JP2013093708A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately switch channels to be allocated to a plurality of base station devices connected to a central control station device.SOLUTION: A central control station device determines switching time at which switching to one allocation pattern of a plurality of channel allocation patterns is performed; notifies a plurality of base station devices of the switching to the channel allocation pattern, at a timing earlier than the switching time to the channel allocation pattern by a prescribed time or more; and confirms that channels of the plurality of base station devices have been switched normally. The base station device notifies a communication partner terminal of the switching to the channel for a prescribed period before the switching time; changes its channel allocation to the channel allocation designated by the central control station device at the switching time; confirms that the terminal to be a communication partner has succeeded in the channel switching normally; and notifies the central control station device.

Description

  The present invention relates to a channel switching technique in wireless communication.

  In recent years, as a high-speed wireless access system using the 2.4 GHz band or the 5 GHz band, base station apparatuses (AP: Access point) based on the IEEE802.11g standard, the IEEE802.11a standard, and the like are widely spread. 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.

  However, the transmission rate described above is a transmission rate on the physical layer, and is not a data throughput effective for the user. Actually, since the transmission efficiency in the MAC (Medium Access Control) layer is about 50 to 70%, the throughput has an upper limit of about 30 Mbps.

  On the other hand, the communication speed of the wired LAN has been increasing due to the spread of FTTH (Fiber to the home). For this reason, it is assumed that further increase in transmission speed will be required in the wireless LAN in the future. Various spatial signal processing techniques such as MIMO and multi-user MIMO have been studied to increase the throughput of the radio section, but communication frequency bands have been expanded as other methods. In IEEE802.11a, a frequency band of 20 MHz is used for each channel. In IEEE802.11n, a frequency band of 40 MHz is used. Further, IEEE 802.11ac is considered up to 160 MHz when options are included. In this way, channel band expansion is progressing.

  Thus, the frequency band of the channel extends from IEEE802.11a to 11ac and is expanded eight times. However, no major expansion has been recognized for the entire frequency band that can be used for a wireless LAN. Therefore, with the spread of wireless terminals, frequency resources are becoming insufficient. For example, an environment in which a plurality of base station apparatuses use the same frequency band is increasing. For this reason, depending on the channel selected by the base station apparatus, the throughput may decrease due to the influence of packet signals from other base station apparatuses with which communication cells overlap each other, or the throughput efficiency of the entire system may decrease. There was a problem. Furthermore, channel bandwidths that can be selected by each base station apparatus are diversified. Therefore, when managing the frequency channel of the base station apparatus using the centralized control station (AC), it is necessary for the centralized control station to determine which frequency band to use as well as which frequency to use.

  A method of connecting a plurality of base station apparatuses to a central control station and assigning a channel to each base station apparatus is described in Patent Document 1. In Patent Document 1, a communication state such as throughput in a base station apparatus can be used as input information, and a channel can be selected so as to maximize system throughput.

JP 2007-74097 A

  However, the communication status changes with time. Therefore, the channel arrangement determined at a certain time is not necessarily optimal at different times. There is a need for a system that can select an appropriate channel arrangement according to changes in communication conditions. Also, it is difficult to determine a channel assignment that provides the maximum throughput for all base station devices. Therefore, in some base station apparatuses, the throughput may be lower than the required value.

  In view of the above circumstances, an object of the present invention is to provide a technique for appropriately switching channels allocated to a plurality of base station apparatuses connected to a centralized control station.

  One aspect of the present invention is a wireless communication system including a plurality of base station apparatuses and a centralized control station apparatus connected to the plurality of base station apparatuses, wherein the centralized control station apparatus includes a plurality of channel assignments A channel assignment pattern storage means for storing a pattern, a schedule means for determining a switching time for switching to one of the plurality of channel assignment patterns, and a time earlier than a switching time for the channel assignment pattern by a predetermined time or more, Channel assignment pattern notification means for notifying the plurality of base station apparatuses of switching to a channel assignment pattern; and base station channel change confirmation means for confirming that the channels of the plurality of base station apparatuses have been switched normally. The base station device is a communication partner terminal before the switching time Channel switching notifying means for notifying channel switching for a certain period of time, channel changing means for changing to the channel assignment designated for the centralized control station device at the switching time, and that the terminal as the communication partner has successfully successfully switched the channel And a channel change normal end notification means for confirming and notifying the centralized control station apparatus.

  One aspect of the present invention is the wireless communication system described above, wherein the scheduling unit of the centralized control station apparatus periodically switches a plurality of channel allocation patterns of the channel allocation pattern storage unit at regular time intervals.

  One aspect of the present invention is the above wireless communication system, wherein the centralized control station device includes a number of bits of data transmitted from each base station device and data received by each base station device from a plurality of base station devices. The number of bits, the collision frequency of packets generated by communication of each base station device, the number of bits of data buffered in each base station device, the throughput at which each base station device and its communication partner (terminal device) communicated, or Communication status storage means for collecting and storing information on the number of bits, and channel allocation pattern storage means for calculating and storing a channel allocation pattern from the stored communication status.

  One aspect of the present invention is the above wireless communication system, wherein the centralized control station device includes a number of bits of data transmitted from each base station device and data received by each base station device from a plurality of base station devices. The number of bits, the collision frequency of packets generated by communication of each base station device, the number of bits of data buffered in each base station device, the throughput at which each base station device and its communication partner (terminal device) communicated, or Communication status storage means for collecting and storing information on the number of bits with respect to time, channel allocation pattern storage means for calculating and storing a channel assignment pattern from the stored communication status, and the stored time Depending on the communication status for each channel, determine the optimal channel allocation pattern for each time and assign the channel so that the channel allocation pattern is used for that time. Further comprising a scheduling means for determining patterns and switching times, the.

  One aspect of the present invention is the above wireless communication system, in which the base station apparatus switches to a channel assignment pattern designated by the central control station apparatus, and then the number of bits of data transmitted by each base station apparatus , The number of bits of data received by each base station device, the collision frequency of packets generated by communication of each base station device, the number of bits of data buffered in each base station device, each base station device and its communication partner ( A channel allocation pattern evaluation unit that collects information on throughput or the number of bits communicated with the terminal device as an evaluation index of the effect of the channel allocation pattern, and the channel allocation pattern evaluation result to the centralized control station device. An evaluation result notification means for notifying, wherein the centralized control station apparatus determines a channel allocation pattern according to the evaluation result. Change the emissions, further comprising a channel allocation pattern updating means for storing.

  According to the present invention, it is possible to appropriately switch channels assigned to a plurality of base station apparatuses connected to a centralized control station.

It is a figure showing the system configuration | structure of the radio | wireless system of 1st Embodiment. It is a figure which shows the channel used in a radio | wireless system. It is a figure showing the relationship (channel condition) of the interference in each channel. It is a figure which shows other system AP10 detected in each system AP. It is a figure which shows the specific example of a channel allocation pattern. It is a figure which shows the 1st example of the flow of operation | movement of a radio | wireless system. It is a figure which shows the 2nd example of the flow of operation | movement of a radio | wireless system. It is a figure which shows the specific example of the determination method of the schedule of a channel allocation pattern. It is a schematic block diagram showing the function structure of system AP. It is a schematic block diagram showing the function structure of a centralized control station. It is a flowchart which shows the flow of a process corresponded to a 1st example (FIG. 6) among the flow of processes of the radio | wireless system of 1st Embodiment. It is a flowchart which shows the flow of a process in the case of processing based on a statistic value as shown in FIG. 8 among the flow of processes of the radio | wireless system of 1st Embodiment. It is a flowchart which shows the flow of a process corresponded to a 2nd example (FIG. 7) among the flow of processes of the radio | wireless system of 1st Embodiment. It is a figure showing the specific example of the channel allocation to each system AP.

  Hereinafter, an embodiment of the present invention will be described. In the following description, the base station apparatus and the central control station may be described as “AP” and “AC”, respectively.

[First Embodiment]
FIG. 1 is a diagram illustrating a system configuration of a wireless system 1 according to the first embodiment. Base station apparatuses 10-1, 10-2, 10-3, 10-4, and 10-5 are connected to the centralized control station 20. There are six base station apparatuses 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6) that are not connected to the centralized control station 20. In the following description, the base station apparatus 10 connected to the centralized control station 20 is referred to as “system AP”. Further, the base station apparatus 11 that is not connected to the central control station 20 is referred to as “interference AP”. In the wireless system 1, the throughput of the system AP is improved.

  FIG. 2 is a diagram illustrating channels used in the wireless system 1. The channel arrangement in the wireless system 1 is an example of a band that can be used in the IEEE 802.11 5 GHz band, as shown in FIG. 2, for example. The channel described above is an example, and the channel used in the wireless system 1 may be another frequency.

  The centralized control station 20 designates a channel to be used for communication from the channels A to η in the bands of 20 MHz, 40 MHz, 80 MHz, and 160 MHz for each system AP10. The centralized control station 20 selects a primary channel from the 20 MHz channels P to η. For example, when communicating using channel A, centralized control station 20 sets one 20 MHz channel among channels P to W as a primary channel and the other channels as secondary channels.

  FIG. 3 is a diagram illustrating an interference relationship (channel condition) in each channel. Specifically, the table of FIG. 3 represents the primary channel and the secondary channel used by the interference AP that is the source of the interference detected in each system AP 10. The double circle represents a basic 20 MHz channel (primary channel). One circle represents a secondary channel existing in the same 40 MHz channel as the basic 20 MHz channel. The triangle represents the other 40 MHz secondary channel present in the same 80 MHz channel. The square represents the secondary channel corresponding to the other 80 MHz existing in the same 160 MHz channel.

  For example, in the 160 MHz channel A, the system AP 10-1 detects an interference AP having the channel Q as a primary channel and an interference AP having the channel T as a primary channel. Further, the system AP 10-1 detects an interference AP having the channel X as a primary channel in the 80 MHz channel E. The system APs 10-1 to 10-5 can estimate the used channel of the interfering AP as shown in FIG. 3 by observing the used channel of the interfering AP. Each system AP 10-1 to 10-5 can transmit the estimation result to the centralized control station 20.

  FIG. 4 is a diagram illustrating another system AP 10 detected in each system AP 10. In FIG. 4, one circle indicates that the system AP10 shown on the left side of the table detects the other system AP10 shown on the upper side of the table. Each system AP 10 informs the central control station 20 of another system AP 10 detected by its own device. For example, the system AP 10-1 detects a system AP 10 (10-2, 10-3, 10-4) other than the system AP 10-5.

  The centralized control station 20 of the first embodiment determines a plurality of channel assignment patterns for each system AP 10 according to the estimated channel conditions. The channel allocation pattern determination method can be determined by various methods such as maximizing the system throughput, maximizing the throughput of the system AP having the minimum throughput, and random arrangement. However, regardless of which method is used, there is a system AP 10 that can obtain a high throughput and an AP 10 that can obtain only a low throughput, causing a problem in fairness of the throughput. In order to solve this problem, the central control station 20 selects a plurality of channel assignment patterns as described above, and switches the selected channel assignment pattern. By this switching, the wireless system 1 can improve the fairness of the throughput.

  FIG. 5 is a diagram illustrating a specific example of a channel assignment pattern. FIG. 5 shows the channels specified for each system AP10. The characters shown in parentheses in FIG. 5 indicate a 20 MHz channel that is a primary channel. Thus, the centralized control station 20 determines a plurality of channel assignment patterns for the system AP 10 and switches them at regular intervals. By this switching, the fairness of the throughput can be improved.

  FIG. 6 is a diagram illustrating a first example of the operation flow of the wireless system 1. In the first example, the central control station 20 notifies each system AP 10 every time the channel is switched. In FIG. 6, there are N system APs 10 (10-1 to 10-N). First, the central control station 20 (AC) determines a plurality of channel assignment patterns. This determination is made before time t0 in FIG. Thereafter, at time t0, the centralized control station 20 transmits a channel change notification A to each system AP10 (AP10-1 to AP10-N).

  Each system AP 10-1 to 10 -N receives from the time t 1 after receiving the notification that each terminal connected to its own device “transfers to the channel specified by the channel change notification A from time t 2”. Notify the device. At time t2, each system AP 10-1 to 10-N changes the channel used for communication with the terminal device to the channel specified by the channel change notification A.

  When each system AP 10-1 to 10-N confirms that the terminal device of the communication partner has correctly handled the channel change, the system AP 10-1 to 10-N notifies the central control station 20 that the channel change has been completed. In addition, since the time required to confirm that the channel change has been normally completed changes in each system AP 10, it is not necessary to accurately notify the completion of the channel change at the same time. Although it is described in FIG. 6 that the channel change completion is notified at time t3, the system AP 10 that cannot complete the channel change notifies the channel change completion at a timing later than time t3.

  When a predetermined timing (for example, time t4 in FIG. 6) arrives, the centralized control station 20 selects another channel assignment pattern from a plurality of already determined channel assignment patterns. Then, the centralized control station 20 transmits a channel change notification A to each system AP 10-1 to 10-N based on the newly selected channel assignment pattern.

  FIG. 7 is a diagram illustrating a second example of the operation flow of the wireless system 1. In the second example, the channel assignment pattern and its schedule are notified to each system AP 10 by the channel change notification B. Each system AP 10 changes its own channel assignment according to the timing designated by the channel change notification B. This will be described in more detail below.

  In the example of FIG. 7, each system AP 10 is already communicating with the first channel allocation pattern at time t0. The centralized control station 20 determines a second channel assignment pattern different from the first channel assignment pattern and its schedule. This determination is made before time t0 in FIG. For example, the centralized control station 20 uses the second channel assignment pattern from time t2 to time t6, and determines a schedule that returns to the first channel assignment pattern after t6.

  The channel change notification B transmitted by the centralized control station 20 includes information indicating the second channel allocation pattern and the time interval (t2 to t6) in which this channel allocation is performed. Each system AP10 starts to notify the terminal device of a channel change at time t1 in order to perform communication based on the second channel assignment pattern between time t2 and time t6. At time t2, each system AP 10 changes the channel. When the channel change is normally performed, each system AP 10 transmits a channel change completion notification to the centralized control station 20. In the example of FIG. 7, a channel change completion notification is transmitted at time t3. Thereafter, at a timing (time t5) a predetermined time before time t6, each system AP 10 notifies each terminal device that communication is performed using the first channel allocation pattern from time t6. Each system AP 10 changes the channel at time t6, and when the channel change is completed normally, notifies the central control station 20 of the change (time t7).

  Thus, in the second example, each system AP 10 is notified of the channel assignment pattern and its schedule. Each system AP 10 autonomously changes the channel at the timing according to the notified schedule.

  FIG. 8 is a diagram illustrating a specific example of a method for determining a schedule of channel assignment patterns. FIG. 8 is a table showing an index of throughput with which communication is performed in the system AP10 with respect to time. FIG. 8 is a table obtained by the centralized control station 20 collecting information related to communication for each system AP 10 and calculating its statistical value (average, median, cumulative value, etc.). The numerical value shown in FIG. 8 is this statistical value.

  The information (evaluation information) used for calculating the statistical value includes, for example, the number of bits of data transmitted by each system AP 10, the number of bits of data received by each system AP 10, and packet collisions caused by communication of each system AP 10. The frequency, the number of bits of data buffered in each system AP 10, the throughput or number of bits communicated between each system AP 10 and its communication partner (terminal device), and the like. In addition, for calculation of statistical values, data for several days may be used, data for each day of the week or data for each time may be used, and daily data for the year is used. Also good.

  As described above, the central control station 20 grasps what kind of communication each system AP 10 statistically performs with respect to time, whereby appropriate channel assignment can be determined according to time. In the example of FIG. 8, the system AP10 having the highest throughput index is described in the rightmost column. As is apparent from FIG. 8, the throughput required for each system AP 10 varies with time. For example, it is possible to increase the overall system throughput of the wireless system 1 by applying channel allocation that can be expected to have a high throughput to the system AP 10 having the highest throughput at each time.

  In FIG. 8, when AP10-1 and AP10-2 are seeking high throughput, channel allocation pattern 1 is used. When AP10-3 to 10-5 is seeking high throughput, channel allocation pattern 2 is selected. May be scheduled to be used.

  FIG. 9 is a schematic block diagram illustrating a functional configuration of the system AP10. The system AP 10 includes a first communication unit 101, a second communication unit 102, and a control unit 103. The first communication unit 101 wirelessly communicates with a plurality of communication terminals using a channel specified by the central control station 20. The second communication unit 102 communicates with a higher-level device on the network and the central control station 20. The control unit 103 relays the data received from the terminal device via the first communication unit 101 to the host device of the network via the second communication unit 102 according to the destination. In addition, the control unit 103 relays data received from the host device via the second communication unit 102 to the terminal device via the first communication unit 101 according to the destination. In addition, the control unit 103 communicates with the central control station 20 via the second communication unit 102 and performs control related to the channel assignment pattern. In addition, the control unit 103 controls the first communication unit 101 so as to wirelessly communicate with the communication terminal with the designated channel assignment. In addition, the control unit 103 transmits a channel change terminal notification and a channel change completion notification.

  FIG. 10 is a schematic block diagram showing a functional configuration of the central control station 20. The centralized control station 20 includes a channel assignment pattern generation unit 201, a channel assignment pattern storage unit 202, a control unit 203, and a communication unit 204. The channel assignment pattern generation unit 201 generates a plurality of channel assignment patterns. The channel assignment pattern storage unit 202 stores a plurality of channel assignment patterns generated by the channel assignment pattern generation unit 201. The control unit 203 grasps the communication status based on the information obtained from the communication unit 204 and determines an appropriate channel assignment and timing (schedule) from the channel assignment pattern of the channel assignment pattern storage unit 202. The control unit 203 transmits a channel change notification to each system AP 10 via the communication unit 204 based on the determined schedule. The communication unit 204 communicates with a plurality of system APs 10.

  FIG. 11 is a flowchart illustrating a process flow corresponding to the first example (FIG. 6) in the process flow of the wireless system 1 according to the first embodiment. First, when the system AP 10 is connected to the central control station 20, the central control station 20 collects interference relation information from each system AP 10 (step S101). The interference relation information is, for example, information on a signal received from an interference AP in each system AP 10, information on communication cell overlap between the system APs 10, and the like. The centralized control station 20 generates and stores a plurality of channel assignment patterns based on the obtained interference relation information (step S102). Next, the centralized control station 20 selects one of a plurality of stored channel allocation patterns, and transmits a channel allocation pattern change notification to each system AP 10 (step S103).

  When the channel assignment pattern change notification is received, the system AP 10-i (i = 1, 2,..., N) starts notifying the terminal device serving as the communication partner about the channel assignment change (step S1). S104-i). The system AP 10-i continues the channel change notification until the channel change timing comes (step S105-i). When the channel change timing comes, the system AP 10-i changes the channel used for wireless communication with the terminal device (step S106-i). The system AP 10-i confirms whether or not the channel change has been normally completed with all the terminal devices with which the own device is a communication partner (step S107-i). When there is a terminal device that has failed to change the channel, the system AP 10-i starts over from the channel change notification. On the other hand, when the channel change is normally completed for all the terminal devices, the system AP 10-i notifies the central control station 20 of the completion of the channel change (step S108-i).

FIG. 12 is a flowchart illustrating a processing flow when processing is performed based on a statistical value as illustrated in FIG. 8 in the processing flow of the wireless system 1 of the first embodiment.
The centralized control station 20 generates and stores a plurality of channel assignment patterns without collecting interference information such as the channel usage status of the interference AP and the communication cell overlap relationship between the system APs (step S102). The centralized control station 20 selects one of a plurality of channel assignment patterns, and transmits a channel assignment pattern change notification to each system AP 10 (step S103).

  When the channel assignment pattern change notification is received, the system AP-i starts notifying the terminal device serving as a communication partner about the channel assignment change (step S104-i). The system AP 10-i continues the channel change notification until the channel change timing comes (step S105-i). When the channel change timing comes, the system AP 10-i changes the channel used for wireless communication with the terminal device (step S106-i). The system AP 10-i confirms whether or not the channel change has been normally completed with all the terminal devices with which the own device is a communication partner (step S107-i). When there is a terminal device that has failed to change the channel, the system AP 10-i starts over from the channel change notification. On the other hand, when the channel change is normally completed for all the terminal devices, the system AP 10-i notifies the central control station 20 of the completion of the channel change (step S108-i).

  The system AP 10-i notifies the central control station 20 of the evaluation information (step S109-i). The centralized control station 20 calculates the statistical value based on the evaluation information notified from each system AP 10 and updates the channel assignment pattern stored in the channel assignment pattern storage unit 202 (step S102). The following information can be used as the evaluation information. Interference AP and system AP transmission signal reception information on the selected channel, packet collision rate, time required to acquire access right, number of wireless terminals receiving signals on the selected channel, communication occupation rate of other APs, maximum Throughput, etc.

  FIG. 13 is a flowchart illustrating a process flow corresponding to the second example (FIG. 7) in the process flow of the wireless system 1 according to the first embodiment. First, when the system AP 10 is connected to the central control station 20, the central control station 20 collects interference relation information from each system AP 10 (step S101). The centralized control station 20 generates and stores a plurality of channel assignment patterns based on the obtained interference relation information (step S102). Next, the centralized control station 20 selects a channel assignment pattern used in the wireless system 1 from a plurality of stored channel assignment patterns. The central control station 20 determines a schedule for applying the selected channel assignment pattern to the wireless system 1. Then, the centralized control station 20 notifies each system AP 10 of the selected channel assignment pattern and schedule (step S103).

  When the channel assignment pattern and the schedule are notified, the system AP 10-i waits until the channel change timing designated as the schedule approaches. When the remaining time until the channel change timing falls within the threshold (T), the system AP 10-i starts notifying the terminal device serving as a communication partner about the channel assignment change (step S104-i). The system AP 10-i continues the channel change notification until the channel change timing comes (step S105-i). When the channel change timing comes, the system AP 10-i changes the channel used for wireless communication with the terminal device (step S106-i). The system AP 10-i confirms whether or not the channel change has been normally completed with all the terminal devices with which the own device is a communication partner (step S107-i). When there is a terminal device that has failed to change the channel, the system AP 10-i starts over from the channel change notification. On the other hand, when the channel change is normally completed for all the terminal devices, the system AP 10-i notifies the central control station 20 of the completion of the channel change (step S108-i). The system AP 10-i changes the channel according to the notified schedule until the channel change schedule notified from the centralized control station 20 ends.

  In the wireless system 1 configured as described above, the central control station 20 that controls the frequency channels of the plurality of system APs 10 can appropriately switch channels assigned to the system APs 10. Specifically, the fairness of channel assignment to each system AP 10 can be improved. Further, by calculating the statistical values as shown in FIG. 8 and updating the channel allocation pattern, channel allocation corresponding to the time change of the wireless environment becomes possible.

<Modification>
The central control station 20 may be configured not to include the channel assignment pattern generation unit 201. In this case, the channel assignment pattern storage unit 202 stores a plurality of channel assignment patterns in advance.

  An example of a channel assignment determination method is shown below. In order to maximize the throughput of the AP, which is the minimum throughput, the observed interference conditions (number of APs / terminals transmitting interference signals, time occupancy of interference signals, number of different primary channels of APs / terminals transmitting interference signals) From the one with a high packet collision rate), it is possible to determine one channel at a time with a high throughput. For example, when an interfering AP is detected as shown in FIG. 3, channels are determined in order from the AP 10-4 having a large number of observed channels, and a system AP is newly generated by sequentially determining the channel of the system AP. The channel to be used can be determined in consideration of the interference condition. Or conversely, it may be determined from those having less interference conditions. Or you may determine from the thing with the large request | requirement throughput notified from system AP10. Or you may determine from the thing with the high priority of the predetermined system AP10. Alternatively, the specific system AP10 may be determined to have a high throughput. Alternatively, the order may be determined in descending order of the number of terminals under the system AP10. Or you may determine in order with few numbers of the terminal of system AP10. Or you may select at random.

  When transmitting the channel change notification, the central control station 20 may determine for each system AP 10 whether or not the channel assignment before the change and the channel assignment after the change are the same. The central control station 20 may be configured not to transmit a channel change notification to the system AP 10 having the same channel assignment.

  When receiving the channel change notification, the system AP 10 may determine whether or not the channel assignment before the change and the channel assignment after the change are the same. When the channel assignment is the same, the system AP 10 may be configured not to perform any one, a plurality, or all of channel change terminal notification, channel change execution, and channel change completion notification.

  The wireless system 1 may operate as follows. First, the central control station 20 randomly determines and stores a plurality of channel assignment patterns. Then, the centralized control station 20 performs wireless communication between each system AP 10 and the terminal device as shown in FIG. 6 and FIG. Thereafter, the number of bits transmitted by the centralized control station 20 to each system AP10, the number of bits received by the centralized control station 20 from each system AP10, the number of bits communicated in the radio section in the communication cell of each system AP10, the throughput, The system AP 10 collects information such as the number of bits stored as a buffer. The central control station 20 evaluates the effect of each channel allocation pattern based on the collected information. The centralized control station 20 deletes the channel assignment pattern having a low effect and performs communication as shown in FIGS. 6 and 7 using the channel assignment pattern having a high effect. The channel allocation pattern with high effect is, for example, a state in which the number of bits communicating between the system AP 10 and its terminal device is large, the throughput is high, packet collision is unlikely to occur, or the number of buffered bits is small. Is a channel assignment pattern that causes

  11 and 13, the process of step S101 may be repeatedly executed periodically or only when the wireless communication environment has changed. The change in the environment of wireless communication includes the addition of a new system AP10, the addition of a new terminal device, the observation of interference from other systems such as radar, and the change of data bits transmitted from the centralized control station 20 to the system AP10. If the data bit change received by the centralized control station 20 from the system AP 10 exceeds a threshold value, or if the amount of data buffered in each system AP exceeds a certain threshold value, a new priority AP is provided. And so on.

  Steps S103 of FIGS. 11 to 13 may be periodically performed at predetermined time intervals. Further, it may be performed at a fixed time of the day, may be performed when a change is requested from the system AP 10, or may be performed when the environment of wireless communication is changed.

[Second Embodiment]
In the wireless system 1 of the second embodiment, the channel assignment pattern storage unit 202 of the centralized control station 20 stores a channel assignment pattern (priority pattern) that realizes high throughput in a specific system AP10 (priority system AP). Then, by applying a priority pattern in a time zone in which it is desired to increase the throughput of the priority system AP, it is possible to provide a throughput according to the request of the priority system AP or a user who owns the priority system AP.

  FIG. 14 is a diagram illustrating a specific example of channel assignment to each system AP 10. FIG. 14 shows channel assignment patterns when the system APs 10-1 to 10-5 become the priority system APs in order from the top. Each priority channel allocation pattern is determined so as to maximize the throughput in a certain priority AP.

  The central control station 20 selects the priority system AP. The centralized control station 20 may select the system AP 10 designated by the user or the system administrator as the priority system AP. For example, the central control station 20 selects the system AP 10 having the largest throughput and the maximum number of bits in communication within a predetermined period You may choose as Then, the central control station 20 selects a channel assignment pattern (priority pattern) corresponding to the selected priority system AP, and realizes wireless communication based on the selected priority pattern.

The flow of processing of the wireless system 1 according to the second embodiment will be described using the block diagrams of FIGS.
In the flowcharts of FIGS. 11 and 13, when a priority system AP and a time zone in which the system AP is prioritized are designated (step S110), the central control station 20 uses the channel assignment pattern for realizing high throughput for the priority system AP. And notifies each system AP10. Then, wireless communication with a priority pattern is performed by the processing in steps S104 to S109.

  Further, at the timing when the priority time zone ends, the central control station 20 notifies each system AP 10 of the change to the original channel assignment pattern (step S103). Thereafter, wireless communication is performed with the original channel assignment pattern by the processing of step S104 to step S109.

In the flowchart of FIG. 12, when a priority system AP and a time zone in which the system AP is prioritized are designated (step S110), the centralized control station 20 sets a channel assignment pattern that realizes high throughput for the priority system AP, The system AP 10 is notified of the change timing and the timing for returning to the original channel assignment pattern. Thereafter, wireless communication with a priority pattern is performed by the processing in steps S104 to S109. In the flowchart of FIG. 12, the priority channel assignment can be updated in S102 by verifying the effect of the used priority channel assignment.
According to the second embodiment configured as described above, the throughput of the priority system AP can be temporarily increased as necessary.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Wireless system, 10 ... System AP (base station apparatus), 11 ... Interfering AP, 20 ... Central control station (central control station apparatus), 101 ... First communication part, 102 ... Second communication part, 103 ... Control part , 201 ... Channel allocation pattern generation unit, 202 ... Channel allocation pattern storage unit, 203 ... Control unit, 204 ... Communication unit

Claims (5)

A wireless communication system comprising a plurality of base station devices and a centralized control station device connected to the plurality of base station devices,
The central control station device
Channel assignment pattern storage means for storing a plurality of channel assignment patterns;
Scheduling means for determining a switching time for switching to one channel assignment pattern among a plurality of channel assignment patterns;
Channel allocation pattern notification means for notifying the plurality of base station devices of switching to a channel allocation pattern at a time earlier than a predetermined time by the channel allocation pattern switching time;
Base station channel change confirmation means for confirming that the channels of the plurality of base station devices have been switched normally,
The base station device
A channel switching notification means for notifying a communication partner terminal of channel switching for a certain period of time before the switching time;
Channel changing means for changing to the channel assignment specified in the centralized control station apparatus at the switching time;
A wireless communication system comprising: a channel change normal end notification means for confirming that a terminal serving as a communication partner has successfully successfully switched channels and notifying the central control station device. The wireless communication system according to claim 1,
The scheduling unit of the centralized control station apparatus periodically switches a plurality of channel allocation patterns of the channel allocation pattern storage unit at regular intervals;
It is characterized by that. The wireless communication system according to claim 1,
The central control station device
The number of bits of data transmitted by each base station device from a plurality of base station devices, the number of bits of data received by each base station device, the collision frequency of packets generated by communication of each base station device, Communication status storage means for collecting and storing information on the number of bits of buffered data, the throughput or the number of bits communicated between each base station device and its communication counterpart (terminal device),
Channel assignment pattern storage means for calculating and storing a channel assignment pattern from the stored communication status;
Is further provided. The wireless communication system according to claim 1,
The central control station device
The number of bits of data transmitted by each base station device from a plurality of base station devices, the number of bits of data received by each base station device, the collision frequency of packets generated by communication of each base station device, Communication status storage means for collecting and storing information on the number of bits of buffered data, the throughput or the number of bits communicated between each base station device and its communication counterpart (terminal device), and time;
Channel assignment pattern storage means for calculating and storing a channel assignment pattern from the stored communication status;
Schedule means for determining an optimum channel allocation pattern for each time according to the communication status for the stored time, and determining a channel allocation pattern and a switching time so as to use the channel allocation pattern for the time;
Is further provided. The wireless communication system according to claim 1,
The base station device
After switching to the channel assignment pattern specified by the centralized control station device, the number of data bits transmitted by each base station device, the number of data bits received by each base station device, and the communication of each base station device occurred. Information about the frequency of packet collision, the number of bits of data buffered in each base station device, the throughput or the number of bits communicated between each base station device and its communication partner (terminal device), and the effect of the channel allocation pattern Channel allocation pattern evaluation means for collecting information as an evaluation index of
An evaluation result notification means for notifying the central control station device of the channel allocation pattern evaluation result,
The central control station apparatus further includes channel assignment pattern update means for changing and storing the channel assignment pattern according to the evaluation result.

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