The Industrial Internet of Things (IIoTs) is a technology that utilizes wireless sensors, controllers, and mobile communication technologies to optimize industrial production processes and increase efficiency. Therefore, it is essential to build a robust network for data transmission and power transfer with the ability to support numerous IoT devices.
For this, wireless power transfer is a promising technology that uses radio frequency signals to power small devices that consume minimal power.
Recently, simultaneous wireless information and power transfer (SWIPT)-enabled nonorthogonal multiple access (NOMA) systems have been gaining recognition as a promising technology for enabling the IIoTs. This system is particularly useful because it can extend the lifetime of small, battery-driven sensors and other devices.
However, the energy efficiency of this system significantly decreases with the transmission distance from the central controller.
To overcome this limitation, a team of researchers from Korea Maritime and Ocean University has developed an energy-efficient framework by applying SWIPT-NOMA to a distributed antenna system (DAS) to improve the spectral efficiency and energy efficiency of the IIoTs. The new technology has the potential to pave the way for more efficient and optimized IoT environments.
“By applying a DAS with supporting antennas relatively close to edge users alongside a central base station, SWIPT-NOMA’s loss with growing distance can be reduced efficiently. This improves information decoding and energy harvesting performance,” explains Professor Dong-Wook Seo, who led the research.
The proposed SWIPT-NOMA-DAS system was optimized using a three-step iterative algorithm devised by the researchers to maximize energy efficiency.
Firstly, researchers focused on optimizing the power allocation for the central IoT controller. Then, they worked on optimizing the power allocation for NOMA signaling and power splitting (PS) assignment for SWIPT jointly while minimizing the data rates and harvested energy requirements.
Finally, the team analyzed an outage event where the system cannot provide sufficient energy and data rates, extending the joint power allocation and PS assignment optimization method to the multi-cluster scenario.
To verify the effectiveness of the proposed method, the team validated their algorithm through extensive numerical simulations. The results showed that the proposed SWIPT-NOMA-DAS system provides energy efficiency of more than five times that of SWIPT-NOMA without DAS. Additionally, it exhibited more than 10% improvement in performance over SWIPT-OMA-DAS.
“This technology ensures very efficient energy consumption and offers various advantages such as convenience, low power, and battery life extension,” Dr. Seo said in the press release, highlighting the significance of their study. “Thus, it can be applied to smartphones, laptops, wearable devices, and electric vehicles. Most importantly, the SWIPT-NOMA-DAS system can optimize resource allocation and efficiently perform wireless charging and information transmission for users in an IoT environment.”
Journal reference:
- Dongjae Kim, Minseok Choi, and Dong-Wook Seo. Energy-Efficient Power Control for Simultaneous Wireless Information and Power Transfer – Nonorthogonal Multiple Access in Distributed Antenna Systems. IEEE Transactions on Industrial Informatics, 2023; DOI: 10.1109/TII.2022.3217503