Digital Self-Interference Cancellation Scheme for Full-Duplex Cellular System in 5G

Full-duplex cellular (FDC) system, which introduces in-band full-duplex (IBFD) to the cellular system, has been paid attention to for increasing spectral efficiency in 5G and 6G systems. IBFD causes new interferences, such as self-interference (SI), because uplink (UL) and downlink (DL) communications are performed simultaneously on the same frequency resources; however, if the new interferences problem can be overcome, IBFD can ideally improve spectral efficiency up to twice that of half-duplex (HD) system. Many SI cancellations have been proposed; however, to the best of our knowledge, there has been no study of digital SI cancellation for application of IBFD to the 5G system by taking into account the 5G signal configuration and the impact on the performance of low-density parity-check (LDPC) code. In this paper, we propose a digital SI cancellation for applying to the 5G-based orthogonal frequency division multiplexing (OFDM) signal. First, we propose a demodulation reference signal (DMRS) configuration to improve the estimation accuracy of the SI channel. Second, the noise power estimation scheme using the proposed DMRS configuration is also proposed for decoding 5G adopted LDPC. Finally, the proposed scheme is evaluated by computer simulations, and we found that the communication quality in IBFD operation becomes equivalent to that in HD operation by applying the proposed digital SI cancellation.