JP6539891B2 - Base station system, communication terminal, wireless communication system, control method of base station system, control method of communication terminal, and program - Google Patents

Description

  The present invention relates to a base station system, a communication terminal, a wireless communication system, a control method of a base station system, a control method of a communication terminal, and a program.

  Conventionally, a wireless communication terminal (hereinafter also referred to as a communication terminal) and a wireless base station apparatus (hereinafter referred to as a base station) for communicating with the communication terminal via a wireless communication link (hereinafter also referred to as a communication link) are used. Wireless local area network (WLAN) is used. The communication terminal can communicate with another communication device (such as a web server or a mail server) on the network connected to the WLAN via the WLAN.

  In wireless communication, in general, the success rate of communication is improved by avoiding collision of communication frames. However, if there is an extraneous wave of the same frequency band as the frequency band (hereinafter also referred to as a channel) of the radio wave used for the wireless communication, the radio wave of the wireless communication is disturbed and the communication fails. Also, when the amount of communication is large, the possibility of communication frame collisions increases, and the throughput decreases due to the increase in latency for collision avoidance. Therefore, in order to keep the throughput of wireless communication high, it is desirable to select a channel with as few extraneous waves as possible and with few communication by other communication terminals.

  Patent Document 1 discloses a communication method between a base station equipped with two wireless interfaces and a communication terminal. According to this technique, communication data is transmitted and received by one of the two wireless interfaces, and the other transmits a decryption key of the communication data. Thus, encrypted communication can be performed while suppressing a decrease in the amount of communication.

JP, 2012-060443, A

  However, when the channel used by the base station is switched to a channel capable of high quality wireless communication, communication with a terminal communicating on the channel is temporarily disconnected. If the communication is disconnected, there is a problem that the control or service to be realized by the communication can not be properly realized. This problem becomes more pronounced when communication breaks out over a long period of time.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a base station system or the like which reduces communication loss at the time of switching a wireless communication channel.

  In order to solve the above problems, a base station system according to an aspect of the present invention is capable of wireless communication on a first interface capable of wireless communication on a first channel and on a second channel different from the first channel. A second interface, a queue for storing a frame for a communication terminal output by the second interface, and the communication terminal connected to the first interface are connected from the first interface to the second interface And a queue control unit configured to transmit a frame stored in the queue from the second interface to the communication terminal when connection switching is performed to the interface.

  According to this, the base station system stores, in the queue, the frame to be delivered to the communication terminal during the time the communication terminal switches from communication with the first interface to communication with the second interface. After that, when the communication terminal starts communication with the second interface, the frame stored in the queue is transmitted to the communication terminal. Therefore, the loss of the frame to be delivered to the communication terminal can be reduced. Furthermore, by switching the communication terminal from the first interface to the communication with the second interface, it is possible to make frame loss zero if all frames to be delivered from the base station system to the communication terminal are stored in the queue. is there. Thus, the base station system reduces communication loss when switching wireless communication channels.

  Further, the queue control unit may transmit the frame stored in the queue in response to reception of a notification frame to be transmitted after the communication terminal is connected to the second interface.

  According to this, the base station system detects that the communication terminal has connected to the second interface by receiving the notification frame, and transmits the frame stored in the queue to the communication terminal. Thus, the base station system more easily reduces communication loss when switching wireless communication channels.

  In addition, the second interface holds the same setting information as the first interface, and the base station system further transmits the second interface before the communication terminal connects to the second interface. A control unit may be provided to register the communication terminal in a terminal list.

  According to this, the base station system registers the communication terminal in the terminal list of the second interface before the communication terminal actually starts communication with the second interface. By this, when the communication terminal actually starts communication with the second interface, it is possible to transmit the frame only by receiving the notification packet from the communication terminal, so the communication terminal actually receives the second interface. The process after communication starts can be simplified.

  Further, when registering the communication terminal in the terminal list, the control unit registers information indicating that the communication terminal is in a power save state conforming to the IEEE 802.11 standard, and the queue is IEEE 802. It may be a power save queue conforming to the 11 standards.

  According to this, the base station system can reduce the communication loss at the time of switching of the wireless communication channel more specifically by using the mechanism of the power save state and the power save queue compliant with the IEEE 802.11 standard.

  Further, the notification frame may be a NULL frame whose power save bit according to the IEEE 802.11 standard is 0.

  According to this, the base station system uses the mechanism of the power save state and the power save queue compliant with the IEEE 802.11 standard, and suppresses the data amount of the notification frame to reduce the communication loss when switching the wireless communication channel. Can be reduced.

  The base station system may include one base station, and the one base station may include the first interface and the second interface.

  According to this, the base station system can reduce the communication loss at the time of switching of the wireless communication channel by using one base station provided with two wireless interfaces.

  The base station system may include a first base station and a second base station, the first base station may include the first interface, and the second base station may include the second interface.

  According to this, two base stations provided with one radio interface can be used to reduce the communication loss at the time of switching of the radio communication channel.

  Further, the base station system further performs wireless communication with the communication terminal on the first channel using the first interface, and obtains a communication status of the first channel, and the wireless communication. The radio wave condition around the second interface is acquired using the second interface during radio communication by the communication unit, and the radio wave condition acquired by the radio communication unit is acquired by the radio communication unit storing the acquired radio wave condition in the storage unit; A determination unit that determines a preferred channel estimated to be capable of wireless communication of higher quality than wireless communication using the first channel, based on the communication status and the radio wave status stored in the storage unit; And the second interface performs wireless communication with the communication terminal on the preferred channel, and the queue control unit performs the second channel on the preferred channel. Used as le, if the communication terminal is connected to the second interface, it may send a frame that is stored in the queue.

  According to this, while performing wireless communication with the communication terminal by one wireless interface, the base station system acquires surrounding radio wave conditions using another wireless interface not used for the wireless communication. Then, when a suitable channel is determined based on the acquired radio wave condition, the base station system can perform channel switching so as to perform wireless communication with the communication terminal on the suitable channel. Communication loss can be reduced.

  The communication terminal according to an aspect of the present invention is a terminal interface capable of wireless communication, and the terminal interface is different from the first channel in connection with the first channel of the wireless interface of the base station system. And a notification unit that transmits a notification frame by the terminal interface upon switching to connection to the wireless interface of the base station system on two channels.

  According to this, by transmitting the notification frame, the terminal can receive the frame accumulated in the queue of the wireless interface during the switching of the channel from the wireless interface connected by the switching of the wireless communication channel. Thus, the terminal can reduce communication loss at the time of switching the wireless communication channel.

  A wireless communication system according to an aspect of the present invention includes the above-described base station system and a communication terminal connected to the base station system.

  According to this, the same effect as the above-mentioned base station system is produced.

  Further, a control method of a base station system according to an aspect of the present invention is a control method of a base station system, wherein the base station system is a first interface capable of wireless communication on a first channel; A second interface capable of wireless communication in a second channel different from one channel, and a queue provided in the second interface, wherein the control method is a frame for a communication terminal output by the second interface Storing the frame stored in the queue when the communication terminal connected to the first interface switches connection from the connection with the first interface to the second interface; Transmitting from the two interfaces to the communication terminal.

  According to this, the same effect as the above-mentioned base station system is produced.

  A control method of a communication terminal according to an aspect of the present invention is a control method of a communication terminal provided with a terminal interface capable of wireless communication, wherein the terminal interface is a first channel with a wireless interface of a base station system. Establishing a connection in the second channel, and connecting the terminal interface with the wireless interface of the base station system from a first channel connection with the wireless interface of the base station system to a second channel different from the first channel. And sending a notification frame by the terminal interface upon switching to the terminal.

  According to this, the same effect as the above-mentioned communication terminal is produced.

  Further, a program according to an aspect of the present embodiment is a program for causing a computer to realize the control method of the above-mentioned base station system.

  According to this, the same effect as the above-mentioned base station system is produced.

  Moreover, a program according to an aspect of the present embodiment is a program for causing a computer to realize the control method of the communication terminal.

  According to this, the same effect as the above-mentioned communication terminal is produced.

  The present invention can be realized not only as an apparatus, but also as a method in which processing means constituting the apparatus are steps, or a program which causes the computer to execute the steps, or a computer reading the program It can be realized as a recording medium such as a possible CD-ROM, or as information, data or signals indicating the program. And these programs, information, data, and signals may be distributed via a communication network such as the Internet.

  The base station system according to the present invention can reduce communication loss when switching wireless communication channels.

FIG. 1 is a block diagram of a radio communication system including a base station according to the embodiment. FIG. 2 is a block diagram showing a hardware configuration of a base station according to the embodiment. FIG. 3 is a block diagram showing a functional configuration of a base station according to the embodiment. FIG. 4 is an explanatory diagram of a band occupancy rate which is an example of the radio wave condition acquired by the condition acquisition unit according to the embodiment. FIG. 5 is an explanatory diagram of a frame capture log which is an example of the radio wave status acquired by the status acquisition unit according to the embodiment. FIG. 6 is an explanatory diagram of an example of the analysis result of the frame capture log according to the embodiment. FIG. 7 is a flow chart showing processing of a base station according to the embodiment. FIG. 8 is a sequence diagram showing a method of connection switching in the wireless communication system according to the embodiment. FIG. 9 is a block diagram focusing on the channel switching function of the base station and terminal according to the embodiment. FIG. 10 is an explanatory diagram of a terminal list of a wireless interface of a base station according to the embodiment. FIG. 11 is a flowchart focusing on the channel switching function of the base station according to the embodiment. FIG. 12 is a flowchart focusing on the channel switching function of the terminal according to the embodiment. FIG. 13 is a block diagram focusing on a channel switching function of a base station system and a terminal according to a modification of the embodiment.

  Embodiments will be specifically described below with reference to the drawings.

  Each of the embodiments described below shows a preferable specific example of the present invention. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and the present invention is not limited thereto. Further, among the components in the following embodiments, components not described in the independent claim indicating the highest concept of the present invention will be described as optional components constituting a more preferable embodiment.

  In addition, the same code | symbol may be attached | subjected to the same component and description may be abbreviate | omitted.

Embodiment
A base station system etc. which reduce the communication loss at the time of switching of a radio | wireless communication channel in this Embodiment are demonstrated. First, a technology related to a radio base station apparatus and a radio communication system capable of dynamically determining a channel capable of wireless communication with higher quality will be described, and then a technology for reducing communication loss when switching to the determined channel Will be explained.

<Technology to determine higher quality channel>
FIG. 1 is a block diagram of a radio communication system 1 including a base station 10 according to the present embodiment.

  As shown in FIG. 1, the wireless communication system 1 includes a base station 10 and a communication terminal 20. The wireless communication system 1 is connected to a LAN 30 (Local Area Network) and a network 40.

  The base station 10 is a wireless base station device that performs wireless communication with the communication terminal 20. The base station 10 has a wireless interface, establishes a communication link with the communication terminal 20 present in the wireless communicable area, and performs wireless communication. Further, the base station 10 is connected to the LAN 30, and transfers the communication frame to the destination according to the destination of the communication frame (communication packet) used for wireless communication. Note that wireless communication is realized by, for example, a wireless LAN conforming to the IEEE 802.11a, b, g, n standards and the like. The base station 10 is an example of a base station system.

  The base station 10 includes two wireless interfaces W1 and W2, and appropriately uses them to find a channel capable of wireless communication with higher quality, and perform wireless communication with the communication terminal 20 using the found channel. . How to use the two wireless interfaces W1 and W2 will be described in detail later.

  The communication terminal 20 is a wireless communication terminal having a wireless interface. The communication terminal 20 establishes a communication link with either of the wireless interfaces W1 or W2 that the base station 10 has, and performs wireless communication. The communication terminal 20 can communicate with the LAN 30 or another communication device (not shown) connected to the network 40 via the base station 10.

  The LAN 30 is a communication network (local area network) connected to the base station 10 and the network 40. The LAN 30 is realized by, for example, a wired LAN conforming to the IEEE 802.3 standard or the like.

  The network 40 is an external communication network connected to the LAN 30. The network corresponds to, for example, an access network in a telecommunications carrier, the Internet, or the like.

  The hardware configuration and functional configuration of the base station 10 in the wireless communication system 1 configured as described above will be described.

  FIG. 2 is a block diagram showing a hardware configuration of base station 10 according to the present embodiment.

  As illustrated in FIG. 2, the base station 10 includes a central processing unit (CPU) 101, a read only memory (ROM) 102, a main memory 103, a storage 104, and wireless interfaces W1 and W2.

  The CPU 101 is a processor that executes a control program stored in the ROM 102 or the storage 104 or the like.

  The ROM 102 is a read only storage area that holds control programs and the like.

  The main memory 103 is a volatile storage area used as a work area used when the CPU 101 executes a control program.

  The storage 104 is a non-volatile storage area that holds a control program, content, and the like.

  The wireless interface W1 is a wireless communication interface that establishes a communication link with the communication terminal 20 and performs wireless communication. The wireless interface W1 is, for example, a wireless LAN communication interface conforming to the IEEE 802.11a, b, g, n standards, etc., and includes a wireless communication signal generation circuit, an antenna, and the like. The wireless interface W1 is used as a communication interface for wireless communication or a monitoring interface for acquiring the radio wave condition around the base station 10, as described later. A predetermined Service Set Identifier (SSID) and a Basic Service Set Identifier (BSSID) are set in the wireless interface W1. Information such as SSID and BSSID set in the wireless interface is also referred to as setting information.

  The wireless interface W2 is a wireless communication interface having the same hardware configuration as the wireless interface W1, and is used in the same application as the wireless interface W1. The wireless interface W2 operates independently of the wireless interface W1. The same setting information (that is, SSID and BSSID) as the wireless interface W1 is set in the wireless interface W2.

  The antenna of the wireless interface W1 and the antenna of the wireless interface W2 are provided in the housing of one base station 10, and are disposed at an interval of, for example, about 10 cm.

  FIG. 3 is a block diagram showing a functional configuration of base station 10 according to the present embodiment.

  As shown in FIG. 3, the base station 10 includes a wireless communication unit 111, a communication interface 112, a status acquisition unit 113, a monitoring interface 114, a storage unit 115, a determination unit 116, and a control unit 117. And

  The wireless communication unit 111 is a processing unit that performs wireless communication with the communication terminal 20. Specifically, the wireless communication unit 111 establishes a communication link with the communication terminal 20 by the communication interface 112, and transmits and receives communication frames with the communication terminal 20 through the established communication link. The communication interface 112 dynamically uses one or both of the wireless interfaces W1 and W2. The determination unit 116 determines which of the wireless interfaces W1 and W2 the wireless communication unit 111 uses as the communication interface 112 at which timing. The wireless communication unit 111 is realized by the CPU 101, the ROM 102, the main memory 103, and the like (hereinafter, also referred to as the CPU 101 and the like).

  The wireless communication unit 111 also provides the determination unit 116 with the communication status of the channel (hereinafter also referred to as “communication channel”) that the communication interface 112 uses for wireless communication. The communication status is information including the band occupancy rate of wireless communication in the communication channel, the number of frames transmitted and received (at least one of transmission and reception) by the communication interface 112, and the like.

  Further, to change the channel used for wireless communication with the communication terminal 20, communication is performed from one of the wireless interfaces W1 and W2 used by the wireless communication unit 111 as the communication interface 112 to the other wireless interface. It is realized by the terminal 20 performing connection switching. Here, the channel of the one radio interface and the channel of the other radio interface are different from each other. As described later, if the wireless communication management information applied to both wireless interfaces is the same except for the channel, the communication terminal recognizes that only the channel is to be changed.

  At this time, if the other wireless interface is set to a channel capable of wireless communication with higher quality before connection switching, wireless communication can be performed on the channel by the connection switching. Become.

  Further, the change of the channel is performed by stopping the operation (for example, transmission of a radio wave) of one of the radio interfaces used by the radio communication unit 111 as the communication interface 112 so that the communication terminal 20 voluntarily performs the other radio. It may be realized by searching for an interface. Further, the change of the channel may be triggered by the radio communication unit 111 transmitting a notification signal for channel switching to the communication terminal 20 and the communication terminal 20 receiving the notification signal. The above notification signal includes, for example, CSA in an Action Frame which is a frame format including a channel switch announcement (CSA) defined by the IEEE 802.11h standard and a spectrum management action defined by the IEEE 802.11 standard (hereinafter referred to as Action Frame). (Also called CSA). In particular, it is preferable that the base station 10 announces the change target channel by unicast communication with the communication terminal 20 by Action Frame CSA. In this way, the destination channel can be reliably notified to the communication terminal 20 as compared with the CSA (CSA defined by the IEEE 802.11h standard) included and transmitted in the beacon.

  Returning to FIG. 3, the communication interface 112 is a wireless interface used by the wireless communication unit 111 to establish and maintain a communication link with the communication terminal 20. One or both of the wireless interfaces W1 and W2 are dynamically used as the communication interface 112 based on control by the control unit 117.

  The communication interface 112 also stores management information (hereinafter also referred to as wireless communication management information) necessary for wireless connection of a plurality of communication terminals connected to the base station 10. Here, the management information necessary for wireless connection is management information of each communication terminal regarding authentication and encryption, management information required between the base station 10 and the driver of each communication terminal, and the like. Based on the wireless communication management information, the base station 10 and the communication terminal 20 perform wireless communication with each other. The communication interface 112 is realized by one of the wireless interfaces W1 and W2 and a part of the storage 104 or the like.

  The status acquisition unit 113 is a processing unit that acquires radio wave conditions around the base station 10 during wireless communication by the wireless communication unit 111, and stores the acquired radio wave conditions in the storage unit 115. Specifically, the status acquisition unit 113 acquires the radio wave status a plurality of times with the passage of time in each of the channels available for wireless communication while changing the channel by the monitoring interface 114. For example, after acquiring the radio wave status for 500 msec in one of the channels available for wireless communication, the status acquisition unit 113 acquires the radio wave status in the same manner in another channel available for wireless communication. By performing this for all channels available for wireless communication, the radio wave status of each channel available for wireless communication is acquired. In addition, the condition acquisition unit 113 repeatedly acquires the above-mentioned radio wave conditions to obtain radio wave conditions in all channels available for wireless communication over a long time (for example, several hours, several days, or more). Are stored in the storage unit 115.

  The radio wave status acquired by the status acquisition unit 113 is, for example, a band occupancy rate for each channel, a frame capture log, a noise floor value of extraneous noise, or detection of communication that may hinder its own communication. Here, the communication that may inhibit its own communication is, for example, communication that bundles multiple channels such as noise causing delay and IEEE 802.11ac. Such communication is harmful when it is desired to operate the wireless communication system 1 under an application that requires the delay to be minimized. The monitoring interface 114 dynamically uses one of the wireless interfaces W1 and W2. The determination unit 116 determines which of the wireless interfaces W1 and W2 is to be used as the monitoring interface 114 by the status acquisition unit 113, and the specific timing is entirely arbitrary. For example, switching may be performed immediately when a better communication channel is found, or switching may be performed when the communication status in the current communication channel deteriorates below a certain threshold. Alternatively, it may be possible to reserve a switching time in a time zone in which communication with each terminal is interrupted, such as nighttime. This is because it is possible to suppress the influence of the interruption time of the wireless communication accompanying the channel switching. The condition acquisition unit 113 is realized by the CPU 101 or the like.

  The monitoring interface 114 is a wireless interface used by the status acquisition unit 113 to acquire the radio wave status around the base station 10. One of the wireless interfaces W1 and W2 is dynamically used as the monitoring interface 114 based on control by the control unit 117.

  The storage unit 115 is a storage device in which the radio wave condition around the base station 10 is stored as the condition history 121. The situation history 121 is history data in which the radio wave situation acquired by the situation acquisition unit 113 is stored as time series data, and is read out and used by the determination unit 116. The storage unit 115 is realized by the storage 104.

  The determination unit 116 can perform wireless communication of higher quality than the wireless communication in the communication channel based on the communication status acquired by the wireless communication unit 111 and the radio wave status (status history 121) stored in the storage unit 115. Determine the preferred channel which is the channel to be estimated. Specifically, the determination unit 116 acquires the communication status of the communication channel from the wireless communication unit 111. Further, the determination unit 116 is a radio wave condition (condition history 121) stored in the storage unit 115, a band occupancy rate for each of the channels usable by the wireless interfaces W1 and W2, or a capture log of wireless frames (hereinafter referred to as “ It is acquired by reading out from the storage unit 115). And based on the said communication condition and the said radio wave condition, the suitable channel which is a channel estimated that wireless communication of higher quality can be performed is determined. The specific determination method will be described in detail later.

  The control unit 117 is a processing unit that controls a wireless interface used by each of the wireless communication unit 111 and the status acquisition unit 113. Specifically, when the determination unit 116 determines the preferred channel, the control unit 117 controls the monitoring interface 114 to operate as a new communication interface 112 that performs wireless communication on the preferred channel. . Further, in the above case, the control unit 117 controls the wireless interface used as the communication interface 112 to newly operate as the monitoring interface 114. Furthermore, when the determination unit 116 determines the preferred channel and the channel switching time arrives, the control unit 117 determines the wireless communication management information (obtained through the communication interface 112) stored in the communication interface 112. Then, the monitoring interface 114 is copied and stored, and the function as the monitoring interface is stopped to start preparation for starting the operation as the communication interface.

  Further, when the determination unit 116 determines the start time as well as the preferred channel, the control unit 117 controls to start a new operation of the communication interface 112 at the start time.

  Next, the radio wave status acquired by the status acquisition unit 113 will be described with reference to two specific examples. The first example is the bandwidth occupancy per channel, and the second example is a capture log.

  FIG. 4 is an explanatory diagram of a band occupancy rate which is an example of the radio wave status acquired by the status acquisition unit 113 according to the present embodiment. (A), (b) and (c) of FIG. 4 are graphs showing band occupancy rates at different times respectively for each channel.

  For example, the graph shown in (a) of FIG. 4 shows the band occupancy of the channel such that the band occupancy of channel 1 is about 83% and the band occupancy of channel 2 is about 61%. From this graph, it is determined that the band occupancy of channels around channels 1 and 8 is relatively high, and the channels around channels 4 and 11 are relatively low in band occupancy.

  From the respective graphs of (b) and (c) of FIG. 4, a channel having a relatively low band occupancy or a high channel is determined from the same idea as described above.

  The determination unit 116 determines the preferred channel as follows using the band occupancy rate shown in FIG. For example, the band occupancy rates of the respective channels acquired three times with a time interval in a predetermined time are (a), (b) and (c) in FIG. 4 and the band of the communication channel of the communication interface 112 Assume that the occupancy rate is about 30%. At this time, from (a), (b) and (c) of FIG. 4, the determination unit 116 determines a channel whose band occupancy rate is continuously 30% or less within a predetermined time. As a result of the determination, the determination unit 116 selects the channel 11 as a channel whose band occupancy rate is continuously 30% or less, and determines the preferred channel as the channel 11.

  FIG. 5 is an explanatory diagram of a capture log which is an example of the radio wave status acquired by the status acquisition unit 113 according to the present embodiment.

  The capture log shown in FIG. 5 indicates information on a plurality of communication frames acquired by the monitoring interface 114, and the time 501, source address 502, destination address 503, communication for each of the plurality of communication frames. The channel 504 and the information of the frame length 505 are included.

  The time 501 is information indicating the time when the monitoring interface 114 has acquired the communication frame. The time 501 may absolutely indicate the time or may relatively indicate the time. The time 501 is, for example, based on the time of the oldest communication frame on the capture log, the time from the time of the oldest communication frame to the reference to the time of reception of the communication frame, that is, relative to the time of the reference The time is Note that the minimum unit of time when the time 501 is measured is approximately 1 microsecond to 1 millisecond.

  The transmission source address 502 is information indicating the transmission source MAC address of the communication frame. In FIG. 4, "MAC (A1) etc." means the MAC address of the base station A1 (not shown), and "MAC (S1)" etc. means the MAC address of the communication terminal S1 (not shown). Do. The MAC address is generally expressed as “11: 22: 33: aa: bb: cc” in 12-digit hexadecimal number.

  The destination address 503 is information indicating the destination MAC address of the communication frame. The contents described are the same as those for the source address 502.

  The communication channel 504 is information indicating a channel from which the communication frame is obtained.

  The frame length 505 is information indicating the frame length of the communication frame.

  The determination unit 116 determines the preferred channel as follows by analyzing the capture log shown in FIG.

  FIG. 6 is an explanatory diagram of an example of the analysis result of the capture log according to the present embodiment.

  As shown in FIG. 6, in the analysis result of the capture log, the number of terminals 601 and the number of base stations 602 performing communication in each channel, the number of communication frames 603 communicated in each channel, and the communication data amount 604 ( The unit includes, for example, [kbps]).

  A method of calculating the number of terminals 601 and the number of base stations 602 will be described below. In the following description, an address means a MAC address.

  From the source address 502 and the destination address 503 included in the capture log, it is not known whether the address is a terminal address or a base station address. Therefore, in order to know that the address is an address of a terminal or a base station, the determination unit 116 corresponds the transmission source address 502 and the destination address 503 of each communication frame as a pair in a plurality of communication frames in the capture log. It holds and determines whether the address is that of the terminal or that of the base station based on this correspondence. Specifically, the determination unit 116 determines that an address relatively frequently included in one of the pairs is the address of the base station. In this method, since the base station 10 mutually transfers communication frames exchanged between another communication device connected to the LAN 30 and the communication terminal 20, the address of the base station is included in one of the above pairs. It is a method that utilizes the fact that the frequency is naturally high.

  In the above, when determining whether the frequency is high, the determination may be made based on the result of comparing the frequency and a predetermined value. In addition, an appropriate value that can distinguish the base station from the other communication devices based on the frequency distribution may be set as the predetermined value.

  If there is a predetermined address as the address of the base station or terminal, the address may be used to determine whether the address is that of the base station or that of the terminal.

  The method of calculating the number of communication frames 603 and the amount of communication data 604 will be described below.

  The communication frame number 603 is obtained as the number of communication frames acquired from a specific channel in the capture log. The communication data amount 604 extracts communication data per unit time based on the transmission / reception time (time 501) of each frame and the frame length 505 after extracting only the frames acquired from the specific channel from the capture log. It is obtained by calculating the quantity.

  The determination unit 116 determines a channel whose number of terminals 601, number of base stations 602, number of communication frames 603, or communication data amount 604 is equal to or less than a predetermined value as a channel with a low degree of congestion. Then, the determination unit 116 determines a channel obtained as a result of the determination as a preferred channel. When determining a suitable channel, the congestion degree may be comprehensively evaluated and used from the number of terminals 601, the number of base stations 602, the number of communication frames 603, and the communication data amount 604, or these may be predetermined. Any one or more analysis results may be used. Further, in the case where there are a plurality of preferred channels determined using the band occupancy rate, it is also effective to narrow down the preferred channels in consideration of the number of terminals 601 and the like.

  The operation of the base station 10 configured as described above will be described below.

  FIG. 7 is a flowchart showing the processing of the base station 10 according to the present embodiment.

  In a state where the communication terminal 20 establishes a communication link with the wireless interface W1 as the communication interface 112, the base station 10 performs the subsequent processing, whereby the communication terminal 20 communicates with the wireless interface W2. Is established.

  In step S101, the determination unit 116 acquires the communication status of the communication channel from the wireless communication unit 111.

  In step S102, the determination unit 116 acquires, from the storage unit 115, the situation history 121 as the radio wave situation around the base station 10.

  In step S103, the determination unit 116 determines a suitable channel using the communication status acquired in step S101 and the radio wave status acquired in step S102, and determines whether to switch to the suitable channel and the timing of switching. decide.

  In step S104, when the channel switching timing arrives, prior to the switching, the control unit 117 duplicates and stores the wireless communication management information in use (stored) in the communication interface 112 in the monitoring interface 114. As described above, the timing of channel switching is arbitrary.

  In step S105, the control unit 117 controls the wireless communication unit 111 to use the wireless interface W2 used as the monitoring interface 114 as the new communication interface 112. Specifically, the wireless interface W2 is reset as a communication interface, the preferred channel determined in step S103 is set, and the wireless communication management information of the communication interface 112 stored in the monitoring interface 114 in step S104. Set

  In step S106, the wireless communication unit 111 unicasts to the communication terminal 20 Action Frame CSA including the preferred channel as a notification signal for channel switching from the communication channel to the preferred channel.

  In step S107, the communication terminal 20 performs connection switching of the communication link from the wireless interface W1 to the wireless interface W2. Connection switching is performed with the wireless interface W2 without the communication terminal 20 disconnecting the communication link with the wireless interface W1 by the information of the preferred channel by the Action Frame CSA of step S106 and the wireless communication management information stored in the wireless interface W2. This is done by establishing a communication link. That is, the wireless communication management information of the communication terminal 20 necessary for wireless connection can be referred to, and the communication link before the connection switching can be taken over just by performing the substantial channel change. Normally, connection switching requires that the communication link be disconnected once and a new communication link be established. In addition, according to the normal handover technology (the conventional handover technology which is not the fast handover technology), the time for scanning the channel for searching for the connection destination base station (about several seconds, more specifically, 1 to 3 seconds) In addition to the degree), it takes about 200 msec for authentication etc. required for the communication terminal 20 to connect the communication link with the wireless interface W2.

  After confirming in step S108 that all connected communication terminals have been switched to the new communication channel, the wireless interface W2 notifies the wireless interface W1 of the completion of switching.

  In step S109, the control unit 117 controls the status acquisition unit 113 to use the wireless interface W1 used as the communication interface 112 as the new monitoring interface 114. That is, during steps S104 to S109, the two modules coexist in different channels and operate as communication interfaces.

  Through the above series of processing, the base station 10 dynamically determines a channel capable of wireless communication with high quality, and the base station 10 and the communication terminal 20 perform wireless communication without disconnecting the communication link in the determined channel. It can be carried out.

  FIG. 8 is a sequence diagram showing a method of connection switching in the wireless communication system 1 according to the present embodiment. About the process demonstrated in FIG. 7, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  First, it is assumed that the communication terminal 20 has not established a communication link with any wireless interface, and the base station 10 uses the wireless interface W1 as the communication interface 112.

  When the communication terminal 20 establishes a communication link with the base station 10 (wireless interface W1), first, scanning of a channel by the communication terminal 20 is performed. Channel scanning generally takes a few seconds, more specifically, about 1 to 3 seconds. Further, after scanning the channel, authentication (Authentication), connection (Association) and exchange of key information (4-way handshake) are performed between the communication terminal 20 and the wireless interface W1. These exchanges generally take about 200 msec. After this exchange, wireless communication between the communication terminal 20 and the base station 10 becomes possible.

  After that, the radio interface monitors the status of each channel as a monitoring interface, and as a result, the preferred channel is determined (step 103), and communication from the control unit 117 is performed when the timing of performing processing to switch to the preferred channel (step S104) comes. An Action Frame CSA including the preferred channel is transmitted to the terminal 20 (step S106). Communication terminal 20 will change a channel, if this is received (Step S107).

  When the wireless interface W2 is started to be used as the communication interface 112, the communication terminal 20 switches the use channel to the preferred channel included in ActionFrame CSA.

  After the communication terminal 20 establishes a communication link with the wireless interface W2, the wireless interface W2 notifies the wireless interface W1 of the completion of switching. Based on this notification, the status acquisition unit 113 newly acquires the radio wave status around the base station 10 using the wireless interface W1 as the monitoring interface 114.

  When the wireless interface W1 is newly used as the monitoring interface 114, the status acquisition unit 113 stores the acquired radio wave status history in the continued status history 121. By doing this, the missing period of the history data on the situation history 121 can be shortened.

  The base station 10 has two wireless interfaces W1 and W2 mounted on one base station 10, which has the following advantages.

  First, at the time of channel switching, there is an advantage that the change in the physical position of the antenna of the wireless interface is small, and the change in communication characteristics accompanying the channel switching can be kept small. In a normal use state, it is considered that the base station 10 and the communication terminal 20 are often arranged at a distance of several meters apart. In the case where the distance between the antennas of the wireless interfaces W1 and W2 is 10 cm, from the viewpoint of the communication terminal 20, it appears that the antenna moves about 10 cm by channel switching. However, compared to the distance between the base station 10 and the communication terminal 20, it can also be seen that the movement distance of 10 cm of the antenna is substantially no movement.

  Second, there is an advantage that by using two wireless interfaces in combination, it is possible to acquire the surrounding radio wave condition in a short time. When arranging the base station 10, there are cases where it is desired to obtain in advance the radio wave condition at the position to be arranged. In that case, by obtaining radio wave conditions in different channels using both of the two radio interfaces, the acquisition of the radio wave conditions is completed in half the time compared to the case where one radio interface is used. Can.

<Technology to reduce communication loss at channel switching>
Next, a technique for reducing communication loss when switching to the channel determined as described above will be described. Here, from the state where the base station 10 uses the wireless interface W1 as the communication interface 112 and uses the wireless interface W2 as the monitoring interface 114, the wireless interface W1 is used as the monitoring interface 114 and the wireless interface W2 is the communication interface A technique for reducing the communication loss at the time of transition to the state used as 112 will be described as an example.

  The transition corresponds to switching from the state in which the communication terminal is connected to the wireless interface W1 to the state in which the communication terminal is connected to the wireless interface W2. This switching can be realized, for example, by disconnecting the connection with the wireless interface W1 by the communication terminal and then establishing the connection with the wireless interface W2, and this case will be described below as an example. However, the switching is not limited to this. For example, the communication terminal may switch the connection from the wireless interface W1 to the wireless interface W2 only by switching the used channel without going through the steps of disconnecting and establishing the communication link. It is feasible.

  FIG. 9 is a block diagram focusing on the channel switching function of base station 10 and communication terminal 20 according to the present embodiment.

  As shown in FIG. 9, the base station 10 includes a control unit 117 and two wireless interfaces W1 and W2 as functional blocks related to channel switching.

  The wireless interfaces W1 and W2 each have a terminal list. Here, the terminal list is a list showing the communication terminal 20 connected to the wireless interface and the reception availability information indicating whether the communication terminal 20 can receive a frame (see FIG. 10). The wireless interfaces W1 and W2 correspond to a first interface and a second interface, respectively.

  The wireless interface W2 includes a queue 131 and a queue control unit 132.

  The queue 131 is an output queue for storing a frame addressed to the communication terminal 20 output by the wireless interface W2. The queue 131 is provided for each communication terminal 20, and stores frames to be transmitted to the communication terminal 20. The queue control unit 132 controls whether a frame stored in the queue 131 is output. The queue 131 is, for example, a power save queue conforming to the IEEE 802.11 standard existing in a module of the wireless interface W2, in other words, a queue realized by so-called firmware. That is, the wireless interface W2 recognizes that the communication terminal 20 is in the power saving state, and stores the frame in the queue without transmitting it until the notification frame (described later) from the communication terminal 20 is received. . Further, the queue 131 may be a queue realized by using a part of the main memory 103 by the CPU 101 executing a predetermined program, that is, a queue realized by so-called software.

  The queue control unit 132 is a processing unit that controls whether or not a frame is output from the queue 131. The queue control unit 132 refers to the terminal list of the wireless interface W 2 and outputs a frame from the queue 131 and transmits the frame to the communication terminal 20 when the communication terminal 20 can receive the frame. When the communication terminal 20 can not receive a frame, the frame is accumulated by not outputting the frame from the queue 131 (in other words, prohibiting the output).

  Specifically, the queue control unit 132 starts accumulation of frames addressed to the communication terminal 20 before the communication terminal 20 disconnects from the wireless interface W1. This is executed by the communication terminal 20 being registered in the terminal list in a frame reception impossible state.

  Then, when the communication terminal 20 connected to the wireless interface W1 disconnects the connection with the wireless interface W1 and connects to the wireless interface W2, the queue control unit 132 transmits the frame stored in the queue 131 to the wireless interface W1. It transmits to the communication terminal 20 from W2. More specifically, the queue control unit 132 transmits a frame stored in the queue 131 in response to reception of a notification frame to be transmitted after the communication terminal 20 is connected to the wireless interface W2. This is triggered by the reception of the notification frame to be transmitted after the communication terminal 20 is connected to the wireless interface W2, so that the reception availability information of the communication terminal 20 in the terminal list of the wireless interface W2 changes from "impossible" to "possible". It is executed by being changed. By doing this, it is possible to cause the communication terminal 20 to receive the frame stored in the queue 131 as early as possible after the communication terminal 20 can receive the frame.

  The functional blocks corresponding to the queue 131 and the queue control unit 132 also include the wireless interface W1, but the description will be omitted.

  The control unit 117 reads and writes the setting information and the terminal list of the wireless interfaces W1 and W2. The control unit 117 also controls the start and end of the communication function of the wireless interfaces W1 and W2.

  Specifically, the control unit 117 registers the communication terminal 20 in the terminal list of the wireless interface W2 before the communication terminal 20 connects to the wireless interface W2. At this time, the control unit 117 registers in the terminal list that the communication terminal 20 can not receive a frame.

  Further, the control unit 117 starts the communication function of the wireless interface W2 before the communication terminal 20 switches the connection from the wireless interface W1 to the wireless interface W2, and stops the communication function of the wireless interface W1 after the connection switching is completed.

  The notification frame can be realized by a frame in which the power save bit according to the IEEE 802.11 standard is 0. Using a NULL frame whose power save bit is 0 as this frame is advantageous in that the amount of communication data can be reduced. In this case, the information indicating whether the frame is receivable or not in the terminal list corresponds to information indicating an awake state or a power save state conforming to the IEEE 802.11 standard, respectively.

  The communication terminal 20 includes a notification unit 135 and a wireless interface W3 as functional blocks related to channel switching.

  The wireless interface W3 is a wireless communication interface that establishes a communication link with the wireless interface W1 or W2 of the base station 10 and performs wireless communication. When the received frame is the same as the frame received in the past, the wireless interface W3 performs processing to discard the received frame. The wireless interface W3 is, for example, a wireless LAN communication interface conforming to the IEEE 802.11a, b, g, n standards, etc., and has a wireless communication signal generation circuit, an antenna, and the like. The wireless interface W3 corresponds to a terminal interface.

  The notification unit 135 causes the wireless interface W3 to disconnect from the first channel of the base station 10 with the wireless interface W1, switches the channel, and the wireless interface W2 of the base station 10 with the second channel different from the first channel. It is a processing unit that transmits a notification frame via the wireless interface W3 when the connection is made. After the notification unit 135 transmits the notification frame, the wireless interface W2 that receives the notification frame transmits the frame stored in the queue 131, and the wireless interface W3 receives the transmitted frame. In this way, it is possible to reduce the loss in the frame received by the communication terminal 20.

  FIG. 10 is an explanatory diagram of an example of a terminal list of the wireless interface W2 of the base station 10 according to the present embodiment.

  The terminal list includes identification information of the communication terminal 20 and information indicating whether or not the frame of the communication terminal 20 can be received. In the example shown in FIG. 10, the communication terminal S1 is registered as a state in which reception of a frame is possible (valid), and the communication terminal S2 is registered as a state in which reception of a frame is impossible (impossible). ing.

  The terminal list is referred to by the queue control unit 132, and it is controlled whether the queue control unit 132 outputs a frame from the queue 131 addressed to the communication terminal 20, in other words, whether a frame is transmitted to the communication terminal 20 or not. Used to

  FIG. 11 is a flowchart focusing on the channel switching function of base station 10 according to the present embodiment.

  At the first time point (uppermost on the drawing) in FIG. 11, the base station 10 is in a state of using the wireless interface W1 as the communication interface 112 and using the wireless interface W2 as the monitoring interface 114. In addition, the frame addressed to the communication terminal 20 is transmitted from the wireless interface W1 and is not transmitted from the wireless interface W2.

  In step S201, the control unit 117 performs control to start the communication function of the wireless interface W2. Specifically, the control unit 117 causes the wireless interface W2 to transition to the state of transmitting a frame. In other words, the control unit 117 controls the wireless interface W2 to be used as the communication interface 112. From this point on, the frame addressed to the communication terminal 20 is transferred to both radio interfaces W1 and W2. The frame transferred to the wireless interface W1 is actually sent to the communication terminal 20, but the frame transferred to the wireless interface W2 will be stored in a queue as described later.

  In step S202, the control unit 117 performs control to start transmission of a frame addressed to the communication terminal 20 from the wireless interface W2. After this control, when the base station 10 obtains a frame addressed to the communication terminal 20, the communication interface 20 selects one of the wireless interfaces W1 and W2 from the wireless interface registered in the terminal list in a receivable state in the terminal list. A frame addressed to 20 will be output. If the communication terminal 20 is registered in the terminal list of each of the wireless interfaces W1 and W2 in a receivable state, a frame addressed to the communication terminal 20 is output from each of the wireless interfaces W1 and W2.

  In step S203, the control unit 117 registers the communication terminal 20 in the terminal list of the wireless interface W2 as being in a state where it can not receive a frame (power save state).

  In step S204, the queue control unit 132 controls the wireless interface W2 to start storing the frame addressed to the communication terminal 20 in the queue 131 (store in the queue 131 and do not output it). If the communication terminal 20 is registered in the power save state in step S203, accumulation of frames in step S204 is started based on the power save function conforming to the IEEE 802.11 standard.

  In step S205, the control unit 117 transmits the CSA to the communication terminal 20 from the wireless interface W1.

  In step S206, the wireless interface W1 disconnects the connection with the communication terminal 20. This is because the communication terminal 20 that has received the CSA transmitted in step S205 is a control frame for disconnecting the connection with the wireless interface W1 (Deauthentication and Deassociation). It is done by exchanging).

  In step S207, the wireless interface W2 establishes a connection with the communication terminal 20. The communication terminal 20 that has received the CSA transmitted in step S205 takes the initiative in establishing a control frame (Authentication and Connection) for establishing a connection with the wireless interface W2. It is done by exchanging.

  In step S208, the wireless interface W2 determines whether a notification frame has been received from the communication terminal 20. If the notification frame has been received (Yes in step S208), the process proceeds to step S209. If not (No in step S208), step S208 is performed again.

  In step S 209, the queue control unit 132 outputs the frame stored in the queue 131 from the queue 131 and transmits the frame to the communication terminal 20, and ends storing the frame addressed to the communication terminal 20 in the queue 131. Control.

  In step S210, the control unit 117 performs control to stop the communication function of the wireless interface W1. Specifically, the control unit 117 causes the wireless interface W1 to transition to the state of not transmitting a frame. In other words, the control unit 117 controls the wireless interface W1 to be used as the monitoring interface 114.

  Note that the process of step S202 may be performed before the process of step S206, and may be performed, for example, between step S203 and step S204 or between step S204 and step S205.

  FIG. 12 is a flowchart focusing on the channel switching function of communication terminal 20 according to the present embodiment.

  At the first time point in FIG. 12 (at the top of the drawing), the wireless interface W3 of the communication terminal 20 has established a connection with the wireless interface W1 of the base station 10.

  In step S221, the wireless interface W3 determines whether a CSA has been received from the wireless interface W1 of the base station 10. If the CSA has been received (Yes in step S221), the process proceeds to step S221. If not (No in step S221), step S221 is performed again.

  In step S222, the wireless interface W3 disconnects the connection with the wireless interface W1 of the base station 10.

  In step S223, the wireless interface W3 switches the wireless communication channel to be used based on the CSA received in step S201. Specifically, the wireless interface W3 switches the wireless communication channel to be used to the switching destination channel included in the CSA received in step S201.

  In step S224, the wireless interface W3 connects with the wireless interface W2 of the base station 10 on the changed channel changed in step S223.

  In step S225, the notification unit 135 transmits a notification frame in response to the connection of the wireless interface W3 with the wireless interface W2 of the base station 10 in step S224. The notification frame can use a NULL frame whose power save bit is 0 according to the IEEE 802.11 standard.

  In step S226, the wireless interface W3 receives the frame stored in the queue 131, which transmits the notification frame transmitted in step S225 in response to the wireless interface W2 of the base station 10 receiving the notification frame. If the NULL frame is used in step S225, the frame reception in step S226 is performed based on the power save function conforming to the IEEE 802.11 standard.

  By the above series of operations, when the wireless interface W3 of the communication terminal 20 performs handover from the wireless interface W1 of the base station 10 to the wireless interface W2, communication loss at the time of switching channels used for wireless communication is reduced. Ru. If all frames to be delivered from the base station 10 to the communication terminal 20 are stored in the queue 131 after the communication terminal 20 disconnects from the wireless interface W1 and establishes the connection to the wireless interface W2, It is also possible to make the loss zero, and in this case, the communication terminal 20 is affected only by the occurrence of a frame delay of a time (for example, about 10 msec) during which the frame is accumulated in the queue 131. Can. Therefore, it is highly useful for communication requiring immediateness.

(Modification of the embodiment)
In the present modification, a base station system or the like that reduces communication loss at the time of switching a wireless communication channel will be described for the case where the base station system is configured of a plurality of base stations.

  FIG. 13 is a block diagram focusing on the channel switching function of the base station system 10A and the communication terminal 20 according to the present modification.

  As shown in FIG. 13, the base station system 10A includes a base station 10B and a base station 10C. The base station 10B and the base station 10C are connected by the LAN 30, and the functions of the base station 10 in the above embodiment are distributed and provided. That is, the base station 10B includes the control unit 117 and the wireless interface W1, and the base station 10C includes the wireless interface W2. It differs from the above embodiment in that reading and writing of setting information and terminal list of the wireless interface W2 and start and end of the communication function of the wireless interface W2 by the control unit 117 are performed via the LAN 30.

  Base station system 10A has the same function as base station 10 in the above embodiment.

  The base station 10B and the base station 10C may be arranged close to each other (for example, with intervals of about several centimeters), and if they can cover almost the same area, the distance of about several meters to several tens of meters may be provided. It may be arranged empty.

  The communication terminal 20 is the same as the communication terminal 20 of the above embodiment. The communication terminal 20 can be switched from the state connected to the wireless interface W1 to the state connected to the wireless interface W2 as in the above embodiment.

  As described above, the base station system 10A of the present modification can dynamically determine a channel capable of wireless communication with higher quality, and can reduce communication loss when switching to the determined channel. it can.

  As described above, the base station system according to the present embodiment and the modification should be delivered to the communication terminal between the time the communication terminal disconnects the connection with the first interface and the establishment of the connection with the second interface. Store the frame in the queue. After that, when the communication terminal connects to the second interface, the frame stored in the queue is transmitted to the communication terminal. Therefore, the frame to be delivered to the communication terminal is delivered to the communication terminal without loss. Thus, the base station system reduces communication loss when switching wireless communication channels.

  Further, the base station system detects that the communication terminal is connected to the second interface by receiving the notification frame, and transmits the frame stored in the queue to the communication terminal. Thus, the base station system more easily reduces communication loss when switching wireless communication channels.

  Also, the base station system registers the communication terminal in the terminal list of the second interface before the communication terminal actually connects to the second interface. By this, when the communication terminal is actually connected to the second interface, it is possible to transmit the frame only by receiving the notification packet from the communication terminal, so the communication terminal is actually connected to the second interface It is possible to make the process after it easier.

  Further, the base station system can reduce the communication loss at the time of switching of the wireless communication channel more specifically by using the mechanism of the power save state and the power save queue conforming to the IEEE 802.11 standard.

  In addition, the base station system uses a power save state and power save queue mechanism conforming to the IEEE 802.11 standard, and reduces the data amount of notification frames to reduce communication loss when switching wireless communication channels. be able to.

  Also, the base station system can reduce communication loss when switching wireless communication channels by using one base station provided with two wireless interfaces.

  Further, two base stations provided with one wireless interface can be used to reduce communication loss when switching wireless communication channels.

  In addition, while performing wireless communication with a communication terminal by one wireless interface, the base station system acquires surrounding radio wave conditions using another wireless interface not used for the wireless communication. Then, when a suitable channel is determined based on the acquired radio wave condition, the base station system can perform channel switching so as to perform wireless communication with the communication terminal on the suitable channel. Communication loss can be reduced.

  The present invention may also be described as follows, but is not limited to the following description.

  (1) A wireless base station apparatus, which performs wireless communication with a communication terminal on one channel using a storage unit, two wireless interfaces, and a first interface which is one of the two wireless interfaces In addition, around the wireless base station apparatus using a wireless communication unit that acquires the communication status of the one channel, and a second interface that is the other of the two wireless interfaces during wireless communication by the wireless communication unit. Based on the radio wave condition stored in the storage unit, the radio wave condition stored in the storage unit, and the radio wave condition stored in the storage unit; A determination unit configured to determine a preferred channel estimated to be capable of wireless communication of higher quality than wireless communication using the one channel; In the case where control is performed to perform wireless communication with the communication terminal using the preferred channel using an interface, and the wireless communication unit is controlled to perform wireless communication using the second interface, further, the status acquisition The control unit configured to acquire the radio wave condition using the first interface and control the acquired radio wave condition to be stored in the storage unit, and the determination unit determines the preferred channel Furthermore, the wireless base station for determining the start time of the wireless communication on the preferred channel by the second interface, the control unit starting the wireless communication on the preferred channel by the second interface at the start time apparatus.

  (2) When the wireless communication unit controls to perform wireless communication using the second interface, wireless communication management information (except for the channel used) for the one channel is copied to the second interface The wireless base station apparatus according to (1), which is set.

  (3) When the wireless communication unit performs wireless communication on the preferred channel using the second interface, the wireless communication unit switches the channel of wireless communication to the preferred channel prior to the start of wireless communication on the preferred channel. The radio base station apparatus according to (1) or (2), wherein an announcement signal for announcing that is unicast transmitted to the communication terminal performing radio communication.

  (4) When acquiring the radio wave status, the status acquisition unit changes the channel, and the radio wave status is multiplied several times with the passage of time in each channel that the wireless base station apparatus can use for wireless communication. Acquiring, and the determination unit may be configured such that a band occupancy rate of wireless communication obtained from the radio wave status acquired a plurality of times stored in the storage unit is smaller than a band occupancy rate of wireless communication obtained from the communication status The radio base station apparatus according to any one of (1) to (3), wherein a channel continuing for a predetermined time or more is determined as the preferred channel.

  (5) When acquiring the radio wave status, the status acquisition unit captures a surrounding wireless communication frame in each channel that the wireless base station apparatus can use for wireless communication while changing the channel, The determination unit determines a channel with a low degree of congestion as the preferred channel based on the status of the wireless communication obtained from the log of the wireless frame capture acquired a plurality of times stored in the storage unit (1) to The wireless base station device according to any one of (3).

  (6) The determination unit further performs (a) wireless communication using the one channel based on the communication status acquired by the wireless communication unit and the radio wave status stored in the storage unit. The candidate channel estimated to be capable of higher quality wireless communication is determined, and (b) if the candidate channel is included in the frequency band where the radar wave may exist, the presence or absence of the radar wave in the candidate channel is determined. (C) The radio base station apparatus according to any one of (1) to (5), which makes the status acquisition unit monitor and (c) determines the candidate channel as a preferred channel when no radar wave is detected in the candidate channel.

  (7) The wireless base station apparatus according to any one of (1) to (6) and the wireless communication unit using the first interface of the wireless base station apparatus perform wireless communication in the one channel, A wireless communication system, comprising: the wireless communication unit using the second interface and the communication terminal performing wireless communication on the preferred channel after the wireless communication unit is controlled to use the second interface.

  (8) A control method of a wireless base station device, wherein the wireless base station device includes a storage unit and two wireless interfaces, and the control method is any one of the two wireless interfaces. The wireless communication step of performing wireless communication with a communication terminal on one channel using one interface and obtaining the communication status of the one channel, and the two wireless interfaces during wireless communication in the wireless communication step Obtaining the radio wave condition around the wireless base station apparatus using the second interface which is the other of the above, and storing the acquired radio wave condition in the storage unit; Based on the communication status and the radio wave status stored in the storage unit, wireless communication of higher quality than wireless communication using the one channel is performed. In the determination step of determining a preferred channel estimated to be possible, and when performing wireless communication on the preferred channel using the second interface, (a) prior to the start of wireless communication on the preferred channel, An announcement signal for announcing that the channel should be switched to the preferred channel is unicast transmitted to the communication terminal performing wireless communication, and (b) the first interface applies to the one channel used for wireless communication. Setting wireless communication management information (excluding use channel information) to perform wireless communication using the second interface; and using the second interface in the wireless communication step, the communication terminal on the preferred channel And a control step of controlling to perform wireless communication.

  According to the above (1), while performing wireless communication with the communication terminal with one wireless interface, the wireless base station apparatus uses the other wireless interface not used for this wireless communication to monitor the surrounding radio wave condition. get. And when a suitable channel is determined based on the acquired electric wave condition, channel switching can be performed so that wireless communication with the communication terminal concerned may be performed by a suitable channel. Also, when the communication terminal performs channel switching, since both the wireless interface operating on the channel performing wireless communication and the wireless interface operating on the preferred channel are present, the wireless associated with the channel switching The disconnection time of communication can be shortened as much as possible. Therefore, the radio base station apparatus can dynamically determine a channel capable of radio communication with higher quality, and is suitable for a time zone in which radio communication with a communication terminal is small depending on the purpose of use of radio communication. Channel switching to the channel can be performed. As a result, it is possible to suppress the influence of the interruption time of the wireless communication accompanying the channel switching.

  According to the above (2), since the wireless base station apparatus uses exactly the same parameters for communication in the two interfaces except for the communication channel, it is possible to minimize wireless communication disconnection time with the wireless terminal. .

  According to the above (3), the radio base station apparatus can surely notify the channel change to the radio terminal side.

  According to the above (4), the radio base station apparatus can continuously acquire the radio wave condition of each usable channel by the radio interface of the one not used for radio communication. Then, the radio base station apparatus may appropriately determine a suitable channel based on the radio wave condition acquired for a relatively long time, for example, several hours or several days, and the communication condition of radio communication. it can.

  According to the above (5), the radio base station apparatus can continuously acquire the radio wave condition of each usable channel by the radio interface of the one not used for the radio communication. Then, the radio base station apparatus may appropriately determine a suitable channel based on the radio wave condition acquired for a relatively long time, for example, several hours or several days, and the communication condition of radio communication. it can.

  According to the above (6), even when using a channel included in a frequency band in which weather radar waves may exist as a preferred channel, the wireless base station device appropriately determines the preferred channel using two wireless interfaces. Thus, the disconnection time of wireless communication accompanying channel switching can be shortened as much as possible.

  According to said (7), a radio | wireless communications system has an effect similar to said radio base station apparatus.

  According to (8), the radio base station apparatus achieves the same effect as the above radio base station apparatus.

  As mentioned above, although the wireless base station apparatus of this invention was demonstrated based on embodiment, this invention is not limited to this embodiment. Without departing from the spirit of the present invention, various modifications that may occur to those skilled in the art may be made to the present embodiment, or a form constructed by combining components in different embodiments is also included in the scope of the present invention. .

  The radio base station apparatus of the present invention can dynamically determine a channel capable of radio communication with higher quality. Specifically, it can be used for a wireless base station apparatus in an office, a factory, or a house.

1, 1A wireless communication system 10, 10B, 10C base station 10A base station system 20 communication terminal 30 LAN
40 Network 101 CPU
102 ROM
103 main memory 104 storage 111 wireless communication unit 112 communication interface 113, 113A status acquisition unit 114 monitoring interface 115 storage unit 116, 116A determination unit 117 control unit 121 status history 131 queue 132 queue control unit 135 notification unit 501 time 502 transmission Original address 503 Destination address 504 Communication channel 505 Frame length 601 Number of terminals 602 Number of base stations 603 Number of communication frames 604 Communication data amount W1, W1A, W2, W2A, W3 Wireless interface

Claims (10)

Ri Der capable of wireless communication with the first channel, a first interface for storing the wireless communication management information is management information necessary for communication terminal of a wireless connection,
A second interface capable of wireless communication on a second channel different from the first channel;
And queue for storing the communication terminal addressed frames output by the second interface,
When the communication terminal connected to the first interface switches the connection from the connection with the first interface to the second interface, the frame stored in the queue is transmitted from the second interface to the communication terminal and queue control unit to be sent to,
Before the communication terminal connects to the second interface without receiving a notification from the communication terminal that the communication terminal is in the power saving state, the communication terminal is in the power saving state before the communication terminal is connected to the second interface. A control unit which registers the wireless communication management information in the second interface and registers the wireless communication management information in the second terminal list;
The queue control unit changes the communication terminal to an awake state in the terminal list upon reception of a notification frame to be transmitted after the communication terminal is connected to the second interface, and is stored in the queue. Base station system that transmits frames . Said second interface, the base station system according to claim 1 which holds the first interface identical settings and information. The control unit registers, when registering the communication terminal in the terminal list, information indicating that the communication terminal is in a power saving state conforming to the IEEE 802.11 standard,
The base station system according to claim 2 , wherein the queue is a power save queue conforming to the IEEE 802.11 standard. The base station system according to claim 3 , wherein the notification frame is a NULL frame in which a power save bit conforming to the IEEE 802.11 standard is zero. The base station system comprises one base station,
The base station system according to any one of claims 1 to 4 , wherein the one base station comprises the first interface and the second interface. The base station system comprises a first base station and a second base station.
The first base station comprises the first interface;
The base station system according to any one of claims 1 to 4 , wherein the second base station comprises the second interface. The base station system further comprises
A wireless communication unit that performs wireless communication with the communication terminal on the first channel using the first interface, and acquires the communication status of the first channel;
A state acquisition unit configured to acquire a radio wave condition around the second interface using the second interface during wireless communication by the wireless communication unit, and store the acquired radio wave condition in a storage unit;
Preferably, based on the communication status acquired by the wireless communication unit and the radio wave status stored in the storage unit, it is estimated that wireless communication of higher quality than wireless communication using the first channel can be performed. And a determination unit that determines a channel,
The second interface is
Wirelessly communicate with the communication terminal on the preferred channel;
The queue control unit
Using the preferred channel as the second channel, if the communication terminal is connected to the second interface, according to any one of claims 1 to 6, transmitting the frames stored in the queue Base station system. The base station system according to any one of claims 1 to 7 .
And a communication terminal connected to the base station system. A method of controlling a base station system
The base station system
Ri Der capable of wireless communication with the first channel, a first interface for storing the wireless communication management information is management information necessary for communication terminal of a wireless connection,
A second interface capable of wireless communication on a second channel different from the first channel;
A queue provided to the second interface;
The control method is
Storing said communication terminal addressed frames output by the second interface,
When the communication terminal connected to the first interface switches the connection from the connection with the first interface to the second interface, the frame stored in the queue is transmitted from the second interface to the communication terminal and the step of transmitting to,
Before the communication terminal connects to the second interface without receiving a notification from the communication terminal that the communication terminal is in the power saving state, the communication terminal is in the power saving state before the communication terminal is connected to the second interface. Registering the wireless communication management information in the second interface and storing the wireless communication management information in the second terminal list;
Changing the communication terminal to an awake state in the terminal list and transmitting a frame stored in the queue upon reception of a notification frame to be transmitted after the communication terminal is connected to the second interface And control method. A program for realizing the control method according to claim 9 by a computer.

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