Adaptive SI Cancellation using Measured Impulse Responses for STAR Radio

Simultaneous transmit and receive (STAR) wireless allows for doubling of data capacity and spectral efficiency. This paper proposes an early stage digital self-interference cancellation (SIC) approach for wideband STAR wireless systems. The approach is comprised of two stages: 1) Measurement stage, where the unit impulse response of the residual coupling from transmitter to receiver is measured directly using a digital signal processing (DSP) architecture; 2) Communication stage, where the measured unit impulse response is convolved with the output waveform from the transmitter to subtract the SI in DSP. At the measurement stage, the impulse response of a channel is captured into memory. Subsequently at the communication phase, SI cancellation is applied using the stored values as coefficients in the FIR filter serving as the SI canceller. The in-band STAR impulse response measurement setup employs a 2.4 GHz transceiver and an AMD Xilinx RFSoC ZCU-111 for DSP operations. The verification of this SI approach is provided across a 250 MHz band demonstrating its practical viability in real world STAR wireless applications. This research addresses crucial challenges relative to spectrum congestion and higher data rates in modern wireless communication systems using full duplex STAR techniques.