Digitally-assisted analog self-interference cancellation for STAR system

To enable simultaneous transmit and receive (STAR) on the same frequency in a densely deployed space with multi-interference sources, this work proposes a digitally-assisted analog self-interference cancellation method, which can acquire reference signals through flexible wired/wire-less switching access. Based on this method, the Minimum Mean Square Error algorithm with known channel state information is derived in detail, determining the upper limit of the cancellation performance, and the Adaptive Dithered Linear Search algorithm for real-time engineering cancellation is given. The correctness of theoretical analysis is verified by the practical self-interference channel measured by a vector network analyzer. Furthermore, we have designed and implemented the corresponding multi-interference cancellation prototype with the digitally-assisted structure, capable of handling multiple interferences (up to three) and supporting a large receive bandwidth of 100 MHz as well as a wide frequency coverage from 30 MHz to 3000 MHz. Prototype test results demonstrate that in the presence of three interferences, when the single interference bandwidth is 0.2/2/20 MHz (corresponding to the receive bandwidth of 2/20/100 MHz), the cancellation performance can reach 46/32/22 dB or more.