5G • 5G-Advanced (Rel-18)
Analog RF SIC
Analog Domain Self-Interference Cancellation for SBFD
Hardware cancellation circuit at the gNodeB front-end that samples the high-power DL transmit signal and subtracts it before the sensitive UL receiver LNA saturates.
Technical Explanation
In SBFD, the base station transmitter emits +43 dBm while receiving weak uplink signals at -100 dBm, creating up to 140 dB of self-interference. Analog RF SIC taps the transmit path, inverts its phase, adjusts delay and attenuation via tunable RF filter lines, and injects the inverted waveform at the receiver input, achieving 40 to 60 dB of analog isolation before the ADC.
Key Functions
- Prevents high-power transmit leakage from saturating sensitive Low Noise Amplifiers (LNAs)
- Cancels 40 to 60 dB of self-interference directly in the analog radio frequency domain
- Employs multi-tap delay lines and variable attenuators tracking instantaneous antenna reflections
- Protects base station Analog-to-Digital Converters (ADCs) from dynamic range exhaustion
Specifications
3GPP TR 38.858 (Rel-18)
Interfaces
gNodeB RF Front-End
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