JP3092650B2 - Electric field strength calculator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for calculating the electric field strength in a service area in mobile communication. In particular, the present invention, the ray radiated from the wave source is reflected by the structure,
The present invention relates to an electric field intensity calculation device that calculates an electric field intensity when a transmission or diffraction arrives at a receiving point.

[0002]

2. Description of the Related Art There is a ray tracing method as a method for calculating the electric field strength in a service area in mobile communication. As shown in FIG. 1, in the ray tracing method, a wave source BS which is a transmission point is used.
An elementary wave (ray) of a radio wave radiated from is repeatedly reflected, transmitted, or diffracted by structures 40, 42, and 44 such as walls and columns, and tracks a locus that reaches the reception point P. The electric field strength is calculated by adding the power of all the rays that have reached the receiving point. There are two methods for obtaining the trajectory of the ray from the transmission point BS to the reception point P. One is the image method (image me
thod) and the other is a launching meth
od).

FIG. 2 shows a calculation method based on the image method. In the image method, a reflection point and a transmission point between the transmission point BS and the reception point P are geometrically obtained. According to the image method, a ray reaching the receiving point P can be calculated accurately. However, in order to determine the reflection surface and the diffraction point between the transmission point and the reception point, it is necessary to search for the ray that reaches the reception point from all combinations of the reflection surface and the diffraction point of all structures. . For this reason, there is a disadvantage that the amount of calculation increases exponentially when the number of reflection surfaces and diffraction points of the structure increases. This point is described in detail in, for example, Ken Takahashi et al .: "Simulation of radio wave propagation using image method", IEICE Technical Report, RCS94-125 (1994-11).

[0004]

FIG. 3 shows a calculation method based on the launching method. In the routing method, the transmission point B
Launch a ray discretely from the S at a constant angle Δθ (launchin
g), the trajectory is sequentially tracked, and the electric field strength of the ray reaching the reception point P is calculated. In this method, since it is not necessary to obtain the combination of the reflection surfaces and diffraction points of all the structures unlike the image method, the amount of calculation can be reduced. However, since rays are fired at discrete angles, the probability of finding a ray that completely matches the receiving point P is small as shown in FIG.

On the other hand, as shown in FIG. 5, a fixed reception area ΔS is defined around a reception point P, and the reception area ΔS is defined.
A ray that reaches S may be regarded as a ray that has reached the receiving point P. However, in this method, depending on the distance to the receiving point and the magnitude of the angles Δθ and ΔS at which the rays are fired,
The number of rays reaching the reception area ΔS is different. FIG. 6A shows an example in which one ray reaches the reception area ΔS, and FIG. 6B shows an example in which two rays reach the reception area ΔS. As described above, since the number of rays that reach the reception area ΔS may be different from the number of rays that should originally reach, the electric field strength cannot be calculated accurately.

Further, as shown in FIG. 7, when Δθ is small, rays of the same route arrive at the receiving area ΔS in an overlapping manner. For this reason, the electric field strength obtained by adding the rays becomes higher than the actual one. If the receiving area ΔS is reduced to eliminate the overlapping of rays, the rays that should originally arrive will not arrive, so the electric field strength obtained by adding the rays is calculated lower than the actual one. Theoretically, a method of appropriately changing the reception area ΔS for each calculation is conceivable, but an appropriate calculation method of the reception area has not been established yet.

Accordingly, an object of the present invention is to provide an electric field intensity calculation apparatus which can avoid the redundant addition of rays even when Δθ is set small in a launching method capable of high-speed processing. And

[0008]

In order to achieve the above object, in the electric field intensity calculation apparatus according to the present invention, each ray emitted from the wave source of the radio wave at a predetermined angle reaches the structure. Means for determining a path history, from among the rays radiated from the wave source and the rays branched by the structure,
Selecting means for selecting a ray passing through a predetermined receiving area at the reception point of the radio wave, a path history of the ray selected by the selecting means, and a path of the ray when the same path history is not stored. A route history table for recording a history, a calculating means for calculating the electric field intensity at the receiving point of each ray based on the route history stored in the route history table, and the electric field of all rays calculated by the calculating means. Means for adding the intensity.

According to a second aspect of the present invention, there is provided an electric field intensity calculating device, wherein first selecting means for selecting one of the rays emitted from the wave source of the radio wave at a predetermined angle, and the selected ray reaches the structure. Determining means for determining whether or not to perform, when the selected ray reaches the structure, a memory for storing a path history of each ray branched by the structure, and One is selected, and the second selecting means for causing the determining means to determine whether or not the ray reaches the structure again, and the ray is selected by the first selecting means or the second selecting means. Means for determining whether a ray passes through a predetermined reception area at the reception point of the radio wave, and a case where the ray passes through the reception area and the same route history as the ray is not recorded. And the path history of the ray A path history table to be recorded, a calculating means for calculating the electric field strength at the receiving point of each ray based on the path history stored in the path history table, and the electric field strengths of all the rays calculated by the calculating means. Means for adding.

According to the first aspect of the present invention, there is provided an electric field intensity calculation apparatus for obtaining a path history of each ray emitted from a wave source of a radio wave at a predetermined angle to a structure, and branching the ray radiated from the wave source and the structure. A ray that passes through a predetermined reception area at the reception point is selected from the rays thus obtained. If the same path history as the selected ray is not saved,
Record the path history of the ray in the path history table.

According to a second aspect of the present invention, there is provided an electric field intensity calculating apparatus for sequentially selecting each ray emitted from a wave source of a radio wave at a predetermined angle. When the selected ray reaches the structure, the path history of each ray branched by the structure is stored in the memory, and each branched ray is sequentially selected to determine whether the ray reaches the structure again. Judge. If the selected ray passes through a predetermined reception area at the radio wave receiving point and the same route history as that ray is not recorded, the route history of the ray is recorded in the route history table.

In the first or second aspect, the path history table includes a reflection surface, a transmission surface, and a reflection surface of a structure through which each ray passes.
The diffraction point is stored in association with each ray. However, when a plurality of rays having the same history reach the same reception area ΔS, only a single ray is recorded in the path history table. The electric field strength at the receiving point of each ray is calculated based on the path history stored in the path history table, and the calculated electric field strengths of all the rays are added, so that the electric field strengths of the rays of the same path are overlapped and added. Can be prevented.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 8 shows the configuration of the electric field strength calculation device according to the embodiment of the present invention. In FIG.
The CPU 12 controls the entire electric field intensity calculation apparatus and calculates the ray history and electric field intensity. ROM14
Stores a program to be executed by the CPU 12. R
The AM 16 stores the path history data 17 of the ray under calculation.

The electric field strength calculated by the CPU 12 is displayed on the display device 18 and output to the output device 20. The operation unit 24 performs input from an operator. An input / output control device (I / O) 26 is a CD-ROM drive device 28 or F
Data or a program is input from the D drive device 30. The program executed by the CPU 12 may be provided by a CD-ROM or an FD, read by the CD-ROM drive 28 or the FD drive 30, and installed in the HD (hard disk) 22 via the I / O 36. The program installed in the HD 22 is read as needed, stored in the RAM 16 and stored in the CPU 1.
2 is performed.

FIG. 9 is an explanatory diagram showing the relationship between the transmission point BS, the reception point P, and the structure Fj. The transmission point BS is a wave source such as a base station. A reception area centered on the reception point P is defined as ΔS. In the radio wave radiated from the transmission point BS, the i-th ray separated by a certain angle Δθ is defined as Ei. The j-th structure is defined as Fj. As shown in FIG. 10, the ray that has reached the structure Fj branches into a reflected wave and a transmitted wave. Furthermore, the ray that has reached the end of the structure Fj branches into a diffracted wave. The ray branched from ray Ei is Ei (Hk)
far. Here, Hk is the path history of the k-th ray branched from the ray Ei.

In FIG. 11, if reflection at the structure Fj is FjR, transmission is FjT, and diffraction is FjD, ray Ei (H1) has a path history H1 = F1R, ray Ei (H2) has a path history H2 = F1t, The ray Ei (H3) has a path history H3 = F1t, F2R, and the ray Ei (H4) has a path history H4 = F1t, F2t. These route histories are stored in the route history data 17. When a new ray arrives at the reception area ΔS, the path history of that ray is compared with the path histories Hk of all the rays that have already arrived. When there are a plurality of rays having the same path history, one ray is selected from the rays.

FIG. 12 is a flowchart illustrating a method of calculating the electric field intensity performed by the CPU 12. First, the transmission point BS and the reception area $ S are input from the operation unit 24. Next, the CPU 12 selects one ray radiated from the transmission point BS (S10), and determines whether or not the selected ray reaches the structure (S20). In this case, the position, shape, and the like of the structure are stored in a predetermined area of the HD 22 in advance. Then, when reaching the structure, each ray branched by the structure is registered in the route history data 17 (S30). Next, the route history so far and the route history (FjR, FjT, or Fj
D) is recorded in the route history data 17 of the RAM 16 in association with each ray (S40). Further, route history data 17
Among the unprocessed rays recorded in
One ray is selected (S50), and the process returns to S20.

If the selected ray does not reach the structure in S20, it is determined whether or not the selected ray reaches the reception area ΔS (S60). If it does not reach the reception area, the next ray is selected from the route history data in the RAM 16 (S55). However, if there is no unprocessed ray in the path history data 17, the next ray radiated from the BS is selected (S55). When it is determined in S60 that the selected ray reaches the reception area, it is determined whether or not the same path history as the path history of the selected ray is recorded in the path history table 23 of the HD 22 (S65). S65
If the same route history is recorded in the route history table 23, the next ray is selected (S55).

As shown in FIG. 13, rays having the same route history are not recorded in the route history table 23.
It is excluded from the subsequent calculation of the electric field strength (S90). S
In 65, if the same path history as the path history of the selected ray is not recorded in the path history table 23, the path history of the selected ray is recorded in the path history table 23.

Next, if there is an unprocessed ray, the process returns to S55 (S80). When the path histories of all the rays have been checked, the electric field strength is calculated using the path histories of the respective rays recorded in the path history table (S90), and the process ends.
According to the present embodiment, since only one ray of the same path history is recorded in the path history table 23, it is possible to prevent the electric field strengths due to the rays of the same path history from being redundantly added. Even when the reception area ΔS is wide, the electric field strengths are not added redundantly, so that the reception area ΔS can be set more easily than before.

[0021]

As is clear from the above description, according to the present invention, since only one ray of the same path history is recorded in the path history table 23, the electric field strength of the ray of the same path history is No overlap is added. For this reason, it is possible to improve the calculation accuracy of the electric field strength while maintaining the high-speed processing, which is an advantage of the launching method.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an outline of a ray tracing method.

FIG. 2 is an explanatory diagram illustrating a method of obtaining a ray trajectory by an image method.

FIG. 3 is an explanatory diagram illustrating a method of obtaining a ray trajectory by a conventional launching method.

FIG. 4 is an explanatory diagram for explaining the disadvantages of the conventional launching method.

FIG. 5 is an explanatory diagram illustrating a method of obtaining a trajectory of a ray that reaches a reception area.

FIG. 6 is an explanatory diagram for explaining a problem of the conventional launching method.

FIG. 7 is an explanatory diagram for explaining a problem of a conventional launching method.

FIG. 8 is a block diagram showing a configuration of an electric field strength measuring device.

FIG. 9 is an explanatory diagram showing a method of processing a route history.

FIG. 10 is an explanatory diagram illustrating a method of processing a route history.

FIG. 11 is an explanatory diagram showing a specific example of a ray route history.

FIG. 12 is a flowchart illustrating an operation of a CPU 12;

FIG. 13 is an explanatory diagram for explaining the effect of the electric field intensity measuring apparatus of the present invention.

[Explanation of symbols]

 12 CPU 14 ROM 16 RAM 18 Display device 20 Output device 22 HD 23 Route history table 24 Operation unit 26 I / O 28 CD-ROM drive device 30 FD drive device 40, 42, 44 Structure

Continuation of front page (56) References JP-A-7-212322 (JP, A) IEEE Trans. Veh. Technol. Vol. 43, No. 4, pp 955-969, 1994 (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 29/08 H04B 7/00

Claims (2)

(57) [Claims] 1. An electric field intensity calculation device for calculating the electric field intensity of a radio wave, comprising: means for obtaining a history of a path through which a ray radiated from a wave source of the radio wave at a predetermined angle passes through a structure; Selecting means for selecting a ray passing through a predetermined reception area at the reception point of the radio wave, from among the radiated rays and the rays branched by the structure, a path history of the ray selected by the selection means; When the same route history is not stored, a route history table that records the route history of the ray, and an electric field strength at the reception point of each ray are calculated based on the route history stored in the route history table. An electric field intensity calculation device, comprising: a calculation unit; and a unit for adding the electric field intensity of all rays calculated by the calculation unit. 2. An electric field intensity calculation device for calculating an electric field intensity of a radio wave, comprising: first selection means for selecting one of rays radiated from the wave source of the radio wave at a predetermined angle; Determining means for determining whether a ray reaches a structure, and a memory for storing a path history of each ray branched by the structure when the selected ray reaches the structure, A second selecting unit that selects one of the branched rays and causes the determining unit to determine whether or not the ray reaches the structure again; the first selecting unit or the second selecting unit; Means for judging whether or not the ray selected by the selecting means passes through a predetermined receiving area at the reception point of the radio wave; and a path history in which the ray passes through the receiving area, and the same path history as the ray. If not recorded, A route history table that records the route history of the ray, a calculating unit that calculates the electric field intensity at the reception point of each ray based on the route history stored in the route history table, and all calculated by the calculating unit. Means for adding the electric field strengths of the rays.