Multi-Stream Signal Separation Based on Asynchronous Control Meta-Surface Antenna

The real-time reconfigurable characteristics of meta-surface antennas can be used to separate multi-stream signals under the condition of single radio frequency (RF). However, with the increase of the symbol rate and the number of antenna arrays in the future, it will face the problem that the state switch rate of the electromagnetic unit is not enough to reach the upper limit of array effective degrees of freedom (DOF) of the meta-surface antenna. To solve this problem, a theory of asynchronous control meta-surface antenna is proposed in this paper. By designing the starting time of different element state switching, different electromagnetic element states are staggered to improve the array effective DOF of the meta-surface antenna. Then, an electromagnetic unit state design algorithm of asynchronous control meta-surface antenna based on the minimum condition number of equivalent channel matrix is proposed. We improve the sparrow search algorithm to solve the condition number minimization problem in order to obtain the better multi-stream signal separation performance. The simulation results show that compared with the synchronous control meta-surface antenna, theory proposed in this paper can improve the effective DOF of array under the condition of limited switch rate, and can effectively reduce the receiving bit error rate and improve spectral efficiency when separating multi-stream signals.