Rate Optimization of Two-Way Relaying with Wireless Information and Power Transfer

Abstract

Abstract:We consider the simultaneous wireless information and power transfer in two-phase decode-and-forward two-way relaying networks, where a relay harvests the energy from the signal to be relayed through either power splitting or time splitting. Here, we formulate the resource allocation problems optimizing the time-phase and signal splitting ratios to maximize the sum rate of the two communicating devices. The joint optimization problems are shown to be convex for both the power splitting and time splitting approaches after some transformation if required to be solvable with an existing solver. To lower the computational complexity, we also present the suboptimal methods optimizing the splitting ratio for the fixed time-phase and derive a closed-form solution for the suboptimal method based on the power splitting. The results demonstrate that the power splitting approaches outperform their time splitting counterparts and the suboptimal power splitting approach provides a performance close to the optimal one while reducing the complexity significantly.

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

“…Substituting Systems (8), (11) and (13) into (7), the approximate expression for P s out can be written as (16), as shown at the top of the next page. Accordingly, the outage capacity is calculated as…”

“…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).…”