JP6666308B2 - Station design method - Google Patents

Description

  The present invention is directed to a wireless communication system in which the number of terminal stations that can be simultaneously connected to one base station and the number of available wireless channels are finite, even if there is an area where terminal stations are densely packed. The present invention relates to a base station placement design method for accommodating all terminal stations.

  2. Description of the Related Art Conventionally, a communication service area is covered as a technique for designing a base station in a wireless communication system in which a plurality of base stations are arranged and a continuous communication service area is constructed by a communication area (cell) of each base station. Meanwhile, there has been proposed a station design method for equalizing traffic accommodated in each cell and enabling service provision with as few cells (base stations) as possible (Patent Document 1).

FIG. 6 shows an example of a conventional station design method.
In FIG. 6, assume that the maximum number of terminal stations that can be simultaneously connected to one base station is three in the assumed wireless communication system. The base station (▲) groups each to accommodate three terminal stations (□) and allocates a radio channel to each group so that radio interference does not occur between the groups. Here, in order to accommodate 15 terminal stations in any of the base stations, if each base station accommodates a maximum of 3 terminal stations, the minimum number of base stations corresponds to 5 groups and 5 groups. be able to. At this time, in order to prevent the occurrence of wireless interference between groups, the required number of wireless channels is three.

JP 2013-046362 A

  The conventional station design method is a technique such as a cellular system in which the area is centered on the base station. If the terminal stations are accommodated up to the maximum number that can be accommodated in the base station, the required number of base stations and groups is reduced. However, the number of wireless channels for avoiding wireless interference between groups tends to increase. Further, depending on the density of the terminal stations, there is a possibility that some base stations cannot accommodate all the terminal stations.

  On the other hand, if station placement is designed around the terminal stations to be accommodated, the number of base stations and groups will increase, but the number of radio channels to avoid radio interference between groups will be reduced, and the antenna directivity and transmission of base stations will be reduced. If the power is controlled, the number of wireless channels can be further reduced while avoiding wireless interference with adjacent groups.

  For example, FIG. 7 shows that, in the same arrangement of base stations (▲) and terminal stations (□) as in FIG. 6, a group is formed even if the number of base stations is less than the maximum capacity, and the antenna directivity indicated by the arrow is taken into consideration. By doing so, an example will be described in which wireless channels can be assigned so that wireless interference does not occur between groups even with two channels.

  The present invention performs grouping of terminal stations based on propagation loss between terminal stations, and assigns a wireless channel to each group in consideration of wireless interference, thereby enabling accommodation of many terminal stations with a small number of wireless channels. It is an object of the present invention to provide a station design method.

  In the present invention, a set of terminal stations that can be simultaneously accommodated by a plurality of base stations is grouped, and a terminal station accommodated in each group and a radio channel to be assigned to each group are designed so that there is no radio interference between the groups. In the station design method, all terminal stations to be station-designed are within the maximum accommodation number M of base stations (M is an integer of 2 or more), based on propagation loss between terminal stations and the presence / absence of base stations capable of simultaneous accommodation. Step 1 of generating a plurality of grouping patterns by changing the terminal station as a starting point, and selecting one grouping pattern based on a predetermined condition from among the generated plurality of grouping patterns; A base station capable of accommodating each terminal station is selected for each group constituting the selected grouping pattern, and a directional antenna of the base station is selected. And a step 3 for assigning a no radio interference radio channels between groups while adjusting the antenna direction.

  In the station design method of the present invention, step 1 is to select a starting terminal station that is a starting point of a group of a grouping pattern and has a base station that can be accommodated, and selects a terminal terminal existing in the group as a second or later selected terminal station. Is minimized, and when there is a base station capable of accommodating the originating terminal station and the selected terminal station at the same time, the process of adding to the group is repeated until the grouping for all terminal stations of the station design is completed. A process for generating a grouping pattern is performed.

  In the station location design method of the present invention, step 1 is to select a terminal station having the minimum propagation loss between the terminal station and the originating terminal station as the second selected terminal station when the group existing terminal stations are only originating terminal stations. If there are a plurality of terminal stations in the selected group and there are a plurality of terminal stations existing in the group, the propagation loss L between the i-th terminal station (i is an integer equal to or greater than 3) and the (i-1) th terminal station, To select a terminal that minimizes the sum of the maximum propagation loss R with the terminal station.

  In the station design method of the present invention, step 1 performs a process in which a selected terminal station whose propagation loss between terminal stations in the group exceeds a specified value is not added to the group.

  In the station design method of the present invention, in the step 2, as a predetermined condition, the number of groups forming the grouping pattern is the minimum, or the maximum propagation loss between the terminal stations of each group forming the grouping pattern is the minimum.

  In the station design method of the present invention, step 3 performs a process of selecting a base station having the minimum transmission power that satisfies the reception level threshold of each terminal station as a base station capable of accommodating each terminal station for each group.

  In the station design method according to the present invention, if the predetermined number of radio channels cannot be used for the number of groups, step 3 is performed by thinning out the terminal group having the largest number of interfering terminal stations in the predetermined group or the group, and re-executing. Assign a wireless channel.

  In the station design method of the present invention, in step 3, when there are a plurality of wireless channel allocation patterns for each group, a process of selecting an allocation pattern that minimizes the number of wireless channels used in the entire grouping pattern is performed.

  The present invention performs grouping of terminal stations based on propagation loss between terminal stations, and assigns a wireless channel to each group in consideration of wireless interference. Station design that accommodates more terminal stations becomes possible.

It is a flowchart which shows the example of a processing procedure of the station setting design method of this invention. It is a flowchart which shows the example of a processing procedure of step S2 (one grouping pattern generation). FIG. 6 is a diagram illustrating an example of generating a group forming a grouping pattern. It is a flowchart which shows the example of a processing procedure of step S4 (base station selection and radio channel allocation). FIG. 3 is a diagram illustrating an example of wireless channel allocation for each group. FIG. 11 is a diagram illustrating an example of a conventional station design method. It is a figure which shows the example of allocation of the wireless channel by two channels.

FIG. 1 shows an example of the processing procedure of the station design method of the present invention.
In FIG. 1, first, radio wave propagation loss is calculated between base stations, between base stations and terminal stations, and in all sections between terminal stations according to the antenna direction of the directional antenna of the base station (S1).

  Next, all terminal stations to be station-designed are grouped so as not to overlap within the maximum accommodation number M of base stations, and the result is set as one grouping pattern. Is generated (S2).

  Here, the first terminal station accommodated in the group is referred to as “originating terminal station”, and the second to Mth terminal stations accommodated in the group are referred to as “selected terminal stations”. If there is no base station capable of accommodating the originating terminal station, a group including the originating terminal station cannot be formed.Therefore, the terminal station selected as the originating terminal station is excluded from the station design target and other terminal stations are excluded. Originating terminal station. If there is no base station capable of accommodating the originating terminal station of the first group of the grouping pattern, the grouping pattern starting from the originating terminal station does not hold, and the number of grouping patterns is reduced accordingly.

  The details will be described with reference to FIGS. 2 and 3. However, the number of terminal stations forming each group is not always limited to the maximum number M of base stations accommodated. In some cases, the terminal stations and the selected terminal stations together form a group of less than M terminal stations. Therefore, the number of groups forming each grouping pattern is not constant. One group is formed as long as there is a base station capable of accommodating all of the selected originating terminal station and the selected terminal station, but not in a physical distance but in a range in which the radio propagation loss between the terminal stations is equal to or less than a specified value. And Note that the specified value is a value corresponding to the communicable distance that determines the upper limit of the group area.

Next, one grouping pattern is selected from the plurality of grouping patterns by sequentially applying the following conditions (S3).
(1) The number of groups forming the grouping pattern is the smallest
(2) The maximum propagation loss R between the terminal stations of each group forming the grouping pattern is minimum.
(3) If there are multiple grouping patterns that satisfy the above conditions, the reference terminal station of the first group is

  Next, for the selected grouping pattern, a base station capable of accommodating all terminal stations forming the group is selected, and a wireless channel is assigned to each group so that there is no wireless interference between the groups (S4). Details will be described with reference to FIG.

FIG. 2 shows an example of a processing procedure of step S2 (one grouping pattern generation).
In FIG. 2, the starting terminal station of group n (n = 1) is selected from all terminal stations to be station-designed (S21). Next, it is determined whether there is a base station capable of accommodating the selected starting terminal station (S22). If there is no base station, a group including the selected starting terminal station and a grouping pattern cannot be formed. The terminal station selected as the station is excluded from the station design target (S22), and the process returns to step S21 to select another starting terminal station.

  If there is a base station that can accommodate the originating terminal station, the propagation loss L between the last terminal station (originally the originating terminal station) accommodated in group n and the candidate terminal station is selected as the selected terminal station accommodated in group n. And the candidate terminal station that minimizes the sum (L + R) of the maximum propagation loss R between the other terminal stations accommodated in the group n and the candidate terminal station is set as the next selected terminal station (S24).

  Next, it is determined whether or not the propagation loss (L and R) between the terminal stations of the group n does not exceed the specified value (S25), and if so, the selected terminal station selected is not added to the group n. The terminal stations accommodated in the group n are determined up to the last terminal station accommodated in the group n (initially the starting terminal station n) (S29). On the other hand, if the propagation loss (L and R) between the terminal stations of group n does not exceed the specified value, it is determined whether there is a base station that can simultaneously accommodate each terminal station including the selected terminal station of group n. A determination is made (S26). If the base station does not exist, the selected terminal station is not added to the group n, and the terminal stations to be accommodated in the group n are determined up to the last terminal station accommodated in the group n (originally the starting terminal station n). (S29).

  If there is a base station that can be accommodated in step S26, the selected terminal station is added to group n (S27), and it is determined whether the number of terminal stations accommodated in group n has reached the maximum accommodation number M of the group (S28). If not, the process returns to step S24 to select the next selected terminal station to be accommodated in group n.

  On the other hand, if the number of terminal stations accommodated in the group n has reached the maximum accommodation number M of the group, the terminal stations accommodated in the group n are determined (S29), and whether or not the grouping for all terminal stations has been completed is determined. A determination is made (S30). Here, if the grouping has not been completed, n = n + 1 to form the next group (S31), and the terminal station with the smallest propagation loss from the last terminal station of group n-1 is the starting terminal station of group n. n is selected (S32). Next, it is determined whether or not there is a base station capable of accommodating the selected starting terminal station (S33). If there is no base station, a group including the selected starting terminal station cannot be formed. The removed terminal station is excluded from the station design target (S34), and the process returns to step S32 to return to the last terminal station of the group n-1 from the other starting terminal stations having the minimum propagation loss (the smallest next to the excluded terminal station). Select

  If there is a base station that can accommodate the originating terminal station of the selected group n, the processing from step S24 is performed, and the selected terminal station accommodated in group n is selected. The above processing is repeated, and the terminal stations to be accommodated in the next group n + 1 are selected until grouping for all terminal stations is completed.

  Here, the procedure for generating the group 1 of the grouping pattern 1 will be specifically described with reference to FIG. The terminal stations A to F are shown as a part of all the terminal stations, and the maximum accommodation number M of the group is set to M = 4. The propagation loss between the terminal stations is indicated by a to n.

  First, terminal station A is selected as the originating terminal station of group 1 of grouping pattern 1, and it is determined whether there is a base station (not shown) that can accommodate originating terminal station A. If there is no base station capable of accommodating the originating terminal station A, the group including the originating terminal station A and the grouping pattern cannot be formed, so that it is excluded from the station design and the next terminal station B is selected as the originating terminal station of the group 1 I do. In this case, the result is the same as when group 1 of grouping pattern 2 starts from the originating terminal station B.

  If there is a base station capable of accommodating the originating terminal station A, the selected terminal station will be selected from the other terminal stations B, C, D, E and F, but the propagation losses a and b from the originating terminal station A will be selected. , C, d, and e, the terminal station B corresponding to the minimum propagation loss a is the selected terminal station. At this time, if the minimum propagation loss a exceeds the specified value in step S25, the terminal station B cannot be accommodated in the group 1 of the originating terminal station A, and the group 1 is determined only by the originating terminal station A. Therefore, in step S24, for example, the terminal stations E and F whose propagation losses d and e exceed the specified values may be excluded from the selection of the selected terminal station at this time. An example is shown as a grouping pattern 1 'in FIG.

  When the terminal station B is selected as the selected terminal station of the group 1, it is determined whether there is a base station that can simultaneously accommodate the originating terminal station A and the selected terminal station B accommodated in the group 1, and the base station If not, the group 1 is determined only by the originating terminal station A. If there is a base station that can simultaneously accommodate the originating terminal station A and the selected terminal station B, the selected terminal station B is added to the group 1. Up to this point, group 1 is two terminal stations, and the maximum number of terminals M has not reached M = 4. Therefore, the next selected terminal station is selected from the other terminal stations C, D, E, and F. The propagation losses f, g, h, and i from the selected terminal station B and the maximum propagation losses b, c, d, and e between the other terminal stations (here, the originating terminal station A) accommodated in the group 1 are as follows. Of the sums f + b, g + c, h + d, and i + e, the terminal station C corresponding to the minimum propagation loss sum f + b is the selected terminal station. In the example of the grouping pattern 1 'in FIG. 3, the maximum propagation loss b between the propagation loss f, g from the selected terminal station B and another terminal station (here, the starting terminal station A) accommodated in the group 1 is shown. , C, the terminal station C corresponding to the minimum propagation loss sum f + b among the sums f + b, g + c is the selected terminal station.

  When the terminal station C is selected as the selected terminal station of the group 1, it is determined whether or not there is a base station that can simultaneously accommodate the originating terminal station A and the selected terminal stations B and C accommodated in the group 1; If there is no station, the group 1 is determined only by the originating terminal station A and the selected terminal station B. If there is a base station that can simultaneously accommodate the originating terminal station A and the selected terminal stations B and C, the selected terminal station C is added to the group 1. Up to this point, group 1 has three terminal stations, and the maximum number of terminals M has not reached M = 4. Therefore, the next selected terminal station is selected from the other terminal stations D, E, and F. The maximum propagation loss c, d, e between the propagation loss j, k, l from the selected terminal station C and the other terminal stations (here, the originating terminal station A and the selected terminal station B) accommodated in the group 1 Of the respective sums j + c, k + d, and l + e, the terminal station D corresponding to the minimum propagation loss sum j + c is the selected terminal station. In the example of the grouping pattern 1 ′ in FIG. 3, the maximum between the propagation loss j from the selected terminal station C and the other terminal stations (here, the originating terminal station A and the selected terminal station B) accommodated in the group 1 is shown. The terminal station D corresponding to the propagation loss c and the sum j + c is the selected terminal station.

  When the terminal station D is selected as the selected terminal station of the group 1, it is determined whether there is a base station that can simultaneously accommodate the originating terminal station A and the selected terminal stations B, C, and D accommodated in the group 1, If the base station does not exist, the group 1 is determined only by the originating terminal station A and the selected terminal stations B and C. If there is a base station that can simultaneously accommodate the originating terminal station A and the selected terminal stations B, C, and D, the selected terminal station D is added to the group 1. Up to this point, group 1 has four terminal stations, and the maximum number of terminals M has reached M = 4. Thus, the four originating terminal stations A to be accommodated in group 1 and the selected terminal stations B, C, and D are determined.

  In the processing of steps S22 and S26, a base station capable of accommodating only the originating terminal station A, a base station capable of accommodating the originating terminal station A and the selected terminal station B simultaneously, the originating terminal station A and the selected terminal station B , C and the base station that can simultaneously accommodate the originating terminal station A and the selected terminal stations B, C, and D may be the same or different. Here, it is only confirmed whether or not the base station can be accommodated. Selection of a base station that can be actually accommodated is performed in step S4 shown in FIGS.

  When the terminal stations to be accommodated in group 1 are determined, grouping for group 2 is started because grouping for all terminal stations has not been completed.

  Either of the terminal stations E and F is selected as the originating terminal station of the group 2, but among the propagation losses m and n from the last terminal station D accommodated in the group 1, the terminal station E corresponding to the minimum propagation loss m Is selected as the originating terminal station, and it is determined whether there is a base station (not shown) that can accommodate the originating terminal station E. If there is no base station capable of accommodating the originating terminal station E, a group including the originating terminal station E cannot be formed. select. If there is a base station capable of accommodating the originating terminal station E, a selected terminal station accommodated in the group 2 is selected in the same manner. In FIG. 3, only the terminal station F is described, but the group is updated until all the terminal stations to be station-designed are accommodated in one of the groups or are excluded from the station-design target. Go. This accommodates the generation of grouping pattern 1.

  Regarding the grouping pattern 2, FIG. 3 shows an example in which if the terminal station B is selected as the originating terminal station of the group 1, the selected terminal stations E, D, and C are determined in order. Either of the terminal stations A and F is selected as the originating terminal station of the group 2, but among the propagation losses b and l from the last terminal station C accommodated in the group 1, the terminal station A corresponding to the minimum propagation loss b Is selected as the originating terminal station of group 2. The same applies hereinafter.

FIG. 4 shows a processing procedure example of step S3 (base station selection / wireless channel assignment).
In FIG. 4, for one grouping pattern selected from a plurality of grouping patterns, a base station having the minimum transmission power that satisfies the reception level threshold at each terminal station is selected as a base station capable of accommodating each terminal station for each group. (S41). In the process of grouping in step S2, a case where a plurality of terminal stations of a plurality of groups can be accommodated at the same time in a place where one base station is installed is allowed. This can be achieved by separately installing the corresponding base stations.

  Next, assuming an interference level based on the radio wave propagation loss in each section calculated in step S1 of FIG. 1, a radio channel having no radio interference is allocated between groups while adjusting the antenna direction of the base station (S42). Details will be described with reference to FIG. Next, it is determined whether or not the wireless channel allocation has been completed for all the groups forming the grouping pattern (S43). A selection process for thinning out the group or terminal stations within the group is performed (S44), and the process returns to step S41. For example, in a case where the terminal stations that are one terminal station in one group are thinned out, or the terminal stations with the largest number of interfering terminal stations are thinned out from the group, so that the wireless channels can be allocated to all the groups forming the grouping pattern. There is. When the wireless channel assignment is completed, the performance is improved by adjusting the output of each base station (S45), and the process ends.

FIG. 5 shows an example of wireless channel allocation for each group.
Here, an example of allocating the wireless channels of eight groups G1 to G8 forming one grouping pattern selected as the minimum number of groups in step S3 from the plurality of grouping patterns formed in step S2 in FIG. Is shown. The groups G1 to G8 do not indicate the order of the groups formed by the procedure shown in FIGS. Terminal stations accommodated in each group are indicated by “□”, and base stations are not shown. It is assumed that the maximum number of terminal stations in one group is four. Since the maximum propagation loss between the base station and the terminal station of the group G4 and the terminal station accommodated in the group G5 exceeds a specified value, the group becomes another group, and the groups G4 and G5 overlap geographically. It is in the shape.

  The base stations in each group are set to the minimum transmission power that can communicate with the terminal station that accommodates them. In this state, a radio channel having no radio interference between groups is allocated to each group without adjusting the antenna direction. Here, the wireless channel ch1 is allocated to an arbitrary group G1, and the wireless channel ch1 is sequentially allocated to the groups G3, G6, and G8 without wireless interference. Next, the radio channel ch2 is allocated to an arbitrary group G2 except the group to which the radio channel ch1 is allocated, and then the radio channel ch2 is allocated to the group G4. Next, the wireless channel ch3 is allocated to an arbitrary group G5 except the group to which the wireless channels ch1 and ch2 are allocated, and then the wireless channel ch3 is allocated to the group G7.

  Here, when the wireless channels of all the groups can be assigned within the predetermined wireless channel, the wireless channel is assigned by changing the group to which the wireless channel ch1 is assigned first. For example, the processing is restarted by allocating the wireless channel ch1 to the group G2. In the case where there are eight types of allocation patterns in which groups G1 to G8 are initially allocated as wireless channel allocation patterns, an allocation pattern that uses the smallest number of wireless channels may be selected. Alternatively, the wireless channel assignment process may be terminated when the wireless channel assignment for all the groups is successful.

  As described above, the grouping of the terminal stations (S2 in FIG. 1), the selection of one grouping pattern (S3 in FIG. 1), the base station selection of each group, and the wireless channel allocation (S4 in FIG. 1) are completed.

  In the last step S45 of the step S4, the performance is improved by adjusting the output of each base station. In step S41, a base station capable of accommodating all terminal stations in one group with as small a transmission power as possible is selected, and if the combination is determined for all groups, in step S45 a range is selected within a range that does not interfere with other groups. Adjust so that the maximum transmission power is obtained.

  In step S41, a base station capable of accommodating all terminal stations in one group with a transmission power as small as possible is selected. However, a base station that has a minimum wireless channel allocation pattern based on the base station selected by each group is selected. When there are a plurality of allocation patterns, an allocation pattern in which the minimum value of the transmission power of each group is maximum for each allocation pattern, or an allocation pattern in which the sum or the median of the minimum values of the transmission power of each group is maximum, which is predetermined Alternatively, an allocation pattern that maximizes the sum or the median of the transmission power minimum values of the group including the terminal station may be selected.

A, B, C, D, E, F terminal stations (originating terminal station, selected terminal station)
G1-G8 group

Claims (8)

A station design method for designing a set of terminal stations to be accommodated in each group and a radio channel to be assigned to each group so that a set of terminal stations that can be simultaneously accommodated by a plurality of base stations are grouped together and there is no radio interference between the groups. At
All terminal stations to be designed for station placement are grouped based on the propagation loss between the terminal stations and the presence / absence of simultaneously accommodable base stations within the maximum accommodation number M of the base stations (M is an integer of 2 or more), and Step 1 of generating a plurality of grouping patterns by changing terminal stations
Selecting one grouping pattern based on a predetermined condition from the plurality of generated grouping patterns; and
A base station capable of accommodating each terminal station is selected for each group constituting the selected grouping pattern, and a radio channel having no radio interference between groups is allocated while adjusting an antenna direction of a directional antenna of the base station. Step 3. A station design method comprising: In the station design method according to claim 1,
The step 1 is to select a starting terminal station which is a starting point of the group of the grouping pattern and has an accommodating base station, and minimizes a propagation loss between the second and subsequent selected terminal stations and an existing terminal station in the group. When there is a base station capable of accommodating the originating terminal station and the selected terminal station at the same time, the process of adding to the group is repeated until the grouping for all the terminal stations of the station design is completed to generate the grouping pattern. A station design method characterized by performing processing. In the station design method according to claim 2,
The step 1, when the group existing terminal stations are only the originating terminal station, select a terminal station having a minimum propagation loss with the originating terminal station as the second selected terminal station, When there are a plurality of terminal stations existing in the group, the propagation loss L between the i-th terminal station (i is an integer of 3 or more) and the (i-1) -th terminal station, A station design method characterized by performing a process of selecting a terminal that minimizes the sum of the maximum propagation loss R with the terminal station. In the station design method according to claim 2 or 3,
The station design method according to claim 1, wherein in the step 1, a selected terminal station whose propagation loss between the terminal stations in the group exceeds a specified value is not added to the group. In the station design method according to claim 1,
In the step 2, the predetermined condition is that the number of groups forming the grouping pattern is the minimum, or the maximum propagation loss between terminal stations in each group forming the grouping pattern is the minimum. Design method. In the station design method according to claim 1,
The station design method according to claim 3, wherein the step 3 performs a process of selecting a base station having a minimum transmission power that satisfies a reception level threshold of each terminal station as a base station capable of accommodating each terminal station for each group. . In the station design method according to claim 1,
In the step 3, when the predetermined number of radio channels cannot be satisfied with respect to the number of groups, a predetermined group or a terminal station having the largest number of interfering terminal stations in the group is thinned out and a radio channel is allocated again. Station design method. In the station design method according to claim 1,
In the step 3, when there are a plurality of radio channel allocation patterns for each group, a process of selecting an allocation pattern that minimizes the number of radio channels used in the entire grouping pattern is performed. Method.

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