JP2008118432A - System, method, and program for flow control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control traffic flow for a wireless station or a wireless terminal that is a cause of congestion in a wireless network. <P>SOLUTION: A flow control system controls traffic flow in each wireless station in the wireless network that includes a plurality of wireless stations. Each of the wireless stations has a flow control target specifying means for specifying a wireless station connected to a transmission source terminal that is a cause of traffic congestion based on frames stored in a frame storage means for temporarily storing received frames, a transfer rate control frame transmission means for transmitting a transfer rate control frame that controls a transfer rate to the wireless station specified by the flow control target specifying means, and a transmission control frame transmission means for transmitting a transmission control frame to the connected wireless terminal when receiving the transfer rate control frame. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flow control system, a flow control method, and a flow control program. For example, in a multi-hop wireless communication system including a plurality of wireless stations, a specific wireless that causes the congestion when the network is congested. It can be applied to a system for controlling the flow of a station or a wireless terminal.

  In a multi-hop wireless network, a network can be configured with a plurality of wireless stations having a packet relay function, and packets can be transferred to adjacent wireless stations by relaying packets between adjacent wireless stations. .

  By applying this multi-hop relay function to a wireless LAN and wirelessly connecting the APs (Access Points) that are the base stations of the wireless LAN, it is possible to reduce the cost of installing a wired network that has been conventionally required for the installation of APs. It becomes possible to reduce.

  A technique related to a wireless LAN having such a multi-hop function is disclosed in Patent Document 1. Patent Document 1 discloses a technique in which a frame received by an AP from a wireless terminal is encapsulated with an IP packet, and packet relay is realized toward a desired AP using an IP layer routing protocol. However, when the technique described in Patent Document 1 is used, there is a risk that the throughput may decrease due to an increase in overhead due to encapsulation, a processing delay in encapsulation / decapsulation at the radio station, and the like.

For this reason, the IEEE 802.11 committee, which is a wireless LAN standardization organization, is proceeding with standardization for wireless LAN mesh expansion as IEEE 802.11s, and this standardization includes a multi-hop routing function in the MAC layer. include.
JP 2003-333053 A

  In the above-described multi-hop wireless communication network system, traffic exceeding the transfer capability of the wireless station may arrive due to an increase in the amount of relay traffic. As a result, the allowable capacity of the buffer that temporarily holds the packet may be exceeded, and the packet may be discarded due to a buffer overflow.

  Therefore, in the IEEE802.11s draft, it is considered that a control signal that suppresses the transfer rate is sent to the surrounding wireless stations when local congestion occurs. The peripheral wireless station that has received this control signal can suppress local congestion by changing to the instructed transfer rate.

  However, traffic that causes buffer overflow does not necessarily occur from neighboring radio stations. This is because the traffic of a radio station several pops away from the multi-hop relay may affect the congestion.

  For this reason, it is desired to realize a flow control that detects a radio station that causes congestion and suppresses the transfer rate of the radio station.

  In the IEEE802.11s draft, a specific method for suppressing the transfer rate is not specified in the radio station that has received the control signal for suppressing the transfer rate, and is outside the standard range.

  As an example, there is a method of changing the transmission waiting time of frames classified for each category defined in IEEE802.11e, but if the wireless station does not support the IEEE802.11e function, Do not work. Therefore, it is desired to realize a transfer rate suppression method that can operate with the standard functions of IEEE 802.11.

  Therefore, in a wireless network including a plurality of wireless stations having packet relay means, when congestion occurs in the network, it is possible to identify the wireless station or wireless terminal that is the cause of the congestion. There is a need for a flow control system, a flow control method, and a flow control program that can control a traffic flow for a wireless terminal.

  In order to solve this problem, a flow control system according to a first aspect of the present invention is a flow control system for controlling traffic flow in each wireless station in a wireless network configured by including a plurality of wireless stations having packet relay means. (1) Frame holding means for temporarily holding a received frame, and (2) a connection with a transmission source terminal that causes traffic congestion based on the frame held in the frame holding means. A flow control target specifying means for specifying a connected wireless station, and (3) transmitting a transfer rate control frame for suppressing the transfer rate from the connected wireless terminal to the wireless station specified by the flow control target specifying means A transfer rate control frame transmitting means for performing (4) a transfer rate control frame, and upon receiving the transfer rate control frame, Characterized in that it comprises a transmission suppression frame transmitting means for transmitting a transmission suppression frame to suppress the transmission period transmission frame.

  According to a second aspect of the present invention, there is provided a flow control method for controlling a traffic flow in each wireless station in a wireless network including a plurality of wireless stations having packet relay means. A holding means, a flow control target specifying means, a transfer rate control frame transmitting means, and a transmission suppression frame transmitting means. (1) The flow control target specifying means is based on a frame held in the frame holding means. A flow control target specifying step for specifying a radio station connected to the transmission source terminal of the cause of traffic congestion, and (2) a transfer rate control frame transmitting means for the radio station specified by the flow control target specifying means A transfer rate control frame that transmits a transfer rate control frame that suppresses the transfer rate from the connected wireless terminal And (3) a transmission suppression frame for transmitting a transmission suppression frame for suppressing transmission of a transmission frame for a predetermined period to a connected wireless terminal when the transmission suppression frame transmission means receives the transfer rate control frame. A transmission step.

  According to a third aspect of the present invention, there is provided a flow control program for controlling a traffic flow in each radio station in a radio network including a plurality of radio stations having packet relay means. (1) Frame holding means for temporarily holding a received frame, (2) Identifying a radio station connected to the transmission source terminal of the traffic congestion factor based on the frame held in the frame holding means Flow control target specifying means; (3) a transfer rate control frame transmitting means for transmitting a transfer rate control frame for suppressing a transfer rate from a connected wireless terminal to a radio station specified by the flow control target specifying means; (4) When a transfer rate control frame is received, a transmission frame for a predetermined period is transmitted to the connected wireless terminal. Program to function as a transmission suppression frame transmitting means for transmitting a transmission suppression frame to suppress the transmission of the beam.

  According to the present invention, in a wireless network including a plurality of wireless stations having packet relay means, when congestion occurs in the network, it is possible to identify the wireless station and the wireless terminal that are the cause, and the identification It is possible to control the traffic flow for the wireless stations and wireless terminals.

(A) First Embodiment Hereinafter, a first embodiment of a flow control system, a flow control method, and a flow control program of the present invention will be described with reference to the drawings.

  In the first embodiment, the flow control system, the flow control method, and the flow control program of the present invention are applied to the wireless stations that constitute the multi-hop wireless communication system, and the wireless stations and wireless terminals that are traffic congestion factors are specified. An embodiment for controlling the transfer rate will be described.

(A-1) Configuration of the First Embodiment FIG. 2 is a configuration diagram showing a configuration of a network including the multi-hop wireless communication system (network) of the first embodiment.

  In FIG. 2, the network 200 according to the first embodiment includes at least wireless stations 201 to 204, wireless terminals 211 to 214, a router 205, and an IP network 206.

  The wireless stations 201 to 204 are wirelessly connected to wireless terminals. The radio stations 201 to 204 have a relay function for relaying received frames to adjacent radio stations toward a transmission destination. As a result, the frame can be transferred to a wireless station where radio waves do not reach directly.

  The wireless stations 201 to 204 have a function for detecting a traffic congestion state, a function for specifying a wireless station and / or a wireless terminal that is a congestion factor when detecting the congestion state, and a specific function that is a congestion factor. A function for instructing a radio station and / or a radio terminal for flow control, a function for controlling a transfer rate for a radio terminal to be connected when an instruction for flow control is received, and the like are provided. A detailed description of the functional configuration realized by the radio stations 201 to 204 will be described later.

  The wireless station 201 further has a gateway function for connecting to the IP network 206. Thereby, communication between the wireless terminal and the IP network 206 can also be realized.

  The wireless terminals 211 to 214 are wirelessly connected to the wireless stations 201 to 204. In FIG. 2, it is assumed that the wireless terminal 211 is connected to the wireless station 202, the wireless terminal 212 is connected to the wireless station 203, and the wireless terminals 213 and 214 are connected to the wireless station 204.

  The router 205 relays IP packets between the IP network 206 and the wireless station 201 functioning as a gateway.

  The IP network 206 is a network that employs IP (Internet Protocol), such as the Internet or an intranet. As the IP network 206, a wired network, a wireless network, a network obtained by combining these, or the like can be applied.

  FIG. 1 is a functional block diagram showing an internal configuration of a relay function of radio stations 201 to 204 (shown as radio station 100 in FIG. 1).

  In FIG. 1, a radio station 100 includes an antenna unit 101, an amplifier 102, a radio transmission / reception unit 103, a frame analysis unit 104, a routing table unit 105, a relay buffer unit 106, a buffer monitoring unit 107, a transfer rate control frame generation unit 108, a CTS. A (Clear To Send) transmission unit 109 is included.

  The antenna unit 101 transmits and receives radio signals. When receiving a radio signal, the antenna unit 101 gives the received radio signal to the radio transceiver unit 103, and when transmitting the radio signal, the amplifier 102 transmits a signal whose radio signal strength is increased. A signal is transmitted.

  When transmitting a transmission signal, the amplifier 102 receives the transmission signal from the wireless transmission / reception unit 103, increases the signal strength of the radio wave, and transmits the signal via the antenna unit 101.

  The wireless transmission / reception unit 103 performs modulation / demodulation processing, frequency conversion processing, and the like. That is, when receiving a radio signal, the radio transmission / reception unit 103 performs frequency conversion on the received signal to a level that can be demodulated, performs a predetermined demodulation process, and transmits the demodulated signal obtained by the demodulation process to a frame. When the transmission signal is transmitted to the analysis unit 104 and the transmission signal is transmitted, a predetermined modulation process is performed on the transmission signal and the signal is supplied to the amplifier 102.

  When the frame analysis unit 104 receives the demodulated signal (reception frame) from the wireless transmission / reception unit 103, the frame analysis unit 104 analyzes the header portion of the reception frame.

  The routing table unit 105 has route information to the wireless station and each wireless terminal. This route information includes route information indicating which wireless terminal is currently connected to which wireless station. Various methods can be used as a method for the routing table unit 105 to create route information. For example, it can be realized by exchanging control packets between wireless stations.

  The relay buffer unit 106 temporarily stores received frames. In addition, the relay buffer unit 106 temporarily holds the frame, gives it to the wireless transmission / reception unit 103, and relays the frame.

  The buffer monitoring unit 107 monitors the usage state of the relay buffer unit 106. The buffer monitoring unit 107 monitors the stationary state of the relay buffer unit 106, so that it can be determined whether or not the wireless station 100 is in a congestion state. As a method for determining the congestion state, when the number of frames (or data amount) retained in the relay buffer unit 106 exceeds a threshold, it is determined that the congestion state is present. Further, the buffer monitoring unit 107 checks the frame occupancy ratio in the relay buffer unit 106 by confirming the transmission source of the frame based on the header information of the frame stopped in the relay buffer unit 106 in the congested state. It investigates and identifies the radio stations that are connected to radio terminals with high traffic.

  When the wireless station 100 is in a congested state, the transfer rate control frame generation unit 108 generates a transfer rate control frame requesting to suppress the transfer rate, and transfers the transfer rate control frame to the wireless station specified by the buffer monitoring unit 107. A rate control frame is transmitted.

  When the CTS transmission unit 109 receives a transfer rate control frame from another wireless station, the CTS transmission unit 109 transmits the CTS control frame at a constant period.

(A-2) Operation of First Embodiment Next, the flow control processing operation in the network 200 of the first embodiment will be described in detail with reference to the drawings.

  FIG. 3 is a sequence diagram illustrating an operation of a flow control process according to the first embodiment. In FIG. 3, a case where the wireless station 202 instructs flow control on behalf of the wireless station will be described as an example.

  In FIG. 3, it is assumed that the wireless terminal 212 is wirelessly connected to the wireless station 203, and the wireless terminals 213 and 214 are wirelessly connected to the wireless station 204. Then, it is assumed that communication with each desired destination terminal is realized by relaying radio signals between the radio stations.

  First, in the radio station 202, the incoming radio signal is subjected to predetermined demodulation processing, frequency conversion processing, and the like by the radio transmission / reception unit 103, and the demodulated signal is given to the frame analysis unit 104. The demodulated signal is analyzed by the frame analysis unit 104 for frame header information, the routing table unit 105 is referenced to determine the next transfer destination of the frame, and the frame subjected to the routing process. Is temporarily held in the relay buffer unit 106.

  In the wireless station 202, the buffer monitoring unit 107 monitors the frame stop state of the relay buffer unit 106, and determines whether or not it is in a congestion state by comparing the thresholds (step S301).

  When the buffer monitoring unit 107 determines that the congestion state is present, the buffer monitoring unit 107 selects a wireless terminal with a large amount of traffic based on a frame held in the relay buffer unit 107 and a wireless station to which the wireless terminal is connected. It investigates and selects the radio station of the congestion factor (step S302).

  Here, a method of selecting a radio station that is a congestion factor will be described with reference to FIG. FIG. 4 is a diagram showing how frames are held in the relay buffer unit 106. In FIG. 4, a frame having a large number of black dots indicates a frame from the wireless terminal 212, a black frame indicates a frame from the wireless terminal 214, and a hatched frame indicates a frame from the wireless terminal 213.

  The buffer monitoring unit 107 checks the transmission source of each frame based on the header information of the frame in the relay buffer unit 106, obtains the occupation ratio of each frame in the relay buffer unit 106, and occupies the frame from which wireless terminal Ask what you are doing. That is, in the example of FIG. 4, it can be seen that 50% of the frames from the wireless terminal 213, 30% of the frames from the wireless terminal 212, and 20% of the frames from the wireless terminal 214.

  When the usage status of the relay buffer unit 107 is obtained in this way, the buffer monitoring unit 107 checks which radio station is connected to each radio terminal while referring to the routing table unit 105, and determines which radio station The wireless station with the largest traffic volume is selected as the target of flow control. That is, in the example of FIG. 4, the buffer monitoring unit 107 selects the wireless station 4 that accommodates the wireless terminals 213 and 214.

  When the flow monitoring target radio station is selected by the buffer monitoring unit 107, the transfer rate control frame generation unit 108 generates and transmits a transfer rate control frame destined for the radio station 204 (step S303). This transfer rate control frame is relayed by the wireless station 203 in multihop. Here, the transfer rate control frame describes information such as a target transfer rate and a period during which the transfer rate is suppressed.

  When the transfer rate control frame from the wireless station 202 is given to the wireless station 204, the frame analysis unit 104 of the wireless station 204 analyzes the information described in the transfer rate control frame, and controls the transfer rate based on the content. Conditions are set (step S304).

  Next, in the wireless station 204, in order to control the transmission rate from the accommodated wireless terminals 213 and 214, the CTS transmission unit 109 transmits a CTS control frame with the MAC address of the wireless station 204 as a receiving station address. It transmits to the interface which 213 and 214 have. (Step S305).

  Here, normally, the CTS control frame is used as a pair with an RTS (Request To Send) control frame as a countermeasure for the hidden terminal problem, and when there is a frame to be transmitted to a wireless terminal or a wireless station, the purpose is to reserve a transmission period. It is used in. The RTS / CTS control frame describes a period during which a wireless terminal called NAV (Network Allocation Vector) prohibits transmission.

  Therefore, in the first embodiment, the CTS transmission unit 109 of the wireless station 204 transmits the CTS control frame in which the NAV is described to the wireless terminals 213 and 214. As a result, the wireless terminals 213 and 214 cannot transmit frames during the transmission prohibited period.

  Note that although the MAC address of the wireless station 204 is described in the receiving station address of the CTS control frame, it is not necessary to transmit a data frame from the wireless station because the transmission period is not reserved by the RTS control frame.

  After that, the wireless station 204 suppresses frame transmission from the wireless terminals 213 and 214 by periodically transmitting CTS control frames until the condition at which the transfer rate control period set in step S304 ends (step S306). .

  In the wireless station 202, when the buffer monitoring unit 107 continues to monitor the usage state of the relay buffer unit 106 and the congestion state has not yet been resolved, the wireless station that has occupied the relay buffer 106 second most frequently. In order to suppress the traffic from the terminal 212, a transfer rate control frame is transmitted to the wireless station 203 that accommodates the wireless terminal 212 (step S307).

  After that, as in steps S304 to S306, by periodically transmitting a CTS control frame with the MAC address of the wireless station 203 as the receiving station address to the wireless terminal 212, frame transmission from the wireless terminal 212 can be suppressed. The transmission rate is controlled (steps S308 to S310).

  Note that by using different frequency channels for the radio channel accommodating the radio terminal and the radio channel for relaying between the radio stations, the transmission rate of the radio terminal can be suppressed without reducing the relay throughput between the radio stations. It becomes possible.

  In the first embodiment, the radio station and the radio terminal are selected based on the monitoring state of the relay buffer unit 106. However, the radio terminal suppresses the transfer rate based on the statistical value of the traffic arriving at the radio station. Or a radio station may be selected.

(A-3) Effect of First Embodiment As described above, according to the first embodiment, when the wireless station is in a congested state, the wireless station flows to a wireless station with a large amount of traffic. Since a radio station with a large amount of traffic can be controlled by issuing a control instruction, congestion due to a buffer overflow of the radio station can be avoided.

(B) Second Embodiment Next, a second embodiment of the flow control system, the flow control method, and the flow control program of the present invention will be described with reference to the drawings.

  Similarly to the first embodiment, the second embodiment applies the flow control system, the flow control method, and the flow control program of the present invention to the radio stations that constitute the multi-hop wireless communication system, and causes traffic congestion. An embodiment for specifying a wireless station and a wireless terminal and controlling the transfer rate will be described.

  The second embodiment relates to a flow control process in a wireless station (corresponding to the wireless station 201 in FIG. 2) connected to a wired network.

(B-1) Configuration of Second Embodiment FIG. 5 is a functional block diagram showing a functional configuration of a relay function of the radio station 400 of the second embodiment. In FIG. 5, the radio station 400 of the second embodiment includes an antenna unit 101, an amplifier 102, a radio transmission / reception unit 103, a frame analysis unit 104, a routing table unit 105, a relay buffer unit 106, a buffer monitoring unit 107, and a transfer rate control. The frame generation unit 108, a CTS (Clear To Send) transmission unit 109, a wired NW transmission / reception unit 110, and a flow rate control unit 111 are included.

  The difference from the configuration of the radio station 100 of the first embodiment shown in FIG. 1 is that the second embodiment radio station 400 of FIG. 5 adds a wired NW transmission / reception unit 110 and a flow rate control unit 111. .

  The wired NW transmission / reception unit 110 transmits / receives a signal to / from the wired network 206 to be connected. That is, the wired NW transmission / reception unit 110 gives the reception signal given from the wired network 206 to the frame analysis unit 104 via the flow rate control unit 111. In addition, a transmission signal to the wired network 206 is received from the relay buffer unit 106 via the flow rate control unit 111 and transmitted to the wired network 206.

  The flow rate control unit 111 temporarily holds a frame exchanged with the wired network in a buffer, and limits the flow rate to the wireless network.

(B-2) Operation of Second Embodiment Next, the flow control processing operation in the network of the second embodiment will be described with reference to the drawings.

  FIG. 6 is a sequence diagram illustrating an operation of a flow control process according to the second embodiment. In FIG. 6, the radio station 203 detects the congestion state, selects the radio stations 201 and 202 as congestion factors, and transmits a transfer rate control frame to the radio stations 201 and 202 in the same manner as in the first embodiment. An example of the case will be described.

  First, in the unrelated station 203, as in the first embodiment (steps S301 and S302 in FIG. 4), the buffer monitoring unit 107 changes the frame of the relay buffer unit 106 from the frame suspension state to the wireless station 203 in the congestion state. It is determined that there is, and a radio station that becomes a congestion factor is selected (steps S601 and S602).

  Here, it is assumed that the traffic transferred from the router 205 is the largest. It is assumed that each wireless terminal accesses the IP network 206 and a download communication service such as Web traffic is performed.

  Next, the wireless station 203 uses the transfer rate control frame generation unit 108 to transmit a transfer rate control frame destined for the wireless station 201. This control frame is relayed by multihop by the wireless station 202 (step S603).

  The transfer rate control frame describes information such as a target transfer rate and a period during which the transfer rate is suppressed. The wireless station 201 that has received the transfer rate control frame sets a control condition for controlling the transfer rate based on the contents described in the frame (step S604).

  The difference from the first embodiment is that the flow control target is not the traffic transmitted from the wireless terminal but the traffic flowing in from the wired network. Therefore, in the wireless station 201, the flow rate control unit 111 restricts the flow of traffic received from the wired network transmission / reception unit 110 into the wireless network (step S605).

  Here, as a method of restricting the flow rate, for example, a method using a token bucket or the like is conceivable, and for example, an existing method described in, for example, Japanese Patent Application Laid-Open No. 2005-217894 can be applied. This flow restriction from the wired network is continued up to the control condition set in step S604 (step S606).

  In the wireless station 203, if the buffer monitoring unit 107 continues to monitor the use state of the relay buffer unit 106 and the congestion state has not yet been resolved, the wireless station that has occupied the relay buffer 106 second most frequently. In order to suppress the traffic from the terminal 211, a transfer rate control frame is transmitted to the wireless station 202 that accommodates the wireless terminal 211 (step S607).

  Thereafter, similarly to steps S304 to S306 of the first embodiment, a CTS control frame with the MAC address of the wireless station 202 as a receiving station address is periodically transmitted to the wireless terminal 211, so that the wireless terminal 211 Since frame transmission can be suppressed, the transmission rate is controlled (steps S608 to S610).

(B-3) Effect of Second Embodiment As described above, according to the second embodiment, the same effect as that of the first embodiment is obtained, and a terminal that becomes a congestion factor is accommodated in the radio station. Even when the terminal is not a wireless terminal, traffic arriving at the wireless station can be suppressed, and congestion due to the buffer overflow of the wireless station can be avoided.

(C) Other Embodiments (C-1) Various functional configurations of the relay function of the wireless station described in the first and second embodiments described above are realized by software processing by a computer. Of course, if it can be realized by hardware, it may be realized by hardware.

(C-2) In the first and second embodiments, the present invention can also be applied to a case where the wireless terminal accommodated by the own wireless station is a wireless terminal causing congestion. In this case, the transfer rate control frame is given to the frame analysis unit 104 in the own radio station, so that the function of the CTS transmission unit 109 can be executed.

(C-3) In the first and second embodiments, a wireless station accommodating a wireless terminal that is a congestion factor generally uses a CTS control frame that solves the hidden terminal problem to transmit a frame of the wireless terminal. The case of suppressing was explained. However, if it is possible to suppress the frame transmission of the wireless terminal, a transmission suppression frame that is a unique control frame may be provided.

  In the first and second embodiments, the case has been described where CTS control frames in which a certain transmission prohibition period (NAV) is described are continuously transmitted for a period that satisfies a set control condition. However, the transmission prohibition period described in the control frame may be a period according to the set control condition.

It is a functional block diagram which shows the function structure of the relay function which the radio station of 1st Embodiment has. It is a block diagram which shows the whole network structure of 1st Embodiment. It is a sequence diagram explaining the flow control operation | movement of 1st Embodiment. It is explanatory drawing explaining the mode of the flame | frame hold | maintained at the relay buffer part of 1st Embodiment. It is a functional block diagram which shows the function structure of the relay function which the radio station of 2nd Embodiment has. It is a sequence diagram explaining the flow control operation of 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 200 ... Network, 201-204 ... Wireless station, 205 ... Router, 206 ... IP network, 211-214 ... Wireless terminal, 100 ... Wireless station, 101 ... Antenna part, 102 ... Amplifier, 103 ... Wireless transmission / reception part, 104 ... Frame Analysis unit 105. Routing table unit 106. Relay buffer unit 107 107 Buffer monitoring unit 108 Transfer rate control frame generation unit 109 CTS transmission unit

Claims (7)

In a flow control system for controlling the traffic flow in each wireless station in a wireless network having a plurality of wireless stations having packet relay means,
Each of the above radio stations
Frame holding means for temporarily holding received frames;
Based on the frame held in the frame holding means, a flow control target specifying means for specifying a radio station connected to the transmission source terminal of the traffic congestion factor,
A transfer rate control frame transmitting means for transmitting a transfer rate control frame for suppressing a transfer rate from a connected wireless terminal to the wireless station specified by the flow control target specifying means;
A flow control system comprising: a transmission suppression frame transmission unit that transmits a transmission suppression frame that suppresses transmission of a transmission frame for a predetermined period to a connected wireless terminal when receiving the transfer rate control frame. .   2. The flow control system according to claim 1, wherein the flow control target specifying unit specifies a source terminal of a congestion factor based on a frame occupation ratio for each source terminal in the frame holding unit. Each wireless station comprises a routing table storage means for storing a routing table indicating a wireless terminal connected to each wireless station constituting the wireless network,
3. The flow according to claim 2, wherein the flow control target specifying unit specifies the wireless station connected to a transmission source terminal having a large frame occupation ratio in the frame holding unit with reference to the routing table. Control system.   The flow control system according to claim 1, wherein the transmission suppression frame is a CTS control frame. Of the above wireless stations, wireless stations connected to the wired network
The flow control system according to claim 1, further comprising a flow restriction unit that restricts a traffic flow from the wired network when a traffic congestion factor is traffic from the wired network. . In a flow control method for controlling a traffic flow in each wireless station in a wireless network including a plurality of wireless stations having packet relay means,
Each of the radio stations includes a frame holding unit, a flow control target specifying unit, a transfer rate control frame transmitting unit, and a transmission suppression frame transmitting unit.
The flow control target specifying unit specifies a radio station connected to the transmission source terminal of the traffic congestion factor based on the frame held in the frame holding unit;
The transfer rate control frame transmission means transmits a transfer rate control frame for suppressing a transfer rate from a connected wireless terminal to the radio station specified by the flow control target specifying means. Process,
When the transmission suppression frame transmission means receives the transfer rate control frame, the transmission suppression frame transmission unit transmits a transmission suppression frame that suppresses transmission of a transmission frame for a predetermined period to a connected wireless terminal. A flow control method characterized by the above. In a flow network for controlling a traffic flow in each wireless station in a wireless network including a plurality of wireless stations having packet relay means,
In each wireless station computer,
Frame holding means for temporarily holding received frames;
Based on the frame held in the frame holding means, a flow control target specifying means for specifying a radio station connected to the transmission source terminal of the traffic congestion factor,
A transfer rate control frame transmitting means for transmitting a transfer rate control frame for suppressing a transfer rate from a connected wireless terminal to the wireless station specified by the flow control target specifying means;
A flow control program that, when receiving the transfer rate control frame, functions as a transmission suppression frame transmission unit that transmits a transmission suppression frame that suppresses transmission of a transmission frame for a predetermined period to a connected wireless terminal.

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