## 1 Introduction  
Device-to-device (D2D) communication has become a focal point of research in wireless networks, particularly with its adoption in the 3 GPP LTE-A standard (Release 12). D2D technology allows direct communication between devices within close proximity, enabling efficient spectrum utilization, improved throughput, and reduced load on base stations (BSs). In [1, 2, 3, 4, 5], resource and transmit power optimization schemes were proposed to improve the D2D performance in cellular networks. In [1], the authors introduced joint resource and transmit power optimization methods under the assumption that each cellular user's (CU's) resource can be shared with at most one D2D pair, and vice versa. Similarly, [2] proposed schemes that jointly optimize mode selection, power control, and resource allocation across three modes: cellular, dedicated-channel D2D, and reuse-channel D2D. In [3], decentralized transmit power optimization strategies were developed for networks with randomly deployed devices. The study in [4] aimed to enhance energy efficiency by jointly optimizing resource allocation and transmit power. The authors in [5] proposed power optimization schemes tailored to relay-assisted D2D communications. Moreover, various resource allocation strategies for D2D communications in future heterogeneous networks were proposed in [6]. In the evolving landscape of 5G and beyond, achieving high spectral efficiency while supporting high energy efficiency is critical, especially in energy-constrained environments, such as Internet of Things (IoT) applications, where devices must operate without frequent battery replacements [7]. To address these challenges, the integration of D2D communication with simultaneous wireless information and power transfer (SWIPT) has been explored in several studies [8; 9; 10; 11; 12; 13; 14; 15]. In [8], strategies for optimizing transmit power and resource allocation were proposed, with the assumption that each D2D pair is restricted to reusing only one resource from the CUs. In [9], the authors proposed joint resource and transmit power optimization schemes while accounting for the energy causality constraint. In [10], the authors introduced beamforming design and resource allocation strategies to leverage multiple antennas at the BS effectively. In [11], joint transmit power and subcarrier allocation strategies were proposed for networks using orthogonal frequency-division multiple access (OFDMA). In [12], schemes for power control and resource allocation were suggested to maximize energy efficiency. In [13], an analysis of the outage probability was conducted for cognitive D2D communications. In [14], an analysis was conducted on the ergodic capacity and outage probability for fading channels in networks utilizing non-orthogonal multiple access (NOMA) and full-duplex relaying. Despite the fact that these studies [8; 9; 10; 11; 12; 13; 14] ensure a certain level of performance for the CUs, they consistently show that the performance of CUs considerably declines compared to that of CUs without D2D communication, mainly due to the interference from D2D transmitters (DTs). To overcome these issues, the authors in [15] proposed transmit power optimization schemes for time-switching SWIPT-based D2D communications. However, compared to the time-switching method assumed in [15], the power-splitting approach can achieve a larger energy-rate region [16]. Additionally, [15] did not consider energy signal transmission. With the utilization of energy signal transmission, it is possible to assist energy harvesting at the CU without interfering with its information decoding, which allows for higher transmit power in D2D communications and ultimately improves performance. The absence of energy signal transmission, combined with the use of the time-switching method, may result in significant performance degradation in D2D communications due to the inefficient utilization of transmit power at the DT.