Exploiting direct link in EH based two-way DF half-duplex relaying network: Outage probability analysis

Relay communication is considered as a popular solution for expanding the coverage, increasing the transmission capacity and reducing the power consumption of the communication networks. In this paper, we proposed and investigated the two-way decode-and-forward (DF) half-duplex (HD) relaying network with the direct link between two sources S1 and S2. Firstly, the system model, energy harvesting (EH) and information transmission (IT) are presented. The closed-form analytical expression of the system outage probability (OP) is analyzed and derived in the next stage. Finally, the correctness of the analytical expressions is verified by Monte Carlo simulation. The research results show that the analytical and simulation are the same in connection with the primary system parameters.

Outage-Based Resource Allocation for DF Two-Way Relay Networks with Energy Harvesting

A joint resource allocation algorithm to minimize the system outage probability is proposed for a decode-and-forward (DF) two-way relay network with simultaneous wireless information and power transfer (SWIPT) under a total power constraint. In this network, the two sources nodes exchange information with the help of a passive relay, which is assumed to help the two source nodes’ communication without consuming its own energy by exploiting an energy-harvesting protocol, the power splitting (PS) protocol. An optimization framework to jointly optimize power allocation (PA) at the source nodes and PS at the relay is developed. Since the formulated joint optimization problem is non-convex, the solution is developed in two steps. First, the conditionally optimal PS ratio at the relay node for a given PA ratio is explored; then, the closed-form of the optimal PA in the sense of minimizing the system outage probability with instantaneous channel state information (CSI) is derived. Analysis shows that the optimal design depends on the channel condition and the rate threshold. Simulation results are obtained to validate the analytical results. Comparison with three existing schemes shows that the proposed optimized scheme has the minimum system outage probability.

Performance Analysis of Cognitive Two-Way Networks with Interference from Primary User over Nakagami-m Fading Channels

A cognitive underlay two-way relay network taking into account interference links from primary transmitter to secondary receivers over Nakagami-m fading channels is analyzed in this article. In this model, a secondary system including two terminal nodes exchanges data through a decode-and-forward (DF) relay node. Under the underlay approach, all secondary transmitter must adjust transmit power to protect the primary communications. We derive the exact and asymptotic closed-form expression for the secondary system outage probability over Nakagami-m fading channels showing the system diversity. Monte-Carlo simulation are performed to verify the analysis results as well as to show the system characteristics

Outage Analysis and Optimization of SWIPT in Network-Coded Two-Way Relay Networks

This paper investigates the outage performance of simultaneous wireless information and power transfer (SWIPT) in network-coded two-way relay systems, where a relay first harvests energy from the signals transmitted by two sources and then uses the harvested energy to forward the received information to the two sources. We consider two transmission protocols, power splitting two-way relay (PS-TWR) and time switching two-way relay (TS-TWR) protocols. We present two explicit expressions for the system outage probability of the two protocols and further derive approximate expressions for them in high and low SNR cases. To explore the system performance limits, two optimization problems are formulated to minimize the system outage probability. Since the problems are nonconvex and have no known solution methods, a genetic algorithm- (GA-) based algorithm is designed. Numerical and simulation results validate our theoretical analysis. It is shown that, by jointly optimizing the time assignment and SWIPT receiver parameters, a great performance gain can be achieved for both PS-TWR and TS-TWR. Moreover, the optimized PS-TWR always outperforms the optimized TS-TWR in terms of outage performance. Additionally, the effects of parameters including relay location and transmit powers are also discussed, which provide some insights for the SWIPT-enabled two-way relay networks.

Outage Analysis of Cooperative Transmission with Energy Harvesting Relay: Time Switching versus Power Splitting

This paper investigates the multiuser transmission network with an energy harvesting (EH) cooperative relay, where a source transmits independent information to multiple destinations with the help of an energy constrained relay. The relay can harvest energy from the radio frequency (RF) signals transmitted from the source, and it helps the multiuser transmission only by consuming the harvested energy. By adopting the time switching and the power splitting relay receiver architectures, we firstly propose two protocols, the time switching cooperative multiuser transmission (TSCMT) protocol and the power splitting cooperative multiuser transmission (PSCMT) protocol, to enable the simultaneous information processing and EH at the relay for the system. To evaluate the system performance, we theoretically analyze the system outage probability for the two proposed protocols and then derive explicit expressions for each of them, respectively. Numerical results are provided to demonstrate the accuracy of our analytical results and reveal that compared with traditional noncooperative scheme our proposed protocols are green solutions to offer reliable communication and lower system outage probability without consuming additional energy. In particular, for the same transmit power at the source, the PSCMT protocol is superior to the TSCMT protocol to obtain lower system outage probability.