JP5418059B2 - Neighboring cell design apparatus, neighboring cell designing method and program - Google Patents

Description

  The present invention relates to a neighbor cell design apparatus, a neighbor cell design method, and a neighbor cell design method for designing neighbor cell information indicating a handover destination cell due to movement of a mobile terminal existing in the cell, which is a communication range of a base station apparatus, and Regarding the program.

In a mobile communication system, in order for a mobile terminal to continue communication while moving, it is necessary to perform a process of handover for sequentially switching a communication connection destination base station apparatus to another base station apparatus during the movement process. In order to realize the handover, a base station device cell (hereinafter referred to as an adjacent cell) that is a handover destination candidate for each base station device cell (hereinafter referred to as a target cell) in the base station control device. It is necessary to design appropriately. Here, “design” of an adjacent cell means whether another cell that is a candidate for an adjacent cell (hereinafter referred to as a candidate cell) is necessary or unnecessary in a certain target cell. Say to make a judgment. Hereinafter, the term “design” is used as the same meaning.
Handover can be realized by designing an appropriate neighboring cell and setting the designed neighboring cell in the base station controller. Here, the “setting” of the neighboring cell updates the correspondence relationship of the neighboring cell list in the neighboring cell list that is stored in the storage unit of the base station controller and stores the target cell and the neighboring cell in association with each other. Indicates processing.

  If the neighboring cell is not properly designed, the mobile terminal cannot be handed over to an appropriate cell when moving between cells, and communication disconnection or communication quality degradation may occur. In addition, since there is an upper limit on the number of neighboring cells that can be set for one target cell, cells that are highly likely to undergo handover are registered in the neighbor cell list without omission, and cells or handovers that are unlikely to undergo handover It is desirable to design an appropriate neighbor cell so that a cell with a high failure rate can be excluded from the neighbor cell list.

The neighbor cell design is performed at the time of initial setting when a new base station apparatus is installed and at the time of updating during operation of the base station apparatus.
Conventionally, the design of neighboring cells at the time of initial setting is based on the distance between the base station device to be designed for neighboring cells and the surrounding base station devices and the line-of-sight (presence of obstacles between base station devices). This is performed by extracting a cell in which the potential is expected as an adjacent cell.
In addition, the design of the adjacent cell at the time of updating is performed by performing travel measurement using an electric vehicle to collect information on the radio field intensity and determining the adjacent cell based on the information.

  In addition, since designing of neighboring cells by actual measurement takes time to collect radio wave intensity information, designing of neighboring cells using radio wave propagation simulation has also been performed. Specifically, the radio wave arrival range from the base station apparatus to which the target cell and the candidate cell belong is calculated using radio wave propagation simulation. Then, an area where the radio wave reachable range from the base station apparatus to which the target cell belongs and the radio wave reachable range from the base station apparatus to which the candidate cell belongs is estimated (hereinafter referred to as an overlap area), and the overlap area The candidate cell is extracted as an adjacent cell of the target cell when the size of the cell exceeds a predetermined threshold or when the number of used terminals expected in the overlap region exceeds the predetermined threshold.

  Patent Document 1 discloses a method for determining an installation position including the height direction of a base station apparatus using three-dimensional structure information.

JP 2003-274444 A

  However, when designing neighboring cells based on the measured value of the radio field intensity by the electric vehicle, only the two-dimensional radio wave condition on the ground surface can be grasped, so the overlap area that is observed only on the higher floors of the building is detected. There was a problem that could not be done. Also, when designing neighboring cells by radio wave propagation simulation, we ignored the higher-level handover and designed neighboring cells based on simulation of radio wave conditions on the two-dimensional plane showing the ground surface. Similar to the design, there was a problem that it was not possible to detect the overlap area observed only on the higher floors of the building.

Here, the reason why handover in a higher hierarchy has not been taken into consideration in the design of adjacent cells by the conventional radio wave propagation simulation will be described.
Conventionally, neighboring cells have been designed for the purpose of expanding the wireless area. During the period aimed at expanding the radio area, that is, the “rollout period”, it was important to broadly expand the radio area, so it was sufficient to roughly grasp the radio wave conditions near the ground by electrical measurement. .
However, in recent years, it has become a “spreading period” in which the wireless area reaches the whole area, and it has become necessary to set the wireless area for a dead zone that occurs locally.

  For this reason, as in Patent Document 1 described above, it is necessary to perform simulation of a three-dimensional radio wave condition including the height direction even in adjacent cell design, and to deal with a dead zone generated at a specific height. there were. However, only by obtaining radio wave information of a specific location, it has been impossible to design an appropriate adjacent cell in consideration of the upper limit of the number of adjacent cells that can be set for one target cell as described above.

  Conventionally, when communication quality is poor on a high floor of a building, the problem is solved by an ad hoc method of measuring the radio field intensity in a place with poor communication quality and redesigning the neighboring cell based on the measurement result. However, it is desired to design an adjacent cell so that high quality communication can be performed in advance on a high floor of a building.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an adjacent cell design apparatus and an adjacent cell design for designing adjacent cell information in consideration of an overlap region observed only at a high level of a building. It is to provide a method and a program.

The present invention has been made to solve the above-described problem, and is an adjacent cell design apparatus that designs an adjacent cell indicating a handover destination cell of a mobile terminal with respect to a cell that is a communication range of a base station apparatus. Te, based on the radio field intensity at a plurality of receiving points of the radio wave transmitted from the base station apparatus of multiple, radio waves and the neighboring cell candidate target cell is a handover source cell is transmitted from the base station apparatus belongs An overlap region estimation unit for calculating an overlap region indicating a region where radio waves transmitted from a base station apparatus to which a certain candidate cell belongs overlaps in the assumed presence region of the mobile terminal, and the overlap region estimation unit When the calculated overlap area size is larger than a predetermined threshold, an adjacency determination unit that determines that the candidate cell is an adjacent cell, and a determination result by the adjacency determination unit Characterized in that it and a neighboring cell design unit for designing the neighboring cells Zui.

The present invention also relates to an adjacent cell design method using an adjacent cell design apparatus for designing an adjacent cell indicating a handover destination cell of a mobile terminal with respect to a cell that is a communication range of a base station apparatus, and the overlap cell design method includes: region estimating unit, based on the radio field intensity at a plurality of receiving points of the radio wave transmitted from the base station apparatus of multiple, Telecommunications and the neighboring cell target cell is a handover source cell is transmitted from the base station apparatus belongs An overlap region indicating a region where radio waves transmitted from a base station apparatus to which a candidate cell that is a candidate belongs overlaps within an assumed region of presence of the mobile terminal is calculated, and an adjacency determining unit calculates the overlap region estimation If the size of the overlap area calculated by the unit is larger than a predetermined threshold, the candidate cell is determined to be an adjacent cell, and the adjacent cell design unit determines whether the adjacent cell is determined by the adjacent determination unit. The design of the neighboring cells based on, characterized in that.

Further, the present invention radio waves, to a cell which is a communication range of a base station apparatus, the neighboring cell design apparatus for designing a neighboring cell indicating a handover destination cell of the mobile terminal, transmitted from the base station apparatus of multiple The radio wave transmitted from the base station apparatus to which the target cell that is the handover source cell belongs and the radio wave transmitted from the base station apparatus to which the candidate cell that is a candidate for the adjacent cell belongs Is an overlap region estimation unit that calculates an overlap region indicating an overlap region within the assumed presence region of the mobile terminal, and the size of the overlap region calculated by the overlap region estimation unit is greater than a predetermined threshold An adjacent determination unit that determines that the candidate cell is an adjacent cell, and an adjacent cell design unit that designs an adjacent cell based on a determination result by the adjacent determination unit. Is a program to function.

  According to the present invention, since the adjacency determination unit estimates the overlap area on the assumed existence area of the mobile terminal, the neighbor cell information is designed in consideration of the overlap area observed only in the high hierarchy of the building. It can be carried out.

It is a schematic block diagram which shows the structure of the adjacent cell design apparatus by the 1st Embodiment of this invention. It is a 1st figure which shows the information which a radio wave information storage part memorize | stores. It is a figure which shows the information which an adjacent cell setting information storage part memorize | stores. It is a 1st flowchart which shows operation | movement of an adjacent cell design apparatus. It is a flowchart which shows operation | movement of the estimation process of an overlap area | region. It is a schematic block diagram which shows the structure of the adjacent cell design apparatus by the 2nd Embodiment of this invention. It is a figure which shows the information which a map information storage part memorize | stores. It is a figure which shows the information which a base station information storage part memorize | stores. It is a 2nd flowchart which shows operation | movement of an adjacent cell design apparatus. It is a schematic block diagram which shows the structure of the adjacent cell design apparatus by the 3rd Embodiment of this invention. It is a 2nd figure which shows the information which a radio wave information storage part memorize | stores. It is a figure which shows the information which a population distribution memory | storage part memorize | stores. It is a schematic block diagram which shows the structure of the adjacent cell design apparatus by the 4th Embodiment of this invention. It is a figure which shows the information which a hand-over statistics information storage part memorize | stores.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram showing a configuration of an adjacent cell design apparatus 100 according to the first embodiment of the present invention.
The adjacent cell design device 100 includes a radio wave information storage unit 101, a radio wave intensity acquisition unit 102, a target cell strength difference calculation unit 103, a candidate cell strength difference calculation unit 104, an overlap determination unit 105, an overlap region estimation unit 106, and an adjacent determination unit. 107, an adjacent cell setting information storage unit 108, and an adjacent cell design unit 109.
The radio wave information storage unit 101 stores radio wave strengths from a plurality of base station apparatuses at each reception point in the assumed presence area of the mobile terminal in association with the radio cell identifier and the latitude / longitude / altitude of the reception point. Yes. Here, the assumed presence area of the mobile terminal indicates each level of the ground surface and the building in the peripheral area of the target cell.
The radio wave intensity acquisition unit 102 receives from the radio wave information storage unit 101 the radio wave intensity from the base station apparatus to which the cell having the highest radio wave intensity at each reception point (hereinafter referred to as a dominant cell) belongs, and the cell to be designed for the adjacent cell. The radio field intensity from the base station apparatus to which the (target cell) belongs and the radio field intensity from the base station apparatus to which a cell (candidate cell) that is a candidate for an adjacent cell belongs are read out.
Target cell strength difference calculation section 103 calculates the difference between the radio field intensity from the base station apparatus to which the dominant cell belongs at each reception point and the radio field intensity from the base station apparatus to which the target cell belongs.
Candidate cell strength difference calculation section 104 calculates the difference between the radio field intensity from the base station apparatus to which the dominant cell belongs at each reception point and the radio field intensity from the base station apparatus to which the candidate cell belongs.
Based on the intensity difference calculated by the target cell strength difference calculation unit 103 and the strength difference calculated by the candidate cell strength difference calculation unit 104 at a certain reception point, the duplication determination unit 105 determines whether the target cell and the candidate cell at the reception point are Determine if there is any overlap.
The overlap region estimation unit 106 estimates the overlap region based on the presence or absence of cell duplication at each reception point.
The adjacency determination unit 107 determines that the candidate cell is an adjacent cell of the target cell when the area of the overlap region estimated by the overlap region estimation unit 106 is larger than a predetermined threshold.
The neighboring cell setting information storage unit 108 stores information stored in the base station controller as a neighboring cell of the target cell.
The adjacent cell design unit 109 designs an adjacent cell based on the determination result by the adjacent determination unit 107 and the information stored in the adjacent cell setting information storage unit 108, and performs an update command based on the designed adjacent cell by base station control By transmitting to the device, the neighboring cell information is set in the base station control device.

FIG. 2 is a first diagram illustrating information stored in the radio wave information storage unit 101.
As shown in FIG. 2, the radio wave information storage unit 101 includes a wireless cell identifier for identifying a cell, a latitude / longitude / altitude indicating a reception point in the assumed presence area of the mobile terminal, and a cell indicated by the wireless cell identifier. The radio wave intensity at the reception point from the base station apparatus to which it belongs is stored in association with a one-to-one relationship. That is, the radio wave information storage unit 101 stores the radio wave intensity using a combination of a wireless cell identifier, latitude, longitude, and altitude as a key.
Here, although the absolute value (unit: dBm) of the radio field intensity is stored as the radio field intensity in the radio wave information storage unit 101, the signal-to-interference noise ratio or the absolute value of the radio field intensity is used instead of the absolute value of the radio field intensity. Alternatively, it may be a Boolean value indicating whether the signal-to-interference / noise ratio exceeds a predetermined threshold. Here, latitude, longitude, and altitude are used as position information, but X, Y, and Z coordinates of a rectangular coordinate system such as a 19 coordinate system or a UTM coordinate system may be stored.

  Here, it is desirable that the altitude is stored in a plurality of hierarchies for a place having the same latitude and longitude. In particular, when the reception point is located in a building, it is stored in a plurality of hierarchies according to the height or hierarchy of the building so that the radio wave intensity from the low-rise part to the high-rise part of the building is memorized. It is desirable that Alternatively, when the altitude is stored in a single hierarchy for a place with the same latitude and longitude, it is desirable that the altitude is stored at different heights according to characteristics such as the height of the building.

  Further, the reception points stored in the radio wave information storage unit 101 may be grid points obtained by dividing the assumed existence region of the mobile terminal in predetermined unit lengths in the latitude, longitude, and altitude directions. The points on the area may be extracted at random. At this time, the radio wave information storage unit 101 may store reception points with a coarse density (resolution) according to the attributes of buildings and landforms (for example, population density and height difference). For example, in places where there are many calls and communications using mobile phones such as high floors of office buildings, the interval between grid points that make up the reception point is reduced, and in places where communication is expected to be low such as in Tabata, the interval between grid points is reduced. By increasing the size, it is possible to secure the estimation accuracy of the overlap area in a place where there are many calls while reducing the amount of calculation.

FIG. 3 is a diagram illustrating information stored in the neighboring cell setting information storage unit 108.
As shown in FIG. 3, the neighboring cell setting information storage unit 108 stores a wireless cell identifier indicating the target cell and an adjacent cell identifier indicating the neighboring cell in association with each other in a many-to-many relationship.

Then, in adjacent cell design apparatus 100, overlap region estimation section 106 has the base station to which the target cell belongs based on the radio field strength information indicating the radio field intensity from the base station apparatus to which a plurality of cells at a plurality of reception points belong. An overlap region is estimated that indicates a region where a radio wave from a station device and a radio wave from a base station device to which a candidate cell belongs overlap within the assumed existence region of the mobile terminal. Next, the adjacency determination unit 107 determines that the candidate cell is an adjacent cell when the size of the overlap region estimated by the overlap region estimation unit 106 is larger than a predetermined threshold, and the adjacent cell design unit 109 An adjacent cell is designed based on the determination result by the adjacent determination unit 107.
Thereby, the adjacent cell design apparatus 100 can design adjacent cell information in consideration of the overlap area observed only in the high hierarchy of the building.

Next, the operation of the adjacent cell design apparatus 100 will be described.
FIG. 4 is a first flowchart showing the operation of the adjacent cell design apparatus 100.
Before performing the adjacent cell design operation by the adjacent cell design apparatus 100, the radio field intensity at each reception point is measured in advance, and the radio wave information storage unit 101 stores the radio field intensity information obtained by the actual measurement. Shall be kept.
When the user designates the target cell and operates the adjacent cell design apparatus 100, when the adjacent cell design apparatus 100 starts an adjacent cell design operation with respect to the target cell, first, the radio wave intensity acquisition unit 102 includes a radio wave information storage unit 101, a radio cell identifier for identifying a cell, a latitude / longitude / altitude indicating a reception point in the assumed presence area of the mobile terminal, and a radio wave intensity corresponding to the radio wave intensity at the reception point in a one-to-one relationship Information is read (step S1). Next, the radio field strength acquisition unit 102, the target cell strength difference calculation unit 103, the candidate cell strength difference calculation unit 104, the overlap determination unit 105, and the overlap region estimation unit 106 cooperate to form a target cell and a candidate cell. A process for estimating the overlap region is performed (step S2). At this time, the candidate cell is selected from cells existing in the area around the target cell. The details of the overlap area estimation process in step S2 will be described later.

  When the overlap region estimation unit 106 estimates the overlap region, the adjacency determination unit 107 calculates the area of the estimated overlap region (step S3). Here, since the estimated overlap area is composed of the ground surface of the peripheral area of the target cell and each level of the building, the sum of the areas is calculated as the area of the overlap area.

Next, the adjacency determination unit 107 determines whether or not the calculated area of the overlap region is equal to or greater than a predetermined threshold (step S4).
When the adjacency determination unit 107 determines that the area of the overlap region is equal to or larger than the predetermined threshold (step S4: YES), the adjacency determination unit 107 determines that the target cell and the candidate cell are adjacent to each other, The neighboring cell design unit 109 determines whether or not the candidate cell is unregistered in the neighboring cell setting information storage unit 108 (step S5). When the neighboring cell design unit 109 determines that the candidate cell is not registered in the neighboring cell setting information storage unit 108 (step S5: YES), the neighboring cell design unit 109 sets the identifier of the candidate cell as the neighbor cell identifier. Extracted as a cell to be added to the list (step S6). At this time, the adjacent cell design unit 109 stores the extracted candidate cell identifier in the additional cell storage area of the internal memory.

  On the other hand, when the adjacency determination unit 107 determines that the area of the overlap region is less than the predetermined threshold (step S4: NO), the adjacency determination unit 107 determines that the target cell and the candidate cell are not adjacent to each other. Then, the neighboring cell design unit 109 determines whether or not the candidate cell is registered in the neighboring cell setting information storage unit 108 (step S7). When the neighbor cell design unit 109 determines that the candidate cell is registered in the neighbor cell setting information storage unit 108 (step S7: YES), the neighbor cell design unit 109 sets the identifier of the candidate cell to the neighbor cell identifier. A cell to be excluded from the list is extracted (step S8). At this time, the adjacent cell design unit 109 stores the extracted candidate cell identifier in the excluded cell storage area of the internal memory.

When the neighboring cell design unit 109 determines in step S5 that the candidate cell is registered in the neighboring cell setting information storage unit 108 (step S5: NO), the neighboring cell design unit 109 sets the candidate cell identifier in step S6. If extracted, the neighboring cell design unit 109 determines in step S7 that the candidate cell is not registered in the neighboring cell setting information storage unit 108 (step S7: NO), or the neighboring cell design unit 109 in step S8. When the candidate cell identifiers are extracted, the processes in steps S2 to S8 are executed using other cells stored in the radio wave information storage unit 101 as candidate cells until the determination on all candidate cells is completed (step S9).
When adjacent determination is performed on all candidate cells by the processes in steps S2 to S9, that is, when the design of the adjacent cell with respect to the target cell is completed, the adjacent cell design unit 109 stores the additional cell storage area of the internal memory. The candidate cell is added to the neighboring cell list of the target cell, and an update command indicating that the candidate cell stored in the excluded cell storage area of the internal memory is excluded from the neighboring cell list of the target cell is generated and transmitted to the base station controller (Step S10). That is, the neighboring cell is set.

  In addition, although the operation shown here is an operation when an adjacent cell is set in advance in the target cell, it is an initial setting time when a base station apparatus is newly installed, and an adjacent cell is set in the target cell. Even if not, it can be operated. In this case, since the adjacent cell setting information storage unit 109 does not store information on adjacent cells, the determination in step S5 is always YES, and the determination in step S7 is always NO. Therefore, when designing an adjacent cell only in a state where no adjacent cell is set as the target cell, the processes in steps S5, S7, and S8 do not have to be performed.

Next, the details of the overlap region estimation process in step S2 described above will be described.
FIG. 5 is a flowchart showing the operation of the overlap area estimation process.
When the radio wave intensity acquisition unit 102 reads out the radio wave intensity information shown in FIG. 2 in step S1 described above or starts the overlap region estimation process using another cell as a candidate cell by the loop of step S9, the radio wave intensity acquisition unit 102 reads out the radio wave intensity from the base station apparatus to which the dominant cell at a certain reception point A belongs from the radio wave intensity information read out in step S1 (step S101). As described above, the dominant cell is a cell of the base station apparatus having the highest radio wave intensity at the reception point. Next, the radio wave intensity acquisition unit 102 reads the radio wave intensity from the base station apparatus to which the target cell belongs at a certain reception point A from the radio wave intensity information (step S102). Next, the radio field intensity acquisition unit 102 reads the radio field intensity at a certain reception point A from the base station apparatus to which the candidate cell for which the overlap area is estimated belongs, from the radio field intensity information (step S103).
In steps S101 to S103, the radio field intensity acquisition unit 102 reads out the radio field intensity from the base station apparatus to which the dominant cell belongs at the same reception point, the base station apparatus to which the target cell belongs, and the base station apparatus to which the candidate cell belongs. Shall.

  When the radio field intensity acquisition unit 102 reads out the radio field intensity from the base station apparatus to which the dominant cell, the target cell, and the candidate cell belong in steps S101 to S103, the target cell intensity difference calculation unit 103 determines that the target cell belongs to the base station apparatus. The radio field intensity difference D1 between the radio field intensity from the base station apparatus to which the dominant cell belongs is calculated (step S104). Similarly, candidate cell strength difference calculation section 103 calculates a radio field strength difference D2 between the radio field strength from the base station apparatus to which the candidate cell belongs and the radio field strength from the base station apparatus to which the dominant cell belongs (step S105).

  When the radio field intensity differences D1 and D2 are calculated in steps S104 and S105, the duplication determination unit 105 determines the radio field intensity difference D1 between the radio field intensity from the base station apparatus to which the target cell belongs and the radio field intensity from the base station apparatus to which the dominant cell belongs. Then, it is determined whether or not the radio field intensity difference D2 between the radio field intensity from the base station apparatus to which the candidate cell belongs and the radio field intensity from the base station apparatus to which the dominant cell belongs is equal to or less than a predetermined threshold (step S106). The overlap determination unit 105 determines that the target cell and the candidate cell overlap each other when it is determined that both the radio field intensity differences D1 and D2 are equal to or smaller than the predetermined threshold (step S106: YES) (step S107). On the other hand, when it is determined that at least one of the radio field intensity differences D1 and D2 is equal to or greater than a predetermined threshold (step S106: NO), the overlap determination unit 105 determines that the target cell and the candidate cell do not overlap. (Step S108).

Here, the reason why the presence / absence of duplication is determined by the processing of steps S106 to S108 will be described.
As described above, the dominant cell is the cell having the highest radio wave intensity at the reception point. Therefore, the difference in radio wave intensity between the other cell and the dominant cell means that the other cell becomes a dominant cell as it moves. This indicates that there is a high possibility that a handover will occur between the other cell and the dominant cell. Conversely, the fact that the difference in radio field strength between another cell and the dominant cell is large means that the probability that the other cell will become a dominant cell with movement is low, so the mobile terminal is located in the dominant cell, and the cell Indicates that the possibility of handover is low.
Therefore, even if the radio field intensity difference between the target cell and the candidate cell is small, if the radio field intensity difference between the target cell and the candidate cell and the dominant cell is large, the mobile terminal is likely to be in the dominant cell. The probability of handover occurring is low.
Therefore, by determining that the target cell and the candidate cell overlap only when the radio field strength from the base station apparatus to which the target cell, the candidate cell, and the dominant cell belong is close, a candidate cell with a low occurrence probability of handover can be obtained. It can prevent being determined as an adjacent cell.
When either the target cell or the candidate cell is a dominant cell, either of the radio field intensity differences D1 or D2 is 0. Equivalent to determining whether or not.

When the duplication determination unit 105 determines whether or not there is duplication in step S107 or S108, with respect to other reception points stored in the radio wave information storage unit 101 until the determination of whether or not there is duplication for all reception points is completed. The processes of steps S101 to S108 are executed (step S109).
When it is determined whether or not there is an overlap for all reception points by the processes in steps S101 to S109, the overlap area estimation unit 106 estimates an overlap area (step S110). Specifically, the overlap region estimation unit 106 extracts reception points determined to overlap the target cell and the candidate cell from reception points having the same altitude, and performs an interpolation process on the reception points and others. By estimating the boundary line with the receiving point, the area within the boundary line is estimated as the overlap area. By this processing, the overlap area estimation unit 106 estimates an overlap area for each altitude. When the reception point is a point on the ground surface, it is desirable to estimate the overlap region as one surface even if the altitudes are different.
Then, using the estimated overlap region, it is determined whether or not the candidate cell is an adjacent cell by the processing after step S3 described above.

  As described above, according to the present embodiment, since the overlap area is calculated in a plurality of hierarchies using radio wave information stored in the plurality of hierarchies, it can appropriately cope with a handover occurring only in a high hierarchy of the building. can do. As a result, a cell that has not been grasped as a neighbor cell in the conventional method can be extracted and registered in the neighbor cell list, and the probability of occurrence of a handover failure can be reduced.

In the present embodiment, a case has been described in which the process of steps S106 to S110 estimates a set of points having close radio wave strengths from the base station apparatus to which the target cell, candidate cell, and dominant cell belong as an overlap region. It is not limited to this. For example, although the accuracy is reduced due to the above-described reason, a set of points having a small radio field intensity difference between the target cell and the candidate cell may be estimated as the overlap region.
Alternatively, a set of points where the difference in radio field intensity from the two target cells has a predetermined value may be connected by a line, and the line may be used as an overlap region. In this case, in step S3, not the area of the overlap region, but the length is calculated, and in step S4, it is determined whether or not the length is equal to or greater than a predetermined threshold value. It will be judged.

  Further, in the present embodiment, the case where the neighboring cell design unit 109 performs the design and setting of the neighboring cell has been described. However, the present invention is not limited to this. For example, the neighboring cell design unit 109 performs only the design of the neighboring cell. An apparatus or an administrator may set adjacent cells based on design contents.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to the drawings.
The second embodiment is an example in which radio wave intensity information is not prepared, radio wave propagation is estimated by simulation, and adjacent cells are designed based on this result.
FIG. 6 is a schematic block diagram showing the configuration of the neighboring cell design device 100 according to the second embodiment of the present invention.
The neighboring cell design device 100 according to the second embodiment replaces the radio wave information storage unit 101 and the radio wave intensity acquisition unit 102 of the neighboring cell design device 100 according to the first embodiment, and stores a map information storage unit 111 and a base station information storage. Unit 112 and radio wave intensity calculation unit 113.

The map information storage unit 111 stores information such as topography and buildings as three-dimensional object information in association with position information of the peripheral area of the target cell.
The base station information storage unit 112 stores information on base station apparatuses existing in the peripheral area of the target cell.
The radio wave intensity calculation unit 113 performs radio wave propagation estimation using information stored in the map information storage unit 111 and the base station information storage unit 112.

FIG. 7 is a diagram showing information stored in the map information storage unit 111.
As shown in FIG. 7, the map information storage unit 111 stores an object identifier indicating a three-dimensional object, a vertex identifier indicating a vertex of the three-dimensional object, and the latitude / longitude / altitude of the vertex. For example, when the three-dimensional object indicates terrain, it is stored as the altitude of the ground surface corresponding to the latitude and longitude in association with the vertex identifier. When the three-dimensional object indicates a building, the vertex information of the polygon of the building is stored as latitude / longitude / altitude in association with the vertex identifier.
Here, latitude, longitude, and altitude are used as position information, but X, Y, and Z coordinates of a rectangular coordinate system such as a 19 coordinate system or a UTM coordinate system may be stored.

FIG. 8 is a diagram illustrating information stored in the base station information storage unit 112.
As shown in FIG. 8, the base station information storage unit 112 includes, for each base station device, a base station identifier indicating the base station device, a radio cell identifier indicating a cell belonging to the base station device, and an installation position of the base station device. The latitude / longitude shown, the frequency of the transmitted radio wave, the transmission power capacity, the antenna height, the antenna pattern, the antenna azimuth angle, and the antenna tilt angle are stored in association with each other.

Next, the operation of the adjacent cell design apparatus 100 will be described.
FIG. 9 is a second flowchart showing the operation of the adjacent cell design apparatus 100. Note that the same processing as in the first embodiment will be described using the same reference numerals.
When the adjacent cell design device 100 starts an adjacent cell design operation for the target cell, first, the radio wave intensity calculation unit 113 reads the map information of the peripheral area of the target cell from the map information storage unit 111 (step S11). Next, the radio wave intensity calculation unit 113 reads out information on base station devices existing in the peripheral area of the target cell from the base station information storage unit 112 (step S12).

  Next, the radio wave intensity calculation unit 113 performs radio wave propagation estimation based on the map information and the information of the base station apparatus, deterministically considering the inside and outside of the line of sight of the base station apparatus, and the base station apparatus to which a certain cell belongs The radio field intensity in the assumed existence area of the mobile terminal on the map information from is calculated (step S13). Specifically, the radio wave intensity calculation unit 113 first calculates the radio wave intensity by using each vertex of a three-dimensional object stored as terrain in the map information as a reception point by radio wave propagation estimation. Next, the radio wave intensity calculation unit 113 divides the three-dimensional object stored as the building in the map information into a plurality of layers in the height direction, and divides each division surface in a predetermined unit length in the latitude and longitude directions. The radio field intensity is calculated using the grid points separated by as reception points. At this time, it is desirable that the reception points in the building are defined by the number of hierarchies corresponding to the height or the number of times of the building.

  The reception point is the surface of the 3D object stored as terrain in the map information or the divided surface when the 3D object stored as building in the map information is divided into multiple layers in the height direction. What was extracted at random from the top may be used. Moreover, you may change the coarse density (resolution) according to the attribute (for example, population density, height difference, etc.) of a building or topography. For example, in places where there are many calls and communications using mobile phones such as high floors of office buildings, the interval between grid points that make up the reception point is reduced, and in places where communication is expected to be low such as in Tabata, the interval between grid points is reduced. By increasing the size, it is possible to secure the estimation accuracy of the overlap area in a place where there are many calls while reducing the amount of calculation.

  Examples of radio wave propagation estimation methods by the radio wave intensity calculation unit 113 include a ray tracing method, a UTF (Uniform Theory of Diffraction) method, and a PO (Physical Optics) method. Or, deterministically determine the line of sight from the base station device, and if the determination result is within line of sight, use the free space propagation loss formula or the planar ground reflection formula, and if not, the free space propagation loss formula Or you may calculate using the thing which added the additional loss to the plane ground reflection type. Further, based on statistical methods such as the Okumura-Kashiwa formula and Sakagami formula, a method may be used in which different offsets are given to the results obtained from these formulas within and outside the line of sight.

In step S13, when the radio field intensity at the reception point on the map information from the base station apparatus to which the cell to which the cell belongs is calculated is calculated, the base station information is stored until the calculation of the radio field intensity is completed for all the cells. The process of step S13 is performed with respect to the cell of the other base station apparatus which the part 112 memorize | stores (step S14).
Next, the radio wave intensity acquisition unit 102, the target cell intensity difference calculation unit 103, the candidate cell intensity difference calculation unit 104, the overlap determination unit 105, and the overlap region estimation unit 106 cooperate through the processes in steps S101 to S110 described above. Then, a process for estimating an overlap area between the target cell and a certain candidate cell is performed (step S2). In the first embodiment, the radio wave intensity is read from the radio wave information storage unit 101 in the processes of steps S101 to S110. However, in the present embodiment, the radio wave intensity calculated from the radio wave intensity calculation unit 113 is read.

When the overlap region estimation unit 106 estimates the overlap region, the adjacency determination unit 107 calculates the area of the estimated overlap region (step S3). Next, the adjacency determination unit 107 determines whether or not the calculated area of the overlap region is equal to or greater than a predetermined threshold (step S4).
When the adjacency determination unit 107 determines that the area of the overlap region is equal to or larger than the predetermined threshold (step S4: YES), the adjacency determination unit 107 determines that the target cell and the candidate cell are adjacent to each other, The neighboring cell design unit 109 determines whether or not the candidate cell is unregistered in the neighboring cell setting information storage unit 108 (step S5). When the neighboring cell design unit 109 determines that the candidate cell is not registered in the neighboring cell setting information storage unit 108 (step S5: YES), the neighboring cell design unit 109 sets the identifier of the candidate cell as the neighbor cell identifier. Extracted as a cell to be added to the list (step S6). At this time, the adjacent cell design unit 109 stores the extracted candidate cell identifier in the additional cell storage area of the internal memory.

  On the other hand, when the adjacency determination unit 107 determines that the area of the overlap region is less than the predetermined threshold (step S4: NO), the adjacency determination unit 107 determines that the target cell and the candidate cell are not adjacent to each other. Then, the neighboring cell design unit 109 determines whether or not the candidate cell is registered in the neighboring cell setting information storage unit 108 (step S7). When the neighbor cell design unit 109 determines that the candidate cell is registered in the neighbor cell setting information storage unit 108 (step S7: YES), the neighbor cell design unit 109 sets the identifier of the candidate cell to the neighbor cell identifier. A cell to be excluded from the list is extracted (step S8). At this time, the adjacent cell design unit 109 stores the extracted candidate cell identifier in the excluded cell storage area of the internal memory.

When the neighboring cell design unit 109 determines in step S5 that the candidate cell is registered in the neighboring cell setting information storage unit 108 (step S5: NO), the neighboring cell design unit 109 sets the candidate cell identifier in step S6. If extracted, the neighboring cell design unit 109 determines in step S7 that the candidate cell is not registered in the neighboring cell setting information storage unit 108 (step S7: NO), or the neighboring cell design unit 109 in step S8. Extract the candidate cell identifiers, the radio wave information calculation unit 113 calculates the power intensity from the base station apparatus to which the other cells belong, calculated by the radio wave information calculation unit 113, from the base station apparatus to which the candidate cell belongs. Steps S2 to S8 are executed as power intensity (step S9).
When adjacent determination is performed for all candidate cells by the processes of steps S2 to S9 (when the adjacent cell design is completed), the adjacent cell design unit 109 targets candidate cells stored in the additional cell storage area of the internal memory. An update command indicating that the candidate cell stored in the excluded cell storage area of the internal memory is excluded from the adjacent cell list of the target cell is generated and transmitted to the base station controller (step S10). ).

As described above, according to the present embodiment, since the overlap area is calculated in a plurality of hierarchies using the radio wave information calculated for the plurality of hierarchies, the radio wave propagation situation in the area where the radio wave condition cannot be grasped is calculated. Based on this, it is possible to design adjacent cells. As a result, the probability of occurrence of a handover failure in a place where it is difficult to grasp the radio wave condition can be reduced.
In the present embodiment, the case where the neighboring cell is designed without using the actual measurement value of the radio wave information has been described. However, the present invention is not limited to this. For example, the actual radio wave information and the radio wave intensity calculated by the radio wave propagation estimation May be used together to design adjacent cells.

  Further, in the present embodiment, the case where the neighboring cell design unit 109 performs the design and setting of the neighboring cell has been described. However, the present invention is not limited to this. For example, the neighboring cell design unit 109 performs only the design of the neighboring cell. An apparatus or an administrator may set adjacent cells based on design contents.

(Third embodiment)
In the third embodiment, an adjacent cell is not determined based on the size of the overlap region, but the size of the overlap region is weighted, and the adjacent cell is determined based on the result value. It is.
FIG. 10 is a schematic block diagram showing the configuration of the neighboring cell design device 100 according to the third embodiment of the present invention.
The neighboring cell design device 100 according to the third embodiment has different contents stored in the radio wave information storage unit 121 of the neighboring cell design device 100 according to the first embodiment, and further includes a population distribution storage unit 122 and a weighting unit 123. It is.
The radio wave information storage unit 121 further stores data indicating reception point attributes in addition to the radio wave information storage unit 101 according to the first embodiment.
The population distribution storage unit 122 stores a population distribution at a reception point having the attribute in association with the attribute of the reception point.
The weighting unit 123 calculates a value obtained by multiplying the area of the overlap region by the population distribution stored in the population distribution storage unit 122.

FIG. 11 is a second diagram illustrating information stored in the radio wave information storage unit 121.
As shown in FIG. 11, the radio wave information storage unit 121 includes a radio cell identifier indicating a cell, a latitude / longitude / altitude indicating a reception point in the assumed existence area of the mobile terminal, a radio wave intensity at the reception point, and the reception Point attributes are stored in association with one-to-one relationships.
Here, the attribute of the reception point indicates the attribute of the building or the terrain where the reception point is located. For example, values such as “office building”, “house”, “field”, and “road” are stored. The

FIG. 12 is a diagram illustrating information stored in the population distribution storage unit 122.
As shown in FIG. 12, the population distribution storage unit 122 stores a population distribution at a reception point having the attribute in association with the attribute of the reception point. Here, it is desirable to use a statistically obtained value as the value of the population distribution.

Next, the operation of the adjacent cell design apparatus 100 will be described.
When the adjacent cell design device 100 calculates the area of the overlap region by the same method as in the first embodiment (step S3 in the first embodiment), the weighting unit 123 reads the overlap region from the radio wave information storage unit 121. Each attribute of the reception point included in is read. Next, the weighting unit 123 reads the population distribution corresponding to each attribute from the population distribution storage unit 122. Next, the weighting unit 123 calculates the average value of the weights of the reception points included in the overlap region. Specifically, it is possible to calculate the sum of the weights of the reception points included in the overlap region and divide the sum of the weights by the number of reception points. Next, the weighting unit 123 multiplies the calculated average value of weights by the area of the overlap region. This makes it possible to calculate a value indicating the likelihood of occurrence of handover in the overlap area.
Next, the adjacency determination unit 107 determines whether or not the area of the overlap region weighted by the weighting unit 123 is greater than or equal to a predetermined threshold (step S4 in the first embodiment).
The subsequent processing is the same as in the first embodiment.

  As a result, neighboring cells can be designed in consideration of not only the overlap area but also the frequency of handover, so the weight of areas where population is dense increases even if the area size is small. Therefore, the probability of occurrence of a handover failure at a location where frequent handovers occur can be reduced.

  In the present embodiment, the case where the overlap area is weighted using the population distribution has been described, but an index other than the population distribution may be used as long as it is an index based on the attribute of the building or the terrain. For example, the number of mobile phone users may be estimated from the attributes.

(Fourth embodiment)
The fourth embodiment is an example in which candidate cells are determined after narrowing down candidate cells based on handover statistical information.
FIG. 13 is a schematic block diagram showing the configuration of the neighboring cell design device 100 according to the fourth embodiment of the present invention.
The neighboring cell design apparatus 100 according to the fourth embodiment further includes a handover statistical information storage unit 131 and a candidate cell extraction unit 132 in addition to the neighboring cell design apparatus 100 according to the second embodiment.
The handover statistical information storage unit 131 stores the statistical information of handover of all cell sets in the peripheral area of the target cell.
FIG. 14 is a diagram illustrating information stored in the handover statistical information storage unit 131.
As shown in FIG. 14, the handover statistical information storage unit 131 stores the number of handover occurrences and the number of handover failures in association with two sets of cells.
The candidate cell extraction unit 132 extracts candidate cells based on the handover statistical information and the radio wave propagation estimation.

Next, the operation of the adjacent cell design apparatus 100 will be described.
When the neighbor cell design apparatus 100 starts the neighbor cell design operation for the target cell, first, the candidate cell extraction unit 132, from the handover statistical information storage unit 131, the radio cell identifier is the identifier of the target cell, The neighbor cell identifier whose handover occurrence count or handover failure count is equal to or greater than a predetermined threshold is read. Next, the candidate cell extraction unit 132 acquires map information from the map information storage unit 111, acquires base station information from the base station information storage unit 112, and reads the central part of the read neighboring cell identifier or a building near the center. Radio wave propagation is estimated using the higher floor of the object as the transmission point, and the radio wave reach is estimated. Note that the radio wave propagation estimation method used here may be a method in which the line-of-sight used in the second embodiment is deterministically determined and radio wave propagation estimation is performed based on the determination result. Next, candidate cell extraction section 132 extracts a base station device that exists within the estimated radio wave reachable range. And the candidate cell extraction part 132 extracts the cell which belongs to the said base station apparatus as a candidate cell. In other words, a cell belonging to a base station apparatus that exists within the estimated radio wave reachability range is considered to be a cell that reaches the transmission point of radio wave propagation estimation from the target of radio wave propagation. It can be said that narrowing down is effective.
When the candidate cell extraction unit narrows down candidate cells, the process after step S11 of the second embodiment is performed on each of the narrowed down candidate cells to design and set neighboring cells. It can be performed.
As described above, according to the present embodiment, it is possible to reduce the amount of calculation by extracting the cells to be adjacently determined in advance, and it is possible to design the adjacent cells at high speed.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above-described configuration, and various modifications are made without departing from the scope of the present invention. It is possible.
For example, in the above-described embodiment, the case where the neighboring cell design device 100 and the base station control device are separate devices and the neighboring cell design device 100 outputs a command for updating the neighboring cell list of the base station control device is described. However, the present invention is not limited to this, and the base station control device may mount the adjacent cell design device 100 inside.
Further, each processing unit or each storage unit of the adjacent cell design device 100 may be provided remotely via a network.

  The above-described neighboring cell design apparatus 100 has a computer system inside. The operation of each processing unit described above is stored in a computer-readable recording medium in the form of a program, and the above processing is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  DESCRIPTION OF SYMBOLS 100 ... Adjacent cell design apparatus 101 ... Radio wave information memory | storage part 102 ... Radio wave intensity acquisition part 103 ... Target cell intensity difference calculation part 104 ... Candidate cell intensity difference calculation part 105 ... Overlapping determination part 106 ... Overlap area estimation part 107 ... Adjacent determination Unit 108: Neighboring cell setting information storage unit 109 ... Neighboring cell design unit

Claims (10)

An adjacent cell design device that designs an adjacent cell indicating a handover destination cell of a mobile terminal with respect to a cell that is a communication range of a base station device,
Based on the radio field intensity at a plurality of receiving points of the radio wave transmitted from the base station apparatus of multiple candidates for Telecommunications and the neighboring cell target cell is a handover source cell is transmitted from the base station apparatus belongs candidate An overlap area estimation unit that calculates an overlap area indicating an area in which radio waves transmitted from a base station apparatus to which a cell belongs overlaps within the assumed existence area of the mobile terminal;
An adjacent determination unit that determines that the candidate cell is an adjacent cell when the size of the overlap region calculated by the overlap region estimation unit is greater than a predetermined threshold;
An adjacent cell design unit for designing an adjacent cell based on a determination result by the adjacent determination unit;
An adjacent cell design apparatus comprising:   The adjacent cell design apparatus according to claim 1, wherein the assumed existence area of the mobile terminal includes a divided surface and a ground surface when the building is divided in a height direction. For each of the plurality of the candidate cells, subjected to the sight and out deterministically considering radio propagation estimation between the base station apparatus target cell belongs and the base station apparatus to which the candidate cell belongs, a plurality of the candidate cells A radio field strength calculating unit that calculates a radio field strength at a reception point within the assumed existence area of the mobile terminal from the base station apparatus to which the candidate cell belongs ,
3. The adjacent cell according to claim 1, wherein the overlap area estimation unit calculates the overlap area based on the radio field intensity calculated by the radio field intensity calculation unit. Design equipment. Before SL radio field intensity from a plurality of the largest base station radio intensity at each receiving point, reading the radio field intensity from the base station apparatus radio strength, and the candidate cell belongs from the target cell base station apparatuses belonging Radio wave intensity acquisition unit,
Target cell strength difference for calculating the strength difference between the radio field strength of the base station device with the highest radio field strength read by the radio field strength acquisition unit and the radio field strength from the base station device to which the target cell read by the radio field strength acquisition unit belongs A calculation unit;
Candidate cell strength difference for calculating a strength difference between the radio field strength of the base station apparatus having the highest radio field intensity read by the radio field intensity acquisition unit and the radio field intensity from the base station apparatus to which the candidate cell read by the radio field intensity acquisition unit belongs A calculation unit;
When the intensity difference calculated by the target cell intensity difference calculation unit and the intensity difference calculated by the candidate cell intensity difference calculation unit are equal to or less than a predetermined threshold, the target cell and the candidate cell overlap at the reception point. A duplicate determination unit that determines that the
With
The overlap region estimation unit calculates an overlap region based on a plurality of reception points determined by the overlap determination unit to overlap the target cell and the candidate cell;
The adjacent cell design apparatus according to any one of claims 1 to 3, wherein The overlap area estimation unit calculates the overlap area based on the radio wave intensity at the reception point of coarse density according to the terrain attribute ,
The adjacent cell design apparatus according to any one of claims 1 to 4, wherein the apparatus is a neighboring cell design apparatus. The adjacency determination unit determines that the candidate cell is an adjacent cell when a value obtained by multiplying the size of the overlap area by a weight according to the terrain of the overlap area is greater than a predetermined threshold value.
6. The adjacent cell design apparatus according to any one of claims 1 to 5, wherein Deterministically determine the line-of-sight from the base station device to which the target cell belongs, and includes a reach range calculation unit that calculates the reach of radio waves from a certain point in the target cell based on the determination result,
The candidate cell is a cell of a base station device existing within the reach range calculated by the reach range calculation unit,
The adjacent cell design apparatus according to any one of claims 1 to 6, wherein The reach range calculation unit determines a point to calculate the reach range of radio waves based on the statistical information of handover,
The adjacent cell design apparatus according to claim 7, wherein: An adjacent cell design method using an adjacent cell design device that designs an adjacent cell indicating a handover destination cell of a mobile terminal with respect to a cell that is a communication range of a base station device,
Overlapping region estimation unit, on the basis of the radio field intensity at a plurality of receiving points of the radio wave transmitted from the base station apparatus of multiple, and radio waves target cell is a handover source cell is transmitted from the base station apparatus belongs Calculate an overlap area indicating an area where radio waves transmitted from a base station apparatus to which a candidate cell that is a candidate for an adjacent cell overlaps in the assumed existence area of the mobile terminal,
The adjacent determination unit determines that the candidate cell is an adjacent cell when the size of the overlap region calculated by the overlap region estimation unit is larger than a predetermined threshold,
The adjacent cell design unit designs the adjacent cell based on the determination result by the adjacent determination unit.
An adjacent cell design method characterized by the above. An adjacent cell design device that designs an adjacent cell indicating a handover destination cell of a mobile terminal with respect to a cell that is a communication range of a base station device,
Based on the radio field intensity at a plurality of receiving points of the radio wave transmitted from the base station apparatus of multiple candidates for Telecommunications and the neighboring cell target cell is a handover source cell is transmitted from the base station apparatus belongs candidate An overlap region estimation unit that calculates an overlap region indicating a region where radio waves transmitted from a base station apparatus to which a cell belongs overlaps within the assumed existence region of the mobile terminal;
An adjacent determination unit that determines that the candidate cell is an adjacent cell when the size of the overlap region calculated by the overlap region estimation unit is greater than a predetermined threshold;
An adjacent cell design unit for designing an adjacent cell based on a determination result by the adjacent determination unit,
Program to function as.

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