SWIPT-Enabled Relaying Networks for Next-Generation Wireless Systems: A Review of Achievable Rates and Future Challenges

Efficiently powering the billions of mobile devices currently in use is a growing challenge, as most of these devices are battery-operated and require substantial energy for reliable signal transmission. To address this, harvesting energy from radio frequency (RF) signals has emerged as a promising solution. This approach, known as Simultaneous Wireless Information and Power Transfer (SWIPT), has garnered increasing attention from both researchers and industry due to its potential to extend battery life. Among its various applications, relaying networks represent a key area in which SWIPT can make a significant impact. These networks offer improved coverage, higher data rates, lower latency, and better energy and spectral efficiency, which are critical attributes for meeting the demands of next-generation (5G/6G) ultra-dense wireless networks. In this paper, we provide a comprehensive review of SWIPT in relaying networks, exploring its principles, structures, protocols, and technical aspects. We also examine the achievable rates in SWIPT-enabled relaying networks and discuss how machine learning could enhance these systems, presenting it as a promising direction for future research. Finally, we highlight several key challenges that remain to be addressed, emphasizing the need for continued exploration in the rapidly evolving landscape of wireless technology.