JP2016039404A - Base station installation place determination device, base station installation place determination method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for determining a base station installation place taking into account surrounding base station installation situations.SOLUTION: A method for determining a base station installation place is a processing method for a base station installation place determination device. It arbitrarily selects a base station installation place and a communication channel allocated to the place from a plurality of base station candidates associating a plurality of base station installation place candidates, communication channels which can be allocated to the base station installation place candidates, and sections where the communication radio waves of the communication channels reach; and determines another base station installation candidate among candidates excluding other base station candidates interfering with the communication radio wave on the selected communication channel.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a base station installation location determination apparatus, a base station installation location determination method, and a program.

  Conventionally, a train control system that prevents a collision accident between trains by dividing a track into a plurality of sections and restricting trains entering each section has been used. However, in order to control the train interval by this method, there is a problem that many ground facilities such as a track circuit, a ground signal, and an automatic train stop device are required.

  On the other hand, with the development of wireless communication technology and information processing technology in recent years, introduction of train control systems using wireless communication technology has also begun. In the case of train control by wireless communication, each train transmits its own position information to a nearby base station, and from there, the position information of each train is further transmitted to the ground device. And a ground apparatus controls a train space | interval, a course, a railroad crossing, etc. using the integrated positional information on each train. In addition, the ground device transmits information such as a speed pattern and a limit position where the head of the train must not exceed to each train via each base station, and controls the train interval and the like. In this train control system using wireless communication, it is possible to reduce many ground facilities that have been conventionally required.

  By the way, when introducing a train control system using wireless communication, communication quality of wireless communication becomes a problem. For example, when the communication quality is not sufficient, it is necessary to frequently stop the train from the viewpoint of ensuring safety, or the traveling of the train cannot be accurately controlled. For example, Patent Document 1 discloses a technique for maintaining communication quality of wireless communication. In Patent Literature 1, in a train where users are concentrated, in order to prevent a decrease in communication quality due to a rapid increase in the number of simultaneous connections from mobile terminals possessed by the users, it varies according to the number of terminals accommodated by each base station. A method is described in which a minimum number of base stations are arranged so that the communication quality with respect to the terminals in the train satisfies a desired value in consideration of the amount of interference to be performed.

Japanese Patent No. 4655836

  However, wireless communication in the train control system is not only required to maintain communication quality for the maximum number of simultaneous connections that can be assumed, but always at the location where the train communicates to ensure the safety of the train. It is to ensure sufficient communication quality.

  Accordingly, an object of the present invention is to provide a base station installation location determination apparatus, a base station installation location determination method, and a program that can solve the above-described problems.

  A first aspect of the present invention is a processing method of a base station installation location determination apparatus, a plurality of base station installation candidate locations, a communication channel that can be assigned to a base station installed in the base station installation candidate location, A plurality of base station candidates that are associated with each other, and each base station candidate has a section in which communication radio waves transmitted by the base station candidate are transmitted. A first step of selecting a station installation candidate location and a communication channel to be assigned to a base station installed at the base station installation candidate location, and determining the first base station candidate, and the base station installation candidate selected in the first step A second step of selecting a base station candidate including a combination of a location and all communication channels that can be assigned to the base station installed at the base station installation candidate location; and a communication transmitted by the first base station candidate. A third step of selecting a base station candidate other than the first base station candidate that interferes with radio waves; and the first base station from among the base station candidates excluding the base station candidates selected up to the third step Select a base station candidate that interferes with the communication radio wave transmitted by the candidate, and select a section in which the communication radio wave transmitted by the first base station candidate included in the section in which the communication radio wave defined for the selected base station candidate reaches And selecting a section selected in the fourth step from the base station candidates excluding the base station candidates selected in the first step to the third step from the base station candidates. This is a base station installation location determination method that repeats the steps from the first step with the excluded base station candidate as a new base station candidate.

  In the base station installation location determination method according to the second aspect of the present invention, the section in which the communication radio wave arrives is a communicable section indicating a section in which communication can be performed at a predetermined frame loss rate or less, and communication cannot be performed at a predetermined frame loss rate or less. And a radio wave interference section indicating a section that affects a communication radio wave transmitted by another base station, and in the third step, at least a part of the communicable section of the first base station candidate can be communicated with the base station. A base station candidate other than the first base station candidate associated with the communication channel that interferes with the communication channel selected in the first step, and at least a part of the communicable section of the first base station candidate included in the section Base station candidates other than the first base station candidates associated with the communication channel that interferes with the communication channel selected in the first step, To select as the base station candidates other than interfering the first base station candidate to the communication radio wave.

  In the base station installation location determining method according to the third aspect of the present invention, the communication radio wave reaches the communication possible section indicating a section where communication can be performed at a predetermined frame loss rate or less, and communication cannot be performed at a predetermined frame loss rate or less. In the fourth step, at least a part of the radio interference section of the first base station candidate can be communicated with the base station in the fourth step. Base station candidates with which the communication radio wave interferes with base station candidates other than the base station candidates selected up to the third step associated with the communication channel that interferes with the communication channel selected in the first step included in the section And the radio wave interference section of the first base station candidate included in the communicable section in the selected base station candidate is selected.

  In the base station installation location determining method according to the fourth aspect of the present invention, in the first step, an arbitrary base station installation candidate location and a communication channel that can be assigned to a base station installed in the base station installation candidate location. select.

  According to a fifth aspect of the present invention, when base stations are arranged based on all base station candidates selected by repeating the first step to the fourth step, all communication target positions set in advance are set. In each case, a combination of base station candidates when communication with a predetermined number of base stations can be performed without interfering with communication channels assigned to other base stations is determined as one of the base station arrangement plans. This is a base station installation location determination method.

  In the sixth aspect of the present invention, an installation cost when a base station is installed in the base station installation candidate location is set in advance in the base station installation candidate location, and is selected in each of the determined base station arrangement plans The base station installation location determining method of summing up the installation costs for all the base station installation candidate locations and selecting a base station arrangement plan when the total of the installation costs is the smallest among a plurality of base station arrangement plans It is.

  A 7th aspect of this invention is a base station installation location determination apparatus provided with the calculation part which performs the base station installation location determination method as described in the above-mentioned 1st-6th aspect.

  According to an eighth aspect of the present invention, a computer of a base station installation location determination apparatus associates a plurality of base station installation candidate locations with communication channels that can be assigned to base stations installed at the base station installation candidate locations. A plurality of base station candidates, and each base station candidate has a section in which a communication radio wave transmitted by the base station candidate reaches, and from among the plurality of base station candidates, a base station installation candidate Means for executing a first step of selecting a location and a communication channel to be assigned to a base station to be installed at the base station installation candidate location and determining it as a first base station candidate, the base station installation candidate selected in the first step Means for executing a second step of selecting a base station candidate including a combination of a location and all communication channels that can be assigned to the base station installed at the base station installation candidate location; Means for executing a third step of selecting a base station candidate other than the first base station candidate that interferes with a communication radio wave transmitted by a ground station candidate; and the base excluding the base station candidates selected up to the third step The first base station included in a section in which a communication radio wave transmitted from the first base station candidate interferes with a communication radio wave defined for the selected base station candidate is selected from station candidates. Means for executing a fourth step of selecting a section in which a communication radio wave transmitted by the candidate arrives, from the base station candidates excluding the base station candidates selected in the first step to the third step from the base station candidates; Further, a program for causing a base station candidate excluding the section selected in the fourth step as a new base station candidate to function as means for repeating the steps from the first step. That.

  According to the present invention, the location of a base station can be determined.

It is a figure which shows an example of the base station arrangement | positioning model in embodiment which concerns on this invention. It is a 1st figure explaining the problem setting of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a 2nd figure explaining the problem setting of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a 3rd figure explaining the problem setting of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a 1st figure explaining the outline of the solution algorithm of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a 2nd figure explaining the outline of the solution algorithm of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a 3rd figure explaining the outline of the solution algorithm of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is the 4th figure explaining the outline of the solution algorithm of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a 5th figure explaining the outline of the solution algorithm of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a 6th figure explaining the outline of the solution algorithm of the base station arrangement | positioning problem in embodiment which concerns on this invention. It is a flowchart of the base station installation location determination process in embodiment which concerns on this invention. It is a figure which shows an example of the result of the base station installation place determination process in embodiment which concerns on this invention. It is a block diagram which shows an example of the hardware constitutions of the base station installation location determination apparatus in embodiment which concerns on this invention.

<Embodiment>
Hereinafter, a base station installation location determination method according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram illustrating an example of a base station arrangement model in an embodiment according to the present invention.
Reference numeral 30 indicates a part of the traveling route of the train. Reference numerals 21 </ b> A to 26 </ b> A indicate installation candidate locations of base stations arranged along the travel route 30 on one side of the travel route 30. Reference numerals 21 </ b> B to 26 </ b> B indicate base station installation candidate locations that are arranged along the travel route 30 on the side facing the base station installation candidate locations 21 </ b> A to 26 </ b> A across the travel route 30. Reference numerals 1 to 6 indicate places where the train traveling on the travel route 30 performs wireless communication with the base station.
In this embodiment, a base station installation candidate location and a position (mobile station position) where the train performs wireless communication are given in advance, and an appropriate installation location is selected from these base station installation candidate locations, and the base station Consider the problem of deciding how many to install or how many. For example, in FIG. 1, it is considered that an appropriate base station installation location is selected from the base station installation candidate locations 21A to 26A and 21B to 26B so that communication is possible at all mobile station positions 1 to 6. . Appropriate selection means, for example, that the installation cost is selected to be the lowest, or that it is possible to communicate with a plurality of base stations from any mobile station position in order to prevent communication failure due to a base station failure or the like. And so on.

Hereinafter, the problem setting in the base station arrangement problem of the present embodiment will be described with reference to FIGS.
FIG. 2 is a first diagram for explaining the problem setting of the base station arrangement problem in the embodiment according to the present invention.
In FIG. 2A, the base station installation candidate location 23A is selected from the base station installation candidate locations 21A to 26A, and the base station installation candidate location 25B is selected from the base station installation candidate locations 21B to 26B. Shows the case. It is assumed that one communication channel is allocated to each of the base stations installed at the base station installation candidate locations 23A and 25B selected at this time. The communication channels to be assigned are selected so that radio wave interference does not occur as described later. If radio wave interference does not occur, the same communication channel may be assigned or different communication channels may be assigned. Hereinafter, assigning a communication channel to a base station at a certain base station candidate location may be expressed as assigning a communication channel to a certain base station candidate location.
In the case of FIG. 2A, communication channel 1 (CH1) is assigned to the base station installation candidate location 23A, and CH3 is assigned to the base station installation candidate location 25B. At this time, it is assumed that only one communication channel can be allocated to each base station installation candidate location. In addition, it is assumed that the communication channels that can be allocated to the respective base station installation candidate locations are determined in advance. For example, it is assumed that the condition that the communication channel assigned to each base station installation candidate location is any one of CH1, CH2, CH3, CH4, and CH5 is defined.

  Further, it is assumed that the base station installation cost is set in advance for each base station installation candidate location. For example, if each base station is connected to a station via a communication line, and the candidate base station installation location is near the station, the cable laying cost for the communication line is low, and a lower installation cost is set accordingly. If the station installation candidate location is far from the station, a higher installation cost is set for the base station installation candidate location because the cost for laying the cable increases. In the example of FIG. 2A, if a base station is installed in the base station installation candidate location 23A, it costs 10 million yen, and if a base station is installed in the base station installation candidate location 25B, it costs 13 million yen. It shows that it costs 23 million yen in total when installed in both. It is assumed that the installation cost of the base station is the same regardless of which communication channel is allocated to the base station installation candidate location.

  FIG. 2B shows an example in which another base station installation candidate location is selected. In the case of FIG. 2B, the base station installation candidate location 23A is selected, CH3 is allocated thereto, and the installation cost is 10 million yen. In addition, the base station installation candidate location 21B is selected, and CH2 is allocated thereto, and the installation cost is 15 million yen. In addition, the base station installation candidate place 26B is selected, and CH4 is assigned thereto, and the installation cost is 12 million yen. If a base station installation candidate location is selected as shown in FIG. 2B, a total of 37 million yen is required. Thus, in this embodiment, when a base station installation candidate location is selected, the installation cost for installing the base station is determined there.

FIG. 3 is a second diagram illustrating the problem setting of the base station arrangement problem in the embodiment according to the invention.
FIG. 3A shows a case where CH2 is assigned to the base station installation candidate location 21A, and similarly, CH1 is assigned to the base station installation candidate location 24A and CH3 is assigned to the base station installation candidate location 25B. Show. Further, when the train passes through the mobile station position 3, the wireless communication device provided in the train communicates with the base station at the base station installation candidate location 24A, and the signal transmitted from this base station is sent to the mobile station position 3. The frame loss rate when the wireless communication device of the train being received receives is 0.12%.
Similarly, FIG. 3B shows CH3 in the base station installation candidate location 22A, CH1 in the base station installation candidate location 24A, CH4 in the base station installation candidate location 26A, CH1 in the base station installation candidate location 21B, and base station installation candidate. The case where CH2 is allocated to the location 25B is shown. In addition, the frame loss rate when the train radio communication device located at the mobile station position 3 receives a signal transmitted from the base station at the base station installation candidate location 24A is 0.08%. . In the following, communication between a base station installed at a base station installation candidate location and a train radio communication device located at a mobile station location is performed between the base station at the base station installation candidate location and the mobile station location. It may be expressed as follows.

As shown in FIGS. 3 (a) and 3 (b), a radio communication apparatus for a train in which a signal transmitted from a base station at a base station installation candidate location 24A to which the same CH1 is assigned is located at a mobile station position 3 is Even in the case of reception, the frame loss rate in communication between the base station at the base station installation candidate location 24A and the mobile station position 3 varies depending on the installation environment around the base station installation candidate location 24A. The surrounding installation environment refers to the installation locations of base stations arranged around the base station installation candidate location 24A and the communication channels assigned to those base stations.
In the train control system, it is necessary to ensure sufficient communication quality so that the train can be run stably. Therefore, the base station installation candidate location must be selected in consideration of the surrounding installation environment. In the present embodiment, an allowable frame loss rate threshold is determined, and the location of the base station and the communication channel to be allocated are determined so that the frame loss rate is equal to or less than the threshold. In this embodiment, based on the surrounding base station arrangement and communication channel assignment status, if any communication channel is assigned to which base station installation candidate location, the frame loss rate of the signal transmitted from that base station is below the threshold value. It is assumed that information about whether or not it can be suppressed to has been given by simulation or the like, and that information is given in advance.

FIG. 4 is a third diagram for explaining the problem setting of the base station arrangement problem in the embodiment according to the invention.
FIG. 4A shows that CH1 is assigned to the base station installation candidate location 21A, CH4 is assigned to the base station installation candidate location 22A, CH2 is assigned to the base station installation candidate location 25A, and CH4 is assigned to the base station installation candidate location 26A. Shows the case. Reference numerals 41 </ b> A to 41 </ b> D indicate a range in which communication is possible with a base station installed at each base station installation candidate location within a threshold of an acceptable frame loss rate. If the base station at the base station installation candidate location 21A to which CH1 is assigned is expressed as a base station (21A, CH1), for example, at the mobile station position 1, the base station (21A, CH1), base station (22A, CH4) ). Similarly, mobile station position 2 and mobile station position 3 can communicate with base stations (21A, CH1) and base stations (22A, CH4). In mobile station position 4, communication is possible with the base station (22A, CH4) and the base station (25A, CH2). Further, at the mobile station position 5 and the mobile station position 6, communication is possible with the base station (25A, CH2) and the base station (26A, CH4). In the example of FIG. 4 (a), communication with two base stations is possible at all mobile station positions 1 to 6, respectively.

  On the other hand, in the case of FIG. 4B, the mobile station positions 1, 2, and 3 can communicate with the base station (21A, CH1) and the base station (22A, CH3). In mobile station position 4, communication is possible with the base station (22A, CH3) and the base station (25A, CH2). However, at the mobile station positions 5 and 6, communication is possible only with the base station (25A, CH2). In a train control system, it is important to always be able to communicate with a base station from all mobile station positions even if some base station fails in terms of stability. Therefore, in the present embodiment, it is possible to arrange base stations so as to be able to communicate with a plurality of (for example, two) base stations from all mobile station positions.

  The above is the problem setting in the base station arrangement problem of this embodiment. An object of the present embodiment is to obtain a combination that minimizes the installation cost among combinations of base station arrangement and communication channel assignment that satisfy these conditions.

Next, a method for determining the above combination will be described with reference to FIGS. In addition, the algorithm demonstrated below shall determine said combination, when the computer with which a base station installation location determination apparatus is provided executes the program which described the said algorithm. A function provided when a CPU (Central Processing Unit) provided in the base station installation location determining apparatus executes the program is referred to as a calculation unit.
FIG. 5 is a first diagram for explaining the outline of the algorithm for solving the base station arrangement problem in the embodiment according to the present invention.
In the following, a method for determining the arrangement will be described by taking as an example the case where the base station with which the train radio communication apparatus located at the mobile station positions 1 to 10 communicates is selected from the base station installation candidate locations 21A to 25A and the arrangement is determined. The algorithm for solving is described. In addition, it is assumed that the communication channel assigned to each base station installation candidate location is any one of CH1, CH2, CH3, CH4, and CH5. Communication channels that interfere with CH1 are CH1 and CH2, communication channels that interfere with CH2 are CH1, CH2, and CH3. Communication channels that interfere with CH3 are CH2, CH3, and CH4, and communication that interferes with CH4. Channels are CH3, CH4, and CH5, and communication channels that interfere with CH5 are CH4 and CH5.

  Reference numeral 31A indicates a section (communication available section) in which communication is possible with a frame loss rate equal to or less than the threshold e when a communication channel in the base station installation candidate location 21A is assigned. This communicable section is a section in which communication of quality that can be used for train control is possible between the wireless communication device provided in the train and the base station when the train is present at each mobile station position. Further, reference numeral 31B indicates a section (a radio wave interference section) where a radio wave arrives although the frame loss rate exceeds the threshold e when a communication channel in the base station installation candidate location 21A is assigned. This radio wave interference section indicates a section in which communication of quality that can be used for train control cannot be performed, but may interfere with radio waves from other base stations. Similarly, reference numeral 32A indicates a communicable section when a communication channel in the base station installation candidate location 22A is allocated, and reference numeral 32B indicates a radio wave interference section at that time. Reference numeral 33A indicates a communicable section when a communication channel in the base station installation candidate location 23A is allocated, and reference numeral 33B indicates a radio wave interference section at that time. Reference numeral 34A indicates a communicable section when a communication channel in the base station installation candidate location 24A is allocated, and reference numeral 34B indicates a radio wave interference section at that time. Reference numeral 35A indicates a communicable section when a communication channel in the base station installation candidate location 25A is allocated, and reference numeral 35B indicates a radio wave interference section at that time.

FIG. 6 is a second diagram for explaining the outline of the algorithm for solving the base station arrangement problem in the embodiment according to the invention.
FIG. 6 illustrates a base station candidate in which a plurality of base station installation candidate locations and communication channels that can be assigned to the base station installation candidate locations are associated with each other, and a section in which communication radio waves defined for each base station candidate reach. FIG. The rows in the table of FIG. 6 indicate base station installation candidate locations, and the columns indicate assignable communication channels. Also, the numerical values described in the upper part of each column (cell) are the mobile station positions included in the communicable section, and the numerical values described in the lower part are the mobile station positions included in the radio wave interference section. For example, in the first row and the first column, when CH1 is assigned to the base station installation candidate location 21A, the mobile station positions that can communicate with the frame loss rate equal to or less than the threshold e are 1, 2, 3, and 4. Although the rate exceeds the threshold value e, the mobile station position where the radio wave arrives is 5. Even if CH1 is allocated to the base station installation candidate location 21A, radio waves do not reach the mobile stations 6, 7, 8, 9, and 10.
In addition, the number written in the lower parentheses in the 0th column base station installation candidate location is the installation cost. For example, the installation cost of the base station installation candidate location 21A is 10 million yen, and the installation cost of the base station installation candidate location 22A is 8 million yen.
The above is information given as a precondition for the algorithm for solving the base station arrangement problem. It is assumed that these pieces of information are stored in advance in the base station installation location determining device or given from the outside when executing a program describing a solution algorithm.

Next, an outline of the algorithm will be described with reference to FIGS.
FIG. 7 is a third diagram for explaining the outline of the algorithm for solving the base station arrangement problem in the embodiment according to the invention.
The first and second steps will be described with reference to FIG. First, one combination in which the calculation unit is randomly selected from all combinations of the base station installation candidate location and the communication channel shown in FIG. As an example, assume that a base station candidate consisting of a combination of the base station installation candidate location 22A and CH3 is selected. In the figure, the selected base station (22A, CH3) is indicated by being surrounded by a thick frame, and is excluded from the base station installation candidate locations because of interference of radio waves with other base stations (i , K) is expressed by shaded cells. Subsequently, since it is a problem setting that only one communication channel can be assigned to one base station, among the base station candidates, the base station (22A, CH1), base station (22A, CH2), base station (22A, CH4) ) And the base station (22A, CH5) are set as exclusion targets. FIG. 7B is a diagram illustrating that the calculation unit selects the base station (22A, CH3) (first step), and sets communication channels other than CH3 to be excluded (second step).

FIG. 8 is a fourth diagram for explaining the outline of the algorithm for solving the base station arrangement problem in the embodiment according to the invention.
The third step will be described with reference to FIG. The communicable sections of the base station (22A, CH3) are mobile station positions 1, 2, 3, 4, and 5. Therefore, base stations (i, k) that transmit communication radio waves that interfere with communication radio waves transmitted by the base station (22A, CH3) are excluded from base station candidates. This is because when such an exclusion target base station (i, k) is installed, communication radio waves of the base station (22A, CH3) are interfered and communication quality deteriorates. In this case, the excluded base station (i, k) has at least one of 1, 2, 3, 4, 5 in the communicable section or radio wave interference section of the base station itself, and CH3 Is a base station (i, k) to which a communication channel that interferes with is assigned. When any one of 1, 2, 3, 4, 5 is described in the upper or lower part of the cell and the base station candidates assigned with CH2, CH3, and CH4 that interfere with CH3 are listed, the base station ( 21A, CH2), base station (21A, CH3), base station (21A, CH4), base station (22A, CH2), base station (22A, CH3), base station (22A, CH4), base station (23A, CH2), base station (23A, CH3), base station (23A, CH4), base station (24A, CH2), base station (24A, CH3), base station (24A, CH4). The calculation unit sets these to be unselectable.

The fourth step will be described with reference to FIG. In this fourth step, a communication channel that interferes with CH3 is allocated among the base stations that include the mobile station position included in the radio wave interference section of the base station (22A, CH3) in the communicable section of the base station itself. Select the base station (i, k), select the mobile station position (“6”) included in the radio wave interference section of the base station (22A, CH3) from the communicable section of the base station (i, k), This is excluded. This is because even if CH2, CH3, and CH4 that interfere with CH3 are assigned and the base station (i, k) that includes the radio wave interference section of the base station (22A, CH3) in the communicable section of the base station is selected, In the radio wave interference section of the base station (22A, CH3), the selected communication radio wave from the base station (i, k) is interfered with the communication radio wave transmitted from the base station (22A, CH3), and the communication quality is reduced. This is because it will deteriorate. The above-mentioned third step was intended to exclude the base stations (i, k) that interfere with the communication radio waves of the selected base station (22A, CH3), whereas this fourth step The purpose is to prevent interference with communication radio waves of other base stations (i, k) due to arrival of radio waves of the stations (22A, CH3).
As shown in the third and fourth steps, in the present embodiment, the base station arrangement is determined so as not to cause interference with each other in consideration of radio wave interference according to the installation status of the neighboring base stations.
Reference numerals 40A to 40C are mobile station positions excluded in the fourth step.

  In the next step, base station candidates excluding the plurality of base stations (i, k) selected as the exclusion targets in the first to third steps are selected and set as new base station candidates. In FIG. 8B, the base station (21A, CH1), base station (21A, CH5), base station (23A, CH1), base station (23A, CH5), base station (24A, CH1), base station ( 24A, CH5), base station (25A, CH1), base station (25A, CH2), base station (25A, CH3), base station (25A, CH4), base station (25A, CH5) are new base station candidates It is. However, for the base station (25A, CH2), base station (25A, CH3), and base station (25A, CH4) selected in the fourth step, the base station (22A, CH3) is determined from the mobile station position included in the communicable section. ) Mobile station position “6” included in the radio wave interference section is excluded.

FIG. 9 is a fifth diagram for explaining the outline of the algorithm for solving the base station arrangement problem in the embodiment according to the invention.
FIG. 9A shows a result of performing the first to fourth steps again for a new base station candidate set after the fourth step in FIG. 8B. First, the base station (21A, CH1) is the second base station candidate selected randomly by the calculation unit. The base station (21A, CH5) is a base station (i, k) selected because only one communication channel is assigned to one base station. The above is the first and second steps. The base station (23A, CH1) and the base station (24A, CH1) select one of the communicable sections (1, 2, 3, 4) of the base station (21A, CH1) newly selected in the third step. This is a base station (i, k) that has a communicable section or a radio wave interference section of the base station. There is no base station (i, k) selected by the fourth step. After the fourth step, the base station installation location determination device determines that the base station (25A, CH1), the base station (23A, CH5), the base station (24A, CH5), the base station (25A, CH5), and the communicable section Base stations (25A, CH2), base stations (25A, CH3), and base stations (25A, CH4) from which “6” is excluded are set as new base station candidates.

FIG. 9B shows the result of performing the first to fourth steps again for the new base station candidate set in FIG. 9A. First, the base station (24A, CH5) is the third base station candidate that is randomly selected by the calculation unit. The base station (23A, CH5), the base station (25A, CH4), and the base station (25A, CH5) are base stations (i, k) set to be unselectable in the third step.
The process from the first step is further repeated for the remaining base station candidates. At this time, the base station (25A, CH1) is the fourth base station candidate randomly selected by the calculation unit. Here, since it becomes possible to communicate with two base stations from all mobile station positions, the processing ends.

FIG. 10 is a sixth diagram for explaining the outline of the algorithm for solving the base station arrangement problem in the embodiment according to the invention.
FIG. 10 shows that each of the mobile station positions 1 to 10 can communicate with two base stations. For example, the mobile station position 1 can communicate with the base station (21A, CH1) and the base station (22A, CH3). In addition, the mobile station position 5 can communicate with the base station (22A, CH3) and the base station (24A, CH5). The same applies to other mobile station positions.
Moreover, it turns out that the installation cost at this time is 10 million + 8 million + 14 million + 18 million = 50 million yen.

Next, the algorithm will be described in detail.
<Problem settings>
Base station installation location candidates and mobile station positions are given in advance. Also, the communication channels that can be assigned to each base station are determined, and only one of them is assigned. Also, the frame loss rate varies depending on the surrounding base station installation situation. Each mobile station location must be able to communicate with at least u base stations. Here, u is an input parameter.

<Formulation>
M = {1, 2,..., | M |}, a set of base station installation candidate locations
N = {1, 2,..., | N |},
A set of communication channels that can be used in each base station is P = {1, 2,..., | P |}.
C _i , the installation cost when installing a base station at a base station installation candidate location i∈M,
Let e be the threshold of the frame loss rate at each mobile station position.
A base station of a communication channel kεP to be installed at a base station installation candidate location iεM is a base station (i, k)
Communication between the base station (i, k) and the mobile station position j∈N is communication (i, j, k),
If there is no influence of radio wave interference from the base station (i, k) from other base stations, a set of mobile station positions that can communicate with the frame loss rate e or less is N _ik .
A directed graph composed of a node set V = M∪N and an arc set A = {(i, j, k) εM × N × P | jεN _ik , iεM, kεP} is represented by G = (V , A).
The communication (i, j, k) may be any one of the base station (i ₁ , k ₁ ), the base station (i ₂ , k ₂ )..., The base station (i _r , k _r ). If it is installed, the frame loss rate exceeds the threshold value e. At this time, a set of these base stations {base station (i ₁ , k ₁ ), base station (i ₂ , k ₂ ). Station (i _r , k _r )} is denoted by B _ijk .
A variable x _{ijk is assigned} to the communication (i, j, k) and a variable y _ik is _{assigned to the} base station (i, k).

Of the base station arrangements that allow communication at an allowable frame loss rate or less at each mobile station position, the problem of obtaining the base station arrangement that minimizes the installation cost is formulated into the following 0-1 integer programming problem. The However, u is a positive integer.
Minimize

  Subject to

x _ijk ≦ y _ik , (i, j, k) ∈ A (3)

x _ijk + y _{i * k *} ≦ 1, (i ^* , j ^* ) ∈B _ijk ,
(I, j, k) ∈ A (5)

x _ijk ∈ {0, 1}, (i, j, k) ∈ A (6)
y _ik ∈ {0, 1}, i ∈ M, k ∈ P (7)

  In the above formulation, Equation (1) is an objective function, which indicates that the purpose is to minimize the base station installation cost. In addition, Expressions (2) to (5) are constraint conditions. Expression (2) is a condition for guaranteeing that each mobile station position can communicate with u or more base stations. Expression (3) is a condition for guaranteeing that a necessary base station is installed. Equation (4) is a condition that guarantees that each base station is not assigned more than one communication channel. Expression (5) is a condition for guaranteeing that communication with a frame loss rate exceeding the threshold value e due to radio wave interference is not used. Expressions (6) and (7) are 0-1 conditions for the decision variable.

Next, a solution algorithm for this problem will be described.
Here, a set of mobile station positions where the frame loss rate of the signal transmitted from the base station (i, k) exceeds the threshold value e even if there is no influence of radio wave interference from other base stations.

Also, let P _k be a set of communication channels in which radio waves may interfere with the communication channel _k . Further, it is assumed that W _ik = N _ik ∪N ^- _ik . _{Incidentally, N ik} is a set of upper values of each cell in Figures 7-9 for ^{example, N} _{- ik} is the set of lower value.

Input value in this _{algorithm, M, N, P, c} i, u, N ik, N - ik, P k, a _{B ijk.} The output value is

It is.

Step 0: A ^ = φ, B ^ = φ, Z ^ = ∞. Note that φ is an empty set.
Step 1:

Let B = M × P. In addition, n _j = 0 and j∈ N.
The above is initialization.

Step 2: Obtain an arbitrary (i ^* , k ^* ) εB and update it as follows.
B ⁻ : = B ⁻ ∪ {(i ^* , k ^* )}
Z ⁻ : = Z ⁻ + ci _*
In this step, any one of the base stations from among the locatable base station (i ^{*, k *)} is selected, the base station the base station set B ^- is added to.

Step 3: In Search of ^{A *} in the following ^{formula, A -: = A - ∪A} * to update.
A ^* = {(i, j, k) ∈A | i = i ^* , j∈N _{i * k *} , k = k ^* }
In this step, the base station (i ^{*, k *)} and seeking communication frame loss rate is equal to or less than the threshold value e, they A ^- add to.

Step 4: Update _nj as follows.
n _j : = n _j + 1, j ∈ N _{i * k *}
If n _j : = u and j ∈ N, the process proceeds to step 9.
In this step, the number of base stations that can communicate at each mobile station position is confirmed. As a result, if the number of base stations that can communicate at all mobile station positions is greater than or equal to u, a possible problem solution has been obtained.

Step 5: Find the next B ′, B ″, B ″ ′.
B ′ = {(i, k) ∈B | i = i ^* , k∈P}
B ″ = {(i, k) ∈B | k∈P _{k *} , W _ik N _{i * k *} ≠ φ}
B ′ ″ = {(i, k) ∈B | k∈P _{k *} ,
N _ik ∩N ⁻ _{i * k *} ≠ φ}
When the base station (i ^* , k ^* ) is selected in step 2, no other base station can be installed at the base station installation candidate location i ^* . In this step, such a base station set B ′ is obtained (second step). In addition, when the base station (i ^* , k ^* ) is installed, the mobile station position included in _{Ni * k *} and the communication quality between the base station (i ^* , k ^* ) are newly added. The base station to be installed must be selected. That is, a new base station is arranged so that signals from the base station to which the communication channel k ^* and a communication channel that may cause radio wave interference are assigned do not reach each mobile station position included in _{Ni * k *.} Must be installed. In this step, a base station set B ″ that may cause such radio wave interference is obtained (third step). The signal transmitted from the base station (i ^* , k ^* ) can be received at each mobile station position included in N ^- _{i * k *} although the frame loss rate exceeds the threshold value e. Therefore, in this step, a set B ′ ″ of base stations including such mobile station positions is obtained.

Step 6: Update B and N _ik as follows:
B: = B- (B′∪B ″)
N _ik : = N _ik −N ⁻ _{i * k *} , (i, k) ∈B ′ ″
In this step, B ′ is excluded from B which is a set of installable base stations. In this step, B ″ is further excluded from B, which is a set of base stations that can be installed. Also, for B ′ ″, N _ik , (i, k) εB ′ ″ to N ⁻ _{i *} so as not to cause radio wave interference with the signal transmitted from the base station (i ^* , k ^* ) _. Select _{k *} (4th step) and delete it.

Step 7: Update N _ik as follows.
N _ik : = N _ik − {j∈N | n _j = u}, (i, k) ∈B
In this step, N _ik , (i, k) εB is updated as the base station (i ^* , k ^* ) is installed.

Step 8: B is further updated as follows, and the processing from Step 2 is repeated. At this time, if B ≠ φ, the process proceeds to step 10.
B: = B − {(i, k) ∈B | N _ik = φ}
In this step, the base station with N _ik = φ as a result of updating B in Step 6 is excluded from the subsequent base station selection candidates.

Step 9: Z ^> Z ^- if
^{A ^: = A -, B} ^: = B -, Z ^ = Z - to update.
Z ^ is the minimum installation cost in the conventional base station arrangement plan. The provisional solution will be updated if the installation cost for the proposed base station arrangement is less than this.

Step 10: If the end condition is not satisfied, return to Step 1. Otherwise, go to step 11. The termination condition is a processing time limit, an upper limit value of the number of loops, or the like. This termination condition is assumed to be given in advance.
Step 11: Output A ^, B ^, Z ^ and finish.

There is no guarantee that a possible solution is always obtained with this algorithm. For example, if none of the base station arrangement plans satisfying n _j : = u and j ∈ N can be obtained in step 4 at the end of the algorithm, a solution satisfying the constraint condition of Expression (2) cannot be obtained. That's right. On the other hand, if even one base station arrangement plan that satisfies the condition in step 4 is obtained, a possible solution is obtained. At this time, x _ijk and y _ik in the formulation are determined by the following equations from A ^ and B ^ output by the algorithm.

Further, the value of the expression (1) that is an objective function is Z ^.

  According to the present embodiment, it is possible to simultaneously determine the number of base stations to be installed, the location of the base stations, and the communication channels to be allocated in consideration of changes in the communication environment due to the surrounding communication channel usage conditions.

FIG. 11 is a flowchart of base station installation location determination processing according to the embodiment of the present invention.
A process in which the base station installation location determining apparatus according to the present embodiment executes a program describing the above-described algorithm will be described with reference to FIG.
As a premise, a data table in which the base station (i, k) and its communicable section and radio wave interference section illustrated in FIG. 6 are stored in advance in the storage unit provided in the base station installation location determination device. To do. This data table is referred to as a base station candidate set table. In addition, in the data of each cell of the base station candidate set table, in addition to the information on the mobile station position in the communicable section and the mobile station position in the radio wave interference section illustrated in FIG. It is assumed that a selection flag is provided, and “0” representing non-selection is set as an initial value. Further, it is assumed that installation cost information is stored for each row of the base station candidate set table. In the description, FIG. 6 is used as an example. That is, the communication channels are CH1 to 5, the base station installation candidate locations are 21A to 25A, and the mobile station positions are 1 to 10.
First, the calculation unit randomly selects a base station (i ^* , k ^* ) from the base station candidate set table using a predetermined method (step S11). For example, a random number may be generated in the range of 1 to 5 for each row and column, and the base station (i, k) associated with the random number may be selected. Calculation unit selected base station (i ^{*, k *)} to select flags, the base station (i ^{*, k *)} is set to "1" which means that it has been selected as an installation candidate.
Next, the calculation unit selects all base station candidate data in the row of the selected base station (i ^* , k ^* ), and sets “2”, which means a selection exclusion target, for each of the selection flags. That is, the base stations (i, k) are selected as targets for which the base station cannot be installed (step S12). For example, when the base station (2, 3) is selected in step S11, the calculation unit sets the selection flag of the base station (2, k) (k = 1 to 5) to 2. This corresponds to the fact that at the selected base station installation location (i = 2), only CH3 can be used and other communication channels cannot be used.

Next, the calculation unit reads the mobile station position of the communicable section of the base station (i ^* , k ^* ) from the base station candidate set table, and the read mobile station position is the communicable section or radio wave interference section of the base station. Are searched for, and “2” is set in the selection flag for each of the found base stations (i, k). That is, the calculation unit selects another base station candidate that interferes with the communicable section of the base station (i ^* , k ^* ) (step S13).
Next, the calculation unit reads the mobile station position in the radio wave interference section of the base station (i ^* , k ^* ) from the base station candidate set table, and has the read mobile station position in the communicable section of the base station. (I, k) is selected (step S14).
Next, the calculation unit updates the selection flag of the base station (i, k) selected in steps S12 to S13. In addition, the calculation unit can communicate with each of the base stations (i, k) selected in step S14 by deleting the mobile station position in the radio wave interference section of the base station (i ^* , k ^* ) from the communicable section. The section is updated (step S15). A new base station candidate set table in which a plurality of base station installation candidate locations updated in step S15, communication channels that can be assigned to the base station installation candidate locations, communicable sections, and radio wave interference sections are associated with each other Station candidate.

Next, the calculation unit makes an end determination (step S16). The calculation unit confirms the mobile station positions included in the communicable section of the cell in which “1” is set in the selection flag, and all mobile station positions are u (for example, 2) base stations (i, k). If it is included in the communicable section, it is determined to end. Or a calculation part confirms the selection flag of all the cells of a base station candidate set table, and when the value becomes "1" or "2", it determines with complete | finishing. When all mobile station positions are included in a communicable section of a predetermined number of base stations (i, k), one base station set to be obtained is obtained. If this is not the case, a solution could not be obtained in this series of processing. In this embodiment, a combination of each base station installation location candidate and a communication channel is selected at random. This is to prevent loss of the diversity of solutions by providing regularity and selecting only the base station installation candidate locations to obtain similar solutions. Therefore, in this embodiment, there are cases where a solution cannot always be obtained. However, it is possible to perform more appropriate base station arrangement from a large number of arrangement patterns by repeatedly performing calculations.
When the determination result is finished (step S16: Yes), the calculation unit reads the installation cost of the base station (i, k) in which “1” is set in the selection flag from the base station candidate set table and sums it up (step S17). Then, the calculation unit outputs the installation cost totaled with the information of the base station (i, k) in which “1” is set in the selection flag, and ends the processing flow. When the determination result is not complete (step S16: No), the calculation unit repeats the processing from step S11.

Through the above-described steps S11 to S17, one base station installation candidate location determination process is completed, and one base station arrangement plan is obtained. The calculation unit obtains the combination of the obtained mobile station position, the base station installation candidate location and the communication channel (A ^: communication set), the base station installation candidate location, the communication channel (B ^: base station set), and the installation cost (Z ^) Is stored in the storage unit.
The base station installation location determining apparatus repeats steps S11 to S17 described above, for example, a predetermined number of times, and selects and outputs a communication set, a base station set, and an installation cost when the installation cost is the lowest.

FIG. 12 is a diagram illustrating an example of a result of the base station installation location determination process in the embodiment according to the invention.
The table of FIG. 12 shows the results when the above-described steps S11 to S17 are executed 1000 times under certain conditions (results obtained by solving five instances of the same problem size and different parameter settings, and obtaining possible instances. Average value of each value obtained). The number of communication channels (| P |) that can be used in each base station is 4, 6, 8, and 10, and the number (u) of base stations that must communicate at a frame loss rate e or less from each mobile station position is 1 or The calculation was performed as 2. The first row of this table is the calculation result when | P | = 4 and u = 1. The value in the “number of possible solutions” column on the first line indicates that the number of instances for which possible solutions could be obtained when steps S11 to S15 were executed 1000 times was five. In addition, the value in the “number of base station installations” column on the first line indicates that the average installation cost in the instance where a possible solution was obtained was 2903.0 million yen, and the value in the “time” column was It shows that the average time required for 1000 iterations in the instance where a possible solution was obtained was 14.2 seconds.
From this table, for example, in the case of u = 1, it can be confirmed that the number of usable communication channels does not greatly affect the base station installation cost. Further, when u = 2, it can be confirmed that the base station installation cost can be reduced by increasing the number of usable communication channels from 6 to 8. This is so that a base station installation candidate location with a low installation cost that could not be selected because the number of communication channels is insufficient when P = 6 can be selected by increasing the number of communication channels to 8. It is thought that it became.
In addition, when | P | = 4 and u = 2, “-” is described in the “number of installed base stations” and “installation cost” columns. It means that it was not found.
According to the present embodiment, the base station arrangement that minimizes the installation cost can be determined after comparing the tendency of the installation cost under various conditions.

FIG. 13: is a block diagram which shows an example of the hardware constitutions of the base station installation location determination apparatus in embodiment which concerns on this invention.
The code | symbol 100 of FIG. 13 has shown the base station installation location determination apparatus. As shown in FIG. 13, the base station installation location determining apparatus 100 includes a CPU 101, a memory 102 such as a ROM and a RAM, a storage unit 103 such as a hard disk, and an input / output unit 104 such as a keyboard and a display. Realized. These members are connected to each other through, for example, a bus. The CPU 101 implements various functions by executing programs stored in the storage unit 103. For example, the above described calculation unit is realized by executing a program describing the sea part algorithm of the present embodiment. The storage unit 103 stores, for example, programs used for base station location determination processing, various parameters, information on communicable sections and radio wave interference sections, and various processing results.

  Each process in the base station installation location determining apparatus 100 described above is stored in a computer-readable recording medium in the form of a program, and the computer of the base station installation location determining apparatus 100 reads and executes this program. Thus, the above processing is performed. 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.
Moreover, the base station installation location determining apparatus 100 may be configured by a single computer, or may be configured by a plurality of computers connected so as to be communicable.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention. The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. The mobile station position is an example of a communication target position. The base stations (22A, CH3), base stations (21A, CH1), base stations (24A, CH5), and base stations (25A, CH1) that are selected randomly by the calculation unit are examples of first base station candidates. is there.

1-10: Mobile station position, 21A-26A, 21B-26B ... Base station installation candidate location, 30 ... Travel route, 31A-35A ... Communication possible section, 31B-35B ... Radio wave Interference section, 100 ... base station installation location determination device

Claims (8)

A processing method for a base station installation location determination device, comprising:
A plurality of base station candidates in which a plurality of base station installation candidate locations and communication channels that can be assigned to the base stations installed in the base station installation candidate locations are associated with each other. A section in which a communication radio wave transmitted by a base station candidate reaches is determined, and among the plurality of base station candidates, a base station installation candidate location, a communication channel assigned to a base station installed at the base station installation candidate location, and A first step of selecting and determining as a first base station candidate;
A second step of selecting a base station candidate including a combination of the base station installation candidate location selected in the first step and all communication channels that can be allocated to the base station installed in the base station installation candidate location;
A third step of selecting a base station candidate other than the first base station candidate that interferes with a communication radio wave transmitted by the first base station candidate;
A base station candidate that interferes with a communication radio wave transmitted by the first base station candidate is selected from the base station candidates excluding the base station candidate selected up to the third step, and the selected base station candidate is defined. A fourth step of selecting a section in which a communication radio wave transmitted by the first base station candidate included in a section in which the received communication radio wave arrives;
Have
From the base station candidates obtained by removing the base station candidates selected in the first step to the third step from the base station candidates, the base station candidates excluding the section selected in the fourth step are added as new base station candidates. Repeating the steps from the first step as a base station installation location determination method. The section in which the communication radio wave arrives includes a communicable section indicating a section where communication can be performed at a predetermined frame loss rate or less, and a section which cannot be communicated at a predetermined frame loss rate or less and which affects communication radio waves transmitted by other base stations. Including the radio wave interference section shown,
In the third step,
Including at least part of the communicable section of the first base station candidate in the communicable section of the own base station,
A base station candidate other than the first base station candidate associated with a communication channel that interferes with the communication channel selected in the first step;
The first base station candidate associated with the communication channel that interferes with the communication channel selected in the first step, including at least a part of the communicable section of the first base station candidate in the radio wave interference section of the base station. With other base station candidates,
The base station installation location determination method according to claim 1, wherein base station candidates other than the first base station candidate that interferes with the communication radio wave are selected. The section in which the communication radio wave arrives includes a communicable section indicating a section where communication can be performed at a predetermined frame loss rate or less, and a section which cannot be communicated at a predetermined frame loss rate or less and which affects communication radio waves transmitted by other base stations. Including the radio wave interference section shown,
In the fourth step,
Including at least a part of the radio interference section of the first base station candidate in the communicable section of the base station,
While selecting a base station candidate other than the base station candidate selected up to the third step associated with the communication channel that interferes with the communication channel selected in the first step as a base station candidate that interferes with the communication radio wave The base station installation location determination method according to claim 1 or 2, wherein a radio wave interference section of the first base station candidate included in the communicable section in the selected base station candidate is selected. The said 1st step WHEREIN: Arbitrary base station installation candidate places and the communication channel which can be allocated to the base station installed in the base station installation candidate place are selected. Base station installation location determination method. When base stations are arranged based on all base station candidates selected by repeating the first step to the fourth step, assignment is made to other base stations at all preset communication target positions. The combination of base station candidates when communication with a predetermined number of base stations can be performed without interfering with a designated communication channel is determined as one of the base station arrangement plans. The base station installation location determination method according to claim 1. The installation cost when a base station is installed in the base station installation candidate location is set in advance in the base station installation candidate location,
Summing up the installation costs for all base station installation candidate locations selected in each of the determined base station arrangement plans,
The base station installation location determination method according to claim 5, further comprising: selecting a base station arrangement plan when the total of the installation costs is the smallest among a plurality of base station arrangement plans. The calculation part which performs the base station installation place determination method of any one of Claims 1-6,
A base station installation location determination device comprising: Computer of the base station installation location determination device,
A plurality of base station candidates in which a plurality of base station installation candidate locations and communication channels that can be assigned to the base stations installed in the base station installation candidate locations are associated with each other. A section in which a communication radio wave transmitted by a base station candidate reaches is determined, and among the plurality of base station candidates, a base station installation candidate location, a communication channel assigned to a base station installed at the base station installation candidate location, and Means for performing a first step of selecting and determining a first base station candidate;
A second step of selecting a base station candidate including a combination of the base station installation candidate location selected in the first step and all communication channels that can be assigned to the base station installed in the base station installation candidate location is executed. means,
Means for executing a third step of selecting a base station candidate other than the first base station candidate that interferes with a communication radio wave transmitted by the first base station candidate;
A base station candidate that interferes with a communication radio wave transmitted by the first base station candidate is selected from the base station candidates excluding the base station candidate selected up to the third step, and the selected base station candidate is defined. Means for executing a fourth step of selecting a section in which a communication radio wave transmitted by the first base station candidate included in a section in which the received communication radio wave arrives;
From the base station candidates obtained by removing the base station candidates selected in the first step to the third step from the base station candidates, the base station candidates excluding the section selected in the fourth step are added as new base station candidates. Means for repeating the steps from the first step as
Program to function as.

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