JP7619619B2 - Information and communication system, monitor device, terminal device, representative value acquisition method, transmission rate acquisition method, and program - Google Patents

Description

Application of Article 30, paragraph 2 of the Patent Act February 24, 2021 Announced via https://www.ieice.org/ken/paper/20210303UC2X/, https://www.ieice.org/ken/user/index.php?cmd=login&back_url=https%3A%2F%2Fwww.ieice.org%2Fken%2Fpaper%2F20210303UC2X%2F March 3, 2021 Announced via the "Mobile Communications Workshop" (held online) of the Institute of Electronics, Information and Communication Engineers, Inc., and https://zoom.us/j/85036162630

The present invention relates to a terminal device that performs wireless communication with a wireless base station.

As various applications with different uses, required quality, and importance are developed, and autonomous distributed wireless communication systems in the ISM band (e.g., 2.4 GHz band) become more widespread, situations can arise where applications do not run satisfactorily due to congestion. Since wireless resources are limited, there may not be enough resources to run all applications satisfactorily. In addition, everyday electronic devices such as microwave ovens, power amplifiers, and speakers generate noise power in the same frequency band as the communication channel, which may degrade communication quality. To solve these problems, research and development is being conducted on autonomous distributed wireless communication systems that enable more important applications to be operated in various radio wave environments with quality that satisfies humans.

Previous research has proposed a network that controls an autonomous distributed wireless communication system with the aim of maximizing the number of terminals that satisfy QoE (Quality of Experience: user satisfaction), such as a wireless resource control method that uses QoE (Quality of Experience: user satisfaction) as an evaluation index and a method of reconfiguring the network based on information collected from the entire system (see, for example, Patent Document 1). In Patent Document 1, a management server that collects information about the entire system is provided, and the connection destination of terminal devices in the network and the frequency used by wireless base stations (e.g., access points, etc.) in the network are changed using the amount of resources required to satisfy the required QoE of the network managed by the management server as an index. As a result, even if there is an application that makes excessive resource requests that were previously difficult to satisfy, the unused resources generated by reconfiguring the network can be allocated to the application to satisfy the QoE, and the number of applications that can be accommodated by the entire system can be increased.

When changing the connection destination of a terminal device to satisfy the required QoE in the network, this management server uses the received signal strength indication (RSSI) of the frame sent by the wireless base station to select the physical layer transmission rate that can be used for each link. This makes it possible to grasp the desired resource amount of the terminal device and estimate the number of applications that can be accommodated in the wireless base station.

JP 2016-152469 A

However, when selecting this physical layer transmission rate, it does not take into account weak interference power below the carrier sense threshold that may be generated from communication devices, electronic devices, etc. If such weak interference power is generated in the vicinity of the network where the transmission rate is selected, the SINR (Signal to Interference and Noise Ratio) of each link will decrease by the amount of that interference power, and a transmission rate that does not satisfy the desired error rate (BER: Bit Error Rate) may be selected. As a result, the QoE will decrease by the amount of the unexpected transmission error, and there is a risk that the required QoE cannot be met.

Generally speaking, there has been a demand to be able to select an appropriate transmission rate that can satisfy the required QoE.

The present invention has been made to solve the above problems, and aims to provide a terminal device etc. for obtaining an appropriate transmission rate that can satisfy the required QoE.

In order to achieve the above object, a terminal device according to one aspect of the present invention is a terminal device that performs wireless communication with a wireless base station, and includes a wireless communication unit that receives a representative value of interference power that is less than a carrier sense threshold, a calculation unit that calculates a signal-to-interference-plus-noise ratio using the representative value of interference power and the reception strength of a wireless signal transmitted from the wireless base station, and a transmission rate acquisition unit that acquires a transmission rate corresponding to the signal-to-interference-plus-noise ratio calculated by the calculation unit using transmission rate correspondence information that associates the signal-to-interference-plus-noise ratio with a transmission rate.

With this configuration, it becomes possible to obtain an appropriate transmission rate that can satisfy the required QoE by obtaining the transmission rate using the SINR calculated using a representative value of the interference power that is less than the carrier sense threshold.

In addition, in a terminal device according to one aspect of the present invention, when there is an uncommunicated application that cannot perform wireless communication, the transmission rate acquisition unit acquires the transmission rate for each connectable wireless base station, and the wireless communication unit transmits to the wireless base station information that enables the wireless base station that wirelessly communicates with the terminal device to transmit to the management server the required resource amount, which is the wireless resource necessary for wireless communication of the uncommunicated application for each wireless base station that the terminal device can connect to, calculated according to the transmission rate, and the priority of the uncommunicated application, and when the management server determines a new wireless base station to which the terminal device is to be connected in response to the transmission, a connection destination change instruction is received from the management server to change the connection destination in accordance with the determination result by the management server, and when the wireless communication unit receives the connection destination change instruction, a control unit is further provided that controls the wireless base station to which the wireless communication unit is connected in response to the connection destination change instruction.

With this configuration, a transmission rate that satisfies the required QoE is obtained, allowing the management server to perform more appropriate control.

In addition, in a terminal device according to one aspect of the present invention, the wireless communication unit may perform wireless communication with a wireless base station at the transmission rate acquired by the transmission rate acquisition unit.

With this configuration, wireless communication is performed at a transmission rate that satisfies the required QoE, making it possible to achieve wireless communication with an error rate that corresponds to the required QoE.

In addition, a monitoring device according to one aspect of the present invention includes a receiving unit that receives radio waves and acquires the received power of the received radio waves, a creating unit that creates a histogram of the received power for each predetermined power width using the received power acquired by the receiving unit at a predetermined sampling interval during a measurement period, an acquiring unit that acquires a representative value of interference power that is less than the carrier sense threshold using the histogram of the received power created by the creating unit, and a transmitting unit that transmits the representative value acquired by the acquiring unit.

This configuration makes it possible to obtain a representative value of interference power below the carrier sense threshold, which is used to obtain a transmission rate that satisfies the required QoE.

In addition, in a monitoring device according to one aspect of the present invention, the representative value may be a received power at which the cumulative probability of a probability density function obtained from a histogram of received power in a range above the noise floor and below the carrier sense threshold is a predetermined value.

This configuration makes it less likely that unexpected quality degradation will occur compared to when the average value is used as the representative value.

In addition, an information communication system according to one aspect of the present invention includes the above-mentioned monitor device and the above-mentioned terminal device that acquires a transmission rate using a representative value transmitted from the monitor device.

With this configuration, a transmission rate that satisfies the required QoE can be obtained using a representative value of interference power below the carrier sense threshold obtained by the monitoring device.

In addition, a transmission rate acquisition method according to one aspect of the present invention is a transmission rate acquisition method processed in a terminal device that performs wireless communication with a wireless base station, and includes the steps of receiving a representative value of interference power that is less than a carrier sense threshold, calculating a signal-to-interference-plus-noise ratio using the representative value of interference power and the reception strength of a wireless signal transmitted from the wireless base station, and acquiring a transmission rate corresponding to the calculated signal-to-interference-plus-noise ratio using transmission rate correspondence information that associates the signal-to-interference-plus-noise ratio with the transmission rate.

In addition, a representative value acquisition method according to one aspect of the present invention includes the steps of receiving radio waves and acquiring the received power of the received radio waves, creating a histogram of the received power for each predetermined power width using the received power acquired at a predetermined sampling interval during the measurement period, acquiring a representative value of the interference power below the carrier sense threshold using the created histogram of the received power, and transmitting the acquired representative value.

A terminal device according to one aspect of the present invention can obtain a transmission rate that satisfies the required QoE.

FIG. 1 is a block diagram showing a configuration of an information communication system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a management server according to the embodiment; FIG. 2 is a block diagram showing the configuration of a wireless base station according to the embodiment; FIG. 2 is a block diagram showing a configuration of a monitor device according to the embodiment; FIG. 2 is a block diagram showing the configuration of a terminal device according to the embodiment; A flowchart showing the operation of the management server according to the embodiment. A flowchart showing the operation of the management server according to the embodiment. A flowchart showing the operation of the management server according to the embodiment. A flowchart showing the operation of the wireless base station according to the embodiment. A flowchart showing the operation of the monitor device according to the embodiment. A flowchart showing the operation of the terminal device according to the embodiment. FIG. 2 is a diagram for explaining the creation of a histogram in the embodiment; FIG. 13 is a diagram showing an example of a histogram of received power in the embodiment; FIG. 13 is a diagram showing an example of a probability density function of received power in the embodiment; FIG. 13 is a diagram showing an example of the complementary cumulative probability of a probability density function of received power in the embodiment; FIG. 13 is a diagram showing an example of transmission rate correspondence information according to the embodiment; FIG. 2 is a schematic diagram showing an example of the appearance of a computer system according to the embodiment; FIG. 2 shows an example of the configuration of a computer system according to the embodiment.

The following describes an information and communication system, a monitor device, a terminal device, and the like according to the present invention using an embodiment. In the following embodiments, components and steps with the same reference numerals are the same or equivalent, and repeated explanations may be omitted. The information and communication system according to this embodiment has a monitor device that obtains a representative value of interference power that is less than the carrier sense threshold, and a terminal device that obtains a transmission rate using the representative value.

Figure 1 is a block diagram showing the configuration of an information and communication system according to this embodiment. The information and communication system according to this embodiment includes a management server 1, wireless base stations 2-1 and 2-2, monitoring devices 3-1 and 3-2, and terminal devices 4-1 to 4-4. A wireless communication system consisting of one wireless base station, one monitoring device, and one or more terminal devices may hereinafter be referred to as a cell. In Figure 1, each cell is surrounded by a dashed line. Also, a cell that is the object of management by the management server 1 may be referred to as a managed cell. Also, the cell under focus may be referred to as the own cell, and other cells may be referred to as other cells.

The management server 1 and the wireless base stations 2-1 and 2-2 are connected via a wired or wireless communication line 500. The communication line 500 may be, for example, the Internet, an intranet, a LAN (Local Area Network), a public telephone line network, or the like. The wireless base station 2-1 and the terminal devices 4-1 and 4-2 perform wireless communication, and the wireless base station 2-2 and the terminal devices 4-3 and 4-4 perform wireless communication. The wireless base station 2-1 and the monitor device 3-1 perform wired or wireless communication. The same is true between the wireless base station 2-2 and the monitor device 3-2. The wireless base stations 2-1 and 2-2 may be, for example, access points or other wireless base stations. The terminal devices 4-1 to 4-4 may be, for example, stations or other terminal devices. The terminal devices 4-1 to 4-4 may be, for example, personal computers, tablet terminals, smartphones, or the like. In this embodiment, the wireless communication is mainly described as wireless communication in an autonomous distributed wireless communication system. In addition, in this embodiment, the wireless communication is mainly described as a wireless LAN communication, but this is not necessarily the case. For example, ZigBee (registered trademark) communication (IEEE802.15.4) may be used. In addition, FIG. 1 shows a case where the management server 1 manages two wireless communication systems, but this is not necessarily the case. The management server 1 may manage three or more wireless communication systems. In addition, FIG. 1 shows a case where each wireless communication system includes two terminal devices, but this is not necessarily the case. As long as the wireless communication system includes one or more terminal devices, the number of terminal devices does not matter. In addition, when there is no particular need to distinguish between them, the wireless base stations 2-1 and 2-2 may be called wireless base stations 2, the monitor devices 3-1 and 3-2 may be called monitor devices 3, and the terminal devices 4-1 to 4-4 may be called terminal devices 4.

The noise source 5 is a device that emits radio waves, and may be, for example, a communication device of a managed cell, a communication device of a cell other than the managed cell, an electronic device that emits interfering radio waves such as a microwave oven, a power amplifier, or a speaker, or a collection of these.

Figure 2 is a block diagram showing the configuration of the management server 1 according to this embodiment. In Figure 2, the management server 1 manages multiple wireless communication systems, and includes a receiver 11, a memory 12, a connection destination determination unit 13, a connection destination change instruction transmission unit 14, a channel determination unit 15, a channel change instruction transmission unit 16, and a channel information transmission unit 17.

The receiving unit 11 receives information about the uncommunicated device and information about the wireless base station 2, and stores the information in the storage unit 12. The uncommunicated device is a terminal device 4 in which an uncommunicated application exists, which is an application that cannot perform wireless communication because it is not given an opportunity to communicate. Therefore, even if it is an uncommunicated device, other applications that perform wireless communication may exist. For example, wireless communication cannot be performed because wireless communication is congested and there are no wireless resources, or wireless communication may be restricted so that other applications can perform wireless communication that satisfies QoE. The terminal device 4 in which the uncommunicated application exists may be, for example, a terminal device 4 that is executing the uncommunicated application, or a terminal device 4 that wishes to execute the application. In the following description, the amount of wireless resources usually refers to the amount of wireless resources in the time direction. The amount of wireless resources may be, for example, a ratio of wireless resources in the time direction (for example, a utilization rate), a time of wireless resources per unit time (for example, a utilization time), or other information related to wireless resources in the time direction. The amount of wireless resources may also be, for example, a representative value of the amount of wireless resources. This representative value may be, for example, the average value or the median value.

The information about the uncommunicated device received by the receiving unit 11 includes an uncommunicated device identifier for identifying the uncommunicated device, the priority of the uncommunicated application in the uncommunicated device, and the required resource amount, which is the wireless resource required for wireless communication of the uncommunicated application for each wireless base station 2 to which the uncommunicated device can be connected. The uncommunicated device identifier may be, for example, the IP address and port number of the uncommunicated device, the physical address of the uncommunicated device (for example, MAC address, etc.), or other information that can identify the uncommunicated device. The priority of the application may be, for example, a numerical value (for example, an integer in the range of 0 to 10, etc.) determined for each application, or information indicating the type of application (for example, voice communication, video communication, etc.). In the latter case, it is preferable that the type of application and the priority of the application are separately associated. Specifically, the priority of the application for voice communication may be determined to be "9", and the priority of the application for video communication may be determined to be "6". In addition, since the required resource amount is information for each wireless base station 2 to which the uncommunicated device can be connected, the receiver 11 may receive, for example, information that associates a base station identifier that identifies the wireless base station 2 with the required resource amount when the uncommunicated device performs wireless communication with the wireless base station 2, and store them in the storage unit 12. The base station identifier may be, for example, the SSID (Service Set ID) of the wireless base station 2, the ESSID (Extended SSID), the BSSID (Basic Service Set ID), or other identifiers that can identify the wireless base station 2. Strictly speaking, the wireless base station 2 to which the uncommunicated device can be connected also includes the wireless base station 2 to which the uncommunicated device is currently performing wireless communication, but the required resource amount of the uncommunicated application for each wireless base station 2 to which the uncommunicated device can be connected may not include the required resource amount of the uncommunicated application of the wireless base station 2 to which the uncommunicated device is currently performing wireless communication. The receiver 11 usually receives information about the uncommunicated device from the wireless base station 2, but this is not necessary. The source of the information about the uncommunicated device may be, for example, the wireless base station 2 or the terminal device 4. The uncommunicated device identifier received by the receiver 11 may be associated with the base station identifier of the wireless base station 2 that transmitted the uncommunicated device identifier and stored in the memory 12. By using this association, it becomes possible to know with which wireless base station 2 the uncommunicated device is communicating wirelessly.

The information on the wireless base station 2 received by the receiving unit 11 includes information necessary for determining the connection destination, which will be described later, and information necessary for determining the channel. The information necessary for determining the connection destination is the amount of addable resources in the used channel for each wireless base station 2. The used channel is the channel used in the wireless communication performed by each wireless base station 2. The amount of addable resources is the wireless resources that can be added. The information necessary for determining the channel is the amount of used resources, which are the wireless resources used by a certain wireless base station 2 in each channel, and the amount of addable resources in each channel of the wireless base station 2. Note that the information necessary for determining the channel may be received only from the wireless base station 2 that is the target of the channel determination, or may not be. In the latter case, the receiving unit 11 may receive, for example, the information necessary for determining the channel from each wireless base station 2. In that case, the receiving unit 11 receives the information necessary for determining the channel, and as a result, the information necessary for determining the connection destination is also received. The receiving unit 11 may also receive the used channel for each wireless base station 2. Note that receiving the used channel may be receiving information that allows the use channel to be known as a result. For example, if the channel in use can be determined from the amount of resources used for each channel (e.g., the channel with the largest amount of resources used can be determined to be the channel in use), receiving the amount of resources used can be considered to be an indirect reception of the channel in use. Also, for example, if the amount of addable resources for the channel in use and the amount of addable resources for each channel are received separately, the amount of addable resources for the channel in use does not need to be included in the amount of addable resources for each channel.

The required resource amount received by the receiver 11 may be calculated, for example, by the wireless base station 2 or the terminal device 4, or may be calculated by another device. The amount of used resources and the amount of addable resources received by the receiver 11 may be acquired, for example, by the wireless base station 2, or may be acquired by another device. Even in the latter case, it is preferable that the acquisition be performed near the wireless base station 2.

The receiving unit 11 may also receive information transmitted from the wireless base station 2 or the like in response to a transmission request transmitted from the management server 1. The transmission request may be transmitted, for example, from the connection destination change instruction transmitting unit 14 or the channel change instruction transmitting unit 16, or may be transmitted from another transmitting unit not shown. The receiving unit 11 stores the received information in the memory unit 12. The receiving unit 11 may or may not include a wired or wireless receiving device (for example, a modem or a network card) for receiving. The receiving unit 11 may also be realized by hardware, or may be realized by software such as a driver that drives the receiving device.

The storage unit 12 stores the information received by the receiving unit 11. The storage unit 12 is preferably realized by a non-volatile recording medium, but may also be realized by a volatile recording medium. The storage unit 12 can be realized by a predetermined recording medium (e.g., a semiconductor memory, a magnetic disk, an optical disk, etc.).

The connection destination determination unit 13 determines a new connection destination wireless base station 2 for the uncommunicated device identified by the uncommunicated device identifier received by the receiving unit 11. The information used for this purpose is the following (I) and (II).
(I) Information for each uncommunicated device is as follows:
- Uncommunicated device identifier - Priority of uncommunicated application - Required resource amount for each connectable wireless base station 2 (II) Amount of addable resources in a channel in use for each wireless base station 2

The connection destination determination unit 13 determines, as a new connection destination for the uncommunicated device, a wireless base station 2 that has an addable resource amount equal to or greater than the resource amount required for the uncommunicated application in the uncommunicated device, among the wireless base stations 2 to which the uncommunicated device can be connected. Specifically, the connection destination determination unit 13 sorts the uncommunicated device identifiers in descending order of the priority of the uncommunicated application. Then, starting from the uncommunicated device identified by the first uncommunicated device identifier after sorting, the connection destination determination unit 13 determines a new connection destination in the following order. First, the connection destination determination unit 13 obtains the required resource amount for each wireless base station 2 to which the uncommunicated device, which is the target for determining a new connection destination, can connect, and the addable resource amount for each wireless base station 2. Note that the required resource amount and the like are not obtained for the wireless base station 2 with which the uncommunicated device is currently performing wireless communication. Then, the connection destination determination unit 13
It is determined whether there is a wireless base station 2 for which the amount of addable resources is equal to or greater than the amount of required resources. The amount of addable resources and the amount of required resources to be compared correspond to the same wireless base station 2. If there is only one such wireless base station 2, the connection destination determination unit 13 sets the wireless base station 2 as a new connection destination for the uncommunicated device. On the other hand, if there are two or more such wireless base stations 2, the connection destination determination unit 13 selects one wireless base station 2 to be a new connection destination from among the two or more wireless base stations 2, and sets the selected wireless base station 2 as a new connection destination for the uncommunicated device. In this selection, the connection destination determination unit 13 may, for example, select the wireless base station 2 with the smallest amount of required resources, select the wireless base station 2 with the largest amount of addable resources, select randomly, or make other selections. If the wireless base station 2 with the smallest amount of required resources is selected, the wireless resources required for wireless communication will be minimized when the uncommunicated device performs wireless communication at a new connection destination. Therefore, from the viewpoint of efficient use of wireless resources, it is preferable to select the wireless base station 2 with the smallest amount of required resources. Then, the connection destination determination unit 13 subtracts the required resource amount from the addable resource amount of the wireless base station 2 that has become the new connection destination. More precisely, the connection destination determination unit 13 identifies the required resource amount corresponding to the wireless base station 2 that has become the new connection destination from the required resource amount corresponding to the uncommunicated application in the uncommunicated device that has been determined as the new connection destination. Then, the connection destination determination unit 13 subtracts the identified required resource amount from the addable resource amount of the wireless base station 2 that has become the new connection destination. Thereafter, the connection destination determination unit 13 repeats the same process for the next uncommunicated device.

If there are two or more uncommunicated applications in the uncommunicated device for which a new connection destination is to be determined, it is preferable to perform the above-mentioned process using the total amount of resources required for the two or more uncommunicated applications. If there is an application already performing wireless communication in the uncommunicated device for which a new connection destination is to be determined, it is preferable to perform the above-mentioned process using the amount of resources required that is the result of adding the amount of resources required for that application to the amount of resources required for the uncommunicated application. In that case, after a new connection destination is determined, it is preferable for the connection destination determination unit 13 to increase the amount of addable resources of the wireless base station 2 with which the uncommunicated device was performing wireless communication by the amount of resources required for the application that was already performing wireless communication.

The connection destination change instruction transmission unit 14 transmits a connection destination change instruction to the uncommunicated device that has been determined to connect to the new connection destination, in accordance with the determination result by the connection destination determination unit 13. It is preferable that the connection destination change instruction includes the base station identifier of the wireless base station 2 that is the new connection destination. If the connection destination change instruction is ultimately received by the uncommunicated device, it may be transmitted, for example, to the uncommunicated device as the transmission destination, or may be transmitted to the wireless base station 2 that is performing wireless communication with the uncommunicated device as the transmission destination. For example, when the uncommunicated device identifier and the address of the terminal device 4 identified by the uncommunicated device identifier are associated with each other, the connection destination change instruction transmission unit 14 may transmit a connection destination change instruction to the address corresponding to the uncommunicated device identifier of the uncommunicated device that has been determined to be the new connection destination as the transmission destination. The connection destination change instruction may also include an uncommunicated device identifier that identifies the terminal device 4 (uncommunicated device) that will connect to the new wireless base station 2. In this case, the connection destination change instruction may be, for example, information that associates an uncommunicated device identifier that identifies an uncommunicated device that will connect to a new wireless base station 2 with a base station identifier that identifies a wireless base station 2 to which the uncommunicated device identified by the uncommunicated device identifier will newly connect. In this case, a single connection destination change instruction may include information about all uncommunicated devices that will change the connection destination, and the connection destination change instruction may be transmitted by broadcast.

The connection destination change instruction sending unit 14 may send the signal to an address stored in a recording medium (not shown), or may send the signal to an address received from another component or another server before sending the signal. The connection destination change instruction sending unit 14 may or may not include a sending device (such as a modem or a network card) for sending the signal. The connection destination change instruction sending unit 14 may be realized by hardware, or may be realized by software such as a driver that drives the sending device.

The channel determination unit 15 determines a new channel to be used for a wireless base station 2 that performs wireless communication with an uncommunicated device for which a new connection destination has not been determined, using the amount of resources used and the amount of resources that can be added for each channel related to the wireless base station 2, so that the amount of resources that can be added increases. When changing the channel to be used, wireless communication is temporarily interrupted, and the QoE may decrease. Therefore, if there are still uncommunicated devices even after changing the connection destination, the channel to be used is changed on a cell-by-cell basis. In addition, this change in the channel to be used is usually performed only for one cell (wireless base station 2). Therefore, if there are two or more wireless base stations 2 that perform wireless communication with an uncommunicated device for which a new connection destination has not been determined, a wireless base station 2 to be the target for changing the channel to be used may be selected from the two or more wireless base stations 2. It is necessary that the amount of resources that can be added increases at least by changing the channel to be used in the wireless base station 2 to be selected.

Here, a method for determining whether there is a new channel in use that will increase the amount of addable resources will be described. In a certain wireless base station 2, it is assumed that the amount of used resources for each channel is A(CH) and the amount of addable resources for each channel is B(CH). CH is a channel. Then, the amount of available resources is A(CH)+B(CH). Therefore, the channel determination unit 15 determines whether there is a new channel in use that will increase the amount of addable resources.
A(CH)+B(CH)>A(used CH)+B(used CH)
The "used CH" is the currently used channel. If such a channel CH exists, the channel determination unit 15 determines that the wireless base station 2 has a new used channel that increases the amount of addable resources, and may set the wireless base station 2 as a candidate wireless base station 2 for channel change. Among the channels CH that satisfy the above relationship, the channel determination unit 15 may set the channel CH with the largest A(CH)+B(CH) as the new used channel, or may set the channel CH that is farthest from the used channels of the other wireless base stations 2 as the new used channel.

Next, a method of selecting a wireless base station 2 that actually performs a channel change from among the wireless base stations 2 that are candidates for channel change will be described. The channel determination unit 15 may determine a new channel to be used for a wireless base station 2 that performs wireless communication with more uncommunicated devices for which a new connection destination has not been determined. More means more than other wireless base stations 2. For example, among the wireless base stations 2 that are candidates for channel change, a wireless base station 2 that performs wireless communication with the most uncommunicated terminals may be selected as the wireless base station 2 that performs a channel change. In addition, the channel determination unit 15 may calculate, for each wireless base station 2, a total value according to the priority of the uncommunicated application in the uncommunicated device that performs wireless communication with the wireless base station 2, and determine a new channel to be used for the wireless base station 2 with the largest total value. In other words, the wireless base station 2 that performs a channel change may be selected taking into account the priority of the uncommunicated application. The value according to the priority of the uncommunicated application is a value that increases as the priority becomes higher. The value may be, for example, the priority itself, or may be a value of an increasing function with the priority as an argument. The channel determination unit 15 may also select a wireless base station 2 that will actually perform a channel change from among the wireless base stations 2 that are channel change candidates by other methods. For example, if the management server 1 can know the uncommunicated period during which an uncommunicated application is not communicating, a wireless base station 2 that performs wireless communication with an uncommunicated device having an uncommunicated application with the longest uncommunicated period may be selected from the wireless base stations 2 that are channel change candidates. A wireless base station 2 may also be selected randomly from the wireless base stations 2 that are channel change candidates.

In the above description, the method of identifying channel change candidates and then selecting the wireless base station 2 that will actually perform the channel change has been described, but this is not essential. It may be determined whether there is a new channel in use that will increase the amount of addable resources for the wireless base stations 2 that are most likely to be selected according to the selection criteria. For example, if the selection criteria is to perform wireless communication with a larger number of uncommunicated devices, the channel determination unit 15 may determine whether there is a new channel in use that will increase the amount of addable resources for the wireless base stations 2 that perform wireless communication with uncommunicated devices for which a new connection destination has not been determined, in order of the number of uncommunicated devices, and may set the wireless base station 2 with the new channel in use as the target for channel change. In that case, for example, it may be possible to request transmission of information necessary for channel determination only for the wireless base station 2 to be determined.

The channel change instruction transmitting unit 16 transmits a channel change instruction to the wireless base station 2 for which a new channel to be used has been determined, to change the channel to be used in accordance with the result of the determination made by the channel determining unit 15. It is preferable that the channel change instruction includes the new channel to be used. The channel change instruction may also include information regarding the timing of changing the channel to be used. The information regarding the timing may be, for example, the time (period) from when the channel change instruction is received until the channel to be used is changed, or may be the time when the channel to be used is changed.

The channel change instruction transmitting unit 16 may transmit to an address stored in a recording medium (not shown) as the destination, or may transmit to an address received from another component or another server before transmission. The channel change instruction transmitting unit 16 may or may not include a transmitting device (e.g., a modem or a network card) for transmitting. The channel change instruction transmitting unit 16 may be realized by hardware, or may be realized by software such as a driver that drives the transmitting device.

The channel information transmission unit 17 transmits channel information indicating the channels used by each wireless base station 2 to the terminal device 4. The timing of the transmission does not matter, but it is preferable that the channel information is transmitted so that there is no discrepancy between the channels used indicated by the channel information received by each terminal device 4 and the actual channels used. For example, the channel information may be transmitted periodically, or when wireless communication by a new wireless base station 2 is started or when the channel used by the wireless base station 2 is changed. Note that a channel scan is performed in each terminal device 4 for the channels used indicated by the channel information. As a result, the time required for the channel scan can be shortened. Note that, since the channel information is transmitted for such a purpose, the channel information may be information on the channels used by the wireless base station 2 within the range of radio waves (the range in which radio waves may interfere). For example, when a wireless communication system in a very wide area is managed by the management server 1, each wireless communication system may be grouped according to the range of radio waves, and channel information may be transmitted for each group. As long as the channel information is ultimately received by each terminal device 4, it may be transmitted, for example, to each terminal device 4 as the destination, to a wireless base station 2 that is wirelessly communicating with each terminal device 4 as the destination, or it may be transmitted by broadcast.

The channel information transmitting unit 17 may transmit to an address stored in a recording medium (not shown) as the destination, or may transmit to an address received from another component or another server before transmission. The channel information transmitting unit 17 may or may not include a transmitting device (e.g., a modem or a network card) for transmitting. The channel information transmitting unit 17 may be realized by hardware, or may be realized by software such as a driver that drives the transmitting device.

Fig. 3 is a block diagram showing the configuration of a wireless base station 2 according to this embodiment. In Fig. 3, the wireless base station 2 communicates with the management server 1 via a communication line 500, receives a representative value of interference power less than the carrier sense threshold from the monitor device 3, and also wirelessly communicates with the terminal device 4, and includes a wireless communication unit 21, a communication unit 22, a control unit 23, a required resource acquisition unit 24, a used resource acquisition unit 25, and an addable resource acquisition unit 26. Note that the interference power refers to the received power of an interfering radio wave that causes a disruption to wireless communication.

The wireless communication unit 21 performs wireless communication with the terminal device 4. In addition, when a representative value of interference power less than the carrier sense threshold is transmitted from the monitor device 3 by wireless communication, the wireless communication unit 21 may receive the representative value. In addition, the representative value of interference power less than the carrier sense threshold may be transmitted by the wireless communication unit 21 to each terminal device 4 in the own cell. The transmission of the representative value to each terminal device 4 may be performed by broadcast, for example. Note that the wireless communication unit 21 may or may not include a wireless communication device for performing communication. In addition, the wireless communication unit 21 may be realized by hardware, or may be realized by software such as a driver that drives a communication device.

The communication unit 22 communicates with the management server 1 via the communication line 500. Furthermore, when a representative value of interference power less than the carrier sense threshold is transmitted from the monitor device 3 via the communication line 500, the communication unit 22 may receive the representative value. Note that the communication unit 22 may or may not include a wired or wireless communication device for communication. Furthermore, the communication unit 22 may be realized by hardware, or may be realized by software such as a driver that drives the communication device.

The control unit 23 controls the wireless communication unit 21 and the communication unit 22. For example, when the communication unit 22 receives data destined for a terminal device 4 in the LAN, the control unit 23 may control the data to be transmitted to the terminal device 4 via the wireless communication unit 21. Also, when the wireless communication unit 21 receives data destined for a device in the WAN, the control unit 23 may control the data to be transmitted to the device destined for the destination via the communication unit 22. Also, the control unit 23 controls the transmission by the wireless communication unit 21 according to the result of carrier sense using the wireless communication unit 21. Specifically, the control unit 23 may determine whether wireless communication is being performed on the transmission path according to the result of carrier sense, and control the wireless communication unit 21 to perform transmission when wireless communication is not being performed. The control by the control unit 23 may be, for example, CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) control or CSMA/CD (Carrier Sense Multiple Access/Collision Detection) control. In this embodiment, the former case will be mainly described. Note that controlling communications based on the results of carrier sensing is already well known, so a detailed explanation will be omitted.

The control unit 23 may also control the reception from the monitoring device 3 of a representative value of interference power less than the carrier sense threshold. For example, the control unit 23 may transmit a transmission request for a representative value to the monitoring device 3 at predetermined intervals, and receive a representative value from the monitoring device 3 in response. The transmission of the transmission request and the reception of the representative value may be performed via the wireless communication unit 21 or the communication unit 22, or the control unit 23 may directly perform the transmission via a predetermined interface.

When the wireless communication unit 21 receives the transmission rate for each connectable wireless base station 2 acquired by the terminal device 4 that is an uncommunicated device, or the offered load or average packet size of the uncommunicated application in the terminal device 4, the required resource acquisition unit 24 acquires the required resource amount for each connectable wireless base station 2 by using the transmission rate, etc. The offered load is the amount of traffic that the device performing wireless communication actually attempts to transmit, and may be considered to be, for example, the requested data rate of the application layer. For example, if an application requests wireless communication at 10 Mbps, the offered load is "10 Mbps". The required resource acquisition unit 24 may perform, for example, a process of acquiring the required resource amount for each connectable wireless base station 2 for all uncommunicated devices with which the wireless communication unit 21 performs wireless communication. The process of acquiring the required resources by the required resource acquisition unit 24 is described in the above-mentioned Patent Document 1, and a detailed description thereof will be omitted. The required resource amount is transmitted to the management server 1 via the communication unit 22.

The utilization resource acquisition unit 25 acquires the utilization resource amount for each channel of the wireless base station 2. The process of acquiring the utilization resource amount by the utilization resource acquisition unit 25 is described in the above-mentioned Patent Document 1, and a detailed description thereof will be omitted. The utilization resource amount is transmitted to the management server 1 via the communication unit 22.

The addable resource acquisition unit 26 acquires the amount of addable resources for the used channel of the wireless base station 2 using the amount of used resources for the used channel acquired by the used resource acquisition unit 25. This acquisition may be performed, for example, to determine a new connection destination for the uncommunicated device. The addable resource acquisition unit 26 also acquires the amount of addable resources for each channel of the wireless base station 2 using the amount of used resources for each channel acquired by the used resource acquisition unit 25. This acquisition may be performed, for example, to determine a new used channel for the wireless base station 2. As described above, when the amount of addable resources for each channel of the wireless base station 2 is acquired, the amount of addable resources for the used channel is also acquired. Therefore, the addable resource acquisition unit 26 may only acquire the amount of addable resources for each channel of the wireless base station 2. The process of acquiring the amount of addable resources by the addable resource acquisition unit 26 is described in the above-mentioned Patent Document 1, and detailed description thereof will be omitted. It is assumed that the amount of addable resources is transmitted to the management server 1 via the communication unit 22.

Figure 4 is a block diagram showing the configuration of the monitor device 3 according to this embodiment. In Figure 4, the monitor device 3 includes a receiving unit 31, a creating unit 32, a storage unit 33, an acquiring unit 34, and a transmitting unit 35.

The receiving unit 31 receives radio waves and acquires the reception power of the received radio waves. It is preferable that the radio waves received by the receiving unit 31 include at least radio waves from the noise source 5. The received radio waves may also include radio waves of a radio signal used in wireless communication. The receiving unit 31 may acquire the reception power, for example, at a predetermined sampling interval. It is also preferable that the receiving unit 31 acquires the reception power for each of all channels that can be selected in wireless communication. The receiving unit 31 may or may not include a wireless receiving device for receiving. The receiving unit 31 may be realized by hardware, or may be realized by software such as a driver that drives the receiving device.

The creation unit 32 creates a histogram of the received power for each predetermined power width using the received power acquired by the receiving unit 31 at a predetermined sampling interval during the measurement period. The measurement period is preferably set to a length that allows interference power from the noise source 5 to be sufficiently observed, and may be, for example, about 30 seconds, about 1 minute, or about several minutes. For example, the same measurement period may be used in each cell. The sampling interval is preferably short so that the received power of radio waves with short transmission periods can also be acquired. For example, the sampling interval may be 10 (μs) or 20 (μs). The measurement period may be set, for example, in the monitor device 3, or at least one of the start and end of the measurement period may be specified by another device, etc. In the latter case, the measurement may be started or ended in response to, for example, a measurement start request or a measurement end request.

As shown in FIG. 10, when the measurement start time of the measurement period is T _sta and the measurement end time is T _end , for example, the receiving unit 31 acquires the received power at each predetermined sampling interval during the period from the measurement start time T _sta to the measurement end time T _end . For example, when a radio wave of a wireless frame or an interference radio wave is received, the received power is acquired accordingly. Then, when the received power acquired in a certain sampling is RP1, the creation unit 32 increments the number (frequency) of the power bin including the received power "RP1" by 1 in the histogram of the received power. By performing such processing at each sampling interval during the measurement period, a histogram of the received power is created. Note that the histogram of the received power is a histogram that indicates the number (frequency) of detections of the received power for each power bin of a predetermined power width. In addition, the creation unit 32 may create a histogram for each channel used in wireless communication within the cell. Fig. 11A is a diagram showing an example of a histogram H _all,i,j (x) of the received power of the jth channel acquired by a monitoring device 3 included in the ith managed cell. Note that in Fig. 11A, the values of each power bin are shown as dots for convenience of explanation, but strictly speaking, they are step functions. The created histogram may be stored in the storage unit 33. For the creation of this histogram, please refer to the following literature, for example.
Reference: Satoshi Shimizu, Makoto Usui, Susumu Ano, Takuya Kurihara, Kazuto Yano, Yoshinori Suzuki, "Measurement results of radio wave environment and development of a new measuring device for it - Radio wave environment monitoring device "Radio Catcher"-", IEICE Technical Report, RCS2019-398, pp. 389-392, March 2019.

The storage unit 33 stores the histogram of received power created by the creation unit 32. As described above, this histogram may be a histogram for each selectable channel. The storage unit 33 is preferably realized by a non-volatile recording medium, but may also be realized by a volatile recording medium. The recording medium may be, for example, a semiconductor memory, a magnetic disk, an optical disk, etc.

The acquisition unit 34 acquires a representative value of interference power less than the carrier sense threshold using the histogram of the received power created by the creation unit 32. The acquisition unit 34 may acquire this representative value for each channel. The representative value of interference power less than the carrier sense threshold is a representative value of received power that is equal to or greater than the noise floor and less than the carrier sense threshold. The noise floor may be set to a value measured by the monitor device 3 having the acquisition unit 34 (e.g., -100.0 (dBm)). The carrier sense threshold may be set to a value determined by the wireless communication standard, or may be set to the minimum RSSI value among the frames received by the wireless base station 2 of the same cell as the monitor device 3 (e.g., -74.0 (dBm)). The representative value may be, for example, an average value, or may be a value of received power at which the cumulative probability of the probability density function of the histogram is a predetermined value. The cumulative probability may be, for example, the value of the cumulative distribution function (CDF) or the value of the complementary cumulative distribution function (CCDF).

When the representative value is set to the average value, there is an advantage in that the processing load for obtaining the representative value is reduced. Furthermore, when there is a power peak in the average value, wireless communication can be realized with approximately a predetermined error rate by performing wireless communication at a transmission rate obtained as described below using the representative value that is the average value. Note that the predetermined error rate is the predetermined error rate used in obtaining the transmission rate correspondence information that is described below. On the other hand, when the power peaks are separated into multiple locations, there is a possibility that interference power stronger than the average value will be applied to the receiver, and performing wireless communication at a transmission rate obtained using the representative value that is the average value may result in an error rate higher than the predetermined error rate.

When the representative value is set to the value of the received power at which the cumulative probability of the probability density function of the histogram is a predetermined value, the transmission rate is set based on the probability of causing an outage of the required SINR, i.e., the tolerable error rate, and therefore, compared to the case where the average value is used as the representative value, there is an advantage in that the possibility of unexpected deterioration in communication quality can be reduced. Note that, for example, when the cumulative probability is a CDF value, the predetermined value is preferably set to a large value of 50% or more, and when the cumulative probability is a CCDF value, it is preferably set to a small value of 50% or less. More specifically, in a system in which a communication error can be a fatal problem, such as for medical or industrial use, the predetermined value may be 80% or 90% when the cumulative probability is a CDF value, or 20% or 10% when the cumulative probability is a CCDF value. On the other hand, in a system in which a certain degree of communication error is tolerable, such as a public wireless LAN, the predetermined value may be 50% or more, whether the cumulative probability is a CDF value or a CCDF value.

In order to obtain a representative value of the interference power less than the carrier sense threshold, the obtaining unit 34 may first obtain a probability density function of the received power from the histogram of the received power. Specifically, the probability density function F _all,i,j (x) of the received power for the jth channel of the i-th managed cell may be calculated as follows using the histogram H _all,i,j (x) of the received power for the jth channel of the i-th managed cell. Here, N _bin ^total is the total number of power bins in the histogram H _all,i,j (x). That is, the identifier k of the power bin can take an integer from 0 to N _bin ^tolal -1. Moreover, x _base is the minimum value of the obtained received power. This minimum value may be a common value for each cell and each channel. Moreover, W _bin is the power bin width (dB).

Next, the acquisition unit 34 may use the probability density function of the received power to acquire a probability density function of the received power that is equal to or higher than the noise floor and lower than the carrier sense threshold, i.e., a probability density function of the interference power that is lower than the carrier sense threshold. Specifically, the probability density function F _intf,i,j (x) of the received power that is equal to or higher than the noise floor and lower than the carrier sense threshold for the jth channel of the ith managed cell may be calculated as follows using the probability density function F _all,i,j (x) of the received power for the jth channel of the ith managed cell. Here, x _lower,i <x<x _upper,i . Also, x _lower,i is the noise floor of the ith managed cell, x _upper,i is the carrier sense threshold of the ith managed cell, and N _bin is the number of power bins from x _lower,i to x _upper,i . This probability density function F _intf,i,j (x) is obtained by normalizing the probability density function F _all,i,j (x) in the range from x _lower,i to x _upper,i excluding the shaded portion in FIG. 11B.

When the representative value is an average value, the acquisition unit 34 may calculate an average value P ave,i,j of the probability density function F _intf,i,j (x) of the received power that is equal to or greater than the noise floor and less than the carrier sense threshold for the _j -th channel of the i-th managed cell as follows: This average value is an average value in the decibel domain.

When the representative value is a received power for which the cumulative probability of a probability density function obtained from a histogram of received power in a range that is equal to or greater than the noise floor and less than the carrier sense threshold is a predetermined value, the acquisition unit 34 acquires a complementary cumulative distribution function G _{intf,i,j (x) of the probability density function F intf,i,j (} x) of received power that is equal to or greater than the noise floor and less than the carrier sense threshold for the j-th channel of the i-th managed cell, as shown in the following equation. Here, the case is shown where the cumulative probability is the value of the complementary cumulative distribution function. Note that k _upper = floor ((x - x _lower ) / W _bin ), where floor is a floor function.

The complementary cumulative distribution function G _intf,i,j (x) is, for example, as shown in FIG. 11C. Then, the acquisition unit 34 acquires a representative value P _α,i,j which is x at which the cumulative probability, which is the value of the complementary cumulative distribution function G _intf,i,j (x), becomes a predetermined value α. In FIG. 11C, α is set to 0.15 (15%). Note that, strictly speaking, the complementary cumulative distribution function G _intf,i,j (x) is a discrete value, so the acquisition unit 34 may first obtain k _α,i,j which is the value of k at which the complementary cumulative distribution function G _intf,i,j (x) becomes the maximum value within a range equal to or less than the predetermined value α, as shown in the following formula. Here, Z is an integer equal to or greater than 0.

The acquisition unit 34 can acquire a representative value P _α,i,j, which is the value of x at which the complementary cumulative distribution function G _intf,i,j (x) is maximum within a range equal to or less than a predetermined value α, by substituting k _α,i,j obtained by the above formula into the following formula. This representative value P _α,i,j is the value of the received power at which the cumulative probability of the probability density function of the histogram is a predetermined value. Since the cumulative probability of the probability density function of the histogram is a discrete value in the strict sense, this representative value may be the value of the received power closest to α within a range in which the cumulative probability of the probability density function of the histogram is equal to or less than α (in the case of CCDF), or may be the value of the received power closest to α within a range in which the cumulative probability of the probability density function of the histogram is equal to or more than α (in the case of CDF).

Here, the cumulative probability is the CCDF value, so strictly speaking, the cumulative probability is the upper cumulative probability. On the other hand, even if the CDF value is used as the cumulative probability, it is possible to obtain a representative value, which is the value of the received power at which the cumulative probability of the histogram probability density function becomes a predetermined value, in a similar manner.

The transmitter 35 transmits the representative value acquired by the acquirer 34. The representative value to be transmitted may be a representative value for each channel. The final destination of the representative value is each terminal device 4 included in the same cell as the monitor device 3. The transmitter 35 may transmit the representative value to each terminal device 4 via the wireless base station 2, for example, may transmit the representative value directly to each terminal device 4, or may transmit the representative value to each terminal device 4 via other devices. When transmitting the representative value directly to each terminal device 4, the transmitter 35 may transmit the representative value by broadcasting or the like together with the base station identifier of the wireless base station 2 of its own cell, for example, so that it is possible to know which cell the representative value is. In this embodiment, the case where the transmitter 35 transmits the representative value to each terminal device 4 via the wireless base station 2 will be mainly described. The representative value may be transmitted from the transmitter 35 to the wireless base station 2 by wire or wirelessly. In this embodiment, the case where the representative value is transmitted to the wireless base station 2 by wire will be mainly described. Furthermore, the transmitter 35 may transmit the representative value in response to receiving a request to transmit the representative value from the wireless base station 2, or may transmit the representative value at regular or irregular time intervals. In the former case, for example, a transmission request may be received by any of the components of the monitor device 3, and the representative value may be transmitted in response to the request.

The transmitting unit 35 may or may not include a transmitting device (e.g., a modem or a network card) for transmitting. The transmitting unit 35 may be realized by hardware, or may be realized by software such as a driver that drives the transmitting device.

In addition, in this embodiment, the case where the wireless base station 2 and the monitor device 3 are separate devices are shown, but this is not necessary. All or part of the monitor device 3 may be present in the wireless base station 2. When the entire monitor device 3 is included in the wireless base station 2, the same processing as that of the monitor device 3 is performed in the wireless base station 2. Also, when a part of the monitor device 3 is included in the wireless base station 2, for example, the acquisition processing of the representative value and the transmission processing of the representative value may be performed in the wireless base station 2. In this case, the acquisition unit 34 and the transmission unit 35 are included in the wireless base station 2. Also, for example, the transmission processing of the representative value may be performed in the wireless base station 2. In this case, the transmission unit 35 is included in the wireless base station 2. In this way, each process and each function of the monitor device 3 may be realized by a single device, or may be realized by distributed processing by multiple devices. In this embodiment, the case where the wireless base station 2 and the monitor device 3 are separate devices and the representative value transmitted by the transmission unit 35 is transmitted to each terminal device 4 via the wireless base station 2 will be mainly described. Even if the wireless base station 2 and the monitor device 3 are separate devices, it is preferable that the monitor device 3 be placed near the wireless base station 2. This is because it is preferable that the representative value of the interference power below the carrier sense threshold acquired by the monitor device 3 is essentially the representative value of the interference power below the carrier sense threshold at the position of the wireless base station 2.

Fig. 5 is a block diagram showing the configuration of a terminal device 4 according to this embodiment. In Fig. 5, the terminal device 4 wirelessly communicates with the wireless base station 2, and includes a wireless communication unit 41, a control unit 42, a storage unit 43, a calculation unit 44, a transmission rate acquisition unit 45, and a processing unit 46.

The wireless communication unit 41 performs wireless communication with the wireless base station 2. The wireless communication unit 41 may transmit, for example, the transmission rate for each wireless base station 2, the priority of the uncommunicated application, the offered load, the average packet size, and the like acquired by the transmission rate acquisition unit 45, to the wireless base station 2 with which the wireless communication is being performed. As described above, the offered load and the average packet size are used in calculating the required resource amount. The wireless communication unit 41 may also receive a connection destination change instruction, a channel change instruction, and channel information transmitted from the management server 1 via the wireless base station 2. The wireless communication unit 41 also receives a representative value of interference power less than the carrier sense threshold. The representative value is transmitted from the monitor device 3. The wireless communication unit 41 may receive, for example, the representative value via the wireless base station 2, or may receive the representative value directly from the monitor device 3. The representative value received by the wireless communication unit 41 may be, for example, a representative value for each channel of wireless communication. The received representative value may be stored in the storage unit 43. The wireless communication unit 41 may or may not include a wireless communication device for performing communication. The wireless communication unit 41 may be realized by hardware or by software such as a driver that drives a communication device.

The control unit 42 controls the wireless communication unit 41. For example, when there is data to be transmitted, the control unit 42 may control the data to be transmitted via the wireless communication unit 41. Also, for example, when the wireless communication unit 41 receives data from the wireless base station 2, the control unit 42 may pass the data to the processing unit 46. Also, for example, when the wireless communication unit 41 receives a connection destination change instruction, the control unit 42 may control the wireless base station 2 to which the wireless communication unit 41 is connected to change in response to the connection destination change instruction. Also, for example, when the wireless communication unit 41 receives a channel change instruction, the control unit 42 may control the wireless communication unit 41 to change the channel used in wireless communication with the wireless base station 2 in response to the channel change instruction. Also, like the control unit 23, the control unit 42 controls the transmission by the wireless communication unit 41 in response to the result of carrier sense using the wireless communication unit 41. Also, when the wireless communication unit 41 receives channel information, the control unit 42 may scan only the used channel indicated by the channel information in the subsequent channel scan. By doing so, the time required for channel scanning can be shortened. In addition, if channel information is received multiple times, it is preferable to perform a channel scan using the most recent channel information.

The received representative value may be stored in the storage unit 43. The representative value may be stored for each channel. Furthermore, since the representative value is usually received repeatedly, the representative value may be stored in the storage unit 43 so that the order in which it was received can be determined. The storage unit 43 is preferably realized by a non-volatile recording medium, but may also be realized by a volatile recording medium. The recording medium may be, for example, a semiconductor memory or a magnetic disk.

The calculation unit 44 calculates a signal-to-interference-and-noise ratio (SINR) using the representative value of the interference power and the reception strength of the radio signal transmitted from the radio base station 2. The reception strength may be, for example, a received signal strength indicator (RSSI). Specifically, the calculation unit 44 calculates a signal-to-interference-and-noise ratio SINR _m,n in a link between the m-th radio base station 2 and the own device, which is the n-th terminal device 4, as shown in the following formula. Note that the calculation unit 44 may calculate the SINR for each channel, for example, or may calculate the SINR only for the channel for which the transmission rate is acquired by the transmission rate acquisition unit 45. The calculation unit 44 may also calculate the SINR for each radio base station 2 to which the terminal device 4, which is the own device, can be connected. The calculation unit 44 may calculate the SINR for the radio base station 2 of the own cell, for example, or may calculate the SINR for the radio base station 2 of another cell.

In addition, P ^RSSI _m,n is the RSSI (dBm) of the frame transmitted by the m-th wireless base station 2 and received by the n-th terminal device 4. For example, the RSSI of the beacon transmitted from the wireless base station 2 may be acquired. The RSSI may be acquired by, for example, the wireless communication unit 41. In addition, P ^INTF _m is a representative value of the interference power less than the carrier sense threshold acquired by the monitor device 3 of the cell including the m-th wireless base station 2. This representative value may be, for example, the latest representative value, or may be the average of the latest representative values of a predetermined number (for example, two or three). In addition, P ^NT _n is the thermal noise (dBm) of the n-th terminal device 4. For example, the actual measured value of the terminal device 4 may be used for this thermal noise, or it may be calculated based on the configuration of the receiver of the terminal device 4. In the case of actual measurement, for example, in an environment where only the noise floor of the receiver can be observed, such as an anechoic chamber, the thermal noise may be acquired by measuring the average power in the reception bandwidth using a measuring device such as a spectrum analyzer. Furthermore, when the calculation is based on the configuration of the receiver of the terminal device 4, the calculation may be performed using the following formula.

Here, k·T, B, and NF are as follows:
k・T=1.3803× ^10-23 ×290.0×1000(mW/Hz)
B: Reception bandwidth (Hz)
NF: Receiver noise figure (dB)

When there is an uncommunicated application that is an application that cannot perform wireless communication, the transmission rate acquisition unit 45 acquires a transmission rate for each connectable wireless base station 2. The transmission rate acquisition unit 45 may also acquire a transmission rate between the wireless base station 2 of the own cell. The transmission rate acquisition unit 45 may acquire a transmission rate of a channel used in a later process such as acquisition of a required resource amount. Specifically, the transmission rate acquisition unit 45 may acquire a transmission rate of a channel used. The transmission rate acquisition unit 45 acquires a transmission rate corresponding to the SINR calculated by the calculation unit 44 using transmission rate correspondence information that associates the SINR with the transmission rate. For example, when the transmission rate correspondence information shown in FIG. 12 is stored in a recording medium (not shown), the transmission rate acquisition unit 45 may acquire a transmission rate associated with the signal-to-interference-and-noise ratio SINR _m,n calculated by the calculation unit 44 by the transmission rate correspondence information. When the transmission rate is acquired using the transmission rate correspondence information of FIG. 12, for example, a transmission rate of "13.0 (Mbps)" may be acquired for an SINR of "12 (dB)" acquired for a certain wireless base station 2. The transmission rate correspondence information may be, for example, information having two or more pairs of SINR and transmission rate as shown in FIG. 12. The transmission rate may be acquired by acquiring an MCS (Modulation and Coding Scheme) index. A method for creating the transmission rate correspondence information will be described later. Strictly speaking, this transmission rate is a downstream transmission rate. Therefore, the upstream transmission rate may be estimated using the downstream transmission rate. The upstream transmission rate may be estimated by, for example, adding a predetermined offset to the downstream transmission rate, or may be estimated using the downstream RSSI obtained by adding a predetermined offset. The offset may be a positive value, a negative value, or 0. It is preferable that the offset value is set in consideration of the characteristics of each terminal device 4. For example, for a terminal device 4 that is expected to transmit with a greater transmission power than the wireless base station 2, the offset may be a positive value, and for a terminal device 4 that is expected to transmit with a lesser transmission power than the wireless base station 2, the offset may be a negative value.

The transmission rate between the wireless base station 2 of the other cell acquired by the transmission rate acquisition unit 45 may be transmitted to the wireless base station 2 via the wireless communication unit 41. Also, for example, when the wireless base station 2 to which the terminal device 4 is connected is changed, wireless communication with the wireless base station 2 may be performed using the transmission rate acquired for the changed wireless base station 2. The transmission rate may be set, for example, by the terminal device 4 or by the management server 1. In the latter case, the transmission rate between the wireless base station 2 and the terminal device 4 may be transmitted from the wireless base station 2 to the management server 1 in association with the base station identifier of the wireless base station 2 and the identifier of the terminal device 4. Also, wireless communication between the terminal device 4 and the wireless base station 2 may be performed using the transmission rate between the wireless base station 2 of the own cell acquired by the transmission rate acquisition unit 45. Therefore, for example, the wireless communication unit 41 may perform wireless communication using the transmission rate of its own cell, or may transmit the transmission rate of its own cell to the wireless base station 2 of its own cell so that wireless communication using that transmission rate is performed.

The processing unit 46 performs processing related to the received information and the information to be transmitted. The processing may be application processing. The processing unit 46 may perform the processing for each application. For example, when voice communication is being performed, the processing unit 46 may accumulate packets corresponding to the audio signal in a transmission queue (not shown), or receive packets corresponding to the voice communication received by the wireless communication unit 41, and perform application processing related to the voice communication.

In the present embodiment, the case will be described where the terminal device 4 acquires the transmission rate and the wireless base station 2 acquires the required resource amount using the transmission rate, but this is not necessarily the case. For example, the terminal device 4 may acquire the transmission rate and the required resource amount using the transmission rate. That is, the information transmitted from the terminal device 4 to the wireless base station 2 may be information that can ultimately acquire the required resource amount, and specifically, may be the transmission rate or the required resource amount itself. Therefore, the wireless communication unit 41 may be considered to transmit information to the wireless base station 2 that enables the wireless base station 2 that wirelessly communicates with the terminal device 4 to transmit the required resource amount for each wireless base station 2 to which the terminal device 4 can be connected, which is calculated according to the transmission rate, to the management server 1.

Here, a method for creating transmission rate correspondence information is described. A system capable of simultaneously receiving a radio signal transmitted at a predetermined transmission rate and power and an interference signal applied at a predetermined power is constructed by using an actual device or a simulation. Then, the transmission rate and the power of the transmission signal are constant, the SINR is calculated, and the error rate of the received signal is measured. Note that, if the RSSI and transmission rate are constant, the error rate increases as the interference noise power increases. Therefore, the measurement is repeated while increasing the power of the interference signal until the error rate exceeds a predetermined error rate that is arbitrarily set. Finally, the minimum SINR that is equal to or lower than the predetermined error rate is identified. If communication is performed with an SINR equal to or higher than this minimum SINR, wireless communication with a predetermined error rate or lower can be realized, and this minimum SINR becomes the lower limit of the SINR corresponding to the transmission rate at that time. By performing such processing while changing the predetermined transmission rate, the lower limit of the SINR can be associated with the transmission rate.

In addition, from the viewpoint of effective use of wireless resources, it is preferable to perform communication at a higher transmission rate. Therefore, as the upper limit of the SINR corresponding to a certain transmission rate, the lower limit of the SINR corresponding to a transmission rate higher than that transmission rate may be set. Therefore, for example, if the lower limit SINR corresponding to MCS=1 (transmission rate: 13.0 Mbps) is 10 (dB) and the lower limit SINR corresponding to MCS=2 (transmission rate: 19.5 Mbps) is 15 (dB), the SINR corresponding to MCS=1 may be 10 (dB) or more and less than 15 (dB), as shown in FIG. 12. Note that the transmission rate correspondence information may be, for example, information in a table format as shown in FIG. 12, or may be information in another format.

The predetermined error rate used when generating the transmission rate correspondence information is preferably set so as to satisfy the required QoE of the network. By doing so, when wireless communication is performed at a transmission rate corresponding to the SINR calculated by the calculation unit 44, wireless communication with an error rate equal to or lower than the predetermined error rate can be realized, and the required QoE of the network is satisfied. In other words, the transmission rate correspondence information may be considered as information that associates the SINR with a transmission rate for realizing wireless communication with an error rate equal to or lower than the predetermined error rate in the SINR environment. In addition, the same transmission rate correspondence information may be used for the same wireless communication system. For example, when Wi-Fi (registered trademark) wireless communication is performed in each managed cell, the transmission rate correspondence information acquired for the Wi-Fi wireless communication system may be used in the terminal device 4 of each managed cell.

Next, the operation of the management server 1 will be described with reference to the flowchart of FIG. 6A.
(Step S101) A transmitting unit (not shown) of the management server 1 judges whether it is time to transmit a transmission request for requesting transmission of a required resource amount, etc. If it is time to transmit a transmission request, the process proceeds to step S102, and if not, the process of step S101 is repeated until it is determined to transmit a transmission request. Note that the transmitting unit may, for example, periodically determine to transmit a transmission request, or may determine to transmit a transmission request when a decrease in QoE is detected.

(Step S102) The transmitting unit (not shown) transmits a transmission request to each wireless base station 2.

(Step S103) In response to the transmission of the transmission request, the receiver 11 determines whether or not information has been received from the wireless base station 2. If information has been received, the process proceeds to step S104; if not, the process proceeds to step S105.

(Step S104) The receiving unit 11 stores the received information in the memory unit 12.

(Step S105) The connection destination determination unit 13 determines whether to end the reception process. If the reception process is to be ended, the process proceeds to step S106. If not, the process returns to step S103. Note that the connection destination determination unit 13 may determine to end the reception process, for example, when a predetermined time has elapsed since the transmission request was sent, or may determine to end the reception process when information has been received from all wireless base stations 2.

(Step S106) The connection destination determination unit 13 performs a process to determine a wireless base station 2 that is a new connection destination for the uncommunicated device. Details of this process will be described later using the flowchart in FIG. 6B.

(Step S107) After the processing of step S106, the channel determination unit 15 determines whether there is an uncommunicated device for which a new connection destination has not been determined. If there is such an uncommunicated device, the process proceeds to step S108; if not, the process proceeds to step S109.

(Step S108) The channel determination unit 15 performs a process of determining a new channel to be used for the wireless base station 2 that performs wireless communication with an uncommunicated device for which a new connection destination has not been determined. Details of this process will be described later using the flowchart in FIG. 6C.

(Step S109) The channel information transmitting unit 17 transmits, to each wireless base station 2, channel information indicating the channels being used by each wireless base station 2 at that time. Then, the process returns to step S101.
In the flowchart of FIG. 6A, the process ends when the power is turned off or an interrupt occurs to end the process.

Figure 6B is a flowchart showing the details of the process (step S106) of determining a wireless base station 2 to which an uncommunicated device is to be newly connected in the flowchart of Figure 6A.

(Step S201) The connection destination determination unit 13 sorts the uncommunicated device identifiers received by the receiving unit 11 in descending order of priority of the uncommunicated applications corresponding to the uncommunicated device identifiers.

(Step S202) The connection destination determination unit 13 sets counter i to 1.

(Step S203) The connection destination determination unit 13 determines whether or not there is a wireless base station 2 that can be connected to the uncommunicated device identified by the i-th uncommunicated device identifier after sorting (hereinafter, also referred to as the "i-th uncommunicated device"), and that has an addable resource amount of the channel in use that is equal to or greater than the required resource amount. If such a wireless base station 2 is present, the process proceeds to step S204, and if not, the process proceeds to step S207.

(Step S204) If there are two or more wireless base stations 2 whose available resource amount for the channel in use is equal to or greater than the required resource amount, the connection destination determination unit 13 determines the wireless base station 2 whose required resource amount is the smallest as the new connection destination for the i-th uncommunicated device. Note that if there is only one wireless base station 2 whose available resource amount for the channel in use is equal to or greater than the required resource amount, that wireless base station 2 is determined as the new connection destination for the i-th uncommunicated device.

(Step S205) The connection destination change instruction transmission unit 14 transmits a connection destination change instruction to the i-th uncommunicated device to change the connection destination to the wireless base station 2, which is the new connection destination.

(Step S206) The connection destination determination unit 13 subtracts the amount of resources required when the i-th uncommunicated device connects to the wireless base station 2 from the amount of addable resources of the wireless base station 2 that has become the new connection destination.

(Step S207) The connection destination determination unit 13 increments the counter i by 1.

(Step S208) The connection destination determination unit 13 determines whether the i-th uncommunicated device exists. If the i-th uncommunicated device exists, the process returns to step S203. If not, the process returns to the flowchart in FIG. 6A.

Figure 6C is a flowchart showing the details of the process of determining a new channel to be used (step S108) in the flowchart of Figure 6A.

(Step S301) The channel determination unit 15 sorts the base station identifiers of the wireless base stations 2 that are performing wireless communication with the uncommunicated devices whose connection destinations have not been changed, in descending order of the number of uncommunicated devices performing wireless communication with the wireless base station 2.

(Step S302) The channel determination unit 15 sets counter j to 1.

(Step S303) The channel determination unit 15 determines whether the channel used by the wireless base station 2 identified by the jth base station identifier after sorting (hereinafter, also referred to as the "jth wireless base station 2") can be changed, using the amount of used resources and the amount of addable resources for each channel corresponding to the jth wireless base station 2. If the channel used can be changed, the process proceeds to step S304, and if not, the process proceeds to step S306.

(Step S304) The channel determination unit 15 determines a new channel to be used for the j-th wireless base station 2.

(Step S305) The channel change instruction transmitter 16 transmits a channel change instruction to the j-th wireless base station 2 to change the channel in use to the channel in use determined in step S304. Then, the process returns to the flowchart in FIG. 6A.

(Step S306) The channel determination unit 15 increments the counter j by 1.

(Step S307) The channel determination unit 15 determines whether the jth wireless base station 2 exists. If the jth wireless base station 2 exists, the process returns to step S303. If not, the process returns to the flowchart in FIG. 6A.

Note that the flowchart in FIG. 6C shows the process of changing the channel used by the wireless base station 2 that performs wireless communication with a larger number of uncommunicated devices, but as mentioned above, the wireless base station 2 that changes the channel used may be determined based on other criteria.

Next, the operation of the wireless base station 2 will be described with reference to the flowchart of FIG.
(Step S401) The control unit 23 starts a timer for controlling the transmission timing of the representative value to start timing. The timer may be set to, for example, about 5 minutes or 10 minutes. At each time the timer is set, the representative value is transmitted to each terminal device 4 in each cell.

(Step S402) The control unit 23 determines whether the timer has expired. If the timer has expired, the process proceeds to step S403. If not, the process proceeds to step S405.

(Step S403) The control unit 23 sends a request to send the representative value to the monitor device 3.

(Step S404) The control unit 23 resets the timer and starts a new count. Then, the process returns to step S402.

(Step S405) The control unit 23 determines whether or not a representative value transmitted from the monitor device 3 has been received. If so, the process proceeds to step S406; if not, the process proceeds to step S407.

(Step S406) The control unit 23 transmits the received representative value to each terminal device 4 via the wireless communication unit 21. This transmission may be performed, for example, by broadcast. Then, the process returns to step S402.

(Step S407) The communication unit 22 determines whether or not a transmission request for the required amount of resources has been received. If a transmission request has been received, the process proceeds to step S408. If not, the process proceeds to step S411. Note that examples of items that the communication unit 22 may receive include a transmission request for the required amount of resources, a connection destination change instruction, a channel change instruction, channel information, etc.

(Step S408) The wireless communication unit 21 transmits the transmission request etc. received in step S407 to the terminal device 4 with which it is wirelessly communicating. Note that if the destination of the information to be transmitted is specified, it may be transmitted only to the destination terminal device 4.

(Step S409) The control unit 23 determines whether the information received in step S407 is a channel change instruction. If it is a channel change instruction, the process proceeds to step S410. If it is not, the process returns to step S402.

(Step S410) The control unit 23 changes the channel in use in response to the received channel change instruction. Note that since this process of changing the channel in use is preferably performed simultaneously with the process of changing the channel in use in the terminal devices 4, for example, the control unit 23 may perform the process of changing the channel in use a predetermined time after the wireless communication unit 21 transmits the channel change instruction to each terminal device 4, or at a predetermined timing indicated by the channel change instruction. Then, the process returns to step S402.

(Step S411) The wireless communication unit 21 determines whether the transmission rate for each connectable wireless base station 2 and the priority of the uncommunicated application have been received from the terminal device 4, which is an uncommunicated device. If the transmission rate and the like have been received, the process proceeds to step S412; if not, the process proceeds to step S413.

(Step S412) The required resource acquisition unit 24 acquires the amount of required resources corresponding to the transmission rate received in step S411. Then, the process returns to step S402.

(Step S413) The control unit 23 determines whether to transmit information such as the amount of resources used to the management server 1. If the information is to be transmitted, the process proceeds to step S414. If not, the process returns to step S402. Note that the control unit 23 may determine to transmit the amount of required resources to the management server 1 when, for example, it has received a transmission rate or information indicating that there are no uncommunicated applications from all terminal devices 4, or may determine to transmit the amount of required resources to the management server 1 a predetermined time after transmitting the transmission request in step S408. Furthermore, after transmitting information to the management server 1 in response to a transmission request, the control unit 23 may not need to determine to transmit information to the management server 1 in step S413 until a new transmission request is received.

(Step S414) The utilization resource acquisition unit 25 acquires the utilization resource amount of each channel. Note that if the transmission rate, etc. has not been received in step S411, there is no uncommunicated device in the cell of the wireless base station 2, and therefore the channel used by the wireless base station 2 will not be changed. Therefore, in this case, the utilization resource acquisition unit 25 may acquire the utilization resource amount of only the channel in use.

(Step S415) The addable resource acquisition unit 26 acquires the amount of addable resources for each channel. Note that if the transmission rate or the like has not been received in step S411, there is no uncommunicating device in the cell of the wireless base station 2, and therefore the channel used by the wireless base station 2 will not be changed. Therefore, in this case, the addable resource acquisition unit 26 may acquire the amount of addable resources for only the channel in use.

(Step S416) The communication unit 22 transmits to the management server 1, for each uncommunicated device, the required resource amount according to each connectable wireless base station 2, the priority of the uncommunicated application, and the uncommunicated device identifier of the uncommunicated device, as well as the used resource amount and addable resource amount of each channel and the used channel acquired in steps S414 and S415. Then, the process returns to step S402.

Note that in the flowchart of FIG. 7, normal processing by the wireless base station 2, i.e., the processing of transmitting data received by the communication unit 22 from the wireless communication unit 21 and transmitting data received by the wireless communication unit 21 from the communication unit 22, is omitted. Also, the order of processing in the flowchart of FIG. 7 is one example, and the order of each step may be changed as long as similar results are obtained. For example, after a transmission request for the required resource amount, etc. is transmitted to each terminal device 4, the amount of used resources and the amount of addable resources for each channel may be obtained. Also, in the flowchart of FIG. 7, processing ends when the power is turned off or an interrupt is issued to end processing.

Next, the operation of the monitor device 3 will be described with reference to the flowchart of FIG.
(Step S501) The acquisition unit 34 determines whether or not a transmission request for a representative value has been received. If a transmission request for a representative value has been received, the process proceeds to step S502. If not, the process proceeds to step S505.

(Step S502) The acquisition unit 34 acquires a representative value of the received power that is less than the carrier sense threshold, using a histogram of the received power stored in the storage unit 33. Note that, if multiple histograms are stored in the storage unit 33, the representative value may be acquired using the latest histogram.

(Step S503) The transmission unit 35 transmits the representative value acquired by the acquisition unit 34. The destination of the representative value may be, for example, predetermined, or may be the source of the request to transmit the representative value.

(Step S504) The acquisition unit 34 resets the histogram of received power stored in the storage unit 33. This reset may involve deleting the histogram of received power that has been stored up to that point. Then, the process returns to step S501.

(Step S505) The creation unit 32 determines whether it is within the measurement period of the received power. If it is within the measurement period, the process proceeds to step S506, and if it is not, the process returns to step S501. Note that the measurement period may be continuous, for example, or it may not be continuous. In the former case, the histogram will continue to be created at time intervals according to the measurement period, and in the latter case, for example, a measurement period may be set only once between the reception of one transmission request and the reception of the next transmission request.

(Step S506) The receiver 31 receives radio waves and acquires the received power. The creator 32 then creates a histogram using the received power. Note that the creation of the histogram in step S506 may be a process of incrementing the number (frequency) of the power bin that includes the acquired received power by 1, i.e., a process of updating the histogram. Then, the process returns to step S501.

In the flowchart of FIG. 8, for example, if a transmission request is received during the measurement period, the histogram that was created partway during that measurement period may be discarded. Also, the flowchart of FIG. 8 shows a case where a representative value is acquired in response to reception of a transmission request, but this does not have to be the case. The representative value may be acquired after acquisition of the received power during the measurement period and creation of the histogram are completed. Also, the flowchart of FIG. 8 shows a case where a representative value is transmitted in response to reception of a transmission request, but this does not have to be the case. The monitor device 3 may transmit the representative value at a predetermined time interval. Also, in the flowchart of FIG. 8, the processing ends when the power is turned off or an interrupt is generated to end the processing.

Next, the operation of the terminal device 4 will be described with reference to the flowchart of FIG.
(Step S601) The wireless communication unit 41 determines whether or not a transmission request for a required resource amount, etc. has been received. If a transmission request has been received, the process proceeds to step S602, and if not, the process proceeds to step S606.

(Step S602) The control unit 42 determines whether or not an uncommunicated application exists among the applications being executed by the processing unit 46. If an uncommunicated application exists, the process proceeds to step S603, and if not, the process returns to step S601. Note that even if an uncommunicated application does not exist, a message may be sent to the effect that no uncommunicated application exists.

(Step S603) The calculation unit 44 calculates the SINR using the representative value of the interference power stored in the storage unit 43 and the reception strength of the wireless signal transmitted from the wireless base station 2. This SINR calculation may be performed, for example, for the channel in use. In addition, this SINR may be calculated for each connectable wireless base station 2 identified by performing a channel scan.

(Step S604) The transmission rate acquisition unit 45 acquires a transmission rate corresponding to the SINR calculated in step S603 using the transmission rate correspondence information. This transmission rate may be acquired for each channel used by a connectable wireless base station 2. The wireless base station 2 may or may not include a wireless base station 2 with which the terminal device 4 is currently performing wireless communication. In the latter case, for example, wireless communication with the wireless base station 2 in the terminal device's own cell may be performed using the acquired transmission rate.

(Step S605) The wireless communication unit 41 transmits the transmission rate for each connectable wireless base station 2 acquired in step S604 and the priority of the uncommunicated application to the wireless base station 2. The wireless communication unit 41 may also transmit information required for calculating the required resource amount using the transmission rate, such as the offered load and average packet size for each uncommunicated application, together with the transmission rate to the wireless base station 2. Then, the process returns to step S601.

(Step S606) The wireless communication unit 41 determines whether or not a connection destination change instruction has been received. If a connection destination change instruction has been received, the process proceeds to step S607. If not, the process proceeds to step S608.

(Step S607) In response to the received connection destination change instruction, the control unit 42 changes the wireless base station 2 to which the wireless communication unit 41 is connected in wireless communication. Then, the process returns to step S601.

(Step S608) The wireless communication unit 41 determines whether a channel change instruction has been received. If a channel change instruction has been received, the process proceeds to step S609. If not, the process proceeds to step S610.

(Step S609) In response to the received channel change instruction, the control unit 42 changes the channel in use over which the wireless communication unit 41 is performing wireless communication. Note that since this process of changing the channel in use is preferably performed simultaneously with the process of changing the channel in use at the wireless base station 2, for example, the control unit 42 may perform the process of changing the channel in use a predetermined time after the wireless communication unit 41 receives the channel change instruction, or at a predetermined timing indicated by the channel change instruction. Then, the process returns to step S601.

(Step S610) The wireless communication unit 41 determines whether or not channel information has been received. If channel information has been received, the process proceeds to step S611. If not, the process proceeds to step S612.

(Step S611) The control unit 42 stores the received channel information in a recording medium (not shown). Note that when a channel scan is performed thereafter, only the channels indicated by the channel information are scanned. Then, the process returns to step S601.

(Step S612) The wireless communication unit 41 determines whether a representative value of interference power less than the carrier sense threshold has been received. If so, the process proceeds to step S613; if not, the process returns to step S601.

(Step S613) The wireless communication unit 41 stores the received representative values in the memory unit 43. Note that it is preferable that the representative values are stored in the memory unit 43 so that the order of storage is known, that is, so that it is possible to know which representative value is newer. Then, the process returns to step S601.

In the flowchart of FIG. 9, processing related to normal communication by the terminal device 4, i.e., data transmission by the wireless communication unit 41 performed in response to execution of an application in the processing unit 46, and application processing in the processing unit 46 performed in response to data received by the wireless communication unit 41, are omitted. The order of processing in the flowchart of FIG. 9 is an example, and the order of each step may be changed as long as the same result is obtained. In addition, when the transmission rate with the wireless base station 2 of the own cell is also obtained, the transmission rate may be obtained regardless of whether or not there is an uncommunicated application in the application being executed by the processing unit 46. In addition, in the flowchart of FIG. 9, processing ends due to power off or an interrupt to end processing.

Next, the operation of the information communication system according to this embodiment will be described using a specific example. In this specific example, it is assumed that the configuration of the information communication system is as shown in FIG. 1. In this specific example, it is assumed that terminal device 4-2 is an uncommunicated device, and terminal devices 4-1, 4-3, and 4-4 are not uncommunicated devices.

First, in each wireless base station 2, a timer for transmitting a request to transmit a representative value is started (step S401). In addition, in the monitoring device 3, a histogram of the received power is created for each channel using the received power acquired during the measurement period (steps S505, S506). Then, in each cell, when the timer for transmitting a request to transmit a representative value in the wireless base station 2 expires, a request to transmit a representative value is transmitted from the wireless base station 2 to the monitoring device 3, and the timer is reset (steps S402 to S404). In response to receiving the transmission request, in the monitoring device 3, a representative value of interference power less than the carrier sense threshold using the latest histogram is acquired for each channel and transmitted to the wireless base station 2, and the histogram stored in the memory unit 33 is reset (steps S501 to S504). The representative value for each channel transmitted from the monitoring device 3 is received by the wireless base station 2 and transmitted to each terminal device 4 in the own cell via the wireless communication unit 21 (steps S405, S406). Then, the wireless communication unit 41 of each terminal device 4 receives the representative value for each channel and stores it in the memory unit 43 (steps S612, S613).

Next, it is assumed that the management server 1 determines that it is time to transmit a transmission request and transmits the transmission request to each wireless base station 2 (steps S101, S102). The transmission request is received by the communication unit 22 of each wireless base station 2, passed to the wireless communication unit 21 via the control unit 23, and transmitted from the wireless communication unit 21 to each terminal device 4 (steps S407, S408). As described above, it is assumed that an uncommunicated application exists in the terminal device 4-2 that received the transmission request. Then, in response to the reception of the transmission request in the wireless communication unit 41 of the terminal device 4-2, the control unit 42 instructs the transmission rate acquisition unit 45 to acquire a transmission rate (steps S601, S602). In response to the instruction, the transmission rate acquisition unit 45 passes an instruction to the calculation unit 44 to calculate the SINR. In response to the instruction, the calculation unit 44 acquires the RSSI of the beacon from the radio base station 2-2 of the other cell, and calculates the SINR of the channel in use for the radio base station 2-2 of the other cell using the RSSI and the representative value of the interference power less than the carrier sense threshold for each channel stored in the storage unit 43 (step S603). In addition, the transmission rate acquisition unit 45 acquires the MCS index of the channel in use for wireless communication with the radio base station 2-2 using the calculated SINR of the channel in use and the transmission rate correspondence information (step S604). This MCS index becomes the downlink transmission rate. In this specific example, the uplink transmission rate is set to be the same as the downlink transmission rate. Therefore, the wireless communication unit 41 transmits the MCS index indicating the transmission rate of the channel in use, the type of the uncommunicated application "voice communication", and the average packet size and offered load of the uncommunicated application to the radio base station 2-1 (step S605). In addition, the type of the uncommunicated application is information corresponding to the priority of the uncommunicated application. Also, as mentioned above, the only uncommunicated device is terminal device 4-2, so the other terminal devices 4-1, 4-3, and 4-4 do not transmit transmission rates, etc. (steps S601 and S602).

When the wireless communication unit 21 of the wireless base station 2-1 receives the MCS index and the like, it passes them to the control unit 42 (step S411). When the control unit 42 receives the MCS index and the like, it passes the MCS index and the average packet size and offered load of the uncommunicated application to the required resource acquisition unit 24. The required resource acquisition unit 24 uses the information to calculate the required resource amount (step S412). In this case, since the terminal device 4-2 can only newly connect to the wireless base station 2-2, one required resource amount required when wireless communication according to the uncommunicated application is performed between the terminal device 4-2 and the wireless base station 2-2 is calculated. After that, when a predetermined time has elapsed since the wireless base station 2-1 sent a transmission request to the terminal devices 4-1 and 4-2, the control unit 23 determines that the required resource amount and the like are to be sent to the management server 1 (step S413), and instructs the utilization resource acquisition unit 25 to acquire the utilization resource amount and instructs the addable resource acquisition unit 26 to acquire the addable resource amount. In response to the instruction, the resource utilization acquisition unit 25 acquires the current amount of resources utilized by the own cell according to carrier sense of the channel in use. In addition, for channels within ±3 channels from the channel in use, the resource utilization acquisition unit 25 sets the current amount of resources utilized by the own cell to the current amount of resources utilized by the own cell of the channel in use. In addition, for other channels, the resource utilization acquisition unit 25 sets the current amount of resources utilized by the own cell to 0, and passes the current amount of resources utilized by the own cell for each of these channels to the control unit 23 and the addable resource acquisition unit 26. (Step S414).

When the addable resource acquisition unit 26 receives the current amount of resources used by the own cell for each channel, it acquires the current amount of resources used by other cells according to the carrier sense of each channel. Then, the addable resource acquisition unit 26 calculates a relational expression using the current amount of resources used by the own cell and the current amount of resources used by other cells for each channel, and uses the relational expression and the boundary line to identify the maximum amount of wireless resources that can be accommodated in the own cell, and calculates the amount of addable resources by subtracting the current amount of resources used by the own cell from the maximum amount of wireless resources that can be accommodated (step S415). Then, the communication unit 22 transmits to the management server 1 the uncommunicated device identifier, which is the identifier of the terminal device 4-2, the type of the uncommunicated application, the amount of resources required when the uncommunicated application performs wireless communication with the wireless base station 2-2, the channel used by the wireless base station 2-1, and the amount of resources used and the amount of resources that can be added for each channel in the wireless base station 2-1 (step S416). This information is received by the receiver 11 of the management server 1, and stored in the memory 12 in association with the base station identifier of the wireless base station 2-1 that sent it (steps S103 and S104).

Furthermore, when a predetermined time has elapsed since the wireless base station 2-2 sent a transmission request to the terminal devices 4-3 and 4-4, the control unit 23 of the wireless base station 2-2 decides to send the required resource amount, etc. to the management server 1 (step S413), and instructs the used resource acquisition unit 25 to acquire the amount of used resources and instructs the addable resource acquisition unit 26 to acquire the amount of addable resources. Note that since the wireless base station 2-2 has no uncommunicated devices, the control unit 23 instructs to acquire the amount of used resources and the amount of addable resources only for the channels in use. In response to this instruction, when the amount of used resources and the amount of addable resources of the channels in use are acquired (steps S414, S415), the communication unit 22 transmits the amount of used resources and the amount of addable resources of the channels in use in the wireless base station 2-2, and the channels in use to the management server 1 (step S416). This information is received by the receiver 11 of the management server 1, and stored in the memory 12 in association with the base station identifier of the wireless base station 2-2 that sent it (steps S103 and S104).

After that, when a predetermined time has elapsed since the transmission of the transmission request, the connection destination determination unit 13 determines that the reception process is to be terminated (step S105) and performs a process of determining the connection destination (step S106). Specifically, the uncommunicated device identifiers are sorted by the priority of the uncommunicated application (step S201). In this specific example, since there is only one uncommunicated application, the result will not change even if this sorting is performed. On the other hand, when two or more uncommunicated device identifiers are received, the uncommunicated device identifiers may be sorted, for example, so that the type of uncommunicated application is voice communication → video communication → other communication. The order of uncommunicated device identifiers with the same type of uncommunicated application may be determined, for example, randomly or may be sorted using other information. After that, the connection destination determination unit 13 determines whether there is a wireless base station 2 that is a new connection destination (steps S202, S203). That is, the connection destination determination unit 13 acquires the required resource amount and the addable resource amount corresponding to the wireless base station 2-2, which is a wireless base station to which the terminal device 4-2 can connect, and determines whether the addable resource amount is equal to or greater than the required resource amount. For example, if the addable resource amount is equal to or greater than the required resource amount, the connection destination determination unit 13 determines that a new connection destination exists for the terminal device 4-2, which is an uncommunicating device, and determines the wireless base station 2-2 as the new connection destination (step S204). Then, the connection destination change instruction transmission unit 14 transmits a connection destination change instruction including the base station identifier of the wireless base station 2-2 to the terminal device 4-2 (step S205).

The connection change instruction is transmitted to the terminal device 4-2 via the wireless base station 2-1 and received by the wireless communication unit 41 (step S606). In response to receiving the connection change instruction, the control unit 42 controls the wireless communication unit 41 to connect to the wireless base station 2-2 identified by the base station identifier included in the connection change instruction (step S607). As a result, the terminal device 4-2 begins to perform wireless communication with the wireless base station 2-2, and the uncommunicated application becomes able to perform voice communication, eliminating the uncommunicated state. Note that this wireless communication may be performed at the transmission rate acquired by the terminal device 4-2.

On the other hand, for example, if the connection destination determination unit 13 determines that the amount of addable resources is not equal to or greater than the required amount of resources in the determination process, the terminal device 4-2, which is an uncommunicated device, cannot connect to a new connection destination. Therefore, in this case, the channel determination unit 15 determines that there is an uncommunicated device for which a new connection destination has not been determined (step S107), and performs a process of determining a new channel to be used for the wireless base station 2-1 that performs wireless communication with the terminal device 4-2, which is an uncommunicated device (step S108). Specifically, the channel determination unit 15 sorts the base station identifiers of the wireless base stations 2 that are the subject of channel determination by the number of uncommunicated devices that are performing wireless communication with the wireless base station 2 (step S301). For example, the channel determination unit 15 may determine, as an uncommunicated device at that time, an uncommunicated device for which a new connection destination has not been determined among the uncommunicated devices identified by the uncommunicated device identifiers received from the wireless base station 2. In this specific example, since there is only one wireless base station 2 that is the subject of channel determination, the result will not change even if this sorting is performed. Then, the channel determination unit 15 reads out from the storage unit 12 the amount of resources used and the amount of resources that can be added for each channel associated with the base station identifier of the wireless base station 2-1 to be the channel determination target, and the channel used by the wireless base station 2-1, and calculates a value (A+B) by adding the amount of resources used (A) and the amount of resources that can be added (B) for each channel. Then, it determines whether there is a channel whose value of A+B is greater than the value of A+B for the currently used channel (steps S302 and S303). For example, if the value of A+B for 9CH is greater than the value of A+B for the currently used channel, 6CH, the channel determination unit 15 determines the new channel to be used to be 9CH (step S304). Then, depending on the result of the determination, the channel change instruction transmission unit 16 transmits a channel change instruction to change the used channel to 9CH to the wireless base station 2-1 to be determined as the new channel to be used (step S305).

The channel change instruction sent from the management server 1 is sent to the terminal devices 4-1 and 4-2 via the wireless base station 2-1. Then, in response to the channel change instruction, the wireless base station 2-1 changes the channel used to 9CH, and the terminal devices 4-1 and 4-2 also change the channel used to 9CH (steps S409, S410, S608, S609). As a result, the channel change can resolve the non-communication state in the terminal device 4-2. After that, the channel information transmission unit 17 of the management server 1 reads out 9CH, which is the channel used by the wireless base station 2-1, and the channel used by the wireless base station 2-2 from the storage unit 12 and transmits it to each wireless base station 2 (step S109). The channel information is received by each terminal device 4-1 to 4-4 via the wireless base station 2 and stored in a recording medium (not shown) (steps S610, S611). Then, when a channel scan is performed by each terminal device 4, only the channels included in the channel information are scanned.

As described above, according to the information communication system of this embodiment, a transmission rate that takes into account interference power below the carrier sense threshold can be obtained in each terminal device 4 by using a representative value of interference power below the carrier sense threshold obtained by the monitor device 3. Therefore, the transmission rate obtained by the terminal device 4 becomes a more appropriate value, and by using this transmission rate, the number of applications that can be accommodated can be estimated with higher accuracy. As a result, the possibility of satisfying the required QoE can be increased.

In addition, by using the received power at which the cumulative probability of the probability density function obtained from the histogram of the received power is a predetermined value as a representative value of the interference power below the carrier sense threshold, the possibility of unexpected quality degradation occurring can be reduced, making it possible to obtain a more accurate transmission rate.

In this embodiment, the case where the transmission rate is acquired to acquire the required resource amount has been mainly described, but this is not necessary. The transmission rate may be acquired to determine the transmission rate used in wireless communication. The wireless communication unit 41 of the terminal device 4 may perform wireless communication with the wireless base station 2 at the transmission rate acquired by the transmission rate acquisition unit 45. In this case, wireless communication with a certain wireless base station 2 is performed using a transmission rate corresponding to the SINR calculated using the reception strength of a wireless signal transmitted from the wireless base station 2. In this way, by performing wireless communication at the transmission rate acquired by the transmission rate acquisition unit 45, the error rate can be reduced and wireless communication according to the required QoE can be realized. In this case, the transmission rate acquisition unit 45 may acquire the transmission rate only for the channel used by the own cell, for example. In this case, the information communication system may not have the management server 1, and the wireless base station 2 and the terminal device 4 may not perform processing such as changing the connection destination of the terminal device 4 in the network based on the required resource amount or changing the channel used by the wireless base station 2 in the network. By performing wireless communication using the transmission rate obtained in this way, it becomes possible to realize wireless communication with an error rate lower than a predetermined value.

In addition, in the above embodiments, each process or function may be realized by centralized processing in a single device or a single system, or may be realized by distributed processing in multiple devices or multiple systems.

In addition, in the above embodiment, the transfer of information between components may be performed, for example, by one component outputting information and the other component receiving information if the two components transferring the information are physically different, or, if the two components transferring the information are physically the same, by shifting from a processing phase corresponding to one component to a processing phase corresponding to the other component.

In addition, in the above embodiment, information related to the processing performed by each component, such as information accepted, acquired, selected, generated, transmitted, or received by each component, and information such as thresholds, formulas, and addresses used by each component in processing, may be temporarily or long-term stored in a recording medium (not shown) even if not specified in the above description. Furthermore, each component or a storage unit (not shown) may store information in the recording medium (not shown). Furthermore, each component or a reading unit (not shown) may read information from the recording medium (not shown).

In the above embodiment, if the information used by each component, such as the thresholds, addresses, and various setting values used by each component in processing, may be changed by the user, the user may or may not be able to change the information as appropriate, even if not specified in the above description. If the information is changeable by the user, the change may be realized, for example, by a reception unit (not shown) that receives a change instruction from the user, and a change unit (not shown) that changes the information in response to the change instruction. The reception unit (not shown) may receive the change instruction from an input device, may receive information transmitted via a communication line, or may receive information read from a specified recording medium.

In addition, in the above embodiment, when two or more components included in the management server 1, the wireless base station 2, the monitor device 3, or the terminal device 4 have a communication device, an input device, etc., the two or more components may have a single physical device or may have separate devices.

In the above embodiment, each component may be configured by dedicated hardware, or a component that can be realized by software may be realized by executing a program. For example, each component may be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. During execution, the program execution unit may execute the program while accessing the storage unit or recording medium. The software that realizes the monitor device 3 in the above embodiment is a program as follows. In other words, this program is a program that causes a computer to function as a creation unit that creates a histogram of the received power for each predetermined power width using the received power acquired at a predetermined sampling interval during a measurement period by a receiving unit that receives radio waves and acquires the received power of the received radio waves, an acquisition unit that acquires a representative value of the interference power less than the carrier sense threshold using the histogram of the received power created by the creation unit, and a transmission unit that transmits the representative value acquired by the acquisition unit.

The software for realizing the terminal device 4 in the above embodiment is the following program. In other words, this program causes a computer to function as a terminal device that performs wireless communication with a wireless base station, and functions as a calculation unit that calculates a signal-to-interference-plus-noise ratio using a representative value of interference power less than the carrier sense threshold received by the wireless communication unit and the reception strength of a wireless signal transmitted from the wireless base station, and a transmission rate acquisition unit that acquires a transmission rate corresponding to the signal-to-interference-plus-noise ratio calculated by the calculation unit using transmission rate correspondence information that associates the signal-to-interference-plus-noise ratio with the transmission rate.

In addition, in the above program, the functions realized by the above program do not include functions that can only be realized by hardware. For example, functions that can only be realized by hardware such as a modem or interface card in the acquisition unit that acquires information, the output unit that outputs information, and the transmission unit that transmits information are at least not included in the functions realized by the above program.

This program may also be executed by being downloaded from a server or the like, or by being read from a predetermined recording medium (for example, an optical disk such as a CD-ROM, a magnetic disk, or a semiconductor memory). This program may also be used as a program constituting a program product.

The program may be executed by a single computer or multiple computers. In other words, it may perform centralized processing or distributed processing.

Figure 13 is a schematic diagram showing an example of the appearance of a computer that executes the above program to realize the monitor device 3 and terminal device 4 according to the above embodiment. The above embodiment can be realized by computer hardware and a computer program executed thereon.

In FIG. 13, the computer system 900 includes a computer 901 including a CD-ROM drive 905, a keyboard 902, a mouse 903, and a monitor 904.

Figure 14 is a diagram showing the internal configuration of a computer system 900. In Figure 14, the computer 901 includes, in addition to a CD-ROM drive 905, an MPU (Micro Processing Unit) 911, a ROM 912 for storing programs such as a boot-up program, a RAM 913 connected to the MPU 911 for temporarily storing application program instructions and providing temporary storage space, a hard disk 914 for storing application programs, system programs, and data, and a bus 915 for interconnecting the MPU 911, the ROM 912, etc. Note that the computer 901 may also include a network card (not shown) for providing a connection to a LAN, WAN, etc.

A program that causes the computer system 900 to execute the functions of the management server 1 and the terminal device 4 according to the above embodiment may be stored in a CD-ROM 921, inserted into the CD-ROM drive 905, and transferred to the hard disk 914. Alternatively, the program may be sent to the computer 901 via a network (not shown) and stored on the hard disk 914. The program is loaded into the RAM 913 when executed. The program may be loaded directly from the CD-ROM 921 or the network. The program may also be read into the computer system 900 via another recording medium (e.g., a DVD, etc.) instead of the CD-ROM 921.

The program does not necessarily have to include an operating system (OS) or a third-party program that causes the computer 901 to execute the functions of the management server 1 or the terminal device 4 according to the above-described embodiment. The program may include only an instruction portion that calls appropriate functions or modules in a controlled manner to obtain the desired results. How the computer system 900 operates is well known, and a detailed description will be omitted.

Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included within the scope of the present invention.

As described above, a terminal device or the like according to one aspect of the present invention has the effect of being able to acquire a transmission rate that satisfies the required QoE, and is useful, for example, as a terminal device or the like that acquires a transmission rate in order to grasp the required amount of resources.

2 Radio base station 3 Monitor device 4 Terminal device 31 Receiving unit 32 Creating unit 33, 43 Storage unit 34 Acquiring unit 35 Transmitting unit 41 Wireless communication unit 42 Control unit 44 Calculating unit 45 Transmission rate acquiring unit 46 Processing unit

Claims (10)

A terminal device that performs wireless communication with a wireless base station,
a wireless communication unit that receives a representative value of interference power that is less than a carrier sense threshold;
a calculation unit that calculates a signal-to-interference-and-noise ratio using the representative value of the interference power and a reception strength of a radio signal transmitted from a radio base station;
A terminal device comprising: a transmission rate acquisition unit that acquires a transmission rate corresponding to the signal-to-interference-plus-noise ratio calculated by the calculation unit, using transmission rate correspondence information that associates the signal-to-interference-plus-noise ratio with a transmission rate. the transmission rate acquisition unit acquires a transmission rate for each connectable wireless base station when an uncommunicated application that is an application that cannot perform wireless communication exists;
the wireless communication unit transmits to the wireless base station, information that enables the wireless base station that wirelessly communicates with the terminal device to transmit to a management server a required resource amount, which is a wireless resource necessary for wireless communication of the uncommunicated application for each wireless base station to which the terminal device can be connected, calculated according to the transmission rate, and a priority of the uncommunicated application, and when a wireless base station to which the terminal device is to be newly connected is determined in the management server in response to the transmission, receives from the management server a connection destination change instruction to change the connection destination in accordance with the determination result by the management server;
2. The terminal device according to claim 1, further comprising a control unit that, when the wireless communication unit receives the connection destination change instruction, controls the wireless communication unit to change the wireless base station to which the wireless communication unit is connected in response to the connection destination change instruction. The terminal device according to claim 1, wherein the wireless communication unit performs wireless communication with a wireless base station at the transmission rate acquired by the transmission rate acquisition unit. A receiving unit that receives radio waves and acquires the reception power of the received radio waves;
a generation unit that generates a histogram of the received power for each predetermined power width using the received power acquired by the receiving unit at a predetermined sampling interval during a measurement period;
an acquisition unit that acquires a representative value of interference power less than a carrier sense threshold using the histogram of received power created by the creation unit;
A monitoring device comprising: a transmitter that transmits the representative value acquired by the acquisition unit. The monitor device according to claim 4, wherein the representative value is a received power at which the cumulative probability of a probability density function obtained from a histogram of received power in a range above the noise floor and below the carrier sense threshold is a predetermined value. A monitor device according to claim 4 or 5,
4. An information communication system comprising: the terminal device according to claim 1, which acquires a transmission rate by using the representative value transmitted from the monitor device. A transmission rate acquisition method that is processed in a terminal device that performs wireless communication with a wireless base station, comprising:
receiving a representative value of interference power below a carrier sense threshold;
calculating a signal-to-interference-and-noise ratio using the representative value of the interference power and a reception strength of a radio signal transmitted from a radio base station;
acquiring a transmission rate corresponding to the calculated signal-to-interference-plus-noise ratio by using transmission rate correspondence information that associates the signal-to-interference-plus-noise ratio with the transmission rate. receiving radio waves and acquiring reception power of the received radio waves;
creating a histogram of received power for each predetermined power range using received power acquired at a predetermined sampling interval during a measurement period;
obtaining a representative value of interference power less than a carrier sense threshold using the created histogram of received power;
and transmitting the acquired representative value. Computer,
Functioning as a terminal device that performs wireless communication with a wireless base station;
a calculation unit that calculates a signal-to-interference-and-noise ratio using a representative value of interference power less than a carrier sense threshold received by the wireless communication unit and a reception strength of a wireless signal transmitted from a wireless base station;
A program for causing the program to function as a transmission rate acquisition unit that acquires a transmission rate corresponding to the signal-to-interference-plus-noise ratio calculated by the calculation unit, using transmission rate correspondence information that associates the signal-to-interference-plus-noise ratio with a transmission rate. Computer,
a creation unit that creates a histogram of the received power for each predetermined power range using the received power acquired at a predetermined sampling interval during a measurement period by a receiving unit that receives radio waves and acquires the received power of the received radio waves;
an acquisition unit that acquires a representative value of interference power less than a carrier sense threshold using the histogram of received power created by the creation unit;
A program for causing the device to function as a transmission unit that transmits the representative value acquired by the acquisition unit.

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