of fading to simplify the system analysis. Furthermore, compared to long-packet communication, for FD C-NOMA SPC have a narrow range of power allocation to achieve high-reliable transmission, and because BLER outperformance of FD relaying over HD relaying degrades when the RSI signal becomes strong, the optimal duplex mode for FD C-NOMA SPC is determined by the RSI signal and the target BLERs at both users.

Full Duplex Cooperative Rate Splitting Multiple Access for a MISO Broadcast Channel With Two Users

In this letter, we investigate the performance of a full-duplex (FD) cooperative rate splitting multiple access (C-RSMA) scheme in a downlink multiple-input single-output (MISO) system consisting of one base station (BS) that serves two users simultaneously. With the objective of maximizing the minimum achievable rate, we jointly optimize the BS precoding vectors, the common-stream split and the device-to-device transmit power subject to the power budget of both the BS and the relay device. As the entire problem is non-convex, we propose a low complexity algorithm based on the successive convex approximation (SCA) technique. Simulation results demonstrated that the FD C-RSMA can achieve a higher minimum achievable rate than some baseline schemes, including the FD cooperative non-orthogonal multiple access (FD C-NOMA), the half-duplex (HD) C-RSMA, RSMA and NOMA.

Joint Clustering and Power Allocation in Coordinated Multipoint Assisted C-NOMA Cellular Networks

We consider a wireless network consisting of two adjacent cells, where the joint transmission (JT) coordinated multipoint (CoMP) is established to assist the user equipments (UEs) located at the edge of each cell. In addition, full-duplex (FD) cooperative non-orthogonal-multiple-access (C-NOMA) is invoked within each cell to improve the data rates of the UEs and to assist those at the cell edge. The UEs are categorized into two groups, namely, cell-center UEs (<inline-formula> <tex-math notation="LaTeX">$CUs$ </tex-math></inline-formula>) and cell-edge UEs (<inline-formula> <tex-math notation="LaTeX">$EUs$ </tex-math></inline-formula>). The <inline-formula> <tex-math notation="LaTeX">$CUs$ </tex-math></inline-formula> are the UEs located around the center of each cell. Meanwhile, the <inline-formula> <tex-math notation="LaTeX">$EUs$ </tex-math></inline-formula> are the UEs located at the edge of each cell, where the JT-CoMP is applied since they have less distinctive received power from two cells. In this paper, a framework to jointly optimize the power control and the UEs clustering of CoMP-assisted FD C-NOMA system is formulated as an optimization problem to maximize the network sum-rate while guaranteeing the required quality-of-service of UEs. The formulated problem is a non-convex mixed-integer non-linear program that cannot be solved in a straightforward manner. To tackle this issue, the formulated problem is decomposed into an inner power allocation problem and an outer UEs clustering problem. For the inner problem, a computational-efficient solution is obtained. Meanwhile, the outer problem is reformulated as a one-to-one three-sided matching game. Then, a low-complexity near-optimal clustering algorithm is proposed. The simulation results demonstrate that 1) the optimality of the power control solution; 2) the CoMP-assisted FD C-NOMA has a superior performance compared to CoMP-assisted half-duplex (HD) C-NOMA and CoMP NOMA schemes for moderate values of self-interference. It has been also shown that the proposed solution achieves around 96.5&#x0025; of the average achievable network sum-rate of the optimal solution.

Exploiting FD/HD Cooperative-NOMA in Underlay Cognitive Hybrid Satellite-Terrestrial Networks

This paper investigates the performance of an underlay cognitive hybrid satellite-terrestrial network comprising a primary satellite source with its multiple terrestrial primary receivers and a secondary transmitter with its pre-paired users that are deployed on the ground based on a cooperative non-orthogonal multiple access (C-NOMA) scheme. Herein, the nearby NOMA user works in full-duplex (FD) mode while employing a decode-and-forward relaying strategy for improving the performance of the far-away NOMA user. Importantly, we consider the realistic assumptions of FD-based loop self-interference and NOMA-based imperfect successive interference cancellation (SIC). By exploiting the mutual interference and the pertinent hybrid channels, we analyze the performance of the secondary network in terms of outage probability (OP), ergodic sum rate, and throughput. Further, to perform a more comprehensive analysis, both perfect SIC (pSIC) and imperfect SIC (ipSIC) situations are taken into account for the FD mode and the benchmark half-duplex (HD) mode for comparison purposes. Also, we examine the asymptotic OP behaviour at a high signal-to-noise ratio (SNR) to assess the achievable diversity orders. Our results manifest that FD C-NOMA outperforms HD C-NOMA for the case of ipSIC, whereas for the case of pSIC, HD C-NOMA can outperform FD C-NOMA in the high SNR regime.

Contract Theory-Based Incentive Mechanism for Full Duplex Cooperative NOMA with SWIPT Communication Networks.

Cooperative Non-Orthogonal Multiple Access (NOMA) with Simultaneous Wireless Information and Power Transfer (SWIPT) communication can not only effectively improve the spectrum efficiency and energy efficiency of wireless networks but also extend their coverage. An important design issue is to incentivize a full duplex (FD) relaying center user to participate in the cooperative process and achieve a win–win situation for both the base station (BS) and the center user. Some private information of the center users are hidden from the BS in the network. A contract theory-based incentive mechanism under this asymmetric information scenario is applied to incentivize the center user to join the cooperative communication to maximize the BS’s benefit utility and to guarantee the center user’s expected payoff. In this work, we propose a matching theory-based Gale–Shapley algorithm to obtain the optimal strategy with low computation complexity in the multi-user pairing scenario. Simulation results indicate that the network performance of the proposed FD cooperative NOMA and SWIPT communication is much better than the conventional NOMA communication, and the benefit utility of the BS with the stable match strategy is nearly close to the multi-user pairing scenario with complete channel state information (CSI), while the center users get the satisfied expected payoffs.

Hardware Impairments Aware Full-Duplex NOMA Networks Over Rician Fading Channels

A cooperative full duplex (FD) nonorthogonal multiple access (NOMA) scheme over Rician fading channels is considered. The practical, imperfect successive interference cancellation and residual hardware impairments at transceivers are taken into account. To evaluate the performance of the considered system, the analytical approximate expressions for the outage probability and the ergodic rate of the considered system are derived, and the asymptotic performance is also explored. Simulation results manifest that the FD cooperative NOMA can improve the ergodic sum rate of the system compared to the half-duplex mode.

Full/half duplex cooperative relaying NOMA network under power splitting based SWIPT: Performance analysis and optimization

Non-orthogonal multiple access (NOMA) and full duplex (FD) relaying are two promising techniques to enhance the spectral efficiency of the fifth generation (5G) wireless networks. Simultaneous wireless information and power transfer (SWIPT) technique has recently emerged as an effective solution to improve the energy efficiency of wireless networks. This paper investigates outage and throughput performance of SWIPT enabled FD cooperative NOMA network under power splitting relaying (PSR) protocol, i.e., SWIPT enabled FD-PSR-NOMA network. We assume a single cell network consisting of a base station (BS) and two pre-paired users, i.e., a near user and a far user, where the near user acts as FD relay to assist the BS for information delivery to the far user, and power splitting (PS) technique is used at the relay for energy harvesting (EH). We derive analytical expressions for the outage probabilities experienced by the downlink users, system outage probability and delay limited system throughput under imperfect successive interference cancellation (i-SIC). We also derive analytical expressions for outage probabilities and throughput of SWIPT enabled half duplex (HD) cooperative NOMA network under PSR, i.e., SWIPT enabled HD-PSR-NOMA network. The optimal power allocation (OPA) factor at the BS and optimal power splitting (OPS) factor at the relay that independently minimizes the asymptotic system outage probabilities of SWIPT enabled FD/HD-PSR-NOMA networks are determined. Further, we explore the jointly optimal power allocation and power splitting factor that minimize the system outage probability. Furthermore, we derive analytical expression for the OPS factor that maximizes the asymptotic system throughput. We provide extensive numerical and simulation results to establish that system outage and throughput improve significantly under the proposed schemes.

Sum Rate DL/UL Performance of Co-operative NOMA Systems Over Weibull Fading Channel

This work evaluates the sum rate performance for dual user with full duplex co-operative non-orthogonal multiple access (FD-CNOMA) over Weibull fading channel environment. For this, we derived closed form expressions for sum-rate in various scenario in downlink and uplink both. One user always acts as decode and forward full duplex relay to help far users in each scenario. In the first scenario, no direct link exists between base station (BS) and far user. In second scenario, direct link exists between BS and far user. The main investigation is to study the effect of fading parameters in different channel condition on sum-rate performance. Since, Weibull Distribution (WD) has an advantage to model different fading condition using varying parameter it is more suitable to study impact of fading condition on different wireless techniques for next generation mobile cellular communication. Therefore, WD is used in this study for sum rate performance evaluation with derived expressions. Finally, simulations were conducted on MATLAB to evaluate the system performance under different fading parameters of Weibull fading channels .

Outage Performance of Downlink Full-Duplex Network-Coded Cooperative NOMA

This letter studies the impact of network-coded multiple access (NCMA) on the outage performance of full-duplex cooperative non-orthogonal multiple access (NOMA). In particular, we propose a network-coded cooperative NOMA (NC-CNOMA) strategy, under which user devices utilize physical-layer network coding (PNC) to demodulate signals with greater probability. The exact analytical expression of the outage probability is derived to evaluate the performance of the proposed scheme. The provided simulation results validate our analysis and the proposed NC-CNOMA scheme outperforms the conventional cooperative NOMA with regard to outage performance.

Ergodic Capacity and Outage Performance Analysis of Uplink Full-Duplex Cooperative NOMA System

We propose an uplink full-duplex (FD) cooperative non-orthogonal multiple access (NOMA) system, where a dedicated Full-duplex (FD) relay is used to help two uplink users transmitting information to the base station. A novel FD relay transmission mode is proposed, in which the FD relay utilizes successive interference cancellation (SIC) and self-interference cancellation to decode two users symbols at the relay receiving antenna, and the relay transmitting antenna transmits superimposed signal to the base station using superposition coding. In this paper, we also consider a more realistic scenario where self-interference cancellation is imperfect. Hence, the residual-self interference exists. Moreover, the ergodic sum rate and the outage probability of the proposed system are investigated and the accurate analytical expressions are derived. Simulation results validate that, compared with the uplink half-duplex (HD) cooperative NOMA system and the uplink HD cooperative orthogonal multiple access (OMA) system, our proposed system obtains better performance of the ergodic sum rate and outage probability in the main signal to noise ratio (SNR) regime.

On the Achievable Max-Min Rates of Cooperative Power-Domain NOMA Systems

The non-orthogonal multiple access (NOMA) schemes, where the users are allowed to share the same time-frequency resource, have recently received a major interest to meet the increasing demands for higher data rates, improved user fairness, and/or lower latency applications in future dense-user wireless networks. Moreover, the achievable user rates of NOMA schemes can be further increased through the integration of these multiple access schemes with other enabling schemes such as full-duplex user cooperative communications. In this paper, the optimization of the achievable max-min rates for full-duplex cooperative NOMA (CNOMA) schemes for the two-user scenario are re-visited and is extended to the three-user scenario where novel expressions for the optimal user cooperation power are derived for both scenarios. The obtained results shed new lights on the optimal transmit power allocation and the optimal user cooperation power allocation in CNOMA systems and the different design trade-offs in such systems.

Full-Duplex Relaying Cognitive Radio Network With Cooperative Nonorthogonal Multiple Access

This paper proposes a cooperative nonorthogonal multiple access (CNOMA) scheme in a full-duplex (FD) relaying cognitive radio network (CRN), where a primary user (PU) communicates with the base station under the assistance of a secondary user (SU), in order to sufficiently utilize both idle and underutilized spectrum resources. When the PU does not exist, the SU identifies this idle licensed spectrum band by spectrum sensing and occupies it so that the waste of spectrum hole resource is avoided. When the PU exists, it allows the SU to share its spectrum band by NOMA to further increase the spectrum efficiency. By adopting FD mode, the proposed FD CNOMA scheme not only achieves better system performance than half-duplex mode by receiving and transmitting simultaneously, but also overcomes inherent issues of conventional CRNs. To characterize the performance of the proposed scheme, expressions of exact and asymptotic ergodic rates and system throughput are worked out. Accordingly, the high signal-to-noise ratio slopes for these ergodic rates are further derived. Simulation results verify the correctness of all these derivation results. They also illustrate that FD CNOMA outperforms other cooperative benchmarks in real-world scenarios in terms of both ergodic rates and system throughput.

Virtual Full-Duplex Cooperative NOMA: Relay Selection and Interference Cancellation

In this paper, we propose a virtual full-duplex cooperative non-orthogonal multiple access (NOMA) framework for a downlink two-hop network assisted by multiple half-duplex decode–and–forward (DF) relay stations (RSs). In the proposed virtual full-duplex framework, the RSs except for a selected RS to forward the received signal suffer from inter-RS interference since both the BS and the selected RS transmit the super-imposed signal simultaneously. To address this problem, we propose an RS selection algorithm with adaptive inter-RS interference management and we mathematically attain the closed-form outage probability, which is challenging in general. In addition, we investigate diversity-multiplexing tradeoff (DMT) performance of a modified version of the proposed RS selection algorithm based on a discrete Markov chain, which adaptively resets the successive transmission. Simulation results show that the proposed RS selection algorithm outperforms the conventional cooperative NOMA algorithm in terms of both the outage probability and the DMT, which has the best performance reported in the literature.

Exploiting NOMA in D2D assisted full-duplex cooperative relaying

This paper proposes a device-to-device (D2D) enabling cellular full-duplex (FD) cooperative (DFC) protocol using non-orthogonal multiple access (NOMA) called DFC-NOMA, where an FD relay acting D2D transmitter assists in relaying a NOMA far user’s signal and transmits a D2D receiver’s signal simultaneously. The ergodic capacity, outage probability, and diversity order of DFC-NOMA are theoretically investigated under the assumption of both perfect and imperfect interference cancellation. The theoretical analysis is then validated by simulations. Both analysis and simulation results demonstrate the performance gain of DFC-NOMA over conventional FD cooperative NOMA and existing D2D aided FD NOMA.

Full-Duplex Cooperative NOMA Relaying Systems With I/Q Imbalance and Imperfect SIC

The performance of full-duplex (FD) cooperative non-orthogonal multiple access (C-NOMA) relaying systems in the presence of in-phase and quadrature-phase imbalance (IQI) and imperfect successive interference cancellation (ipSIC) is analyzed and evaluated. In particular, by considering two classes of users located far from and near to the information source, closed-form exact and analytical approximate expressions for the outage probability (OP) and ergodic sum rate (ESR), respectively, are derived. The accuracy of the analytical approach is verified by computer simulations which have shown that for both C-NOMA and equivalent OMA systems IQI has a deleterious effect on their OP and ESR performance in moderate and high signal-to-noise ratio (SNR) regions and the OP of C-NOMA is always slightly lower than that of the traditional OMA. Additionally, comparisons with equivalent half-duplex (HD) C-NOMA schemes have revealed that for the far user the FD C-NOMA scheme is less sensitive to ipSIC.

Exploiting Full-Duplex Two-Way Relay Cooperative Non-Orthogonal Multiple Access

In this paper, a novel full-duplex cooperative non-orthogonal multiple access (FD CNOMA) system is proposed, where users intend to exchange messages with the assistance of a decode-and-forward relay. To characterize the potential performance gain brought by the proposed FD CNOMA scheme, the outage probability and ergodic rate are analyzed. Specifically, the closed-form expressions for the outage probabilities, diversity orders, ergodic rates, and system throughputs in delay-limited and delay-tolerant transmission modes are derived under the realistic assumption of imperfect self-interference cancellation. Furthermore, to present the comprehensive performance evaluation, both perfect and imperfect successive interference cancellations (SICs) are taken into consideration. Simulations are performed to validate the accuracy of the derivation results and to illustrate the outstanding performance of the proposed scheme in low signal-to-noise ratio region compared with half-duplex CNOMA system and cooperative orthogonal multiple access system. Our results show that under the conditions of both perfect and imperfect SICs, outage probability floors and ergodic rate ceilings exist for the proposed FD CNOMA scheme due to the inter-user interference among superimposed NOMA signals and the residual self-interference caused by the imperfect self-interference cancellation.

Energy Efficiency Maximization Design for Full-Duplex Cooperative NOMA Systems With SWIPT

This paper investigates non-orthogonal multiple access (NOMA) system, where the near NOMA user is able to communicate with a base station (BS) directly while the far NOMA user needs to resort to a full-duplex (FD) relay. Wireless power transfer is applied to our system where the FD relay integrated with power splitting architecture can be powered wirelessly by the ambient radio signals simultaneously. Moreover, we assume that self-interference cancellation at the relay and inter-user interference cancellation at the near NOMA user are imperfect. For the purpose of maximizing the energy efficiency of the NOMA system, the power splitting ratio and transmit beamforming vectors are researched for the BS and relay with the guarantee of QoS requirements for two users. The formulated problem appears to be nonlinear fractional programming, which is highly nonconvex and the global optimality is hard to obtain. By introducing Charnes-Cooper's transformation and inner approximation method, we develop an iterative algorithm to gain the near optimal solution. The simulation results show that the proposed joint optimizing algorithm outperforms the existing scheme in terms of energy efficiency as well as the effect of SI cancellation on performance gain.

Energy-Efficient Full-Duplex Cooperative Nonorthogonal Multiple Access

The full-duplex (FD) cooperative nonorthogonal multiple access (NOMA) achieves a superior throughput over the conventional half-duplex (HD) cooperative NOMA, wherein the strong users (SUs) with good channel conditions can act as an FD relay node for the weak users with poor channel conditions. However, the energy efficiency (EE) of a cooperative NOMA may be degraded due to the additional power consumption incurred at the SUs. We are, therefore, motivated to investigate the EE maximization problem of an FD cooperative NOMA system. More importantly, we investigate the “signal-to-inference-noise ratio gap reversal” problem of cooperative NOMA systems, which imposes successive interference cancellation (SIC) performance degradation at the SUs. This problem has not been documented in the existing cooperative NOMA literature. A low-complexity algorithm is proposed for maximizing the system's EE while guaranteeing a successful SIC operation. Our numerical results show that the proposed algorithm achieves both a higher EE and throughput over the existing HD cooperative NOMA and nonadaptive FD cooperative NOMA. More importantly, the proposed scheme guarantees a successful SIC operation at the SUs.