On the Outage Performance of SWIPT-Based Three-Step Two-Way DF Relay Networks

Abstract

In this paper, we study the outage performance of simultaneous wireless information and power transfer (SWIPT) based three-step two-way decode-and-forward (DF) relay networks, where both power-splitting (PS) and "harvest-thenforward" are employed. In particular, we derive the expressions of terminal-to-terminal (T2T) and system outage probabilities based on a Gaussian-Chebyshev quadrature approximation, and obtain the T2T and system outage capacities. The effects of various system parameters, e.g., the static power allocation ratio at the relay, symmetric PS, as well as asymmetric PS, on the outage performance of the investigated network are examined. It is shown that our derived expression for T2T outage capacity is more accurate than existing analytical results, and that the asymmetric PS achieves a higher system outage capacity than the symmetric one when the channels between the relay node and the terminal nodes have different statistic gains.Index Terms-Outage performance, SWIPT based three-step two-way DF relay, power-splitting.

On the Outage Performance of Ambient Backscatter Communications

“…In what follows, we provide two ways to address this problem. One is to use Gaussian-Chebyshev quadrature to obtain an approximation for P b out,k for any given P t , since it can provide sufficient level of accuracy within very few terms [34], [37], [38]. The other is to approximate P b out,k based on a high transmit power of the LT.…”

On the Performance of Battery-Assisted PS-SWIPT Enabled DF Relaying

“…In our considered system, the relay not only runs out of the harvested energy, but also may extract the energy E b (E b ≥ 0) from its battery. Let us focus on the worst case scenario where Rayleigh fading is used to model small-scale fading over each channel [8,[10][11][12][16][17][18][19], and we assume that the small-scale fading follows a complex Gaussian distribution with zero mean and unit variance. Hence, the k-th The relay follows the PS scheme in which each transmission slot is divided into two equal sub-slots.…”

“…Firstly, the derived results can be used to obtain accurate outage and ergodic capacities instead of the computer simulations. Secondly, since the optimal static PS ratio is determined by the statistic channel gains instead of instantaneous channel gains, it is practical to obtain the optimal static ratio offline by using the derived expressions and such an approach has been widely adopted in many works [10][11][12]. Lastly, we can obtain some insights such as how E b affects the optimal PS ratio in terms of energy efficiency, and how to select the assisted energy E b to realize a higher energy efficiency.…”

“…Apart from the traditional EH approach, a new promising solution, i.e., simultaneous wireless information and power transfer (SWIPT), is proposed to harvest energy from an ambient radio-frequency (RF) signal via a power splitting (PS) or time switching (TS) scheme [5]. For the SWIPT based relay system, most existing works were based on the "harvest-then-forward" protocol, i.e., the transmit power of a relay only relies on the harvested energy, and various TS/PS schemes were proposed to improve the outage/ergodic capacity the performance (see [6][7][8][9][10][11][12][13] and reference therein).…”

Energy Efficiency Optimization for AF Relaying with TS-SWIPT

“…However, such assumption does not hold in practice. Motivated by this, two practical receiver protocols, namely, time-switching (TS) and power-splitting (PS), are proposed in [2,3]. For the former one, energy harvesting (EH) and information processing (IP) are switched over time, while, for the later, the received signal at receiver is split into two different power streams for EH and IP by a PS ratio.…”