6G-Enabling Technology: A New Energy-Efficient mmWave CFmMIMO System for Wireless Communication

Researchers from Korea have developed a new cell-free massive MIMO system that is energy-efficient and outperforms other existing schemes

With 6G mobile communication on the horizon, there is a growing need for cost-effective and environmentally conscious technologies. Recently, mmWave cell-free massive MIMO (CFmMIMO) systems have emerged as promising candidates for 6G technology. A group of researchers from Korea has now developed an energy-efficient mmWave CFmMIMO system for cell-free communication. This system can provide users with immersive and real-time services like cloud games, extended reality (VR, AR, and MR), and remote robotic surgery anywhere.

Mobile communication is expanding rapidly, with 5G already rolled out and 6G under development. To keep up with the growth of mobile traffic, we need new technologies that will help manage traffic, reduce greenhouse gas emissions, and lower power consumption. Cell-free mobile communication removes the dependency on the base stations, contributing to solve the attenuation of signals and signal blockage by obstacles.

Cell-free massive MIMO (CFmMIMO) has recently emerged as an excellent 6G-enabling technology candidate. Based on high macro-diversity gains in addition to channel hardening and favorable propagation inherited from massive MIMO, CFmMIMO offers uniformly high data rates for everyone everywhere, better coverage, and energy efficiency (EE). When combined with mmWave, the resultant technology is a very sustainable option to manage traffic, but research on this has been sparse.

Set against this background, a group of researchers from Korea have proposed a new mmWave CFmMIMO system. This study, led by Dr. Seung-Eun Hong from the Electronics and Telecommunications Research Institute in Korea, was published in the ETRI Journal. “To enable the practical deployment of cell-free communication, we studied an energy-efficient cell-free operation by proposing cooperative beamforming and pilot allocation schemes on the serialized front-haul while reducing CAPEX/OPEX through low-resolution DAC (digital-analog converter) and PS (phase shifter),” says Dr. Hong, explaining the team’s motivation behind the study.

The proposed framework combines a low-complexity radiofrequency (RF) beamforming method, a novel distributed least pilot interference (dLPI) pilot allocation scheme, and a downlink data transmission with low-resolution DACs. The novel dLPI pilot allocation scheme was developed to minimize pilot contamination while maximizing the minimum distance between co-pilot user equipment.

Simulation results showed that even though the proposed method was simple, it outperformed other methods. Furthermore, the team modeled the network power consumption (NPC) of the proposed system and found that the low-resolution PSs and DACs increased EE by minimizing ASE reduction and maximizing NPC saving.

The new architecture is successful in providing consistent and high-quality data services to users anywhere. The team achieved this by distributing lightweight access points around the user and transmitting and receiving the signals as a result of the collaboration of these access points. “By utilizing the proposed technology, we can build a wireless infrastructure with a high capacity and low power consumption without compromising aesthetics through a harmonious arrangement with the existing buildings in hotspot areas such as stadiums and subways. Additionally, this technology can be used to build an advanced 5G/6G private network where we provide stable and high-quality connections in an energy-efficient way for indoor places such as smart factories and airports,” concludes Dr. Hong.

This technology could be seen soon when 6G communication is deployed worldwide.

Reference

Titles of original papers: Energy-Efficient mmWave Cell-Free Massive MIMO Downlink Transmission with Low Resolution DACs and Phase Shifters

DOI: 10.4218/etrij.0000–0000

Name of author: Seung-Eun Hong1, Jee-Hyeon Na1

Affiliation: Electronics and Telecommunications Research Institute, ETRI

About Dr. Seung-Eun Hong

Seung-Eun Hong is a principal researcher of the mobile communication research division at ETRI. He has previously worked on millimeter-wave Wi-Fi standardization and system development and is currently working on 6G and wireless AI. Before coming to ETRI, he developed a mobile WiMAX system at Samsung Electronics. He received his Ph.D. in Engineering from Korea University in 2003 and was a visiting scholar at the University of Colorado Boulder in 2014.