Unlocking faster multiplexing for 6G low-earth orbit satellites

A novel time-division MIMO technology enables phased-array receivers to operate faster with exceptional area efficiency and low power, as reported by researchers from the Institute of Science Tokyo. The proposed system significantly reduces circuit complexity for 5G and 6G networks, including non-terrestrial nodes, by reusing signal paths through fast switching. It demonstrated a record-setting 38.4 Gbps data rate across eight streams in a 65 nm CMOS integrated circuit.

The next generation of wireless communications technology, 6G, promises ultra-high data rates and wide coverage that will transform how we connect globally. Central to this vision are non-terrestrial networks using low Earth orbit (LEO) satellites, which will enable seamless integration between terrestrial and satellite networks. To realize this ambitious goal, advanced phased-array antennas capable of multi-beam operation are essential, as they allow the simultaneous transmission and reception of multiple radio beams across various directions and ranges.

Multiple-Input Multiple-Output (MIMO) technology is also crucial for addressing the increasing data throughput demands of future 6G networks. MIMO increases a network’s capacity through multiplexing, which involves sharing the same radio channel for multiple signal streams.

However, conventional MIMO systems face a significant challenge: circuit complexity grows proportionally to the product of the number of antennas and MIMO streams, making the integration of large-scale MIMO systems extremely difficult. This issue becomes even more pressing in satellites, where weight, size, and power consumption constraints are paramount, limiting the practical deployment of traditional MIMO architectures.

To address these limitations, a research team led by Professor Kenichi Okada from the Department of Electrical and Electronic Engineering at Institute of Science Tokyo (Science Tokyo), Japan, has developed a groundbreaking solution. Their work, presented at the 2025 IEEE Symposium on VLSI Technology and Circuits held from June 8–12, 2025, introduces a novel time-division MIMO technology that enables phased-array receivers to operate much faster than conventional systems while maintaining exceptional area efficiency and low power consumption.

The key innovation lies in the team’s proprietary non-uniform time-hopping approach, which achieves high-speed beam switching within the phased-array antenna module without the need to scale the circuit according to the number of MIMO streams. Unlike traditional systems that rely on spatial multiplexing, this design reuses the signal paths for different streams through fast, random switching, significantly reducing chip area requirements.

The researchers implemented a receiver in an integrated circuit using a 65 nm silicon CMOS process, incorporating high-speed switching phase shifters to enhance the device’s resistance to interference. The system integrates eight signal paths with synchronized switches and operates at an impressive clock frequency of 3.2 GHz.

Through over-the-air measurements, the team demonstrated remarkable performance capabilities. The receiver successfully achieved 4×4 MIMO signal reception for both horizontal and vertical polarizations, delivering a maximum data rate of 38.4 Gbps across eight streams.

“Among recently reported millimeter-wave phased-array MIMO receivers, this device demonstrates the highest bit rate with the best area efficiency achieved to date,” explains Okada.

Overall, this technology represents a crucial advancement for 6G. By enabling multi-beam capability in LEO satellites while maintaining compact circuit size and low power consumption, the innovations presented in this study pave the way for practical large-scale MIMO systems that can support the demands of next-generation wireless networks.

“The developed receiver can be integrated into the Internet of Things and mobile devices for both 5G and 6G, as well as LEO satellites. It is a major step forward toward the commercialization and application of new communication services that leverage high bit rates, including non-terrestrial networks,” remarks Okada.

Further efforts in this field will hopefully help us realize the vision of a fully connected Earth, leveraging terrestrial and satellite networks in ways thought impossible only a few years ago.