Ray tracing channel modeling method for reconfigurable intelligent surface wireless communication
Disclosed in the present disclosure is a ray tracing channel modeling method for reconfigurable intelligent surface wireless communication. The method comprises: setting an application scene; implementing RIS deployment and adjustment mode; analyzing a received power distribution of a non-line-of-sight scene; analyzing an angle power spectral density; and specifically analyzing the change of a channel capacity with the change of a transmitting power, a RIS unit number and a RIS deployment position. In the present disclosure, a RIS channel deterministic model based on ray tracing can be used for a static ray tracing simulation software, the deployment of any scale of a reconfigurable intelligent surface at any position in a scene is supported, the ray tracing modeling method of the reconfigurable intelligent surface is enriched, and the channel characteristic analysis of the simulation result has guiding significance for the application and deployment of RIS in indoor scenes.
1 . A ray tracing channel modeling method for reconfigurable intelligent surface wireless communication, wherein the method comprises following steps:
Step S 1 , determining an environmental layout and materials that are applied in the environment, and drawing a simulation environment in a ray tracing software;
Step S 2 , determining antenna parameters, a transceiver layout, and signal waveform parameters, and determining, according to a frequency of a signal center, material parameters, to complete simulation settings;
Step S 3 , determining sizes of units, a number of the units, deployment positions, and a preset control direction of a reconfigurable intelligent surface, wherein the preset control direction is specifically a connecting line direction between a center position of a reconfigurable intelligent surface panel and an antenna at the receiving terminal;
Step S 4 , calculating, according to the adjustment direction, adjustment angles of an azimuth angle and adjustment angles of an elevation angle for each reconfigurable intelligent surface unit, to complete adjustments;
Step S 5 , determining a used algorithm, a highest number of reflections, and types of output results in a ray tracing simulation;
Step S 6 , implementing the ray tracing simulation, and analyzing, according to output data, channel characteristics;
wherein Step 4 specifically includes following steps:
Step S 401 , representing a position of the each reconfigurable intelligent surface unit with a center point of the reconfigurable intelligent surface unit, denoting a coordinate of a reconfigurable intelligent surface unit in an m-th row and a n-th column as C m,n (c x , c y , c z ), a coordinate of the transmitting terminal as T x (t x , t y , t z ), and a coordinate of the receiving terminal as R x (r x , r y , r z ), and calculating an angular bisector between a connecting line T x C m,n and a connecting line C m,n R x ;
Step S 402 , arbitrarily taking a point D on a positive half axis of the angular bisector , making a straight line parallel to a Z-axis through the point D, and enabling, by taking a point E on the vertical line, a Y-axis of the point E equal to c z ;
Step S 403 , arbitrarily taking, along a direction of a positive half axis on the Y-axis through the point C m,n , the point D, and arbitrarily taking, along a negative direction of the Z-axis, a point G;
Step S 404 , calculating, according to a cosine theorem, an azimuth angle θ m,n , that is, ∠EC m,n F, and an elevation angle φ m,n , that is, ∠GC m,n D;
Step S 405 , rotating, according to the calculated elevation angle φ m,n , the reconfigurable intelligent surface unit in the m-th row and the n-th column around the Y-axis, wherein a rotation angle is 90−φ m,n in a case where φ m,n <90°, and the rotation angle is φ m,n −90 in a case where φ m,n >90°, and
Step S 406 , rotating, according to the calculated elevation angle φ m,n , the reconfigurable intelligent surface unit in the m-th row and the n-th column around the Z-axis, wherein a rotation angle is 90−φ m,n in a case where φ m,n <90°, and the rotation angle is φ m,n −90 in a case where φ m,n >90°;
wherein Step S 5 specifically includes following steps:
Step S 501 , setting a simulation area and a noise power spectral density;
Step S 502 , setting the highest number of the reflections in the ray tracing simulation, without considering transmission and diffraction mechanisms;
Step S 503 , setting a routing interval of the transmitting terminal ray and a maximum number of multipaths received by the receiving terminal; and
Step S 504 , setting a type of simulation results that is required to be output, including multipath information, a horizontal arrival angle, and an elevation arrival angle;
wherein Step S 6 specifically includes following steps:
Step S 601 , calculating, according to the multipath information obtained from the simulation, a received power at each receiving terminal, wherein the multipath information obtained from the simulation is h i =P i e jψi , where P i is a received power in an i-th multipath, ψ i is a phase in the i-th multipath, then the received power at the receiving terminal is a sum of the received power in all of the multipaths, and an expression is:
P
r
=
∑
i
=
1
N
p
P
i
,
where P r is the received power at the receiving terminal, and N p is a total number of the multipaths;
Step S 602 , analyzing, according to the calculated received power, the set noise power spectral density and the signal bandwidth, a channel capacity, wherein a calculation expression of the channel capacity is:
SNR
(
dB
)
=
10
log
10
(
P
R
)
-
10
log
10
(
N
total
)
Capacity
=
B
log
2
(
1
+
SNR
)
,
where SNR is a signal-to-noise ratio, P R is the received power of the receiving terminal, N total is a total noise, B is the signal bandwidth, and Capacity is the channel capacity; and
Step S 603 , obtaining, according to the received power and an arrival angle of each path in the multipath information, an angle power spectral density.
2 . The ray tracing channel modeling method for the reconfigurable intelligent surface wireless communication, according to claim 1 , wherein Step S 2 specifically includes following steps:
Step S 201 , in an application scene determined in Step S 1 , determining an antenna type, an antenna polarization type, an antenna aperture, and antenna standing wave ratio; positions of the transmitting terminal and the receiving terminal, point layouts of the transmitting terminal and the receiving terminal, an antenna type matching the transmitting terminal with the receiving terminal, and a receiving threshold of the receiving terminal; and a signal type, a center frequency, and a signal bandwidth; and
Step S 202 , determining, according to the central frequency of the simulation, a dielectric constant of the materials, to complete the simulation settings.