Hybrid Interference Mitigation Using Analog Prewhitening

Abstract

Strong interferences occur in several wireless scenarios, such as full-duplex wireless communications and heterogenous networks in unlicensed spectrum. Because strong interferences can cause excessive quantization noise in the receiver’s analog-to-digital converters (ADC), mitigation of strong interferences needs to be conducted not only after but before the ADCs, i.e., via hybrid processing – an actively researched topic in recent years. In this paper, we propose to use an M-input M-output analog phase shifter network (PSN) between the receiving antennas and the ADCs to prewhiten spatially the interferences (plus signal and noise). This scheme, referred to as the Hybrid Interference Mitigation using Analog Prewhitening (HIMAP), requires no information about the interferences except an estimated spatial covariance matrix. Before the ADCs, the HIMAP scheme suppresses the strong interferences through optimizing the PSN; after the ADCs, the HIMAP suppresses the residual interferences through employing minimum mean squared error (MMSE) beamforming. The simulation results verify the effectiveness of the HIMAP scheme.