PROPAGATION ENVIRONMENT REPRODUCTION DEVICE, PROPAGATION ENVIRONMENT REPRODUCTION METHOD, AND PROPAGATION ENVIRONMENT REPRODUCTION SYSTEM

1 . A propagation environment reproduction device comprising:

a reconfigurable intelligent surface (RIS) that is installed in a propagation environment reproduction space for reproducing a propagation environment of an electromagnetic wave;

a RIS controller that provides a control signal to the RIS;

a transmission antenna that is installed in the propagation environment reproduction space;

a channel emulator that controls a characteristic of an electromagnetic wave transmitted from the transmission antenna;

a reception antenna that is installed in the propagation environment reproduction space as an evaluation target; and

a control server that controls the RIS controller and the channel emulator,

wherein the RIS includes a first RIS that has a characteristic of changing transmittance of the electromagnetic wave according to the control signal and is disposed between the transmission antenna and the reception antenna.

2 . The propagation environment reproduction device according to claim 1 , wherein the RIS includes a sphere RIS configured by disposing the first RIS in a spherical shape so as to surround the reception antenna.

3 . The propagation environment reproduction device according to claim 1 , wherein the RIS includes a second RIS that has a characteristic of changing a reflection direction of the electromagnetic wave according to the control signal and is disposed at least one of on a wall surface, on a ceiling, or on a floor surface, or in the air of the propagation environment reproduction space.

4 . The propagation environment reproduction device according to claim 1 :

wherein the RIS includes:

a second RIS that has a characteristic of changing a reflection direction of the electromagnetic wave according to the control signal and is disposed at least one of on a wall surface, on a ceiling, or on a floor surface, or in the air of the propagation environment reproduction space, and

a third RIS that has a characteristic of changing transmittance of the electromagnetic wave according to the control signal, the first RIS being a surface layer RIS disposed so as to overlap a surface of the second RIS.

5 . The propagation environment reproduction device according to claim 1 , wherein

the propagation environment reproduction space is configured according to a specification indicated by a parameter which is set to reproduce a desired characteristic which is a propagation characteristic caused at a measurement position in a real space,

the RIS and the transmission antenna are disposed according to the specification indicated by the parameter, and

the control server is configured to execute:

controlling the RIS controller such that the first RIS has transmittance indicated by the parameter; and

controlling the channel emulator such that the transmission antenna transmits the electromagnetic wave with a characteristic indicated by the parameter.

6 . A propagation environment reproduction method for reproducing a desired propagation environment at a position of a reception antenna that is installed in a propagation environment reproduction space for reproducing a propagation environment of an electromagnetic wave by using a RIS that is installed in the propagation environment reproduction space and a transmission antenna that is installed in the propagation environment reproduction space, the RIS including a first RIS that has a characteristic of changing transmittance of the electromagnetic wave according to the control signal and is disposed between the transmission antenna and the reception antenna, the propagation environment reproduction method including:

calculating, while changing parameters related to the propagation environment reproduction space, the RIS, and the transmission antenna, a propagation characteristic caused in the propagation environment reproduction space under each of said parameters by a simulation;

creating a learning model that derives, when a propagation characteristic to be reproduced is provided, a parameter causing said propagation characteristic in the propagation environment reproduction space, the learning model being obtained by providing to a propagation environment model as training data a combination of an actual characteristic that is a propagation characteristic actually measured at a measurement position in a real space and a reproduction parameter that is a parameter calculated to cause a propagation characteristic which is same as the actual characteristic in the propagation environment reproduction space;

causing the learning model to derive a parameter for causing a desired propagation characteristic by providing the desired propagation characteristic to the learning model;

configuring the propagation environment reproduction space according to a specification indicated by the parameter derived by the learning model;

disposing the RIS and the transmission antenna in the propagation environment reproduction space according to the specification indicated by the parameter derived by the learning model;

controlling the first RIS such that the first RIS has transmittance indicated by the parameter derived by the learning model; and

controlling a transmission signal from the transmission antenna such that the transmission antenna transmits an electromagnetic wave with a characteristic indicated by the parameter derived by the learning model.

7 . The propagation environment reproduction method according to claim 6 , wherein the RIS includes a sphere RIS configured by disposing the first RIS in a spherical shape so as to surround the reception antenna.

8 . A propagation environment reproduction system comprising:

a RIS that is installed in a propagation environment reproduction space for reproducing a propagation environment of an electromagnetic wave;

a transmission antenna that is installed in the propagation environment reproduction space; and

a reception antenna that is installed in the propagation environment reproduction space as an evaluation target,

wherein the RIS includes a first RIS that has a characteristic of changing transmittance of the electromagnetic wave according to the control signal and is disposed between the transmission antenna and the reception antenna,

the propagation environment reproduction space is configured according to a specification indicated by a parameter which is set to reproduce a desired characteristic which is a propagation characteristic caused at a measurement position in a real space,

the RIS and the transmission antenna are disposed according to the specification indicated by the parameter, and

the propagation environment reproduction system is configured to execute:

controlling the first RIS such that the first RIS has transmittance indicated by the parameter; and

controlling a transmission signal from the transmission antenna such that the transmission antenna transmits an electromagnetic wave with a characteristic indicated by the parameter.

9 . The propagation environment reproduction device according to claim 2 , wherein the RIS includes a second RIS that has a characteristic of changing a reflection direction of the electromagnetic wave according to the control signal and is disposed at least one of on a wall surface, on a ceiling, or on a floor surface, or in the air of the propagation environment reproduction space.