JP5670856B2 - Wireless communication system and channel allocation method - Google Patents

Description

  The present invention relates to a radio communication system and a channel allocation method for performing channel allocation so that the amount of interference of the entire system is reduced for base stations of a plurality of adjacent cells in radio communication.

  In recent years, as high-speed wireless access systems using the 2.4 GHz band or the 5 GHz band, access points (base station apparatuses) based on the IEEE802.11g standard, the IEEE802.11a standard, and the like have been widely used. In systems based on these standards, an orthogonal frequency division multiplexing (OFDM) modulation scheme, which is a technology for stabilizing the characteristics in a multipath fading environment, is used, and a transmission rate of 54 Mbps is realized at the maximum. doing.

  The transmission rate here is a transmission rate on the physical layer. The effective data throughput for the user has an upper limit of about 30 Mbps because the transmission efficiency in the MAC (Medium Access Control) layer is about 50 to 70%.

  On the other hand, the communication speed of the wired LAN (Local Area Network) has been increasing due to the spread of FTTH (Fiber to the home), and in the future, further increase in the transmission speed will be required in the wireless LAN. is assumed. Various spatial signal processing techniques such as MIMO (Multiple Input Multiple Output) and multi-user MIMO are being studied to increase the throughput of the radio section. However, as another method, the communication frequency band is expanded. Yes. In IEEE802.11a, a frequency band of 20 MHz was used for each channel, but in IEEE802.11n, 40 MHz was included in IEEE802.11ac, and 160 MHz was studied when options were included, and channel band expansion was progressing. .

  As described above, the frequency band of the channel is expanded from the IEEE802.11a to 11ac by 8 times, but no significant expansion is recognized as the whole frequency band that can be used for the wireless LAN. Therefore, with the spread of wireless terminals, frequency resources are becoming insufficient, and an environment in which a plurality of wireless base stations (AP: Access point, hereinafter referred to as base stations) use the same frequency band is increasing. For this reason, depending on the channel selected by the base station, there is a problem that the throughput is lowered due to the influence of the packet signal from the overlapping base station, or the throughput efficiency of the entire system is lowered.

Next, problems of conventional frequency channel selection will be described.
FIG. 23 is a block diagram showing a configuration of a conventional radio access system. In FIG. 23, the radio access system is composed of nine base stations AP1 to AP9 located in the proximity area. Depending on the positional relationship, the amount of interference between signals differs, and here, the base stations adjacent to each other vertically and diagonally have their transmission signals observed at a level sufficiently higher than the minimum detection sensitivity. The received signals from two adjacent base stations on the upper and lower sides may be observed at a level higher than the detection sensitivity, but may be received below the minimum detection sensitivity. This indicates that the relationship affects the part throughput (dotted arrow), and signals from base stations farther than that cannot be heard from each other.

  In the base stations AP1, AP3, AP7, and AP9, there are three base stations (interference-related base stations) that are clearly audible with solid arrows, and base stations that are related with dotted arrows that may be audible. There are two weak interference base stations. In the base stations AP2, AP4, AP6, AP8, there are five interference-related base stations and one weak-interference-related base station. The base station AP5 has eight interference related base stations.

  FIG. 24 is a conceptual diagram showing channel arrangement in the radio access system. Under the conditions described in FIG. 23, the frequency channel for communication with the terminal of the own cell is selected from the channel arrangement shown in FIG. The channel arrangement of FIG. 24 shows a band that can be used in the IEEE 802.11 5 GHz band. The minimum frequency band that can be used is 20 MHz, and bands of 40 MHz, 80 MHz, and 160 MHz can be used. It is considered that each of the channels A to η shown in FIG. 24 selects a channel so as to maximize the throughput of the communication cell of the own base station. Under such conditions, each of the base stations AP1 to AP9 operates so as to use a frequency band as wide as possible, and either channel A or channel B is selected.

  Here, since it is unlikely that all the base stations AP1 to AP9 are installed at the same time, it is considered that the power is turned on one by one from the base station AP1 to the base station AP9 in order. When the base station AP1 is set up, since no frequency is used, the channel A or the channel B can be selected. Here, the channel A is selected. Next, the base station AP2 is set up and selects channel B, which is an empty channel.

  Next, when the base station AP3 is set up, since the base station AP1 has a weak interference relationship, the channel A is selected again. Up to this point, a channel to be used can be selected based on an empty channel. However, since both base stations AP4 to AP9 use both channel A and B, they have to select a channel at random. However, depending on the throughput used in the communication cells of each of the base stations AP1 to AP9 and the relationship of temporal increase / decrease in throughput, the system throughput decreases in the frequency channel A or B in which the throughput is biased. In addition, in the selection result, there is also a problem that the throughput of the base station is reduced by selecting a channel in which a plurality of base stations that operate independently and are not in the viewing range from each other as seen from a certain base station. It becomes. For example, in the example of FIG. 23, when the base stations AP1, AP5, and AP9 select channel A, the base stations AP1 and AP9 operate independently because they cannot see each other's transmission signals, but when viewed from the base station AP5 Since both base stations seem to operate without following the MAC protocols such as CSMA / CA and RTS / CTS, there is a problem that it is difficult to obtain access rights.

  Here, a wireless LAN is shown as an example. However, the same problem occurs in any system in which the number of base stations is large with respect to the frequency channels that can be used and the base stations autonomously determine the channels.

JP 2007-74097 A

  As described above, in an environment where there are not enough frequency channels available for the number of base stations that acquire frequency channels autonomously, when the frequency is selected autonomously, the carrier sense of the base station The function is a random selection, and there is a problem that the number of terminals used and the total amount of throughput are biased depending on the selected frequency channel, and the system throughput does not increase.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a radio communication system and a channel allocation method capable of increasing the throughput of a plurality of base stations as a whole.

  In order to solve the above-described problem, the present invention is a wireless communication system that allocates channels used for communication to a plurality of base station apparatuses, comprising a centralized control station connected to the plurality of base station apparatuses, and The control station collects the interference information notified from each base station apparatus, and the interference information collected by the interference information collection means, so that the amount of interference is minimized. Channel allocation determining means for determining channel allocation, and channel notification means for notifying each base station apparatus of the allocated channel determined by the channel allocation determining means. Each base station apparatus determines a channel used for communication as a channel. Channel change means for changing to the channel notified by the notification means is provided.

  The present invention also provides an interference amount increase / decrease determination in which the centralized control station evaluates whether the interference amount is reduced by changing the currently determined channel assignment to another channel for each base station apparatus. The channel allocation determination means updates the channel allocation of the base station apparatus based on the evaluation result when the interference amount increase / decrease determination means evaluates that the interference amount decreases. To do.

  Further, the present invention is configured to determine whether or not the interference amount of each channel is larger than a predetermined threshold when the central control station can divide the channel allocated to each base station device into a channel having a narrower frequency band. When the interference is determined to be greater than the threshold by the channel division determination unit and the channel division determination unit, the channel is divided into channels of a narrow frequency band, and the base station apparatus using the channel is renewed. When the channel subdivision means for redistributing the channels and the channel arrangement redistributed by the channel subdivision distribution means can be integrated into a channel with a wider frequency band, the interference amount of each channel is set to a predetermined threshold. It is determined that the interference amount is smaller than the threshold value by the channel integration determination unit and the channel integration determination unit that determine whether or not it is smaller than the threshold. The case, and integrated into the channel of the wide frequency band channels, further characterized in that it comprises a channel combination distributing means redistributing the new channels a base station apparatus has been used the channel.

  In addition, according to the present invention, the central control station changes the currently assigned channel assignment to another channel, thereby reducing the sum of the penalty determined from the frequency bandwidth being used and the amount of interference. Interference / penalty increase / decrease determining means for evaluating each base station device to determine whether the throughput index calculated from the frequency band being used and the amount of interference increases, and interference / penalty increase / decrease determining means When it is determined that the sum of the amount and the penalty is decreased, or when it is determined that the throughput index is increased, the channel change information update unit and the channel change information update unit change the channel of the base station apparatus. In a channel arrangement, subdivide channels into narrow frequency band channels, or divide multiple channels into wide Channel frequency band change determination means for determining whether the sum of the interference amount and the penalty can be reduced or whether the throughput index can be increased by integrating the channels into channels of several bands, and channel frequency band change determination means When it is determined that the sum of the interference amount and penalty can be reduced, or when it is determined that the throughput index can be increased, the channel is divided into narrow frequency band channels or multiple channels are widened. Channel frequency band changing / distributing means for redistributing the base station apparatus that used the channel into a new channel, which is integrated into the frequency band channel, is further provided.

  Further, the present invention is currently determined as interference information / terminal function collecting means for collecting interference information notified by each base station apparatus and a frequency band function of a terminal serving as a communication partner, by the central control station. By changing the channel assignment to another channel, the sum of the penalty and the amount of interference calculated from the frequency bandwidth being used and the frequency bandwidth function of the terminal with which you are communicating is reduced or used. The interference / penalty increase / decrease determining means for evaluating each base station apparatus to determine whether the throughput index calculated from the frequency band being used and the interference amount is increased, and the sum of the interference amount and penalty by the interference / penalty increase / decrease determining means. A channel changing means for changing the channel of the base station apparatus when it is determined that the throughput is decreased or the throughput index is increased. Reduces the sum of interference and penalty by subdividing channels into narrow frequency band channels or integrating multiple channels into wide frequency band channels in the channel arrangement changed by the channel changing means Channel frequency band change determining means for determining whether the throughput index can be increased and the channel frequency band change determining means determines that the sum of the interference amount and the penalty can be reduced, or When it is determined that the throughput index can be increased, the channel is divided into narrow frequency band channels, or a plurality of channels are integrated into a wide frequency band channel, and a base station device that uses the channel is newly added. Channel frequency band changing and distributing means for redistributing to different channels, and That.

  In the present invention, the channel frequency band change determination means may be configured such that, in the channel arrangement changed by the channel change means, a plurality of base station apparatuses that are not in an interference relationship with a certain base station apparatus are in an interference relationship. The channel is subdivided into narrow frequency band channels.

  In the present invention, the channel frequency band change determination means may be configured such that, in the channel arrangement changed by the channel change means, a plurality of base station apparatuses that are not in an interference relationship with a certain base station apparatus are in an interference relationship. In addition, increase the evaluation value of the interference amount of the base station device or add a new penalty, and then determine whether the sum of the interference amount and the penalty decreases, and subdivide the channel into narrow frequency band channels It is characterized by.

  The present invention further includes interference detection channel determining means for designating that the central control station uses the same channel for a plurality of base station apparatuses, and each of the plurality of base station apparatuses is provided in the central control station. Interference information measuring means for measuring interference information of communication using a designated channel, and interference information output means for notifying the central control station of interference information obtained by the interference information measuring means. Features.

Further, the present invention is a channel allocation method for allocating channels used for communication to a plurality of base station apparatuses, wherein a central control station connected to each of the plurality of base station apparatuses is notified from each base station apparatus. Interference information collecting step for collecting interference information, channel assignment determining step for determining channel assignment of each base station apparatus so that the amount of interference is minimized from the interference information collected in the interference information collecting step, the assignment channel determined by the channel allocation determining step, a channel notifying step of notifying the base station apparatuses, each base station apparatus, the channel changing step of changing the channel to be used for communication, the notified channel in the channel notification step A channel assignment method characterized by including:

  According to the present invention, the throughput of the controlled base station as a whole can be increased by controlling the frequency channel acquired by the base station by the central station.

It is a block diagram which shows the structure of the radio | wireless access system of this invention. It is a conceptual diagram which shows the result of having collected information in central control station (AC) 10 about the interference conditions between nine base stations AP1-AP9 in case # 1 of this 1st Embodiment. It is a conceptual diagram which shows an example of the interference condition between nine base stations AP1-AP9 in case # 1 of this 1st Embodiment numerically. It is a conceptual diagram for demonstrating the channel allocation by this 1st Embodiment (case # 1). It is a conceptual diagram for demonstrating the channel allocation by this 1st Embodiment (case # 1). It is a conceptual diagram for demonstrating the channel allocation by this 1st Embodiment (case # 1). It is a conceptual diagram for demonstrating the channel allocation by this 1st Embodiment (case # 1). It is a conceptual diagram which shows an example of the interference condition between nine base stations AP1-AP9 in case # 2 of this 1st Embodiment numerically. It is a conceptual diagram for demonstrating the allocation of the channel by this 1st Embodiment (case # 2). It is a conceptual diagram for demonstrating the allocation of the channel by this 1st Embodiment (case # 2). It is a conceptual diagram for demonstrating the allocation of the channel by this 1st Embodiment (case # 2). In this 2nd Embodiment, it is a conceptual diagram which shows the result made to report about the interference relation in the channel selected from each base station AP1-AP9. In this 2nd Embodiment, it is a conceptual diagram which shows the interference relationship at the time of changing base station AP4 to the channel B. FIG. It is a conceptual diagram which shows an example of a penalty in case a zone | band differs by the 3rd Embodiment. It is a conceptual diagram which shows the result of having allocated base station AP5 to the channel A in this 3rd Embodiment. In this 4th Embodiment, it is a conceptual diagram which shows the value of the penalty which considered the function of the terminal at the time of allocating base station AP1-AP9 to the channel A and the channel E. In this 5th Embodiment, it is a conceptual diagram which shows the interference relationship at the time of subdividing and assigning a channel. It is a flowchart for demonstrating the 1st method corresponding to 1st Embodiment. It is a flowchart for demonstrating the 2nd method corresponding to 2nd Embodiment. It is a flowchart for demonstrating the 3rd method corresponding to 5th Embodiment. It is a flowchart for demonstrating the 4th method corresponding to 3rd Embodiment. It is a flowchart for demonstrating the 5th method corresponding to 4th Embodiment. It is a block diagram which shows the structure of the conventional radio | wireless access system. It is a conceptual diagram which shows the channel arrangement | positioning in a radio | wireless access system.

  In wireless communication, when a plurality of wireless cells are close to each other and the number of frequency channels is small, interference occurs between the wireless cells. One technical problem in this case is to assign a frequency channel to each base station so that the amount of interference in the entire system is reduced. In the present invention, a centralized control station connected to a plurality of base stations acquires the interference situation measured in each base station, and each of the plurality of channels has a lower total sum of interference amounts in each channel. Assign a base station. In particular, assigning a base station excluding a base station with the largest amount of interference among all the base stations to one channel, and assigning to the other channel in order from the base station with the largest amount of interference. It is characterized by repeating until the standard is satisfied. With such a configuration, even in an environment where the number of channels is small with respect to the number of base stations, channel allocation that reduces the amount of interference of the entire system becomes possible.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the wireless access system of the present invention. In FIG. 1, the radio access system is composed of nine base stations AP1 to AP9 located in the close area as in the prior art, and further collects the interference status of each base station, Is provided with a central control station (AC) 10 that performs control for assigning a channel to each base station. That is, the centralized control station 10 of the present invention includes interference detection channel determination means that designates the use of the same channel for a plurality of base stations. Each of the plurality of base stations includes an interference information measuring unit that measures interference information of communication with each other using a channel designated by the central control station 10. Each of the plurality of base stations includes an interference information output unit that notifies the central control station 10 of the obtained interference information. All the base stations AP1 to AP9 are connected to the central control station 10. Hereinafter, two cases (case # 1 and case # 2) will be described as the first embodiment.

A. First embodiment A-1. Case # 1
In the first embodiment, each base station AP1 to AP9 connected to the central control station 10 reports the mutual interference status to the central control station 10, and the central control station 10 reduces interference between the base stations AP1 to AP9. Thus, a channel is allocated to each base station AP1 to AP9. In particular, in order to simultaneously acquire the interference between the base stations AP1 to AP9, all the base stations AP1 to AP9 use the same channel when collecting the interference situation.

  In the first embodiment, the central control station 10 includes interference information collection means for collecting interference information notified from the base station, and the channel of the base station so that the amount of interference is minimized from the collected interference information. Channel allocation determining means for determining the allocation of the channel, and channel notification means for notifying the determined channel to the base station. On the other hand, the base station includes channel changing means for changing the channel used for communication to the channel notified from the central control station 10.

  FIG. 2 is a conceptual diagram showing a result of collecting information by the centralized control station (AC: Access controller) 10 regarding the interference conditions between the nine base stations AP1 to AP9 in case # 1 of the first embodiment. is there. In FIG. 2, the information of the detected base stations AP1 to AP9 is indicated by ◯, and the information of the detectable base stations AP1 to AP9 is indicated by △ although the level is slightly weak. A base station with a large number of circles and triangles on the horizontal axis overlaps with communication cells of other base stations, indicating that the base station is likely to have a reduced throughput. It is also possible to determine whether or not there is an interference relationship without distinguishing between ○ and Δ.

  That is, FIG. 3A is a conceptual diagram illustrating an example in which the group of base stations AP1 to AP6 and the base stations AP7 to AP9 are independent of each other. In this way, when there are groups that do not affect each other, it is possible to evaluate frequency channel assignment independently. Further, as shown in FIG. 3 (b), even when only the base station AP7 is associated with a small number of base stations in the group of base stations AP1 to AP6, the base stations AP1 to AP6 and the base stations AP7 to AP7 AP9 can be treated as an independent group.

  From now on, as shown in FIG. 2, a description will be given of how to perform channel assignment when the base stations AP1 to AP9 do not include independent groups.

  FIGS. 4A, 4B to 7A, 7B are conceptual diagrams for explaining channel allocation according to the first embodiment (case # 1). First, when the relationship shown in FIG. 2 is obtained, looking at the base station affected by the nearest neighbor base station, the base station AP5 is applicable, and the interference-related base station (◯) is 8 Since there are a number of them, the channel is assigned to this base station AP5. In order to increase the system throughput, of the frequency channels shown in FIG. Here, it is assumed that channel B is assigned. Also assume that the remaining base stations are assigned to channel A.

  Next, it can be seen from FIGS. 4 (a) and 4 (b) that the sum of base stations AP2, AP4, AP6, AP8 having the interference relationship and the base station having the weak interference relationship is the largest (shaded portion). Indicates the interference status of the base station excluded from the channel). One of these interference relationships is excluded from channel A and assigned to channel B. Here, base station AP2 is moved to channel B. Then, the mutual relationship is updated as shown in FIGS.

  Here, the number of base stations having interference relations in channels A and B is reduced from 36 to 26 in the interference relations and weak interference relations in channel A as compared with the state shown in FIGS. 4 (a) and 4 (b). The channel B decreases from 0 to 2 in the channel B. It can be seen that the sum of the sum of the interference relationship and the weak interference relationship is remarkably improved. In FIG. 5A, it can be seen that there are four interference relationships of the base station AP8, which is the largest. Therefore, when the base station AP8 moves from channel A to channel B, the number of interference relationships and weak interference relationships decreases from 26 to 18 in channel A as shown in FIGS. 6 (a) and 6 (b). In channel B, the number increases from 2 to 6. However, it can be seen that the overall number of interference relationships has been greatly reduced. In this manner, channel assignment can be determined by minimizing the number of interference relations or weak interference relations.

  Further, consider removing a base station having more interference relation from channel A shown in FIG. Although it can be selected from those having a large sum of ○ and Δ, in channel A, since the sum of the numbers of ○ and Δ is the same, values obtained by weighting ○ and Δ can be used. . When weight is given to ○ where the signal is received at a strong level, base stations AP4 and AP6 under the condition of ○ 2 △ 1 are selected, and when weight is attached to Δ where the signal is received at a weak level, ○ 1 △ 2 Base stations AP1, AP3, AP7 and AP9 are selected.

  If the signal is strong, the communication packet is clearly received and the influence on the throughput may be larger. However, the base station with a weak signal will greatly reduce the throughput due to the effect of the hidden terminal or exposed terminal. In some cases. Here, the emphasis is placed on ○, and it is considered that either AP4 or AP6 of ○ 2Δ1 is moved to channel B. Any base station can be selected. 7A and 7B show the result of moving the base station AP4 from channel A to channel B. FIG.

  The sum of .largecircle. And .DELTA. In channel A is 11, and in channel B is 12. The sum is slightly reduced from 24 to 23. Here, as shown in FIGS. 7A and 7B, the arrangement of channel A and channel B can be determined. However, the minimum number of improved interference relations is defined, and the improvement effect is smaller than this number. If not, it can be controlled not to move the base station between channels. In the example of FIGS. 6A and 6B, assuming that the minimum improved interference relationship coefficient is 4, in FIG. 7A and FIG. In this case, the channel assignment is terminated in FIGS. 6A and 6B, and the frequency channels corresponding to the base stations AP1 to AP9 can be notified.

A-2. Case # 2
Next, Case # 2 will be described with reference to FIG.
FIG. 8 is a conceptual diagram showing numerically an example of an interference state between nine base stations AP1 to AP9 in case # 2 of the first embodiment. FIGS. 9A, 9B to 11A, 11B are conceptual diagrams for explaining channel allocation according to the first embodiment (case # 2). In FIG. 8, the numbers indicate the base stations that are in the way of the self-communication cell for the base stations described in the left column and the degree of the blockage. That is, the sum of the numbers of the column components represents the magnitude of the influence (the amount of interference) that the base station described in the top row interferes with the other base stations, and the sum of the numbers of the row components is The base station in the leftmost column indicates the magnitude of the influence (interference amount) that is disturbed.

  In the case of considering only the overlap according to FIG. 2, it is equivalent to thinking that the amount of interference and the amount of interference are the same, and it is not necessary to consider the column direction. However, in case # 2, the interference and the interference can be defined by the difference in the amount of communication data of each base station. The amount of interference is the percentage of the packet time of other base stations measured by each base station and the terminals under the base station, and the base station that sent the packet that was in the way when trying to communicate with the base station and its subordinates. Of terminals, frequency, number of terminals belonging to other base stations, and amount of data transmitted or received from the centralized control station (AC) 10 to each connected base station, or their It is an indicator that disturbs (disturbs) the communication obtained by the combination.

  For example, in the second row and first column, the numeral “15” in the cross portion between the base station AP2 and the base station AP1 represents the size at which the base station AP2 is obstructed from the base station AP1. Also, the number “10” in the cross portion between the base station AP2 and the base station AP1 in the first row and the second column represents the size at which the base station AP1 is obstructed by the base station AP2. After evaluating these indices at each base station, it can be transmitted to the central control station (AC) 10, and the central control station (AC) 10 provides information on the communication status of other base stations fed back from the base station. It can also be calculated from That is, the centralized control station (AC) 10 determines, for each base station, an interference amount increase / decrease determination unit that evaluates whether the interference amount is reduced by changing the currently determined channel assignment to another channel. Is provided. Further, the channel assignment determining unit of the centralized control station (AC) 10 updates the channel assignment of the base station apparatus based on the evaluation result when the interference amount increase / decrease determining unit evaluates that the interference amount decreases.

  From FIG. 8, it can be seen from the bottom row of the table that when all the base stations AP1 to AP9 are set to the same frequency channel, the base station AP4 is the most obstructing communication with the other base stations. Therefore, the base station AP4 and other base stations are assigned to the channel B and the channel A, respectively, as shown in FIGS. 9 (a) and 9 (b). In this way, since the base station AP4 that most affected the communication is deleted from FIG. 9A, the sum of the interference amounts described in the rightmost column is the base station AP4 in FIG. It can be seen that there is a decrease by the sum (424) of the sum of the amount of interference (320) and the sum of the interfered (104) received by the base station AP4.

  9A and 9B, since the interference amount and the number of APs are unbalanced between channel A and channel B, a base station to be assigned from channel A to channel B is further selected. As a guideline for selection, an interference amount generated by allocating to channel B is selected to be smaller than a decrease amount of the interference amount obtained by removing the base station from channel A. Here, it can be seen that the base stations that do not interfere with each other with the base station AP4 are the base station AP3 and the base station AP9. Therefore, the base station AP3 and the base station AP9 can be assigned to the channel B as shown in FIGS. 9A, the sum of the interference amounts of channel A is 676 (= 39 + 97 + 45 + 157 + 121 + 67 + 51 + 99), but it is greatly reduced to 357 (= 24 + 52 + 105 + 69 + 63 + 44) in FIG. 10A. On the other hand, although the sum of the interference amount of channel B slightly increases from 0 to 23, it is much smaller than the improvement amount of channel A.

  Furthermore, the centralized control station (AC) 10 considers whether there is a base station to change from channel A to channel B. For the base stations AP1, AP2, AP5, AP6, AP7, AP8, the amount of interference obtained by removing from the channel A is the sum of the amount of interference shown in the bottom row and the amount of interference in the rightmost column. 34 + 24 = 58, 35 + 52 = 87, 45 + 105 = 160, 54 + 69 = 123, 29 + 63 = 92, 160 + 44 = 204. The amount of interference that increases by adding to channel B is obtained by taking the sum of the amount of interference in the column direction and the row direction of the area indicated by the oblique lines corresponding to the selected base station, and the base station AP1 has 20 + 75 = 95, the base station AP2 is 20 + 105 = 125, the base station AP5 is 27 + 112 = 139, the base station AP6 is 46 + 72 = 118, the base station AP7 is 14 + 64 = 78, and the base station AP8 is 100 + 67 = 167. That is, the reduction amount of the interference amount obtained by the former minus the latter is −37, −38, 21, 5, 14, and 37, respectively, and it can be seen that the effect obtained by adding the base station AP8 to the channel B is large. .

  FIGS. 11A and 11B are conceptual diagrams showing an interference relationship obtained by adding the base station AP8 to the channel B. FIG. Further, it is verified whether there is a base station to change from channel A to channel B. The amount of decrease in the interference amount due to removal from channel A of the base stations AP1, AP2, AP5, AP6, AP7 is 34 + 24 = 58, 30 + 42 = 72, 36 + 55 = 91, 36 + 19 = 55, 17 + 13 = 30. Further, the amount of increase in interference due to addition to channel B is 20 + 75 = 95, 25 + 115 = 140, 36 + 162 = 198, 64 + 122 = 186, 26 + 114 = 140.

  The reduction effect of the interference amount is −37, −68, −107, −131, −110, and it can be seen that the interference amount increases regardless of the movement, and the channels shown in FIGS. The allocation can be notified to each of the base stations AP1 to AP9, and channel assignment can be determined.

  Or, as the evaluation value of the interference amount so far, the sum of the interference amount and the interference amount is used as an index. However, the channel allocation may be determined using either the interference amount or the interference amount. it can.

  In addition, if a minimum consideration value of the interference amount improvement effect is defined in advance and the interference amount is not improved to be larger than this value, the channel assignment may not be changed. For example, when the minimum consideration value is set to 40 here, the amount of improvement 38 of the interference amount when the base station AP8 is moved from channel A to channel B in FIGS. It is not sufficient, and the channel assignments shown in FIGS. 10A and 10B can be notified to each base station.

B. Second Embodiment Next, a second embodiment of the present invention will be described.
In the first embodiment described above, the base stations AP1 to AP9 acquire the interference status of each other using the same channel. On the other hand, in this 2nd Embodiment, it exists in acquiring the interference condition in the channel currently used by each base station AP1-AP9. That is, the base stations AP1 to AP9 determine channels to be used independently as basic operations, and report interference conditions in the determined channels to the centralized control station (AC) 10. Alternatively, after channel assignment is performed in the first embodiment, operation is performed using only the assigned channel, and a state in which an interference relationship of only the assigned channel is clarified is made to correspond.

  FIGS. 12A and 12B are conceptual diagrams illustrating the results of reporting the interference relationship in the channels selected from the base stations AP1 to AP9 in the second embodiment. 12 (a) and 12 (b) show a state in which the base stations AP1, AP3, AP4, AP6, AP7, AP8 have selected channel A, and the base stations AP2, AP5, AP9 have selected channel B. The result of having reported the interference relation in the channel selected from AP1-AP9 is shown. Unlike case # 1, the table is not completely filled because it can only report interference conditions on the same channel. Even in the case # 2, the channel change of the base station can be set so that the amount of interference becomes small as in the case # 1.

  12A and 12B, when the interference amount of each base station in channel A and channel B (the sum of the interference amount and the interference amount) is seen, the interference amount of the base station AP4 is the largest (200 + 87 = 287). For this reason, the base station AP4 can be changed to the channel B. The difference from Case # 1 is that it is difficult to evaluate the amount of interference that increases in channel B by changing base station AP4 to channel B. After the base station AP4 is changed to the channel B, the increase in the interference amount of the channel B is evaluated. When the throughput decrease due to the increase in the interference of the channel B is larger than the decrease in the interference amount in the channel A, the base station AP4 is It can also be returned to channel A.

  Alternatively, when the base station AP4 decides to change from channel A to channel B, the central control station (AC) 10 can cause the base station AP4 to investigate the interference condition when moving to channel B. In this case, the subordinate terminal is not notified that the channel is changed, and the base station AP4 widens the reception bandwidth or notifies the communication cell that transmission is prohibited (NAV: Network Allocation Vector). It is also possible to measure interference of other channels. In this way, by measuring the interference condition of channel B, the amount of interference when moving to channel B in advance can be measured. By changing to channel B, it is evaluated whether the amount of interference will be small, and if the amount of interference is small, it can be changed to channel B. After the change, since the information on the amount of interference is obtained from a base station other than the base station AP4 that uses channel B, the sum of the amount of interference and the amount of interference is compared with the decrease in the amount of interference in channel A. The base station AP4 can be returned to the channel A when the throughput decrease due to the increase in interference is large.

  FIGS. 13A and 13B are conceptual diagrams showing an interference relationship when the base station AP4 is changed to the channel B. FIG. The interference amount index is decreased by 287 when the base station AP4 is removed from the channel A, and is increased by 139 when the base station AP4 is added to the channel B, indicating that the interference amount index of the entire system can be decreased by 148. ing. Furthermore, as to whether to change another base station from channel A to channel B or from channel B to channel A, only the amount of interference of a specific priority base station should be considered, or Data bits exchanged between the central control station (AC) 10 and the base station in each channel using the difference in the number of stations, the difference in the number of base stations per unit frequency belonging to the channel It can be evaluated using the difference in quantity.

C. Third Embodiment Next, a third embodiment of the present invention will be described.
In the third embodiment, a case where there is a difference between the respective channels will be described. That is, when the frequency bands of the two channels are different, for example, when considering the allocation of a base station between channel A and channel E, considering the decrease in throughput due to the narrow band of channel E, the channel widening A penalty is added accordingly.

  That is, the central control station 10 according to the third embodiment changes the allocation of the currently determined channel to another channel, so that the sum of the penalty determined from the frequency bandwidth being used and the interference amount is summed. Interference / penalty increase / decrease judging means for evaluating each base station apparatus to reduce whether or not the throughput index calculated from the frequency band being used and the amount of interference increases. In addition, the central control station 10 includes channel changing means for changing the channel of the base station when it is determined that the sum of the interference amount and the penalty is reduced or when it is determined that the throughput index is increased.

  Further, the centralized control station 10 subdivides channels into narrow frequency band channels or integrates a plurality of channels into wide frequency band channels in the determined channel arrangement, thereby reducing interference amount and penalty. Channel frequency band change determination means for determining whether the sum of the two can be reduced or whether the throughput index can be increased. Further, when it is determined that the sum of the interference amount and the penalty can be reduced, or when it is determined that the throughput index can be increased, the centralized control station 10 divides the channel into narrow frequency band channels. Alternatively, a channel frequency band changing / distributing unit that integrates the plurality of channels into a wide frequency band channel and redistributes base stations that have used the channel to new channels is provided.

  FIGS. 14A and 14B are conceptual diagrams illustrating an example of a penalty when the bands are different according to the third embodiment. Since channel E is a half band of channel A, a penalty of “100” is added to the amount of interference of channel E in order to consider channel allocation. Under this condition, the sum of the amount of interference, the amount of interference, and the penalty for channel A and channel E is the largest at base station AP4, which is 120 + 19 + 100 = 239, and base station AP4 is changed to channel A. It can also be assigned. Alternatively, when the base station AP4 has originally moved from the channel A, the amount of interference and the amount of interference when the base station AP4 is assigned to the channel A are known. For this reason, when the base station AP4 is assigned to the channel A, the amount of interference and the amount of interference increase by 148. Therefore, even if the penalty is taken into consideration, the effect of assigning to the channel A is low, and it is not possible to assign this.

  Alternatively, channel assignment can be changed based on the sum of the amount of interference and the penalty. In FIG. 14B, since the sum of the interference amount and the penalty is the largest in the base station AP5 (177), it can be moved to the channel A.

  FIGS. 15A and 15B are conceptual diagrams showing the results of allocating the base station AP5 to the channel A in the third embodiment. By removing the base station AP5 from the channel E, the interference amount + penalty can be reduced by 27 + 77 + 100 = 204, and by adding it to the channel A, the sum of the interference amount and the penalty increases by 185. It can be seen that the sum of the penalty and the penalty was reduced by 19. In this way, channel allocation to the base station can be determined in consideration of the difference in bandwidth.

Alternatively, the throughput can be evaluated using the bandwidth of the channel to be used, the number of OFDM subcarriers that can be used, and interference information on the channel. If the bandwidth of the channel under consideration or the number of usable OFDM subcarriers is B, the throughput evaluation value T _i of the j-th base station can be calculated as the following equation (1).

  ε is an indicator of the amount of interference in the channel under consideration, and the number of interference relations may be used, or the amount of interference, the amount of interference, the sum thereof, etc. as shown in FIG. 8 may be used. . f (ε) is a function of ε, and is set to take a smaller value as the interference condition is larger. An index of throughput calculated in this way is calculated at each base station, and the channel of the base station can be determined so as to maximize this sum.

D. Fourth Embodiment Next, a fourth embodiment of the present invention will be described.
In the present fourth embodiment, the penalty given as interference in the third embodiment is given according to the capabilities of the terminals under the control of the base station and the allocated bandwidth. That is, the centralized control station 10 of the fourth embodiment includes interference information / terminal function collection means for collecting interference information notified by each base station and the frequency band function of a terminal that is a communication partner. Further, the central control station 10 changes the currently assigned channel assignment to another channel, thereby calculating the penalty calculated from the frequency bandwidth being used and the frequency band function of the terminal serving as the communication partner. There is provided an interference / penalty increase / decrease judging means for evaluating each base station whether the sum with the interference amount is reduced or whether the throughput index calculated from the frequency band being used and the interference amount is increased.

  In addition, the central control station 10 includes channel changing means for changing the channel of the base station when it is determined that the sum of the interference amount and the penalty is reduced or when it is determined that the throughput index is increased. Further, the centralized control station 10 subdivides channels into narrow frequency band channels in a changed channel arrangement, or integrates a plurality of channels into wide frequency band channels, thereby reducing interference amount and penalty. Channel frequency band change determination means for determining whether the sum of the two can be reduced or whether the throughput index can be increased.

  Further, when it is determined that the sum of the interference amount and the penalty can be reduced, or when it is determined that the throughput index can be increased, the centralized control station 10 moves the channel to a narrow frequency band. Channel frequency band changing / distributing means is provided that divides the channel into channels or integrates the plurality of channels into a wide frequency band channel and redistributes base stations that have used the channel to new channels.

  For example, in the channel assignment shown in FIG. 24, even if a 160 MHz band is assigned, if the terminal under the base station supports only up to 40 MHz, the communication cell can only use up to 40 MHz. Therefore, for example, when the penalty size is 0 at 160 MHz, 100 at 80 MHz, 200 at 40 MHz, and 400 at 20 MHz, if the terminal under the base station supports up to 40 MHz, the allocated bandwidth is 80 MHz to Even at 160 MHz, the penalty can be set to 200. Also, the penalty value can be flexibly set according to the ratio of the functions of the terminals under the base station.

  At this time, each base station notifies the central control station (AC) 10 of the function information of the frequency bands of the terminals under its control. For example, if there are four terminals under the control of the base station AP2 and each supports 20 MHz, 40 MHz, 80 MHz, and 160 MHz, the penalty when assigning these terminals to a 160 MHz channel is the average of the obtained penalties (400 + 200 + 100 ) / 4 = 175. At this time, when assigning to an 80 MHz channel, a terminal that supports 160 MHz also uses 80 MHz, so the penalty is (400 + 200 + 100 + 100) / 4 = 200.

Alternatively, a penalty can be given according to the communication frequency. For example, if the communication frequency is 0.2, 0.5, 0.1, and 0.2 for terminals supporting 20 MHz to 160 MHz, respectively, the penalty for assigning to a 160 MHz channel is (400 × 0. 2 + 200 × 0.5 + 100 × 0.1 + 0 × 0.2) = 190. Here, the penalty when allocating to the 80 MHz channel is (400 × 0.2 + 200 × 0.5 + 100 × 0.1 + 100 × 0.2) = 210. Assume that there are U terminals under control, the penalty determined by the frequency band function of each terminal _{1 to U} is defined as X _{1 to} X _U , the weighting coefficient determined from the communication frequency is ρ ₁ to ρ _U, and assigned If a penalty determined by the obtained frequency band to X _W, penalty Z of the base station for allocating to the frequency band can be expressed by the following equation (2).

FIGS. 16A and 16B are conceptual diagrams showing penalty values in consideration of the function of the terminal when the base stations AP1 to AP9 are assigned to the channel A and the channel E in the fourth embodiment. The penalty is the result of calculating ρ _i as 1 / U in Equation (1). The base station AP1 communicates with a 20 MHz terminal and an 80 MHz terminal, the base station AP2 is a 40 MHz terminal, the base station AP3 is an 80 MHz terminal, the base station AP4 is an 80 MHz and 160 MHz terminal, and the base station AP5 is 160 MHz. The base station AP6 communicates with 160 MHz terminals and 80 MHz terminals, the base station AP7 communicates with 160 MHz terminals, the base station AP8 communicates with 40 MHz terminals, and the base station AP9 communicates with 160 MHz, 80 MHz, and 40 MHz terminals.

  Therefore, the penalty of the base stations AP1 to AP9 is (400 + 100) / 2 = 250, Max (200, 100) = 200, 100, (Max (0, 100) + Max (100, 100)) / 2 = 100, 0 , (0 + 100) / 2 = 50, 0, 200, (Max (0, 100) + Max (100, 100) + Max (200, 100)) = 150. The sum of the penalty of channel A and the amount of interference can be expressed as 362 + 600 = 962.

  Alternatively, the same evaluation can be performed by calculating B in Expression (1) in consideration of the function of the terminal with which the base station communicates. B in the equation (1) can be calculated as the following equation (3).

B _i is the frequency bandwidth or the number of frequency subcarriers that can be used in the function of the i-th terminal with which the j-th base station is communicating, and ρ _{1 to} ρ _U are the same as in Equation (2) It is a weighting coefficient determined from the frequency. By calculating the throughput index in this way, it is possible to evaluate channel assignment including the function of the terminal with which the base station is communicating.

E. Fifth Embodiment Next, a fifth embodiment according to the present invention will be described.
The fifth embodiment is characterized in that, in the fourth embodiment, channels are subdivided and allocated. That is, the central control station 10 according to the fifth embodiment determines whether the interference amount of each channel is larger than a predetermined threshold when the channel assigned to the base station can be divided into channels with narrower frequency bands. A channel division determination means for determining whether or not. Further, when it is determined that the amount of interference is larger than the threshold value, the central control station 10 divides the channel into channels of a narrow frequency band, and redistributes base stations using the channel to new channels. Subdividing means are provided.

  The central control station 10 determines whether or not the interference amount of each channel is smaller than a predetermined threshold when the redistributed channel arrangement can be integrated into a channel with a wider frequency band. A determination unit is provided. Further, when it is determined that the amount of interference is smaller than the threshold, the centralized control station 10 integrates the channel into a channel having a wide frequency band, and redistributes the base station apparatus using the channel to a new channel. A channel integrated distribution means is provided.

For example, consider that channel A is divided into 80 MHz channels and channel C and channel D are used. At this time, since the frequency band is halved, the _{X w} of the equation (2), from 0 to channel A, increased to 100. That is, the penalties for the frequency bands of the base stations AP1, AP3, AP5, AP6, AP7, AP8 are (Max (400, 100) + Max (100, 100)) / 2 = 250, Max (100, 100) = 100, Max (0, 100) = 100, (Max (0, 100) + Max (100, 100)) / 2 = 100, Max (0, 100) = 100, Max (200, 100) = 100, penalty Increases by 250 in total.

  Next, consider the amount of interference between base stations. Similar to the above process, channel A base stations are assigned to channel C and channel D. As a result of allocating the base station AP8 having the largest amount of interference to channel C and the other base stations to channel D and assigning the total amount of interference to the minimum, the base stations AP1, AP3 and AP8 are assigned to the channel. C, base stations AP4, AP5, AP6 are assigned to channel D.

  FIGS. 17A and 17B are conceptual diagrams showing an interference relationship when the above-described channel is subdivided and assigned to channel C and channel D in the fifth embodiment. 17A and 17B, the sum of the interference amount and the penalty is 68 + 850 = 918. From the results of FIGS. 16A and 16B, the index of the sum is lowered by 44. ing. In this way, it is possible to set a penalty and determine an appropriate channel assignment by using information on the band of the channel to be used and the performance of the terminal.

  Alternatively, when dividing a channel into finer frequency bands, it is possible to use only the improvement of the penalty, or to divide when the sum of the interference amounts is larger than a certain value.

  Further, after using the subdivided channel, it is determined whether the data transmission amount from the centralized control station (AC) 10 to the AP of the subdivided channel has decreased, or the decrease in the interference amount is determined. Thus, it is possible to determine whether to return to the original large channel before the segmentation.

F. Sixth Embodiment Next, a sixth embodiment of the present invention will be described.
In the sixth embodiment, in the first to fourth embodiments, a situation in which a base station receives signals of a plurality of base stations that operate independently is prohibited, or a plurality of base stations that operate independently A penalty is added to the situation where a certain base station receives the above signal. Here, the base station that operates independently refers to a base station that cannot receive each other's transmission signals and performs communication based on CSMA / CA or RTS / CTS independently.

  That is, the centralized control station 10 according to the sixth embodiment uses a narrow channel frequency when a plurality of base station apparatuses that are not in an interference relationship with a certain base station apparatus are in an interference relationship with the changed channel arrangement. A channel frequency band change determination means for subdividing into band channels is provided.

  An example in which the conditions of the sixth embodiment are considered for the channel determined in each embodiment will be described. In FIG. 7B, it can be seen that base stations using channel B are present in the receivable areas, and there is no symbol “-” indicating a state of no interference relationship. In FIG. 7B, there is no base station that operates independently. However, in FIG. 7A, there are many “-” s that are not in an interference relationship with each other. When viewed from the base station AP1, the base stations AP3 and AP7 are in an interference relationship, but the base stations AP3 and AP7 are not in an interference relationship with each other. Thus, when a plurality of base stations that are not in an interference relationship are included in the base stations that are in an interference relationship when viewed from a certain base station, it can be said that the environment is such that signals from base stations that operate independently are received. Therefore, in the sixth embodiment, the channel shown in FIG. 7A is further subdivided, and channel assignment is determined so as not to receive a plurality of base station signals operating independently of each other. Here, it can be divided into group G1 of base stations AP1 and AP7 and group G2 of base stations AP3, AP6 and AP9, and different channels, for example, channel C and channel D obtained by subdividing channel A can be assigned.

  Next, in the example of FIG. 13, both of FIG. 13A and FIG. 13B have a large number of conditions “−” that are not in an interference relationship. In FIG. 13A, the base stations AP3 and AP7 operating independently of each other are in an interference relationship. Therefore, the channel A can be divided into a group G1 composed of the base station AP1, a group G2 composed of the base stations AP3 and AP6, and a group G3 composed of the base stations AP7 and AP8, and the respective channels can be allocated. In channel B, the base station AP5 includes a base station AP9 that operates independently of the base stations AP2 and AP4 (not in an interference relationship with each other). Therefore, by separating the base stations AP2 and AP4 as the group G1 and the base stations AP5 and AP9 as the group G2, it is possible to select a plurality of base stations that operate independently.

  In FIG. 16A, there are a large number of base stations that operate independently. For example, the base station AP1 has base stations AP3 and AP7 that operate independently, and the base station AP2 has base stations AP1 and AP6 that operate independently. including. Channel division can be performed so that base stations that operate independently are not included in the interference relationship, and the sum of interference, interference, and penalty is minimized.

  Further, in the sixth embodiment, when a plurality of base station apparatuses that are not in an interference relationship with a certain base station apparatus have an interference relationship with the changed channel arrangement, the interference amount of the base station apparatus is evaluated. A channel frequency band change determining unit is provided for determining whether the sum of the interference amount and the penalty decreases after increasing the value or adding a new penalty, and subdividing the channel into channels of a narrow frequency band.

  Therefore, when there is a base station that operates independently, a new penalty can be added. For example, in the example of FIG. 16A, a penalty of the number of independently operating base stations × 50 may be newly added, or an independent operating base station may be evaluated by multiplying the amount of interference by H times. it can. If H is 2, the amount of interference in FIG. 16A can be doubled, and channel subdivision can be evaluated as in the fourth embodiment.

G. Operation of Each Embodiment The operation of the first to fifth embodiments described above will be described with reference to FIGS.

G-1. Operation of First Embodiment FIG. 18 is a flowchart for explaining a first method corresponding to the first embodiment. In the first method, the centralized control station (AC) 10 collects interference information from the connected base stations AP1 to AP9, and obtains an interference relationship table as shown in FIG. 2 or FIG. 8 (step S101). ). From the obtained interference relationship table, each base station AP1 to AP9 can minimize the amount of interference (number of circles and triangles in FIG. 2, the amount of interference in FIG. 8, and the sum of interference amounts). The channels to be used are determined (step S102), and their allocation is notified to the base stations AP1 to AP9 (step S103). When notified of the channel, the base stations AP1 to AP9 switch to the designated channel and communicate with the communication partner terminal (step S104).

G-2. Operation of Second Embodiment FIG. 19 is a flowchart for explaining a second method corresponding to the second embodiment. In the second method, the centralized control station (AC) 10 collects interference information from the connected base stations AP1 to AP9, and FIG. 2, FIG. 3 (a), (b) to FIG. b), FIG. 8, FIG. 9 (a), (b)-FIG. 17 (a), the table of interference relationship as obtained in (b) is acquired (step S201). From the obtained interference relationship table, it is determined whether the amount of interference is reduced by assigning the channels currently assigned to the base stations AP1 to AP9 to other channels (step S202). If the amount of interference decreases (YES in step S202), the change of channel information of the base station is notified (step S203), and the base station changes the channel to be used (step S204).

  The current channel used in each base station AP1 to AP9 can be notified from each base station AP1 to AP9, or the channel designated by the centralized control station (AC) 10 can be stored. . In this way, FIGS. 4 (a) and (b) to FIGS. 5 (a) and 5 (b), FIGS. 5 (a) and 5 (b) to FIGS. 6 (a), 6 (b), and 6 (a). , (B) to FIG. 7 (a), (b), FIG. 9 (a), (b) to FIG. 10 (a), (b), FIG. 10 (a), (b) to FIG. , (B), and FIGS. 12 (a) and 12 (b), the channel assignment can be changed as shown in FIGS. 13 (a) and 13 (b).

G-3. Operation of Fifth Embodiment FIG. 20 is a flowchart for explaining a third method corresponding to the fifth embodiment. In the third method, the central control station (AC) 10 collects interference information from the connected base stations AP1 to AP9, and FIG. 2, FIG. 3 (a), (b) to FIG. 7 (a), ( b), FIG. 8, FIG. 9 (a), (b)-FIG. 17 (a), the table of interference relationship as obtained in (b) is acquired (step S301). From the obtained interference relationship table, it is determined whether or not the amount of interference decreases by assigning the channels currently assigned to the base stations AP1 to AP9 to other channels (step S302).

  If the amount of interference decreases (YES in step S302), the channel information of the base station is changed (step S303). Next, when channel assignment is determined, it is determined whether or not there is a channel whose amount of interference exceeds a predetermined threshold and can be subdivided (step S304). If there is a channel that satisfies the condition (YES in step S304), the channel is divided into a plurality of channels having a narrow frequency band, and the interference amount is reduced to the plurality of channels having a narrow frequency band that have been assigned to the channel. Redistribute so as to be (step S305).

  Further, it is determined whether or not the sum of interference amounts is smaller than a predetermined threshold in a plurality of channels that can be broadened by combining them (step S306). If there is a channel that can be integrated smaller than the threshold (YES in step S306), the channel is changed to a channel having a wide frequency band (step S307).

  And the channel changed by said step S303, S305, S307 is notified to a corresponding base station (step S308), and the said base station changes to the designated channel (step S309). In this way, in the state of channel A shown in FIG. 15A, the sum (362) of the amount of interference is larger than the threshold value 300, so that the channel C and the channel D are divided as shown in FIG. You can also

G-4. Operation of Third Embodiment FIG. 21 is a flowchart for explaining a fourth method corresponding to the third embodiment. In the fourth method, the centralized control station (AC) 10 collects interference information from the connected base stations AP1 to AP9, and FIG. 2, FIG. 3 (a), (b) to FIG. b), FIG. 8, FIG. 9 (a), (b)-FIG. 17 (a), the table of interference relationship as obtained in (b) is acquired (step S401). The central control station (AC) 10 determines the penalty amount of each channel from the bandwidth of the channel used by the base stations AP1 to AP9, and is determined from the obtained interference relationship table and the bandwidth of each channel. It is determined whether or not the sum of the interference amount and the penalty is reduced by assigning the channel currently assigned to each of the base stations AP1 to AP9 to another channel from the magnitude of the penalty (step) S402).

  When the sum of the interference amount and the penalty decreases (YES in step S402), the channel of the base station is changed (step S403). Next, when channel allocation is determined, each channel is changed to a channel with a narrow frequency band, or a plurality of channels are integrated into one large channel, so that the sum of the interference amount and the penalty is reduced. It is determined whether or not to decrease (step S404).

  If there is a channel that satisfies the condition (YES in step S404), the channel is divided into a plurality of channels having a narrow frequency band, and the base station assigned to the channel is allocated to the plurality of channels having a narrow frequency band. Or, integrate multiple channels into a wide frequency band channel, assign base stations assigned to the multiple channels to wide frequency band channels, and redistribute them so that the sum of interference and penalty is reduced. (Step S405).

  The central control station (AC) 10 notifies the corresponding base station of the channel reallocated to the base station of the channel (step S406), and the base station of the channel changes to the designated channel (step S406). S407). In this way, it is possible to consider the allocation of base stations between channels having different frequency bandwidths as shown in FIGS. 14 (a) and 14 (b) to FIGS. 15 (a) and 15 (b).

G-5. Operation of Fourth Embodiment FIG. 22 is a flowchart for explaining a fifth method corresponding to the fourth embodiment. In the fifth method, the central control station (AC) 10 collects interference information from the connected base stations AP1 to AP9, and FIG. 2, FIG. 3 (a), (b) to FIG. b), FIG. 8, FIG. 9 (a), (b)-FIG. 17 (a), the table of interference relationship as obtained in (b) is acquired (step S501). The centralized base station (AC) 10 determines each of the base stations AP1 to AP1 from the function information of the bandwidth of the channel used by the base stations AP1 to AP9 and the frequency bandwidth of the terminal with which the base stations AP1 to AP9 are communicating. The penalty amount of AP9 is calculated (step S502).

  Next, the channel currently allocated to each base station AP1 to AP9 is changed to another channel from the obtained interference relationship table and terminal bandwidth information on which communication is performed for each base station AP1 to AP9. The amount of interference and the penalty due to the allocation are calculated, and it is determined whether or not the sum of the amount of interference and the penalty decreases (step S503). If the sum of the interference amount and the penalty decreases (YES in step S503), the channel of the base station is changed (step S504).

  Next, when the channel assignment is determined, each channel is changed to a channel having a narrow frequency band, or a plurality of channels are integrated into one large channel, so that interference between the base stations AP1 to AP9 can be achieved. The amount and the penalty amount are calculated, and it is determined whether or not the sum of the interference amount and the penalty decreases (step S505). If there is a channel satisfying the condition (YES in step S505), whether the channel is divided into a plurality of channels having a narrow frequency band, and whether the base station assigned to the channel is allocated to a plurality of channels having a narrow frequency band. Or, integrate multiple channels into a wide frequency band channel, assign base stations assigned to the multiple channels to wide frequency band channels, and redistribute so that the sum of interference amount and penalty is small (Step S506).

  The centralized control station (AC) 10 notifies the corresponding base station of the channel reassigned to the base station of the channel (step S507), and the base station of the channel changes to the designated channel (step S508). ). In this way, it is possible to consider the allocation of base stations between channels having different frequency bandwidths as shown in FIGS. 14 (a) and 14 (b) to FIGS. 15 (a) and 15 (b).

  According to the first to fifth embodiments described above, in the central control station (AC) 10 that controls the frequency channels of a plurality of base stations, the frequency channel to be used by the base station is determined from the interference conditions, and the system throughput is increased. Can be achieved.

10 Central control station (AC)
AP1 to AP9 base station

Claims (11)

A wireless communication system that assigns channels used for communication to a plurality of base station devices,
A centralized control station connected to the plurality of base station devices;
The central control station is
Interference information collecting means for collecting interference information notified from each of the base station devices;
Channel assignment determining means for determining channel assignment of each base station apparatus so that the amount of interference is minimized based on the interference information collected by the interference information collecting means;
Channel notification means for notifying each base station apparatus of the channel determined by the channel allocation determination means,
Each of the base station devices
Channel change means for changing a channel used for communication to the channel notified by the channel notification means ,
The central control station
The base station apparatus further comprises an interference amount increase / decrease determination means for evaluating whether the interference amount is reduced by changing the channel assignment currently determined to another channel,
The channel allocation determining means, a radio communication system and updates the allocation of channels in the base station device based on the if the interference amount by the interference amount change determining device evaluates to decrease, the evaluation results. A wireless communication system that assigns channels used for communication to a plurality of base station devices,
A centralized control station connected to the plurality of base station devices;
The central control station is
Interference information collecting means for collecting interference information notified from each of the base station devices;
Channel assignment determining means for determining channel assignment of each base station apparatus so that the amount of interference is minimized based on the interference information collected by the interference information collecting means;
Channel notification means for notifying each base station apparatus of the channel determined by the channel allocation determination means;
With
Each of the base station devices
Channel change means for changing a channel used for communication to the channel notified by the channel notification means,
The central control station is
Channel division determination means for determining whether or not the amount of interference of each channel is greater than a predetermined threshold when the channel allocated to each base station device can be divided into channels with narrower frequency bands;
Channel subdivision that divides the channel into narrow frequency band channels and redistributes the base station apparatus using the channel to new channels when the channel division determination unit determines that the interference amount is larger than the threshold. Distribution means,
Channel integration determination for determining whether or not the interference amount of each channel is smaller than a predetermined threshold when the channel arrangement redistributed by the channel subdivision distribution unit can be integrated into a channel having a wider frequency band. Means,
Channel integration that integrates the channel into a wide frequency band channel and redistributes the base station apparatus using the channel to a new channel when the channel integration determining unit determines that the interference amount is smaller than the threshold value radio communications system that further comprising a dispensing means. A wireless communication system that assigns channels used for communication to a plurality of base station devices,
A centralized control station connected to the plurality of base station devices;
The central control station is
Interference information collecting means for collecting interference information notified from each of the base station devices;
Channel assignment determining means for determining channel assignment of each base station apparatus so that the amount of interference is minimized based on the interference information collected by the interference information collecting means;
Channel notification means for notifying each base station apparatus of the channel determined by the channel allocation determination means;
With
Each of the base station devices
Channel change means for changing a channel used for communication to the channel notified by the channel notification means,
The central control station is
By changing the currently determined channel assignment to another channel, the sum of the penalty determined from the frequency bandwidth being used and the amount of interference is reduced, or the frequency band being used Interference / penalty increase / decrease judging means for evaluating each base station device to determine whether the throughput index calculated from the interference amount increases,
Channel change means for changing the channel of the base station device when it is determined by the interference / penalty increase / decrease determination means that the sum of the interference amount and the penalty is reduced, or when it is determined that the throughput index is increased,
In the channel arrangement determined by the channel changing means, the channel is subdivided into narrow frequency band channels, or a plurality of channels are integrated into a wide frequency band channel to reduce the sum of interference amount and penalty. A channel frequency band change determination means for determining whether or not a reduction is possible or whether or not a throughput index can be increased;
When it is determined by the channel frequency band change determination means that the sum of the interference amount and penalty can be reduced, or when it is determined that the throughput index can be increased, the channel is divided into narrow frequency band channels. or, by integrating the plurality of channels to the channel of a wide frequency band, it further comprising a channel frequency band changing distribution means for redistributing the new channels a base station apparatus has been used the channel radio communications system. A wireless communication system that assigns channels used for communication to a plurality of base station devices,
A centralized control station connected to the plurality of base station devices;
The central control station is
Interference information collecting means for collecting interference information notified from each of the base station devices;
Channel assignment determining means for determining channel assignment of each base station apparatus so that the amount of interference is minimized based on the interference information collected by the interference information collecting means;
Channel notification means for notifying each base station apparatus of the channel determined by the channel allocation determination means;
With
Each of the base station devices
Channel change means for changing a channel used for communication to the channel notified by the channel notification means,
The central control station is
The interference information / terminal function collection means for collecting the interference information notified by each of the base station devices and the frequency band function of the terminal serving as a communication partner;
Changing the currently assigned channel assignment to another channel reduces the sum of the penalty and the amount of interference calculated from the frequency bandwidth being used and the frequency bandwidth function of the terminal with which you are communicating. Or an interference / penalty increase / decrease judging means for evaluating each base station device to determine whether the throughput index calculated from the frequency band being used and the amount of interference increases,
Channel change means for changing the channel of the base station device when it is determined by the interference / penalty increase / decrease determination means that the sum of the interference amount and the penalty is reduced, or when it is determined that the throughput index is increased,
In the channel arrangement changed by the channel changing unit, the channel is subdivided into narrow frequency band channels, or a plurality of channels are integrated into a wide frequency band channel to reduce the sum of interference amount and penalty. A channel frequency band change determination means for determining whether or not the index of throughput can be reduced or increased,
When the channel frequency band change determining means determines that the sum of the interference amount and the penalty can be reduced, or when it is determined that the throughput index can be increased, the channel is changed to a narrow frequency band. A channel frequency band changing / distributing unit that divides the channel into channels or integrates the plurality of channels into a wide frequency band channel and redistributes the base station apparatus using the channel to a new channel. radio communications system shall be the. The channel frequency band change determining means is
In the channel arrangement changed by the channel changing means,
When a plurality of base station devices that are not in an interference relationship with each other are in an interference relationship with respect to a certain base station device, the channel is subdivided into narrow frequency band channels.
Wireless communication system according to any one of claims 3 or claim 4, characterized in that. The channel frequency band change determining means is
In the channel arrangement changed by the channel changing means,
When a plurality of base station devices that are not in an interference relationship with a base station device are in an interference relationship with each other, increase the evaluation value of the interference amount of the base station device or add a new penalty, and then Determine if the sum of the amount and penalty is reduced, and subdivide the channel into narrow frequency band channels,
Wireless communication system according to any one of claims 3 or claim 4, characterized in that. The central control station is
An interference detection channel determining means for designating use of the same channel for the plurality of base station devices;
Each of the plurality of base station apparatuses is
Interference information measuring means for measuring interference information of mutual communication using a channel designated by the centralized control station;
The wireless communication according to any one of claims 1 to 6 , comprising interference information output means for notifying the central control station of interference information obtained by the interference information measuring means. system. A channel assignment method for assigning channels used for communication to a plurality of base station devices,
A central control station connected to each of the plurality of base station apparatuses collects interference information notified from each base station apparatus, and an interference information collection step,
A channel assignment determination step for determining a channel assignment of each base station apparatus so that an interference amount is minimized from the interference information collected in the interference information collection step;
A channel notification step of notifying each of the base station devices of the allocation channel determined in the channel allocation determination step;
Wherein each base station apparatus, the channel used for communication, seen including a channel changing step of changing the channel notified in the channel notification step,
The central control station further includes an interference amount increase / decrease determination step for evaluating whether the interference amount is reduced by changing the currently determined channel assignment to another channel for each base station apparatus. ,
In the channel allocation determination step, when it is evaluated that the interference amount decreases in the interference amount increase / decrease determination step, the channel allocation method of the base station apparatus is updated based on the evaluation result .   A channel assignment method for assigning channels used for communication to a plurality of base station devices,
  A central control station connected to each of the plurality of base station apparatuses collects interference information notified from each base station apparatus, and an interference information collection step,
  A channel assignment determination step for determining a channel assignment of each base station apparatus so that an interference amount is minimized from the interference information collected in the interference information collection step;
  A channel notification step of notifying each of the base station devices of the allocation channel determined in the channel allocation determination step;
  A channel change step in which each base station apparatus changes a channel used for communication to the channel notified in the channel notification step;
  Including
  The centralized control station determines whether or not the amount of interference of each channel is larger than a predetermined threshold when the channel allocated to each base station device can be divided into channels with narrower frequency bands. A channel division determination step;
  Channel subdivision that divides the channel into narrow frequency band channels and redistributes the base station apparatus using the channel to new channels when it is determined in the channel division determination step that the amount of interference is greater than a threshold Distribution step,
  Channel integration determination for determining whether or not the interference amount of each channel is smaller than a predetermined threshold when the channel arrangement redistributed in the channel subdivision distribution step can be integrated into a channel having a wider frequency band. Steps,
  Channel integration in which, when it is determined in the channel integration determination step that the amount of interference is smaller than a threshold value, the channel is integrated into a wide frequency band channel and the base station apparatus using the channel is redistributed to a new channel Distribution step and
  A channel allocation method further comprising:   A channel assignment method for assigning channels used for communication to a plurality of base station devices,
  A central control station connected to each of the plurality of base station apparatuses collects interference information notified from each base station apparatus, and an interference information collection step,
  A channel assignment determining step for determining channel assignment of each base station apparatus so that the amount of interference is minimized from the interference information collected in the interference information collecting step;
  A channel notification step of notifying each of the base station devices of the allocation channel determined in the channel allocation determination step;
  A first channel change step in which each base station device changes a channel used for communication to the channel notified in the channel notification step;
  Including
  The central control station changes the currently determined channel assignment to another channel, thereby reducing or using the sum of the penalty determined from the frequency bandwidth being used and the amount of interference. An interference / penalty increase / decrease determination step for evaluating each base station device to determine whether the throughput index calculated from the frequency band being used and the amount of interference increases;
  A second channel change that changes the channel of the base station apparatus when it is determined in the interference / penalty increase / decrease determination step that the sum of the interference amount and the penalty decreases or when it is determined that the throughput index increases. Steps,
  In the channel arrangement determined in the second channel change step, the amount of interference and penalty can be reduced by subdividing channels into narrow frequency band channels or integrating a plurality of channels into wide frequency band channels. Channel frequency band change determination step for determining whether or not the sum can be reduced or whether the throughput index can be increased; and
  If it is determined in the channel frequency band change determination step that the sum of the interference amount and the penalty can be reduced, or if it is determined that the throughput index can be increased, the channel is divided into narrow frequency band channels. Or a channel frequency band change distribution step of integrating the plurality of channels into a wide frequency band channel and redistributing the base station apparatus using the channel to a new channel;
  A channel allocation method further comprising:   A channel assignment method for assigning channels used for communication to a plurality of base station devices,
  A central control station connected to each of the plurality of base station apparatuses collects interference information notified from each base station apparatus, and an interference information collection step,
  A channel assignment determination step for determining a channel assignment of each base station apparatus so that an interference amount is minimized from the interference information collected in the interference information collection step;
  A channel notification step of notifying each of the base station devices of the allocation channel determined in the channel allocation determination step;
  A first channel changing step in which each base station device changes a channel used for communication to the channel notified in the channel notifying step;
  Including
  The central control station collects interference information notified by each base station device and the frequency band function of a terminal that is a communication partner, and an interference information / terminal function collection step;
  Changing the currently assigned channel assignment to another channel reduces the sum of the penalty and the amount of interference calculated from the frequency bandwidth being used and the frequency bandwidth function of the terminal with which you are communicating. Or an interference / penalty increase / decrease determination step for evaluating each base station device to determine whether the throughput index calculated from the frequency band being used and the amount of interference increases,
  A second channel change that changes the channel of the base station apparatus when it is determined in the interference / penalty increase / decrease determination step that the sum of the interference amount and the penalty decreases or when it is determined that the throughput index increases. Steps,
  In the channel arrangement changed in the second channel changing step, the amount of interference and penalty can be reduced by subdividing channels into narrow frequency band channels or integrating a plurality of channels into wide frequency band channels. Channel frequency band change determination step for determining whether the sum of the values can be reduced or whether the throughput index can be increased;
  In the channel frequency band change determination step, when it is determined that the sum of the interference amount and the penalty can be reduced, or when it is determined that the throughput index can be increased, the channel is changed to a narrow frequency band. A channel frequency band change distribution step of dividing the channel into a plurality of channels or integrating the plurality of channels into a wide frequency band channel and redistributing the base station apparatus using the channel into a new channel;
  A channel allocation method further comprising:

Images