Two-Dimensional Quasi-Complementary Array Sets for Omnidirectional Transmission in Massive MIMO Systems

Golay complementary array sets (GCASs) have excellent practical applications for omnidirectional precoding in massive multi-input and multi-output (MIMO) systems due to their ideal autocorrelation property. However, the array parameters of the GCAS are limited in the literature, which means it cannot accommodate more antenna configurations in many scenes. In this letter, a class of two-dimensional (2-D) quasi-complementary array sets (QCASs) is introduced, in which the peak sidelobe level (PSL) of the sum aperiodic autocorrelations holds below a certain threshold. Furthermore, based on Newton's method, a numerical optimization algorithm for generating QCASs is presented. It is noted that 2-D QCASs are available in more flexible array sizes than the conventional 2-D GCASs and hence these arrays are useful in more MIMO systems. Finally, simulation results of the omnidirectional precoding based on the proposed 2-D QCASs are provided to verify the transmission performance.