Space division full-duplex scheme with joint scheduling and precoding design

In-band full-duplex, allowing simultaneous transmission and reception on the same device over the same frequency, can double the spectral efficiency theoretically. However, the severe self-interference challenges the physical layer design. Thus, to simplify the interference cancellation (IC), the space division full-duplex (SDFD) is considered, where two spatial-separated transmission points (TPs), e.g., base stations, simultaneously serve the same cell in downlink (DL) and uplink (UL), respectively. In this paper, assuming the TP has digital-domain IC capability only, we study the SDFD scheme in heterogeneous network, i.e., a small cell (named SDFD-cell) is served as SDFD via macro TP (MTP) in DL and small TP (STP) in UL. Due to the inter-TP interference, the capacity of SDFD-cell is restricted by the digital-domain IC. Moreover, SDFD degrades the performance of other non-SDFD-cells. Therefore, we propose a joint scheduling and precoding design algorithm. The scheduling scheme selects a user equipment (UE) pair in the SDFD-cell for DL and UL transmissions as proportional fairness metric. Then, an optimal precoder is designed for MTP to reduce the interference in both SDFD-cell and non-SDFD-cells. The simulation results verify that the proposed algorithm can significantly improve the capacity of the SDFD-cell with limited capacity degradation in non-SDFD-cells.