Patent ID: 11936447
Assignee: NEC CORPORATION
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 8:
9. A method for correcting an OAM (Orbital Angular Momentum) mode multiplexing transmission apparatus, which includes a UCA (Uniform Circular Array) antenna that includes N antenna elements (N is an integer of 2 or more) arranged in a ring shape at equal intervals, a correction circuit, a correction value calculation circuit that calculates correction values, and a correction value feedback part and in which the correction value calculation circuit is connected to a database that stores information about an ideal MIMO (Multiple Input and Multiple Output) channel matrix, which is calculated by using an array diameter of the UCA antenna, a number of antenna elements, an RF frequency, and a link distance as parameters, in a state in which transmission and reception UCA antennas face each other, or is connected to a calculation apparatus that calculates the information, the method comprising:
by the correction value calculation circuit, regularly calculating the correction values relating to signal phase rotation by using a MIMO channel matrix estimated with known signals embedded in received transmission frames and the ideal MIMO channel matrix;
by the correction circuit, correcting an antenna tilt and an individual difference in characteristics among RF circuits by using the correction values; and
by the correction value feedback part, regularly feeding back the correction values from a receiving end to a transmitting end.