Site location design device and site location design method
By compressing weighted graphs of terminal and base station connections, the method reduces computational complexity in base station placement, ensuring consistent communication quality in dynamic environments.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NIPPON TELEGRAPH & TELEPHONE CORP
- Filing Date
- 2024-10-15
- Publication Date
- 2026-04-27
AI Technical Summary
Existing base station placement methods struggle with high computational demands in environments where terminal usage varies over time, leading to inefficiencies and increased costs.
A method that compresses weighted directed graphs representing terminal and base station connections over time to reduce computational load, allowing robust placement design with fewer base stations.
Enables efficient and robust base station placement with reduced computation, maintaining communication quality despite varying terminal usage patterns.
Smart Images
Figure 2026070313000001_ABST
Abstract
Description
[Technical Field]
[0001] This disclosure relates to a base station placement design device and a base station placement design method for determining the placement location of a base station. [Background technology]
[0002] The range of radio waves that can reach from a base station is limited. Furthermore, the number of terminals that a single base station can accommodate is also limited. Therefore, if the number of base stations is insufficient, problems such as inadequate coverage and insufficient terminal capacity will arise. On the other hand, if the number of base stations is excessive, it becomes inefficient due to increased costs for the base station equipment itself, as well as for installation and operation. For these reasons, when determining the placement of base stations, it is necessary to place a sufficient number of base stations in appropriate locations, and various base station placement design methods, such as those disclosed in Non-Patent Document 1, are being considered.
[0003] Incidentally, as disclosed in Non-Patent Document 2, for example, the use of wireless communication systems in factories is increasing with the spread of IoT. In such an environment, the conditions for site design, such as the location of wireless communication network use, can change significantly.
[0004] In this regard, for example, Non-Patent Document 3 discusses a base station design method using terminal presence probability assuming fluctuations in communication location. Specifically, in the base station design method disclosed in Non-Patent Document 3, the coordinates and presence probability of terminals are set from the assumed communication locations of terminals within the design target area. Furthermore, base station installation candidates are set, and the received power from each base station installation candidate for each terminal is calculated. Then, one base station is selected from the unplaced base station installation candidates that maximizes the sum of the presence probabilities of terminals that are above the quality target value, and is marked as placed. This process is repeated while increasing the number of base stations until the sum of the presence probabilities of terminals that are above the quality target value exceeds the design target value.
[0005] In an environment where the usage status of terminals varies over time, a robust placement design is required. However, in the above placement design method, as the number of patterns of terminal placement increases, the computational amount of the computer for placement design increases proportionally.
Prior Art Documents
Non-Patent Documents
[0006]
Non-Patent Document 1
Non-Patent Document 2
Non-Patent Document 3
Non-Patent Document 4
Summary of the Invention
Problems to be Solved by the Invention
[0007] This disclosure has been made paying attention to the above circumstances, and an object thereof is to provide a technology capable of performing a robust placement design with a small amount of computation in an environment where the usage status of terminals varies over time.
Means for Solving the Problem
[0008] To achieve the above object, a placement design device according to one embodiment of the present disclosure is configured as follows. This placement design device is a device that determines the placement positions of base stations within a design target area, and includes a processor and a memory that stores a plurality of instructions executable by the processor. The plurality of instructions are configured to cause the processor to execute the following processes. The first process is to arrange a plurality of base station installation candidates within the design target area. The second process is to calculate the radio quality between each terminal and each base station installation candidate for each time step based on the movement prediction of a plurality of terminals within the design target area for each time step. The third process is to create a weighted directed graph for each time step with each terminal as a node, the connection between each terminal and each base station installation candidate as an edge, and each radio quality as the weight of each edge, and obtain a graph set. The fourth process is to compress the graph set in the time direction to obtain a compressed graph set. And the fifth process is to select the placement positions of the base stations from the plurality of base station installation candidates based on the compressed graph set such that the total probability of the existence of terminals with radio quality equal to or higher than the quality target value is equal to or higher than the design value target value.
[0009] To achieve the above objective, a base station placement design method according to one embodiment of the present disclosure is a method for determining the placement location of a base station within a design target area, and includes the following processes to be executed by a computer. The first process is to place a plurality of base station placement candidates within the design target area. The second process is to calculate the radio quality between each terminal and each base station placement candidate for each time step based on the movement prediction of the plurality of terminals within the design target area. The third process is to create a weighted directed graph for each time step, where each terminal is a node, the connection between each terminal and each base station placement candidate is an edge, and each radio quality is the weight of each edge, and to obtain a set of graphs. The fourth process is to compress the set of graphs in the time direction to obtain a compressed set of graphs. The fifth process is to select a base station placement location from a plurality of base station placement candidates based on the compressed set of graphs such that the sum of the probabilities of the existence of terminals whose radio quality is equal to or greater than the quality target value is equal to or greater than the design target value.
[0010] To achieve the above objectives, a site design program according to one embodiment of this disclosure is configured to cause a computer to execute the site design method described above. More specifically, this site design program includes a plurality of instructions for causing a computer to execute the first to fifth processes described above. This site design program may be stored on a computer-readable storage medium or provided via a communication network. [Effects of the Invention]
[0011] According to the technology described in this disclosure, robust site placement design can be performed with less computation in environments where terminal usage fluctuates over time. [Brief explanation of the drawing]
[0012] [Figure 1] This diagram schematically illustrates the key points of station site design. [Figure 2] This diagram schematically illustrates the key points of station site design. [Figure 3]This is a flowchart showing the initial steps in the site design procedure. [Figure 4] This is a flowchart showing the later stages of the site design procedure. [Figure 5] This is a block diagram showing an example of the configuration of a site location design device. [Modes for carrying out the invention]
[0013] 1. Key points for site design First, let me explain the key points of the base station design proposed in this disclosure. The base station design proposed in this disclosure expresses the variation in the communication location of terminals as a terminal presence probability and uses this as input information to determine the placement location of the base station. With such a base station design, by considering multiple terminal placement conditions simultaneously, it is possible to ensure the necessary communication quality even if the terminal placement changes. Increasing the number of assumed terminal placement conditions will improve robustness against variations in terminal placement. However, as discussed regarding the base station design method described in Non-Patent Document 3, there is a trade-off that the more terminal placement patterns there are, the more the amount of computer computation required for base station design increases proportionally.
[0014] The key point of the site placement design proposed in this disclosure lies in the ingenuity to eliminate the aforementioned conflict. According to the site placement design proposed in this disclosure, instead of each of the assumed terminal placement conditions being used as individual input information, aggregated information is created by combining them, and this aggregated information is used as input information. The process of creating the aggregated information used as input information is schematically represented in Figures 1 and 2.
[0015] First, as shown in Figure 1, based on the assumed terminal placement conditions and base station installation candidates, each terminal and each base station installation candidate are connected in a mesh, and the wireless quality between the base station installation candidates and terminals is represented by a weighted directed graph (hereinafter also simply referred to as the graph). This graph G is a graph in which each terminal is a node V, the connection between each terminal and each base station installation candidate is an edge, and the received quality between each terminal and each base station installation candidate is the weight.
[0016] As shown in Figure 2, a graph representing the wireless quality between base station installation candidates and terminals is created at predetermined time steps. Then, a set of graphs g is obtained for each time step. Next, the number of graphs is reduced by compressing the set of graphs g in the time direction. In the compression of the set of graphs g, graphs with similarity are sequentially merged. In the base station design proposed in this disclosure, the placement location of the base station is determined using the compressed set of graphs g' obtained by this process as input information. Note that in Figure 2, in order to simplify the graph representation, lines connecting each terminal and each base station installation candidate are omitted except for the line showing the edge with the maximum weight.
[0017] The amount of computer computation required for site placement design is proportional to the number of graphs used as input information. Therefore, according to the site placement design proposed in this disclosure, even if the number of terminal placement patterns increases, the increase in the amount of computer computation required for site placement design can be suppressed by generating and compressing the graph set as described above. In other words, according to the site placement design proposed in this disclosure, a robust site placement design can be performed with less computation in environments where terminal usage changes over time.
[0018] 2. Site Design Procedure Next, the site location design procedure will be explained using the flowcharts in Figures 3 and 4. The flowchart in Figure 3 shows the initial part of the site location design procedure, and the flowchart in Figure 4 shows the later part of the site location design procedure. A site location design method according to one embodiment of this disclosure is reflected in this series of steps.
[0019] In the preliminary part of the station design procedure, the process in step S11 is performed first. In step S11, based on the movement prediction of each terminal i (i∈V) within the design target area, each time step t (t={t1,t2,···,t TThe coordinates of each terminal in}) are generated. The method of movement prediction is not particularly limited, and various known methods can be used. Note that the coordinates of each terminal are required when a propagation model, ray tracing, etc. are used to calculate the received power in the next step. However, if the received power on the terminal side can be prepared by another method such as using measured values, the coordinates of the terminal are not necessary, and in that case, the process of step S11 may be omitted.
[0020] Next, in step S12, a base station installation candidate j is arranged within the design target area. And the received power w i,j (w i,j ∈W) at each time step t received by each terminal i from each base station installation candidate j is calculated. There is no particular limitation on the number of arranged base station installation candidates j. When optimizing the antenna direction of the device and the type of antenna used for the base station, different base station installation candidates can be set for each of those parameters. In that case, multiple base station installation candidates are arranged at one arrangement position, and the received power w i,j is calculated for each parameter. Note that the received power is an example of the radio quality between each terminal i and each base station installation candidate j that can be used as the weight W of the graph. For example, the received SNR may be used as the weight W of the graph instead of the received power.
[0021] Next, in step S13, a weighted directed graph G (G = (V, E, W)) for each time step t is created. However, the edge E is the connection e i,j (e i,j ∈E) between each terminal i and each base station installation candidate j. And a graph set g (g = {G1, G2, ···, G T}}) which is a set of those graphs G is obtained.
[0022] Next, in step S14, a compressed graph set g´ is obtained by compressing the graph set g in the time direction. In this process, first, pairs of consecutive time steps ((t1, t2), (t2, t3), ···, (t T-1 , t T )) corresponding two graphs G i and Gj The difference in the graph Δ(G i ,G j ) is calculated. When the pair of time steps is (t1, t2), the graph difference is Δ(G1, G2), and when the pair of time steps is (t T-1 ,t T In the case of ), the graph difference is Δ(G T-1 ,G T ) is the case here. Here, the graph difference Δ(G i ,G j ) is defined, for example, by the following formula:
number
[0023] Note that in the above formula, w e i and lol e j This is graph G with respect to edge e. i and graph G j This is the weight of |w e i -w e j | represents the absolute difference in the weights of both graphs for edge e. Σ e |ε represents the sum over all edges e. i | is graph G i This represents the number of edges of graph G. In other words, the above formula is equivalent to graph G i and graph G j This formula calculates the average difference in edge weights. By comprehensively evaluating the differences in edge weights across the entire graph and dividing it by the number of edges, we can show the average difference for each edge.
[0024] Furthermore, in step S14, the graph difference Δ(G i ,G j ) are sorted by size, and the graph difference Δ(G i ,G j Two graphs G where the time steps are consecutive in ascending order of ) i and G jThe graphs are merged. The merging of the graphs is carried out by the following procedure, for example, disclosed in Non-Patent Document 4. First, two graphs G with consecutive time steps are merged. i and G j Each of the adjacency matrices A i and A j Next, the adjacency matrix A is obtained. i and A j The average is calculated. Then, the adjacency matrix A after averaging is calculated. k (A k =( A i +A j Graph G after the merger of each component of ) / 2). k This is calculated as the weight of each edge. Note that there are various methods for compressing multiple graphs as time-series data into one or a few graphs, other than the method disclosed in Non-Patent Document 4. Other methods besides the one disclosed in Non-Patent Document 4 are also applicable to the location design proposed in this disclosure.
[0025] In step S14, the graph merging process described above is repeatedly performed until the size of the compressed graph set g' is reduced to a predetermined size, that is, until the total number of graphs included in the compressed graph set g' is reduced to a predetermined number.
[0026] Once the desired set of compressed graphs g' is obtained, the base station design procedure then moves from the preliminary stage shown in Figure 3 to the subsequent stage shown in Figure 4. In the subsequent stage of the base station design procedure, the process in step S15 is performed first. In step S15, based on the set of compressed graphs g' obtained in step S14, one base station location candidate is selected from the base station location candidates that do not yet have a base station, and the candidate that maximizes the sum of the probabilities of terminals whose radio quality is equal to or greater than the quality target value is selected. Then, a base station is placed at the selected base station location candidate, and the selected base station location candidate is marked as having a base station placed.
[0027] Next, in step S16, it is determined whether the sum of the probabilities of terminals with radio quality equal to or greater than the quality target value is equal to or greater than the design target value. If the sum of the probabilities of such terminals does not reach or greater than the design target value, the process in step S15 is performed again, and base stations are placed in the unplaced base station installation candidates. If the design target value is achieved, the process in step S17 is performed. In step S17, the placement location of the base stations in the base station installation candidates, i.e., the site placement design result, is determined.
[0028] 3. Configuration of the site design device The above site design procedure can be performed by a computer. Figure 5 is a block diagram showing an example of the configuration of a site design device that includes a computer for performing the site design procedure.
[0029] The base station design device 10 comprises a communication unit 11, an external input unit 12, a processing unit 13, and a database 16. The communication unit 11 communicates with an input / display device 20 located outside the base station design device 10 via wired or wireless connection. The input / display device 20 accepts information input from the operator and displays the input information and information output from the base station design device 10 on a display. Initial values for the expected communication locations of terminals and candidate base station locations are input to the input / display device 20 by the operator.
[0030] The external input unit 12 is an interface between the communication unit 11 and the processing unit 13, and the communication unit 11 inputs information received from the input / display device 20 to the processing unit 13. The external input unit 12 also outputs information obtained from the calculation processing by the processing unit 13 to the communication unit 11, and transmits it to the input / display device 20 via the communication unit 11.
[0031] The processing unit 13 comprises a processor 14 and memory 15. The processor 14 is typically a CPU. Memory 15 stores a program that can be executed by the processor 14. The program consists of multiple instructions for the processor 14 to perform the above-described base station design procedure. By executing the above-described base station design procedure on the processor 14, the determined base station placement location is obtained. The program can be stored on a computer-readable storage medium. The program can also be provided via a communication network.
[0032] Database 16 stores the base station locations obtained by calculations performed by the processing unit 13. The base station locations stored in database 16 can be read from database 16 by the operator operating the input / display device 20. The base station locations read from database 16 can be displayed on the input / display device 20 or transmitted externally via the communication network.
[0033] 4. Others The embodiments described above can be modified in various ways without departing from the gist of this disclosure. That is, where the number of elements, quantities, amounts, ranges, etc., are referred to in the embodiments above, the technology of this disclosure is not limited to the number referred to, unless otherwise explicitly stated or clearly defined in principle. Furthermore, the structures, etc., described in the embodiments above are not necessarily essential to the technology of this disclosure, unless otherwise explicitly stated or clearly defined in principle. [Explanation of Symbols]
[0034] 10 Station design device, 11 Communication unit, 12 External input unit, 13 Processing unit, 14 Processor, 15 Memory, 16 Database
Claims
1. A base station placement design device that determines the placement location of base stations within a design target area, Processor and The system comprises a memory that stores a plurality of instructions that can be executed by the aforementioned processor, The aforementioned multiple instructions are, Placing multiple base station installation candidates within the aforementioned design target area, Based on the predicted movement of multiple terminals within the design target area, the wireless quality between each terminal and each base station installation candidate is calculated for each time step, This involves creating a weighted directed graph for each time step, where each terminal is a node, the connection between each terminal and each base station installation candidate is an edge, and each wireless quality is the weight of each edge, and then obtaining the set of graphs. The aforementioned set of graphs is compressed in the time direction to obtain a compressed set of graphs, The system is configured to have the processor perform the following actions: select the placement location from the plurality of base station installation candidates based on the compressed graph set, such that the sum of the probabilities of the existence of terminals whose wireless quality is equal to or greater than the quality target value is equal to or greater than the design target value. A station location design device characterized by the following features.
2. In the site design device according to claim 1, Compressing the aforementioned set of graphs in the time direction means Calculating the graph difference between two weighted directed graphs with consecutive time steps, Merging the two weighted directed graphs in which the time steps are consecutive in order of decreasing graph difference, This includes repeating the merger until the total number of weighted directed graphs reaches a predetermined number. A station location design device characterized by the following features.
3. In the location design device according to claim 2, Merging the two weighted directed graphs whose time steps are consecutive means The mean of the adjacency matrices of the two weighted directed graphs mentioned above, This includes calculating the weights of each edge in the merged weighted directed graph from each component of the averaged adjacency matrix. A station location design device characterized by the following features.
4. A base station placement design method for determining the placement location of base stations within a design area, Placing multiple base station installation candidates within the aforementioned design target area, Based on the predicted movement of multiple terminals within the design target area, the wireless quality between each terminal and each base station installation candidate is calculated for each time step, This involves creating a weighted directed graph for each time step, where each terminal is a node, the connection between each terminal and each base station installation candidate is an edge, and each wireless quality is the weight of each edge, and then obtaining the set of graphs. The aforementioned set of graphs is compressed in the time direction to obtain a compressed set of graphs, The computer is instructed to select the placement location from the multiple base station installation candidates based on the compressed graph set, such that the sum of the probabilities of the existence of terminals whose wireless quality is equal to or greater than the quality target value is equal to or greater than the design target value. A method for designing a station location, characterized by the following features.