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Recently, non-orthogonal multiple access (NOMA) and energy harvesting (EH) from radio frequency (RF) have been considered as promising candidates for next-generation mobile communications. In this paper, we investigate a novel solution to enhance the reliability and the supply stability of a downlink NOMA relaying networks, in which we integrate two techniques: (i) simultaneous wireless information and power transfer, i.e. the relay node can harvest the energy from source signals and use this energy to help forward information from source node to two user nodes; and (ii) data buffer aid at relay node, i.e. the data packets received from the source can be stored in a buffer and then be re-transmitted to the destination nodes only when the channel condition is good. The performance of the proposed system is analyzed rigorously to derive the system outage probability (OP), throughput and the average packet delay. Furthermore, a power allocation optimization problem to minimize the OP is formulated and solution to this problem is also provided. In addition, the optimal transmission rates to maximize the throughput of each user are presented in numerical results. Monte Carlo simulations are conducted to verify the analytical results, which confirms that with data buffer at relay, the overall outage probability (OOP) can be reduced significantly. [ABSTRACT FROM AUTHOR]

In this paper, we propose a full-duplex (FD) relaying system with multi-input multi-output (MIMO) with simultaneous wireless information and power transfer (SWIPT), where the communication from source to destination is assisted by a full-duplex decode-and-forward (DF) relay. The time switching (TS) protocol is used at the relay to harvest the energy of radio-frequency (RF) signals transmitted from the source. To improve both system performance and the amount of harvested energy, multiple antennas are used at source and destination. Transmit antenna selection (TAS) is employed at the source with an assumption that the feedback of channel state information (CSI) is outdated. Meanwhile, both selection combining (SC) and maximal ratio combining (MRC) techniques are applied at the destination. The closed-form expressions of the outage probability (OP), optimal throughput, and symbol error probability (SEP) are derived subject to the outdated CSI over Rayleigh fading channels. We also make a comparison between the performance of the proposed MIMO-FD relaying system with SWIPT and that of MIMO half-duplex (HD) relaying systems with and without SWIPT. The validity of derived mathematical expressions is verified by Monte-Carlo simulations. Numerical results show that the TAS/MRC scheme gives better system performance than the TAS/SC scheme. Moreover, higher energy harvesting time is needed to maximize the throughput than to minimize the OP. [ABSTRACT FROM AUTHOR]

The study of the effects of Nakagami- $m$ fading channels with both integer and non-integer $m$ plays an important role in the design of practical wireless systems. In this paper, we investigate a dual-hop cooperative communication system, where source node communicates with destination node through direct and relaying paths. Partial relay selection (PRS) scheme is used to select the best relay among $N$ relays which are capable of harvesting energy from radio frequency (RF) signals. At the destination, selection combining (SC) technique is employed to combine the signals of the direct path and the relaying path. We consider two relaying protocols, i.e. amplify-and-forward (AF) and decode-and-forward (DF). For both AF and DF protocols, we derive the tight lower-bound closed-form approximate expression and the exact closed-form expression of the outage probability (OP) over Nakagami- $m$ fading channels with both integer and non-integer $m$. Moreover, the optimal energy harvesting duration which minimizes the OP is also determined. Numerical results show that, the OP of DF protocol and its minimum value is lower than those of AF protocol for the same parameter settings. Moreover, the time switching ratio which gives the smallest OP in the case without direct path is larger than the case with direct path. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a dual hop communication decode-and-forward scheme relay system where a source node wants to transmit simultaneously two symbols to two desired destinations with the help of one selected energy constraint relay node. The power for operation of relay is come from the ambient radio frequency energy harvesting and the non-orthogonal multiple access technology is applied. We mathematically evaluate the impact of partial relay selection on the system performance by considering the undecodable probability of symbol for which symbols can not be decoded at the relay node or two destinations. Furthermore, the undecodable probability and the ergodic capacity are analyzed under the effect of imperfect and perfect successive interference cancellation (SIC). The results of theoretical analysis is similar to the simulation results, especially in the high region of transmit power. It verifies the correctness of mathmatical closed-form in our analysis. The results also show that the performance of the system are significantly influenced by the efficiency of SIC technology and the number of relay nodes. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we analyze the performance of the full-duplex relay system, wherein two terminal nodes operate in the half-duplex mode and the relay node with decode-and-forward scheme operates in the full-duplex mode. We consider the replenishes energy from radio frequency (RF) for the source and the relay nodes through the power beacon (PB) combine with the case of imperfect self-interference cancellation (SIC) at the full-duplex relay. To increase the collected energy for the source and the relay, on the other hand decreasing the complexity for the high power amplifier at the PB, we assume that the PB has multiple antennas. Using theoretical analysis, we obtain the closed-form of the exact outage probability of the system over Nakagami- m fading channels. Furthermore, the exact expression for the symbol error probability of the system is derived to evaluate the system performance with different modulation schemes. Based on this analysis, the impact of the antenna numbers, m parameters, the time duration for harvesting and the residual self-interference are considered. The Monte-Carlo simulations are used to demonstrate the correctness of numerical results. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we propose and analyze a downlink non-orthogonal multiple access (NOMA) relay system with full-duplex transmission model and decode-and-forward (DF) scheme. We assume that the source and the destination nodes have fixed power, whereas relay nodes have constrained energies and should harvest radio frequency (RF) energy from the source for operation power. The outage performance of this system is analyzed over the Nakagami- m fading channel, full-duplex transmission protocol and imperfect channel state information (CSI), and then the duration of energy harvesting in every block time, α T , is optimized to achieve the maximal throughput. Furthermore, the closed-form of outage probabilities and the fraction α are derived and evaluated in several scenarios. Moreover, the optimal power allocation coefficients that achieve the minimal outage probability while keeping the fairness in outage performance of end users are discussed. The analytical results are verified by Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

In this paper, we propose a non-orthogonal multiple access (NOMA) relaying system, where a source node communicates simultaneously with multiple users via the assistance of the best amplify-and-forward (AF) relay. The best relay is selected among N relays which are capable of harvesting the energy from radio frequency (RF) signals. We analyze the performance of the proposed NOMA relaying system in the conditions of imperfect channel state information (CSI) and Rayleigh fading by deriving the exact expressions of the outage probability (OP) and the approximate expression of the ergodic capacities of each user and the whole system. We also determine the optimal energy harvesting duration which minimizes the OP. Numerical results show that, for the same parameter settings, the performance of the proposed NOMA relaying system, especially the ergodic capacity of the whole system, outperforms that of the orthogonal-multiple-access (OMA) relaying system. Monte-Carlo simulations are used to validate the correctness of the analytical results. [ABSTRACT FROM AUTHOR]