Station placement design device, station placement design method, and program

Abstract

To shorten a calculation processing time required for wireless station design.SOLUTION: A station placement design device includes an index value calculation unit configured to calculate, for each of the base station candidates in a space in which a plurality of unaccommodated terminals and a plurality of base station candidates are arranged, an index value based on the number of unaccommodated terminals that can be accommodated when the base station is arranged at that base station candidate, and a base station placement selection unit configured to distribute, for each of the base station candidates, the points of the base station candidate to one or more other base station candidates that have a predetermined positional relationship with the base station candidate and have higher index values than the base station candidate, select some of the base station candidates with the highest total sums of values distributed from the other base station candidates as placement locations for the base station, and accommodate the unaccommodated terminals that can be accommodated by the some of the base station candidates.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a station placement design device, a station placement design method, and a program. [Background technology]

[0002] Since there are limits to the range of radio waves from a wireless base station and the number of terminals that a single wireless base station can accommodate, if there are not enough wireless base stations installed, the area coverage and terminal accommodation will be insufficient.On the other hand, if there are too many wireless base stations installed, the cost of the base station equipment itself, as well as installation and operation costs, will increase, resulting in inefficiency.

[0003] In order to place a necessary and sufficient number of wireless base stations in appropriate locations, wireless station design is performed to determine base station placement (installation locations and antenna directions). In wireless station design, after setting base station placement candidates, service area simulations have been proposed, such as estimation using empirical formulas (Non-Patent Document 1) and methods such as ray tracing (Non-Patent Document 2), and methods using a greedy method have been proposed as methods for placing base stations from base station placement candidates after simulating the service area (Non-Patent Document 3). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "Mobile Communication Station Design", NTT DoCoMo Technical Journal vol.2 no.4, [online], Internet <https: / / www.nttdocomo.co.jp / binary / pdf / corporate / technology / rd / technical_journal / bn / vol2_4 / vol2_4_035jp.pdf> [Non-patent document 2] "Ray Tracing Method Using Genetic Algorithm for Radio Wave Propagation Estimation", NTT DoCoMo Technical Journal vol.15 no.3, [online], Internet <https: / / www.nttdocomo.co.jp / binary / pdf / corporate / technology / rd / technical_journal / bn / vol15_3 / vol15_3_020jp.pdf> [Non-patent document 3] Toshiro Nakahira, Daisuke Murayama, Satoshi Takatani, Kenichi Kawamura, Takatsugu Moriyama, "Multi-Radio Area Design Method Based on Communication Capacity and Base Station Cost," IEICE Techniques, IEICE General Conference, B-5-97, Mar. 2022 [Non-patent document 4] J.-X. Zhang, D.-B. Chen, Q. Dong, and Z.-D. Zhao, "Identifying a set of influential spreaders in complex networks", Scientific Reports 6, pp. 1-9, June 2016 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology described in Non-Patent Document 3, a base station that can accommodate the maximum number of terminals per base station cost is selected from among base station placement candidates, and the base station is placed one by one, so the process must be repeated as many times as the number of base stations to be installed. Therefore, in an environment with a large number of base station placement candidates and evaluation points (terminals), there is a problem that the calculation time increases.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to shorten the calculation processing time required for designing a wireless station. [Means for solving the problem]

[0007] In order to solve the above problem, the station placement design device has an index value calculation unit configured to calculate, for each base station candidate in a space in which a plurality of unaccommodated terminals and a plurality of base station candidates are placed, an index value based on the number of unaccommodated terminals that can be accommodated when the base station is placed at that base station candidate; and a base station placement selection unit configured to distribute, for each of the base station candidates, the points of the base station candidate to one or more other base station candidates that have a predetermined positional relationship with the base station candidate and have higher index values than the base station candidate, select some of the base station candidates with the highest total sums of values distributed from the other base station candidates as placement locations for the base station, and accommodate the unaccommodated terminals that can be accommodated by the some of the base station candidates. [Effects of the Invention]

[0008] The calculation processing time required for wireless station design can be shortened. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a hardware configuration of a station design device 10 according to an embodiment of the present invention. [Figure 2] 1 is a diagram illustrating an example of a functional configuration of a station design device 10 according to an embodiment of the present invention. [Figure 3] 10 is a flowchart illustrating an example of a processing procedure executed by the station design device 10. [Figure 4] FIG. 10 is a diagram illustrating an example of the arrangement of base station candidates and terminals. [Figure 5] FIG. 2 is a diagram illustrating an example of a network graph G. [Figure 6] FIG. 10 is a diagram for explaining estimation of a received power value. [Figure 7] 10 is a flowchart illustrating an example of a processing procedure of a voting process. [Figure 8] FIG. 10 is a diagram illustrating an example of a result of tallying scores for each base station candidate. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this embodiment, the station location design device 10 regards base station candidates as a set of nodes and forms a network graph. The station location design device 10 applies the VoteRank algorithm (Non-Patent Document 4) to compare the terminal capacity between adjacent base station candidates on the network graph and votes (distributes) to adjacent base station candidates that have a terminal capacity greater than that of each base station candidate. The station location design device 10 repeats the process of selecting a group of base station candidates with the highest scores from the voting results as the placement locations of the base stations until all terminals are accommodated.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing an example of the hardware configuration of a station placement design device 10 in an embodiment of the present invention. The station placement design device 10 in Fig. 1 includes a drive device 100, an auxiliary storage device 102, a memory device 103, a processor 104, and an interface device 105, which are all interconnected by a bus B.

[0012] A program that realizes the processing in the station placement design device 10 is provided by a recording medium 101 such as a CD-ROM. When the recording medium 101 storing the program is set in the drive device 100, the program is installed from the recording medium 101 to the auxiliary storage device 102 via the drive device 100. However, the program does not necessarily have to be installed from the recording medium 101, but may be downloaded from another computer via a network. The auxiliary storage device 102 stores the installed program as well as necessary files, data, etc.

[0013] When an instruction to start the program is received, the memory device 103 reads out and stores the program from the auxiliary storage device 102. The processor 104 is a CPU or a GPU (Graphics Processing Unit), or a CPU and a GPU, and executes functions related to the station design device 10 in accordance with the program stored in the memory device 103. The interface device 105 is used as an interface for connecting to a network.

[0014] Fig. 2 is a diagram showing an example of the functional configuration of a station location design device 10 according to an embodiment of the present invention. In Fig. 2, the station location design device 10 includes an initial placement unit 11, a graph generation unit 12, a received power calculation unit 13, an index value calculation unit 14, a base station placement selection unit 15, and an output unit 16. Each of these units is realized by a process executed by a processor 104 of one or more programs installed in the station location design device 10. The station location design device 10 also uses a data storage unit 121. The data storage unit 121 can be realized using, for example, an auxiliary storage device 102 or a storage device connectable to the station location design device 10 via a network.

[0015] The following describes the processing procedure of the station placement design device 10 in Fig. 1. Fig. 3 is a flowchart for explaining an example of the processing procedure executed by the station placement design device 10.

[0016] In step S101, the initial placement unit 11 places multiple terminals and multiple base station candidates in a target area (hereinafter referred to as a "target area") for placement of a wireless base station (hereinafter simply referred to as a "base station") in a coordinate space (hereinafter referred to as a "target coordinate system A") corresponding to the target area. The terminals serve as points (evaluation points) for evaluating the reception status of radio waves from each base station. Therefore, the placement positions of the terminals in step S101 may differ from their actual placement positions. For example, the geographical distribution of terminals that are desired to be able to be accommodated simultaneously may be considered, and the position of each terminal may be determined based on the results of the consideration. The base station candidate refers to a candidate for the placement position of a base station. For example, the distribution of base stations that are estimated to be able to accommodate each terminal simultaneously may be considered, and the position of each base station candidate may be determined based on the results of the consideration.

[0017] As the terminals and base station candidates are placed, the initial placement unit 11 places each base station in a provisional placement state and each terminal in an unaccommodated state. The provisional placement state refers to a state in which the base station has not been selected as a placement location for the base station. The unaccommodated state refers to a state in which the terminal is not accommodated by any of the base station candidates. The placement locations of each base station candidate and each terminal are stored in advance in the data storage unit 121. Note that the data storage unit 121 may also store the placement locations of objects that block radio waves, such as buildings (hereinafter referred to as "blocking objects, etc."), in the target area. In this case, the initial placement unit 11 also places the blocking objects, etc. in the target coordinate system.

[0018] 4 is a diagram showing an example of the arrangement of base station candidates and terminals, in which a plurality of base station candidates, a plurality of terminals, and obstructions are arranged in a target coordinate system A.

[0019] Next, the graph generation unit 12 generates a network graph G according to the given network topology information, with each base station candidate as a node set (S102). The network topology information is information indicating the connection relationships between nodes (between base station candidates) in the network graph G, and is stored, for example, in the data storage unit 121. For example, connection relationships (edges in the network graph G) are set between base station candidates having a predetermined positional relationship. More specifically, connection relationships may be set between base station candidates whose physical (geographical) distance between them is equal to or less than a threshold. Alternatively, connection relationships may be set between base station candidates whose radio wave coverage areas overlap by a certain amount or more.

[0020] FIG. 5 is a diagram showing an example of a network graph G. In FIG. 5, the same parts as in FIG. 4 are given the same reference numerals. In FIG. 5, a network graph G is added to a target coordinate system A. FIG. 5 shows an example in which nodes are connected in accordance with topology information in which adjacent base stations in both the vertical and horizontal directions are connected in a grid pattern. In other words, the connection relationships set in the topology information form edges between each of the base station candidates. 5 shows an example in which the nodes (base stations) are connected in a grid pattern, but the nodes may be connected in other patterns. For example, topology information may be provided so that a mesh-shaped network graph is generated by connecting all adjacent nodes, including those in diagonal directions, or topology information may be provided so that a network graph is generated in which nodes are connected randomly (with a certain probability).

[0021] Next, the received power calculation unit 13 calculates an estimate of the received power (hereinafter referred to as "received power value") from each base station candidate at each terminal (each evaluation point) based on the wireless communication system of the base station planned to be deployed at each base station candidate and the corresponding antenna pattern (S103). In FIG. 6, the estimate of the received power value between base station b1 and terminal t1 is indicated by a dashed line. Note that the calculation of the received power value can be performed using a known radio wave propagation estimation technique or the like. The parameters required for the calculation (for example, radio parameters of the base station, etc.) may be stored in advance in the data storage unit 121.

[0022] Subsequently, the index value calculation unit 14 determines whether there is a terminal in an unaccommodated state (S104). Initially, all terminals are in an unaccommodated state (Yes in S104), so the process proceeds to step S105.

[0023] In step S105, the index value calculation unit 14 determines whether or not there are any base station candidates in a temporary deployment state (S105). Initially, all base station candidates are in a temporary deployment state (Yes in S105), so the process proceeds to step S106.

[0024] In step S106, the index value calculation unit 14 calculates the "terminal capacity per cost" for each base station candidate in the tentative allocation state.

[0025] The cost refers to the initial cost of the base station device (initial investment cost required to install a base station) that is set in advance for each base station candidate and stored in the data storage unit 121. "Terminal capacity per cost" = terminal capacity / cost. In this embodiment, "terminal capacity per cost" is an example of an index value based on the number of terminals that can be accommodated when a base station is deployed at the base station candidate. Note that when cost does not need to be taken into consideration, the terminal capacity may be used as the "terminal capacity per cost" below. In other words, the terminal capacity may be used as an index value based on the number of terminals that can be accommodated when a base station is deployed at the base station candidate. In this case, cost = 1.

[0026] The terminal capacity of a certain base station candidate refers to the number of terminals in an unserved state that the base station candidate can accommodate at the current (or current) time if a base station is deployed at that base station candidate. The number of terminals in an unserved state that a certain base station candidate can accommodate can be calculated by calculating a throughput expectation value for each terminal in an unserved state based on the received power value from the base station candidate, and counting terminals for which the expected value is equal to or greater than a target value. However, the maximum number of terminals in an unserved state that a certain base station candidate can accommodate is the upper limit of the number of servicable terminals stored in the data storage unit 121 for that base station candidate. Note that overlapping of terminals in an unserved state that can be accommodated by each base station candidate is permitted. Terminals that are deemed servicable for a certain base station candidate may be counted as servicable for other base station candidates. In other words, the total number of terminals in an unserved state that each base station candidate can accommodate may exceed the total number of terminals that are currently unserved.

[0027] Next, the base station placement selection unit 15 executes voting processing (hereinafter simply referred to as "voting processing") based on a relative comparison of "terminal capacity per cost" between adjacent base station candidates on the network graph G (S107). The voting processing is a process of comparing the "terminal capacity per cost" between adjacent base stations on the network graph G, and having each base station candidate divide (distribute) its own points of 1.0 in a predetermined manner to adjacent base station candidates that are superior to the base station candidate in question. The score of each base station candidate is calculated by adding up the values voted for by other base station candidates. The score is an evaluation value used to evaluate the priority (superiority or inferiority) of each base station candidate when selecting the placement location of the base station.

[0028] The details of step S107 will now be described. Fig. 7 is a flowchart illustrating an example of the processing procedure of the voting process.

[0029] In step S201, the base station placement selection unit 15 assigns a node set of the network graph G to a variable N.

[0030] Next, for each node u that is an element of N, the base station placement selection unit 15 calculates the score s u is initialized to 0 (S202). In the explanation of FIG. 7, node u corresponds to the u-th base station candidate.

[0031] Next, for each node u that is an element of N, the base station placement selection unit 15 calculates the "terminal accommodation capacity per cost" of the node u as a variable T u (S203).

[0032] Subsequently, the base station placement selection unit 15 executes a loop process L1 including steps S204 to S209 for each node u that is an element of N. The node u that is the processing target in the loop process L1 will be simply referred to as node u.

[0033] In step S204, the base station placement selection unit 15 sets the set of adjacent nodes v of node u as a variable N vAn adjacent node v of node u is another node connected to node u by one edge (one hop).

[0034] Next, the base station placement selection unit 15 calculates the variable N + u is initialized to an empty set (S205). + u is the set of neighboring nodes N v This is a variable to store the node v to which node u will vote.

[0035] Next, the base station placement selection unit 15 selects N v For each node v that is an element of the loop L2, a loop L2 including steps S06 and S207 is executed. The node v that is the processing target in the loop L2 will be simply referred to as the node v.

[0036] In step S206, the base station placement selection unit 15 calculates T u and T, the "terminal capacity per cost" of node v. v Compare with.

[0037] T u T than v If N is larger (Yes in S206), the base station placement selection unit 15 + u Add a node v to T (S207). u T v If it is equal to or greater than (No in S206), node v is + u is not added to.

[0038] All nodes v∈N v When the loop process L2 is completed for node u, the base station placement selection unit 15 performs the + u Value va to vote for u→v to 1.0 / |N + u (S208). Here, |N + u| is N + u is the number of elements in |N + u | is the total number of neighboring nodes v that have a larger "terminal capacity per cost" than node u. Therefore, the value obtained by dividing 1.0 (node u's points) by the total number is the value that is allocated from node u to each node v∈N + u However, the base station placement selection unit 15 selects the value to be voted for each node v∈N + u The "terminal capacity per cost" of each node v∈N + u The value obtained by dividing the total number of nodes by the total number of nodes (i.e., the relative ratio of the number of nodes per cost) may be used as the vote value from node u to each node v. For example, |N + u |=3 and N + u If the ratio of the "terminal capacity per cost" of the nodes v, which are elements of [mathematical formula - see original document], is 1:1:2, the values voted for each node v may be 0.25, 0.25, and 0.5, in order.

[0039] Next, the base station placement selection unit 15 selects each node v∈N v Scores of v Tova u→v is added (S209).

[0040] When the loop process L1 is executed for all elements (nodes u) of the node set N, the processing procedure in FIG. 7 ends. As a result, the score s u is aggregated (calculated).

[0041] Fig. 8 is a diagram showing an example of the results of tallying the scores for each base station candidate. In Fig. 8, #X (X=1 to 15) is an identifier for each base station candidate.

[0042] The base station placement selection unit 15 calculates the score s of the node u. umay be normalized by the degree of node u (the number of edges connected to u). Specifically, the base station placement selection unit 15 normalizes s u The score s of node u is calculated by dividing by the degree of node u. u It may also be possible to use the following.

[0043] Returning to FIG. 3, after step S107, the base station placement selection unit 15 calculates the score s u The state of the top part (up to m-th) of base station candidates is changed from the provisional deployment state to the deployment state (S108). That is, the base station deployment selection unit 15 selects the base station candidates as the deployment positions of the base stations.

[0044] Here, the value of m may be determined, for example, by one of the following methods. (1) It is preset as a fixed value (for example, m=2). (2) Change the value each time step S108 is executed (for example, first time: m=3, second time: m=2, third time onwards: m=1). (3) Divide the percentage of unaccommodated terminals by a specified value and round up to the nearest whole number (e.g., m = 0.5 ÷ 0.2 = 2.5 → 3).

[0045] In particular, (2) and (3) can increase the number of installations (the number of base station candidates that will be in a deployment state) at one time in the first half of the iterative process after step S104, and gradually reduce the number of installations as the iterative process progresses, which is expected to achieve both efficiency and accuracy.

[0046] Next, the base station allocation selection unit 15 selects terminals to be accommodated by each newly allocated base station candidate, and places the selected terminals in an accommodated state (S109). Specifically, for each unaccommodated terminal, the base station allocation selection unit 15 calculates an expected value (estimated value) of throughput when the terminal connects to each newly allocated base station candidate based on the received power value calculated for each newly allocated base station candidate in step S103. The base station allocation selection unit 15 accommodates terminals to base station candidates based on the rule that a terminal whose calculated expected value is equal to or greater than a threshold (target value) is accommodated in the base station candidate with the largest expected value among base station candidates that already accommodate the number of terminals less than the upper limit.

[0047] Note that if there are m+1 or more base station candidates up to the mth in descending score order, the base station placement selection unit 15 may, for example, at this timing, narrow down the m+1 or more base station candidates to m using the received power value of the terminal selected as an accommodation target for each base station candidate. Specifically, the base station placement selection unit 15 compares the minimum received power values of the terminal selected as an accommodation target for the base station candidates arranged with the lowest scores among the m+1 or more base station candidates, and narrows down the base station candidates up to the mth in descending order of minimum values. The base station placement selection unit 15 returns the states of the m+1 or later base station candidates to the provisional placement state, and does not change the states of the terminals selected as accommodation targets for these base station candidates to the accommodation state.

[0048] Next, the base station placement selection unit 15 deletes the nodes corresponding to the m base station candidates that have been newly placed and the edges connecting to the nodes from the network graph G (S110).

[0049] Subsequently, the base station placement selection unit 15 repeats step S104 and subsequent steps. In this case, since the number of unaccommodated terminals has changed in step S106, the "terminal accommodation capacity per cost" calculated for each base station candidate in the tentative placement state may change from the previous time.

[0050] In the process of repeating step S104 and subsequent steps, when there are no more terminals in an unaccommodated state (No in S104), the output unit 16 outputs, for example, a list of location information of deployed base station candidates (S111). In this case, the station placement design is considered successful and the processing procedure in Fig. 3 ends. That is, step S104 and subsequent steps are repeated for base station candidates that have not been selected as base station placement locations until all terminals are accommodated.

[0051] On the other hand, even if there are still unaccommodated terminals (No in S104), if all base stations are deployed (No in S105), the station placement design is deemed a failure and the processing procedure in Figure 3 ends. This is because there are terminals that cannot be accommodated. In this case, it is necessary to review the locations and number of base station candidate locations.

[0052] As described above, according to this embodiment, m base stations are placed in the repeated process, so that it is not necessary to repeat the process as many times as the number of base stations to be installed. Therefore, it is possible to shorten the calculation processing time required for wireless station design. As a result, it is possible to improve the efficiency of wireless station design for a large-scale environment (space).

[0053] Although it is possible to select a group of base station candidates with the top m evaluation values using conventional technology (greedy method), the terminals accommodated by the m selected base station candidates overlap, making it difficult to select an appropriate group of base station candidates.

[0054] On the other hand, according to this embodiment, adjacent base station candidates vote for each other to evaluate their relative merits, which reduces the overlap of accommodated terminals between selected base station candidates and enables the selection of an appropriate group of base station candidates.

[0055] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0056] 10 Station location design device 11 Initial placement section 12 Graph Generation Unit 13 Received power calculation unit 14 Index value calculation section 15 Base station location selection unit 16 Output section 100 Drive device 101 Recording media 102 Auxiliary storage 103 Memory Device 104 processors 105 Interface Device 121 Data storage unit B Bus

Claims

1. an index value calculation unit configured to calculate, for each of the base station candidates in a space in which a plurality of unaccommodated terminals and a plurality of base station candidates are arranged, an index value based on the number of the unaccommodated terminals that can be accommodated when a base station is arranged at the base station candidate; a base station placement selection unit configured to distribute points of the base station candidate to the other base station candidates having higher index values than the base station candidate among one or more other base station candidates having a predetermined positional relationship with the base station candidate, for each of the base station candidates, select some of the base station candidates having higher total sums of values distributed from the other base station candidates as placement locations of the base stations, and place the terminals that can be accommodated by the some of the base station candidates in an accommodating state in an accommodating state; A station placement design device comprising:

2. the index value calculation unit is configured to repeatedly calculate the index value for the base station candidate that has not been selected as a base station placement location until all of the terminals are accommodated, the base station placement selection unit is configured to distribute the points for the base station candidates that have not been selected as placement locations of base stations, select some of the base station candidates, and place the terminals that are not in a state of being accommodated and that can be accommodated by some of the base station candidates in an accommodating state, each time the index value is calculated.

2. The station placement design device according to claim 1.

3. The index value is the number of unaccommodated terminals that can be accommodated when a base station is installed at the base station candidate per cost related to the installation of the base station at the base station candidate.

3. The station placement design device according to claim 1 or 2.

4. a generating unit configured to generate a network graph having the base station candidates as nodes and edges between the base station candidates having the predetermined positional relationship, the base station placement selection unit is configured to distribute points of the node to adjacent nodes of the node that have higher index values than the node among the adjacent nodes of the node for each of the nodes, select some of the nodes with higher total sums of values distributed from the adjacent nodes as placement locations of the base stations, and place the terminals that are not yet accommodated and that can be accommodated by the base station candidates related to the some of the nodes into an accommodated state.

2. The station placement design device according to claim 1.

5. an index value calculation step of calculating, for each of the base station candidates in a space where a plurality of unaccommodated terminals and a plurality of base station candidates are arranged, an index value based on the number of the unaccommodated terminals that can be accommodated when the base station is arranged at the base station candidate; a selection procedure for allocating points of the base station candidate to one or more other base station candidates having a predetermined positional relationship with the base station candidate and having a higher index value than the base station candidate, selecting some of the base station candidates having a higher total sum of values allocated from the other base station candidates as base station locations, and placing the terminals that can be accommodated by the some of the base station candidates in an accommodated state while not being accommodated; A station placement design method characterized by being executed by a computer.

6. an index value calculation step of calculating, for each of the base station candidates in a space where a plurality of unaccommodated terminals and a plurality of base station candidates are arranged, an index value based on the number of the unaccommodated terminals that can be accommodated when the base station is arranged at the base station candidate; a selection procedure for allocating points of the base station candidate to one or more other base station candidates having a predetermined positional relationship with the base station candidate and having a higher index value than the base station candidate, selecting some of the base station candidates having a higher total sum of values allocated from the other base station candidates as base station locations, and placing the terminals that can be accommodated by the some of the base station candidates in an accommodated state while not being accommodated; A program characterized by causing a computer to execute the above.

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