Analog repeaters can be key to actual MMWave deployments

Analog repeaters report Science Tokyo researchers dramatically enhance coverage of millimeter waves (MMWAVE) in mobile networks by overcoming signal clogging. As demonstrated in field experiments on the Ookayama campus, low-cost repeaters offer promising solutions for 5G and 6G networks either wirelessly or over optical fiber. Both configurations enhance the stability of MMWave signals beyond throughput above 1 Gbps, demonstrating the powerful potential for practical deployments in urban and high traffic areas.

Global demand for high-speed, large-capacity mobile communications continues to grow every year, pushing the telecommunications industry into increasingly sophisticated solutions. Of these, the 5G millimeter wave (MMWAVE) frequency promises low latency and unprecedented speeds above 1 Gbps, making it ideal for emerging applications such as augmented reality and autonomous vehicles.

However, MMWAVE frequency faces important deployment challenges that are hindering actual implementation. As high frequency radio signals, they are prone to blockage, especially due to environmental disorders such as buildings, trees, and even the human body. This limitation leaves it cost-effective to provide technically challenging and comprehensive MMWave coverage.

Contrary to this background, a research team led by Professor Sakaguchi of the Faculty of Electrical and Electronics Engineering at the Department of Science and Science in Japan (Tokyo Science) developed and tested practical solutions to extend MMWave coverage using Analog Relay Stations.

Their paper published in IEEE Access shows how low-cost repeaters can effectively deal with key barriers to strategically deployed MMWave deployment.

The team installed a set of multiple analog repeaters within the 5G/6G demonstration field at Science Tokyo’s Ookayama campus, focusing their experiments on a line of sight (NLOS) environment where direct signals from the base stations are not normally reachable. Each repeater set consists of donor units that receive signals and service units that amplify and transmit them to the user, or forward them to other repeaters. The researchers evaluated two main connection schemes. It is a cascade configuration that uses fiber optic links to connect repeaters, and a fully wireless multihop configuration that relies solely on MMWave links.

Testing has revealed that these analog repeaters can effectively expand coverage to areas that are dead spots by enabling stable communication with throughput above 1 Gbps in previously unreachable zones. The cascade method achieved slightly higher average throughput, while the wireless multihop approach showed more consistent performance with fewer signal drops. Still, both configurations successfully achieved coverage for a larger area that would have been impractical to provide only the base station.

“Our results show that proper placement of analog repeaters can overcome the inherent block losses of MMWAVE and support both stable and large-capacity communication,” Sakaguchi emphasizes.

Another important finding is to create an artificial multipath environment that overlaps with coverage areas of multiple repeaters, further increasing signal stability through what researchers call “diversity of distributed relays.”

“Even if a signal is blocked by a human body simulating blockage, receiving it from multiple repeaters can help maintain signal strength and throughput,” explains Sakaguchi.

Thus, the proposed approach has been proven to be particularly suitable for densely populated, densely populated areas with frequent pedestrian and vehicle movements.

Overall, this innovative solution, as Sakaguchi concludes, portrays a bright future for MMWave in next-generation mobile communications.