Non-orthogonal multiple access (NOMA) and energy harvesting (EH) are combined to introduce a dual-hop wireless sensor system. In particular, this paper considers a novel EH protocol based on time power switching-based relaying (TPSR) architecture for amplify-and-forward (AF) mode. We introduce a novel system model presenting wireless network with impacts of energy harvesting fractions and derive analytical expressions for outage probability and ergodic rate for the information transmission link. It confirmed that the right selection of power allocation for NOMA users can be performed to obtain optimal outage and ergodic capacity performance. Theoretical results show that, in comparison with the conventional solutions, the proposed model can achieve acceptable outage performance for sufficiently small threshold signal to noise ratio (SNR) with condition of controlling time switching fractions and power splitting fractions appropriately in considered TPSR protocol. We also examine the impacts of transmitting power at source, transmission rate, the other key parameters of TPSR to outage, and ergodic performance. Simulation results are presented to corroborate the proposed system.

In this paper, we investigate the performance of a secondary network in a cognitive radio network employing a non-orthogonal multiple access (NOMA) scheme to form a CR-NOMA system serving many destination users. In the secondary network of our proposed system, a device-to-device (D2D) scheme is deployed to further provide the signal transmission at a close distance of NOMA users in downlink, and such performance is evaluated under the situation of interference reception from the primary network. An outage performance gap exists among these NOMA users since different power allocation factors are assigned to the different destinations. Unlike existing NOMA schemes that consider fixed power allocation factors, which are not optimal in terms of outage performance, our proposed paradigm exhibits optimal outage in the scenario of D2D transmission. In particular, the outage performances in two kinds of schemes in term of existence of D2D link are further achieved. Simulation results validate the analytical expressions, and show the advantage of each scheme in the proposed CR-NOMA system based on outage performance and throughput.

This paper studies the wireless systems by implementing the full-duplex (FD) unmanned aerial vehicle (UAV) relay to allow two nearby base stations joint communicate to distant users. The nonorthogonal multiple access (NOMA) assisted networks and design of multiple-antenna users are considered in order to improve the users' performance. To overcome obstacles in transmission environment, such a model of the uplink (UL) and the downlink (DL) relying on UAV relay is suitable to forward signals to far users. Moreover, practical scenario of imperfect successive interference cancellation (SIC) at each receiver is considered as main reason of degraded performance. To evaluate specific performance metric, we derive the closed-form expressions of outage probability. In addition, the throughput in delay-limited transmission mode of UAV relay assisted UL/DL NOMA system is also considered thoroughly. The derivations and results showed that the higher number of antennas at users could effectively improve the system throughput and reduce the outage probability. The numerical simulation results further indicate the effectiveness of the proposed system and the correctness of theoretical analysis. INDEX TERMS Non-orthogonal Multiple Access, Unmanned Aerial Vehicle, outage probability, throughput, full-duplex, imperfect SIC.

No abstract

In this study, we deploy design and performance analysis in new system model using a relaying model, energy harvesting, and non-orthogonal multi-access (NOMA) network. It is called such topology as wireless powered NOMA relaying (WPNR). In the proposed model, NOMA will be investigated in two cases including single successive interference cancellation (SIC) and dual SIC. Moreover, the simultaneous wireless information and power transfer (SWIPT) technology can be employed to feed energy to relays who intend to serve far NOMA users. In particular, exact outage probability expressions are provided to performance evaluation. The results from the simulations are used to demonstrate the outage performance of the proposed model in comparison with the current models and to verify correct of derived expressions.

Non-orthogonal multiple access (NOMA) and ambient backscatter communication are two promising techniques recommended for the fifth generation wireless network. This work combines these approaches to propose a backscatter NOMA system, which incorporates a backscatter device together with a downlink NOMA. Such NOMA employs the base station equipped with multiple antennas. To evaluate the performance of backscatter NOMA, the expressions of the outage probabilities are derived. Finally, the numerical results are provided to verify the theoretical analysis. Introduction: Recently, considering as an effective solution to accommodate the data traffic in fifth generation (5G) networks, non-orthogonal multiple access (NOMA) is proposed due to its spectrum-efficiency and has become an emerging technique in both academia and industry. In particular, novel multiple access (MA) techniques are deployed together with millimetre wave, massive MIMO and heterogeneous networks to significantly contribute to implement 5G networks [1]. Driven by these techniques to increase both user access and system capacity, NOMA has been proposed as one of the favourable technologies for the MA scheme [2, 3]. By allocating radio resources (i.e. time/ frequency/code) under dissimilar power levels, NOMA exhibits a new concept to serve more multiple NOMA users in bandwidth efficiency circumstance. More specifically, ambient backscatter communication (AmBC) is emerging as a spectrum-and power-efficient technology [4]. Ambient RF source, backscatter device (BD), and reader are considered as the main components in the AmBC system. In addition, the OFDM system is considered in terms of the capacity for AmBC [5]. The authors of [6, 7] studied transceiver design for AmBC. The comparable performance can be achieved to exhibit the optimal detector with perfect channel state information under the same conditions in terms of BER performance [6, 7]. To provide massive BD connections, the NOMA scheme can be employed [8]. In this Letter, motivated by a novel idea from [8], we propose a multiple antenna base station (BS) in NOMA to serve two far users. The received signal and related outage performance are derived to highlight advantages of such architecture.

In this paper, we study two transmission scenarios for the base station (BS) in cellular networks to serve the far user, who is located at the cell-edge area in such a network. In particular, we show that wireless-powered non-orthogonal multiple access (NOMA) and the cell-center user in such a model can harvest energy from the BS. To overcome disadvantages of the cell-edge user due to its weak received signal, we fabricate a far NOMA user with multiple antennas to achieve performance improvement. In addition, the first scenario only considers a relay link deployed to forward signals to a far NOMA user, while both direct links and relay links are generally enabled to serve a far user in the second scenario. These situations, together with their outage performance, are analyzed and compared to provide insights in the design of a real-multiple-antenna NOMA network, in which the BS is also required to equip multiple antennas for robust quality of transmission. Higher complexity in computations is already known in consideration of outage metrics with respect to performance analysis, since the system model employs multiple antennas. To this end, we employ a transmit antenna selection (TAS) policy to formulate closed-form expressions of outage probability that satisfies the quality-of-service (QoS) requirements in the NOMA network. Our simulation results reveal that the performance of the considered system will be improved in cases of higher quantity of transmit antennas in dedicated devices. Finally, the proposed design in such a NOMA system cannot only ensure a downlink with higher quality to serve a far NOMA user, but also provide significant system performance improvement compared to a traditional NOMA networks using a single antenna.

In this paper, 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 paper, 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. INDEX TERMSPower domain-based non-orthogonal multiple access, energy harvesting, small-cell, fullduplex, outage probability.