Phase Rotation to Avoid Imaginary Interference Leakage in Multi-user MIMO-OFDM/OQAM Systems

Orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) is a powerful substitute for OFDM owing to its higher spectral efficiency and lower spectral sidelobes. However, in OFDM/OQAM systems the receiver must recover a purely real component from a complex signal, as only an orthogonal condition is provided in the real field, resulting in imaginary interference leakage in multiple input multiple output systems. In this paper, a phase rotation method to avoid imaginary interference leakage by confining intrinsic interference to the imaginary component of the signal is proposed. The method is first applied in solving the interference problem on neighboring subcarriers; thereafter, the application scope is expanded to solving interference on multiple subbands in multi-user systems. Simulation results verify the effectiveness of the proposed method, which has the additional benefit of low receiver complexity.