6G • RAN
Active-RIS
Power-Amplified Active Reconfigurable Surface
Metasurfaces integrating low-power reflection amplifiers to overcome the severe multiplicative path loss inherent in passive double-fading channels.
Technical Explanation
Passive RIS suffer from 'double path loss': the signal decays from the base station to the RIS, and decays again from the RIS to the user. At high frequencies, this multiplicative attenuation severely restricts passive RIS gains. Active-RIS addresses this by integrating low-noise, low-power reflection amplifiers (such as tunnel diodes or negative resistance circuits) into each element, amplifying reflected beams by 10-25 dB to achieve dramatic throughput gains while consuming a fraction of a base station's power.
Key Functions
- Active reflection amplification overcoming multiplicative double-path-loss attenuation
- Low-power operational profile (<20-50W) substantially lower than full base stations
- Significant coverage extension in deep shadow and non-line-of-sight Sub-THz canyons
- Integrated noise filtering preventing amplification of background out-of-band interference
- Hybrid active-passive element configurations balancing power efficiency and beam gain
Specifications
IEEE Wireless Communications Letters, 3GPP Rel-20 Study on Active Surfaces
Interfaces
Active-RIS-CtrlRF-Power-Feed
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