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

Claim 0:
1. An OAM (Orbital Angular Momentum) mode multiplexing transmission apparatus, comprising:
at least a processor; and
a memory in circuit communication with the processor,
wherein the processor is configured to execute program instructions stored in the memory to implement:
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 that corrects an antenna tilt and an individual difference in characteristics among RF (Radio Frequency) circuits by using correction values;
a correction value calculation circuit that calculates the correction values; and
a correction value feedback part that regularly feeds back the correction values from a receiving end to a transmitting end;
wherein 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; and
wherein the correction value calculation circuit regularly calculates 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.